Science.gov

Sample records for room temperature solid

  1. Coherent population trapping in a crystalline solid at room temperature

    NASA Astrophysics Data System (ADS)

    Kolesov, Roman

    2005-11-01

    Observation of coherent population trapping (CPT) at ground-state Zeeman sublevels of Cr3+ ion in ruby at room temperature is reported. A mechanism of CPT, not owing to optical pumping, is revealed in a situation when the optical pulse duration is shorter than the population decay time from the excited optical state.

  2. Entang-bling: Observing quantum correlations in room-temperature solids

    NASA Astrophysics Data System (ADS)

    Walmsley, I. A.; Lee, K. C.; Sprague, M.; Sussman, B.; Nunn, J.; Langford, N.; Jin, X.-M.; Champion, T.; Michelberger, P.; Reim, K.; Uk, D.; Jaksch, D.

    2013-06-01

    Quantum entanglement in the motion of macroscopic solid bodies has implications both for quantum technologies and foundational studies of the boundary between the quantum and classical worlds. Entanglement is usually fragile in room-temperature solids, owing to strong interactions both internally and with the noisy environment. We generated motional entanglement between vibrational states of two spatially separated, millimeter-sized diamonds at room temperature. By measuring strong nonclassical correlations between Raman-scattered photons, we showed that the quantum state of the diamonds has positive concurrence with 98% probability. Our results show that entanglement can persist in the classical context of moving macroscopic solids in ambient conditions.

  3. Designing room-temperature multiferroic materials in a single-phase solid-solution film

    NASA Astrophysics Data System (ADS)

    Mao, H. J.; Song, C.; Cui, B.; Peng, J. J.; Li, F.; Xiao, L. R.; Pan, F.

    2016-09-01

    The search for multiferroic materials with simultaneous ferroelectric and ferromagnetic properties in a single phase at room temperature continues to be fuelled from the perspective of developing multifunctional devices. Here we design a single-phase multiferroic La0.67Sr0.33MnO3-BaTiO3 film, which possesses epitaxial single-crystal and solid-solution structure, high magnetic Curie temperature (~640 K) as well as switchable ferroelectric polarization. Moreover, a notable strain-mediated magnetoelectric coupling at room temperature in the way of modulating the magnetism with an external applied voltage is also observed. The synthetic solid-solution multiferroic film may open an extraordinary avenue for exploring a series of room-temperature multiferroic materials.

  4. Complex hydrides as room-temperature solid electrolytes for rechargeable batteries

    NASA Astrophysics Data System (ADS)

    de Jongh, P. E.; Blanchard, D.; Matsuo, M.; Udovic, T. J.; Orimo, S.

    2016-03-01

    A central goal in current battery research is to increase the safety and energy density of Li-ion batteries. Electrolytes nowadays typically consist of lithium salts dissolved in organic solvents. Solid electrolytes could facilitate safer batteries with higher capacities, as they are compatible with Li-metal anodes, prevent Li dendrite formation, and eliminate risks associated with flammable organic solvents. Less than 10 years ago, LiBH4 was proposed as a solid-state electrolyte. It showed a high ionic conductivity, but only at elevated temperatures. Since then a range of other complex metal hydrides has been reported to show similar characteristics. Strategies have been developed to extend the high ionic conductivity of LiBH4 down to room temperature by partial anion substitution or nanoconfinement. The present paper reviews the recent developments in complex metal hydrides as solid electrolytes, discussing in detail LiBH4, strategies towards for fast room-temperature ionic conductors, alternative compounds, and first explorations of implementation of these electrolytes in all-solid-state batteries.

  5. Reversible Photoswitching of a Spin-Crossover Molecular Complex in the Solid State at Room Temperature.

    PubMed

    Rösner, Benedikt; Milek, Magdalena; Witt, Alexander; Gobaut, Benoît; Torelli, Piero; Fink, Rainer H; Khusniyarov, Marat M

    2015-10-26

    Spin-crossover metal complexes are highly promising magnetic molecular switches for prospective molecule-based devices. The spin-crossover molecular photoswitches developed so far operate either at very low temperatures or in the liquid phase, which hinders practical applications. Herein, we present a molecular spin-crossover iron(II) complex that can be switched between paramagnetic high-spin and diamagnetic low-spin states with light at room temperature in the solid state. The reversible photoswitching is induced by alternating irradiation with ultraviolet and visible light and proceeds at the molecular level. PMID:26480333

  6. Chain and conformation stability of solid-state DNA: implications for room temperature storage

    PubMed Central

    Bonnet, Jacques; Colotte, Marthe; Coudy, Delphine; Couallier, Vincent; Portier, Joseph; Morin, Bénédicte; Tuffet, Sophie

    2010-01-01

    There is currently wide interest in room temperature storage of dehydrated DNA. However, there is insufficient knowledge about its chemical and structural stability. Here, we show that solid-state DNA degradation is greatly affected by atmospheric water and oxygen at room temperature. In these conditions DNA can even be lost by aggregation. These are major concerns since laboratory plastic ware is not airtight. Chain-breaking rates measured between 70°C and 140°C seemed to follow Arrhenius’ law. Extrapolation to 25°C gave a degradation rate of about 1–40 cuts/105 nucleotides/century. However, these figures are to be taken as very tentative since they depend on the validity of the extrapolation and the positive or negative effect of contaminants, buffers or additives. Regarding the secondary structure, denaturation experiments showed that DNA secondary structure could be preserved or fully restored upon rehydration, except possibly for small fragments. Indeed, below about 500 bp, DNA fragments underwent a very slow evolution (almost suppressed in the presence of trehalose) which could end in an irreversible denaturation. Thus, this work validates using room temperature for storage of DNA if completely protected from water and oxygen. PMID:19969539

  7. Preparation of Soft Magnetic Fe-Ni-Pb-B Alloy Nanoparticles by Room Temperature Solid-Solid Reaction

    PubMed Central

    Zhong, Qin

    2013-01-01

    The Fe-Ni-Pb-B alloy nanoparticles was prepared by a solid-solid chemical reaction of ferric trichloride, nickel chloride, lead acetate, and potassium borohydride powders at room temperature. The research results of the ICP and thermal analysis indicate that the resultants are composed of iron, nickel, lead, boron, and PVP, and the component of the alloy is connected with the mole ratio of potassium borohydride and the metal salts. The TEM images show that the resultants are ultrafine and spherical particles, and the particle size is about a diameter of 25 nm. The largest saturation magnetization value of the 21.18 emu g−1 is obtained in the Fe-Ni-Pb-B alloy. The mechanism of the preparation reaction for the Fe-Ni-Pb-B multicomponent alloys is discussed. PMID:24348196

  8. Preparation of soft magnetic Fe-Ni-Pb-B alloy nanoparticles by room temperature solid-solid reaction.

    PubMed

    Zhong, Guo-Qing; Zhong, Qin

    2013-01-01

    The Fe-Ni-Pb-B alloy nanoparticles was prepared by a solid-solid chemical reaction of ferric trichloride, nickel chloride, lead acetate, and potassium borohydride powders at room temperature. The research results of the ICP and thermal analysis indicate that the resultants are composed of iron, nickel, lead, boron, and PVP, and the component of the alloy is connected with the mole ratio of potassium borohydride and the metal salts. The TEM images show that the resultants are ultrafine and spherical particles, and the particle size is about a diameter of 25 nm. The largest saturation magnetization value of the 21.18 emu g(-1) is obtained in the Fe-Ni-Pb-B alloy. The mechanism of the preparation reaction for the Fe-Ni-Pb-B multicomponent alloys is discussed. PMID:24348196

  9. Advances in room-temperature solid-state gamma-ray spectrometry

    SciTech Connect

    Iwanczyk, J.S.

    1983-01-01

    This article presents a review and analysis of different concepts of gamma-ray spectrometry using room-temperature solid-state detectors. The classical approach involving the use of a charge-sensitive preamplifier and attempting to collect all the ionization charge produced by the gamma ray is analyzed and discussed in terms of the charge transport parameters of the most promising compound semiconductor materials. It is concluded that compound semiconductor detector materials having a large disparity between the ..mu.. tau products for electrons and holes (such as HgI/sub 2/ and CdTe) will have rather poor energy resolution if the classical method of spectrometry requiring full charge collection is employed. 30 references.

  10. Spontaneous formation of crystalline lithium molybdate from solid reagents at room temperature.

    PubMed

    Yip, Thomas W S; Cussen, Edmund J; Wilson, Claire

    2010-01-14

    Lithium molybdate has been prepared by grinding LiOH x H(2)O with MoO(3) in air at room temperature. X-Ray powder diffraction data show that the formation of highly crystalline Li(2)MoO(4) is largely complete after 10 min. The phenacite structure of this material is the same as that derived from an X-ray diffraction study of a single crystal obtained from aqueous solution [R3; a = 14.3178(14) A, c = 9.5757(9) A]. Anhydrous lithium hydroxide fails to give the same reaction indicating that the water of crystallisation of LiOH x H(2)O is a vital component in this rapid synthesis. Differential scanning calorimetry measurements show that this reaction can proceed spontaneously between the two stable solid reagents at sub-ambient temperatures and is driven by the liberation of water from the crystalline lattice. Lithium molybdate prepared in this manner has significantly smaller and more regularly shaped particles than samples prepared by other synthetic methods. PMID:20023976

  11. A NEW SAMPLE CELL DESIGN FOR STUDYING SOLID-MATRIX ROOM TEMPERATURE PHOSPHORESCENCE MOISTURE QUENCHING. (R824100)

    EPA Science Inventory

    A new sample chamber was developed that can be used in the measurement of the effects of moisture on the room-temperature solid-matrix phosphorescence of phosphors adsorbed onto filter paper. The sample chamber consists of a sealed quartz cell that contains a special teflon sampl...

  12. Slow and Fast Light in Room Temperature Solids: Fundamentals and Applications

    NASA Astrophysics Data System (ADS)

    Boyd, Robert W.

    2004-03-01

    In recent years there has been great interest in techniques that can lead to a modification of the propagation velocity of light pulses through optical materials. Interest stems both from the intrinsic interest in the ability to control the velocity of light over large ranges and from the potential for applications such as controllable delay lines, optical data storage devices, optical memories, and devices for quantum information. Matthew Bigelow, Nick Lepeshkin, and I have recently developed a new method for achieving ultra-slow light propagation in room temperature solids. Our method makes use of an effect known as coherent population oscillations. In particular, we apply pump and probe fields to a ruby crystal, and the population of ground-state chromium ions is induced to oscillate coherently at the resulting beat frequency. These oscillations lead to a decreased absorption of the probe beam, and consequently (by the Kramers-Kronig relations) to a steep variation of the refractive index. In our laboratory studies of this effect, we observed reduced light velocities with light speeds as low as 57 m/s. We have also studied light propagation in the reverse saturable absorber alexandrite. In this case, the sign of the effect is inverted, leading to superluminal (but causal) light propagation.

  13. Performance evaluation of ZnO–CuO hetero junction solid state room temperature ethanol sensor

    SciTech Connect

    Yu, Ming-Ru; Suyambrakasam, Gobalakrishnan; Wu, Ren-Jang; Chavali, Murthy

    2012-07-15

    Graphical abstract: Sensor response (resistance) curves of time were changed from 150 ppm to 250 ppm alcohol concentration of ZnO–CuO 1:1. The response and recovery times were measured to be 62 and 83 s, respectively. The sensing material ZnO–CuO is a high potential alcohol sensor which provides a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature. Highlights: ► The main advantages of the ethanol sensor are as followings. ► Novel materials ZnO–CuO ethanol sensor. ► The optimized ZnO–CuO hetero contact system. ► A good sensor response and room working temperature (save energy). -- Abstract: A semiconductor ethanol sensor was developed using ZnO–CuO and its performance was evaluated at room temperature. Hetero-junction sensor was made of ZnO–CuO nanoparticles for sensing alcohol at room temperature. Nanoparticles were prepared by hydrothermal method and optimized with different weight ratios. Sensor characteristics were linear for the concentration range of 150–250 ppm. Composite materials of ZnO–CuO were characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR) and high-resolution transmission electron microscopy (HR-TEM). ZnO–CuO (1:1) material showed maximum sensor response (S = R{sub air}/R{sub alcohol}) of 3.32 ± 0.1 toward 200 ppm of alcohol vapor at room temperature. The response and recovery times were measured to be 62 and 83 s, respectively. The linearity R{sup 2} of the sensor response was 0.9026. The sensing materials ZnO–CuO (1:1) provide a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature.

  14. Superluminal and Ultra-Slow Light Propagation in Room-Temperature Solids

    NASA Astrophysics Data System (ADS)

    Boyd, Robert W.; Bigelow, Matthew S.; Lepeshkin, Nick N.

    2004-12-01

    We have observed ultra-slow light propagation (57 m s-1) in ruby and superluminal (-800 m s-1) light propagation in alexandrite at room temperature. The modified light speed results from the rapid variation in refractive index associated with spectral holes and antiholes produced by the process of coherent population oscillations.

  15. Superluminal and slow light propagation in a room-temperature solid.

    PubMed

    Bigelow, Matthew S; Lepeshkin, Nick N; Boyd, Robert W

    2003-07-11

    We have observed both superluminal and ultraslow light propagation in an alexandrite crystal at room temperature. Group velocities as slow as 91 meters per second to as fast as -800 meters per second were measured and attributed to the influence of coherent population oscillations involving chromium ions in either mirror or inversion sites within the crystal lattice. Namely, ions in mirror sites are inversely saturable and cause superluminal light propagation, whereas ions in inversion sites experience conventional saturable absorption and produce slow light. This technique for producing large group indices is considerably easier than the existing methods to implement and is therefore suitable for diverse applications. PMID:12855803

  16. Solvent permits solid curing agents to be used at room temperatures

    NASA Technical Reports Server (NTRS)

    St. Cyr, M. C.

    1967-01-01

    Solvent system dissolves the solid curing agents used with polyurethane resins in adhesive systems. The system developed yields bond strengths comparable to 100 percent solid formulations. The optimum solvent chosen was a 55.5 percent solution in anhydrous tetrahydrofuran.

  17. A study of room-temperature LixMn1.5Ni0.5O4 solid solutions

    DOE PAGESBeta

    Saravanan, Kuppan; Jarry, Angelique; Kostecki, Robert; Chen, Guoying

    2015-01-26

    Understanding the kinetic implication of solid-solution vs. biphasic reaction pathways is critical for the development of advanced intercalation electrode materials. Yet this has been a long-standing challenge in materials science due to the elusive metastable nature of solid solution phases. The present study reports the synthesis, isolation, and characterization of room-temperature LixMn1.5Ni0.5O4 solid solutions. In situ XRD studies performed on pristine and chemically-delithiated, micron-sized single crystals reveal the thermal behavior of LixMn1.5Ni0.5O4 (0 ≤ x ≤ 1) cathode material consisting of three cubic phases: LiMn1.5Ni0.5O4 (Phase I), Li0.5Mn1.5Ni0.5O4 (Phase II) and Mn1.5Ni0.5O4 (Phase III). A phase diagram capturing the structuralmore » changes as functions of both temperature and Li content was established. In conclusion, the work not only demonstrates the possibility of synthesizing alternative electrode materials that are metastable in nature, but also enables in-depth evaluation on the physical, electrochemical and kinetic properties of transient intermediate phases and their role in battery electrode performance.« less

  18. A study of room-temperature LixMn1.5Ni0.5O4 solid solutions

    PubMed Central

    Saravanan, Kuppan; Jarry, Angelique; Kostecki, Robert; Chen, Guoying

    2015-01-01

    Understanding the kinetic implication of solid-solution vs. biphasic reaction pathways is critical for the development of advanced intercalation electrode materials. Yet this has been a long-standing challenge in materials science due to the elusive metastable nature of solid solution phases. The present study reports the synthesis, isolation, and characterization of room-temperature LixMn1.5Ni0.5O4 solid solutions. In situ XRD studies performed on pristine and chemically-delithiated, micron-sized single crystals reveal the thermal behavior of LixMn1.5Ni0.5O4 (0 ≤ x ≤ 1) cathode material consisting of three cubic phases: LiMn1.5Ni0.5O4 (Phase I), Li0.5Mn1.5Ni0.5O4 (Phase II) and Mn1.5Ni0.5O4 (Phase III). A phase diagram capturing the structural changes as functions of both temperature and Li content was established. The work not only demonstrates the possibility of synthesizing alternative electrode materials that are metastable in nature, but also enables in-depth evaluation on the physical, electrochemical and kinetic properties of transient intermediate phases and their role in battery electrode performance. PMID:25619504

  19. Catalytic solid substrate room temperature phosphorimetry for the determination of trace rhamnose based on its condensation reaction with calcein

    NASA Astrophysics Data System (ADS)

    Liu, Jia-Ming; Lin, Li-Ping; Wang, Hong-Xin; Lin, Shao-Qin; Zhang, Li-Hong; Cai, Wen-Lian; Lin, Xuan; Pan, You-Zhu; Wang, Xin-Xing; Li, Zhi-Ming; Jiao, Li; Cui, Ma-Lin

    2011-12-01

    Calcein (R) could not only emit strong and stable room temperature phosphorescence (RTP) on filter paper using I - as perturber, but also could be oxidized by H 2O 2 to form a non-phosphorescence compound (R'), resulting in the quenching of RTP signal of R. Moreover, the ortho-hydrogen of phenolic hydroxyl in R took condensation reaction with rhamnose (Rha) to produce non-phosphorescence compound (R-Rha) causing the RTP signal of R to further quench, and R-Rha was oxidized by H 2O 2 to form R' and Rha, bringing about the sharp RTP signal quenching of R. Thus, a new solid substrate room temperature phosphorimetry (SSRTP) for the determination of trace Rha based on its strong catalytic effect on H 2O 2 oxidizing R has been established, with the detection limit (LD) of 7.8 zg spot -1 (corresponding concentration: 2.0 × 10 -17 g ml -1, sample volume: 0.40 μl spot -1). This method has been applied to determine trace Rha in cigarettes and jujubes, with the results coinciding well with those determined by a high performance liquid chromatography (HPLC). The component of R-Rha also was analyzed by means of HPLC, mass spectrometer and nuclear magnetic resonance (NMR) measurements. The mechanism of catalytic SSRTP for the determination of trace Rha was discussed.

  20. New room temperature high resolution solid-state detector (CdZnTe) for hard x rays and gamma rays

    NASA Technical Reports Server (NTRS)

    Stewart, Amyelizabeth C.; Desai, Upendra D.

    1993-01-01

    The new CdZnTe high 'Z' material represents a significant improvement in detectors for high energy photons. With the thicknesses available, photons up to 100 keV can be efficiently detected. This material has a wide band gap of 1.5 - 2.2 eV which allows it to operate at room temperature while providing high spectral resolution. Results of resolution evaluations are presented. This detector can be used for high resolution spectral measurements of photons in x-ray and gamma-ray astronomy, offering a significant reduction in the weight, power, and volume of the detector system compared to more conventional detector types such as scintillation counters. In addition, the detector will have the simplicity and reliability of solid-state construction. The CdZnTe detector, as a new development, has not yet been evaluated in space. The Get Away Special program can provide this opportunity.

  1. Analytical and mechanistic aspects of the room temperature phosphorescence of Erythrosine B adsorbed on solid supports as oxygen sensing phases

    NASA Astrophysics Data System (ADS)

    Velasco-García, Nieves; Pereiro-García, Rosario; Diaz-García, Marta E.

    1995-05-01

    Room temperature phosphorescence (RTP) lifetime measurements and spectra of different concentrations of Erythrosine B immobilized on anion exchangers and non-ionic resins have been employed to unveil mechanistic aspects of the RTP of immobilized Erythrosine B. The existence of a definite number of RTP decaying components in some experimental conditions has been confirmed. The effects of humidified argon and air on RTP lifetimes and the changes in luminescence intensities were used to investigate some of the interactions responsible for the multiple component RTP emission. The experiments performed also proved the suitability of the phases prepared using non-ionic resins, for the quantification of molecular oxygen by RTP-quenching measurements. Moreover, the solid phases with anion-exchanger resins showed good potential for the analytical sensing of humidity.

  2. A novel optical biosensor for direct and selective determination of serotonin in serum by Solid Surface-Room Temperature Phosphorescence.

    PubMed

    Ramon-Marquez, Teresa; Medina-Castillo, Antonio L; Fernandez-Gutierrez, Alberto; Fernandez-Sanchez, Jorge F

    2016-08-15

    This paper describes a novel biosensor which combines the use of nanotechnology (non-woven nanofibre mat) with Solid Surface-Room Temperature Phosphorescence (SS-RTP) measurement for the determination of serotonin in human serum. The developed biosensor is simple and can be directly applied in serum; only requires a simple clean-up protocol. Therefore it is the first time that serotonin is analysed directly in serum with a non-enzymatic technique. This new approach is based on the covalent immobilization of serotonin directly from serum on a functional nanofibre material (Tiss®-Link) with a preactivated surface for direct covalent immobilization of primary and secondary amines, and the subsequent measurement of serotonin phosphorescent emission from the solid surface. The phosphorescent detection allows avoiding the interference from any fluorescence emission or scattering light from any molecule present in the serum sample which can be also immobilised on the nanofibre material. The determination of serotonin with this SS-RTP sensor overcomes some limitations, such as large interference from the matrix and high cost and complexity of many of the methods widely used for serotonin analysis. The potential applicability of the sensor in the clinical diagnosis was demonstrated by analysing serum samples from seven healthy volunteers. The method was validated with an external reference laboratory, obtaining a correlation coefficient of 0.997 which indicates excellent correlation between the two methods. PMID:27085954

  3. Orthogonal optimization for room temperature magnetron sputtering of ZnO:Al films for all-solid electrochromic devices

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Diao, Xungang; Ding, Peng

    2011-02-01

    In order to obtain competent and quality (high transparency, conductivity and stability) aluminium-doped zinc oxide (ZnO:Al, ZAO) films for all solid electrochromic devices, ZAO films were prepared by direct current (D.C.) reactive magnetron sputtering at room temperature based on orthogonal design. Optical and electrical property dependences of the films on the four dominant sputtering parameters: sputtering time, target-substrate distance, sputtering power and O2 flow ratio were simultaneously investigated with measured results using mathematical and statistical method. Optimal Parameters to fabricate ZAO films with optimum comprehensive performances were obtained ultimately. Resistivity and carrier concentration of ZAO film deposited with optimized parameters were 3.89 × 10-4 Ω cm and 1.09 × 1021 cm-3, respectively. ZAO films with these superior properties were employed as transparent electrodes eventually in a WO3 based all-solid electrochromic device which displayed good electrochromic performance. The regulation range for transmittance in the visible region of the device was more than 50%, which was comparable to that of the device adopting indium tin oxide (ITO) films as electrodes.

  4. Room temperature high-fidelity holonomic single-qubit gate on a solid-state spin

    PubMed Central

    Arroyo-Camejo, Silvia; Lazariev, Andrii; Hell, Stefan W.; Balasubramanian, Gopalakrishnan

    2014-01-01

    At its most fundamental level, circuit-based quantum computation relies on the application of controlled phase shift operations on quantum registers. While these operations are generally compromised by noise and imperfections, quantum gates based on geometric phase shifts can provide intrinsically fault-tolerant quantum computing. Here we demonstrate the high-fidelity realization of a recently proposed fast (non-adiabatic) and universal (non-Abelian) holonomic single-qubit gate, using an individual solid-state spin qubit under ambient conditions. This fault-tolerant quantum gate provides an elegant means for achieving the fidelity threshold indispensable for implementing quantum error correction protocols. Since we employ a spin qubit associated with a nitrogen-vacancy colour centre in diamond, this system is based on integrable and scalable hardware exhibiting strong analogy to current silicon technology. This quantum gate realization is a promising step towards viable, fault-tolerant quantum computing under ambient conditions. PMID:25216026

  5. Room temperature high-fidelity holonomic single-qubit gate on a solid-state spin.

    PubMed

    Arroyo-Camejo, Silvia; Lazariev, Andrii; Hell, Stefan W; Balasubramanian, Gopalakrishnan

    2014-01-01

    At its most fundamental level, circuit-based quantum computation relies on the application of controlled phase shift operations on quantum registers. While these operations are generally compromised by noise and imperfections, quantum gates based on geometric phase shifts can provide intrinsically fault-tolerant quantum computing. Here we demonstrate the high-fidelity realization of a recently proposed fast (non-adiabatic) and universal (non-Abelian) holonomic single-qubit gate, using an individual solid-state spin qubit under ambient conditions. This fault-tolerant quantum gate provides an elegant means for achieving the fidelity threshold indispensable for implementing quantum error correction protocols. Since we employ a spin qubit associated with a nitrogen-vacancy colour centre in diamond, this system is based on integrable and scalable hardware exhibiting strong analogy to current silicon technology. This quantum gate realization is a promising step towards viable, fault-tolerant quantum computing under ambient conditions. PMID:25216026

  6. SEPARATION AND CHARACTERIZATION OF TETROL METABOLITES OF BENZO[A]PYRENE-DNA ADDUCTS USING HPLC AND SOLID-MATRIX ROOM TEMPERATURE LUMINESCENCE. (R824100)

    EPA Science Inventory

    Abstract

    Four tetrols of benzo[a]pyrene-DNA adducts were separated using reversed-phase high performance liquid chromatography. Chromatographic fractions containing a given tetrol were readily characterized with solid-matrix room temperature luminescence techniques. So...

  7. Room temperature sputtering of inclined c-axis ZnO for shear mode solidly mounted resonators

    NASA Astrophysics Data System (ADS)

    Rughoobur, G.; DeMiguel-Ramos, M.; Mirea, T.; Clement, M.; Olivares, J.; Díaz-Durán, B.; Sangrador, J.; Miele, I.; Milne, W. I.; Iborra, E.; Flewitt, A. J.

    2016-01-01

    ZnO films with a c-axis significantly inclined away from the surface normal were grown by a remote plasma sputtering technique at room temperature. The films were used to make solidly mounted resonators (SMRs) operating in shear mode at a resonant frequency of 1.35 GHz. Control of the ZnO microstructure was achieved using a polycrystalline AlN seed layer which can be added on top of a sputtered acoustic mirror to give a complete SMR device. The ZnO was reactively sputtered in an atmosphere of argon and oxygen from a zinc target. The c-axis of the ZnO was estimated to be at an angle of ˜45° to the surface normal. SMRs were measured to have quality factors (Q) of up to 140 and effective electromechanical coupling coefficients of up to 2.2% in air. Although an inclined c-axis can be achieved with direct growth onto the acoustic mirror, it is shown that the AlN seed layer provides higher coupling coefficients and narrower inclination angular distribution. The responses of the devices in liquids of different viscosities (acetone, water, and AZ5214E photoresist) were measured. The shear mode Q decreased by 45% in acetone, 72% in water, and 92% in AZ5214E.

  8. Manipulation of Zeeman coherence in solids at room temperature: Ramsey interference in the coherent-population-trapping spectrum of ruby

    SciTech Connect

    Kolesov, Roman; Scully, Marlan O.; Kocharovskaya, Olga

    2006-11-15

    Coherent population trapping (CPT) in a three-level atomic medium pumped by two subsequent short optical pulses is considered under the condition of negligible population decay from the excited optical state. It is shown that the amount of atomic population transferred to the excited state by the combined action of the pulses strongly depends on the phase of the ground-state coherence excited by the first pulse at the arrival time of the second pulse. Oscillatory behavior of optical excitation efficiency on the time delay between the pulses is predicted. It is also shown that saturating optical pulses can produce population inversion in a resonantly pumped quasi-two-level system. A class of solid materials in which the predicted phenomena can be observed at room temperature is found. It includes some rare-earth and transition-metal doped dielectric crystals where Orbach relaxation between ground-state Zeeman states is suppressed: ruby, alexandrite, and several others. On the basis of the theoretical predictions, experimental observation of Ramsey fringes in CPT spectrum of ruby is reported.

  9. Manipulation of Zeeman coherence in solids at room temperature: Ramsey interference in the coherent-population-trapping spectrum of ruby

    NASA Astrophysics Data System (ADS)

    Kolesov, Roman; Scully, Marlan O.; Kocharovskaya, Olga

    2006-11-01

    Coherent population trapping (CPT) in a three-level atomic medium pumped by two subsequent short optical pulses is considered under the condition of negligible population decay from the excited optical state. It is shown that the amount of atomic population transferred to the excited state by the combined action of the pulses strongly depends on the phase of the ground-state coherence excited by the first pulse at the arrival time of the second pulse. Oscillatory behavior of optical excitation efficiency on the time delay between the pulses is predicted. It is also shown that saturating optical pulses can produce population inversion in a resonantly pumped quasi-two-level system. A class of solid materials in which the predicted phenomena can be observed at room temperature is found. It includes some rare-earth and transition-metal doped dielectric crystals where Orbach relaxation between ground-state Zeeman states is suppressed: ruby, alexandrite, and several others. On the basis of the theoretical predictions, experimental observation of Ramsey fringes in CPT spectrum of ruby is reported.

  10. An All-Solid-State, Room-Temperature, Heterodyne Receiver for Atmospheric Spectroscopy at 1.2 THz

    NASA Technical Reports Server (NTRS)

    Siles, Jose V.; Mehdi, Imran; Schlecht, Erich T.; Gulkis, Samuel; Chattopadhyay, Goutam; Lin, Robert H.; Lee, Choonsup; Gill, John J.; Thomas, Bertrand; Maestrini, Alain E.

    2013-01-01

    Heterodyne receivers at submillimeter wavelengths have played a major role in astrophysics as well as Earth and planetary remote sensing. All-solid-state heterodyne receivers using both MMIC (monolithic microwave integrated circuit) Schottky-diode-based LO (local oscillator) sources and mixers are uniquely suited for long-term planetary missions or Earth climate monitoring missions as they can operate for decades without the need for any active cryogenic cooling. However, the main concern in using Schottky-diode-based mixers at frequencies beyond 1 THz has been the lack of enough LO power to drive the devices because 1 to 3 mW are required to properly pump Schottky diode mixers. Recent progress in HEMT- (high-electron-mobility- transistor) based power amplifier technology, with output power levels in excess of 1 W recently demonstrated at W-band, as well as advances in MMIC Schottky diode circuit technology, have led to measured output powers up to 1.4 mW at 0.9 THz. Here the first room-temperature tunable, all-planar, Schottky-diode-based receiver is reported that is operating at 1.2 THz over a wide (˜20%) bandwidth. The receiver front-end (see figure) consists of a Schottky-diode-based 540 to 640 GHz multiplied LO chain (featuring a cascade of W-band power amplifiers providing around 120 to 180 mW at W-band), a 200-GHz MMIC frequency doubler, and a 600-GHz MMIC frequency tripler, plus a biasable 1.2-THz MMIC sub-harmonic Schottky-diode mixer. The LO chain has been designed, fabricated, and tested at JPL and provides around 1 to 1.5 mW at 540 o 640 GHz. The sub-harmonic mixer consists of two Schottky diodes on a thin GaAs membrane in an anti-parallel configuration. An integrated metal insulator metal (MIM) capacitor has been included on-chip to allow dc bias for the Schottky diodes. A bias voltage of around 0.5 V/diode is necessary to reduce the LO power required down to the 1 to 1.5 mW available from the LO chain. The epilayer thickness and doping profiles have

  11. Entangling Macroscopic Diamonds at Room Temperature

    NASA Astrophysics Data System (ADS)

    Lee, K. C.; Sprague, M. R.; Sussman, B. J.; Nunn, J.; Langford, N. K.; Jin, X.-M.; Champion, T.; Michelberger, P.; Reim, K. F.; England, D.; Jaksch, D.; Walmsley, I. A.

    2011-12-01

    Quantum entanglement in the motion of macroscopic solid bodies has implications both for quantum technologies and foundational studies of the boundary between the quantum and classical worlds. Entanglement is usually fragile in room-temperature solids, owing to strong interactions both internally and with the noisy environment. We generated motional entanglement between vibrational states of two spatially separated, millimeter-sized diamonds at room temperature. By measuring strong nonclassical correlations between Raman-scattered photons, we showed that the quantum state of the diamonds has positive concurrence with 98% probability. Our results show that entanglement can persist in the classical context of moving macroscopic solids in ambient conditions.

  12. Synthesis of H(x)Li(1-x)LaTiO4 from quantitative solid-state reactions at room temperature.

    PubMed

    Yip, Thomas W S; Cussen, Edmund J; MacLaren, Donald A

    2010-02-01

    The layered perovskite HLaTiO(4) reacts stoichiometrically with LiOH.H(2)O at room temperature to give targeted compositions in the series H(x)Li(1-x)LaTiO(4). Remarkably, the Li(+) and H(+) ions are quantitatively exchanged in the solid state and this allows stoichiometric control of ion exchange for the first time in this important series of compounds. PMID:20087491

  13. Determination of trace copper by solid substrate-room temperature phosphorescence quenching method based on activating effect of α,α'-dipyridyl on Vitamin C reducing beryllon

    NASA Astrophysics Data System (ADS)

    Ming, Liu Jia; Lin, Xuan; Lin, Hong; Li, Ping Ping; Liu, Hai Zhu; Huang, Jun Li; Lin, Shao Qin

    2006-07-01

    A new solid substrate-room temperature phosphorescence quenching method for the determination of trace copper has been established. It is based on the fact that beryllon (R) can emit strong and stable solid substrate-room temperature phosphorescence on the filter paper, and Vitamin C (Vc) reduces R to non-phosphorescent compound that leads to solid substrate-room temperature phosphorescence (SS-RTP) quenching of R, and α,α'-dipyridyl can activate copper catalyzing Vitamin C reducing R. The Δ Ip of the system with α,α'-dipyridyl is 3.3 times higher than that without α,α'-dipyridyl, which shows the reaction of α,α'-dipyridyl activating copper catalyzing Vitamin C reducing R. The reducing value of phosphorescence intensity (Δ Ip) is directly proportional to the content of Cu(II) in the range of 0.040-4.0 fg spot -1 (corresponding concentration: 0.10-10.0 pg ml -1, sample volume: 0.40 μl spot -1). The regression equation of working curve can be expressed as Δ Ip = 69.99 + 41.00 m Cu 2+ (fg spot -1) ( r = 0.9980, n = 6), and the detection limit is 0.0088 fg spot -1(corresponding concentration: 2.2 × 10 -14 g ml -1). This sensitive and accurate method with good repeatability and high selectivity has been applied to the determination of trace copper in real samples with satisfactory results. The reaction mechanism for the determination of trace copper by solid substrate-room temperature phosphorescence quenching method based on the activating effect of α,α'-dipyridyl on Vitamin C reducing beryllon is also discussed.

  14. Room-temperature luminescence of benzo[f]quinoline, p-aminobenzoic acid, phenanthrene, and 4-phenylphenol on a variety of solid surfaces

    SciTech Connect

    Purdy, B.B.; Hurtubise, R.J. )

    1989-01-01

    Analytical figures of merit for the room-temperature luminescence of four model compounds with quite different chemical structures were compared. The compounds were adsorbed on four different surfaces that have been employed recently in solid-surface luminescence analysis. The solid materials investigated were silica gel with a polyacrylate binder, filter paper, 1% polyacrylic acid-NaBr, and 80% [alpha]-cyclodextrin-NaCl. The experimental conditions were optimized to give enhanced luminescence signals. In some cases, filter paper and 80% [alpha]-cyclodextrin-NaCl gave comparable analytical results. However, filter paper gave the best overall results.

  15. Corneal storage at room temperature.

    PubMed

    Sachs, U; Goldman, K; Valenti, J; Kaufman, H E

    1978-06-01

    Short-term eye banking is based mainly on moist chamber and McCarey-Kaufman medium (M-K medium) preservation. Both involve a controlled 4 C temperature for storage. Warming the cornea to room temperature, however, drastically affects the endothelial viability. On enzymatic staining and histological study, the M-K medium-stored rabbit corneas had more normal endothelium than did "moist chamber" eyes when storage was prolonged for seven days at room temperature. In human corneas that were kept at 4 C for 24 hours and then exposed to a temperature of 25 C, destruction of organelles had occurred by six hours and was increased by 12 hours. Corneas that were kept in M-K medium had relatively intact endothelium after four days, but cell disruption and vacuolation was present by the seventh day. The M-K medium, therefore, affords protection to tissue warmed to room temperature, where metabolic activity is resumed. PMID:350203

  16. A room temperature Na/S battery using a β″ alumina solid electrolyte separator, tetraethylene glycol dimethyl ether electrolyte, and a S/C composite cathode

    NASA Astrophysics Data System (ADS)

    Kim, Icpyo; Park, Jin-Young; Kim, Chang Hyeon; Park, Jin-Woo; Ahn, Jae-Pyoung; Ahn, Jou-Hyeon; Kim, Ki-Won; Ahn, Hyo-Jun

    2016-01-01

    To realize a high-performance room temperature Na/S battery with an elemental sulfur cathode, it is important that sodium polysulfides stay within the cathode and that they have room enough to react freely. In this work, sodium polysulfides are confined to the cathode using a β″ alumina solid electrolyte separator and an optimal amount of tetraethylene glycol dimethyl ether (TEGDME) electrolyte. In addition, an activated carbon material, in the form of a sulfur/carbon (S/C) composite, with high surface area, porosity, and pore volume is employed in the cathode. The resulting Na/S battery shows a high first discharge capacity of 855 mAh g-1 and coulombic efficiency close to 100%, as well as stable cyclability, with a discharge capacity of 521 mAh g-1 at the 104th discharge.

  17. Room temperature terahertz polariton emitter

    SciTech Connect

    Geiser, Markus; Scalari, Giacomo; Castellano, Fabrizio; Beck, Mattias; Faist, Jerome

    2012-10-01

    Terahertz (THz) range electroluminescence from intersubband polariton states is observed in the ultra strong coupling regime, where the interaction energy between the collective excitation of a dense electron gas and a photonic mode is a significant portion of the uncoupled excitation energy. The polariton's increased emission efficiency along with a parabolic electron confinement potential allows operation up to room temperature in a nonresonant pumping scheme. This observation of room temperature electroluminescence of an intersubband device in the THz range is a promising proof of concept for more powerful THz sources.

  18. Room-temperature ferromagnetism of 2H-SiC-α-Al2O3 solid solution nanowires and the physical origin

    NASA Astrophysics Data System (ADS)

    Sun, Yong; Lu, Cheng; Cui, Hao; Wang, Jing; Ma, Yanming; Wang, Chengxin

    2015-03-01

    In this work we report the first synthesis of 2H-SiC-α-Al2O3 solid solution (SS) nanowires with 2H-SiC as the host phase. The one dimensional (1D) fake binary-system exhibits interesting room-temperature ferromagnetism and spin-glass-like (SGL) behavior. This novel diluted magnetic semiconductor (DMS) was designed on the basis of SiC which is the most promising fundamental semiconductor used in next-generation electronics as the substitute for Si. A systematic investigation of the magnetic properties reveals the origin of the material's room-temperature ferromagnetism and spin-glass behavior. Spin-polarized density functional theory (DFT) calculations reveal that the net moment originates from a strong coupling between atoms around local Si vacancies produced by the SS defect reaction. Unlike random defects derived magnetic behavior, the SS resulted magnetism is significant to be utilized in functional devices since it belongs to a stable crystal structure that is possible to be prepared rationally in a controlled manner.In this work we report the first synthesis of 2H-SiC-α-Al2O3 solid solution (SS) nanowires with 2H-SiC as the host phase. The one dimensional (1D) fake binary-system exhibits interesting room-temperature ferromagnetism and spin-glass-like (SGL) behavior. This novel diluted magnetic semiconductor (DMS) was designed on the basis of SiC which is the most promising fundamental semiconductor used in next-generation electronics as the substitute for Si. A systematic investigation of the magnetic properties reveals the origin of the material's room-temperature ferromagnetism and spin-glass behavior. Spin-polarized density functional theory (DFT) calculations reveal that the net moment originates from a strong coupling between atoms around local Si vacancies produced by the SS defect reaction. Unlike random defects derived magnetic behavior, the SS resulted magnetism is significant to be utilized in functional devices since it belongs to a stable crystal

  19. Room-temperature solid state synthesis of ZnO/Bi{sub 2}O{sub 3} heterojunction and their solar light photocatalytic performance

    SciTech Connect

    Wang, Xin; Ren, Pengrong; Fan, Huiqing

    2015-04-15

    Highlights: • ZnO/Bi{sub 2}O{sub 3} hierarchical nanostructures were synthesized via a solid-state reaction. • The amount of Bi{sub 2}O{sub 3} plays an important role in controlling the morphology. • The amount of Bi{sub 2}O{sub 3} plays an important role in controlling the photocatalysis. - Abstract: ZnO/Bi{sub 2}O{sub 3} heterojunction was prepared by solid state reaction method at room temperature. The as-prepared nanostructures were characterized as the assembled nanosheets of ZnO on which Bi{sub 2}O{sub 3} nanoparticles were well dispersed. Further studies revealed that the morphology and photocatalytic property could be regulated by tuning the amount of Bi{sub 2}O{sub 3}. The introduction of Bi{sub 2}O{sub 3} can lead to the enhancement of solar light absorption, and the 5% ZnO/Bi{sub 2}O{sub 3} samples exhibited the best photocatalytic activity under the solar light irradiation. The excellent photocatalytic performances could be ascribed to the synergistic effects of the hierarchical nanostructures and the effective separation of photogenerated carriers. Moreover, the hydroxyl radicals (·OH) are found to be the main active species generated in the oxidation reaction of RhB over ZnO/Bi{sub 2}O{sub 3} photocatalyst. Therefore, our work demonstrated a facile way to prepare hierarchical nanostructures with excellent photocatalytic performance using solid state method at room temperature.

  20. Investigation of the room-temperature solid-state reactions leading to ZnS nanotubes and the third-order nonlinear optical properties of the nanotubes obtained

    NASA Astrophysics Data System (ADS)

    Zhou, Tao-Yu; Song, Ying-Lin; Hong, Jian-Ming; Xin, Xin-Quan

    2005-04-01

    The room-temperature solid-state reactions occurring in the preparation of nanotubes of zinc sulfide are further investigated by x-ray powder diffractometry (XRD) and infra-red (IR) spectrometry measurements, and the nanotube ZnS product obtained is measured by Z-scan technology to investigate the third-order nonlinear optical (NLO) properties. The XRD result suggests that the reactions leading to the formation of the nanotubules have occurred through reaction-controlled to growth-controlled procedures, and the IR result indicates that the procedures involve a coordination effect of the additive DABCO as ligand on the reactant. The result of NLO measurements shows that the nanotube ZnS products obtained have the behaviours of the third-order nonlinear optical properties of both NLO absorption and NLO refraction with self-focusing effects.

  1. Novel room temperature ferromagnetic semiconductors

    SciTech Connect

    Gupta, Amita

    2004-11-01

    Today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one 'spintronic' device that exploits both charge and 'spin' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 mu-m thick transparent pulsed laser deposited films of the Mn (<4 at. percent) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous distribution of Mn substituting

  2. Observation of ferromagnetism at room temperature in polycrystalline Zn1 - x Fe x O solid solutions synthesized by the precursor method

    NASA Astrophysics Data System (ADS)

    Krasil'nikov, V. N.; Dyachkova, T. V.; Tyutyunnik, A. P.; Marchenkov, V. V.; Gyrdasova, O. I.; Baklanova, I. V.; Kuznetsov, M. V.; Weber, H. W.

    2015-06-01

    Polycrystalline Zn1 - x Fe x O (0 ≤ x ≤ 0.075) solid solutions with the wurtzite structure, which belong to the class of diluted magnetic semiconductors, have been synthesized by the precursor method using a mixed formate of the composition Zn1 - x Fe x (HCOO)2 · 2H2O as a precursor. It has been found that the iron concentration in Zn1 - x Fe x O solid solutions, which exhibit ferromagnetic properties with a high degree of magnetization at room temperature, is determined by two factors: (1) the degree of substitution of iron for zinc in the structure of zinc formate Zn(HCOO)2 · 2H2O and, therefore, in the structure of zinc oxide ZnO and (2) the conditions of heat treatment of the precursor. It has been shown using samples with x = 0.025 and 0.05 as an example that the magnetization of Zn1 - x Fe x O solid solutions regularly increases with an increase in the iron concentration. Based on the results of the X-ray photoelectron spectroscopy analysis of Zn1 - x Fe x O powders, it has been suggested that the iron concentration increases in the surface layer of particles, and the oxidation state of iron is 3+.

  3. A facile and rapid room-temperature route to hierarchical bismuth oxyhalide solid solutions with composition-dependent photocatalytic activity.

    PubMed

    Zhang, Juan; Han, Qiaofeng; Zhu, Junwu; Wang, Xin

    2016-09-01

    The unique nanosheet-based flower-like BiOCl1-xBrx (x=0-1) hierarchical solid solutions have been prepared by the reaction of Bi2O3 and KCl/KBr in mixed solution of glacial acetic acid (HAc) and H2O in dozens of minutes under ambient conditions. During the preparation process, the intermediate bismuth oxide acetate (CH3COOBiO) plays a key role in the formation of BiOCl1-xBrx solid solutions in such a short time. The as-prepared hierarchical BiOCl1-xBrx solid solutions possess high specific surface areas and modified band structures, which exhibit enhanced photocatalytic activity for Rhodamine B (RhB) degradation in comparison with pure BiOCl and BiOBr under visible light irradiation, with the activity reaching the maximum at x=0.5. The photodegradation efficiency of the BiOCl0.5Br0.5 solid solution is twice and 12times higher than P25 TiO2 under UV and visible light irradiation, respectively. PMID:27236841

  4. Enhanced photoluminescence of SrWO4:Eu3+ red phosphor synthesized by mechanochemically assisted solid state metathesis reaction method at room temperature

    NASA Astrophysics Data System (ADS)

    Peter, Anthuvan John; Banu, I. B. Shameem

    2015-06-01

    Optically efficient europium activated alkaline earth metal tungstate nano phosphor (SrWO4) with different doping concentrations have been synthesized by mechanochemically assisted solid state metathesis reaction at room temperature for the first time. The XRD and Raman spectra results indicated that the prepared powders exhibit a scheelite-type tetragonal structure. FTIR spectra exhibited a high absorption band situated at around 854 cm-1, which was ascribed to the W-O antisymmetric stretching vibrations into the [WO4]2- tetrahedron groups. Analysis of the emission spectra with different Eu3+ concentrations revealed that the optimum dopant concentration for SrWO4: x Eu3+ phosphor is about 8 mol% of Eu3+.The red emission intensity of the SSM prepared SrWO4: 0.08Eu3+ phosphors are 2 times greater than that of the commercial Y2O2S: Eu3+ red phosphor prepared by the conventional solid state reaction method. All the results indicate that the phosphor is a promising red phosphor pumped by NUV InGaN chip for fabricating WLED.

  5. Enhanced photoluminescence of SrWO{sub 4}:Eu{sup 3+} red phosphor synthesized by mechanochemically assisted solid state metathesis reaction method at room temperature

    SciTech Connect

    Peter, Anthuvan John Banu, I. B. Shameem

    2015-06-24

    Optically efficient europium activated alkaline earth metal tungstate nano phosphor (SrWO{sub 4}) with different doping concentrations have been synthesized by mechanochemically assisted solid state metathesis reaction at room temperature for the first time. The XRD and Raman spectra results indicated that the prepared powders exhibit a scheelite-type tetragonal structure. FTIR spectra exhibited a high absorption band situated at around 854 cm{sup −1}, which was ascribed to the W–O antisymmetric stretching vibrations into the [WO{sub 4}]{sup 2−} tetrahedron groups. Analysis of the emission spectra with different Eu{sup 3+} concentrations revealed that the optimum dopant concentration for SrWO{sub 4}: x Eu{sup 3+} phosphor is about 8 mol% of Eu{sup 3+}.The red emission intensity of the SSM prepared SrWO{sub 4}: 0.08Eu{sup 3+} phosphors are 2 times greater than that of the commercial Y{sub 2}O{sub 2}S: Eu{sup 3+} red phosphor prepared by the conventional solid state reaction method. All the results indicate that the phosphor is a promising red phosphor pumped by NUV InGaN chip for fabricating WLED.

  6. Solid-state-reaction synthesis of cotton-like CoB alloy at room temperature as a catalyst for hydrogen generation.

    PubMed

    Wang, Xingpu; Liao, Jinyun; Li, Hao; Wang, Hui; Wang, Rongfang

    2016-08-01

    A novel room-temperature solid-state reaction is developed to synthesize cotton-like CoB alloy (CoBSSR) catalysts with a large specific surface area of 222.4m(2)g(-1). In the hydrolysis of ammonia borane catalyzed by the CoBSSR, the rate of hydrogen generation can reach 68.7mLmin(-1) with a turnover frequency (TOF) value of ca. 6.9Lhydrogenmin(-1)gcatalyst(-1) at 25°C. The TOF value is about 2 times as large as that of CoB alloy prepared by a regular solid-state reaction, which is also much higher than those of the CoB catalysts recently reported in the literature. The activation energy of the hydrolysis of ammonia borane catalyzed by the CoBSSR is as low as 22.78kJmol(-1), hinting that the CoBSSR possesses high catalytic activity, which may be attributed to the large specific surface area and the abundant porous structure. The high catalytic performance, good recoverability and low cost of the CoBSSR enable it to be a promissing catalyst condidate in the hydrolysis of ammonia borane for hydrogen production in commercial application. PMID:27163841

  7. Determination of enrofloxacin by room-temperature phosphorimetry after solid phase extraction on an acrylic polymer sorbent

    NASA Astrophysics Data System (ADS)

    de Souza, Cabrini F.; Martins, Renata K. S.; da Silva, Andrea R.; da Cunha, Alessandra L. M. C.; Aucélio, Ricardo Q.

    A phosphorimetric method was developed to enable the determination of enrofloxacin using photochemical derivatization which was used to both improve detection limits and to minimize the uncertainty of measurements. Phosphorescence was induced on cellulose containing TlNO3. Absolute limit of detection at the ng range and linear analytical response over three orders of magnitude were achieved. A metrological study was made to obtain the combined uncertainty value and to identify that the precision was mainly affected by the changing of substrates when measuring the signal from each replicate. Pharmaceutical formulations containing enrofloxacin were successfully analyzed by the method and the results were similar to the ones achieved using a HPLC method. A solid phase extraction on an acrylic polymer was optimized to separate enrofloxacin from interferents such as diclofenac and other components from biological matrices, which allowed the successful use of the method in urine analysis.

  8. Catalytic solid substrate-room-temperature phosphorimetry detection for trace cadmium with Cd2+ -3.5-generation polyamidoamine dendrimer-Tween-80 complex.

    PubMed

    Liu, Jia-Ming; Wang, Hong-Xin; Lin, Li-Ping; Lin, Shao-Qin; Lin, Xuan; Cai, Wen-Lian; Lin, Chang-Qing; Li, Zhi-Ming

    2012-01-01

    3.5-Generation polyamidoamine dendrimers (3.5-G-D) emitted strong and stable room-temperature phosphorescence (RTP) on filter paper when Pb2+ was used as a heavy atom perturber. The RTP signal of 3.5-G-D was sharply enhanced upon the formation of 3.5-G-D-Tween-80 micelle compound. The complex Cd2+ -3.5-G-D-Tween-80, generated in the coordination reaction between Cd2+ and the tertiary amidocyanogen on the outer layer of 3.5-G-D in 3.5-G-D-Tween-80 micelle compound, could catalyze KBrO3 to oxidize 3.5-G-D in 3.5-G-D-Tween-80, which caused the sharp quenching of the RTP signal of the system. The phosphorescence intensity change (ΔI(p) ) of the system had a linear relationship with the content of Cd2+. Thus a new catalytic solid substrate-room-temperature phosphorimetry (SS-RTP) for the determination of trace cadmium has been established. This highly selective and sensitive method has been applied to determine trace cadmium in biological samples with a limit of detection (LD) of 1.2 ag per spot (when the sample volume was 0.4 μL per spot, the corresponding concentration was 3.0 × 10(-15)  g mL(-1) ), the results agreeing with those obtained by atomic absorption spectrometry. The mechanism of catalytic SS-RTP for the determination of trace cadmium was also discussed. PMID:22021248

  9. Phosphorescence induced by pressure and continuous light irradiation of benzophenone and 4,4`-bis(dimethylamino)benzophenone in solid polymers at room temperature

    SciTech Connect

    Dreger, Z.A.; Lang, J.M.; Drickamer, H.G.

    1996-03-14

    We report efficient room temperature phosphorescence induced by pressure (PIP) and/or by continuous light irradiation (light-induced phosphorescence (LIP)) in two ketones: benzophenone (BP) and its p-dimethylamino-substituted (Michler`s ketone (MK)) both dissolved in solid poly(ethyl methacrylate) (PEMA). Under pressure both BP and MK reveal a remarkable growth of the phosphorescence intensity: 2 orders of magnitude (within 5 kbar) and 1 order of magnitude (within 50 kbar) respectively for MK and BP. For MK, above 5 kbar the phosphorescence intensity significantly decreases, but for BP the decrease is negligible even above 50 kbar. A model based on the increase of the amount of {pi},{pi}{sup *} character in the predominately n,{pi}{sup *} triplet state with increasing pressure is proposed to account for the observed features of the PIP. The LIP occurs only at pressures below the maximum in the PIP. With prolonged irradiation, the overall shape of the phosphorescence intensity curve versus time depends on pressure, exciting light intensity, and concentration. A tentative explanation of the LIP effect is given that assumes a creation of the phosphorescent photoproduct via the hydrogen abstraction reaction. 36 refs., 14 figs.

  10. In Situ Synthesis of Porous Carbons by Using Room-Temperature, Atmospheric-Pressure Dielectric Barrier Discharge Plasma as High-Performance Adsorbents for Solid-Phase Microextraction.

    PubMed

    Lin, Yao; Wu, Li; Xu, Kailai; Tian, Yunfei; Hou, Xiandeng; Zheng, Chengbin

    2015-09-21

    A one-step, template-free method is described to synthesize porous carbons (PCs) in situ on a metal surface by using a room-temperature, atmospheric-pressure dielectric barrier discharge (DBD) plasma. This method not only features high efficiency, environmentally friendliness, and low cost and simple equipment, but also can conveniently realize large-area synthesis of PCs by only changing the design of the DBD reactor. The synthesized PCs have a regulated nestlike morphology, and thus, provide a high specific surface area and high pore volume, which result in excellent adsorption properties. Its applicability was demonstrated by using a PC-coated stainless-steel fiber as a solid-phase microextraction (SPME) fiber to preconcentrate polycyclic aromatic hydrocarbons (PAHs) prior to analysis by gas chromatography with flame ionization detection (GC-FID). The results showed that the fiber exhibited excellent enrichment factors (4.1×10(4) to 3.1×10(5)) toward all tested PAHs. Thus, the PC-based SPME-GC-FID provides low limits of detection (2 to 20 ng L(-1)), good precision (<7.8%), and good recoveries (80-115%) for ultra-sensitive determination of PAHs in real water samples. In addition, the PC-coated fiber could be stable enough for more than 500 replicate extraction cycles. PMID:26267394

  11. Xenon porometry at room temperature

    NASA Astrophysics Data System (ADS)

    Telkki, Ville-Veikko; Lounila, Juhani; Jokisaari, Jukka

    2006-01-01

    Xenon porometry is a method in which porous material is immersed in a medium and the properties of the material are studied by means of Xe129 nuclear magnetic resonance (NMR) of xenon gas dissolved in the medium. For instance, the chemical shift of a particular signal (referred to as signal D) arising from xenon inside small pockets formed in the pores during the freezing of the confined medium is highly sensitive to the pore size. In the present study, we show that when naphthalene is used as the medium the pore size distribution of the material can be determined by measuring a single one-dimensional spectrum near room temperature and converting the chemical shift scale of signal D to the pore radius scale by using an experimentally determined correlation. A model has been developed that explains the curious behavior of the chemical shift of signal D as a function of pore radius. The other signals of the spectra measured at different temperatures have also been identified, and the influence of xenon pressure on the spectra has been studied. For comparison, Xe129 NMR spectra of pure xenon gas adsorbed to porous materials have been measured and analyzed.

  12. Room temperature synthesis and solid-state structure of Ni{sub 2}P{sub 2}O{sub 6}.12H{sub 2}O

    SciTech Connect

    Haag, J.M.; LeBret, G.C.; Cleary, D.A. . E-mail: cleary@gonzaga.edu; Twamley, B.

    2005-04-15

    The synthesis and crystal structure of Ni{sub 2}P{sub 2}O{sub 6}.12H{sub 2}O are reported. The compound was synthesized from aqueous solutions of nickel chloride and sodium hypodiphosphate at room temperature. The space group is orthorhombic, Pnnm. Unit cell dimensions are a=11.2418(5)A, b=18.5245(8)A, and c=7.3188(3)A, Z=4. The product is unstable with respect to dehydration above room temperature.

  13. Topological Insulators at Room Temperature

    SciTech Connect

    Zhang, Haijun; Liu, Chao-Xing; Qi, Xiao-Liang; Dai, Xi; Fang, Zhong; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-25

    Topological insulators are new states of quantum matter with surface states protected by the time-reversal symmetry. In this work, we perform first-principle electronic structure calculations for Sb{sub 2}Te{sub 3}, Sb{sub 2}Se{sub 3}, Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} crystals. Our calculations predict that Sb{sub 2}Te{sub 3}, Bi{sub 2}T e{sub 3} and Bi{sub 2}Se{sub 3} are topological insulators, while Sb{sub 2}Se{sub 3} is not. In particular, Bi{sub 2}Se{sub 3} has a topologically non-trivial energy gap of 0.3eV , suitable for room temperature applications. We present a simple and unified continuum model which captures the salient topological features of this class of materials. These topological insulators have robust surface states consisting of a single Dirac cone at the {Lambda} point.

  14. Room-temperature stabilization of nanoscale superionic Ag2Se

    NASA Astrophysics Data System (ADS)

    Hu, T.; Wittenberg, J. S.; Lindenberg, A. M.

    2014-10-01

    Superionic materials are multi-component solids in which one sub-lattice exhibits high ionic conductivity within a fixed crystalline structure. This is typically associated with a structural phase transition occurring significantly above room temperature. Here, through combined temperature-resolved x-ray diffraction and differential scanning calorimetry, we map out the nanoscale size-dependence of the Ag2Se tetragonal to superionic phase transition temperature and determine the threshold size for room-temperature stabilization of superionic Ag2Se. For the first time, clear experimental evidence for such stabilization of the highly ionic conducting phase at room temperature is obtained in ˜2 nm diameter spheres, which corresponds to a >100 °C suppression of the bulk phase transition temperature. This may enable technological applications of Ag2Se in devices where high ionic conductivity at room temperature is required.

  15. Room-temperature stabilization of nanoscale superionic Ag₂Se.

    PubMed

    Hu, T; Wittenberg, J S; Lindenberg, A M

    2014-10-17

    Superionic materials are multi-component solids in which one sub-lattice exhibits high ionic conductivity within a fixed crystalline structure. This is typically associated with a structural phase transition occurring significantly above room temperature. Here, through combined temperature-resolved x-ray diffraction and differential scanning calorimetry, we map out the nanoscale size-dependence of the Ag₂Se tetragonal to superionic phase transition temperature and determine the threshold size for room-temperature stabilization of superionic Ag2Se. For the first time, clear experimental evidence for such stabilization of the highly ionic conducting phase at room temperature is obtained in ∼2 nm diameter spheres, which corresponds to a >100 °C suppression of the bulk phase transition temperature. This may enable technological applications of Ag₂Se in devices where high ionic conductivity at room temperature is required. PMID:25249347

  16. Proposal for a room-temperature diamond maser.

    PubMed

    Jin, Liang; Pfender, Matthias; Aslam, Nabeel; Neumann, Philipp; Yang, Sen; Wrachtrup, Jörg; Liu, Ren-Bao

    2015-01-01

    The application of masers is limited by its demanding working conditions (high vacuum or low temperature). A room-temperature solid-state maser is highly desirable, but the lifetimes of emitters (electron spins) in solids at room temperature are usually too short (∼ns) for population inversion. Masing from pentacene spins in p-terphenyl crystals, which have a long spin lifetime (∼0.1 ms), has been demonstrated. This maser, however, operates only in the pulsed mode. Here we propose a room-temperature maser based on nitrogen-vacancy centres in diamond, which features the longest known solid-state spin lifetime (∼5 ms) at room temperature, high optical pumping efficiency (∼10(6) s(-1)) and material stability. Our numerical simulation demonstrates that a maser with a coherence time of approximately minutes is feasible under readily accessible conditions (cavity Q-factor ∼5 × 10(4), diamond size ∼3 × 3 × 0.5 mm(3) and pump power <10 W). A room-temperature diamond maser may facilitate a broad range of microwave technologies. PMID:26394758

  17. Proposal for a room-temperature diamond maser

    NASA Astrophysics Data System (ADS)

    Jin, Liang; Pfender, Matthias; Aslam, Nabeel; Neumann, Philipp; Yang, Sen; Wrachtrup, Jörg; Liu, Ren-Bao

    2015-09-01

    The application of masers is limited by its demanding working conditions (high vacuum or low temperature). A room-temperature solid-state maser is highly desirable, but the lifetimes of emitters (electron spins) in solids at room temperature are usually too short (~ns) for population inversion. Masing from pentacene spins in p-terphenyl crystals, which have a long spin lifetime (~0.1 ms), has been demonstrated. This maser, however, operates only in the pulsed mode. Here we propose a room-temperature maser based on nitrogen-vacancy centres in diamond, which features the longest known solid-state spin lifetime (~5 ms) at room temperature, high optical pumping efficiency (~106 s-1) and material stability. Our numerical simulation demonstrates that a maser with a coherence time of approximately minutes is feasible under readily accessible conditions (cavity Q-factor ~5 × 104, diamond size ~3 × 3 × 0.5 mm3 and pump power <10 W). A room-temperature diamond maser may facilitate a broad range of microwave technologies.

  18. Proposal for a room-temperature diamond maser

    PubMed Central

    Jin, Liang; Pfender, Matthias; Aslam, Nabeel; Neumann, Philipp; Yang, Sen; Wrachtrup, Jörg; Liu, Ren-Bao

    2015-01-01

    The application of masers is limited by its demanding working conditions (high vacuum or low temperature). A room-temperature solid-state maser is highly desirable, but the lifetimes of emitters (electron spins) in solids at room temperature are usually too short (∼ns) for population inversion. Masing from pentacene spins in p-terphenyl crystals, which have a long spin lifetime (∼0.1 ms), has been demonstrated. This maser, however, operates only in the pulsed mode. Here we propose a room-temperature maser based on nitrogen-vacancy centres in diamond, which features the longest known solid-state spin lifetime (∼5 ms) at room temperature, high optical pumping efficiency (∼106 s−1) and material stability. Our numerical simulation demonstrates that a maser with a coherence time of approximately minutes is feasible under readily accessible conditions (cavity Q-factor ∼5 × 104, diamond size ∼3 × 3 × 0.5 mm3 and pump power <10 W). A room-temperature diamond maser may facilitate a broad range of microwave technologies. PMID:26394758

  19. A room-temperature all-solid-state 4.7 THz multiplied LO source to enable the heterodyne observation of interstellar neutral oxygen

    NASA Astrophysics Data System (ADS)

    Siles, Jose

    emission and absorption, the models that predict the chemistry of ISM cannot be verified, revised and/or completed. Until this problem is solved, or in other words, until the fine OI atomic line is observed in high spectral and spatial resolution, the chemistry of oxygen in interstellar clouds and protostellar regions, essential for understanding the formation of stars and the incorporation of key molecules into forming planetary system, will not be fully understood. As a response to this problem, we will develop the first all-solid-state continuous coherent local oscillator (LO) source at 4.7 THz to enable very high-resolution heterodyne observation (R=»/”» > 1E6) of the 4.748 THz (63.1837 μm) fine structure line of neutral atomic oxygen (OI). This source will be broadband, frequency-agile, temperature and frequency stable and will operate at room-temperature (no need of cryogenic cooling). With hot electron bolometer detectors (HEB) already available, the proposed source is the only technological part that is still missing to provide the radio-astronomers with this highly necessary science data for the complete understanding of star and planetary systems formation processes.

  20. Solid-State Dynamic Nuclear Polarization at 9.4 and 18.8 T from 100 K to Room Temperature

    PubMed Central

    2015-01-01

    Efficient dynamic nuclear polarization (DNP) in solids, which enables very high sensitivity NMR experiments, is currently limited to temperatures of around 100 K and below. Here we show how by choosing an adequate solvent, 1H cross effect DNP enhancements of over 80 can be obtained at 240 K. To achieve this we use the biradical TEKPol dissolved in a glassy phase of ortho-terphenyl (OTP). We study the solvent DNP enhancement of both TEKPol and BDPA in OTP in the range from 100 to 300 K at 9.4 and 18.8 T. Surprisingly, we find that the DNP enhancement decreases only relatively slowly for temperatures below the glass transition of OTP (Tg = 243 K), and 1H enhancements around 15–20 at ambient temperature can be observed. We use this to monitor molecular dynamic transitions in the pharmaceutically relevant solids Ambroxol and Ibuprofen. PMID:26555676

  1. Solid-State Dynamic Nuclear Polarization at 9.4 and 18.8 T from 100 K to Room Temperature.

    PubMed

    Lelli, Moreno; Chaudhari, Sachin R; Gajan, David; Casano, Gilles; Rossini, Aaron J; Ouari, Olivier; Tordo, Paul; Lesage, Anne; Emsley, Lyndon

    2015-11-25

    Efficient dynamic nuclear polarization (DNP) in solids, which enables very high sensitivity NMR experiments, is currently limited to temperatures of around 100 K and below. Here we show how by choosing an adequate solvent, (1)H cross effect DNP enhancements of over 80 can be obtained at 240 K. To achieve this we use the biradical TEKPol dissolved in a glassy phase of ortho-terphenyl (OTP). We study the solvent DNP enhancement of both TEKPol and BDPA in OTP in the range from 100 to 300 K at 9.4 and 18.8 T. Surprisingly, we find that the DNP enhancement decreases only relatively slowly for temperatures below the glass transition of OTP (Tg = 243 K), and (1)H enhancements around 15-20 at ambient temperature can be observed. We use this to monitor molecular dynamic transitions in the pharmaceutically relevant solids Ambroxol and Ibuprofen. PMID:26555676

  2. Room temperature creep in metals and alloys

    SciTech Connect

    Deibler, Lisa Anne

    2014-09-01

    Time dependent deformation in the form of creep and stress relaxation is not often considered a factor when designing structural alloy parts for use at room temperature. However, creep and stress relaxation do occur at room temperature (0.09-0.21 Tm for alloys in this report) in structural alloys. This report will summarize the available literature on room temperature creep, present creep data collected on various structural alloys, and finally compare the acquired data to equations used in the literature to model creep behavior. Based on evidence from the literature and fitting of various equations, the mechanism which causes room temperature creep is found to include dislocation generation as well as exhaustion.

  3. Determining Camera Gain in Room Temperature Cameras

    SciTech Connect

    Joshua Cogliati

    2010-12-01

    James R. Janesick provides a method for determining the amplification of a CCD or CMOS camera when only access to the raw images is provided. However, the equation that is provided ignores the contribution of dark current. For CCD or CMOS cameras that are cooled well below room temperature, this is not a problem, however, the technique needs adjustment for use with room temperature cameras. This article describes the adjustment made to the equation, and a test of this method.

  4. Giant electrocaloric effect in ferroelectric nanotubes near room temperature.

    PubMed

    Liu, Man; Wang, Jie

    2015-01-01

    Ferroelectric perovskite oxides possess large electrocaloric effect, but only at high temperature, which limits their potential as next generation solid state cooling devices. Here, we demonstrate from phase field simulations that a giant adiabatic temperature change exhibits near room temperature in the strained ferroelectric PbTiO₃ nanotubes, which is several times in magnitude larger than that of PbTiO₃ thin films. Such giant adiabatic temperature change is attributed to the extrinsic contribution of unusual domain transition, which involves a dedicated interplay among the electric field, strain, temperature and polarization. Careful selection of external strain allows one to harness the extrinsic contribution to obtain large adiabatic temperature change in ferroelectric nanotubes near room temperature. Our finding provides a novel insight into the electrocaloric response of ferroelectric nanostructures and leads to a new strategy to tailor and improve the electrocaloric properties of ferroelectric materials through domain engineering. PMID:25578434

  5. Giant electrocaloric effect in ferroelectric nanotubes near room temperature

    PubMed Central

    Liu, Man; Wang, Jie

    2015-01-01

    Ferroelectric perovskite oxides possess large electrocaloric effect, but only at high temperature, which limits their potential as next generation solid state cooling devices. Here, we demonstrate from phase field simulations that a giant adiabatic temperature change exhibits near room temperature in the strained ferroelectric PbTiO3 nanotubes, which is several times in magnitude larger than that of PbTiO3 thin films. Such giant adiabatic temperature change is attributed to the extrinsic contribution of unusual domain transition, which involves a dedicated interplay among the electric field, strain, temperature and polarization. Careful selection of external strain allows one to harness the extrinsic contribution to obtain large adiabatic temperature change in ferroelectric nanotubes near room temperature. Our finding provides a novel insight into the electrocaloric response of ferroelectric nanostructures and leads to a new strategy to tailor and improve the electrocaloric properties of ferroelectric materials through domain engineering. PMID:25578434

  6. A Na(+) Superionic Conductor for Room-Temperature Sodium Batteries.

    PubMed

    Song, Shufeng; Duong, Hai M; Korsunsky, Alexander M; Hu, Ning; Lu, Li

    2016-01-01

    Rechargeable lithium ion batteries have ruled the consumer electronics market for the past 20 years and have great significance in the growing number of electric vehicles and stationary energy storage applications. However, in addition to concerns about electrochemical performance, the limited availability of lithium is gradually becoming an important issue for further continued use and development of lithium ion batteries. Therefore, a significant shift in attention has been taking place towards new types of rechargeable batteries such as sodium-based systems that have low cost. Another important aspect of sodium battery is its potential compatibility with the all-solid-state design where solid electrolyte is used to replace liquid one, leading to simple battery design, long life span, and excellent safety. The key to the success of all-solid-state battery design is the challenge of finding solid electrolytes possessing acceptable high ionic conductivities at room temperature. Herein, we report a novel sodium superionic conductor with NASICON structure, Na3.1Zr1.95Mg0.05Si2PO12 that shows high room-temperature ionic conductivity of 3.5 × 10(-3) S cm(-1). We also report successful fabrication of a room-temperature solid-state Na-S cell using this conductor. PMID:27572915

  7. A Na+ Superionic Conductor for Room-Temperature Sodium Batteries

    PubMed Central

    Song, Shufeng; Duong, Hai M.; Korsunsky, Alexander M.; Hu, Ning; Lu, Li

    2016-01-01

    Rechargeable lithium ion batteries have ruled the consumer electronics market for the past 20 years and have great significance in the growing number of electric vehicles and stationary energy storage applications. However, in addition to concerns about electrochemical performance, the limited availability of lithium is gradually becoming an important issue for further continued use and development of lithium ion batteries. Therefore, a significant shift in attention has been taking place towards new types of rechargeable batteries such as sodium-based systems that have low cost. Another important aspect of sodium battery is its potential compatibility with the all-solid-state design where solid electrolyte is used to replace liquid one, leading to simple battery design, long life span, and excellent safety. The key to the success of all-solid-state battery design is the challenge of finding solid electrolytes possessing acceptable high ionic conductivities at room temperature. Herein, we report a novel sodium superionic conductor with NASICON structure, Na3.1Zr1.95Mg0.05Si2PO12 that shows high room-temperature ionic conductivity of 3.5 × 10−3 S cm−1. We also report successful fabrication of a room-temperature solid-state Na-S cell using this conductor. PMID:27572915

  8. Solid-state {sup 19}F and {sup 13}C NMR of room temperature fluorinated graphite and samples thermally treated under fluorine: Low-field and high-resolution studies

    SciTech Connect

    Giraudet, J.; Dubois, M.; Guerin, K.; Pinheiro, J.P.; Hamwi, A.; Stone, W.E.E.; Pirotte, P.; Masin, F. . E-mail: fmasin@ulb.ac.be

    2005-04-15

    Room temperature graphite fluorides consisting of raw material and samples post-treated in pure fluorine atmosphere in the temperature range 100-500 deg. C have been studied by solid-state NMR. Several NMR approaches have been used, both high and low-field {sup 19}F, {sup 19}F MAS and {sup 13}C MAS with {sup 19}F to {sup 13}C cross polarization. The modifications, in the graphitic lattice, of the catalytic iodine fluorides products have been examined. A transformation of the C-F bond character from semi-ionic to covalent has been found to occur at a post-treatment temperature close to 400 deg. C. It is shown that covalency increases with temperature.

  9. Electric control of magnetism at room temperature

    PubMed Central

    Wang, Liaoyu; Wang, Dunhui; Cao, Qingqi; Zheng, Yuanxia; Xuan, Haicheng; Gao, Jinlong; Du, Youwei

    2012-01-01

    In the single-phase multiferroics, the coupling between electric polarization (P) and magnetization (M) would enable the magnetoelectric (ME) effect, namely M induced and modulated by E, and conversely P by H. Especially, the manipulation of magnetization by an electric field at room-temperature is of great importance in technological applications, such as new information storage technology, four-state logic device, magnetoelectric sensors, low-power magnetoelectric device and so on. Furthermore, it can reduce power consumption and realize device miniaturization, which is very useful for the practical applications. In an M-type hexaferrite SrCo2Ti2Fe8O19, large magnetization and electric polarization were observed simultaneously at room-temperature. Moreover, large effect of electric field-controlled magnetization was observed even without magnetic bias field. These results illuminate a promising potential to apply in magnetoelectric devices at room temperature and imply plentiful physics behind them. PMID:22355737

  10. Dynamics of Glass Relaxation at Room Temperature

    NASA Astrophysics Data System (ADS)

    Welch, Roger C.; Smith, John R.; Potuzak, Marcel; Guo, Xiaoju; Bowden, Bradley F.; Kiczenski, T. J.; Allan, Douglas C.; King, Ellyn A.; Ellison, Adam J.; Mauro, John C.

    2013-06-01

    The problem of glass relaxation under ambient conditions has intrigued scientists and the general public for centuries, most notably in the legend of flowing cathedral glass windows. Here we report quantitative measurement of glass relaxation at room temperature. We find that Corning® Gorilla® Glass shows measurable and reproducible relaxation at room temperature. Remarkably, this relaxation follows a stretched exponential decay rather than simple exponential relaxation, and the value of the stretching exponent (β=3/7) follows a theoretical prediction made by Phillips for homogeneous glasses.

  11. Room Temperature Multiferroicity of Charge Transfer Crystals.

    PubMed

    Qin, Wei; Chen, Xiaomin; Li, Huashan; Gong, Maogang; Yuan, Guoliang; Grossman, Jeffrey C; Wuttig, Manfred; Ren, Shenqiang

    2015-09-22

    Room temperature multiferroics has been a frontier research field by manipulating spin-driven ferroelectricity or charge-order-driven magnetism. Charge-transfer crystals based on electron donor and acceptor assembly, exhibiting simultaneous spin ordering, are drawing significant interests for the development of all-organic magnetoelectric multiferroics. Here, we report that a remarkable anisotropic magnetization and room temperature multiferroicity can be achieved through assembly of thiophene donor and fullerene acceptor. The crystal motif directs the dimensional and compositional control of charge-transfer networks that could switch magnetization under external stimuli, thereby opening up an attractive class of all-organic nanoferronics. PMID:26257033

  12. Widely tunable room temperature semiconductor terahertz source

    SciTech Connect

    Lu, Q. Y.; Slivken, S.; Bandyopadhyay, N.; Bai, Y.; Razeghi, M.

    2014-11-17

    We present a widely tunable, monolithic terahertz source based on intracavity difference frequency generation within a mid-infrared quantum cascade laser at room temperature. A three-section ridge waveguide laser design with two sampled grating sections and a distributed-Bragg section is used to achieve the terahertz (THz) frequency tuning. Room temperature single mode THz emission with a wide tunable frequency range of 2.6–4.2 THz (∼47% of the central frequency) and THz power up to 0.1 mW is demonstrated, making such device an ideal candidate for THz spectroscopy and sensing.

  13. Room-temperature antiferromagnetic memory resistor.

    PubMed

    Marti, X; Fina, I; Frontera, C; Liu, Jian; Wadley, P; He, Q; Paull, R J; Clarkson, J D; Kudrnovský, J; Turek, I; Kuneš, J; Yi, D; Chu, J-H; Nelson, C T; You, L; Arenholz, E; Salahuddin, S; Fontcuberta, J; Jungwirth, T; Ramesh, R

    2014-04-01

    The bistability of ordered spin states in ferromagnets provides the basis for magnetic memory functionality. The latest generation of magnetic random access memories rely on an efficient approach in which magnetic fields are replaced by electrical means for writing and reading the information in ferromagnets. This concept may eventually reduce the sensitivity of ferromagnets to magnetic field perturbations to being a weakness for data retention and the ferromagnetic stray fields to an obstacle for high-density memory integration. Here we report a room-temperature bistable antiferromagnetic (AFM) memory that produces negligible stray fields and is insensitive to strong magnetic fields. We use a resistor made of a FeRh AFM, which orders ferromagnetically roughly 100 K above room temperature, and therefore allows us to set different collective directions for the Fe moments by applied magnetic field. On cooling to room temperature, AFM order sets in with the direction of the AFM moments predetermined by the field and moment direction in the high-temperature ferromagnetic state. For electrical reading, we use an AFM analogue of the anisotropic magnetoresistance. Our microscopic theory modelling confirms that this archetypical spintronic effect, discovered more than 150 years ago in ferromagnets, is also present in AFMs. Our work demonstrates the feasibility of fabricating room-temperature spintronic memories with AFMs, which in turn expands the base of available magnetic materials for devices with properties that cannot be achieved with ferromagnets. PMID:24464243

  14. Room-temperature antiferromagnetic memory resistor

    NASA Astrophysics Data System (ADS)

    Marti, X.; Fina, I.; Frontera, C.; Liu, Jian; Wadley, P.; He, Q.; Paull, R. J.; Clarkson, J. D.; Kudrnovský, J.; Turek, I.; Kuneš, J.; Yi, D.; Chu, J.-H.; Nelson, C. T.; You, L.; Arenholz, E.; Salahuddin, S.; Fontcuberta, J.; Jungwirth, T.; Ramesh, R.

    2014-04-01

    The bistability of ordered spin states in ferromagnets provides the basis for magnetic memory functionality. The latest generation of magnetic random access memories rely on an efficient approach in which magnetic fields are replaced by electrical means for writing and reading the information in ferromagnets. This concept may eventually reduce the sensitivity of ferromagnets to magnetic field perturbations to being a weakness for data retention and the ferromagnetic stray fields to an obstacle for high-density memory integration. Here we report a room-temperature bistable antiferromagnetic (AFM) memory that produces negligible stray fields and is insensitive to strong magnetic fields. We use a resistor made of a FeRh AFM, which orders ferromagnetically roughly 100 K above room temperature, and therefore allows us to set different collective directions for the Fe moments by applied magnetic field. On cooling to room temperature, AFM order sets in with the direction of the AFM moments predetermined by the field and moment direction in the high-temperature ferromagnetic state. For electrical reading, we use an AFM analogue of the anisotropic magnetoresistance. Our microscopic theory modelling confirms that this archetypical spintronic effect, discovered more than 150 years ago in ferromagnets, is also present in AFMs. Our work demonstrates the feasibility of fabricating room-temperature spintronic memories with AFMs, which in turn expands the base of available magnetic materials for devices with properties that cannot be achieved with ferromagnets.

  15. Room Temperature and Elevated Temperature Composite Sandwich Joint Testing

    NASA Technical Reports Server (NTRS)

    Walker, Sandra P.

    1998-01-01

    Testing of composite sandwich joint elements has been completed to verify the strength capacity of joints designed to carry specified running loads representative of a high speed civil transport wing. Static tension testing at both room and an elevated temperature of 350 F and fatigue testing at room temperature were conducted to determine strength capacity, fatigue life, and failure modes. Static tension test results yielded failure loads above the design loads for the room temperature tests, confirming the ability of the joint concepts tested to carry their design loads. However, strength reductions as large as 30% were observed at the elevated test temperature, where all failure loads were below the room temperature design loads for the specific joint designs tested. Fatigue testing resulted in lower than predicted fatigue lives.

  16. Preparation and Use of a Room-Temperature Catalytic Converter

    NASA Astrophysics Data System (ADS)

    Wong, Gareth; Mark, Bernard; Chen, Xijia; Furch, Toran; Singmaster, K. A.; Wagenknecht, Paul S.

    2001-12-01

    A solid-state catalyst that effectively converts a CO/air mixture to CO2 at room temperature is readily prepared. The catalyst, which is composed of metallic gold on iron(III) oxide, is loaded into a simple flow cell to test its catalytic activity. Mixtures of CO and air are run through the catalyst and subsequently analyzed by gas-phase infrared spectroscopy to determine the effectiveness of the catalyst.

  17. Imprinting bulk amorphous alloy at room temperature

    SciTech Connect

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.

  18. Imprinting bulk amorphous alloy at room temperature

    PubMed Central

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-01-01

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. Our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment. PMID:26563908

  19. Imprinting bulk amorphous alloy at room temperature.

    PubMed

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T; Lograsso, Thomas A; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-01-01

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. Our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment. PMID:26563908

  20. Room-temperature semiconductor heterostructure refrigeration

    NASA Astrophysics Data System (ADS)

    Chao, K. A.; Larsson, Magnus; Mal'shukov, A. G.

    2005-07-01

    With the proper design of semiconductor tunneling barrier structures, we can inject low-energy electrons via resonant tunneling, and take out high-energy electrons via a thermionic process. This is the operation principle of our semiconductor heterostructure refrigerator (SHR) without the need of applying a temperature gradient across the device. Even for the bad thermoelectric material AlGaAs, our calculation shows that at room temperature, the SHR can easily lower the temperature by 5-7K. Such devices can be fabricated with the present semiconductor technology. Besides its use as a kitchen refrigerator, the SHR can efficiently cool microelectronic devices.

  1. Individual room temperature control: A peaceful solution to thermostat wars

    SciTech Connect

    Pieper, C.A. )

    1994-01-01

    This article addresses the problem of maintaining thermal comfort in individual rooms using an individual room temperature control concept to provide greater occupant comfort and potentially reduce energy consumption. The topics of the article include occupant temperature control methods, multi-room zone control, HVAC system operation, computer simulation, and the results of using individual room temperature control.

  2. Colossal magnetocapacitance effect at room temperature

    NASA Astrophysics Data System (ADS)

    Bishchaniuk, T. M.; Grygorchak, I. I.

    2014-05-01

    First nano-hybridized clathrate/cavitant structure of hierarchical architecture was synthesized. The results of investigations of the properties of initial nanoporous silica matrices MCM-41, with encapsulated in its pores of β-cyclodextrin in cavitand and cavitat (with FeSO4) states and change at room temperature in a constant magnetic field intensity of 2.75 kOe, have been presented. Phenomenon of enormous magnetocapacitance and giant negative variable-current magnetoresistance has been discovered.

  3. Room-temperature paramagnetoelectric effect in magnetoelectric multiferroics Pb(Fe1/2Nb1/2)O3 and its solid solution with PbTiO3

    NASA Astrophysics Data System (ADS)

    Laguta, V. V.; Morozovska, A. N.; Eliseev, E. A.; Raevski, I. P.; Raevskaya, S. I.; Sitalo, E. I.; Prosandeev, S. A.; Bellaiche, L.

    2016-06-01

    We have observed the magnetoelectric response at room temperature and above in high-resistive ceramics made of multiferroic Pb(Fe1/2Nb1/2)O3 (PFN) and PFN-based solid solution 0.91PFN-0.09PbTiO3 (PFN-PT). The value of the paramagnetoelectric (PME) coefficient shows a pronounced maximum near the ferroelectric-to-paraelectric phase transition temperature, T_C, and then decreases sharply to zero for T>T_C. The maximal PME coefficient in PFN is about 4x10(-18) s/A. The theoretical description of the PME effect, within the framework of a Landau theory of phase transitions allowing for realistic temperature dependences of spontaneous polarization, dielectric and magnetic susceptibilities, qualitatively reproduces well the temperature dependence of the PME coefficient. In particular, the Landau theory predicts the significant increase of the PME effect at low temperatures and near the temperature of the paraelectric-to-ferroelectric phase transition, since the PME coefficient is equal to the product of the spontaneous polarization, dielectric permittivity, square of magnetic susceptibility and the coefficient quantifying the strength of the biquadratic magnetoelectric coupling

  4. Magnetic heat pumping near room temperature

    NASA Technical Reports Server (NTRS)

    Brown, G. V.

    1976-01-01

    It is shown that magnetic heat pumping can be made practical at room temperature by using a ferromagnetic material with a Curie point at or near operating temperature and an appropriate regenerative thermodynamic cycle. Measurements are performed which show that gadolinium is a resonable working material and it is found that the application of a 7-T magnetic field to gadolinium at the Curie point (293 K) causes a heat release of 4 kJ/kg under isothermal conditions or a temperature rise of 14 K under adiabatic conditions. A regeneration technique can be used to lift the load of the lattice and electronic heat capacities off the magnetic system in order to span a reasonable temperature difference and to pump as much entropy per cycle as possible

  5. A Highly Reversible Room-Temperature Sodium Metal Anode

    PubMed Central

    2015-01-01

    Owing to its low cost and high natural abundance, sodium metal is among the most promising anode materials for energy storage technologies beyond lithium ion batteries. However, room-temperature sodium metal anodes suffer from poor reversibility during long-term plating and stripping, mainly due to formation of nonuniform solid electrolyte interphase as well as dendritic growth of sodium metal. Herein we report for the first time that a simple liquid electrolyte, sodium hexafluorophosphate in glymes (mono-, di-, and tetraglyme), can enable highly reversible and nondendritic plating–stripping of sodium metal anodes at room temperature. High average Coulombic efficiencies of 99.9% were achieved over 300 plating–stripping cycles at 0.5 mA cm–2. The long-term reversibility was found to arise from the formation of a uniform, inorganic solid electrolyte interphase made of sodium oxide and sodium fluoride, which is highly impermeable to electrolyte solvent and conducive to nondendritic growth. As a proof of concept, we also demonstrate a room-temperature sodium–sulfur battery using this class of electrolytes, paving the way for the development of next-generation, sodium-based energy storage technologies. PMID:27163006

  6. A Highly Reversible Room-Temperature Sodium Metal Anode.

    PubMed

    Seh, Zhi Wei; Sun, Jie; Sun, Yongming; Cui, Yi

    2015-11-25

    Owing to its low cost and high natural abundance, sodium metal is among the most promising anode materials for energy storage technologies beyond lithium ion batteries. However, room-temperature sodium metal anodes suffer from poor reversibility during long-term plating and stripping, mainly due to formation of nonuniform solid electrolyte interphase as well as dendritic growth of sodium metal. Herein we report for the first time that a simple liquid electrolyte, sodium hexafluorophosphate in glymes (mono-, di-, and tetraglyme), can enable highly reversible and nondendritic plating-stripping of sodium metal anodes at room temperature. High average Coulombic efficiencies of 99.9% were achieved over 300 plating-stripping cycles at 0.5 mA cm(-2). The long-term reversibility was found to arise from the formation of a uniform, inorganic solid electrolyte interphase made of sodium oxide and sodium fluoride, which is highly impermeable to electrolyte solvent and conducive to nondendritic growth. As a proof of concept, we also demonstrate a room-temperature sodium-sulfur battery using this class of electrolytes, paving the way for the development of next-generation, sodium-based energy storage technologies. PMID:27163006

  7. Irradiation dose determination below room temperature

    NASA Astrophysics Data System (ADS)

    Ramos-Bernal, S.; Cruz, E.; Negrón-Mendoza, A.; Bustos, E.

    2002-03-01

    The measurements presented were undertaken to provide quantitative information on the low temperature irradiation of thermoluminiscence phosphors. The crystals used were (a) LiF co-doped with Mg, Cu and P, and (b) CaSO 4 doped with Dy. The absorbed dose values in the interval studied showed a linear behavior at low doses and low temperature. The aim of this work is to test if these crystals can be used to measure the dose absorbed by solids at low temperature.

  8. Imprinting bulk amorphous alloy at room temperature

    DOE PAGESBeta

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the abilitymore » of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.« less

  9. Room temperature electrically injected polariton laser.

    PubMed

    Bhattacharya, Pallab; Frost, Thomas; Deshpande, Saniya; Baten, Md Zunaid; Hazari, Arnab; Das, Ayan

    2014-06-13

    Room temperature electrically pumped inversionless polariton lasing is observed from a bulk GaN-based microcavity diode. The low nonlinear threshold for polariton lasing occurs at 169 A/cm(2) in the light-current characteristics, accompanied by a collapse of the emission linewidth and small blueshift of the emission peak. Measurement of angle-resolved luminescence, polariton condensation and occupation in momentum space, and output spatial coherence and polarization have also been made. A second threshold, due to conventional photon lasing, is observed at an injection of 44 kA/cm(2). PMID:24972222

  10. Absorber Materials at Room and Cryogenic Temperatures

    SciTech Connect

    F. Marhauser, T.S. Elliott, A.T. Wu, E.P. Chojnacki, E. Savrun

    2011-09-01

    We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

  11. A study of room-temperature LixMn1.5Ni0.5O4 solid solutions

    SciTech Connect

    Saravanan, Kuppan; Jarry, Angelique; Kostecki, Robert; Chen, Guoying

    2015-01-26

    Understanding the kinetic implication of solid-solution vs. biphasic reaction pathways is critical for the development of advanced intercalation electrode materials. Yet this has been a long-standing challenge in materials science due to the elusive metastable nature of solid solution phases. The present study reports the synthesis, isolation, and characterization of room-temperature LixMn1.5Ni0.5O4 solid solutions. In situ XRD studies performed on pristine and chemically-delithiated, micron-sized single crystals reveal the thermal behavior of LixMn1.5Ni0.5O4 (0 ≤ x ≤ 1) cathode material consisting of three cubic phases: LiMn1.5Ni0.5O4 (Phase I), Li0.5Mn1.5Ni0.5O4 (Phase II) and Mn1.5Ni0.5O4 (Phase III). A phase diagram capturing the structural changes as functions of both temperature and Li content was established. In conclusion, the work not only demonstrates the possibility of synthesizing alternative electrode materials that are metastable in nature, but also enables in-depth evaluation on the physical, electrochemical and kinetic properties of transient intermediate phases and their role in battery electrode performance.

  12. Room-temperature storage of microalgae in water-in-oil emulsions: influence of solid particle type and concentration in the oil phase.

    PubMed

    Fernández, Lorena; Scher, Herbert; Jeoh, Tina; VanderGheynst, Jean S

    2015-12-01

    Water-in-oil emulsions containing silica nanoparticles (Aerosil R974) have the potential to stabilize microalgae for long-term storage. Studies were completed to determine if smectite clays could be used as an alternative to Aerosil R974. Emulsions were prepared with Aerosil R974, and hectorite and bentonite clays in the continuous phase and Chlorella sorokiniana was added to the aqueous phase to monitor the effects of solid particles on emulsion stability. Biological stability (cell viability) was determined using cell density measurements, and physical stability was measured from water droplet size distributions obtained by light scattering measurements and by examining phase separation over time. Measurements were also made to determine the effects of particles in the oil phase on emulsion viscosity. Particle concentrations greater than 0.25 wt% in the oil phase were required for maintaining physical stability. In emulsions containing 1 wt% solid particles and microalgae, biological stability of cells could be sustained for 340 days, regardless of particle type. At 1 wt% particles in the oil phase, apparent viscosity was 165% greater for samples containing hectorite and bentonite clays compared to samples containing Aerosil R974. The higher viscosity would need to be considered in large-scale production of emulsions for commercial application. PMID:26463181

  13. Phase diagram of the system of (1- x)BiFeO3- x PbFe0.5Nb0.5O3 solid solutions at room temperature

    NASA Astrophysics Data System (ADS)

    Shilkina, L. A.; Pavlenko, A. V.; Reznitchenko, L. A.; Verbenko, I. A.

    2016-03-01

    Experimental samples of solid solutions of the (1- x)BiFeO3- x PbFe0.5Nb0.5O3 (0.00 ≤ x ≤ 1.00, Δ x = 0.025-0.05) system have been prepared according to the conventional ceramic technology. Their structural and dielectric characteristics have been studied. A phase diagram of the system at room temperature has been plotted taking into account the crystallochemical specificity, spatial inhomogeneity, and structural imperfection of the samples. This diagram is characterized by the presence of solid substitutional and interstitial solutions; the formation of concentration ranges with a dominant role of BiFeO3 and PbFe0.5Nb0.5O3; the presence of five single-phase regions, two regions of coexistence of phase states, and three morphotropic regions; and the formation of six regions with a constant experimental unit-cell volume. Correlations between the structural characteristics and dielectric properties of the ceramics under study have been established.

  14. Room temperature neutron diffraction and magnetic studies of multiferroic Pb0.9Bi0.1Fe0.55Nb0.45O3 solid solution

    NASA Astrophysics Data System (ADS)

    Dadami, S. T.; Matteppanavar, S.; Shivaraja, I.; Rayaprol, S.; Deshpande, S. K.; Angadi, B.

    2016-05-01

    The Pb0.9Bi0.1Fe0.55Nb0.45O3 (PBFNO) solid solution was synthesized by single step solid state reaction method and the optimized parameters are 700°C for 2hr (calcination) and 800°C for 3hr (sintering). The formation of desired material was confirmed using X-Ray Diffraction (XRD) and Neutron Diffraction (ND) studies. The structural and magnetic properties of the sintered pellets were investigated at room temperature (RT) through XRD, ND and Magnetic (M-H) studies. The structural analysis was carried out by Rietveld refinement through the Full Prof program. Rietveld refined XRD and ND patterns confirms the monoclinic structure with Cm space group and obtained cell parameters from the ND data are a = 5.651(2) Å, b = 5.658(2) Å, c = 4.005(1) Å and α = 90°, β = 89.98(1)°, γ = 90°. RT M-H curve studies have been carried out. It shows the clear opening of hysteresis (M-H) loop, is evidenced as the existence of weak ferromagnetism at RT. The M-H data shows existence weak ferromagnetism embedded in an antiferromagnetic matrix structure. The dielectric constant with frequency shows the formation of barrier layers at the grain and grain boundary interfaces gives rise to interfacial space charge polarization.

  15. Room temperature luminescence and ferromagnetism of AlN:Fe

    NASA Astrophysics Data System (ADS)

    Li, H.; Cai, G. M.; Wang, W. J.

    2016-06-01

    AlN:Fe polycrystalline powders were synthesized by a modified solid state reaction (MSSR) method. Powder X-ray diffraction and transmission electron microscopy results reveal the single phase nature of the doped samples. In the doped AlN samples, Fe is in Fe2+ state. Room temperature ferromagnetic behavior is observed in AlN:Fe samples. Two photoluminescence peaks located at about 592 nm (2.09 eV) and 598 nm (2.07 eV) are observed in AlN:Fe samples. Our results suggest that AlN:Fe is a potential material for applications in spintronics and high power laser devices.

  16. Determination of trace selenium by solid substrate-room temperature phosphorescence enhancing method based on potassium chlorate oxidizing phenyl hydrazine-1,2-dihydroxynaphthalene-3,6-disulfonic acid system

    NASA Astrophysics Data System (ADS)

    Liu, Jia-Ming; Cui, Xiao-Jie; Li, Lai-Ming; Fu, Geng-Min; Lin, Shao-Xian; Yang, Min-Lan; Xu, Mei-Ying; Wu, Zhi-Qun

    2007-04-01

    A new method for the determination of trace selenium based on solid substrate-room temperature phosphorimetry (SS-RTP) has been established. This method was based on the fact that in HCl-KCl buffer solution, potassium chlorate could oxidize phenyl hydrazine to form chloridize diazo-ion after being heated at 100 °C for 20 min, and then the diazo-ion reacted with 1,2-dihydroxynaphthalene-3,6-disulfonic acid to form red azo-compound which could emit strong room temperature phosphorescence (RTP) signal on filter paper. Selenium could catalyze potassium chlorate oxidizing the reaction between phenyl hydrazine and 1,2-dihydroxynaphthalene-3,6-disulfonic acid, which caused the sharp enhancement of SS-RTP. Under the optimum condition, the relationship between the phosphorescence emission intensity (Δ Ip) and the content of selenium obeyed Beer's law when the concentration of selenium is within the range of 1.60-320 fg spot -1 (or 0.0040-0.80 ng ml -1 with a sample volume of 0.4 μl). The regression equation of working curve can be expressed as Δ Ip = 13.12 + 0.4839 CSe(IV) (fg spot -1) ( n = 6), with correlation coefficient r = 0.9991 and a detection limit of 0.28 fg spot -1 (corresponding to a concentration range of 7.0 × 10 -13 g ml -1 Se(IV), n = 11). After 11-fold measurement, R.S.D. were 2.8 and 3.5% for the samples containing 0.0040 and 0.80 ng ml -1 of Se(IV), respectively. This accurate and sensitive method with good repeatability has been successfully applied to the determination of trace selenium in Chinese wolfberry and egg yolk with satisfactory results. The mechanism of the enhancement of phosphorescence was also discussed.

  17. Atomically resolved force microscopy at room temperature

    SciTech Connect

    Morita, Seizo

    2014-04-24

    Atomic force microscopy (AFM) can now not only image individual atoms but also construct atom letters using atom manipulation method even at room temperature (RT). Therefore, the AFM is the second generation atomic tool following the scanning tunneling microscopy (STM). However the AFM can image even insulating atoms, and also directly measure/map the atomic force and potential at the atomic scale. Noting these advantages, we have been developing a bottom-up nanostructuring system at RT based on the AFM. It can identify chemical species of individual atoms and then manipulate selected atom species to the predesigned site one-by-one to assemble complex nanostructures consisted of multi atom species at RT. Here we introduce our results toward atom-by-atom assembly of composite nanostructures based on the AFM at RT including the latest result on atom gating of nano-space for atom-by-atom creation of atom clusters at RT for semiconductor surfaces.

  18. Structure of room temperature ionic liquids.

    PubMed

    Yethiraj, Arun

    2016-10-19

    The structure of room temperature ionic liquids is studied using molecular dynamics simulations and integral equation theory. Three ionic liquids 1-alkyl-3-methylimidazolium hexfluorophosphate, [C n MIM] [PF6], for n  =  1, 4, and 8, are studied using a united atom model of the ions. The primary interest is a study of the pair correlation functions and a test of the reference interaction site model theory. There is liquid-like ordering in the liquid that arises from electrostatic attractions and steric packing considerations. The theory is not in quantitative agreement with the simulation results and underestimates the degree of liquid-like order. A pre-peak in the static structure factor is seen in both simulations and theory, suggesting that this is a geometric effect arising from a packing of the alkyl chains. PMID:27546807

  19. Electrorecovery of actinides at room temperature

    SciTech Connect

    Stoll, Michael E; Oldham, Warren J; Costa, David A

    2008-01-01

    There are a large number of purification and processing operations involving actinide species that rely on high-temperature molten salts as the solvent medium. One such application is the electrorefining of impure actinide metals to provide high purity material for subsequent applications. There are some drawbacks to the electrodeposition of actinides in molten salts including relatively low yields, lack of accurate potential control, maintaining efficiency in a highly corrosive environment, and failed runs. With these issues in mind we have been investigating the electrodeposition of actinide metals, mainly uranium, from room temperature ionic liquids (RTILs) and relatively high-boiling organic solvents. The RTILs we have focused on are comprised of 1,3-dialkylimidazolium or quaternary ammonium cations and mainly the {sup -}N(SO{sub 2}CF{sub 3}){sub 2} anion [bis(trif1uoromethylsulfonyl)imide {equivalent_to} {sup -}NTf{sub 2}]. These materials represent a class of solvents that possess great potential for use in applications employing electrochemical procedures. In order to ascertain the feasibility of using RTILs for bulk electrodeposition of actinide metals our research team has been exploring the electron transfer behavior of simple coordination complexes of uranium dissolved in the RTIL solutions. More recently we have begun some fundamental electrochemical studies on the behavior of uranium and plutonium complexes in the organic solvents N-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO). Our most recent results concerning electrodeposition will be presented in this account. The electrochemical behavior of U(IV) and U(III) species in RTILs and the relatively low vapor pressure solvents NMP and DMSO is described. These studies have been ongoing in our laboratory to uncover conditions that will lead to the successful bulk electrodeposition of actinide metals at a working electrode surface at room temperature or slightly elevated temperatures. The RTILs we

  20. A Two-Dimensional Inorganic-Organic Hybrid Solid of Manganese(II) Hydrogenophosphate Showing High Proton Conductivity at Room Temperature.

    PubMed

    Zhao, Hai-Rong; Xue, Chen; Li, Cui-Ping; Zhang, Kai-Ming; Luo, Hong-Bin; Liu, Shao-Xian; Ren, Xiao-Ming

    2016-09-01

    The inorganic-organic hybrid metal hydrogenophosphate with a formula of (C2H10N2)[Mn2(HPO4)3](H2O) (1) shows layered crystal structure. The inorganic anion layer is built from Mn3O13 cluster units, and the interlayer spaces are filled by the charge-compensated ethylenediammonium dications together with the lattice water molecules. The thermogravimetry, variable-temperature powder X-ray diffraction, and the proton conductance under anhydrous and moisture environments were investigated for 1, disclosing that 1 shows high thermal stability and high proton transport nature, and the proton conductivity reaches to 1.64 × 10(-3) S·cm(-1) under 99%RH even at 293 K. The high proton conductivity is related to the formation of denser H-bond networks in the lattice. PMID:27509084

  1. Thiazolylimines as novel ligand-systems for spin-crossover centred near room temperature.

    PubMed

    Struch, N; Wagner, N; Schnakenburg, G; Weisbarth, R; Klos, S; Beck, J; Lützen, A

    2016-09-28

    A new thiazolylimine ligand system for iron(ii) complexes which stabilises spin-crossover in solution and solid states with T1/2 temperatures around room temperature has been developed. This effect is studied in solution and solid states. Furthermore crystal packing effects are investigated offering a variety of T1/2 and even hysteresis centred at -3 °C in the solid state. PMID:27534997

  2. Single-molecule spectroscopy and dynamics at room temperature

    SciTech Connect

    Xie, X.S.

    1996-12-01

    The spirit of studying single-molecule behaviors dates back to the turn of the century. In addition to Einstein`s well-known work on Brownian motion, there has been a tradition for studying single {open_quotes}macromolecules{close_quotes} or a small number of molecules either by light scattering or by fluorescence using an optical microscope. Modern computers have allowed detailed studies of single-molecule behaviors in condensed media through molecular dynamics simulations. Optical spectroscopy offers a wealth of information on the structure, interaction, and dynamics of molecular species. With the motivation of removing {open_quotes}inhomogeneous broadening{close_quotes}, spectroscopic techniques have evolved from spectral hole burning, fluorescence line narrowing, and photo-echo to the recent pioneering work on single-molecule spectroscopy in solids at cryogenic temperatures. High-resolution spectroscopic work on single molecules relies on zero phonon lines which appear at cryogenic temperatures, and have narrow line widths and large absorption cross sections. Recent advances in near-field and confocal fluorescence have allowed not only fluorescence imaging of single molecules with high spatial resolutions but also single-molecule spectroscopy at room temperature. In this Account, the author provides a physical chemist`s perspective on experimental and theoretical developments on room-temperature single-molecule spectroscopy and dynamics, with the emphasis on the information obtainable from single-molecule experiments. 61 refs., 9 figs.

  3. HPXe ionization chambers for γ spectrometry at room temperature

    NASA Astrophysics Data System (ADS)

    Ottini-Hustache, S.; Monsanglant-Louvet, C.; Haan, S.; Dmitrenko, V.; Grachev, V.; Ulin, S.

    2004-01-01

    High pressure xenon (HPXe) ionization chambers exhibit many characteristics which make them particularly suitable for industrial γ spectrometry at room or higher temperature. The use of a gas as detection medium allows one to reach very large effective volumes and makes these chambers relatively insensitive to radiation damage. Further, the high atomic number of xenon ( Z=54) enhances the total absorption of incident photons and provides, combined to high pressure, a good enough detection efficiency with respect to solid state detectors. Furthermore, such ionization chambers with Frisch grid appear to be very stable over wide periods (e.g. a research prototype has been used aboard MIR orbital station for several years) and temperature range (up to 180°), without maintenance. The characteristics of different prototypes are presented. Their detection efficiency and energy resolution are studied as a function of incident γ ray energy. New developments in electronics and signal processing are also investigated to improve their performances.

  4. Room temperature molecular up conversion in solution.

    PubMed

    Nonat, Aline; Chan, Chi Fai; Liu, Tao; Platas-Iglesias, Carlos; Liu, Zhenyu; Wong, Wing-Tak; Wong, Wai-Kwok; Wong, Ka-Leung; Charbonnière, Loïc J

    2016-01-01

    Up conversion is an Anti-Stokes luminescent process by which photons of low energy are piled up to generate light at a higher energy. Here we show that the addition of fluoride anions to a D2O solution of a macrocyclic erbium complex leads to the formation of a supramolecular [(ErL)2F](+) assembly in which fluoride is sandwiched between two complexes, held together by the synergistic interactions of the Er-F-Er bridging bond, four intercomplex hydrogen bonds and two aromatic stacking interactions. Room temperature excitation into the Er absorption bands at 980 nm of a solution of the complex in D2O results in the observation of up converted emission at 525, 550 and 650 nm attributed to Er centred transitions via a two-step excitation. The up conversion signal is dramatically increased upon formation of the [(ErL)2F](+) dimer in the presence of 0.5 equivalents of fluoride anions. PMID:27302144

  5. Room temperature molecular up conversion in solution

    PubMed Central

    Nonat, Aline; Chan, Chi Fai; Liu, Tao; Platas-Iglesias, Carlos; Liu, Zhenyu; Wong, Wing-Tak; Wong, Wai-Kwok; Wong, Ka-Leung; Charbonnière, Loïc J.

    2016-01-01

    Up conversion is an Anti-Stokes luminescent process by which photons of low energy are piled up to generate light at a higher energy. Here we show that the addition of fluoride anions to a D2O solution of a macrocyclic erbium complex leads to the formation of a supramolecular [(ErL)2F]+ assembly in which fluoride is sandwiched between two complexes, held together by the synergistic interactions of the Er-F-Er bridging bond, four intercomplex hydrogen bonds and two aromatic stacking interactions. Room temperature excitation into the Er absorption bands at 980 nm of a solution of the complex in D2O results in the observation of up converted emission at 525, 550 and 650 nm attributed to Er centred transitions via a two-step excitation. The up conversion signal is dramatically increased upon formation of the [(ErL)2F]+ dimer in the presence of 0.5 equivalents of fluoride anions. PMID:27302144

  6. Room-temperature single-electron junction.

    PubMed Central

    Facci, P; Erokhin, V; Carrara, S; Nicolini, C

    1996-01-01

    The design, realization, and test performances of an electronic junction based on single-electron phenomena that works in the air at room temperature are hereby reported. The element consists of an electrochemically etched sharp tungsten stylus over whose tip a nanometer-size crystal was synthesized. Langmuir-Blodgett films of cadmium arachidate were transferred onto the stylus and exposed to a H2S atmosphere to yield CdS nanocrystals (30-50 angstrom in diameter) imbedded into an organic matrix. The stylus, biased with respect to a flat electrode, was brought to the tunnel distance from the film and a constant gap value was maintained by a piezo-electric actuator driven by a feedback circuit fed by the tunneling current. With this set-up, it is possible to measure the behavior of the current flowing through the quantum dot when a bias voltage is applied. Voltage-current characteristics measured in the system displayed single-electron trends such as a Coulomb blockade and Coulomb staircase and revealed capacitance values as small as 10(-19) F. PMID:11607710

  7. Room-Temperature Multiferroic Hexagonal LuFeO3

    SciTech Connect

    Cheng, Xuemei; Balke, Nina; Chi, Miaofang; Gai, Zheng; Keavney, David; Lee, Ho Nyung; Shen, Jian; Snijders, Paul C; Wang, Wenbin; Ward, Thomas Z; Xu, Xiaoshan; Yi, Jieyu; Zhu, Leyi; Christen, Hans M; Zhao, Jun

    2013-01-01

    We observed the coexistence of ferroelectricity and weak ferromagnetism at room temperature in the hexagonal phase of LuFeO3 stabilized by epitaxial thin film growth. While the ferroelectricity in hexagonal LuFeO3 can be understood as arising from its polar structure, the observation of weak ferromagnetism at room temperature is remarkable considering the frustrated triangular spin structure. An explanation of the room temperature weak ferromagnetism is proposed in terms of a subtle lattice distortion revealed by the structural characterization. The combination of ferroelectricity and weak ferromagnetism in epitaxial films at room temperature offers great potential for the application of this novel multiferroic material in next generation devices.

  8. Determination of trace alkaline phosphatase by affinity adsorption solid substrate room temperature phosphorimetry based on wheat germ agglutinin labeled with 8-quinolineboronic acid phosphorescent molecular switch and prediction of diseases

    NASA Astrophysics Data System (ADS)

    Liu, Jia-Ming; Gao, Hui; Li, Fei-Ming; Shi, Xiu-Mei; Lin, Chang-Qing; Lin, Li-Ping; Wang, Xin-Xing; Li, Zhi-Ming

    2010-09-01

    The 8-quinolineboronic acid phosphorescent molecular switch (abbreviated as PMS-8-QBA. Thereinto, 8-QBA is 8-quinolineboronic acid, and PMS is phosphorescent molecular switch) was found for the first time. PMS-8-QBA, which was in the "off" state, could only emit weak room temperature phosphorescence (RTP) on the acetyl cellulose membrane (ACM). However, PMS-8-QBA turned "on" automatically for its changed structure, causing that the RTP of 8-QBA in the system increased, after PMS-8-QBA-WGA (WGA is wheat germ agglutinin) was formed by reaction between -OH of PMS-8-QBA and -COOH of WGA. More interesting is that the -NH 2 of PMS-8-QBA-WGA could react with the -COOH of alkaline phosphatase (AP) to form the affinity adsorption (AA) product WGA-AP-WGA-8-QBA-PMS (containing -NH-CO- bond), which caused RTP of the system to greatly increase. Thus, affinity adsorption solid substrate room temperature phosphorimetry using PMS-8-QBA as labelling reagent (PMS-8-QBA-AA-SSRTP) for the determination of trace AP was established. The method had many advantages, such as high sensitivity (the detection limit (LD) was 2.5 zg spot -1. For sample volume of 0.40 μl spot -1, corresponding concentration was 6.2 × 10 -18 g ml -1), good selectivity (the allowed concentration of coexisting material was higher, when the relative error was ±5%), high accuracy (applied to detection of AP content in serum samples, the result was coincided with those obtained by enzyme-linked immunoassay), which was suitable for the detection of trace AP content in serum samples and the forecast of human diseases. Meanwhile, the mechanism of PMS-8-QBA-AASSRTP was discussed. The new field of analytical application and clinic diagnosis technique of molecule switch are exploited, based on the phosphorescence characteristic of PMS-8-QBA, the AA reaction between WGA and AP, as well as the relation between AP content and human diseases. The research results promote the development and interpenetrate among molecule

  9. Water in Room Temperature Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Fayer, Michael

    2014-03-01

    Room temperature ionic liquids (or RTILs, salts with a melting point below 25 °C) have become a subject of intense study over the last several decades. Currently, RTIL application research includes synthesis, batteries, solar cells, crystallization, drug delivery, and optics. RTILs are often composed of an inorganic anion paired with an asymmetric organic cation which contains one or more pendant alkyl chains. The asymmetry of the cation frustrates crystallization, causing the salt's melting point to drop significantly. In general, RTILs are very hygroscopic, and therefore, it is of interest to examine the influence of water on RTIL structure and dynamics. In addition, in contrast to normal aqueous salt solutions, which crystallize at low water concentration, in an RTIL it is possible to examine isolated water molecules interacting with ions but not with other water molecules. Here, optical heterodyne-detected optical Kerr effect (OHD-OKE) measurements of orientational relaxation on a series of 1-alkyl-3-methylimidazolium tetrafluoroborate RTILs as a function of chain length and water concentration are presented. The addition of water to the longer alkyl chain RTILs causes the emergence of a long time bi-exponential orientational anisotropy decay. Such decays have not been seen previously in OHD-OKE experiments on any type of liquid and are analyzed here using a wobbling-in-a-cone model. The orientational relaxation is not hydrodynamic, with the slowest relaxation component becoming slower as the viscosity decreases for the longest chain, highest water content samples. The dynamics of isolated D2O molecules in 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF6) were examined using two dimensional infrared (2D IR) vibrational echo spectroscopy. Spectral diffusion and incoherent and coherent transfer of excitation between the symmetric and antisymmetric modes are examined. The coherent transfer experiments are used to address the nature of inhomogeneous

  10. A stable room-temperature sodium-sulfur battery

    NASA Astrophysics Data System (ADS)

    Wei, Shuya; Xu, Shaomao; Agrawral, Akanksha; Choudhury, Snehashis; Lu, Yingying; Tu, Zhengyuan; Ma, Lin; Archer, Lynden A.

    2016-06-01

    High-energy rechargeable batteries based on earth-abundant materials are important for mobile and stationary storage technologies. Rechargeable sodium-sulfur batteries able to operate stably at room temperature are among the most sought-after platforms because such cells take advantage of a two-electron-redox process to achieve high storage capacity from inexpensive electrode materials. Here we report a room-temperature sodium-sulfur battery that uses a microporous carbon-sulfur composite cathode, and a liquid carbonate electrolyte containing the ionic liquid 1-methyl-3-propylimidazolium-chlorate tethered to SiO2 nanoparticles. We show that these cells can cycle stably at a rate of 0.5 C (1 C=1675, mAh g-1) with 600 mAh g-1 reversible capacity and nearly 100% Coulombic efficiency. By means of spectroscopic and electrochemical analysis, we find that the particles form a sodium-ion conductive film on the anode, which stabilizes deposition of sodium. We also find that sulfur remains interred in the carbon pores and undergo solid-state electrochemical reactions with sodium ions.

  11. A stable room-temperature sodium-sulfur battery.

    PubMed

    Wei, Shuya; Xu, Shaomao; Agrawral, Akanksha; Choudhury, Snehashis; Lu, Yingying; Tu, Zhengyuan; Ma, Lin; Archer, Lynden A

    2016-01-01

    High-energy rechargeable batteries based on earth-abundant materials are important for mobile and stationary storage technologies. Rechargeable sodium-sulfur batteries able to operate stably at room temperature are among the most sought-after platforms because such cells take advantage of a two-electron-redox process to achieve high storage capacity from inexpensive electrode materials. Here we report a room-temperature sodium-sulfur battery that uses a microporous carbon-sulfur composite cathode, and a liquid carbonate electrolyte containing the ionic liquid 1-methyl-3-propylimidazolium-chlorate tethered to SiO2 nanoparticles. We show that these cells can cycle stably at a rate of 0.5 C (1 C=1675, mAh g(-1)) with 600 mAh g(-1) reversible capacity and nearly 100% Coulombic efficiency. By means of spectroscopic and electrochemical analysis, we find that the particles form a sodium-ion conductive film on the anode, which stabilizes deposition of sodium. We also find that sulfur remains interred in the carbon pores and undergo solid-state electrochemical reactions with sodium ions. PMID:27277345

  12. A stable room-temperature sodium–sulfur battery

    PubMed Central

    Wei, Shuya; Xu, Shaomao; Agrawral, Akanksha; Choudhury, Snehashis; Lu, Yingying; Tu, Zhengyuan; Ma, Lin; Archer, Lynden A.

    2016-01-01

    High-energy rechargeable batteries based on earth-abundant materials are important for mobile and stationary storage technologies. Rechargeable sodium–sulfur batteries able to operate stably at room temperature are among the most sought-after platforms because such cells take advantage of a two-electron-redox process to achieve high storage capacity from inexpensive electrode materials. Here we report a room-temperature sodium–sulfur battery that uses a microporous carbon–sulfur composite cathode, and a liquid carbonate electrolyte containing the ionic liquid 1-methyl-3-propylimidazolium-chlorate tethered to SiO2 nanoparticles. We show that these cells can cycle stably at a rate of 0.5 C (1 C=1675, mAh g−1) with 600 mAh g−1 reversible capacity and nearly 100% Coulombic efficiency. By means of spectroscopic and electrochemical analysis, we find that the particles form a sodium-ion conductive film on the anode, which stabilizes deposition of sodium. We also find that sulfur remains interred in the carbon pores and undergo solid-state electrochemical reactions with sodium ions. PMID:27277345

  13. Determination of trace glucose and forecast of human diseases by affinity adsorption solid substrate room temperature phosphorimetry based on Triticum valgaris lectin labeled with 4.0-generation dendrimers

    NASA Astrophysics Data System (ADS)

    Li, Zhiming; Zhu, Guohui; Liu, Jiaming; Lu, Qiaomei; Yang, Minlan; Wu, Hong; Shi, Xiumei; Chen, Xinhua

    2007-08-01

    A new phosphorescence labeling reagent Triton-100X-4.0G-D (4.0G-D refers to 4.0-generation dendrimers) was found. Quantitative specific affinity adsorption (AA) reaction between Triton-100X-4.0G-D-WGA and glucose (G) was carried out on the surface of nitrocellulose membrane (NCM), and the Δ Ip of the product of AA reaction was linear correlation to the content of G. Based on the facts above, a new method for the determination of trace G was established by WGA labeled with Triton-100X-4.0G-D affinity adsorption solid substrate room temperature phosphorimetry (Triton-100X-4.0G-D-WGA-AA-SS-RTP). This research showed that AA-SS-RTP for either direct method or sandwich method could combine very well the characteristics of both the high sensitivity of SS-RTP and the specificity of the AA reaction. Detection limits (LD) were 0.24 fg spot -1 for direct method and 0.18 fg spot -1 for sandwich method, indicating both of them were of high sensitivity. The method has been applied to the determination of the content of G in human serum, and the results were coincided with those obtained by glucose oxidize enzyme method. It can also be applied to forecast accurately some human diseases, such as primary hepatic carcinoma, cirrhosis, acute and chronic hepatitis, transfer hepatocellular, etc. Meanwhile, the mechanism for the determination of G with AA-SS-RTP was discussed.

  14. Room temperature to cryogenic electrical interface

    SciTech Connect

    Faris, S.M.

    1988-04-26

    A monolithic superconductive chip is described comprising: a. a substrate with a low temperature region and a high temperature region; b. a low temperature electronic circuit formed on the low temperature region and including an element which is superconductive when it has a temperature below a critical level; and c. electrical conductors formed on the substrate, the conductors being connected to the electronic circuit and traversing the substrate to the high temperature region.

  15. Room temperature and productivity in office work

    SciTech Connect

    Seppanen, O.; Fisk, W.J.; Lei, Q.H.

    2006-07-01

    Indoor temperature is one of the fundamental characteristics of the indoor environment. It can be controlled with a degree of accuracy dependent on the building and its HVAC system. The indoor temperature affects several human responses, including thermal comfort, perceived air quality, sick building syndrome symptoms and performance at work. In this study, we focused on the effects of temperature on performance at office work. We included those studies that had used objective indicators of performance that are likely to be relevant in office type work, such as text processing, simple calculations (addition, multiplication), length of telephone customer service time, and total handling time per customer for call-center workers. We excluded data from studies of industrial work performance. We calculated from all studies the percentage of performance change per degree increase in temperature, and statistically analyzed measured work performance with temperature. The results show that performance increases with temperature up to 21-22 C, and decreases with temperature above 23-24 C. The highest productivity is at temperature of around 22 C. For example, at the temperature of 30 C, the performance is only 91.1% of the maximum i.e. the reduction in performance is 8.9%.

  16. Fabrication method for a room temperature hydrogen sensor

    NASA Technical Reports Server (NTRS)

    Seal, Sudipta (Inventor); Shukla, Satyajit V. (Inventor); Ludwig, Lawrence (Inventor); Cho, Hyoung (Inventor)

    2011-01-01

    A sensor for selectively determining the presence and measuring the amount of hydrogen in the vicinity of the sensor. The sensor comprises a MEMS device coated with a nanostructured thin film of indium oxide doped tin oxide with an over layer of nanostructured barium cerate with platinum catalyst nanoparticles. Initial exposure to a UV light source, at room temperature, causes burning of organic residues present on the sensor surface and provides a clean surface for sensing hydrogen at room temperature. A giant room temperature hydrogen sensitivity is observed after making the UV source off. The hydrogen sensor of the invention can be usefully employed for the detection of hydrogen in an environment susceptible to the incursion or generation of hydrogen and may be conveniently used at room temperature.

  17. Detecting luminescence from triplet states of organic semiconductors at room temperatures using delayed electroluminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Aziz, Hany

    2014-08-01

    We demonstrate a unique approach for detecting luminescence from triplet states of organic materials in the solid state at room temperatures. The technique is based on measuring delayed electroluminescence from the material. The approach overcomes limitations of conventional spectroscopic techniques, such as the need for cooling to cryogenic temperatures, and works for a wide range of organic materials. The underlying mechanisms behind observing materials phosphorescence using this technique are studied. The results show that using a low concentration of the target material doped in a host material and a large energy differences between triplet states of target and host materials are necessary for obtaining efficient phosphorescence at room temperatures.

  18. Room-temperature observations of the weak localization in low-mobility graphene films

    SciTech Connect

    Han, Junhao; Wang, Shanyue; Qian, Di; Song, Fengqi E-mail: bgwang@nju.edu.cn; Wang, Baigeng E-mail: bgwang@nju.edu.cn; Han, Min; Zhou, Jianfeng; Wang, Xinran; Wang, Xuefeng

    2013-12-07

    We report room-temperature observations of the quantum conductance corrections caused by the weak localization in graphene films synthesized using solid-state-source chemical vapor deposition. Both Raman spectroscopy and Hall measurements showed strong disorder in the samples with a low mobility of ∼430 cm{sup 2}/V s. The emergence of weak localization at room temperature arises from the competition between the valley-dependent scattering and the thermal dephasing in such low-quality samples, although quantum effects normally appear in the samples that have an ideal structure at cryogenic temperatures. The large disorder in our low-mobility samples unexpectedly preserved the quantum mechanical weak localization.

  19. Room-Temperature Magnetism Realized by Doping Fe into Ferroelectric LiTaO3

    NASA Astrophysics Data System (ADS)

    Song, Ying-Jie; Zhang, Qing-Hua; Shen, Xi; Ni, Xiao-Dong; Yao, Yuan; Yu, Ri-Cheng

    2014-01-01

    We synthesize LiTa1-xFexO3-σ (LTFO) ceramics by the conventional solid-state reaction method. The samples remain single phase up to x = 0.09. The magnetic measurements show that the doping of Fe successfully realizes ferromagnetism of LTFO at room temperature. The dielectric measurements indicate that LTFO is ferroelectric, similarly to LiTaO3 (LTO), but its ferroelectric Curie temperature seems to decrease with the increasing Fe content. By means of doping Fe ions into LTO, the coexistence of spontaneous electric polarization and spontaneous magnetic moment is realized at room temperature.

  20. Neutron absorbing room temperature vulcanizable silicone rubber compositions

    DOEpatents

    Zoch, Harold L.

    1979-11-27

    A neutron absorbing composition comprising a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysiloxane polymer of a boron compound or boron powder as the neutron absorbing ingredient. An especially useful boron compound in this application is boron carbide.

  1. Room temperature triplet state spectroscopy of organic semiconductors

    NASA Astrophysics Data System (ADS)

    Reineke, Sebastian; Baldo, Marc A.

    2014-01-01

    Organic light-emitting devices and solar cells are devices that create, manipulate, and convert excited states in organic semiconductors. It is crucial to characterize these excited states, or excitons, to optimize device performance in applications like displays and solar energy harvesting. This is complicated if the excited state is a triplet because the electronic transition is `dark' with a vanishing oscillator strength. As a consequence, triplet state spectroscopy must usually be performed at cryogenic temperatures to reduce competition from non-radiative rates. Here, we control non-radiative rates by engineering a solid-state host matrix containing the target molecule, allowing the observation of phosphorescence at room temperature and alleviating constraints of cryogenic experiments. We test these techniques on a wide range of materials with functionalities spanning multi-exciton generation (singlet exciton fission), organic light emitting device host materials, and thermally activated delayed fluorescence type emitters. Control of non-radiative modes in the matrix surrounding a target molecule may also have broader applications in light-emitting and photovoltaic devices.

  2. Room temperature triplet state spectroscopy of organic semiconductors

    PubMed Central

    Reineke, Sebastian; Baldo, Marc A.

    2014-01-01

    Organic light-emitting devices and solar cells are devices that create, manipulate, and convert excited states in organic semiconductors. It is crucial to characterize these excited states, or excitons, to optimize device performance in applications like displays and solar energy harvesting. This is complicated if the excited state is a triplet because the electronic transition is ‘dark’ with a vanishing oscillator strength. As a consequence, triplet state spectroscopy must usually be performed at cryogenic temperatures to reduce competition from non-radiative rates. Here, we control non-radiative rates by engineering a solid-state host matrix containing the target molecule, allowing the observation of phosphorescence at room temperature and alleviating constraints of cryogenic experiments. We test these techniques on a wide range of materials with functionalities spanning multi-exciton generation (singlet exciton fission), organic light emitting device host materials, and thermally activated delayed fluorescence type emitters. Control of non-radiative modes in the matrix surrounding a target molecule may also have broader applications in light-emitting and photovoltaic devices. PMID:24445870

  3. Thermal Effect in Opal Below Room Temperature

    PubMed Central

    Buerger, Martin J.; Shoemaker, Gerald L.

    1972-01-01

    Opal, once believed to be amorphous silica, was shown by Levin and Ott (1932, J. Amer. Chem. Soc. 54, 828-829) to give an x-ray powder pattern of the high-temperature form of cristobalite. The early explanation of this anomalous existence of a phase below its high-low transition temperature is now known to be untenable. One of us suggested that the tiny sizes of the component cristobalite crystals might explain the anomaly; if so, the transition might be expected below ambient temperatures. The record of a du Pont 900 Thermoanalyzer indeed revealed heat effects in opal below ambient temperatures, with an exotherm having a maximum at about -40° on cooling and an endotherm that began about -50° on heating. This was not a latent-heat effect due to the high-low transition of cristobalite, however, for the low-cristobalite pattern persisted to below -50°. Opal normally contains 4-9% water, which is tenaciously held; water loss is nearly linear with temperatures up to about 422°, when water loss is abruptly complete. Water-free opal does not display the thermal effect, but the same opal rehydrated does display it. Water is housed in minute voids, judged to be a few hundred Ångströms across, between minute particles of cristobalite. This water behaves differently from water in bulk, for its begins to melt at about -50°. PMID:16592025

  4. Control and Room Temperature Optimization of Energy Efficient Buildings

    SciTech Connect

    Djouadi, Seddik M; Kuruganti, Phani Teja

    2012-01-01

    The building sector consumes a large part of the energy used in the United States and is responsible for nearly 40% of greenhouse gas emissions. It is therefore economically and environmentally important to reduce the building energy consumption to realize massive energy savings. In this paper, a method to control room temperature in buildings is proposed. The approach is based on a distributed parameter model represented by a three dimensional (3D) heat equation in a room with heater/cooler located at ceiling. The latter is resolved using finite element methods, and results in a model for room temperature with thousands of states. The latter is not amenable to control design. A reduced order model of only few states is then derived using Proper Orthogonal Decomposition (POD). A Linear Quadratic Regulator (LQR) is computed based on the reduced model, and applied to the full order model to control room temperature.

  5. Nature of room-temperature photoluminescence in ZnO

    SciTech Connect

    Shan, W.; Walukiewicz, W.; Ager III, J.W.; Yu, K.M.; Yuan, H.B.; Xin, H.P.; Cantwell, G.; Song, J.J.

    2004-11-11

    The temperature dependence of the photoluminescence (PL) transitions associated with various excitons and their phonon replicas in high-purity bulk ZnO has been studied at temperatures from 12 K to above room temperature (320 K). Several strong PL emission lines associated with LO phonon replicas of free and bound excitons are clearly observed. The room temperature PL spectrum is dominated by the phonon replicas of the free exciton transition with the maximum at the first LO phonon replica. The results explain the discrepancy between the transition energy of free exciton determined by reflection measurement and the peak position obtained by the PL measurement.

  6. Solid rocket motor temperature sensitivity

    SciTech Connect

    Osborn, J.R.; Heister, S.D.

    1994-11-01

    The temperature sensitivity of the propellant and the solid rocket motor are described by several different temperature sensitivity coefficients. This enabled the derivation of three different relationships for the temperature sensitivity coefficient pi(sub K). To demonstrate this, two different propellants were used wherein the values of pi(sub K) were generated and compared. It was observed that the expressions are of equal complexity and offer ease of use. All involve only the burning rate data and the use of the parameters in St. Roberts burning rate low. It is also suggested that the most general expression for the sensitivity coefficient should be used since it is a true pi(sub K) relationship having the partial derivatives taken with the motor geometry held constant. 11 refs.

  7. Mesophases in nearly 2D room-temperature ionic liquids.

    PubMed

    Manini, N; Cesaratto, M; Del Pópolo, M G; Ballone, P

    2009-11-26

    Computer simulations of (i) a [C(12)mim][Tf(2)N] film of nanometric thickness squeezed at kbar pressure by a piecewise parabolic confining potential reveal a mesoscopic in-plane density and composition modulation reminiscent of mesophases seen in 3D samples of the same room-temperature ionic liquid (RTIL). Near 2D confinement, enforced by a high normal load, as well as relatively long aliphatic chains are strictly required for the mesophase formation, as confirmed by computations for two related systems made of (ii) the same [C(12)mim][Tf(2)N] adsorbed at a neutral solid surface and (iii) a shorter-chain RTIL ([C(4)mim][Tf(2)N]) trapped in the potential well of part i. No in-plane modulation is seen for ii and iii. In case ii, the optimal arrangement of charge and neutral tails is achieved by layering parallel to the surface, while, in case iii, weaker dispersion and packing interactions are unable to bring aliphatic tails together into mesoscopic islands, against overwhelming entropy and Coulomb forces. The onset of in-plane mesophases could greatly affect the properties of long-chain RTILs used as lubricants. PMID:19886615

  8. Direct On-Surface Patterning of a Crystalline Laminar Covalent Organic Framework Synthesized at Room Temperature.

    PubMed

    de la Peña Ruigómez, Alejandro; Rodríguez-San-Miguel, David; Stylianou, Kyriakos C; Cavallini, Massimiliano; Gentili, Denis; Liscio, Fabiola; Milita, Silvia; Roscioni, Otello Maria; Ruiz-González, Maria Luisa; Carbonell, Carlos; Maspoch, Daniel; Mas-Ballesté, Rubén; Segura, José Luis; Zamora, Félix

    2015-07-20

    We report herein an efficient, fast, and simple synthesis of an imine-based covalent organic framework (COF) at room temperature (hereafter, RT-COF-1). RT-COF-1 shows a layered hexagonal structure exhibiting channels, is robust, and is porous to N2 and CO2 . The room-temperature synthesis has enabled us to fabricate and position low-cost micro- and submicropatterns of RT-COF-1 on several surfaces, including solid SiO2 substrates and flexible acetate paper, by using lithographically controlled wetting and conventional ink-jet printing. PMID:26095511

  9. Room temperature DNA storage with slide-mounted Aphid specimens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most of the conventional molecular studies of aphids destroy the specimen in order to extract DNA. This DNA is subsequently stored in low temperature freezers. Room temperature storage of DNA with microscope slide-mounted voucher material is demonstrated by developing a system that uses filter pa...

  10. Acoustic method for measuring air temperature and humidity in rooms

    NASA Astrophysics Data System (ADS)

    Kanev, N. G.

    2014-05-01

    A method is proposed to determine air temperature and humidity in rooms with a system of sound sources and receivers, making it possible to find the sound velocity and reverberation time. Nomograms for determining the air temperature and relative air humidity are constructed from the found sound velocity and time reverberation values. The required accuracy of measuring these parameters is estimated.

  11. Room temperature ferromagnetism in Teflon due to carbon dangling bonds

    NASA Astrophysics Data System (ADS)

    Ma, Y. W.; Lu, Y. H.; Yi, J. B.; Feng, Y. P.; Herng, T. S.; Liu, X.; Gao, D. Q.; Xue, D. S.; Xue, J. M.; Ouyang, J. Y.; Ding, J.

    2012-03-01

    The ferromagnetism in many carbon nanostructures is attributed to carbon dangling bonds or vacancies. This provides opportunities to develop new functional materials, such as molecular and polymeric ferromagnets and organic spintronic materials, without magnetic elements (for example, 3d and 4f metals). Here we report the observation of room temperature ferromagnetism in Teflon tape (polytetrafluoroethylene) subjected to simple mechanical stretching, cutting or heating. First-principles calculations indicate that the room temperature ferromagnetism originates from carbon dangling bonds and strong ferromagnetic coupling between them. Room temperature ferromagnetism has also been successfully realized in another polymer, polyethylene, through cutting and stretching. Our findings suggest that ferromagnetism due to networks of carbon dangling bonds can arise in polymers and carbon-based molecular materials.

  12. Bulk nuclear polarization enhanced at room temperature by optical pumping.

    PubMed

    Fischer, Ran; Bretschneider, Christian O; London, Paz; Budker, Dmitry; Gershoni, David; Frydman, Lucio

    2013-08-01

    Bulk (13)C polarization can be strongly enhanced in diamond at room temperature based on the optical pumping of nitrogen-vacancy color centers. This effect was confirmed by irradiating single crystals at a ~50 mT field promoting anticrossings between electronic excited-state levels, followed by shuttling of the sample into an NMR setup and by subsequent (13)C detection. A nuclear polarization of ~0.5%--equivalent to the (13)C polarization achievable by thermal polarization at room temperature at fields of ~2000 T--was measured, and its bulk nature determined based on line shape and relaxation measurements. Positive and negative enhanced polarizations were obtained, with a generally complex but predictable dependence on the magnetic field during optical pumping. Owing to its simplicity, this (13)C room temperature polarizing strategy provides a promising new addition to existing nuclear hyperpolarization techniques. PMID:23952444

  13. Giant room-temperature elastocaloric effect in ferroelectric ultrathin films.

    PubMed

    Liu, Yang; Infante, Ingrid C; Lou, Xiaojie; Bellaiche, Laurent; Scott, James F; Dkhil, Brahim

    2014-09-17

    Environmentally friendly ultrathin BaTiO3 capacitors can exhibit a giant stress-induced elastocaloric effect without hysteresis loss or Joule heating. By combining this novel elastocaloric effect with the intrinsic electrocaloric effect, an ideal refrigeration cycle with high performance (temperature change over 10 K with a wide working-temperature window of 60 K) at room temperature is proposed for future cooling applications. PMID:25042767

  14. Nanostructured Materials for Room-Temperature Gas Sensors.

    PubMed

    Zhang, Jun; Liu, Xianghong; Neri, Giovanni; Pinna, Nicola

    2016-02-01

    Sensor technology has an important effect on many aspects in our society, and has gained much progress, propelled by the development of nanoscience and nanotechnology. Current research efforts are directed toward developing high-performance gas sensors with low operating temperature at low fabrication costs. A gas sensor working at room temperature is very appealing as it provides very low power consumption and does not require a heater for high-temperature operation, and hence simplifies the fabrication of sensor devices and reduces the operating cost. Nanostructured materials are at the core of the development of any room-temperature sensing platform. The most important advances with regard to fundamental research, sensing mechanisms, and application of nanostructured materials for room-temperature conductometric sensor devices are reviewed here. Particular emphasis is given to the relation between the nanostructure and sensor properties in an attempt to address structure-property correlations. Finally, some future research perspectives and new challenges that the field of room-temperature sensors will have to address are also discussed. PMID:26662346

  15. Electron spin coherence near room temperature in magnetic quantum dots.

    PubMed

    Moro, Fabrizio; Turyanska, Lyudmila; Wilman, James; Fielding, Alistair J; Fay, Michael W; Granwehr, Josef; Patanè, Amalia

    2015-01-01

    We report on an example of confined magnetic ions with long spin coherence near room temperature. This was achieved by confining single Mn(2+) spins in colloidal semiconductor quantum dots (QDs) and by dispersing the QDs in a proton-spin free matrix. The controlled suppression of Mn-Mn interactions and minimization of Mn-nuclear spin dipolar interactions result in unprecedentedly long phase memory (TM ~ 8 μs) and spin-lattice relaxation (T1 ~ 10 ms) time constants for Mn(2+) ions at T = 4.5 K, and in electron spin coherence observable near room temperature (TM ~ 1 μs). PMID:26040432

  16. Ultrahigh magnetoresistance at room temperature in molecular wires.

    PubMed

    Mahato, R N; Lülf, H; Siekman, M H; Kersten, S P; Bobbert, P A; de Jong, M P; De Cola, L; van der Wiel, W G

    2013-07-19

    Systems featuring large magnetoresistance (MR) at room temperature and in small magnetic fields are attractive owing to their potential for applications in magnetic field sensing and data storage. Usually, the magnetic properties of materials are exploited to achieve large MR effects. Here, we report on an exceptionally large (>2000%), room-temperature, small-field (a few millitesla) MR effect in one-dimensional, nonmagnetic systems formed by molecular wires embedded in a zeolite host crystal. This ultrahigh MR effect is ascribed to spin blockade in one-dimensional electron transport. Its generic nature offers very good perspectives to exploit the effect in a wide range of low-dimensional systems. PMID:23828887

  17. Trace vapour detection at room temperature using Raman spectroscopy.

    PubMed

    Chou, Alison; Radi, Babak; Jaatinen, Esa; Juodkazis, Saulius; Fredericks, Peter M

    2014-04-21

    A miniaturized flow-through system consisting of a gold coated silicon substrate based on enhanced Raman spectroscopy has been used to study the detection of vapour from model explosive compounds. The measurements show that the detectability of the vapour molecules at room temperature depends sensitively on the interaction between the molecule and the substrate. The results highlight the capability of a flow system combined with Raman spectroscopy for detecting low vapour pressure compounds with a limit of detection of 0.2 ppb as demonstrated by the detection of bis(2-ethylhexyl)phthalate, a common polymer additive emitted from a commercial polyvinyl chloride (PVC) tubing at room temperature. PMID:24588003

  18. Ether-based nonflammable electrolyte for room temperature sodium battery

    NASA Astrophysics Data System (ADS)

    Feng, Jinkui; Zhang, Zhen; Li, Lifei; Yang, Jian; Xiong, Shenglin; Qian, Yitai

    2015-06-01

    Safety problem is one of the key points that hinder the development of room temperature sodium batteries. In this paper, four well-known nonflammable organic compounds, Trimethyl Phosphate (TMP), Tri(2,2,2-trifluoroethyl) phosphite (TFEP), Dimethyl Methylphosphonate (DMMP), Methyl nonafluorobuyl Ether (MFE), are investigated as nonflammable solvents in sodium batteries for the first time. Among them, MFE is stable towards sodium metal at room temperature. The electrochemical properties and electrode compatibility of MFE based electrolyte are investigated. Both Prussian blue cathode and carbon nanotube anode show good electrochemical performance retention in this electrolyte. The results suggest that MFE is a promising option as nonflammable electrolyte additive for sodium batteries.

  19. High temperature solid state storage cell

    SciTech Connect

    Rea, Jesse R.; Kallianidis, Milton; Kelsey, G. Stephen

    1983-01-01

    A completely solid state high temperature storage cell comprised of a solid rechargeable cathode such as TiS.sub.2, a solid electrolyte which remains solid at the high temperature operating conditions of the cell and which exhibits high ionic conductivity at such elevated temperatures such as an electrolyte comprised of lithium iodide, and a solid lithium or other alkali metal alloy anode (such as a lithium-silicon alloy) with 5-50% by weight of said anode being comprised of said solid electrolyte.

  20. Efficient room-temperature Spin Hall nano-oscillator

    NASA Astrophysics Data System (ADS)

    Zholud, Andrei; Urazhdin, Sergei

    2014-03-01

    Spin current injected into a ferromagnet exerts a spin torque on the magnetization, modifying its dynamical damping. Complete compensation of damping by spin current can result in magnetization auto-oscillations, as was demonstrated for in-plane point-contact spin Hall oscillator devices utilizing Pt spin Hall material as a source of spin current and permalloy (Py) as active magnetic layer. Electronic spectroscopy has demonstrated microwave generation by oscillations of magnetization at cryogenic temperatures, but this microwave generation decreases with increasing temperature and disappears at room temperature. We will describe a new device geometry that decouples spin transport from the magnetic configuration by separate patterning of the spin Hall Pt layer and the active Py layer. We demonstrate that this device geometry can operate at smaller driving dc currents for microwave generation that persists up to room temperature. We discuss the physical mechanisms that affect the temperature- and geometry-dependent performance of spin Hall nano-oscillators.

  1. Room-Temperature-Cured Copolymers for Lithium Battery Gel Electrolytes

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Tigelaar, Dean M.

    2009-01-01

    Polyimide-PEO copolymers (PEO signifies polyethylene oxide) that have branched rod-coil molecular structures and that can be cured into film form at room temperature have been invented for use as gel electrolytes for lithium-ion electric-power cells. These copolymers offer an alternative to previously patented branched rod-coil polyimides that have been considered for use as polymer electrolytes and that must be cured at a temperature of 200 C. In order to obtain sufficient conductivity for lithium ions in practical applications at and below room temperature, it is necessary to imbibe such a polymer with a suitable carbonate solvent or ionic liquid, but the high-temperature cure makes it impossible to incorporate and retain such a liquid within the polymer molecular framework. By eliminating the high-temperature cure, the present invention makes it possible to incorporate the required liquid.

  2. Room temperature ferromagnetic (Fe₁-xCox)₃BO₅ nanorods.

    PubMed

    He, Shuli; Zhang, Hongwang; Xing, Hui; Li, Kai; Cui, Hongfei; Yang, Chenguang; Sun, Shouheng; Zeng, Hao

    2014-07-01

    Cobalt-doped ferroferriborate ((Fe1-xCox)3BO5) nanorods (NRs) are synthesized by a one-pot high-temperature organic-solution-phase method. The aspect ratios of the NRs are tuned by the heating rate. These NRs form via anisotropic growth along twin boundaries of the multiply twinned nuclei. Magnetic properties are dramatically modified by Co substitutional doping, changing from antiferromagnetic order at low temperatures to ferromagnetic above room temperature, with a greatly enhanced magnetic ordering temperature. These anisotropic ferromagnetic NRs with a high ordering temperature may provide a new platform for understanding nanomagnetism and for magnetic applications. PMID:24905634

  3. Protocols for dry DNA storage and shipment at room temperature

    PubMed Central

    Ivanova, Natalia V; Kuzmina, Masha L

    2013-01-01

    The globalization of DNA barcoding will require core analytical facilities to develop cost-effective, efficient protocols for the shipment and archival storage of DNA extracts and PCR products. We evaluated three dry-state DNA stabilization systems: commercial Biomatrica® DNAstable® plates, home-made trehalose and polyvinyl alcohol (PVA) plates on 96-well panels of insect DNA stored at 56 °C and at room temperature. Controls included unprotected samples that were stored dry at room temperature and at 56 °C, and diluted samples held at 4 °C and at −20 °C. PCR and selective sequencing were performed over a 4-year interval to test the condition of DNA extracts. Biomatrica® provided better protection of DNA at 56 °C and at room temperature than trehalose and PVA, especially for diluted samples. PVA was the second best protectant after Biomatrica® at room temperature, whereas trehalose was the second best protectant at 56 °C. In spite of lower PCR success, the DNA stored at −20 °C yielded longer sequence reads and stronger signal, indicating that temperature is a crucial factor for DNA quality which has to be considered especially for long-term storage. Although it is premature to advocate a transition to DNA storage at room temperature, dry storage provides an additional layer of security for frozen samples, protecting them from degradation in the event of freezer failure. All three forms of DNA preservation enable shipment of dry DNA and PCR products between barcoding facilities. PMID:23789643

  4. SPRAY: Single Donor Plasma Product For Room Temperature Storage

    PubMed Central

    Booth, Garrett S.; Lozier, Jay N.; Nghiem, Khanh; Clibourn, Douglas; Klein, Harvey G.; Flegel, Willy A.

    2013-01-01

    Background Spray drying techniques are commonly utilized in the pharmaceutical, dairy and animal feed industries for processing liquids into powders but have not been applied to human blood products. Spray dried protein products are known to maintain stability during storage at room temperature. Study design and methods Plasma units collected at the donor facility were shipped overnight at room temperature to a processing facility where single-use spray drying occurred. After 48 hours storage at room temperature, the spray dried plasma product was split in two and rehydrated with 1.5% glycine or deionized water and assayed for chemistry analytes and coagulation factors. Matched fresh frozen plasma (FFP) was analyzed in parallel as controls. Results Reconstitution was achieved for both rehydration groups within five minutes (n=6). There was no statistically significant intergroup difference in recovery for total protein, albumin, IgG, IgA, and IgM (96% or higher). With the exception of factor VIII (58%), the recovery of clotting factors in the glycine reconstituted products ranged from 72% to 93%. Glycine reconstitution was superior to deionized water. Conclusion We documented proteins and coagulation activities were recovered in physiologic quantities in reconstituted spray dried plasma products. Further optimization of the spray drying method and reconstitution fluid may result in even better recoveries. Spray drying is a promising technique for preparing human plasma that can be easily stored at room temperature, shipped, and reconstituted. Rapid reconstitution of the microparticles results in a novel plasma product from single donors. PMID:22043873

  5. Reductions of aryl bromides in water at room temperature

    PubMed Central

    Fennewald, James C.; Landstrom, Evan B.; Lipshutz, Bruce H.

    2015-01-01

    Micellar nanoreactors derived from commercially available ‘Nok’ (SPGS-550-M), in the presence of Fu’s catalyst and a mild hydride source (NaBH4), are useful for facile debromination of functionalized aromatic derivatives. This mild and environemntally responsible process is utlized in water at room temperature, and the reaction mixtures can be smoothly recycled. PMID:26273116

  6. Room-Temperature Ionic Liquids for Electrochemical Capacitors

    NASA Technical Reports Server (NTRS)

    Fireman, Heather; Yowell, Leonard; Moloney, Padraig G.; Arepalli, Sivaram; Nikolaev, P.; Huffman, C.; Ready, Jud; Higgins, C.D.; Turano, S. P.; Kohl, P.A.; Kim, K.

    2009-01-01

    A document discusses room-temperature ionic liquids (RTILs) used as electrolytes in carbon-nanotube-based, electrochemical, double-layer capacitors. Unlike the previous electrolyte (EtNB4 in acetonitrile), the RTIL used here does not produce cyanide upon thermal decomposition and does not have a moisture sensitivity.

  7. Required Be Capsule Strength For Room Temperature Transport

    SciTech Connect

    Cook, B

    2005-03-21

    The purpose of this memo is to lay out the criteria for the Be capsule strength necessary for room temperature transport. Ultimately we will test full thickness capsules by sealing high pressures inside, but currently we are limited to both thinner capsules and alternative measures of capsule material strength.

  8. Halide-stabilized LiBH4, a room-temperature lithium fast-ion conductor.

    PubMed

    Maekawa, Hideki; Matsuo, Motoaki; Takamura, Hitoshi; Ando, Mariko; Noda, Yasuto; Karahashi, Taiki; Orimo, Shin-ichi

    2009-01-28

    Solid state lithium conductors are attracting much attention for their potential applications to solid-state batteries and supercapacitors of high energy density to overcome safety issues and irreversible capacity loss of the currently commercialized ones. Recently, we discovered a new class of lithium super ionic conductors based on lithium borohydride (LiBH(4)). LiBH(4) was found to have conductivity as high as 10(-2) Scm(-1) accompanied by orthorhombic to hexagonal phase transition above 115 degrees C. Polarization to the lithium metal electrode was shown to be extremely low, providing a versatile anode interface for the battery application. However, the high transition temperature of the superionic phase has limited its applications. Here we show that a chemical modification of LiBH(4) can stabilize the superionic phase even below room temperature. By doping of lithium halides, high conductivity can be obtained at room temperature. Both XRD and NMR confirmed room-temperature stabilization of superionic phase for LiI-doped LiBH(4). The electrochemical measurements showed a great advantage of this material as an extremely lightweight lithium electrolyte for batteries of high energy density. This material will open alternative opportunities for the development of solid ionic conductors other than previously known lithium conductors. PMID:19119813

  9. Evaluation of Ceramic Honeycomb Core Compression Behavior at Room Temperature

    NASA Technical Reports Server (NTRS)

    Bird, Richard K.; Lapointe, Thomas S.

    2013-01-01

    Room temperature flatwise compression tests were conducted on two varieties of ceramic honeycomb core specimens that have potential for high-temperature structural applications. One set of specimens was fabricated using strips of a commercially-available thin-gage "ceramic paper" sheet molded into a hexagonal core configuration. The other set was fabricated by machining honeycomb core directly from a commercially available rigid insulation tile material. This paper summarizes the results from these tests.

  10. Room temperature manipulation of long lifetime spins in metallic-like carbon nanospheres

    NASA Astrophysics Data System (ADS)

    Náfrádi, Bálint; Choucair, Mohammad; Dinse, Klaus-Peter; Forró, László

    2016-07-01

    The time-window for processing electron spin information (spintronics) in solid-state quantum electronic devices is determined by the spin-lattice and spin-spin relaxation times of electrons. Minimizing the effects of spin-orbit coupling and the local magnetic contributions of neighbouring atoms on spin-lattice and spin-spin relaxation times at room temperature remain substantial challenges to practical spintronics. Here we report conduction electron spin-lattice and spin-spin relaxation times of 175 ns at 300 K in 37+/-7 nm carbon spheres, which is remarkably long for any conducting solid-state material of comparable size. Following the observation of spin polarization by electron spin resonance, we control the quantum state of the electron spin by applying short bursts of an oscillating magnetic field and observe coherent oscillations of the spin state. These results demonstrate the feasibility of operating electron spins in conducting carbon nanospheres as quantum bits at room temperature.

  11. A highly reversible room-temperature lithium metal battery based on crosslinked hairy nanoparticles

    NASA Astrophysics Data System (ADS)

    Choudhury, Snehashis; Mangal, Rahul; Agrawal, Akanksha; Archer, Lynden A.

    2015-12-01

    Rough electrodeposition, uncontrolled parasitic side-reactions with electrolytes and dendrite-induced short-circuits have hindered development of advanced energy storage technologies based on metallic lithium, sodium and aluminium electrodes. Solid polymer electrolytes and nanoparticle-polymer composites have shown promise as candidates to suppress lithium dendrite growth, but the challenge of simultaneously maintaining high mechanical strength and high ionic conductivity at room temperature has so far been unmet in these materials. Here we report a facile and scalable method of fabricating tough, freestanding membranes that combine the best attributes of solid polymers, nanocomposites and gel-polymer electrolytes. Hairy nanoparticles are employed as multifunctional nodes for polymer crosslinking, which produces mechanically robust membranes that are exceptionally effective in inhibiting dendrite growth in a lithium metal battery. The membranes are also reported to enable stable cycling of lithium batteries paired with conventional intercalating cathodes. Our findings appear to provide an important step towards room-temperature dendrite-free batteries.

  12. High energy sodium based room temperature flow batteries

    NASA Astrophysics Data System (ADS)

    Shamie, Jack

    As novel energy sources such as solar, wind and tidal energies are explored it becomes necessary to build energy storage facilities to load level the intermittent nature of these energy sources. Energy storage is achieved by converting electrical energy into another form of energy. Batteries have many properties that are attractive for energy storage including high energy and power. Among many different types of batteries, redox flow batteries (RFBs) offer many advantages. Unlike conventional batteries, RFBs store energy in a liquid medium rather than solid active materials. This method of storage allows for the separation of energy and power unlike conventional batteries. Additionally flow batteries may have long lifetimes because there is no expansion or contraction of electrodes. A major disadvantage of RFB's is its lower energy density when compared to traditional batteries. In this Thesis, a novel hybrid Na-based redox flow battery (HNFB) is explored, which utilizes a room temperature molten sodium based anode, a sodium ion conducting solid electrolyte and liquid catholytes. The sodium electrode leads to high voltages and energy and allows for the possibility of multi-electron transfer per molecule. Vanadium acetylacetonate (acac) and TEMPO have been investigated for their use as catholytes. In the vanadium system, 2 electrons transfers per vanadium atom were found leading to a doubling of capacity. In addition, degradation of the charged state was found to be reversible within the voltage range of the cell. Contamination by water leads to the formation of vanadyl acetylacetonate. Although it is believed that vanadyl complex need to be taken to low voltages to be reduced back to vanadium acac, a new mechanism is shown that begins at higher voltages (2.1V). Vanadyl complexes react with excess ligand and protons to reform the vanadium complex. During this reaction, water is reformed leading to the continuous cycle in which vanadyl is formed and then reduced back

  13. Mechanical Resonators for Quantum Optomechanics Experiments at Room Temperature

    NASA Astrophysics Data System (ADS)

    Norte, R. A.; Moura, J. P.; Gröblacher, S.

    2016-04-01

    All quantum optomechanics experiments to date operate at cryogenic temperatures, imposing severe technical challenges and fundamental constraints. Here, we present a novel design of on-chip mechanical resonators which exhibit fundamental modes with frequencies f and mechanical quality factors Qm sufficient to enter the optomechanical quantum regime at room temperature. We overcome previous limitations by designing ultrathin, high-stress silicon nitride (Si3 N4 ) membranes, with tensile stress in the resonators' clamps close to the ultimate yield strength of the material. By patterning a photonic crystal on the SiN membranes, we observe reflectivities greater than 99%. These on-chip resonators have remarkably low mechanical dissipation, with Qm˜108, while at the same time exhibiting large reflectivities. This makes them a unique platform for experiments towards the observation of massive quantum behavior at room temperature.

  14. Room-temperature magnetoelectric multiferroic thin films and applications thereof

    SciTech Connect

    Katiyar, Ram S; Kuman, Ashok; Scott, James F.

    2014-08-12

    The invention provides a novel class of room-temperature, single-phase, magnetoelectric multiferroic (PbFe.sub.0.67W.sub.0.33O.sub.3).sub.x (PbZr.sub.0.53Ti.sub.0.47O.sub.3).sub.1-x (0.2.ltoreq.x.ltoreq.0.8) (PFW.sub.x-PZT.sub.1-x) thin films that exhibit high dielectric constants, high polarization, weak saturation magnetization, broad dielectric temperature peak, high-frequency dispersion, low dielectric loss and low leakage current. These properties render them to be suitable candidates for room-temperature multiferroic devices. Methods of preparation are also provided.

  15. Atom inlays performed at room temperature using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Sugimoto, Yoshiaki; Abe, Masayuki; Hirayama, Shinji; Oyabu, Noriaki; Custance, Óscar; Morita, Seizo

    2005-02-01

    The ability to manipulate single atoms and molecules laterally for creating artificial structures on surfaces is driving us closer to the ultimate limit of two-dimensional nanoengineering. However, experiments involving this level of manipulation have been performed only at cryogenic temperatures. Scanning tunnelling microscopy has proved, so far, to be a unique tool with all the necessary capabilities for laterally pushing, pulling or sliding single atoms and molecules, and arranging them on a surface at will. Here we demonstrate, for the first time, that it is possible to perform well-controlled lateral manipulations of single atoms using near-contact atomic force microscopy even at room temperature. We report the creation of 'atom inlays', that is, artificial atomic patterns formed from a few embedded atoms in the plane of a surface. At room temperature, such atomic structures remain stable on the surface for relatively long periods of time.

  16. Mechanical Resonators for Quantum Optomechanics Experiments at Room Temperature.

    PubMed

    Norte, R A; Moura, J P; Gröblacher, S

    2016-04-01

    All quantum optomechanics experiments to date operate at cryogenic temperatures, imposing severe technical challenges and fundamental constraints. Here, we present a novel design of on-chip mechanical resonators which exhibit fundamental modes with frequencies f and mechanical quality factors Q_{m} sufficient to enter the optomechanical quantum regime at room temperature. We overcome previous limitations by designing ultrathin, high-stress silicon nitride (Si_{3}N_{4}) membranes, with tensile stress in the resonators' clamps close to the ultimate yield strength of the material. By patterning a photonic crystal on the SiN membranes, we observe reflectivities greater than 99%. These on-chip resonators have remarkably low mechanical dissipation, with Q_{m}∼10^{8}, while at the same time exhibiting large reflectivities. This makes them a unique platform for experiments towards the observation of massive quantum behavior at room temperature. PMID:27104723

  17. Room Temperature Characterization of a Magnetic Bearing for Turbomachinery

    NASA Technical Reports Server (NTRS)

    Montague, Gerald; Jansen, Mark; Provenza, Andrew; Jansen, Ralph; Ebihara, Ben; Palazzolo, Alan

    2002-01-01

    Open loop, experimental force and power measurements of a three-axis, radial, heteropolar magnetic bearing at room temperature for rotor speeds up to 20,000 RPM are presented in this paper. The bearing, NASA Glenn Research Center's and Texas A&M's third generation high temperature magnetic bearing, was designed to operate in a 1000 F (540 C) environment and was primarily optimized for maximum load capacity. The experimentally measured force produced by one C-core of this bearing was 630 lb. (2.8 kN) at 16 A, while a load of 650 lbs (2.89 kN) was predicted at 16 A using 1D circuit analysis. The maximum predicted radial load for one of the three axes is 1,440 lbs (6.41 kN) at room temperature. The maximum measured load of an axis was 1050 lbs. (4.73 kN). Results of test under rotating conditions showed that rotor speed has a negligible effect on the bearing's load capacity. A single C-core required approximately 70 W of power to generate 300 lb (1.34 kN) of magnetic force. The room temperature data presented was measured after three thermal cycles up to 1000 F (540 C), totaling six hours at elevated temperatures.

  18. Robust isothermal electric control of exchange bias at room temperature

    NASA Astrophysics Data System (ADS)

    Binek, Christian

    2011-03-01

    Voltage-controlled spintronics is of particular importance to continue progress in information technology through reduced power consumption, enhanced processing speed, integration density, and functionality in comparison with present day CMOS electronics. Almost all existing and prototypical solid-state spintronic devices rely on tailored interface magnetism, enabling spin-selective transmission or scattering of electrons. Controlling magnetism at thin-film interfaces, preferably by purely electrical means, is a key challenge to better spintronics. Currently, most attempts to electrically control magnetism focus on potentially large magnetoelectric effects of multiferroics. We report on our interest in magnetoelectric Cr 2 O3 (chromia). Robust isothermal electric control of exchange bias is achieved at room temperature in perpendicular anisotropic Cr 2 O3 (0001)/CoPd exchange bias heterostructures. This discovery promises significant implications for potential spintronics. From the perspective of basic science, our finding serves as macroscopic evidence for roughness-insensitive and electrically controllable equilibrium boundary magnetization in magnetoelectric antiferromagnets. The latter evolves at chromia (0001) surfaces and interfaces when chromia is in one of its two degenerate antiferromagnetic single domain states selected via magnetoelectric annealing. Theoretical insight into the boundary magnetization and its role in electrically controlled exchange bias is gained from first-principles calculations and general symmetry arguments. Measurements of spin-resolved ultraviolet photoemission, magnetometry at Cr 2 O3 (0001) surfaces, and detailed investigations of the unique exchange bias properties of Cr 2 O3 (0001)/CoPd including its electric controllability provide macroscopically averaged information about the boundary magnetization of chromia. Laterally resolved X-ray PEEM and temperature dependent MFM reveal detailed microscopic information of the chromia

  19. Room-Temperature Deposition of NbN Superconducting Films

    NASA Technical Reports Server (NTRS)

    Thakoor, S.; Lamb, J. L.; Thakoor, A. P.; Khanna, S. K.

    1986-01-01

    Films with high superconducting transition temperatures deposited by reactive magnetron sputtering. Since deposition process does not involve significantly high substrate temperatures, employed to deposit counter electrode in superconductor/insulator/superconductor junction without causing any thermal or mechanical degradation of underlying delicate tunneling barrier. Substrates for room-temperature deposition of NbN polymeric or coated with photoresist, making films accessible to conventional lithographic patterning techniques. Further refinements in deposition technique yield films with smaller transition widths, Tc of which might approach predicted value of 18 K.

  20. One-Pot Synthesis of β-Acetamido Ketones Using Boric Acid at Room Temperature

    PubMed Central

    Karimi-Jaberi, Zahed; Mohammadi, Korosh

    2012-01-01

    β-acetamido ketones were synthesized in excellent yields through one-pot condensation reaction of aldehydes, acetophenones, acetyl chloride, and acetonitrile in the presence of boric acid as a solid heterogeneous catalyst at room temperature. It is the first successful report of boric acid that has been used as solid acid catalyst for the preparation of β-acetamido ketones. The remarkable advantages offered by this method are green catalyst, mild reaction conditions, simple procedure, short reaction times, and good-to-excellent yields of products. PMID:22666168

  1. Towards Room Temperature Spin Filtering in Oxide Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Iwata-Harms, Jodi; Wong, Franklin; Arenholz, Elke; Suzuki, Yuri

    2012-02-01

    Spin filtering, in which the magnetic tunnel barrier preferentially filters spin-up and spin-down electrons from a nonmagnetic electrode, has been demonstrated in junction heterostructures. By incorporating two spin filtering barriers, double spin filter magnetic tunnel junctions (DSF-MTJs) were predicted to yield magnetoresistance (MR) values orders of magnitude larger than that of conventional magnetic tunnel junctions. Recently, DSF-MTJs have exhibited spin filtering with magnetic electrodes at room temperature and at low temperature with nonmagnetic electrodes in EuS-based devices [1,2]. We have fabricated DSF-MTJs with nonmagnetic SrRuO3 electrodes and room temperature ferrimagnets, NiFe2O4 and CoFe2O4, for spin filters in pursuit of room temperature functionality. Atomic force microscopy shows smooth films quantified by roughness values between 0.1--0.5nm. X-ray magnetic circular dichroism reveals ferromagnetic Ni^2+ and Co^2+, and element-specific hysteresis loops indicate the independent switching of the two spin filters. Transport data reveals junction MR and non-linear I-V characteristics consistent with tunneling. [4pt] [1] M.G. Chapline et al., PRB, 74, 014418 (2006).[0pt] [2] G.- X. Miao et al., PRL, 102, 076601 (2009).

  2. Single-electron tunneling at room temperature in cobalt nanoparticles

    NASA Astrophysics Data System (ADS)

    Graf, H.; Vancea, J.; Hoffmann, H.

    2002-02-01

    We report on the observation of the Coulomb blockade with Coulomb staircases at room temperature in cobalt nanoparticles, with sizes ranging between 1 and 4 nm. A monolayer of these particles is supported by a thin 1-2 nm thick Al2O3 film, deposited on a smooth Au(111) surface. The local electrical transport on isolated Co clusters was investigated with a scanning tunneling microscope (STM). The tunnel contact of the STM tip allowed us to observe single-electron tunneling in the double barrier system STM-tip/Co/Al2O3/Au. Very high values of the Coulomb blockade of up to 1.0 V were reproducibly measured at room temperature on different particles with this setup. The current-voltage characteristics fit well by simulations based on the orthodox theory of single-electron tunneling.

  3. Stability of blood gases in ice and at room temperature.

    PubMed

    Liss, H P; Payne, C P

    1993-04-01

    Arterial blood samples from 75 patients were analyzed for PO2, PCO2, and pH at 0, 15, and 30 min. After the baseline analysis, 60 samples were kept in ice while 59 samples were left at room temperature. There was a statistically significant increase in the PO2 at 15 min and again at 30 min in both groups. There was a statistically significant decrease in the PCO2 at 15 min in both groups. There were no further changes in the PCO2 at 30 min in either group. There was a statistically significant decrease in the pH at 15 min in both groups. There was a further statistically significant decrease in the pH at 30 min in the group of blood samples left at room temperature but not in those in ice. There is no reason to keep arterial blood in ice if blood gas analysis is done within 30 min. PMID:8131450

  4. Room temperature hyperpolarization of nuclear spins in bulk

    PubMed Central

    Tateishi, Kenichiro; Negoro, Makoto; Nishida, Shinsuke; Kagawa, Akinori; Morita, Yasushi; Kitagawa, Masahiro

    2014-01-01

    Dynamic nuclear polarization (DNP), a means of transferring spin polarization from electrons to nuclei, can enhance the nuclear spin polarization (hence the NMR sensitivity) in bulk materials at most 660 times for 1H spins, using electron spins in thermal equilibrium as polarizing agents. By using electron spins in photo-excited triplet states instead, DNP can overcome the above limit. We demonstrate a 1H spin polarization of 34%, which gives an enhancement factor of 250,000 in 0.40 T, while maintaining a bulk sample (∼0.6 mg, ∼0.7 × 0.7 × 1 mm3) containing >1019 1H spins at room temperature. Room temperature hyperpolarization achieved with DNP using photo-excited triplet electrons has potentials to be applied to a wide range of fields, including NMR spectroscopy and MRI as well as fundamental physics. PMID:24821773

  5. Enhanced magnetic Purcell effect in room-temperature masers.

    PubMed

    Breeze, Jonathan; Tan, Ke-Jie; Richards, Benjamin; Sathian, Juna; Oxborrow, Mark; Alford, Neil McN

    2015-01-01

    Recently, the world's first room-temperature maser was demonstrated. The maser consisted of a sapphire ring housing a crystal of pentacene-doped p-terphenyl, pumped by a pulsed rhodamine-dye laser. Stimulated emission of microwaves was aided by the high quality factor and small magnetic mode volume of the maser cavity yet the peak optical pumping power was 1.4 kW. Here we report dramatic miniaturization and 2 orders of magnitude reduction in optical pumping power for a room-temperature maser by coupling a strontium titanate resonator with the spin-polarized population inversion provided by triplet states in an optically excited pentacene-doped p-terphenyl crystal. We observe maser emission in a thimble-sized resonator using a xenon flash lamp as an optical pump source with peak optical power of 70 W. This is a significant step towards the goal of continuous maser operation. PMID:25698634

  6. Disorder-induced Room Temperature Ferromagnetism in Glassy Chromites

    PubMed Central

    Araujo, C. Moyses; Nagar, Sandeep; Ramzan, Muhammad; Shukla, R.; Jayakumar, O. D.; Tyagi, A. K.; Liu, Yi-Sheng; Chen, Jeng-Lung; Glans, Per-Anders; Chang, Chinglin; Blomqvist, Andreas; Lizárraga, Raquel; Holmström, Erik; Belova, Lyubov; Guo, Jinghua; Ahuja, Rajeev; Rao, K. V.

    2014-01-01

    We report an unusual robust ferromagnetic order above room temperature upon amorphization of perovskite [YCrO3] in pulsed laser deposited thin films. This is contrary to the usual expected formation of a spin glass magnetic state in the resulting disordered structure. To understand the underlying physics of this phenomenon, we combine advanced spectroscopic techniques and first-principles calculations. We find that the observed order-disorder transformation is accompanied by an insulator-metal transition arising from a wide distribution of Cr-O-Cr bond angles and the consequent metallization through free carriers. Similar results also found in YbCrO3-films suggest that the observed phenomenon is more general and should, in principle, apply to a wider range of oxide systems. The ability to tailor ferromagnetic order above room temperature in oxide materials opens up many possibilities for novel technological applications of this counter intuitive effect. PMID:24732685

  7. Primary and secondary room temperature molten salt electrochemical cells

    NASA Astrophysics Data System (ADS)

    Reynolds, G. F.; Dymek, C. J., Jr.

    1985-07-01

    Three novel primary cells which use room temperature molten salt electrolytes are examined and found to have high open circuit potentials in the 1.75-2.19 V range, by comparison with the Al/AlCl3-MEICl concentration cell; their cathodes were of FeCl3-MEICl, WCl6-MEICl, and Br2/reticulated vitreous carbon together with Pt. Also, secondary electrochemical cell candidates were examined which combined the reversible Al/AlCl3-MEICl electrode with reversible zinc and cadmium molten salt electrodes to yield open circuit potentials of about 0.7 and 1.0 V, respectively. Room temperature molten salts' half-cell reduction potentials are given.

  8. Room temperature particle detectors based on indium phosphide

    NASA Astrophysics Data System (ADS)

    Yatskiv, R.; Grym, J.; Zdansky, K.; Pekarek, L.

    2010-01-01

    A study of electrical properties and detection performance of particle detectors based on bulk InP and semiconducting LPE layers operated at room temperature is presented. Bulk detectors were fabricated on semi-insulating InP crystals grown by liquid-encapsulated Czochralski (LEC) technique. High purity InP layers of both n- and p-type conductivity were used to fabricate detector structures with p-n junction. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from 241Am source at room temperature. Better noise properties were achieved for detectors with p-n junctions due to better quality contacts on p-type layers.

  9. Outrunning free radicals in room-temperature macromolecular crystallography

    PubMed Central

    Owen, Robin L.; Axford, Danny; Nettleship, Joanne E.; Owens, Raymond J.; Robinson, James I.; Morgan, Ann W.; Doré, Andrew S.; Lebon, Guillaume; Tate, Christopher G.; Fry, Elizabeth E.; Ren, Jingshan; Stuart, David I.; Evans, Gwyndaf

    2012-01-01

    A significant increase in the lifetime of room-temperature macromolecular crystals is reported through the use of a high-brilliance X-ray beam, reduced exposure times and a fast-readout detector. This is attributed to the ability to collect diffraction data before hydroxyl radicals can propagate through the crystal, fatally disrupting the lattice. Hydroxyl radicals are shown to be trapped in amorphous solutions at 100 K. The trend in crystal lifetime was observed in crystals of a soluble protein (immunoglobulin γ Fc receptor IIIa), a virus (bovine enterovirus serotype 2) and a membrane protein (human A2A adenosine G-protein coupled receptor). The observation of a similar effect in all three systems provides clear evidence for a common optimal strategy for room-temperature data collection and will inform the design of future synchrotron beamlines and detectors for macro­molecular crystallography. PMID:22751666

  10. Enhanced magnetic Purcell effect in room-temperature masers

    PubMed Central

    Breeze, Jonathan; Tan, Ke-Jie; Richards, Benjamin; Sathian, Juna; Oxborrow, Mark; Alford, Neil McN

    2015-01-01

    Recently, the world’s first room-temperature maser was demonstrated. The maser consisted of a sapphire ring housing a crystal of pentacene-doped p-terphenyl, pumped by a pulsed rhodamine-dye laser. Stimulated emission of microwaves was aided by the high quality factor and small magnetic mode volume of the maser cavity yet the peak optical pumping power was 1.4 kW. Here we report dramatic miniaturization and 2 orders of magnitude reduction in optical pumping power for a room-temperature maser by coupling a strontium titanate resonator with the spin-polarized population inversion provided by triplet states in an optically excited pentacene-doped p-terphenyl crystal. We observe maser emission in a thimble-sized resonator using a xenon flash lamp as an optical pump source with peak optical power of 70 W. This is a significant step towards the goal of continuous maser operation. PMID:25698634

  11. Electron spin coherence near room temperature in magnetic quantum dots

    PubMed Central

    Moro, Fabrizio; Turyanska, Lyudmila; Wilman, James; Fielding, Alistair J.; Fay, Michael W.; Granwehr, Josef; Patanè, Amalia

    2015-01-01

    We report on an example of confined magnetic ions with long spin coherence near room temperature. This was achieved by confining single Mn2+ spins in colloidal semiconductor quantum dots (QDs) and by dispersing the QDs in a proton-spin free matrix. The controlled suppression of Mn–Mn interactions and minimization of Mn–nuclear spin dipolar interactions result in unprecedentedly long phase memory (TM ~ 8 μs) and spin–lattice relaxation (T1 ~ 10 ms) time constants for Mn2+ ions at T = 4.5 K, and in electron spin coherence observable near room temperature (TM ~ 1 μs). PMID:26040432

  12. Room Temperature Creep Of SiC/SiC Composites

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Gyekenyesi, Andrew; Levine, Stanley (Technical Monitor)

    2001-01-01

    During a recent experimental study, time dependent deformation was observed for a damaged Hi-Nicalon reinforced, BN interphase, chemically vapor infiltrated SiC matrix composites subjected to static loading at room temperature. The static load curves resembled primary creep curves. In addition, acoustic emission was monitored during the test and significant AE activity was recorded while maintaining a constant load, which suggested matrix cracking or interfacial sliding. For similar composites with carbon interphases, little or no time dependent deformation was observed. Evidently, exposure of the BN interphase to the ambient environment resulted in a reduction in the interfacial mechanical properties, i.e. interfacial shear strength and/or debond energy. These results were in qualitative agreement with observations made by Eldridge of a reduction in interfacial shear stress with time at room temperature as measured by fiber push-in experiments.

  13. Synthesis of full-density nanocrystalline tungsten carbide by reduction of tungstic oxide at room temperature

    SciTech Connect

    El-Eskandarany, M.S.; Omori, M.; Ishikuro, M.; Konno, T.J.; Takada, K.; Sumiyama, K.; Hirai, T.; Suzuki, K.

    1996-12-01

    Among the hard alloys, WC alloys find wide industrial applications as tips for cutting tools and wear-resistant parts. Their intrinsic resistance to oxidation and corrosion at high temperatures also makes them desirable as a protective coating for devices at elevated temperatures. In the industrial scale of production, WC is prepared by a direct union of the elements at a temperature of 3,273 to 3,473 K. Accordingly, the high cost of preparation is a disadvantage of this process. Here, the authors report a novel technique for preparing a large amount of WC powder using a simple method. This process is based on mechanical solid-state reduction (MSSR) followed y solid-state reaction (SSR) during room-temperature ball milling (a high energy ball mill, Fritsch P6, was used at a rotation speed of 4.2 s{sup {minus}1}) of a mixture of WO{sub 3}, Mg, and C powders.

  14. Room-temperature Formation of Hollow Cu2O Nanoparticles

    SciTech Connect

    Hung, Ling-I; Tsung, Chia-Kuang; Huang, Wenyu; Yang, Peidong

    2010-01-18

    Monodisperse Cu and Cu2O nanoparticles (NPs) are synthesized using tetradecylphosphonic acid as a capping agent. Dispersing the NPs in chloroform and hexane at room temperature results in the formation of hollow Cu2O NPs and Cu@Cu2O core/shell NPs, respectively. The monodisperse Cu2O NPs are used to fabricate hybrid solar cells with efficiency of 0.14percent under AM 1.5 and 1 Sun illumination.

  15. Spontaneous Polarization Buildup in a Room-Temperature Polariton Laser

    SciTech Connect

    Baumberg, J. J.; Christopoulos, S.; Kavokin, A. V.; Grundy, A. J. D.; Baldassarri Hoeger von Hoegersthal, G.; Butte, R.; Christmann, G.; Feltin, E.; Carlin, J.-F.; Grandjean, N.; Solnyshkov, D. D.; Malpuech, G.

    2008-09-26

    We observe the buildup of strong ({approx}50%) spontaneous vector polarization in emission from a GaN-based polariton laser excited by short optical pulses at room temperature. The Stokes vector of emitted light changes its orientation randomly from one excitation pulse to another, so that the time-integrated polarization remains zero. This behavior is completely different from any previous laser. We interpret this observation in terms of the spontaneous symmetry breaking in a Bose-Einstein condensate of exciton polaritons.

  16. Room-temperature direct alkynylation of arenes with copper acetylides.

    PubMed

    Theunissen, Cédric; Evano, Gwilherm

    2014-09-01

    C-H bond in azoles and polyhalogenated arenes can be smoothly activated by copper acetylides to give the corresponding alkynylated (hetero)arenes by simple reaction at room temperature in the presence of phenanthroline and lithium tert-butoxide under an oxygen atmosphere. These stable, unreactive, and readily available polymers act as especially efficient and practical reagents for the introduction of an alkyne group to a wide number of arenes under remarkably mild conditions. PMID:25115357

  17. Room Temperature Hydrosilylation of Silicon Nanocrystals with Bifunctional Terminal Alkenes

    PubMed Central

    Yu, Yixuan; Hessel, Colin M.; Bogart, Timothy; Panthani, Matthew G.; Rasch, Michael R.; Korgel, Brian A.

    2013-01-01

    H-terminated Si nanocrystals undergo room temperature hydrosilylation with bifunctional alkenes with distal polar moieties—ethyl-, methyl-ester or carboxylic acids—without the aid of light or added catalyst. The passivated Si nanocrystals exhibit bright photoluminescence (PL) and disperse in polar solvents, including water. We propose a reaction mechanism in which ester or carboxylic acid groups facilitate direct nucleophilic attack of the highly curved Si surface of the nanocrystals by the alkene. PMID:23312033

  18. Mercuric iodine room temperature gamma-ray detectors

    NASA Technical Reports Server (NTRS)

    Patt, Bradley E.; Markakis, Jeffrey M.; Gerrish, Vernon M.; Haymes, Robert C.; Trombka, Jacob I.

    1990-01-01

    high resolution mercuric iodide room temperature gamma-ray detectors have excellent potential as an essential component of space instruments to be used for high energy astrophysics. Mercuric iodide detectors are being developed both as photodetectors used in combination with scintillation crystals to detect gamma-rays, and as direct gamma-ray detectors. These detectors are highly radiation damage resistant. The list of applications includes gamma-ray burst detection, gamma-ray line astronomy, solar flare studies, and elemental analysis.

  19. Nonlinear nanochannels for room temperature terahertz heterodyne detection

    NASA Astrophysics Data System (ADS)

    Torres, Jeremie; Nouvel, Philippe; Penot, Alexandre; Varani, Luca; Sangaré, Paul; Grimbert, Bertrand; Faucher, Marc; Ducournau, Guillaume; Gaquière, Christophe; Iñiguez-de-la-Torre, Ignacio; Mateos, Javier; Gonzalez, Tomas

    2013-12-01

    The potentialities of AlGaN/GaN nanochannels with broken symmetry (also called self-switching diodes) as direct and heterodyne THz detectors are analyzed. The operation of the devices in the free space heterodyne detection scheme have been measured at room temperature with RF up to 0.32 THz and explained as a result of high-frequency nonlinearities using Monte Carlo simulations. Intermediate-frequency bandwidth of 40 GHz is obtained.

  20. Observation of Room Temperature Ferromagnetism in InN Nanostructures.

    PubMed

    Roul, Basanta; Kumar, Mahesh; Bhat, Thirumaleshwara N; Rajpalke, Mohana K; Krupanidhi, S B; Kumar, Nitesh; Sundaresan, A

    2015-06-01

    The room temperature ferromagnetic behavior of InN nanostructures grown by molecular beam epitaxy (MBE) is explored by means of magnetization measurements. The saturation magnetization and remanent magnetization are found to be strongly dependent on the size of the nanostructures. This suggests that the ferromagnetism is essentially confined to the surface of the nanostructures due to the possible defects. Raman spectroscopy shows the existence of indium vacancies which could be the source of ferromagnetic ordering in InN nanostructures. PMID:26369060

  1. Method for stabilizing low-level mixed wastes at room temperature

    DOEpatents

    Wagh, A.S.; Singh, D.

    1997-07-08

    A method to stabilize solid and liquid waste at room temperature is provided comprising combining solid waste with a starter oxide to obtain a powder, contacting the powder with an acid solution to create a slurry, said acid solution containing the liquid waste, shaping the now-mixed slurry into a predetermined form, and allowing the now-formed slurry to set. The invention also provides for a method to encapsulate and stabilize waste containing cesium comprising combining the waste with Zr(OH){sub 4} to create a solid-phase mixture, mixing phosphoric acid with the solid-phase mixture to create a slurry, subjecting the slurry to pressure; and allowing the now pressurized slurry to set. Lastly, the invention provides for a method to stabilize liquid waste, comprising supplying a powder containing magnesium, sodium and phosphate in predetermined proportions, mixing said powder with the liquid waste, such as tritium, and allowing the resulting slurry to set. 4 figs.

  2. Method for stabilizing low-level mixed wastes at room temperature

    DOEpatents

    Wagh, Arun S.; Singh, Dileep

    1997-01-01

    A method to stabilize solid and liquid waste at room temperature is provided comprising combining solid waste with a starter oxide to obtain a powder, contacting the powder with an acid solution to create a slurry, said acid solution containing the liquid waste, shaping the now-mixed slurry into a predetermined form, and allowing the now-formed slurry to set. The invention also provides for a method to encapsulate and stabilize waste containing cesium comprising combining the waste with Zr(OH).sub.4 to create a solid-phase mixture, mixing phosphoric acid with the solid-phase mixture to create a slurry, subjecting the slurry to pressure; and allowing the now pressurized slurry to set. Lastly, the invention provides for a method to stabilize liquid waste, comprising supplying a powder containing magnesium, sodium and phosphate in predetermined proportions, mixing said powder with the liquid waste, such as tritium, and allowing the resulting slurry to set.

  3. Room temperature d0 ferromagnetism in ZnS nanocrystals

    NASA Astrophysics Data System (ADS)

    Proshchenko, Vitaly; Horoz, Sabit; Tang, Jinke; Dahnovsky, Yuri

    2016-06-01

    Room temperature ferromagnetic semiconductors have a great deal of advantage because of their easy integration into semiconductor devices. ZnS nanocrystals (NCs), bulk, and surfaces exhibit d0 ferromagnetism at room temperature. The experiments reveal that NC ferromagnetism takes place at low and room temperatures only due to Zn vacancies (S vacancies do not contribute). To understand the mechanism of d0 ferromagnetism, we introduce the surface-bulk model of a nanocrystal, which includes both surface and bulk magnetizations. The calculations demonstrate that the surface has the higher than bulk magnetization. We find the mechanism of the ferromagnetism is due to sulfur s- and p-electrons in a tetrahedral crystal field. The bulk magnetic moment increases with Zn vacancy concentration at small concentrations and then goes down at larger concentrations. A surface magnetic moment behaves differently with the concentration. It is always a monotonically rising function. We find that the total NC magnetic moment increases with the size and concentration of Zn vacancies (only low concentrations). We also study the magnetization per unit cell where we find that it decreases for the surface and increases for bulk magnetism with the NC size.

  4. Bonding of glass microfluidic chips at room temperatures.

    PubMed

    Jia, Zhi-Jian; Fang, Qun; Fang, Zhao-Lun

    2004-09-15

    A simple, room-temperature bonding process was developed for the fabrication of glass microfluidic chips. High-quality bonding with high yields (>95%) was achieved without the requirement of clean room facilities, programmed high-temperature furnaces, pressurized water sources, adhesives, or pressurizing weights. The plates to be bonded were sequentially prewashed with acetone, detergent, high-flow-rate (10-20 m/s) tap water, and absolute ethyl alcohol and were soaked in concentrated sulfuric acid for 8-12 h. The plates were again washed in high-flow-rate tap water for 5 min and, finally, with demineralized water. The plates were bonded by bringing the cleaned surfaces into close contact under a continuous flow of demineralized water and air-dried at room temperature for more than 3 h. This bonding process features simple operation, good smoothness of the plate surface, and high bonding yield. The procedures can be readily applied in any routine laboratory. The bonding strength of glass chips thus produced, measured using a shear force testing procedure, was higher than 6 kg/cm(2). The mechanism for the strong bonding strength is presumably related to the formation of a hydrolyzed layer on the plate surfaces after soaking the substrates in acid or water for extended periods. Microfluidic chips bonded by the above procedure were tested in the CE separation of fluorescein isothiocyanate-labeled amino acids. PMID:15362926

  5. Remote control of magnetostriction-based nanocontacts at room temperature.

    PubMed

    Jammalamadaka, S Narayana; Kuntz, Sebastian; Berg, Oliver; Kittler, Wolfram; Kannan, U Mohanan; Chelvane, J Arout; Sürgers, Christoph

    2015-01-01

    The remote control of the electrical conductance through nanosized junctions at room temperature will play an important role in future nano-electromechanical systems and electronic devices. This can be achieved by exploiting the magnetostriction effects of ferromagnetic materials. Here we report on the electrical conductance of magnetic nanocontacts obtained from wires of the giant magnetostrictive compound Tb0.3Dy0.7Fe1.95 as an active element in a mechanically controlled break-junction device. The nanocontacts are reproducibly switched at room temperature between "open" (zero conductance) and "closed" (nonzero conductance) states by variation of a magnetic field applied perpendicularly to the long wire axis. Conductance measurements in a magnetic field oriented parallel to the long wire axis exhibit a different behaviour where the conductance switches between both states only in a limited field range close to the coercive field. Investigating the conductance in the regime of electron tunneling by mechanical or magnetostrictive control of the electrode separation enables an estimation of the magnetostriction. The present results pave the way to utilize the material in devices based on nano-electromechanical systems operating at room temperature. PMID:26323326

  6. Remote control of magnetostriction-based nanocontacts at room temperature

    NASA Astrophysics Data System (ADS)

    Jammalamadaka, S. Narayana; Kuntz, Sebastian; Berg, Oliver; Kittler, Wolfram; Kannan, U. Mohanan; Chelvane, J. Arout; Sürgers, Christoph

    2015-09-01

    The remote control of the electrical conductance through nanosized junctions at room temperature will play an important role in future nano-electromechanical systems and electronic devices. This can be achieved by exploiting the magnetostriction effects of ferromagnetic materials. Here we report on the electrical conductance of magnetic nanocontacts obtained from wires of the giant magnetostrictive compound Tb0.3Dy0.7Fe1.95 as an active element in a mechanically controlled break-junction device. The nanocontacts are reproducibly switched at room temperature between “open” (zero conductance) and “closed” (nonzero conductance) states by variation of a magnetic field applied perpendicularly to the long wire axis. Conductance measurements in a magnetic field oriented parallel to the long wire axis exhibit a different behaviour where the conductance switches between both states only in a limited field range close to the coercive field. Investigating the conductance in the regime of electron tunneling by mechanical or magnetostrictive control of the electrode separation enables an estimation of the magnetostriction. The present results pave the way to utilize the material in devices based on nano-electromechanical systems operating at room temperature.

  7. Remote control of magnetostriction-based nanocontacts at room temperature

    PubMed Central

    Jammalamadaka, S. Narayana; Kuntz, Sebastian; Berg, Oliver; Kittler, Wolfram; Kannan, U. Mohanan; Chelvane, J. Arout; Sürgers, Christoph

    2015-01-01

    The remote control of the electrical conductance through nanosized junctions at room temperature will play an important role in future nano-electromechanical systems and electronic devices. This can be achieved by exploiting the magnetostriction effects of ferromagnetic materials. Here we report on the electrical conductance of magnetic nanocontacts obtained from wires of the giant magnetostrictive compound Tb0.3Dy0.7Fe1.95 as an active element in a mechanically controlled break-junction device. The nanocontacts are reproducibly switched at room temperature between “open” (zero conductance) and “closed” (nonzero conductance) states by variation of a magnetic field applied perpendicularly to the long wire axis. Conductance measurements in a magnetic field oriented parallel to the long wire axis exhibit a different behaviour where the conductance switches between both states only in a limited field range close to the coercive field. Investigating the conductance in the regime of electron tunneling by mechanical or magnetostrictive control of the electrode separation enables an estimation of the magnetostriction. The present results pave the way to utilize the material in devices based on nano-electromechanical systems operating at room temperature. PMID:26323326

  8. Electrical creation of spin polarization in silicon at room temperature

    NASA Astrophysics Data System (ADS)

    Jansen, Ron

    2010-03-01

    The integration of magnetism and mainstream semiconductor electronics could impact information technology in ways beyond imagination. A pivotal step is the implementation of spin-based electronic functionality in silicon devices. Much of the interest in silicon derives from its prevalence in semiconductor technology and from the robustness and longevity of spin as it is only weakly coupled to other degrees of freedom in the material. Recently it has become possible to induce and detect spin polarization in otherwise non-magnetic semiconductors (GaAs and Si) using all-electrical structures, but so far at temperatures below 150 K and only in n-type material. The main challenges are: (i) to design fully electrical silicon-based spintronic devices with large spin signals, (ii) to demonstrate device operation at room temperature, (iii) to do so for n-type and p-type material, and (iv) to find ways to manipulate spins and spin flow with a gate electric field. After a brief overview of the state of affairs, our recent advances in these areas are described. In particular, we demonstrate room-temperature electrical injection of spin polarization into n-type and p-type silicon from a ferromagnetic tunnel contact, spin manipulation using the Hanle effect, and the electrical detection of the induced spin accumulation. It is shown that a spin splitting as large as 2.9 meV can be created in Si at room temperature, corresponding to an electron spin polarization of 4.6%. The results open the way to the implementation of spin functionality in complementary silicon devices and electronic circuits operating at ambient temperature, and to the exploration of their prospects as well as the fundamental rules that govern their behavior. [4pt] [1] S.P. Dash, S. Sharma, R.S. Patel, M.P. de Jong and R. Jansen, Nature 462, 491 (2009).

  9. Water dimer rotationally resolved millimeter-wave spectrum observation at room temperature.

    PubMed

    Tretyakov, M Yu; Serov, E A; Koshelev, M A; Parshin, V V; Krupnov, A F

    2013-03-01

    Water dimers (H(2)O)(2) are believed to affect Earth's radiation balance and climate, homogeneous condensation, and atmospheric chemistry. Moreover, the pairwise interaction which binds the dimer appears to be of paramount importance for expounding a complete molecular description of the liquid and solid phases of water. However, there have been no secure, direct observations of water dimers at environmentally relevant temperatures despite decades of studies. We report the first unambiguous observation of the dimer spectrum recorded in equilibrium water vapor at room temperature. PMID:23496706

  10. Room-temperature resonant quantum tunneling transport of macroscopic systems.

    PubMed

    Xiong, Zhengwei; Wang, Xuemin; Yan, Dawei; Wu, Weidong; Peng, Liping; Li, Weihua; Zhao, Yan; Wang, Xinmin; An, Xinyou; Xiao, Tingting; Zhan, Zhiqiang; Wang, Zhuo; Chen, Xiangrong

    2014-11-21

    A self-assembled quantum dots array (QDA) is a low dimensional electron system applied to various quantum devices. This QDA, if embedded in a single crystal matrix, could be advantageous for quantum information science and technology. However, the quantum tunneling effect has been difficult to observe around room temperature thus far, because it occurs in a microcosmic and low temperature condition. Herein, we show a designed a quasi-periodic Ni QDA embedded in a single crystal BaTiO3 matrix and demonstrate novel quantum resonant tunneling transport properties around room-temperature according to theoretical calculation and experiments. The quantum tunneling process could be effectively modulated by changing the Ni QDA concentration. The major reason was that an applied weak electric field (∼10(2) V cm(-1)) could be enhanced by three orders of magnitude (∼10(5) V cm(-1)) between the Ni QDA because of the higher permittivity of BaTiO3 and the 'hot spots' of the Ni QDA. Compared with the pure BaTiO3 films, the samples with embedded Ni QDA displayed a stepped conductivity and temperature (σ-T curves) construction. PMID:25307500

  11. Electric-field control of magnetic order above room temperature.

    PubMed

    Cherifi, R O; Ivanovskaya, V; Phillips, L C; Zobelli, A; Infante, I C; Jacquet, E; Garcia, V; Fusil, S; Briddon, P R; Guiblin, N; Mougin, A; Ünal, A A; Kronast, F; Valencia, S; Dkhil, B; Barthélémy, A; Bibes, M

    2014-04-01

    Controlling magnetism by means of electric fields is a key issue for the future development of low-power spintronics. Progress has been made in the electrical control of magnetic anisotropy, domain structure, spin polarization or critical temperatures. However, the ability to turn on and off robust ferromagnetism at room temperature and above has remained elusive. Here we use ferroelectricity in BaTiO3 crystals to tune the sharp metamagnetic transition temperature of epitaxially grown FeRh films and electrically drive a transition between antiferromagnetic and ferromagnetic order with only a few volts, just above room temperature. The detailed analysis of the data in the light of first-principles calculations indicate that the phenomenon is mediated by both strain and field effects from the BaTiO3. Our results correspond to a magnetoelectric coupling larger than previous reports by at least one order of magnitude and open new perspectives for the use of ferroelectrics in magnetic storage and spintronics. PMID:24464245

  12. Electric-field control of magnetic order above room temperature

    NASA Astrophysics Data System (ADS)

    Cherifi, R. O.; Ivanovskaya, V.; Phillips, L. C.; Zobelli, A.; Infante, I. C.; Jacquet, E.; Garcia, V.; Fusil, S.; Briddon, P. R.; Guiblin, N.; Mougin, A.; Ünal, A. A.; Kronast, F.; Valencia, S.; Dkhil, B.; Barthélémy, A.; Bibes, M.

    2014-04-01

    Controlling magnetism by means of electric fields is a key issue for the future development of low-power spintronics. Progress has been made in the electrical control of magnetic anisotropy, domain structure, spin polarization or critical temperatures. However, the ability to turn on and off robust ferromagnetism at room temperature and above has remained elusive. Here we use ferroelectricity in BaTiO3 crystals to tune the sharp metamagnetic transition temperature of epitaxially grown FeRh films and electrically drive a transition between antiferromagnetic and ferromagnetic order with only a few volts, just above room temperature. The detailed analysis of the data in the light of first-principles calculations indicate that the phenomenon is mediated by both strain and field effects from the BaTiO3. Our results correspond to a magnetoelectric coupling larger than previous reports by at least one order of magnitude and open new perspectives for the use of ferroelectrics in magnetic storage and spintronics.

  13. Room-temperature spin thermoelectrics in metallic films

    NASA Astrophysics Data System (ADS)

    Tölle, Sebastian; Gorini, Cosimo; Eckern, Ulrich

    2014-12-01

    Considering metallic films at room temperature, we present the first theoretical study of the spin Nernst and thermal Edelstein effects that takes into account dynamical spin-orbit coupling, i.e., direct spin-orbit coupling with the vibrating lattice (phonons) and impurities. This gives rise to a novel process, namely, a dynamical side-jump mechanism, and to dynamical Elliott-Yafet spin relaxation, never before considered in this context. Both are the high-temperature counterparts of the well-known T =0 side-jump and Elliott-Yafet, central to the current understanding of the spin Hall, spin Nernst and Edelstein (current-induced spin polarization) effects at low T . We consider the experimentally relevant regime T >TD , with TD the Debye temperature, as the latter is lower than room temperature in transition metals such as Pt, Au and Ta typically employed in spin injection/extraction experiments. We show that the interplay between intrinsic (Bychkov-Rashba type) and extrinsic (dynamical) spin-orbit coupling yields a nonlinear T dependence of the spin Nernst and spin Hall conductivities.

  14. Terahertz absorption spectrum of para and ortho water vapors at different humidities at room temperature

    NASA Astrophysics Data System (ADS)

    Xin, X.; Altan, H.; Saint, A.; Matten, D.; Alfano, R. R.

    2006-11-01

    Terahertz time-domain spectroscopy has been used to measure the absorption of water vapor in 0.2-2.4THz range from low to high humidity at room temperature. The observed absorption lines are due to the water molecular rotations in the ground vibrational state. We find that the absorption strength of para transitions increases as humidity increases, while the absorption strength of ortho transitions increases and then decreases in intensity with increasing humidity. We explain this difference based on the nuclear spin statistics based ratio of ortho to para water monomer populations at room temperature. The preferential adsorption on the solid surfaces of para water leads to an ortho dominated vapor cloud whose monomer rotational absorption intensity decreases due to the effects of dimerization, molecular collisions, clustering, and interactions with liquid droplets at high concentrations.

  15. Electroluminescence from localized defects in zinc oxide: toward electrically driven single photon sources at room temperature.

    PubMed

    Choi, Sumin; Berhane, Amanuel M; Gentle, Angus; Ton-That, Cuong; Phillips, Matthew R; Aharonovich, Igor

    2015-03-18

    Single photon sources are required for a wide range of applications in quantum information science, quantum cryptography, and quantum communications. However, the majority of room temperature emitters to date are only excited optically, which limits their proper integration into scalable devices. In this work, we overcome this limitation and present room temperature electrically driven light emission from localized defects in zinc oxide (ZnO) nanoparticles and thin films. The devices emit in the red spectral range and show excellent rectifying behavior. The emission is stable over an extensive period of time, providing an important prerequisite for practical devices. Our results open possibilities for building new ZnO-based quantum integrated devices that incorporate solid-state single photon sources for quantum information technologies. PMID:25741632

  16. Room-temperature antiferromagnetism in CuMnAs

    NASA Astrophysics Data System (ADS)

    Máca, F.; Mašek, J.; Stelmakhovych, O.; Martí, X.; Reichlová, H.; Uhlířová, K.; Beran, P.; Wadley, P.; Novák, V.; Jungwirth, T.

    2012-04-01

    We report on an experimental and theoretical study of CuMn-V compounds. In agreement with previous works we find low-temperature antiferromagnetism with Néel temperature of 50 K in the cubic half-Heusler CuMnSb. We demonstrate that the orthorhombic CuMnAs is a room-temperature antiferromagnet. Our results are based on X-ray diffraction, magnetization, transport, and differential thermal analysis measurements, and on density-functional theory calculations of the magnetic structure of CuMn-V compounds. In the discussion part of the paper we make a prediction, based on our density-functional theory calculations, that the electronic structure of CuMn-V compounds makes a transition from a semimetal to a semiconductor upon introducing the lighter group-V elements.

  17. Terahertz pulsed photogenerated current in microdiodes at room temperature

    SciTech Connect

    Ilkov, Marjan; Torfason, Kristinn; Manolescu, Andrei Valfells, Ágúst

    2015-11-16

    Space-charge modulation of the current in a vacuum diode under photoemission leads to the formation of beamlets with time periodicity corresponding to THz frequencies. We investigate the effect of the emitter temperature and internal space-charge forces on the formation and persistence of the beamlets. We find that temperature effects are most important for beam degradation at low values of the applied electric field, whereas at higher fields, intra-beamlet space-charge forces are dominant. The current modulation is most robust when there is only one beamlet present in the diode gap at a time, corresponding to a macroscopic version of the Coulomb blockade. It is shown that a vacuum microdiode can operate quite well as a tunable THz oscillator at room temperature with an applied electric field above 10 MV/m and a diode gap of the order of 100 nm.

  18. Does the electric power grid need a room temperature superconductor?

    NASA Astrophysics Data System (ADS)

    Malozemoff, A. P.

    2013-11-01

    Superconductivity can revolutionize electric power grids, for example with high power underground cables to open urban power bottlenecks and fault current limiters to solve growing fault currents problems. Technology based on high temperature superconductor (HTS) wire is beginning to meet these critical needs. Wire performance is continually improving. For example, American Superconductor has recently demonstrated long wires with up to 500 A/cm-width at 77 K, almost doubling its previous production performance. But refrigeration, even at 77 K, is a complication, driving interest in discovering room temperature superconductors (RTS). Unfortunately, short coherence lengths and accelerated flux creep will make RTS applications unlikely. Existing HTS technology, in fact, offers a good compromise of relatively high operating temperature but not so high as to incur coherence-length and flux-creep limitations. So - no, power grids do not need RTS; existing HTS wire is proving to be what grids really need.

  19. Iron bulk lasers working under cryogenic and room temperature

    NASA Astrophysics Data System (ADS)

    Jelínková, H.; Doroshenko, M. E.; Šulc, J.; Jelínek, M.; Nemec, M.; Zagoruiko, Y. A.; Kovalenko, N. O.; Gerasimenko, A. S.; Puzikov, V. M.; Komar, V. K.

    2014-12-01

    Temperature dependence of spectroscopic characteristics as well as laser properties of the bulk Bridgman-grown Fe:ZnSe and Fe,Cr:Zn1-xMgxSe (x = 0.19, 0.38) active media were investigated under room and various cryogenic - liquid nitrogen - temperature . The pumping was provided by Er:YAG laser radiation at the wavelength of 2.94 μm, with energy 15 mJ in 110 ns Q-switched pulse or 200 mJ in 220 μs free-running pulse. The 55 mm long hemispherical resonator was formed by a dichroic pumping mirror (T = 92 % @ 2.94 μm and R = 100% @ 4.5 μm) and a concave output coupler (R = 95 % @ 4.5 μm, r = 200 mm). A strong dependence of generated output radiation parameters on temperature was observed for all samples.

  20. Room temperature GaAsSb single nanowire infrared photodetectors

    NASA Astrophysics Data System (ADS)

    Li, Ziyuan; Yuan, Xiaoming; Fu, Lan; Peng, Kun; Wang, Fan; Fu, Xiao; Caroff, Philippe; White, Thomas P.; Tan, Hark Hoe; Jagadish, Chennupati

    2015-11-01

    Antimonide-based ternary III-V nanowires (NWs) allow for a tunable bandgap over a wide range, which is highly interesting for optoelectronics applications, and in particular for infrared photodetection. Here we demonstrate room temperature operation of GaAs0.56Sb0.44 NW infrared photodetectors grown by metal organic vapor phase epitaxy. These GaAs0.56Sb0.44 NWs have uniform axial composition and show p-type conductivity with a peak field-effect mobility of ˜12 cm2 V-1 s-1). Under light illumination, single GaAs0.56Sb0.44 NW photodetectors exhibited typical photoconductor behavior with an increased photocurrent observed with the increase of temperature owing to thermal activation of carrier trap states. A broadband infrared photoresponse with a long wavelength cutoff at ˜1.66 μm was obtained at room temperature. At a low operating bias voltage of 0.15 V a responsivity of 2.37 (1.44) A/W with corresponding detectivity of 1.08 × 109 (6.55 × 108) {{cm}}\\sqrt{{{Hz}}}/{{W}} were achieved at the wavelength of 1.3 (1.55) μm, indicating that ternary GaAs0.56Sb0.44 NWs are promising photodetector candidates for small footprint integrated optical telecommunication systems.

  1. Non-diffusive thermal conductivity in semiconductors at room temperature

    NASA Astrophysics Data System (ADS)

    Maznev, Alexei; Johnson, Jeremy; Eliason, Jeffrey; Nelson, Keith; Minnich, Austin; Collins, Kimberlee; Chen, Gang; Cuffe, John; Kehoe, Timothy; Sotomayor Torres, Clivia

    2012-02-01

    The ``textbook'' value of phonon mean free path (MFP) in silicon at room temperature is ˜40 nm. However, a large contribution to thermal conductivity comes from low-frequency phonons with much longer MFPs. We find that heat transport in semiconductors such as Si and GaAs significantly deviates from the Fourier law at distances much longer than previously thought, >=1 μm at room temperature and above. We use the laser-induced transient thermal grating technique in which absorption of crossed laser pulses in a sample sets up a sinusoidal temperature profile monitored via diffraction of a probe laser beam. By changing the period of the thermal grating we vary the thermal transport distance within the range ˜1-10 μm. In measurements performed on thin free-standing Si membranes and on bulk GaAs the thermal grating decay time deviates from the expected quadratic dependence on the grating period, thus providing model-independent evidence of non-diffusive transport. The simplicity of the experimental configuration permits analytical treatment of non-equilibrium phonon transport with the Boltzmann transport equation. Our analysis shows that at small grating periods the effective thermal conductivity is reduced due to diminishing contributions of ``ballistic'' low-frequency phonons with long MFPs.

  2. Superradiance of High Density Frenkel Excitons at Room Temperature

    NASA Astrophysics Data System (ADS)

    Wang, H. Z.; Zheng, X. G.; Zhao, F. L.; Gao, Z. L.; Yu, Z. X.

    1995-05-01

    Superradiance of high density Frenkel excitons in an R-phycoerythrin single crystal is observed at room temperature for the first time. No fluorescence is observed except the emission at the sharp exciton band when the superradiance of excitons occurs, and the higher the pump density, the sharper the emission bandwidth. A redshift and a blueshift are observed at the rise time and the fall time of the emission pulse, respectively. The experimental results also imply deformed-boson properties of high density Frenkel excitons.

  3. Development of bulk GaAs room temperature radiation detectors

    SciTech Connect

    McGregor, D.S.; Knoll, G.F. . Dept. of Nuclear Engineering); Eisen, Y. . Soreq Nuclear Research Center); Brake, R. )

    1992-10-01

    This paper reports on GaAs, a wide band gap semiconductor with potential use as a room temperature radiation detector. Various configurations of Schottky diode detectors were fabricated with bulk crystals of liquid encapsulated Czochralski (LEC) semi-insulating undoped GaAs material. Basic detector construction utilized one Ti/Au Schottky contact and one Au/Ge/Ni alloyed ohmic contact. Pulsed X-ray analysis indicated pulse decay times dependent on bias voltage. Pulse height analysis disclosed non-uniform electric field distributions across the detectors tentatively explained as a consequence of native deep level donors (EL2) in the crystal.

  4. Continued development of room temperature semiconductor nuclear detectors

    NASA Astrophysics Data System (ADS)

    Kim, Hadong; Cirignano, Leonard; Churilov, Alexei; Ciampi, Guido; Kargar, Alireza; Higgins, William; O'Dougherty, Patrick; Kim, Suyoung; Squillante, Michael R.; Shah, Kanai

    2010-08-01

    Thallium bromide (TlBr) and related ternary compounds, TlBrI and TlBrCl, have been under development for room temperature gamma ray spectroscopy due to several promising properties. Due to recent advances in material processing, electron mobility-lifetime product of TlBr is close to Cd(Zn)Te's value which allowed us to fabricate large working detectors. We were also able to fabricate and obtain spectroscopic results from TlBr Capacitive Frisch Grid detector and orthogonal strip detectors. In this paper we report on our recent TlBr and related ternary detector results and preliminary results from Cinnabar (HgS) detectors.

  5. Organic semiconducting single crystals as next generation of low-cost, room-temperature electrical X-ray detectors.

    PubMed

    Fraboni, Beatrice; Ciavatti, Andrea; Merlo, Francesco; Pasquini, Luca; Cavallini, Anna; Quaranta, Alberto; Bonfiglio, Annalisa; Fraleoni-Morgera, Alessandro

    2012-05-01

    Direct, solid-state X-ray detectors based on organic single crystals are shown to operate at room temperature, in air, and at voltages as low as a few volts, delivering a stable and reproducible linear response to increasing X-ray dose rates, with notable radiation hardness and resistance to aging. All-organic and optically transparent devices are reported. PMID:22451192

  6. Effect of nanoscale confinement on freezing of modified water at room temperature and ambient pressure.

    PubMed

    Deshmukh, Sanket; Kamath, Ganesh; Sankaranarayanan, Subramanian K R S

    2014-06-01

    Understanding the phase behavior of confined water is central to fields as diverse as heterogeneous catalysis, corrosion, nanofluidics, and to emerging energy technologies. Altering the state points (temperature, pressure, etc.) or introduction of a foreign surface can result in the phase transformation of water. At room temperature, ice nucleation is a very rare event and extremely high pressures in the GPa-TPa range are required to freeze water. Here, we perform computer experiments to artificially alter the balance between electrostatic and dispersion interactions between water molecules, and demonstrate nucleation and growth of ice at room temperature in a nanoconfined environment. Local perturbations in dispersive and electrostatic interactions near the surface are shown to provide the seed for nucleation (nucleation sites), which lead to room temperature liquid-solid phase transition of confined water. Crystallization of water occurs over several tens of nanometers and is shown to be independent of the nature of the substrate (hydrophilic oxide vs. hydrophobic graphene and crystalline oxide vs. amorphous diamond-like carbon). Our results lead us to hypothesize that the freezing transition of confined water can be controlled by tuning the relative dispersive and electrostatic interaction. PMID:24715572

  7. Anaerobic digestion in mesophilic and room temperature conditions: Digestion performance and soil-borne pathogen survival.

    PubMed

    Chen, Le; Jian, Shanshan; Bi, Jinhua; Li, Yunlong; Chang, Zhizhou; He, Jian; Ye, Xiaomei

    2016-05-01

    Tomato plant waste (TPW) was used as the feedstock of a batch anaerobic reactor to evaluate the effect of anaerobic digestion on Ralstonia solanacearum and Phytophthora capsici survival. Batch experiments were carried out for TS (total solid) concentrations of 2%, 4% and 6% respectively, at mesophilic (37±1°C) and room (20-25°C) temperatures. Results showed that higher digestion performance was achieved under mesophilic digestion temperature and lower TS concentration conditions. The biogas production ranged from 71 to 416L/kg VS (volatile solids). The inactivation of anaerobic digestion tended to increase as digestion performance improved. The maximum log copies reduction of R. solanacearum and P. capsici detected by quantitative PCR (polymerase chain reaction) were 3.80 and 4.08 respectively in reactors with 4% TS concentration at mesophilic temperatures. However, both in mesophilic and room temperature conditions, the lowest reduction of R. solanacearum was found in the reactors with 6% TS concentration, which possessed the highest VFA (volatile fatty acid) concentration. These findings indicated that simple accumulation of VFAs failed to restrain R. solanacearum effectively, although the VFAs were considered poisonous. P. capsici was nearly completely dead under all conditions. Based on the digestion performance and the pathogen survival rate, a model was established to evaluate the digestate biosafety. PMID:27155428

  8. Dynamics and structure of room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Fayer, Michael D.

    2014-11-01

    Room temperature ionic liquids (RTIL) are intrinsically interesting because they simultaneously have properties that are similar to organic liquids and liquid salts. In addition, RTILs are increasingly being considered for and used in technological applications. RTILs are usually composed of an organic cation and an inorganic anion. The organic cation, such as imidazolium, has alkyl chains of various lengths. The disorder in the liquid produced by the presence of the alkyl groups lowers the temperature for crystallization below room temperature and can also result in supercooling and glass formation rather than crystallization. The presence of the alkyl moieties also results in a segregation of the liquid into ionic and organic regions. In this article, experiments are presented that address the relationship between RTIL dynamics and structure. Time resolved fluorescence anisotropy measurements were employed to study the local environments in the organic and ionic regions of RTILs using a nonpolar chromophore that locates in the organic regions and an ionic chromophore that locates in the ionic regions. In the alkyl regions, the in plane and out of plane orientational friction coefficients change in different manners as the alkyl chains get longer. Both friction coefficients converge toward those of a long chain length hydrocarbon as the RTIL chains increase in length, which demonstrates that for sufficiently long alkyl chains the RTIL organic regions have properties similar to a hydrocarbon. However, putting Li+ in the ionic regions changes the friction coefficients in the alkyl regions, which demonstrates that changes of the ion structural organization influences the organization of the alkyl chains. Optical heterodyne detected optical Kerr effect (OHD-OKE) experiments were used to examine the orientational relaxation dynamics of RTILs over times scales of a hundred femtoseconds to a hundred nanoseconds. Detailed temperature dependent studies in the liquid and

  9. Identifying multiexcitons in Mo S2 monolayers at room temperature

    NASA Astrophysics Data System (ADS)

    Lee, Hyun Seok; Kim, Min Su; Kim, Hyun; Lee, Young Hee

    2016-04-01

    One of the unique features of atomically thin two-dimensional materials is strong Coulomb interactions due to the reduced dielectric screening effect; this feature enables the study of many-body phenomena such as excitons, trions, and biexcitons. However, identification of biexcitons remains unresolved owing to their broad peak feature at room temperature. Here, we investigate multiexcitons in monolayer Mo S2 using both electrical and optical doping and identify the transition energies for each exciton. The binding energy of the assigned biexciton is twice that of the trion, in quantitative agreement with theoretical predictions. The biexciton population is predominant under optical doping but negligible under electrical doping. The biexciton population is quadratically proportional to the exciton population, obeying the mass-action theory. Our results illustrate the stable formation of not only trions but also biexcitons due to strong Coulomb interaction even at room temperature; therefore, these results provide a deeper understanding of the complex excitonic behaviors in two-dimensional semiconductors.

  10. Observation of room-temperature skyrmion Hall effect

    NASA Astrophysics Data System (ADS)

    Jiang, W.; Zhang, X.; Upadhyaya, P.; Zhang, W.; Yu, G.; Jungfleisch, M.; Fradin, F.; Pearson, J.; Tserkovnyak, Y.; Wang, K.; Heinonen, O.; Zhou, Y.; Te Velthuis, Suzanne; Hoffmann, A.

    The realization of room-temperature magnetic skyrmions is key to enabling the implementation of skyrmion-based spintronics. In this work, we present the efficient conversion of chiral stripe domains into Néel skyrmions through a geometrical constriction patterned in a Ta/CoFeB/TaOx trilayer film at room temperature. This is enabled by an interfacial Dzyaloshinskii-Moriya interaction, and laterally divergent current-induced spin-orbit torques. We further show the generation of magnetic skyrmions solely by the divergent spin-orbit torques through a nonmagnetic point contact. By increasing the current density, we observe the skyrmion Hall effect - that is the accumulation of skyrmions at one side of the device. The related Hall angle for skyrmion motion is also revealed under an ac driving current. Financial support for the work at Argonne came from Department of Energy, Office of Science, Basic Energy Science, Materials Sciences and Engineering Division, work at UCLA was supported by TANMS.

  11. Simple room temperature bonding of thermoplastics and poly(dimethylsiloxane).

    PubMed

    Sunkara, Vijaya; Park, Dong-Kyu; Hwang, Hyundoo; Chantiwas, Rattikan; Soper, Steven A; Cho, Yoon-Kyoung

    2011-03-01

    We describe a simple and versatile method for bonding thermoplastics to elastomeric polydimethylsiloxane (PDMS) at room temperature. The bonding of various thermoplastics including polycarbonate (PC), cyclic olefin copolymer (COC), polymethylmethacrylate (PMMA), and polystyrene (PS), to PDMS has been demonstrated at room temperature. An irreversible bonding was formed instantaneously when the thermoplastics, activated by oxygen plasma followed by aminopropyltriethoxysilane modification, were brought into contact with the plasma treated PDMS. The surface modified thermoplastics were characterized by water contact angle measurements and X-ray photoelectron spectroscopy. The tensile strength of the bonded hybrid devices fabricated with PC, COC, PMMA, and PS was found to be 430, 432, 385, and 388 kPa, respectively. The assembled devices showed high burst resistance at a maximum channel pressure achievable by an in-house built syringe pump, 528 kPa. Furthermore, they displayed very high hydrolytic stability; no significant change was observed even after the storage in water at 37 °C over a period of three weeks. In addition, this thermoplastic-to-PDMS bonding technique has been successfully employed to fabricate a relatively large sized device. For example, a lab-on-a-disc with a diameter of 12 cm showed no leakage when it spins for centrifugal fluidic pumping at a very high rotating speed of 6000 rpm. PMID:21152492

  12. Exfoliated black phosphorus gas sensing properties at room temperature

    NASA Astrophysics Data System (ADS)

    Donarelli, M.; Ottaviano, L.; Giancaterini, L.; Fioravanti, G.; Perrozzi, F.; Cantalini, C.

    2016-06-01

    Room temperature gas sensing properties of chemically exfoliated black phosphorus (BP) to oxidizing (NO2, CO2) and reducing (NH3, H2, CO) gases in a dry air carrier have been reported. To study the gas sensing properties of BP, chemically exfoliated BP flakes have been drop casted on Si3N4 substrates provided with Pt comb-type interdigitated electrodes in N2 atmosphere. Scanning electron microscopy and x-ray photoelectron spectroscopy characterizations show respectively the occurrence of a mixed structure, composed of BP coarse aggregates dispersed on BP exfoliated few layer flakes bridging the electrodes, and a clear 2p doublet belonging to BP, which excludes the occurrence of surface oxidation. Room temperature electrical tests in dry air show a p-type response of multilayer BP with measured detection limits of 20 ppb and 10 ppm to NO2 and NH3 respectively. No response to CO and CO2 has been detected, while a slight but steady sensitivity to H2 has been recorded. The reported results confirm, on an experimental basis, what was previously theoretically predicted, demonstrating the promising sensing properties of exfoliated BP.

  13. Low-field magnetoelectric effect at room temperature

    NASA Astrophysics Data System (ADS)

    Kitagawa, Yutaro; Hiraoka, Yuji; Honda, Takashi; Ishikura, Taishi; Nakamura, Hiroyuki; Kimura, Tsuyoshi

    2010-10-01

    The discoveries of gigantic ferroelectric polarization in BiFeO3 (ref. 1) and ferroelectricity accompanied by a magnetic order in TbMnO3 (ref. 2) have renewed interest in research on magnetoelectric multiferroics, materials in which magnetic and ferroelectric orders coexist, from both fundamental and technological points of view. Among several different types of magnetoelectric multiferroic, magnetically induced ferroelectrics in which ferroelectricity is induced by complex magnetic orders, such as spiral orders, exhibit giant magnetoelectric effects, remarkable changes in electric polarization in response to a magnetic field. Many magnetically induced ferroelectrics showing the magnetoelectric effects have been found in the past several years. From a practical point of view, however, their magnetoelectric effects are useless because they operate only far below room temperature (for example, 28K in TbMnO3 (ref. 2) and 230K in CuO (ref. 11)). Furthermore, in most of them, the operating magnetic field is an order of tesla that is too high for practical applications. Here we report materials, Z-type hexaferrites, overcoming these problems on magnetically induced ferroelectrics. The best magnetoelectric properties were obtained for Sr3Co2Fe24O41 ceramics sintered in oxygen, which exhibit a low-field magnetoelectric effect at room temperature. Our result represents an important step towards practical device applications using the magnetoelectric effects.

  14. Linear magnetoelectricity at room temperature in perovskite superlattices by design

    NASA Astrophysics Data System (ADS)

    Ghosh, Saurabh; Das, Hena; Fennie, Craig J.

    2015-11-01

    Discovering materials that display a linear magnetoelectric (ME) effect at room temperature is a challenge. Such materials could facilitate devices based on the electric field control of magnetism. Here we present simple, chemically intuitive design rules to identify a class of bulk magnetoelectric materials based on the "bicolor" layering of P b n m ferrite perovskites, e.g., LaFeO3/LnFeO3 superlattices, Ln = lanthanide cation. We use first-principles density functional theory calculations to confirm these ideas. We elucidate the origin of this effect and show it is a general consequence of the layering of any bicolor P b n m perovskite superlattice in which the number of constituent layers are odd (leading to a form of hybrid improper ferroelectricity). Our calculations suggest that the ME effect in these superlattices is larger than that observed in the prototypical magnetoelectric materials Cr2O3 and BiFeO3. Furthermore, in these proposed materials, the strength of the linear ME coupling increases with the magnitude of the induced spontaneous polarization which is controlled by the La/Ln cation radius mismatch. We use a simple mean field model to show that the proposed materials order magnetically above room temperature.

  15. Primary standard of optical power operating at room temperature

    NASA Astrophysics Data System (ADS)

    Dönsberg, Timo; Sildoja, Meelis; Manoocheri, Farshid; Merimaa, Mikko; Petroff, Leo; Ikonen, Erkki

    2014-08-01

    The Predictable Quantum Efficient Detector (PQED) is evaluated as a new primary standard of optical power. Design and characterization results are presented for a new compact room temperature PQED that consists of two custom-made induced junction photodiodes mounted in a wedged trap configuration. The detector assembly includes a window aligned in Brewster angle in front of the photodiodes for high transmission of p polarized light. The detector can also be operated without the window, in which case a dry nitrogen flow system is utilized to prevent dust contamination of the photodiodes. Measurements of individual detectors at the wavelength of 488 nm indicate that reflectance and internal quantum efficiency are consistent within 14 ppm and 10 ppm (ppm = part per million), respectively, and agree with the predicted values. The measured photocurrent ratio of the two photodiodes confirms the predicted value for s and p polarized light, and the spatial variation in the photocurrent ratio can be used to estimate the uniformity in the thickness of the silicon dioxide layer on the surface of the photodiodes. In addition, the spatial non-uniformity of the responsivity of the PQED is an order of magnitude lower than that of single photodiodes. Such data provide evidence that the room temperature PQED may replace the cryogenic radiometer as a primary standard of optical power in the visible wavelength range.

  16. Self-transducing silicon nanowire electromechanical systems at room temperature.

    PubMed

    He, Rongrui; Feng, X L; Roukes, M L; Yang, Peidong

    2008-06-01

    Electronic readout of the motions of genuinely nanoscale mechanical devices at room temperature imposes an important challenge for the integration and application of nanoelectromechanical systems (NEMS). Here, we report the first experiments on piezoresistively transduced very high frequency Si nanowire (SiNW) resonators with on-chip electronic actuation at room temperature. We have demonstrated that, for very thin (~90 nm down to ~30 nm) SiNWs, their time-varying strain can be exploited for self-transducing the devices' resonant motions at frequencies as high as approximately 100 MHz. The strain of wire elongation, which is only second-order in doubly clamped structures, enables efficient displacement transducer because of the enhanced piezoresistance effect in these SiNWs. This intrinsically integrated transducer is uniquely suited for a class of very thin wires and beams where metallization and multilayer complex patterning on devices become impractical. The 30 nm thin SiNW NEMS offer exceptional mass sensitivities in the subzeptogram range. This demonstration makes it promising to advance toward NEMS sensors based on ultrathin and even molecular-scale SiNWs, and their monolithic integration with microelectronics on the same chip. PMID:18481896

  17. Unconditional polarization qubit quantum memory at room temperature

    NASA Astrophysics Data System (ADS)

    Namazi, Mehdi; Kupchak, Connor; Jordaan, Bertus; Shahrokhshahi, Reihaneh; Figueroa, Eden

    2016-05-01

    The creation of global quantum key distribution and quantum communication networks requires multiple operational quantum memories. Achieving a considerable reduction in experimental and cost overhead in these implementations is thus a major challenge. Here we present a polarization qubit quantum memory fully-operational at 330K, an unheard frontier in the development of useful qubit quantum technology. This result is achieved through extensive study of how optical response of cold atomic medium is transformed by the motion of atoms at room temperature leading to an optimal characterization of room temperature quantum light-matter interfaces. Our quantum memory shows an average fidelity of 86.6 +/- 0.6% for optical pulses containing on average 1 photon per pulse, thereby defeating any classical strategy exploiting the non-unitary character of the memory efficiency. Our system significantly decreases the technological overhead required to achieve quantum memory operation and will serve as a building block for scalable and technologically simpler many-memory quantum machines. The work was supported by the US-Navy Office of Naval Research, Grant Number N00141410801 and the Simons Foundation, Grant Number SBF241180. B. J. acknowledges financial assistance of the National Research Foundation (NRF) of South Africa.

  18. New Flexible Channels for Room Temperature Tunneling Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Hao, Boyi; Asthana, Anjana; Hazaveh, Paniz Khanmohammadi; Bergstrom, Paul L.; Banyai, Douglas; Savaikar, Madhusudan A.; Jaszczak, John A.; Yap, Yoke Khin

    2016-02-01

    Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized boron nitride nanotubes (QDs-BNNTs) can be used as the flexible tunneling channels of TFETs at room temperatures. The electrical insulating BNNTs are used as the one-dimensional (1D) substrates to confine the uniform formation of Fe QDs on their surface as the flexible tunneling channel. Consistent semiconductor-like transport behaviors under various bending conditions are detected by scanning tunneling spectroscopy in a transmission electron microscopy system (in-situ STM-TEM). As suggested by computer simulation, the uniform distribution of Fe QDs enable an averaging effect on the possible electron tunneling pathways, which is responsible for the consistent transport properties that are not sensitive to bending.

  19. Room-temperature chiral magnetic skyrmions in ultrathin magnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Boulle, Olivier; Vogel, Jan; Yang, Hongxin; Pizzini, Stefania; de Souza Chaves, Dayane; Locatelli, Andrea; Menteş, Tevfik Onur; Sala, Alessandro; Buda-Prejbeanu, Liliana D.; Klein, Olivier; Belmeguenai, Mohamed; Roussigné, Yves; Stashkevich, Andrey; Chérif, Salim Mourad; Aballe, Lucia; Foerster, Michael; Chshiev, Mairbek; Auffret, Stéphane; Miron, Ioan Mihai; Gaudin, Gilles

    2016-05-01

    Magnetic skyrmions are chiral spin structures with a whirling configuration. Their topological properties, nanometre size and the fact that they can be moved by small current densities have opened a new paradigm for the manipulation of magnetization at the nanoscale. Chiral skyrmion structures have so far been experimentally demonstrated only in bulk materials and in epitaxial ultrathin films, and under an external magnetic field or at low temperature. Here, we report on the observation of stable skyrmions in sputtered ultrathin Pt/Co/MgO nanostructures at room temperature and zero external magnetic field. We use high lateral resolution X-ray magnetic circular dichroism microscopy to image their chiral Néel internal structure, which we explain as due to the large strength of the Dzyaloshinskii–Moriya interaction as revealed by spin wave spectroscopy measurements. Our results are substantiated by micromagnetic simulations and numerical models, which allow the identification of the physical mechanisms governing the size and stability of the skyrmions.

  20. Room temperature quantum coherence in a potential molecular qubit

    NASA Astrophysics Data System (ADS)

    Bader, Katharina; Dengler, Dominik; Lenz, Samuel; Endeward, Burkhard; Jiang, Shang-Da; Neugebauer, Petr; van Slageren, Joris

    2014-10-01

    The successful development of a quantum computer would change the world, and current internet encryption methods would cease to function. However, no working quantum computer that even begins to rival conventional computers has been developed yet, which is due to the lack of suitable quantum bits. A key characteristic of a quantum bit is the coherence time. Transition metal complexes are very promising quantum bits, owing to their facile surface deposition and their chemical tunability. However, reported quantum coherence times have been unimpressive. Here we report very long quantum coherence times for a transition metal complex of 68 μs at low temperature (qubit figure of merit QM=3,400) and 1 μs at room temperature, much higher than previously reported values for such systems. We show that this achievement is because of the rigidity of the lattice as well as removal of nuclear spins from the vicinity of the magnetic ion.

  1. Room temperature skyrmion ground state stabilized through interlayer exchange coupling

    SciTech Connect

    Chen, Gong Schmid, Andreas K.; Mascaraque, Arantzazu; N'Diaye, Alpha T.

    2015-06-15

    Possible magnetic skyrmion device applications motivate the search for structures that extend the stability of skyrmion spin textures to ambient temperature. Here, we demonstrate an experimental approach to stabilize a room temperature skyrmion ground state in chiral magnetic films via exchange coupling across non-magnetic spacer layers. Using spin polarized low-energy electron microscopy to measure all three Cartesian components of the magnetization vector, we image the spin textures in Fe/Ni films. We show how tuning the thickness of a copper spacer layer between chiral Fe/Ni films and perpendicularly magnetized Ni layers permits stabilization of a chiral stripe phase, a skyrmion phase, and a single domain phase. This strategy to stabilize skyrmion ground states can be extended to other magnetic thin film systems and may be useful for designing skyrmion based spintronics devices.

  2. Room temperature quantum coherence in a potential molecular qubit.

    PubMed

    Bader, Katharina; Dengler, Dominik; Lenz, Samuel; Endeward, Burkhard; Jiang, Shang-Da; Neugebauer, Petr; van Slageren, Joris

    2014-01-01

    The successful development of a quantum computer would change the world, and current internet encryption methods would cease to function. However, no working quantum computer that even begins to rival conventional computers has been developed yet, which is due to the lack of suitable quantum bits. A key characteristic of a quantum bit is the coherence time. Transition metal complexes are very promising quantum bits, owing to their facile surface deposition and their chemical tunability. However, reported quantum coherence times have been unimpressive. Here we report very long quantum coherence times for a transition metal complex of 68 μs at low temperature (qubit figure of merit QM=3,400) and 1 μs at room temperature, much higher than previously reported values for such systems. We show that this achievement is because of the rigidity of the lattice as well as removal of nuclear spins from the vicinity of the magnetic ion. PMID:25328006

  3. A Polar Corundum Oxide Displaying Weak Ferromagnetism at Room Temperature

    PubMed Central

    2012-01-01

    Combining long-range magnetic order with polarity in the same structure is a prerequisite for the design of (magnetoelectric) multiferroic materials. There are now several demonstrated strategies to achieve this goal, but retaining magnetic order above room temperature remains a difficult target. Iron oxides in the +3 oxidation state have high magnetic ordering temperatures due to the size of the coupled moments. Here we prepare and characterize ScFeO3 (SFO), which under pressure and in strain-stabilized thin films adopts a polar variant of the corundum structure, one of the archetypal binary oxide structures. Polar corundum ScFeO3 has a weak ferromagnetic ground state below 356 K—this is in contrast to the purely antiferromagnetic ground state adopted by the well-studied ferroelectric BiFeO3. PMID:22280499

  4. Enabling NIR imaging at room temperature using quantum dots

    NASA Astrophysics Data System (ADS)

    Le Calvez, S.; Bourvon, H.; Kanaan, H.; Meunier-Della Gatta, S.; Philippot, C.; Reiss, P.

    2011-10-01

    Imaging in visible light at room temperature is now a well-mastered technology, whereas imaging in the near infrared (NIR) remains a challenge. NIR imaging has many applications like sensing, night vision and biological diagnostics. Unfortunately, silicon detectors are inefficient above 1000 nm, and other IR technologies still need low working temperatures and are thus expensive. Colloidal quantum dots can overcome these limitations thanks to their absorption wavelength tunability depending on their chemical composition and size. After a brief review of this research field, we will present the preparation of hybrid photodetectors using NIR absorbing PbS quantum dots in combination with poly(3-hexylthiopene) and PCBM. We discuss different solution based deposition processes for device fabrication (spincoating, dip-coating, doctor blading, inkjet printing). Preliminary device tests result in a detectivity of 4.7.109 Jones at 1300 nm.

  5. Enhanced room temperature ferromagnetism in antiferromagnetic NiO nanoparticles

    SciTech Connect

    Ravikumar, Patta; Kisan, Bhagaban; Perumal, A.

    2015-08-15

    We report systematic investigations of structural, vibrational, resonance and magnetic properties of nanoscale NiO powders prepared by ball milling process under different milling speeds for 30 hours of milling. Structural properties revealed that both pure NiO and as-milled NiO powders exhibit face centered cubic structure, but average crystallite size decreases to around 11 nm along with significant increase in strain with increasing milling speed. Vibrational properties show the enhancement in the intensity of one-phonon longitudinal optical (LO) band and disappearance of two-magnon band due to size reduction. In addition, two-phonon LO band exhibits red shift due to size-induced phonon confinement effect and surface relaxation. Pure NiO powder exhibit antiferromagnetic nature, which transforms into induced ferromagnetic after size reduction. The average magnetization at room temperature increases with decreasing the crystallite size and a maximum moment of 0.016 μ{sub B}/f.u. at 12 kOe applied field and coercivity of 170 Oe were obtained for 30 hours milled NiO powders at 600 rotation per minute milling speed. The change in the magnetic properties is also supported by the vibrational properties. Thermomagnetization measurements at high temperature reveal a well-defined magnetic phase transition at high temperature (T{sub C}) around 780 K due to induced ferromagnetic phase. Electron paramagnetic resonance (EPR) studies reveal a good agreement between the EPR results and magnetic properties. The observed results are described on the basis of crystallite size variation, defect density, large strain, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion. The obtained results suggest that nanoscale NiO powders with high T{sub C} and moderate magnetic moment at room temperature with cubic structure would be useful to expedite for spintronic devices.

  6. Enhanced room temperature ferromagnetism in antiferromagnetic NiO nanoparticles

    NASA Astrophysics Data System (ADS)

    Ravikumar, Patta; Kisan, Bhagaban; Perumal, A.

    2015-08-01

    We report systematic investigations of structural, vibrational, resonance and magnetic properties of nanoscale NiO powders prepared by ball milling process under different milling speeds for 30 hours of milling. Structural properties revealed that both pure NiO and as-milled NiO powders exhibit face centered cubic structure, but average crystallite size decreases to around 11 nm along with significant increase in strain with increasing milling speed. Vibrational properties show the enhancement in the intensity of one-phonon longitudinal optical (LO) band and disappearance of two-magnon band due to size reduction. In addition, two-phonon LO band exhibits red shift due to size-induced phonon confinement effect and surface relaxation. Pure NiO powder exhibit antiferromagnetic nature, which transforms into induced ferromagnetic after size reduction. The average magnetization at room temperature increases with decreasing the crystallite size and a maximum moment of 0.016 μB/f.u. at 12 kOe applied field and coercivity of 170 Oe were obtained for 30 hours milled NiO powders at 600 rotation per minute milling speed. The change in the magnetic properties is also supported by the vibrational properties. Thermomagnetization measurements at high temperature reveal a well-defined magnetic phase transition at high temperature (TC) around 780 K due to induced ferromagnetic phase. Electron paramagnetic resonance (EPR) studies reveal a good agreement between the EPR results and magnetic properties. The observed results are described on the basis of crystallite size variation, defect density, large strain, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion. The obtained results suggest that nanoscale NiO powders with high TC and moderate magnetic moment at room temperature with cubic structure would be useful to expedite for spintronic devices.

  7. Room temperature homogeneous flow in a bulk metallic glass with low glass transition temperature

    NASA Astrophysics Data System (ADS)

    Zhao, K.; Xia, X. X.; Bai, H. Y.; Zhao, D. Q.; Wang, W. H.

    2011-04-01

    We report a high entropy metallic glass of Zn20Ca20Sr20Yb20(Li0.55Mg0.45)20 via composition design that exhibiting remarkable homogeneous deformation without shear banding under stress at room temperature. The glass also shows properties such as low glass transition temperature (323 K) approaching room temperature, low density and high specific strength, good conductivity, polymerlike thermoplastic manufacturability, and ultralow elastic moduli comparable to that of bones. The alloy is thermally and chemically stable.

  8. Room temperature homogeneous flow in a bulk metallic glass with low glass transition temperature

    SciTech Connect

    Zhao, K.; Xia, X. X.; Bai, H. Y.; Zhao, D. Q.; Wang, W. H.

    2011-04-04

    We report a high entropy metallic glass of Zn{sub 20}Ca{sub 20}Sr{sub 20}Yb{sub 20}(Li{sub 0.55}Mg{sub 0.45}){sub 20} via composition design that exhibiting remarkable homogeneous deformation without shear banding under stress at room temperature. The glass also shows properties such as low glass transition temperature (323 K) approaching room temperature, low density and high specific strength, good conductivity, polymerlike thermoplastic manufacturability, and ultralow elastic moduli comparable to that of bones. The alloy is thermally and chemically stable.

  9. Measurement by room-temperature phosphorescence of polynuclear aromatics containing hydrocarbon fuels that permeate glove materials

    SciTech Connect

    Gammage, R.B.; White, D.A.; Vo-Dinh, T.

    1986-01-01

    Permeations of commonly used glove materials by polynuclear aromatic (PNA) compounds in hydrocarbon fuels were measured with solid-state dosemeters composed of filter paper. The permeated PNA were sorbed by the filter paper and analyzed in situ using room-temperature phosphorescence spectroscopy. This technique provided a simple, cost-effective, and very sensitive means for measuring breakthrough times and permeation rates of the class of potentially carcinogenic PNA in liquid fuels derived from crude petroleum, oil shale, and coal. 7 refs., 3 figs.

  10. An efficient method for long-term room temperature storage of RNA

    PubMed Central

    Fabre, Anne-Lise; Colotte, Marthe; Luis, Aurélie; Tuffet, Sophie; Bonnet, Jacques

    2014-01-01

    RNA is a tool used in many fields, from molecular and cellular biology to medicine and nanotechnology. For most of these uses, the integrity of RNA is required and must be maintained during storage. Even though freezing is currently the storage method of choice, the increasing number of samples to be stored and the costly use of a cold chain have highlighted the need for room temperature preservation methods. Here, we report a new room temperature technology that consists in drying RNA samples in the presence of a stabilizer in stainless steel minicapsules. These air- and water-tight capsules isolate RNA from the atmosphere and maintain an anhydrous and anoxic environment. Through the evaluation of RNA integrity over time at room temperature or 90 °C, we identified atmospheric humidity as a major deleterious factor. The degradation rate dependence in temperature fitted an Arrhenius model, with an activation energy of 28.5 kcal/mol and an extrapolated room temperature degradation rate of 3.2 10−13/nt/s (95% confidence interval: 2.3–4.2/nt/s). In these conditions, it is expected that an RNA molecule will be subjected to 0.7–1.3 cut every 1000 nucleotides per century. In addition, we showed that stored RNA is compatible for further analyses, such as reverse transcription-quantitative PCR. No significant change in the Cq values was observed over a simulated period of several decades. At last, our data are consistent with a sequence-independent degradation rate of RNA in the solid state. PMID:23860045

  11. Adsorption of CO Molecules on Si(001) at Room Temperature

    NASA Astrophysics Data System (ADS)

    Seo, Eonmi; Eom, Daejin; Kim, Hanchul; Koo, Ja-Yong

    2015-03-01

    Initial adsorption of CO molecules on Si(001) is investigated by using room-temperature (RT) scanning tunneling microscopy (STM) and density functional theory calculations. Theoretical calculations show that only one adsorption configuration of terminal-bond CO (T-CO) is stable and that the bridge-bond CO is unstable. All the abundantly observed STM features due to CO adsorption can be identified as differently configured T-COs. The initial sticking probability of CO molecules on Si(001) at RT is estimated to be as small as ~ 1 x 10-4 monolayer/Langmuir, which is significantly increased at high-temperature adsorption experiments implying a finite activation barrier for adsorption. Thermal annealing at 900 K for 5 min results in the dissociation of the adsorbed CO molecules with the probability of 60-70% instead of desorption, indicating both a strong chemisorption state and an activated dissociation process. The unique adsorption state with a large binding energy, a tiny sticking probability, and a finite adsorption barrier is in stark contrast with the previous low-temperature (below 100 K) observations of a weak binding, a high sticking probability, and a barrierless adsorption. We speculate that the low-temperature results might be a signature of a physisorption state in the condensed phase.

  12. Advances in materials for room temperature hydrogen sensors.

    PubMed

    Arya, Sunil K; Krishnan, Subramanian; Silva, Hayde; Jean, Sheila; Bhansali, Shekhar

    2012-06-21

    Hydrogen (H(2)), as a source of energy, continues to be a compelling choice in applications ranging from fuel cells and propulsion systems to feedstock for chemical, metallurgical and other industrial processes. H(2), being a clean, reliable, and affordable source, is finding ever increasing use in distributed electric power generation and H(2) fuelled cars. Although still under 0.1%, the distributed use of H(2) is the fastest growing area. In distributed H(2) storage, distribution, and consumption, safety continues to be a critical aspect. Affordable safety systems for distributed H(2) applications are critical for the H(2) economy to take hold. Advances in H(2) sensors are driven by specificity, reliability, repeatability, stability, cost, size, response time, recovery time, operating temperature, humidity range, and power consumption. Ambient temperature sensors for H(2) detection are increasingly being explored as they offer specificity, stability and robustness of high temperature sensors with lower operational costs and significantly longer operational lifetimes. This review summarizes and highlights recent developments in room temperature H(2) sensors. PMID:22582176

  13. Electrically driven photon antibunching from a single molecule at room temperature.

    PubMed

    Nothaft, Maximilian; Höhla, Steffen; Jelezko, Fedor; Frühauf, Norbert; Pflaum, Jens; Wrachtrup, Jörg

    2012-01-01

    Single-photon emitters have been considered for applications in quantum information processing, quantum cryptography and metrology. For the sake of integration and to provide an electron photon interface, it is of great interest to stimulate single-photon emission by electrical excitation as demonstrated for quantum dots. Because of low exciton binding energies, it has so far not been possible to detect sub-Poissonian photon statistics of electrically driven quantum dots at room temperature. However, organic molecules possess exciton binding energies on the order of 1eV, thereby facilitating the development of an electrically driven single-photon source at room temperature in a solid-state matrix. Here we demonstrate electroluminescence of single, electrically driven molecules at room temperature. By careful choice of the molecular emitter, as well as fabrication of a specially designed organic light-emitting diode structure, we were able to achieve stable single-molecule emission and detect sub-Poissonian photon statistics. PMID:22252552

  14. Room temperature multiferroic properties of Eu doped BiFeO3

    NASA Astrophysics Data System (ADS)

    Uniyal, P.; Yadav, K. L.

    2009-04-01

    We have studied the multiferroic properties of Bi1-xEuxFeO3, x =0.03, 0.05, 0.07, and 0.1 ceramics prepared by conventional solid state reaction method. The substitution of Eu in place of Bi increases the magnetization at room temperature. An anomaly in the dielectric constant is observed at ˜400 °C which corresponds to TN. Room-temperature dielectric polarization-electric field (P-E) curves indicate that higher doped compositions exhibit saturated P-E loops with Pr (remnant polarization) of these BFO-based samples increasing with the degree of Eu modification. As a result, improved multiferroic properties of the Bi0.9Eu0.1FeO3 ceramics with remnant polarization and magnetization (Pr and Mr) of 11 μC/cm2 and 0.0347 emu/g, respectively, were obtained. The evidence of weak ferromagnetism and saturated ferroelectric hysteresis loops in Bi1-xEuxFeO3 system at room temperature makes it a good candidate for potential applications.

  15. Contracting cardiomyocytes in hydrophobic room-temperature ionic liquid

    SciTech Connect

    Hoshino, Takayuki; Fujita, Kyoko; Higashi, Ayako; Sakiyama, Keiko; Ohno, Hiroyuki; Morishima, Keisuke

    2012-10-19

    Highlights: Black-Right-Pointing-Pointer Biocompatible room-temperature ionic liquid was applied on beating cardiomyocyte. Black-Right-Pointing-Pointer The lifetime of beating cardiomyocytes was depended on anion functional group. Black-Right-Pointing-Pointer A longer lifetime was recorded for no functional group on alkyl chain on their anion. Black-Right-Pointing-Pointer Amino group on alkyl chain and fluorine in anion induced fatal condition changes. Black-Right-Pointing-Pointer We reported liquid electrolyte interface to stimulate cardiomyocytes. -- Abstract: Room-temperature ionic liquids (RTILs) are drawing attention as a new class of nonaqueous solvents to replace organic and aqueous solvents for chemical processes in the liquid phase at room temperature. The RTILs are notable for their characteristics of nonvolatility, extremely low vapor pressure, electric conductivity, and incombustibility. These distinguished properties of RTILs have brought attention to them in applications with biological cells and tissue in vacuum environment for scanning electron microscopy, and in microfluidic devices for micro-total analysis system (micro-TAS). Habitable RTILs could increase capability of nonaqueous micro-TAS for living cells. Some RTILs seemed to have the capability to replace water in biological applications. However, these RTILs had been applied to just supplemental additives for biocompatible test, to fixed cells as a substitute for an aqueous solution, and to simple molecules. None of RTILs in which directly soaks a living cell culture. Therefore, we demonstrated the design of RTILs for a living cell culture and a liquid electrolyte to stimulate contracting cardiomyocytes using the RTILs. We assessed the effect of RTILs on the cardiomyocytes using the beating lifetime to compare the applicability of RTILs for biological applications. Frequent spontaneous contractions of cardiomyocytes were confirmed in amino acid anion RTILs [P{sub 8,8,8,8}][Leu] and [P{sub 8

  16. Intermediate temperature solid oxide fuel cells.

    PubMed

    Brett, Daniel J L; Atkinson, Alan; Brandon, Nigel P; Skinner, Stephen J

    2008-08-01

    High temperature solid oxide fuel cells (SOFCs), typified by developers such as Siemens Westinghouse and Rolls-Royce, operate in the temperature region of 850-1000 degrees C. For such systems, very high efficiencies can be achieved from integration with gas turbines for large-scale stationary applications. However, high temperature operation means that the components of the stack need to be predominantly ceramic and high temperature metal alloys are needed for many balance-of-plant components. For smaller scale applications, where integration with a heat engine is not appropriate, there is a trend to move to lower temperatures of operation, into the so-called intermediate temperature (IT) range of 500-750 degrees C. This expands the choice of materials and stack geometries that can be used, offering reduced system cost and, in principle, reducing the corrosion rate of stack and system components. This review introduces the IT-SOFC and explains the advantages of operation in this temperature regime. The main advances made in materials chemistry that have made IT operation possible are described and some of the engineering issues and the new opportunities that reduced temperature operation affords are discussed. This tutorial review examines the advances being made in materials and engineering that are allowing solid oxide fuel cells to operate at lower temperature. The challenges and advantages of operating in the so-called 'intermediate temperature' range of 500-750 degrees C are discussed and the opportunities for applications not traditionally associated with solid oxide fuel cells are highlighted. This article serves as an introduction for scientists and engineers interested in intermediate temperature solid oxide fuel cells and the challenges and opportunities of reduced temperature operation. PMID:18648682

  17. Tailoring room temperature photoluminescence of antireflective silicon nanofacets

    SciTech Connect

    Basu, Tanmoy; Kumar, M.; Ghatak, J.; Som, T.; Kanjilal, A.; Sahoo, P. K.

    2014-09-21

    In this paper, a fluence-dependent antireflection performance is presented from ion-beam fabricated nanofaceted-Si surfaces. It is also demonstrated that these nanofacets are capable of producing room temperature ultra-violet and blue photoluminescence which can be attributed to inter-band transitions of the localized excitonic states of different Si-O bonds at the Si/SiO{sub x} interface. Time-resolved photoluminescence measurements further confirm defect-induced radiative emission from the surface of silicon nanofacets. It is observed that the spectral characteristics remain unchanged, except an enhancement in the photoluminescence intensity with increasing ion-fluence. The increase in photoluminescence intensity by orders of magnitude stronger than that of a planar Si substrate is due to higher absorption of incident photons by nanofaceted structures.

  18. Modification of embedded Cu nanoparticles: Ion irradiation at room temperature

    NASA Astrophysics Data System (ADS)

    Johannessen, B.; Kluth, P.; Giulian, R.; Araujo, L. L.; Llewellyn, D. J.; Foran, G. J.; Cookson, D. J.; Ridgway, M. C.

    2007-04-01

    Cu nanoparticles (NPs) with an average diameter of ∼25 Å were synthesized in SiO2 by ion implantation and thermal annealing. Subsequently, the NPs were exposed to ion irradiation at room temperature simultaneously with a bulk Cu reference film. The ion species/energy was varied to achieve different values for the nuclear energy loss. The short-range atomic structure and average NP diameter were measured by means of extended X-ray absorption fine structure spectroscopy and small angle X-ray scattering, respectively. Transmission electron microscopy yielded complementary results. The short-range order of the Cu films remained unchanged consistent with the high regeneration rate of bulk elemental metals. For the NP samples it was found that increasing nuclear energy loss yielded gradual dissolution of NPs. Furthermore, an increased structural disorder was observed for the residual NPs.

  19. Defects in silicon plastically deformed at room temperature

    NASA Astrophysics Data System (ADS)

    Leipner, H. S.; Wang, Z.; Gu, H.; Mikhnovich, V. V., Jr.; Bondarenko, V.; Krause-Rehberg, R.; Demenet, J.-L.; Rabier, J.

    2004-07-01

    The article [1] describes specific features of positron trapping in silicon plastically deformed at room temperature. The results are related to the dislocation core structure and the inhomogeneous deformation. The picture shows the probability density function of a positron localized in a vacancy in silicon. The calculation was performed with the superimposed-atom model. The degree of localization and consequently the defect-related positron lifetime vary for different open-volume defects, such as vacancies, voids, and dislocations.The first author, Hartmut S. Leipner, is CEO of the Center of Materials Science of the University Halle-Wittenberg. His research activities are focused on the characterization of extended defects in semiconductors.

  20. Emergence of room-temperature ferroelectricity at reduced dimensions.

    PubMed

    Lee, D; Lu, H; Gu, Y; Choi, S-Y; Li, S-D; Ryu, S; Paudel, T R; Song, K; Mikheev, E; Lee, S; Stemmer, S; Tenne, D A; Oh, S H; Tsymbal, E Y; Wu, X; Chen, L-Q; Gruverman, A; Eom, C B

    2015-09-18

    The enhancement of the functional properties of materials at reduced dimensions is crucial for continuous advancements in nanoelectronic applications. Here, we report that the scale reduction leads to the emergence of an important functional property, ferroelectricity, challenging the long-standing notion that ferroelectricity is inevitably suppressed at the scale of a few nanometers. A combination of theoretical calculations, electrical measurements, and structural analyses provides evidence of room-temperature ferroelectricity in strain-free epitaxial nanometer-thick films of otherwise nonferroelectric strontium titanate (SrTiO3). We show that electrically induced alignment of naturally existing polar nanoregions is responsible for the appearance of a stable net ferroelectric polarization in these films. This finding can be useful for the development of low-dimensional material systems with enhanced functional properties relevant to emerging nanoelectronic devices. PMID:26383947

  1. Realization of a flux-driven memtranstor at room temperature

    NASA Astrophysics Data System (ADS)

    Shi-Peng, Shen; Da-Shan, Shang; Yi-Sheng, Chai; Young, Sun

    2016-02-01

    The memtranstor has been proposed to be the fourth fundamental circuit memelement in addition to the memristor, memcapacitor, and meminductor. Here, we demonstrate the memtranstor behavior at room temperature in a device made of the magnetoelectric hexaferrite (Ba0.5Sr1.5Co2Fe11AlO22) where the electric polarization is tunable by external magnetic field. This device shows a nonlinear q-φ relationship with a butterfly-shaped hysteresis loop, in agreement with the anticipated memtranstor behavior. The memtranstor, like other memelements, has a great potential in developing more advanced circuit functionalities. Project supported by the National Natural Science Foundation of China (Grants Nos. 11227405, 11534015, 11274363, and 11374347) and the Natural Science Foundation from the Chinese Academy of Sciences (Grant No. XDB07030200).

  2. Calculation of the room-temperature shapes of unsymmetric laminates

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.

    1981-01-01

    A theory explaining the characteristics of the cured shapes of unsymmetric laminates is presented. The theory is based on an extension of classical lamination theory which accounts for geometric nonlinearities. A Rayleigh-Ritz approach to minimizing the total potential energy is used to obtain quantitative information regarding the room temperature shapes of square T300/5208 (0(2)/90(2))T and (0(4)/90(4))T graphite-epoxy laminates. It is shown that, depending on the thickness of the laminate and the length of the side the square, the saddle shape configuration is actually unstable. For values of length and thickness that render the saddle shape unstable, it is shown that two stable cylindrical shapes exist. The predictions of the theory are compared with existing experimental data.

  3. Microstructure of room temperature ionic liquids at stepped graphite electrodes

    SciTech Connect

    Feng, Guang; Li, Song; Zhao, Wei; Cummings, Peter T.

    2015-07-14

    Molecular dynamics simulations of room temperature ionic liquid (RTIL) [emim][TFSI] at stepped graphite electrodes were performed to investigate the influence of the thickness of the electrode surface step on the microstructure of interfacial RTILs. A strong correlation was observed between the interfacial RTIL structure and the step thickness in electrode surface as well as the ion size. Specifically, when the step thickness is commensurate with ion size, the interfacial layering of cation/anion is more evident; whereas, the layering tends to be less defined when the step thickness is close to the half of ion size. Furthermore, two-dimensional microstructure of ion layers exhibits different patterns and alignments of counter-ion/co-ion lattice at neutral and charged electrodes. As the cation/anion layering could impose considerable effects on ion diffusion, the detailed information of interfacial RTILs at stepped graphite presented here would help to understand the molecular mechanism of RTIL-electrode interfaces in supercapacitors.

  4. Room-temperature ferromagnetism in cerium dioxide powders

    NASA Astrophysics Data System (ADS)

    Rakhmatullin, R. M.; Pavlov, V. V.; Semashko, V. V.; Korableva, S. L.

    2015-08-01

    Room-temperature ferromagnetism is detected in a CeO2 powder with a grain size of about 35 nm and a low (<0.1 at %) manganese and iron content. The ferromagnetism in a CeO2 sample with a submicron crystallite size and the same manganese and iron impurity content is lower than in the nanocrystalline sample by an order of magnitude. Apart from ferromagnetism, both samples exhibit EPR spectra of localized paramagnetic centers, the concentration of which is lower than 0.01 at %. A comparative analysis of these results shows that the F-center exchange (FCE) mechanism cannot cause ferromagnetism. This conclusion agrees with the charge-transfer ferromagnetism model proposed recently.

  5. Oxidative decomposition of formaldehyde by metal oxides at room temperature

    NASA Astrophysics Data System (ADS)

    Sekine, Yoshika

    Formaldehyde (HCHO) is still a major indoor air pollutant in Japanese air-tight houses and is the subject of numerous complaints regarding health disorders. Authors have developed a passive-type air-cleaning material and an air cleaner using manganese oxide (77% MnO 2) as an active component and successfully reduced indoor HCHO concentrations in newly built multi-family houses. In this study, the reactivity between manganese oxide and HCHO was discussed. We tested the removal efficiencies of several metal oxides for HCHO in a static reaction vessel and found manganese oxide could react with HCHO and release carbon dioxide even at room temperature. The reactivity and mechanisms were discussed for the proposed chemical reactions. A mass balance study proved that a major product through the heterogeneous reaction between manganese oxide and HCHO was carbon dioxide. Harmful by-products (HCOOH and CO) were not found.

  6. Ratcheting fatigue behavior of Zircaloy-2 at room temperature

    NASA Astrophysics Data System (ADS)

    Rajpurohit, R. S.; Sudhakar Rao, G.; Chattopadhyay, K.; Santhi Srinivas, N. C.; Singh, Vakil

    2016-08-01

    Nuclear core components of zirconium alloys experience asymmetric stress or strain cycling during service which leads to plastic strain accumulation and drastic reduction in fatigue life as well as dimensional instability of the component. Variables like loading rate, mean stress, and stress amplitude affect the influence of asymmetric loading. In the present investigation asymmetric stress controlled fatigue tests were conducted with mean stress from 80 to 150 MPa, stress amplitude from 270 to 340 MPa and stress rate from 30 to 750 MPa/s to study the process of plastic strain accumulation and its effect on fatigue life of Zircaloy-2 at room temperature. It was observed that with increase in mean stress and stress amplitude accumulation of ratcheting strain was increased and fatigue life was reduced. However, increase in stress rate led to improvement in fatigue life due to less accumulation of ratcheting strain.

  7. Observation of visible luminescence from indium nitride at room temperature

    SciTech Connect

    Guo, Q.X.; Tanaka, T.; Nishio, M.; Ogawa, H.; Pu, X.D.; Shen, W.Z.

    2005-06-06

    InN films were grown on sapphire substrates with AlN buffer layers by reactive sputtering. C-axis-oriented crystalline InN films with a wurtzite structure were confirmed by x-ray diffraction and Raman scattering. Strong photoluminescence (PL) at 1.87 eV, together with a clear absorption edge at 1.97 eV, was observed at room temperature, which clearly demonstrates that it is not accurate in the previous assignment of an {approx}0.7 eV fundamental band gap for intrinsic InN simply from PL and absorption data. The possible origin of the present large band gap was discussed in terms of the effects of oxygen and the Burstein-Moss shift.

  8. Room temperature mechanical properties of shuttle thermal protection system materials

    NASA Technical Reports Server (NTRS)

    Sawyer, J. W.; Rummler, D. R.

    1980-01-01

    Tests were conducted at room temperature to determine the mechanical properties and behavior of materials used for the thermal protection system of the space shuttle. The materials investigated include the LI-900 RSI tiles, the RTV-560 adhesive and the .41 cm (.16 thick) strain isolator pad (SIP). Tensile and compression cyclic loading tests were conducted on the SIP material and stress-strain curves obtained for various proof loads and load cyclic conditioning. Ultimate tensile and shear tests were conducted on the RSI, RTV, and SIP materials. The SIP material exhibits highly nonlinear stress-strain behavior, increased tangent modulus and ultimate tensile strength with increased loading rate, and large short time load relaxation and moderate creep behavior. Proof and cyclic load conditioning of the SIP results in permanent deformation of the material, hysteresis effects, and much higher tensile tangent modulus values at large strains.

  9. Room-temperature ferromagnetism in graphitic petal arrays.

    PubMed

    Rout, Chandra Sekhar; Kumar, Anurag; Kumar, Nitesh; Sundaresan, A; Fisher, Timothy S

    2011-03-01

    We report room-temperature ferromagnetism of graphitic petal arrays grown on Si substrates by microwave plasma chemical vapor deposition without catalyst. The samples have been characterized by Raman and X-ray photoelectron spectroscopy to confirm the absence of possible ferromagnetic impurities. The petals exhibit ferromagnetic hysteresis with saturation magnetization of ∼4.67 emu cm(-3) and coercivity of ∼105 Oe at 300 K, comparable to the reported behavior of few-layer graphene. Upon O2 annealing the saturation magnetization and coercivity decreased to 2.1 emu cm(-3) and ∼75 Oe respectively. The origin of ferromagnetism is believed to arise from the edge defects and vacancies in the petals. PMID:21264436

  10. Room-temperature ferromagnetism in graphitic petal arrays

    NASA Astrophysics Data System (ADS)

    Rout, Chandra Sekhar; Kumar, Anurag; Kumar, Nitesh; Sundaresan, A.; Fisher, Timothy S.

    2011-03-01

    We report room-temperature ferromagnetism of graphitic petal arrays grown on Si substrates by microwave plasma chemical vapor deposition without catalyst. The samples have been characterized by Raman and X-ray photoelectron spectroscopy to confirm the absence of possible ferromagnetic impurities. The petals exhibit ferromagnetic hysteresis with saturation magnetization of ~4.67 emu cm-3 and coercivity of ~105 Oe at 300 K, comparable to the reported behavior of few-layer graphene. Upon O2 annealing the saturation magnetization and coercivity decreased to 2.1 emu cm-3 and ~75 Oe respectively. The origin of ferromagnetism is believed to arise from the edge defects and vacancies in the petals.

  11. Thermoelectricity in atom-sized junctions at room temperatures

    PubMed Central

    Tsutsui, Makusu; Morikawa, Takanori; Arima, Akihide; Taniguchi, Masateru

    2013-01-01

    Atomic and molecular junctions are an emerging class of thermoelectric materials that exploit quantum confinement effects to obtain an enhanced figure of merit. An important feature in such nanoscale systems is that the electron and heat transport become highly sensitive to the atomic configurations. Here we report the characterization of geometry-sensitive thermoelectricity in atom-sized junctions at room temperatures. We measured the electrical conductance and thermoelectric power of gold nanocontacts simultaneously down to the single atom size. We found junction conductance dependent thermoelectric voltage oscillations with period 2e2/h. We also observed quantum suppression of thermovoltage fluctuations in fully-transparent contacts. These quantum confinement effects appeared only statistically due to the geometry-sensitive nature of thermoelectricity in the atom-sized junctions. The present method can be applied to various nanomaterials including single-molecules or nanoparticles and thus may be used as a useful platform for developing low-dimensional thermoelectric building blocks. PMID:24270238

  12. Thermoelectricity in atom-sized junctions at room temperatures.

    PubMed

    Tsutsui, Makusu; Morikawa, Takanori; Arima, Akihide; Taniguchi, Masateru

    2013-01-01

    Atomic and molecular junctions are an emerging class of thermoelectric materials that exploit quantum confinement effects to obtain an enhanced figure of merit. An important feature in such nanoscale systems is that the electron and heat transport become highly sensitive to the atomic configurations. Here we report the characterization of geometry-sensitive thermoelectricity in atom-sized junctions at room temperatures. We measured the electrical conductance and thermoelectric power of gold nanocontacts simultaneously down to the single atom size. We found junction conductance dependent thermoelectric voltage oscillations with period 2e(2)/h. We also observed quantum suppression of thermovoltage fluctuations in fully-transparent contacts. These quantum confinement effects appeared only statistically due to the geometry-sensitive nature of thermoelectricity in the atom-sized junctions. The present method can be applied to various nanomaterials including single-molecules or nanoparticles and thus may be used as a useful platform for developing low-dimensional thermoelectric building blocks. PMID:24270238

  13. Theory of room temperature ferromagnetism in Cr modified DNA nanowire

    NASA Astrophysics Data System (ADS)

    Paruğ Duru, Izzet; Değer, Caner; Eldem, Vahap; Kalayci, Taner; Aktaş, Şahin

    2016-04-01

    We investigated the magnetic properties of Cr3+ (J  <  0) ion-modified DNA (M-DNA) nanowire (1000 base) at room temperature under a uniform magnetic field (˜100 Oe) for different doping concentrations. A Monte Carlo simulation method-based Metropolis algorithm is used to figure out the thermodynamic quantities of nanowire formed by Cr M-DNA followed by analysing the dependency of the ferromagnetic behaviour of the M-DNA to dopant concentration. It is understood that ion density/base and ion density/helical of Cr3+ ions can be a tuning parameter, herewith the dopant ratio has an actual importance on the magnetic characterization of M-DNA nanowire (3%-20%). We propose the source of magnetism as an exchange interaction between Cr and DNA helical atoms indicated in the Heisenberg Hamiltonian.

  14. Complete S matrix in a microwave cavity at room temperature.

    PubMed

    Barthélemy, Jérôme; Legrand, Olivier; Mortessagne, Fabrice

    2005-01-01

    We experimentally study the widths of resonances in a two-dimensional microwave cavity at room temperature. By developing a model for the coupling antennas, we are able to discriminate their contribution from those of Ohmic losses to the broadening of resonances. Concerning Ohmic losses, we experimentally put to evidence two mechanisms: damping along propagation and absorption at the contour, the latter being responsible for variations of widths from mode to mode due to its dependence on the spatial distribution of the field at the contour. A theory, based on an S -matrix formalism, is given for these variations. It is successfully validated through measurements of several hundreds of resonances in a rectangular cavity. PMID:15697696

  15. Electrically Injected Photon-Pair Source at Room Temperature

    NASA Astrophysics Data System (ADS)

    Boitier, Fabien; Orieux, Adeline; Autebert, Claire; Lemaître, Aristide; Galopin, Elisabeth; Manquest, Christophe; Sirtori, Carlo; Favero, Ivan; Leo, Giuseppe; Ducci, Sara

    2014-05-01

    One of the main challenges for future quantum information technologies is the miniaturization and integration of high performance components in a single chip. In this context, electrically driven sources of nonclassical states of light have a clear advantage over optically driven ones. Here we demonstrate the first electrically driven semiconductor source of photon pairs working at room temperature and telecom wavelengths. The device is based on type-II intracavity spontaneous parametric down-conversion in an AlGaAs laser diode and generates pairs at 1.57 μm. Time-correlation measurements of the emitted pairs give an internal generation efficiency of 7×10-11 pairs/injected electron. The capability of our platform to support the generation, manipulation, and detection of photons opens the way to the demonstration of massively parallel systems for complex quantum operations.

  16. Simultaneous measurement of force and tunneling current at room temperature

    NASA Astrophysics Data System (ADS)

    Sawada, Daisuke; Sugimoto, Yoshiaki; Morita, Ken-ichi; Abe, Masayuki; Morita, Seizo

    2009-04-01

    We have performed simultaneous scanning tunneling microscopy and atomic force microscopy measurements in the dynamic mode using metal-coated Si cantilevers at room temperature. Frequency shift (Δf) and time-average tunneling current (⟨It⟩) images are obtained by tip scanning on the Si(111)-(7×7) surface at constant height mode. By measuring site-specific Δf(⟨It⟩) versus tip-surface distance curves, we derive the force (tunneling current) at the closest separation between the sample surface and the oscillating tip. We observe the drop in the tunneling current due to the chemical interaction between the tip apex atom and the surface adatom, which was found recently, and estimate the value of the chemical bonding force. Scanning tunneling spectroscopy using the same tip shows that the tip is metallic enough to measure local density of states of electrons on the surface.

  17. Cavity-Enhanced Room-Temperature Broadband Raman Memory.

    PubMed

    Saunders, D J; Munns, J H D; Champion, T F M; Qiu, C; Kaczmarek, K T; Poem, E; Ledingham, P M; Walmsley, I A; Nunn, J

    2016-03-01

    Broadband quantum memories hold great promise as multiplexing elements in future photonic quantum information protocols. Alkali-vapor Raman memories combine high-bandwidth storage, on-demand readout, and operation at room temperature without collisional fluorescence noise. However, previous implementations have required large control pulse energies and have suffered from four-wave-mixing noise. Here, we present a Raman memory where the storage interaction is enhanced by a low-finesse birefringent cavity tuned into simultaneous resonance with the signal and control fields, dramatically reducing the energy required to drive the memory. By engineering antiresonance for the anti-Stokes field, we also suppress the four-wave-mixing noise and report the lowest unconditional noise floor yet achieved in a Raman-type warm vapor memory, (15±2)×10^{-3} photons per pulse, with a total efficiency of (9.5±0.5)%. PMID:26991164

  18. Cavity-Enhanced Room-Temperature Broadband Raman Memory

    NASA Astrophysics Data System (ADS)

    Saunders, D. J.; Munns, J. H. D.; Champion, T. F. M.; Qiu, C.; Kaczmarek, K. T.; Poem, E.; Ledingham, P. M.; Walmsley, I. A.; Nunn, J.

    2016-03-01

    Broadband quantum memories hold great promise as multiplexing elements in future photonic quantum information protocols. Alkali-vapor Raman memories combine high-bandwidth storage, on-demand readout, and operation at room temperature without collisional fluorescence noise. However, previous implementations have required large control pulse energies and have suffered from four-wave-mixing noise. Here, we present a Raman memory where the storage interaction is enhanced by a low-finesse birefringent cavity tuned into simultaneous resonance with the signal and control fields, dramatically reducing the energy required to drive the memory. By engineering antiresonance for the anti-Stokes field, we also suppress the four-wave-mixing noise and report the lowest unconditional noise floor yet achieved in a Raman-type warm vapor memory, (15 ±2 )×10-3 photons per pulse, with a total efficiency of (9.5 ±0.5 )%.

  19. Room-temperature ferromagnetism in cerium dioxide powders

    SciTech Connect

    Rakhmatullin, R. M. Pavlov, V. V.; Semashko, V. V.; Korableva, S. L.

    2015-08-15

    Room-temperature ferromagnetism is detected in a CeO{sub 2} powder with a grain size of about 35 nm and a low (<0.1 at %) manganese and iron content. The ferromagnetism in a CeO{sub 2} sample with a submicron crystallite size and the same manganese and iron impurity content is lower than in the nanocrystalline sample by an order of magnitude. Apart from ferromagnetism, both samples exhibit EPR spectra of localized paramagnetic centers, the concentration of which is lower than 0.01 at %. A comparative analysis of these results shows that the F-center exchange (FCE) mechanism cannot cause ferromagnetism. This conclusion agrees with the charge-transfer ferromagnetism model proposed recently.

  20. Gas sensing properties of nanocrystalline diamond at room temperature

    PubMed Central

    Kulha, Pavel; Laposa, Alexandr; Hruska, Karel; Demo, Pavel; Kromka, Alexander

    2014-01-01

    Summary This study describes an integrated NH3 sensor based on a hydrogenated nanocrystalline diamond (NCD)-sensitive layer coated on an interdigitated electrode structure. The gas sensing properties of the sensor structure were examined using a reducing gas (NH3) at room temperature and were found to be dependent on the electrode arrangement. A pronounced response of the sensor, which was comprised of dense electrode arrays (of 50 µm separation distance), was observed. The sensor functionality was explained by the surface transfer doping effect. Moreover, the three-dimensional model of the current density distribution of the hydrogenated NCD describes the transient flow of electrons between interdigitated electrodes and the hydrogenated NCD surface, that is, the formation of a closed current loop. PMID:25551062

  1. Room-Temperature, Low-Barrier Boron Doping of Graphene.

    PubMed

    Pan, Lida; Que, Yande; Chen, Hui; Wang, Dongfei; Li, Jun; Shen, Chengmin; Xiao, Wende; Du, Shixuan; Gao, Hongjun; Pantelides, Sokrates T

    2015-10-14

    Doping graphene with boron has been difficult because of high reaction barriers. Here, we describe a low-energy reaction route derived from first-principles calculations and validated by experiments. We find that a boron atom on graphene on a ruthenium(0001) substrate can replace a carbon by pushing it through, with substrate attraction helping to reduce the barrier to only 0.1 eV, implying that the doping can take place at room temperature. High-quality graphene is grown on a Ru(0001) surface and exposed to B2H6. Scanning tunneling microscopy/spectroscopy and X-ray photoelectron spectroscopy confirmed that boron is indeed incorporated substitutionally without disturbing the graphene lattice. PMID:26348981

  2. Energy resolution improvement in room-temperature CZT detectors

    NASA Astrophysics Data System (ADS)

    Ramachers, Y.; Stewart, D. Y.

    2007-12-01

    We present methods to improve the energy resolution of single channel, room-temperature Cadmium-Zinc-Telluride (CZT) detectors. A new preamplifier design enables the acquisition of the actual transient current from the crystals and straightforward data analysis methods yield unprecedented energy resolution for our test-detectors. These consist of an eV-CAPture Plus crystal as standard and 1 cm cube Frisch collar crystals created in-house from low-grade coplanar grid detectors. Energy resolutions of 1.9% for our collar detectors and 0.8% for the eV crystal at 662 keV were obtained. The latter compares favourably to the best existing energy resolution results from pixel detectors.

  3. Room-temperature terahertz oscillation of resonant tunneling diodes

    NASA Astrophysics Data System (ADS)

    Asada, Masahiro; Suzuki, Safumi

    2013-09-01

    Our recent results of room-temperature THz oscillators using resonant tunneling diodes (RTDs) are reported. This oscillator is composed of a GaInAs/AlAs double-barrier RTD and a planar slot antenna. The maximum oscillation frequency in RTDs is limited by the electron delay time across the RTD layers, which consists of the dwell time in the resonant tunneling region and the transit time across the collector depletion region. The dwell time was reduced by a narrow quantum well, and a fundamental oscillation up to 1.31 THz with the output power of 10 μW was achieved at room temperature. Further increase in oscillation frequency is expected by optimized size and materials of the well and barriers for the dwell time and those of the collector depletion layer for the transit time. By these improvements, a fundamental oscillation up to around 2 THz is theoretically possible. For high output power, coherent power combining was demonstrated in a two-element array with offset slot antennas coupled with each other, and 610 μW at 620 GHz was obtained. Spectral characteristics were measured with a heterodyne detection, and the linewidth of less than 10 MHz was obtained. A frequency change of 1-5 % with bias voltage was also observed, which is attributed to the bias-dependent dwell time. Direct intensity modulation and wireless data transmission were demonstrated. A transmission rate of 3 Gbps with the bit error rate of 3×10-5 was obtained at 540 GHz in a preliminary experiment, which is limited by the frequency characteristics of external modulation circuits at present.

  4. Contracting cardiomyocytes in hydrophobic room-temperature ionic liquid.

    PubMed

    Hoshino, Takayuki; Fujita, Kyoko; Higashi, Ayako; Sakiyama, Keiko; Ohno, Hiroyuki; Morishima, Keisuke

    2012-10-19

    Room-temperature ionic liquids (RTILs) are drawing attention as a new class of nonaqueous solvents to replace organic and aqueous solvents for chemical processes in the liquid phase at room temperature. The RTILs are notable for their characteristics of nonvolatility, extremely low vapor pressure, electric conductivity, and incombustibility. These distinguished properties of RTILs have brought attention to them in applications with biological cells and tissue in vacuum environment for scanning electron microscopy, and in microfluidic devices for micro-total analysis system (micro-TAS). Habitable RTILs could increase capability of nonaqueous micro-TAS for living cells. Some RTILs seemed to have the capability to replace water in biological applications. However, these RTILs had been applied to just supplemental additives for biocompatible test, to fixed cells as a substitute for an aqueous solution, and to simple molecules. None of RTILs in which directly soaks a living cell culture. Therefore, we demonstrated the design of RTILs for a living cell culture and a liquid electrolyte to stimulate contracting cardiomyocytes using the RTILs. We assessed the effect of RTILs on the cardiomyocytes using the beating lifetime to compare the applicability of RTILs for biological applications. Frequent spontaneous contractions of cardiomyocytes were confirmed in amino acid anion RTILs [P(8,8,8,8)][Leu] and [P(8,8,8,8)][Ala], phosphoric acid derivatives [P(8,8,8,8)][MeO(H)PO(2)], and [P(8,8,8,8)][C(7)CO(2)]. The anion type of RTILs had influence on applicable characteristics for the contracting cardiomyocyte. This result suggested the possibility for biocompatible design of hydrophobic group RTILs to achieve biological applications with living cells. PMID:23000154

  5. Room Temperature Ferroelectricity in Ultrathin SnTe Films

    NASA Astrophysics Data System (ADS)

    Chang, Kai; Liu, Junwei; Lin, Haicheng; Zhao, Kun; Zhong, Yong; Ji, Shuai-Hua; He, Ke; Wang, Lili; Ma, Xucun; Fu, Liang; Chen, Xi; Xue, Qi-Kun

    2015-03-01

    The ultrathin SnTe films with several unit cell thickness grown on graphitized SiC(0001) surface have been studied by the scanning tunneling microscopy and spectroscopy (STM/S). The domain structures, local lattice distortion and the electronic band bending at film edges induced by the in-plane spontaneous polarization along < 110 > have been revealed at atomic scale. The experiments at variant temperature show that the Curie temperature Tc of the one unit cell thick (two atomic layers) SnTe film is as high as 280K, much higher than that of the bulk counterpart (~100K) and the 2-4 unit cell thick films even indicate robust ferroelectricity at room temperature. This Tc enhancement is attributed to the stress-free interface, larger electronic band gap and greatly reduced Sn vacancy concentration in the ultrathin films. The lateral domain size varies from several tens to several hundreds of nanometers, and the spontaneous polarization direction could be modified by STM tip. Those properties of ultrathin SnTe films show the potential application on ferroelectric devices. The work was financially supported by Ministry of Science and Technology of China, National Science Foundation and Ministry of Education of China.

  6. A glass microfluidic chip adhesive bonding method at room temperature

    NASA Astrophysics Data System (ADS)

    Pan, Yu-Jen; Yang, Ruey-Jen

    2006-12-01

    This paper presents a novel method using UV epoxy resin for the bonding of glass blanks and patterned plates at room temperature. There is no need to use a high-temperature thermal fusion process and therefore avoid damaging temperature-sensitive metals in a microchip. The proposed technique has the further advantage that the sealed glass blanks and patterned plates can be separated by the application of adequate heat. In this way, the microchip can be opened, the fouling microchannels may be easily cleaned-up and the plates then re-bonded to recycle the microchip. The proposed sealing method is used to bond a microfluidic device, and the bonding strength is then investigated in a series of chemical resistance tests conducted in various chemicals. Leakage of solution was evaluated in a microfluidic chip using pressure testing to 1.792 × 102 kPa (26 psi), and the microchannel had no observable leak. Electrical leakage between channels was tested by comparing the resistances of two bonding methods, and the result shows no significant electrical leakage. The performance of the device obtained from the proposed bonding method is compared with that of the thermal fusion bonding technique for an identical microfluidic device. It is found that identical results are obtained under the same operating conditions. The proposed method provides a simple, quick and inexpensive method for sealing glass microfluidic chips.

  7. AN-107 entrained solids - Solubility versus temperature

    SciTech Connect

    GJ Lumetta; RC Lettau

    2000-03-31

    This report describes the results of a test conducted by Battelle to assess the solubility of the solids entrained in the diluted AN-107 low-activity waste (LAW) sample. BNFL requested Battelle to dilute the AN-107 sample using sodium hydroxide and de-ionized water to mimic expected plant operating conditions. BNFL further requested Battelle to assess the solubility of the solids present in the diluted AN-107 sample versus temperature conditions of 30, 40, and 50 C. BNFL requested these tests to assess the composition of the LAW supernatant and solids versus expected plant-operating conditions.

  8. Visible room-temperature phosphorescence of pure organic crystals via a radical-ion-pair mechanism.

    PubMed

    Kuno, Shinichi; Akeno, Hiroshi; Ohtani, Hiroyuki; Yuasa, Hideya

    2015-06-28

    The afterglow of phosphorescent compounds can be distinguished from background fluorescence and scattered light by a time-resolved observation, which is a beneficial property for bioimaging. Phosphorescence emission accompanies spin-forbidden transitions from an excited singlet state through an excited triplet state to a ground singlet state. Since these intersystem crossings are facilitated usually by the heavy-atom effect, metal-free organic solids are seldom phosphorescent, although these solids have recently been refurbished as low-cost, eco-friendly phosphorescent materials. Here, we show that crystalline isophthalic acid exhibits room-temperature phosphorescence with an afterglow that lasts several seconds through a nuclear spin magnetism-assisted spin exchange of a radical ion pair. The obvious afterglow that facilitates a time-resolved detection and the unusual phosphorescence mechanism that enables emission intensification by nuclear spin managements are promising for exploiting the phosphorescence materials in novel applications such as bioimaging. PMID:26027521

  9. Room temperature manipulation of long lifetime spins in metallic-like carbon nanospheres.

    PubMed

    Náfrádi, Bálint; Choucair, Mohammad; Dinse, Klaus-Peter; Forró, László

    2016-01-01

    The time-window for processing electron spin information (spintronics) in solid-state quantum electronic devices is determined by the spin-lattice and spin-spin relaxation times of electrons. Minimizing the effects of spin-orbit coupling and the local magnetic contributions of neighbouring atoms on spin-lattice and spin-spin relaxation times at room temperature remain substantial challenges to practical spintronics. Here we report conduction electron spin-lattice and spin-spin relaxation times of 175 ns at 300 K in 37±7 nm carbon spheres, which is remarkably long for any conducting solid-state material of comparable size. Following the observation of spin polarization by electron spin resonance, we control the quantum state of the electron spin by applying short bursts of an oscillating magnetic field and observe coherent oscillations of the spin state. These results demonstrate the feasibility of operating electron spins in conducting carbon nanospheres as quantum bits at room temperature. PMID:27426851

  10. A highly reversible room-temperature lithium metal battery based on crosslinked hairy nanoparticles.

    PubMed

    Choudhury, Snehashis; Mangal, Rahul; Agrawal, Akanksha; Archer, Lynden A

    2015-01-01

    Rough electrodeposition, uncontrolled parasitic side-reactions with electrolytes and dendrite-induced short-circuits have hindered development of advanced energy storage technologies based on metallic lithium, sodium and aluminium electrodes. Solid polymer electrolytes and nanoparticle-polymer composites have shown promise as candidates to suppress lithium dendrite growth, but the challenge of simultaneously maintaining high mechanical strength and high ionic conductivity at room temperature has so far been unmet in these materials. Here we report a facile and scalable method of fabricating tough, freestanding membranes that combine the best attributes of solid polymers, nanocomposites and gel-polymer electrolytes. Hairy nanoparticles are employed as multifunctional nodes for polymer crosslinking, which produces mechanically robust membranes that are exceptionally effective in inhibiting dendrite growth in a lithium metal battery. The membranes are also reported to enable stable cycling of lithium batteries paired with conventional intercalating cathodes. Our findings appear to provide an important step towards room-temperature dendrite-free batteries. PMID:26634644

  11. Room temperature manipulation of long lifetime spins in metallic-like carbon nanospheres

    PubMed Central

    Náfrádi, Bálint; Choucair, Mohammad; Dinse, Klaus-Peter; Forró, László

    2016-01-01

    The time-window for processing electron spin information (spintronics) in solid-state quantum electronic devices is determined by the spin–lattice and spin–spin relaxation times of electrons. Minimizing the effects of spin–orbit coupling and the local magnetic contributions of neighbouring atoms on spin–lattice and spin–spin relaxation times at room temperature remain substantial challenges to practical spintronics. Here we report conduction electron spin–lattice and spin–spin relaxation times of 175 ns at 300 K in 37±7 nm carbon spheres, which is remarkably long for any conducting solid-state material of comparable size. Following the observation of spin polarization by electron spin resonance, we control the quantum state of the electron spin by applying short bursts of an oscillating magnetic field and observe coherent oscillations of the spin state. These results demonstrate the feasibility of operating electron spins in conducting carbon nanospheres as quantum bits at room temperature. PMID:27426851

  12. A highly reversible room-temperature lithium metal battery based on crosslinked hairy nanoparticles

    PubMed Central

    Choudhury, Snehashis; Mangal, Rahul; Agrawal, Akanksha; Archer, Lynden A.

    2015-01-01

    Rough electrodeposition, uncontrolled parasitic side-reactions with electrolytes and dendrite-induced short-circuits have hindered development of advanced energy storage technologies based on metallic lithium, sodium and aluminium electrodes. Solid polymer electrolytes and nanoparticle-polymer composites have shown promise as candidates to suppress lithium dendrite growth, but the challenge of simultaneously maintaining high mechanical strength and high ionic conductivity at room temperature has so far been unmet in these materials. Here we report a facile and scalable method of fabricating tough, freestanding membranes that combine the best attributes of solid polymers, nanocomposites and gel-polymer electrolytes. Hairy nanoparticles are employed as multifunctional nodes for polymer crosslinking, which produces mechanically robust membranes that are exceptionally effective in inhibiting dendrite growth in a lithium metal battery. The membranes are also reported to enable stable cycling of lithium batteries paired with conventional intercalating cathodes. Our findings appear to provide an important step towards room-temperature dendrite-free batteries. PMID:26634644

  13. Low cycle fatigue behavior of Zircaloy-2 at room temperature

    NASA Astrophysics Data System (ADS)

    Sudhakar Rao, G.; Chakravartty, J. K.; Nudurupati, Saibaba; Mahobia, G. S.; Chattopadhyay, Kausik; Santhi Srinivas, N. C.; Singh, Vakil

    2013-10-01

    Fuel cladding and pressure tubes of Zircaloy-2 in pressurized light and heavy water nuclear reactors experience plastic strain cycles due to power fluctuations in the reactor, such strain cycles cause low cycle fatigue (LCF) and could be life limiting factor for them. Factors like strain rate, strain amplitude and temperature are known to have marked influence on LCF behavior. The effect of strain rate from 10-2 to 10-4 s-1 on LCF behavior of Zircaloy-2 was studied, at different strain amplitudes between ±0.50% and ±1.25% at room temperature. Fatigue life was decreased with lowering of strain rate from 10-2 to 10-4 s-1 at all the strain amplitudes studied. While there was cyclic softening at lower strain amplitudes (Δεt/2 ⩽ ±0.60%) cyclic hardening was exhibited at higher strain amplitudes (Δεt/2 ⩾ ±1.00%) at all the strain rates. Further, there was secondary cyclic hardening during the later stage of cycling at all the strain amplitudes and the strain rates. Cyclic stress-strain hysteresis loops at the lowest strain rate of 10-4 s-1 were found to be heavily serrated, resulting from dynamic strain aging (DSA). There was significant effect of strain rate on dislocation substructure. The results are discussed in terms of high concentration of point defects generated during cyclic straining and their role in enhancing interaction between solutes and dislocations.

  14. Room-temperature chiral magnetic skyrmions in ultrathin magnetic nanostructures.

    PubMed

    Boulle, Olivier; Vogel, Jan; Yang, Hongxin; Pizzini, Stefania; de Souza Chaves, Dayane; Locatelli, Andrea; Menteş, Tevfik Onur; Sala, Alessandro; Buda-Prejbeanu, Liliana D; Klein, Olivier; Belmeguenai, Mohamed; Roussigné, Yves; Stashkevich, Andrey; Chérif, Salim Mourad; Aballe, Lucia; Foerster, Michael; Chshiev, Mairbek; Auffret, Stéphane; Miron, Ioan Mihai; Gaudin, Gilles

    2016-05-01

    Magnetic skyrmions are chiral spin structures with a whirling configuration. Their topological properties, nanometre size and the fact that they can be moved by small current densities have opened a new paradigm for the manipulation of magnetization at the nanoscale. Chiral skyrmion structures have so far been experimentally demonstrated only in bulk materials and in epitaxial ultrathin films, and under an external magnetic field or at low temperature. Here, we report on the observation of stable skyrmions in sputtered ultrathin Pt/Co/MgO nanostructures at room temperature and zero external magnetic field. We use high lateral resolution X-ray magnetic circular dichroism microscopy to image their chiral Néel internal structure, which we explain as due to the large strength of the Dzyaloshinskii-Moriya interaction as revealed by spin wave spectroscopy measurements. Our results are substantiated by micromagnetic simulations and numerical models, which allow the identification of the physical mechanisms governing the size and stability of the skyrmions. PMID:26809057

  15. Dielectric Behavior of Biomaterials at Different Frequencies on Room Temperature

    NASA Astrophysics Data System (ADS)

    Shrivastava, B. D.; Barde, Ravindra; Mishra, A.; Phadke, S.

    2014-09-01

    Propagation of electromagnetic (EM) waves in radiofrequency (RF) and microwave systems is described mathematically by Maxwell's equations with corresponding boundary conditions. Dielectric properties of lossless and lossy materials influence EM field distribution. For a better understanding of the physical processes associated with various RF and microwave devices, it is necessary to know the dielectric properties of media that interact with EM waves. For telecommunication and radar devices, variations of complex dielectric permittivity (referring to the dielectric property) over a wide frequency range are important. For RF and microwave applicators intended for thermal treatments of different materials at ISM (industrial, scientific, medical) frequencies, one needs to study temperature and moisture content dependencies of the Permittivity of the treated materials. Many techniques have been developed for the measurement of materials. In the present paper authors used Bones and scales of Fish taken from Narmada River (Rajghat Dist. Barwani) as biomaterials. Dielectric properties of Biomaterials with the frequency range from 1Hz to 10 MHz at room temperature with low water content were measured by in-situ performance dielectric kit. Analysis has been done by Alpha high performance impedance analyzer and LCR meters. The experimental work were carried out in Inter University Consortium UGC-DAE, CSR center Indore MP. Measured value indicates the dielectric constant (ɛ') dielectric loss (ɛ") decreases with increasing frequency while conductivity (σ) increases with frequency increased.

  16. Room-temperature ballistic transport in III-nitride heterostructures.

    PubMed

    Matioli, Elison; Palacios, Tomás

    2015-02-11

    Room-temperature (RT) ballistic transport of electrons is experimentally observed and theoretically investigated in III-nitrides. This has been largely investigated at low temperatures in low band gap III-V materials due to their high electron mobilities. However, their application to RT ballistic devices is limited by their low optical phonon energies, close to KT at 300 K. In addition, the short electron mean-free-path at RT requires nanoscale devices for which surface effects are a limitation in these materials. We explore the unique properties of wide band-gap III-nitride semiconductors to demonstrate RT ballistic devices. A theoretical model is proposed to corroborate experimentally their optical phonon energy of 92 meV, which is ∼4× larger than in other III-V semiconductors. This allows RT ballistic devices operating at larger voltages and currents. An additional model is described to determine experimentally a characteristic dimension for ballistic transport of 188 nm. Another remarkable property is their short carrier depletion at device sidewalls, down to 13 nm, which allows top-down nanofabrication of very narrow ballistic devices. These results open a wealth of new systems and basic transport studies possible at RT. PMID:25614931

  17. Engineering Room-temperature Superconductors Via ab-initio Calculations

    NASA Astrophysics Data System (ADS)

    Gulian, Mamikon; Melkonyan, Gurgen; Gulian, Armen

    The BCS, or bosonic model of superconductivity, as Little and Ginzburg have first argued, can bring in superconductivity at room temperatures in the case of high-enough frequency of bosonic mode. It was further elucidated by Kirzhnitset al., that the condition for existence of high-temperature superconductivity is closely related to negative values of the real part of the dielectric function at finite values of the reciprocal lattice vectors. In view of these findings, the task is to calculate the dielectric function for real materials. Then the poles of this function will indicate the existence of bosonic excitations which can serve as a "glue" for Cooper pairing, and if the frequency is high enough, and the dielectric matrix is simultaneously negative, this material is a good candidate for very high-Tc superconductivity. Thus, our approach is to elaborate a methodology of ab-initio calculation of the dielectric function of various materials, and then point out appropriate candidates. We used the powerful codes (TDDF with the DP package in conjunction with ABINIT) for computing dielectric responses at finite values of the wave vectors in the reciprocal lattice space. Though our report is concerned with the particular problem of superconductivity, the application range of the data processing methodology is much wider. The ability to compute the dielectric function of existing and still non-existing (though being predicted!) materials will have many more repercussions not only in fundamental sciences but also in technology and industry.

  18. Silicene field-effect transistors operating at room temperature

    NASA Astrophysics Data System (ADS)

    Tao, Li; Cinquanta, Eugenio; Chiappe, Daniele; Grazianetti, Carlo; Fanciulli, Marco; Dubey, Madan; Molle, Alessandro; Akinwande, Deji

    2015-03-01

    Free-standing silicene, a silicon analogue of graphene, has a buckled honeycomb lattice and, because of its Dirac bandstructure combined with its sensitive surface, offers the potential for a widely tunable two-dimensional monolayer, where external fields and interface interactions can be exploited to influence fundamental properties such as bandgap and band character for future nanoelectronic devices. The quantum spin Hall effect, chiral superconductivity, giant magnetoresistance and various exotic field-dependent states have been predicted in monolayer silicene. Despite recent progress regarding the epitaxial synthesis of silicene and investigation of its electronic properties, to date there has been no report of experimental silicene devices because of its air stability issue. Here, we report a silicene field-effect transistor, corroborating theoretical expectations regarding its ambipolar Dirac charge transport, with a measured room-temperature mobility of ˜100 cm2 V-1 s-1 attributed to acoustic phonon-limited transport and grain boundary scattering. These results are enabled by a growth-transfer-fabrication process that we have devised—silicene encapsulated delamination with native electrodes. This approach addresses a major challenge for material preservation of silicene during transfer and device fabrication and is applicable to other air-sensitive two-dimensional materials such as germanene and phosphorene. Silicene's allotropic affinity with bulk silicon and its low-temperature synthesis compared with graphene or alternative two-dimensional semiconductors suggest a more direct integration with ubiquitous semiconductor technology.

  19. Investigation of Room temperature Ferromagnetism in Mn doped Ge

    NASA Astrophysics Data System (ADS)

    Colakerol Arslan, Leyla; Toydemir, Burcu; Onel, Aykut Can; Ertas, Merve; Doganay, Hatice; Gebze Inst of Tech Collaboration; Research Center Julich Collaboration

    2014-03-01

    We present a systematic investigation of structural, magnetic and electronic properties of MnxGe1 -x single crystals. MnxGe1-x films were grown by sequential deposition of Ge and Mn by molecular-beam epitaxy at low substrate temperatures in order to avoid precipitation of ferromagnetic Ge-Mn intermetallic compounds. Reflected high energy electron diffraction and x-ray diffraction observations revealed that films are epitaxially grown on Si (001) substrates from the initial stage without any other phase formation. Magnetic measurements carried out using a physical property measurement system showed that all samples exhibited ferromagnetism at room temperature. Electron spin resonance indicates the presence of magnetically ordered localized spins of divalent Mn ions. X-ray absorption measurements at the Mn L-edge confirm significant substitutional doping of Mn into Ge-sites. The ferromagnetism was mainly induced by Mn substitution for Ge site, and indirect exchange interaction of these magnetic ions with the intrinsic charge carriers is the origin of ferromagnetism. The magnetic interactions were better understood by codoping with nonmagnetic impurities. This work was supported by Marie-Curie Reintegration Grant (PIRG08-GA-2010-276973).

  20. New Flexible Channels for Room Temperature Tunneling Field Effect Transistors

    PubMed Central

    Hao, Boyi; Asthana, Anjana; Hazaveh, Paniz Khanmohammadi; Bergstrom, Paul L.; Banyai, Douglas; Savaikar, Madhusudan A.; Jaszczak, John A.; Yap, Yoke Khin

    2016-01-01

    Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized boron nitride nanotubes (QDs-BNNTs) can be used as the flexible tunneling channels of TFETs at room temperatures. The electrical insulating BNNTs are used as the one-dimensional (1D) substrates to confine the uniform formation of Fe QDs on their surface as the flexible tunneling channel. Consistent semiconductor-like transport behaviors under various bending conditions are detected by scanning tunneling spectroscopy in a transmission electron microscopy system (in-situ STM-TEM). As suggested by computer simulation, the uniform distribution of Fe QDs enable an averaging effect on the possible electron tunneling pathways, which is responsible for the consistent transport properties that are not sensitive to bending. PMID:26846587

  1. New Flexible Channels for Room Temperature Tunneling Field Effect Transistors

    DOE PAGESBeta

    Hao, Boyi; Asthana, Anjana; Hazaveh, Paniz Khanmohammadi; Bergstrom, Paul L.; Banyai, Douglas; Savaikar, Madhusudan A.; Jaszczak, John A.; Yap, Yoke Khin

    2016-02-05

    Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized boron nitride nanotubes (QDs-BNNTs) can be used as the flexible tunneling channels of TFETs at room temperatures. The electrical insulating BNNTs are used as the one-dimensional (1D) substrates to confine the uniform formation of Fe QDs on their surface as the flexible tunneling channel. Consistent semiconductor-like transport behaviors under variousmore » bending conditions are detected by scanning tunneling spectroscopy in a transmission electron microscopy system (insitu STM-TEM). Ultimately, as suggested by computer simulation, the uniform distribution of Fe QDs enable an averaging effect on the possible electron tunneling pathways, which is responsible for the consistent transport properties that are not sensitive to bending.« less

  2. Electrodrift purification of materials for room temperature radiation detectors

    DOEpatents

    James, Ralph B.; Van Scyoc, III, John M.; Schlesinger, Tuviah E.

    1997-06-24

    A method of purifying nonmetallic, crystalline semiconducting materials useful for room temperature radiation detecting devices by applying an electric field across the material. The present invention discloses a simple technology for producing purified ionic semiconducting materials, in particular PbI.sub.2 and preferably HgI.sub.2, which produces high yields of purified product, requires minimal handling of the material thereby reducing the possibility of introducing or reintroducing impurities into the material, is easy to control, is highly selective for impurities, retains the stoichiometry of the material and employs neither high temperatures nor hazardous materials such as solvents or liquid metals. An electric field is applied to a bulk sample of the material causing impurities present in the sample to drift in a preferred direction. After all of the impurities have been transported to the ends of the sample the current flowing through the sample, a measure of the rate of transport of mobile impurities, falls to a low, steady state value, at which time the end sections of the sample where the impurities have concentrated are removed leaving a bulk sample of higher purity material. Because the method disclosed here only acts on the electrically active impurities, the stoichiometry of the host material remains substantially unaffected.

  3. A computed room temperature line list for phosphine

    NASA Astrophysics Data System (ADS)

    Sousa-Silva, Clara; Yurchenko, Sergei N.; Tennyson, Jonathan

    2013-06-01

    An accurate and comprehensive room temperature rotation-vibration transition line list for phosphine (31PH3) is computed using a newly refined potential energy surface and a previously constructed ab initio electric dipole moment surface. Energy levels, Einstein A coefficients and transition intensities are computed using these surfaces and a variational approach to the nuclear motion problem as implemented in the program TROVE. A ro-vibrational spectrum is computed, covering the wavenumber range 0-8000 cm-1. The resulting line list, which is appropriate for temperatures up to 300 K, consists of a total of 137 million transitions between 5.6 million energy levels. Several of the band centres are shifted to better match experimental transition frequencies. The line list is compared to the most recent HITRAN database and other laboratorial sources. Transition wavelengths and intensities are generally found to be in good agreement with the existing experimental data, with particularly close agreement for the rotational spectrum. An analysis of the comparison between the theoretical data created and the existing experimental data is performed, and suggestions for future improvements and assignments to the HITRAN database are made.

  4. New Flexible Channels for Room Temperature Tunneling Field Effect Transistors.

    PubMed

    Hao, Boyi; Asthana, Anjana; Hazaveh, Paniz Khanmohammadi; Bergstrom, Paul L; Banyai, Douglas; Savaikar, Madhusudan A; Jaszczak, John A; Yap, Yoke Khin

    2016-01-01

    Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized boron nitride nanotubes (QDs-BNNTs) can be used as the flexible tunneling channels of TFETs at room temperatures. The electrical insulating BNNTs are used as the one-dimensional (1D) substrates to confine the uniform formation of Fe QDs on their surface as the flexible tunneling channel. Consistent semiconductor-like transport behaviors under various bending conditions are detected by scanning tunneling spectroscopy in a transmission electron microscopy system (in-situ STM-TEM). As suggested by computer simulation, the uniform distribution of Fe QDs enable an averaging effect on the possible electron tunneling pathways, which is responsible for the consistent transport properties that are not sensitive to bending. PMID:26846587

  5. MTR, TRA603. BASEMENT DECONTAMINATION ROOM DETAILS. WALLS OF SOLID CONCRETE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    MTR, TRA-603. BASEMENT DECONTAMINATION ROOM DETAILS. WALLS OF SOLID CONCRETE MASONRY. STAINLESS STEEL WORK BENCH, FLOOR COVING AND DRAINS. "WARM" FLOOR DRAIN. OVERHEAD SHOWER WITH CHAIN PULL. IDO MTR-603-IDO-4, 12/1952. INL INDEX NO. 531-0603-00-396-110468, REV. 1. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  6. Room-temperature ferromagnetic behaviour of InMnAs films grown by laser ablation technique

    NASA Astrophysics Data System (ADS)

    Danilov, Yury; Drozdov, Yury; Kudrin, Alexey; Vikhrova, Olga; Zvonkov, Boris; Sapozhnikov, Maxim; Fetisov, Leonid; Semisalova, Anna; Perov, Nikolai

    2010-01-01

    InMnAs layers were fabricated by pulsed laser ablation of solid targets (Mn and InAs) in flow of hydrogen and arsine. The InMnAs layers with thickness ranging from 130 to 270 nm were deposited on semi-insulating GaAs (100) substrates at 320°C. The Mn quantity was controlled by changing ratio of sputtering time of Mn and InAs targets. The X-ray diffraction measurements identified the InMnAs as mosaic monocrystal with MnAs phase texture inclusions. Room temperature ferromagnetism of these InMnAs layers is evident from magnetometry and magneto-optical measurements. In addition, the InMnAs layers show anomalous Hall effect with the hysteresis loop and saturation magnetic field HS ≈ 2500 Oe at temperatures up to 300K depending on the Mn content. The Curie temperature higher than 300K allows using these magnetic semiconductor layers as a source of spin polarized carriers in room temperature spintronic devices.

  7. Room-temperature ferromagnetic behaviour of InMnAs films grown by laser ablation technique

    NASA Astrophysics Data System (ADS)

    Yury, Danilov; Yury, Drozdov; Alexey, Kudrin; Olga, Vikhrova; Boris, Zvonkov; Maxim, Sapozhnikov; Leonid, Fetisov; Anna, Semisalova; Nikolai, Perov

    2010-01-01

    InMnAs layers were fabricated by pulsed laser ablation of solid targets (Mn and InAs) in flow of hydrogen and arsine. The InMnAs layers with thickness ranging from 130 to 270 nm were deposited on semi-insulating GaAs (100) substrates at 320°C. The Mn quantity was controlled by changing ratio of sputtering time of Mn and InAs targets. The X-ray diffraction measurements identified the InMnAs as mosaic monocrystal with MnAs phase texture inclusions. Room temperature ferromagnetism of these InMnAs layers is evident from magnetometry and magneto-optical measurements. In addition, the InMnAs layers show anomalous Hall effect with the hysteresis loop and saturation magnetic field HS approx 2500 Oe at temperatures up to 300K depending on the Mn content. The Curie temperature higher than 300K allows using these magnetic semiconductor layers as a source of spin polarized carriers in room temperature spintronic devices.

  8. Reversible oxygen scavenging at room temperature using electrochemically reduced titanium oxide nanotubes

    NASA Astrophysics Data System (ADS)

    Close, Thomas; Tulsyan, Gaurav; Diaz, Carlos A.; Weinstein, Steven J.; Richter, Christiaan

    2015-05-01

    A material capable of rapid, reversible molecular oxygen uptake at room temperature is desirable for gas separation and sensing, for technologies that require oxygen storage and oxygen splitting such as fuel cells (solid-oxide fuel cells in particular) and for catalytic applications that require reduced oxygen species (such as removal of organic pollutants in water and oil-spill remediation). To date, however, the lowest reported temperature for a reversible oxygen uptake material is in the range of 200-300 °C, achieved in the transition metal oxides SrCoOx (ref. 1) and LuFe2O4+x (ref. 2) via thermal cycling. Here, we report rapid and reversible oxygen scavenging by TiO2-x nanotubes at room temperature. The uptake and release of oxygen is accomplished by an electrochemical rather than a standard thermal approach. We measure an oxygen uptake rate as high as 14 mmol O2 g-1 min-1, ˜2,400 times greater than commercial, irreversible oxygen scavengers. Such a fast oxygen uptake at a remarkably low temperature suggests a non-typical mechanistic pathway for the re-oxidation of TiO2-x. Modelling the diffusion of oxygen, we show that a likely pathway involves ‘exceptionally mobile’ interstitial oxygen produced by the oxygen adsorption and decomposition dynamics, recently observed on the surface of anatase.

  9. AW-101 entrained solids - Solubility versus temperature

    SciTech Connect

    GJ Lumetta; RC Lettau; GF Piepel

    2000-03-31

    This report describes the results of a test conducted by Battelle to assess the solubility of the solids entrained in the diluted AW-101 low-activity waste (LAW) sample. BNFL requested Battelle to dilute the AW-1-1 sample using de-ionized water to mimic expected plant operating conditions. BNFL further requested Battelle to assess the solubility of the solids present in the diluted AW-101 sample versus temperature conditions of 30, 40, and 50 C. BNFL requested these tests to assess the composition of the LAW supernatant and solids versus expected plant-operating conditions. The work was conducted according to test plan BNFL-TP-29953-7, Rev. 0, Determination of the Solubility of LAW Entrained Solids. The test went according to plan, with no deviations from the test plan.

  10. Effect of Temperature Cycling and Exposure to Extreme Temperatures on Reliability of Solid Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2007-01-01

    In this work, results of multiple temperature cycling (TC) (up to 1,000 cycles) of different types of solid tantalum capacitors are analyzed and reported. Deformation of chip tantalum during temperature variations simulating reflow soldering conditions was measured to evaluate the possibility of the pop-corning effect in the parts. To simulate the effect of short-time exposures to solder reflow temperatures on the reliability of tantalum capacitors, several part types were subjected to multiple cycles (up to 100) between room temperature and 240 C with periodical measurements of electrical characteristics of the parts. Mechanisms of degradation caused by temperature cycling and exposure to high temperatures, and the requirements of MIL-PRF-55365 for assessment of the resistance of the parts to soldering heat are discussed.

  11. Room Temperature Solvent-free Synthesis of Monodisperse Magnetite Nanocrystals

    SciTech Connect

    Ye, Xiang-Rong; Daraio, C; Wang, Chong M.; Talbot, J; Jin, Sungho

    2006-03-01

    We have successfully demonstrated a facile, solvent-free synthesis of highly crystalline and monodisperse Fe3O4 nanocrystallites at ambient temperature avoiding any heating. Solid state reaction of inorganic Fe(II) and Fe(III) salts with NaOH was found to produce highly crystalline Fe3O4 nanoparticles. The reaction, if carried out in the presence of surfactant such as oleic acid-oleylamine adduct, generated monodisperse Fe3O4 nanocrystals extractable directly from the reaction mixture. The extracted nanoparticles were capable of forming self-assembled, two-dimensional and uniform periodic array. The new process utilizes inexpensive and nontoxic starting materials, and does not require a use of high boiling point and toxic solvents, thus is amenable to an environmentally desirable, large-scale synthesis of nanocrystals.

  12. Quasi-Solid Electrolytes for High Temperature Lithium Ion Batteries.

    PubMed

    Kalaga, Kaushik; Rodrigues, Marco-Tulio F; Gullapalli, Hemtej; Babu, Ganguli; Arava, Leela Mohana Reddy; Ajayan, Pulickel M

    2015-11-25

    Rechargeable batteries capable of operating at high temperatures have significant use in various targeted applications. Expanding the thermal stability of current lithium ion batteries requires replacing the electrolyte and separators with stable alternatives. Since solid-state electrolytes do not have a good electrode interface, we report here the development of a new class of quasi-solid-state electrolytes, which have the structural stability of a solid and the wettability of a liquid. Microflakes of clay particles drenched in a solution of lithiated room temperature ionic liquid forming a quasi-solid system has been demonstrated to have structural stability until 355 °C. With an ionic conductivity of ∼3.35 mS cm(-1), the composite electrolyte has been shown to deliver stable electrochemical performance at 120 °C, and a rechargeable lithium battery with Li4Ti5O12 electrode has been tested to deliver reliable capacity for over several cycles of charge-discharge. PMID:26535786

  13. Photochromism and Photomagnetism of a 3d-4f Hexacyanoferrate at Room Temperature.

    PubMed

    Cai, Li-Zhen; Chen, Qing-Song; Zhang, Cui-Juan; Li, Pei-Xin; Wang, Ming-Sheng; Guo, Guo-Cong

    2015-09-01

    Polycyanometallate compounds with both photochromism and photomagnetism have appealing applications in optical switches and memories, but such optical behaviors were essentially restricted to the cryogenic temperature. We realized, for the first time, the photochromism and photomagnetism of 3d-4f hexacyanoferrates at room temperature (RT) in [Eu(III)(18C6)(H2O)3]Fe(III)(CN)6·2H2O (18C6 = 18-crown-6). Photoinduced electron transfer (PET) from crown to Fe(III) yields long-lived charge-separated species at RT in air in the solid state and also weakens the magnetic susceptibility significantly. The PET mechanism and changing trend of photomagnetism differ significantly from those reported for known 3d-4f hexacyanoferrates. This work not only develops a new type of inorganic-organic hybrid photochromic material but opens a new avenue for RT photomagnetic polycyanometallate compounds. PMID:26284651

  14. New layered metal oxides as positive electrode materials for room-temperature sodium-ion batteries

    NASA Astrophysics Data System (ADS)

    Mu, Lin-Qin; Hu, Yong-Sheng; Chen, Li-Quan

    2015-03-01

    In order to achieve better Na storage performance, most layered oxide positive electrode materials contain toxic and expensive transition metals Ni and/or Co, which are also widely used for lithium-ion batteries. Here we report a new quaternary layered oxide consisting of Cu, Fe, Mn, and Ti transition metals with O3-type oxygen stacking as a positive electrode for room-temperature sodium-ion batteries. The material can be simply prepared by a high-temperature solid-state reaction route and delivers a reversible capacity of 94 mAh/g with an average storage voltage of 3.2 V. This paves the way for cheaper and non-toxic batteries with high Na storage performance. Project supported by the National Natural Science Foundation of China (Grant Nos. 51222210 and 11234013) and the One Hundred Talent Project of the Chinese Academy of Sciences.

  15. Non-magnetic organic/inorganic spin injector at room temperature

    SciTech Connect

    Mathew, Shinto P.; Mondal, Prakash Chandra; Naaman, Ron; Moshe, Hagay; Mastai, Yitzhak

    2014-12-15

    Spin injection into solid-state devices is commonly performed by use of ferromagnetic metal electrodes. Here, we present a spin injector design without permanent magnet; rather, the spin selectivity is determined by a chiral tunneling barrier. The chiral tunneling barrier is composed of an ultrathin Al{sub 2}O{sub 3} layer that is deposited on top of a chiral self-assembled monolayer (SAM), which consists of cysteine or oligopeptide molecules. The experimentally observed magnetoresistance can be up to 20% at room temperature, and it displays an uncommon asymmetric curve as a function of the applied magnetic field. These findings show that the spin injector transmits only one spin orientation, independent of external magnetic field. The sign of the magnetoresistance depends on the handedness of the molecules in the SAM, which act as a spin filter, and the magnitude of the magnetoresistance depends only weakly on temperature.

  16. Gradient Limitations in Room Temperature and Superconducting Acceleration Structures

    SciTech Connect

    Solyak, N. A.

    2009-01-22

    Accelerating gradient is a key parameter of the accelerating structure in large linac facilities, like future Linear Collider. In room temperature accelerating structures the gradient is limited mostly by breakdown phenomena, caused by high surface electric fields or pulse surface heating. High power processing is a necessary procedure to clean surface and improve the gradient. In the best tested X-band structures the achieved gradient is exceed 100 MV/m in of {approx}200 ns pulses for breakdown rate of {approx}10{sup -7}. Gradient limit depends on number of factors and no one theory which can explain all sets of experimental results and predict gradient in new accelerating structure. In paper we briefly overview the recent experimental results of breakdown studies, progress in understanding of gradient limitations and scaling laws. Although superconducting rf technology has been adopted throughout the world for ILC, it has frequently been difficult to reach the predicted performance in these structures due to a number of factors: multipactoring, field emission, Q-slope, thermal breakdown. In paper we are discussing all these phenomena and the ways to increase accelerating gradient in SC cavity, which are a part of worldwide R and D program.

  17. Room-temperature terahertz detection based on CVD graphene transistor

    NASA Astrophysics Data System (ADS)

    Yang, Xin-Xin; Sun, Jian-Dong; Qin, Hua; Lv, Li; Su, Li-Na; Yan, Bo; Li, Xin-Xing; Zhang, Zhi-Peng; Fang, Jing-Yue

    2015-04-01

    We report the fabrication and characterization of a single-layer graphene field-effect terahertz detector, which is coupled with dipole-like antennas based on the self-mixing detector model. The graphene is grown by chemical vapor deposition and then transferred onto an SiO2/Si substrate. We demonstrate room-temperature detection at 237 GHz. The detector could offer a voltage responsivity of 0.1 V/W and a noise equivalent power of 207 nW/Hz1/2. Our modeling indicates that the observed photovoltage in the p-type gated channel can be well fit by the self-mixing theory. A different photoresponse other than self-mixing may apply for the n-type gated channel. Project supported by the National Natural Science Foundation of China (Grant Nos. 61271157, 61401456, and 11403084), Jiangsu Provincial Planned Projects for Postdoctoral Research Funds (Grant No. 1301054B), the Fund from Suzhou Industry Technology Bureau (Grant No. ZXG2012024), China Postdoctoral Science Foundation (Grant No. 2014M551678), the Graduate Student Innovation Program for Universities of Jiangsu Province (Grant No. CXLX12_0724), the Fundamental Research Funds for the Central Universities (Grant No. JUDCF 12032), and the Fund from National University of Defense Technology (Grant No. JC13-02-14).

  18. Above-room-temperature ferroelectricity and antiferroelectricity in benzimidazoles

    PubMed Central

    Horiuchi, Sachio; Kagawa, Fumitaka; Hatahara, Kensuke; Kobayashi, Kensuke; Kumai, Reiji; Murakami, Youichi; Tokura, Yoshinori

    2012-01-01

    The imidazole unit is chemically stable and ubiquitous in biological systems; its proton donor and acceptor moieties easily bind molecules into a dipolar chain. Here we demonstrate that chains of these amphoteric molecules can often be bistable in electric polarity and electrically switchable, even in the crystalline state, through proton tautomerization. Polarization–electric field (P–E) hysteresis experiments reveal a high electric polarization ranging from 5 to 10 μC cm−2 at room temperature. Of these molecules, 2-methylbenzimidazole allows ferroelectric switching in two dimensions due to its pseudo-tetragonal crystal symmetry. The ferroelectricity is also thermally robust up to 400 K, as is that of 5,6-dichloro-2-methylbenzimidazole (up to ~373 K). In contrast, three other benzimidazoles exhibit double P–E hysteresis curves characteristic of antiferroelectricity. The diversity of imidazole substituents is likely to stimulate a systematic exploration of various structure–property relationships and domain engineering in the quest for lead- and rare-metal-free ferroelectric devices. PMID:23250438

  19. A silicon carbide room-temperature single-photon source.

    PubMed

    Castelletto, S; Johnson, B C; Ivády, V; Stavrias, N; Umeda, T; Gali, A; Ohshima, T

    2014-02-01

    Over the past few years, single-photon generation has been realized in numerous systems: single molecules, quantum dots, diamond colour centres and others. The generation and detection of single photons play a central role in the experimental foundation of quantum mechanics and measurement theory. An efficient and high-quality single-photon source is needed to implement quantum key distribution, quantum repeaters and photonic quantum information processing. Here we report the identification and formation of ultrabright, room-temperature, photostable single-photon sources in a device-friendly material, silicon carbide (SiC). The source is composed of an intrinsic defect, known as the carbon antisite-vacancy pair, created by carefully optimized electron irradiation and annealing of ultrapure SiC. An extreme brightness (2×10(6) counts s(-1)) resulting from polarization rules and a high quantum efficiency is obtained in the bulk without resorting to the use of a cavity or plasmonic structure. This may benefit future integrated quantum photonic devices. PMID:24240243

  20. Gradient limitations in room temperature and superconducting acceleration structures

    SciTech Connect

    Solyak, N.A.; /Fermilab

    2008-10-01

    Accelerating gradient is a key parameter of the accelerating structure in large linac facilities, like future Linear Collider. In room temperature accelerating structures the gradient is limited mostly by breakdown phenomena, caused by high surface electric fields or pulse surface heating. High power processing is a necessary procedure to clean surface and improve the gradient. In the best tested X-band structures the achieved gradient is exceed 100 MV/m in of {approx}200 ns pulses for breakdown rate of {approx} 10{sup -7}. Gradient limit depends on number of factors and no one theory which can explain all sets of experimental results and predict gradient in new accelerating structure. In paper we briefly overview the recent experimental results of breakdown studies, progress in understanding of gradient limitations and scaling laws. Although superconducting rf technology has been adopted throughout the world for ILC, it has frequently been difficult to reach the predicted performance in these structures due to a number of factors: multipactoring, field emission, Q-slope, thermal breakdown. In paper we are discussing all these phenomena and the ways to increase accelerating gradient in SC cavity, which are a part of worldwide R&D program.

  1. Spontaneous Boron-doping of Graphene at Room Temperature

    NASA Astrophysics Data System (ADS)

    Pan, Lida; Que, Yande; Du, Shixuan; Gao, Hongjun; Pantelides, Sokrates T.

    2015-03-01

    Doping graphene with boron or nitrogen is an effective way to modify its electronic properties. However, the reaction barrier for introducing these impurities is quite high, making the doping process difficult. In this work, we propose a low-energy reaction route derived from first-principles calculations and subsequently validated by experiments. The calculations show that, when graphene is placed on a ruthenium substrate and exposed to atomic boron, boron atoms can incorporate substitutionally into the graphene sheet with an energy barrier about 0.1 eV, displacing carbon atoms below the graphene sheet where they migrates away. This result suggests that spontaneous doping by boron can take place at room temperature. Following the prediction, we grew high-quality graphene on the Ru(0001) surface and then expose it to B2H6 which decomposes into atomic boron. XPS and STM results indicate that boron dopes graphene substantially without disturbing the graphene lattice, confirming the theoretical predictions. Doping by nitrogen and co-doping by B and N will also be discussed.

  2. Insulating room temperature ferromagnetic SrTiO3

    NASA Astrophysics Data System (ADS)

    Posadas, Agham; Mitra, Chandrima; Lin, Chungwei; Dhamdere, Ajit; Smith, David; Tsoi, Maxim; Demkov, Alex

    2013-03-01

    We report the epitaxial growth of ferromagnetic insulating material based on SrTiO3 using molecular beam epitaxy (MBE). SrTi1-xCoxO3-δ films (x = 0.1 to 0.5) were grown on Si(100) substrates via a buffer layer of four unit cells of undoped SrTiO3. The crystalline structure was characterized by reflection high energy electron diffraction, x-ray diffraction, and cross-section transmission electron microscopy. Robust room-temperature ferromagnetism is confirmed in samples with composition 30-40% Co. We also performed in situx-ray photoelectron spectroscopy of the Sr, Co, Ti, and O core levels to determine stoichiometry and cobalt oxidation state. In all single phase samples, an oxygen vacancy concentration of approximately equal to the amount of Co substitution was measured (compensated doping). In order to elucidate the origin of ferromagnetism, we also performed first-principles calculations of SrTiO3 simultaneously doped with Co and an oxygen vacancy. We find that such a configuration at concentrations of ~ 25% can result in a ferromagnetic insulating state with high spin Co2+. The ability to integrate an insulating ferromagnet on silicon in epitaxial form may potentially be useful for spin filtering and spin wave applications in the field of spintronics.

  3. Surface activation-based nanobonding and interconnection at room temperature

    NASA Astrophysics Data System (ADS)

    Howlader, M. M. R.; Yamauchi, A.; Suga, T.

    2011-02-01

    Flip chip nanobonding and interconnect system (NBIS) equipment with high precision alignment has been developed based on the surface activated bonding method for high-density interconnection and MEMS packaging. The 3σ alignment accuracy in the IR transmission system was approximately ±0.2 µm. The performance of the NBIS has been preliminarily investigated through bonding between relatively rough surfaces of copper through silicon vias (Cu-TSVs) and gold-stud bumps (Au-SBs), and smooth surfaces of silicon wafers. The Cu-TSVs of 55 µm diameter and the Au-SBs of 35 µm diameter with ~6-10 nm surface roughness (RMS) were bonded at room temperature after surface activation using an argon fast atom beam (Ar-FAB) under 0.16 N per bump. Silicon wafers of 50 mm diameter with ~0.2 nm RMS surface roughness were bonded without heating after surface activation. Void-free interfaces both in Cu-TSV/Au-SB and silicon/silicon with bonding strength equivalent to bulk fracture of Au and silicon, respectively, were achieved. A few nm thick amorphous layers were observed across the silicon/silicon interface that was fabricated by the Ar-FAB. This study in the interconnection and bonding facilitates the required three-dimensional integration on the same surface for high-density electronic and biomedical systems.

  4. Room-temperature luminescence from kaolin induced by organic amines

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Kloepping, R.; Pollack, G.

    1984-01-01

    Several new, room-temperature luminescent phenomena, resulting from the interaction of kaolin and various amino compounds, have been observed. The emission of light from kaolin pastes (treated with quinoline, pyridine, hydrazine, monoethanolamine, n-butylamine, and piperidine) was shown to decay monotonically over a period of hours to days. More light was released by a given amino compound after it was dried and purified. Hydrazine, in addition to the monotonically decaying photon release, produces delayed pulses of light with peak emission wavelength of 365 nm which last between several hours and several days. These photon bursts are acutely sensitive to the initial dryness of the hydrazine, both in the number of bursts and the integrated photon output. The amount of light and the capacity of the kaolin to produce the delayed burst appeared to be strongly dependent on preliminary heating and on gamma-irradiation, analogous to the dehydration-induced light pulse previously reported from the Ames Research Center. A small, delayed burst of photons occurred when piperidine and n-butylamine were removed by evaporation into an H2SO4 reservoir.

  5. Realization of Ground State Artificial Skyrmion Lattices at Room Temperature

    NASA Astrophysics Data System (ADS)

    Gilbert, Dustin A.; Maranville, Brian B.; Balk, Andrew J.; Kirby, Brian J.; Pierce, Daniel T.; Unguris, John; Borchers, Julie A.; Fischer, Peter; Liu, Kai

    Artificial skyrmion lattices stable at ambient conditions offer a convenient and powerful platform to explore skyrmion physics and topological phenomena and motivates their inclusion in next-generation data and logic devices. In this work we present direct experimental evidence of artificial skyrmion lattices with a stable ground state at room temperature. Our approach is to pattern vortex-state Co nanodots (560 nm diameter) in hexagonal arrays on top of a Co/Pd multilayer with perpendicular magnetic anisotropy; the skyrmion state is prepared using a specific magnetic field sequence. Ion irradiation has been employed to suppress PMA in the underlayer and allow imprinting of the vortex structure from the nanodots to form skyrmion lattices, as revealed by polarized neutron reflectometry. Circularity control is realized through Co dot shape asymmetry, and confirmed by microscopy and FORC magnetometry. The vortex polarity is set during the field sequence and confirmed by magnetometry. Spin-transport studies further demonstrate a sensitivity to the skyrmion spin texture.Work supported by NSF (DMR-1008791, ECCS-1232275 and DMR-1543582)

  6. Water-driven structure transformation in nanoparticles at room temperature.

    PubMed

    Zhang, Hengzhong; Gilbert, Benjamin; Huang, Feng; Banfield, Jillian F

    2003-08-28

    The thermodynamic behaviour of small particles differs from that of the bulk material by the free energy term gammaA--the product of the surface (or interfacial) free energy and the surface (or interfacial) area. When the surfaces of polymorphs of the same material possess different interfacial free energies, a change in phase stability can occur with decreasing particle size. Here we describe a nanoparticle system that undergoes structural changes in response to changes in the surface environment rather than particle size. ZnS nanoparticles (average diameter 3 nm) were synthesized in methanol and found to exhibit a reversible structural transformation accompanying methanol desorption, indicating that the particles readily adopt minimum energy structural configurations. The binding of water to the as-formed particles at room temperature leads to a dramatic structural modification, significantly reducing distortions of the surface and interior to generate a structure close to that of sphalerite (tetrahedrally coordinated cubic ZnS). These findings suggest a route for post-synthesis control of nanoparticle structure and the potential use of the nanoparticle structural state as an environmental sensor. Furthermore, the results imply that the structure and reactivity of nanoparticles at planetary surfaces, in interplanetary dust and in the biosphere, will depend on both particle size and the nature of the surrounding molecules. PMID:12944961

  7. Proactive aquatic ecotoxicological assessment of room-temperature ionic liquids

    USGS Publications Warehouse

    Kulacki, K.J.; Chaloner, D.T.; Larson, J.H.; Costello, D.M.; Evans-White, M. A.; Docherty, K.M.; Bernot, R.J.; Brueseke, M.A.; Kulpa, C.F.; Lamberti, G.A.

    2011-01-01

    Aquatic environments are being contaminated with a myriad of anthropogenic chemicals, a problem likely to continue due to both unintentional and intentional releases. To protect valuable natural resources, novel chemicals should be shown to be environmentally safe prior to use and potential release into the environment. Such proactive assessment is currently being applied to room-temperature ionic liquids (ILs). Because most ILs are water-soluble, their effects are likely to manifest in aquatic ecosystems. Information on the impacts of ILs on numerous aquatic organisms, focused primarily on acute LC50 and EC50 endpoints, is now available, and trends in toxicity are emerging. Cation structure tends to influence IL toxicity more so than anion structure, and within a cation class, the length of alkyl chain substituents is positively correlated with toxicity. While the effects of ILs on several aquatic organisms have been studied, the challenge for aquatic toxicology is now to predict the effects of ILs in complex natural environments that often include diverse mixtures of organisms, abiotic conditions, and additional stressors. To make robust predictions about ILs will require coupling of ecologically realistic laboratory and field experiments with standard toxicity bioassays and models. Such assessments would likely discourage the development of especially toxic ILs while shifting focus to those that are more environmentally benign. Understanding the broader ecological effects of emerging chemicals, incorporating that information into predictive models, and conveying the conclusions to those who develop, regulate, and use those chemicals, should help avoid future environmental degradation. ?? 2011 Bentham Science Publishers Ltd.

  8. Giant single-molecule anisotropic magnetoresistance at room temperature.

    PubMed

    Li, Ji-Jun; Bai, Mei-Lin; Chen, Zhao-Bin; Zhou, Xiao-Shun; Shi, Zhan; Zhang, Meng; Ding, Song-Yuan; Hou, Shi-Min; Schwarzacher, Walther; Nichols, Richard J; Mao, Bing-Wei

    2015-05-13

    We report an electrochemically assisted jump-to-contact scanning tunneling microscopy (STM) break junction approach to create reproducible and well-defined single-molecule spintronic junctions. The STM break junction is equipped with an external magnetic field either parallel or perpendicular to the electron transport direction. The conductance of Fe-terephthalic acid (TPA)-Fe single-molecule junctions is measured and a giant single-molecule tunneling anisotropic magnetoresistance (T-AMR) up to 53% is observed at room temperature. Theoretical calculations based on first-principles quantum simulations show that the observed AMR of Fe-TPA-Fe junctions originates from electronic coupling at the TPA-Fe interfaces modified by the magnetic orientation of the Fe electrodes with respect to the direction of current flow. The present study highlights new opportunities for obtaining detailed understanding of mechanisms of charge and spin transport in molecular junctions and the role of interfaces in determining the MR of single-molecule junctions. PMID:25894840

  9. Cross-linking of polytetrafluoroethylene during room-temperature irradiation

    SciTech Connect

    Pugmire, David L; Wetteland, Chris J; Duncan, Wanda S; Lakis, Rollin E; Schwartz, Daniel S

    2008-01-01

    Exposure of polytetrafluoroethylene (PTFE) to {alpha}-radiation was investigated to detennine the physical and chemical effects, as well as to compare and contrast the damage mechanisms with other radiation types ({beta}, {gamma}, or thermal neutron). A number of techniques were used to investigate the chemical and physical changes in PTFE after exposure to {alpha}-radiation. These techniques include: Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and fluorescence spectroscopy. Similar to other radiation types at low doses, the primary damage mechanism for the exposure of PTFE to {alpha}-radiation appears to be chain scission. Increased doses result in a change-over of the damage mechanism to cross-linking. This result is not observed for any radiation type other than {alpha} when irradiation is performed at room temperature. Finally, at high doses, PTFE undergoes mass-loss (via smallfluorocarbon species evolution) and defluorination. The amount and type of damage versus sample depth was also investigated. Other types of radiation yield damage at depths on the order of mm to cm into PTFE due to low linear energy transfer (LET) and the correspondingly large penetration depths. By contrast, the {alpha}-radiation employed in this study was shown to only induce damage to a depth of approximately 26 {mu}m, except at very high doses.

  10. Microstructure of room temperature ionic liquids at stepped graphite electrodes

    DOE PAGESBeta

    Feng, Guang; Li, Song; Zhao, Wei; Cummings, Peter T.

    2015-07-14

    Molecular dynamics simulations of room temperature ionic liquid (RTIL) [emim][TFSI] at stepped graphite electrodes were performed to investigate the influence of the thickness of the electrode surface step on the microstructure of interfacial RTILs. A strong correlation was observed between the interfacial RTIL structure and the step thickness in electrode surface as well as the ion size. Specifically, when the step thickness is commensurate with ion size, the interfacial layering of cation/anion is more evident; whereas, the layering tends to be less defined when the step thickness is close to the half of ion size. Furthermore, two-dimensional microstructure of ionmore » layers exhibits different patterns and alignments of counter-ion/co-ion lattice at neutral and charged electrodes. As the cation/anion layering could impose considerable effects on ion diffusion, the detailed information of interfacial RTILs at stepped graphite presented here would help to understand the molecular mechanism of RTIL-electrode interfaces in supercapacitors.« less

  11. Controlled synthesis of pentagonal gold nanotubes at room temperature.

    PubMed

    Bi, Yingpu; Lu, Gongxuan

    2008-07-01

    Large quantities of pentagonal gold nanotubes have been synthesized by reducing chloroauric acid with silver nanowires in an aqueous solution of hexadecyltrimethylammonium bromide (CTAB) at room temperature. These gold nanotubes possess perfect structures, smooth surfaces, highly crystalline walls, and similar cross-sections to that of the silver template. In this process, the CTAB participation was found to be crucial for shape-controlled synthesis of pentagonal gold nanotubes. In the absence of CTAB, loose and hollow gold structures were routinely generated, while bundled gold nanotubes with rough surfaces were obtained by replacing the CTAB with poly(vinyl pyrrolidone) (PVP). The possible formation mechanism of pentagonal gold nanotubes has also been discussed on the basis of various growth stages studied by field-emission scanning electron microscopy (FE-SEM) images. In addition, the catalytic properties of these hollow nanostructures for hydrogen generation reaction from HCHO solution have also been investigated. They showed higher activity than that of spherical gold nanoparticles. PMID:21828702

  12. Manganese perovskites for room temperature magnetic refrigeration applications

    NASA Astrophysics Data System (ADS)

    Phan, Manh-Huong; Peng, Hua-Xin; Yu, Seong-Cho; Tho, Nguyen Duc; Nhat, Hoang Nam; Chau, Nguyen

    2007-09-01

    We found the large magnetocaloric effect (MCE) in La 0.6Ca 0.3Pb 0.1MnO 3 (sample No. 1), La 0.7Ca 0.2Pb 0.1MnO 3 (sample No. 2), and La 0.7Ca 0.1Pb 0.2MnO 3 (sample No. 3) perovskites, which were prepared by a conventional ceramic method. For a magnetic field change of 13.5 kOe, the magnetic entropy change (Δ SM) reached values of 2.55, 2.53 and 3.72 J/kg K for samples Nos. 1, 2 and 3, respectively. Interestingly, the large Δ SM was found to occur around 300 K for all samples investigated, which allows magnetic refrigeration at room temperature. These perovskites have the large magnetic entropy changes induced by low magnetic field change, which is beneficial for the household application of active magnetic refrigerant (AMR) materials.

  13. Above-room-temperature ferroelectricity and antiferroelectricity in benzimidazoles

    NASA Astrophysics Data System (ADS)

    Horiuchi, Sachio; Kagawa, Fumitaka; Hatahara, Kensuke; Kobayashi, Kensuke; Kumai, Reiji; Murakami, Youichi; Tokura, Yoshinori

    2012-12-01

    The imidazole unit is chemically stable and ubiquitous in biological systems; its proton donor and acceptor moieties easily bind molecules into a dipolar chain. Here we demonstrate that chains of these amphoteric molecules can often be bistable in electric polarity and electrically switchable, even in the crystalline state, through proton tautomerization. Polarization-electric field (P-E) hysteresis experiments reveal a high electric polarization ranging from 5 to 10 μC cm-2 at room temperature. Of these molecules, 2-methylbenzimidazole allows ferroelectric switching in two dimensions due to its pseudo-tetragonal crystal symmetry. The ferroelectricity is also thermally robust up to 400 K, as is that of 5,6-dichloro-2-methylbenzimidazole (up to ~373 K). In contrast, three other benzimidazoles exhibit double P-E hysteresis curves characteristic of antiferroelectricity. The diversity of imidazole substituents is likely to stimulate a systematic exploration of various structure-property relationships and domain engineering in the quest for lead- and rare-metal-free ferroelectric devices.

  14. Phosphonium chloromercurate room temperature ionic liquids of variable composition.

    PubMed

    Metlen, Andreas; Mallick, Bert; Murphy, Richard W; Mudring, Anja-Verena; Rogers, Robin D

    2013-12-16

    The system trihexyl(tetradecyl)phosphonium ([P66614]Cl)/mercury chloride (HgCl2) has been investigated by varying the stoichiometric ratios from 4:1 to 1:2 (25, 50, 75, 100, 150, and 200 mol % HgCl2). All investigated compositions turn out to give rise to ionic liquids (ILs) at room temperature. The prepared ionic liquids offer the possibility to study the structurally and compositionally versatile chloromercurates in a liquid state at low temperatures in the absence of solvents. [P66614]2[HgCl4] is a simple IL with one discrete type of anion, while [P66614]{HgCl3} (with {} indicating a polynuclear arrangement) is an ionic liquid with a variety of polyanionic species, with [Hg2Cl6](2-) apparently being the predominant building block. [P66614]2[Hg3Cl8] and [P66614][Hg2Cl5] appear to be ILs at ambient conditions but lose HgCl2 when heated in a vacuum. For the liquids with the compositions 4:1 and 4:3, more than two discrete ions can be evidenced, namely, [P66614](+), [HgCl4](2-), and Cl(-) and [P66614](+), [HgCl4](2-), and the polynuclear {HgCl3}(-), respectively. The different stoichiometric compositions were characterized by (199)Hg NMR, Raman- and UV-vis spectroscopy, and cyclic voltammetry, among other techniques, and their densities and viscosities were determined. The [P66614]Cl/HgCl2 system shows similarities to the well-known chloroaluminate ILs (e.g., decrease in viscosity with increasing metal content after addition of more than 0.5 mol of HgCl2/mol [P66614]Cl, increasing density with increasing metal content, and the likely formation of polynuclear/polymeric/polyanionic species) but offer the advantage that they are air and water stable. PMID:24274831

  15. Novel room temperature multiferroics on the base of single-phase nanostructured perovskites

    NASA Astrophysics Data System (ADS)

    Glinchuk, Maya D.; Eliseev, Eugene A.; Morozovska, Anna N.

    2014-08-01

    The theoretical description of the nanostructured Pb(Fe1/2Ta1/2)x(Zr0.53Ti0.47)1-xO3 (PFTx-PZT(1-x)) and Pb(Fe1/2Nb1/2)x(Zr0.53Ti0.47)1-xO3 (PFNx-PZT(1-x)) intriguing ferromagnetic, ferroelectric, and magnetoelectric properties at temperatures higher than 100 K are absent to date. The goal of this work is to propose the theoretical description of the physical nature and the mechanisms of the aforementioned properties, including room temperature ferromagnetism, phase diagram dependence on the composition x with a special attention to the multiferroic properties at room temperature, including anomalous large value of magnetoelectric coefficient. The comparison of the developed theory with phase diagrams allow establishing the boundaries between paraelectric, ferroelectric, paramagnetic, antiferromagnetic, ferromagnetic, and magnetoelectric phases, as well as the characteristic features of ferroelectric domain switching by magnetic field are performed and discussed. The experimentally established absence of ferromagnetic phase in PFN, PFT and in the solid solution of PFN with PbTiO3 (PFNx-PT(1-x)) was explained in the framework of the proposed theory.

  16. Room-temperature in situ nuclear spin hyperpolarization from optically pumped nitrogen vacancy centres in diamond

    DOE PAGESBeta

    King, Jonathan P.; Jeong, Keunhong; Vassiliou, Christophoros C.; Shin, Chang S.; Page, Ralph H.; Avalos, Claudia E.; Wang, Hai-Jing; Pines, Alexander

    2015-12-07

    Low detection sensitivity stemming from the weak polarization of nuclear spins is a primary limitation of magnetic resonance spectroscopy and imaging. Methods have been developed to enhance nuclear spin polarization but they typically require high magnetic fields, cryogenic temperatures or sample transfer between magnets. Here we report bulk, room-temperature hyperpolarization of 13C nuclear spins observed via high-field magnetic resonance. The technique harnesses the high optically induced spin polarization of diamond nitrogen vacancy centres at room temperature in combination with dynamic nuclear polarization. We observe bulk nuclear spin polarization of 6%, an enhancement of ~170,000 over thermal equilibrium. The signal ofmore » the hyperpolarized spins was detected in situ with a standard nuclear magnetic resonance probe without the need for sample shuttling or precise crystal orientation. In conclusion, hyperpolarization via optical pumping/dynamic nuclear polarization should function at arbitrary magnetic fields enabling orders of magnitude sensitivity enhancement for nuclear magnetic resonance of solids and liquids under ambient conditions.« less

  17. Room-temperature in situ nuclear spin hyperpolarization from optically pumped nitrogen vacancy centres in diamond

    SciTech Connect

    King, Jonathan P.; Jeong, Keunhong; Vassiliou, Christophoros C.; Shin, Chang S.; Page, Ralph H.; Avalos, Claudia E.; Wang, Hai-Jing; Pines, Alexander

    2015-12-07

    Low detection sensitivity stemming from the weak polarization of nuclear spins is a primary limitation of magnetic resonance spectroscopy and imaging. Methods have been developed to enhance nuclear spin polarization but they typically require high magnetic fields, cryogenic temperatures or sample transfer between magnets. Here we report bulk, room-temperature hyperpolarization of 13C nuclear spins observed via high-field magnetic resonance. The technique harnesses the high optically induced spin polarization of diamond nitrogen vacancy centres at room temperature in combination with dynamic nuclear polarization. We observe bulk nuclear spin polarization of 6%, an enhancement of ~170,000 over thermal equilibrium. The signal of the hyperpolarized spins was detected in situ with a standard nuclear magnetic resonance probe without the need for sample shuttling or precise crystal orientation. In conclusion, hyperpolarization via optical pumping/dynamic nuclear polarization should function at arbitrary magnetic fields enabling orders of magnitude sensitivity enhancement for nuclear magnetic resonance of solids and liquids under ambient conditions.

  18. Study of room temperature magnetoelectric coupling in Ti substituted bismuth ferrite system

    NASA Astrophysics Data System (ADS)

    Kumar, Manoj; Yadav, K. L.

    2006-10-01

    Dielectric, magnetic, and magnetoelectric properties of Ti substituted bismuth ferrite (BiFeO3) ceramic synthesized by solid state reaction are reported. Ti substitution for Fe in BiFeO3 increased the room temperature electrical resistivity by approximately six orders of magnitude and also increased the dielectric constant and reduced the loss tangent. The remanent polarization, coercive field, and maximum polarization were 0.081μC /cm2, 2.571kV/cm, and 0.658μC/cm2, respectively at 20kV/cm. An anomaly in the dielectric constant and loss tangent around Néel temperature was observed. The ferroelectric and magnetic hysteresis loops were measured which are not really saturated in BiFe0.75Ti0.25O3 compound and represented a partial reversal. The magnetoelectric coupling between electric dipoles and magnetic dipoles at room temperature was demonstrated by measuring the effect of magnetic poling on ferroelectric hysteresis loop and the change in the dielectric constant with the external magnetic field.

  19. Room-temperature in situ nuclear spin hyperpolarization from optically pumped nitrogen vacancy centres in diamond

    PubMed Central

    King, Jonathan P.; Jeong, Keunhong; Vassiliou, Christophoros C.; Shin, Chang S.; Page, Ralph H.; Avalos, Claudia E.; Wang, Hai-Jing; Pines, Alexander

    2015-01-01

    Low detection sensitivity stemming from the weak polarization of nuclear spins is a primary limitation of magnetic resonance spectroscopy and imaging. Methods have been developed to enhance nuclear spin polarization but they typically require high magnetic fields, cryogenic temperatures or sample transfer between magnets. Here we report bulk, room-temperature hyperpolarization of 13C nuclear spins observed via high-field magnetic resonance. The technique harnesses the high optically induced spin polarization of diamond nitrogen vacancy centres at room temperature in combination with dynamic nuclear polarization. We observe bulk nuclear spin polarization of 6%, an enhancement of ∼170,000 over thermal equilibrium. The signal of the hyperpolarized spins was detected in situ with a standard nuclear magnetic resonance probe without the need for sample shuttling or precise crystal orientation. Hyperpolarization via optical pumping/dynamic nuclear polarization should function at arbitrary magnetic fields enabling orders of magnitude sensitivity enhancement for nuclear magnetic resonance of solids and liquids under ambient conditions. PMID:26639147

  20. Instantaneous radioiodination of rose bengal at room temperature and a cold kit therefor

    DOEpatents

    O'Brien, Jr., Harold A.; Hupf, Homer B.; Wanek, Philip M.

    1981-01-01

    The disclosure relates to the radioiodination of rose bengal at room temperature and a cold-kit therefor. A purified rose bengal tablet is stirred into acidified ethanol at or near room temperature, until a suspension forms. Reductant-free .sup.125 I.sup.- is added and the resulting mixture stands until the exchange label reaction occurs at room temperature. A solution of sterile isotonic phosphate buffer and sodium hydroxide is added and the final resulting mixture is sterilized by filtration.

  1. Room temperature single-photon detectors for high bit rate quantum key distribution

    SciTech Connect

    Comandar, L. C.; Patel, K. A.; Fröhlich, B. Lucamarini, M.; Sharpe, A. W.; Dynes, J. F.; Yuan, Z. L.; Shields, A. J.; Penty, R. V.

    2014-01-13

    We report room temperature operation of telecom wavelength single-photon detectors for high bit rate quantum key distribution (QKD). Room temperature operation is achieved using InGaAs avalanche photodiodes integrated with electronics based on the self-differencing technique that increases avalanche discrimination sensitivity. Despite using room temperature detectors, we demonstrate QKD with record secure bit rates over a range of fiber lengths (e.g., 1.26 Mbit/s over 50 km). Furthermore, our results indicate that operating the detectors at room temperature increases the secure bit rate for short distances.

  2. Room temperature sterilization of surfaces and fabrics with a one atmosphere uniform glow discharge plasma.

    PubMed

    Kelly-Wintenberg, K; Montie, T C; Brickman, C; Roth, J R; Carr, A K; Sorge, K; Wadsworth, L C; Tsai, P P

    1998-01-01

    We report the results of an interdisciplinary collaboration formed to assess the sterilizing capabilities of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). This newly-invented source of glow discharge plasma (the fourth state of matter) is capable of operating at atmospheric pressure in air and other gases, and of providing antimicrobial active species to surfaces and workpieces at room temperature as judged by viable plate counts. OAUGDP exposures have reduced log numbers of bacteria, Staphylococcus aureus and Escherichia coli, and endospores from Bacillus stearothermophilus and Bacillus subtilis on seeded solid surfaces, fabrics, filter paper, and powdered culture media at room temperature. Initial experimental data showed a two-log10 CFU reduction of bacteria when 2 x 10(2) cells were seeded on filter paper. Results showed > or = 3 log10 CFU reduction when polypropylene samples seeded with E. coli (5 x 10(4)) were exposed, while a 30 s exposure time was required for similar killing with S. aureus-seeded polypropylene samples. The exposure times required to effect > or = 6 log10 CFU reduction of E. coli and S. aureus on polypropylene samples were no longer than 30 s. Experiments with seeded samples in sealed commercial sterilization bags showed little or no differences in exposure times compared to unwrapped samples. Plasma exposure times of less than 5 min generated > or = 5 log10 CFU reduction of commercially prepared Bacillus subtilis spores (1 x 10(5)); 7 min OAUGDP exposures were required to generate a > or = 3 log10 CFU reduction for Bacillus stearothermophilus spores. For all microorganisms tested, a biphasic curve was generated when the number of survivors vs time was plotted in dose-response cures. Several proposed mechanisms of killing at room temperature by the OAUGDP are discussed. PMID:9523458

  3. Room-temperature macromolecular serial crystallography using synchrotron radiation.

    PubMed

    Stellato, Francesco; Oberthür, Dominik; Liang, Mengning; Bean, Richard; Gati, Cornelius; Yefanov, Oleksandr; Barty, Anton; Burkhardt, Anja; Fischer, Pontus; Galli, Lorenzo; Kirian, Richard A; Meyer, Jan; Panneerselvam, Saravanan; Yoon, Chun Hong; Chervinskii, Fedor; Speller, Emily; White, Thomas A; Betzel, Christian; Meents, Alke; Chapman, Henry N

    2014-07-01

    A new approach for collecting data from many hundreds of thousands of microcrystals using X-ray pulses from a free-electron laser has recently been developed. Referred to as serial crystallography, diffraction patterns are recorded at a constant rate as a suspension of protein crystals flows across the path of an X-ray beam. Events that by chance contain single-crystal diffraction patterns are retained, then indexed and merged to form a three-dimensional set of reflection intensities for structure determination. This approach relies upon several innovations: an intense X-ray beam; a fast detector system; a means to rapidly flow a suspension of crystals across the X-ray beam; and the computational infrastructure to process the large volume of data. Originally conceived for radiation-damage-free measurements with ultrafast X-ray pulses, the same methods can be employed with synchrotron radiation. As in powder diffraction, the averaging of thousands of observations per Bragg peak may improve the ratio of signal to noise of low-dose exposures. Here, it is shown that this paradigm can be implemented for room-temperature data collection using synchrotron radiation and exposure times of less than 3 ms. Using lysozyme microcrystals as a model system, over 40 000 single-crystal diffraction patterns were obtained and merged to produce a structural model that could be refined to 2.1 Å resolution. The resulting electron density is in excellent agreement with that obtained using standard X-ray data collection techniques. With further improvements the method is well suited for even shorter exposures at future and upgraded synchrotron radiation facilities that may deliver beams with 1000 times higher brightness than they currently produce. PMID:25075341

  4. Synthesis of tin nanocrystals in room temperature ionic liquids.

    PubMed

    Le Vot, Steven; Dambournet, Damien; Groult, Henri; Ngo, Anh-tu; Petit, Christophe; Rizzi, Cécile; Salzemann, Caroline; Sirieix-Plenet, Juliette; Borkiewicz, Olaf J; Raymundo-Piñero, Encarnación; Gaillon, Laurent

    2014-12-28

    The aim of this work was to investigate the synthesis of tin nanoparticles (NPs) or tin/carbon composites, in room temperature ionic liquids (RTILs), that could be used as structured anode materials for Li-ion batteries. An innovative route for the synthesis of Sn nanoparticles in such media is successfully developed. Compositions, structures, sizes and morphologies of NPs were characterized by high-energy X-ray diffraction (HEXRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). Our findings indicated that (i) metallic tetragonal β-Sn was obtained and (ii) the particle size could be tailored by tuning the nature of the RTILs, leading to nano-sized spherical particles with a diameter ranging from 3 to 10 nm depending on synthesis conditions. In order to investigate carbon composite materials for Li-ion batteries, Sn nanoparticles were successfully deposited on the surface of multi-wall carbon nanotubes (MWCNT). Moreover, electrochemical properties have been studied in relation to a structural study of the nanocomposites. The poor electrochemical performances as a negative electrode in Li-ion batteries is due to a significant amount of RTIL trapped within the pores of the nanotubes as revealed by XPS investigations. This dramatically affected the gravimetric capacity of the composites and limited the diffusion of lithium. The findings of this work however offer valuable insights into the exciting possibilities for synthesis of novel nano-sized particles and/or alloys (e.g. Sn-Cu, Sn-Co, Sn-Ni, etc.) and the importance of carbon morphology in metal pulverization during the alloying/dealloying process as well as prevention of ionic liquid trapping. PMID:25352309

  5. Room temperature molten salt electrolytes for photoelectrochemical applications

    SciTech Connect

    Rajeshwar, K.; DuBow, J.; Singh, P.

    1982-08-01

    Mixtures of aluminum chloride (AlCl/sub 3/) with triethylammonium chloride 1,6-ethyl lutidinium bromide (EtluBr), tert-butyl pyridinium bromide (BPBr), and dialkyl imidazolium chloride (R/sub 2/ImCl), in certain molar ratios yielded ionic liquids at room temperature which were studied with respect to their applicability as electrolytes in photoelectrochemical (PEC) cells. Background voltammograms were obtained for these electrolytes on carbon and n-GaAs electrodes. The anodic stability limit was found to be enhanced on n-GaAs relative to carbon in all cases. The cathodic decomposition potential of the electrolyte showed a smaller positive shift on n-GaAs with the exception of the 3:1 AlCl/sub 3/ BPBr electrolyte. The difference in electrolyte stability behavior on carbon and n-GaAs is interpreted in terms of carrier density effects. Cyclic voltammograms were compared on carbon in the various electrolytes for a model redox system comprising the ferrocene/ferricenium couple. The separation of the cathodic and anodic waves in all the cases was consistent with a quasi-reversible redox behavior--the most sluggish electron transfer being observed in the case of the 3:1 AlCl/sub 3/-BpBr electrolyte. Capacitance-voltage measurements were made on n-GaAs electrodes in contact with the various electrolytes. Flatband-potentials (V /SUB fb/) were deduced from these data using Mott-Schottky plots. The implications of this result for PEC applications and the role of specific ion adsorption of electrolyte species on the electrostatic aspects of the n-GaAs/molten salt electrolyte-interface are discussed with the aid of energy band diagrams.

  6. Threshold analysis of pulsed lasers with application to a room-temperature Co:MgF2 laser

    NASA Technical Reports Server (NTRS)

    Harrison, James; Welford, David; Moulton, Peter F.

    1989-01-01

    Rate-equation calculations are used to model accurately the near-threshold behavior of a Co:MgF2 laser operating at room temperature. The results demonstrate the limitations of the conventional threshold analysis in cases of practical interest. This conclusion is applicable to pulsed solid-state lasers in general. The calculations, together with experimental data, are used to determine emission cross sections for the Co:MgF2 laser.

  7. Room temperature lasing in GeSn alloys: A path to CMOS-compatible infrared lasers

    NASA Astrophysics Data System (ADS)

    Li, Zairui; Zhao, Yun; Gallagher, James; Menéndez, José; Kouvetakis, John; Agha, Imad; Mathews, Jay

    The semiconductor industry has been pushing silicon photonics development for many years, resulting in the realization of many CMOS-compatible optoelectronic devices. However, one challenge that has not been overcome is the development of Si-based lasers. Recently, GeSn alloys grown on Si have shown much promise in the field of infrared optoelectronics. These alloy films are compatible with CMOS processing, have band gaps in the infrared, and the band structure of GeSn can be tuned via Sn concentration to induce direct band gap emission. In this work, we report on room temperature lasing in optically-pumped waveguides fabricated from GeSn films grown epitaxially on Si(100) substrates. The waveguides were defined using standard UV photolithography and dry-etched in a Cl plasma. The end facets were mirror polished, and Al was deposited on one facet to enhance cavity quality. The waveguides were optically-pumped using a 976nm wavelength solid-state laser, and the corresponding emission was measured. The dependence of the emission power on the pump power shows a clear transition between spontaneous and stimulated emission, thereby demonstrating room temperature lasing.

  8. 2010 IEEE Nuclear Science Symposium, Medical Imaging Conference, and Room Temperature Semiconductor Detectors Workshop

    NASA Astrophysics Data System (ADS)

    The Nuclear Science Symposium (NSS) offers an outstanding opportunity for scientists and engineers interested or actively working in the fields of nuclear science, radiation instrumentation, software and their applications, to meet and discuss with colleagues from around the world. The program emphasizes the latest developments in technology and instrumentation and their implementation in experiments for space sciences, accelerators, other radiation environments, and homeland security. The Medical Imaging Conference (MIC) is the foremost international scientific meeting on the physics, engineering and mathematical aspects of nuclear medicine based imaging. As the field develops, multi-modality approaches are becoming more and more important. The content of the MIC reflects this, with a growing emphasis on the methodologies of X-ray, optical and MR imaging as they relate to nuclear imaging techniques. In addition, specialized topics will be addressed in the Short Courses and Workshops programs. The Workshop on Room-Temperature Semiconductor Detectors (RTSD) represents the largest forum of scientists and engineers developing new semiconductor radiation detectors and imaging arrays. Room-temperature solid-state radiation detectors for X-ray, gamma-ray, and neutron radiation are finding increasing applications in such diverse fields as medicine, homeland security, astrophysics and environmental remediation. The objective of this workshop is to provide a forum for discussion of the state of the art of material development for semiconductor, scintillator, and organic materials for detection, materials characterization, device fabrication and technology, electronics and applications.

  9. Effect of short-term room temperature storage on the microbial community in infant fecal samples

    PubMed Central

    Guo, Yong; Li, Sheng-Hui; Kuang, Ya-Shu; He, Jian-Rong; Lu, Jin-Hua; Luo, Bei-Jun; Jiang, Feng-Ju; Liu, Yao-Zhong; Papasian, Christopher J.; Xia, Hui-Min; Deng, Hong-Wen; Qiu, Xiu

    2016-01-01

    Sample storage conditions are important for unbiased analysis of microbial communities in metagenomic studies. Specifically, for infant gut microbiota studies, stool specimens are often exposed to room temperature (RT) conditions prior to analysis. This could lead to variations in structural and quantitative assessment of bacterial communities. To estimate such effects of RT storage, we collected feces from 29 healthy infants (0–3 months) and partitioned each sample into 5 portions to be stored for different lengths of time at RT before freezing at −80 °C. Alpha diversity did not differ between samples with storage time from 0 to 2 hours. The UniFrac distances and microbial composition analysis showed significant differences by testing among individuals, but not by testing between different time points at RT. Changes in the relative abundance of some specific (less common, minor) taxa were still found during storage at room temperature. Our results support previous studies in children and adults, and provided useful information for accurate characterization of infant gut microbiomes. In particular, our study furnished a solid foundation and justification for using fecal samples exposed to RT for less than 2 hours for comparative analyses between various medical conditions. PMID:27226242

  10. Effect of short-term room temperature storage on the microbial community in infant fecal samples.

    PubMed

    Guo, Yong; Li, Sheng-Hui; Kuang, Ya-Shu; He, Jian-Rong; Lu, Jin-Hua; Luo, Bei-Jun; Jiang, Feng-Ju; Liu, Yao-Zhong; Papasian, Christopher J; Xia, Hui-Min; Deng, Hong-Wen; Qiu, Xiu

    2016-01-01

    Sample storage conditions are important for unbiased analysis of microbial communities in metagenomic studies. Specifically, for infant gut microbiota studies, stool specimens are often exposed to room temperature (RT) conditions prior to analysis. This could lead to variations in structural and quantitative assessment of bacterial communities. To estimate such effects of RT storage, we collected feces from 29 healthy infants (0-3 months) and partitioned each sample into 5 portions to be stored for different lengths of time at RT before freezing at -80 °C. Alpha diversity did not differ between samples with storage time from 0 to 2 hours. The UniFrac distances and microbial composition analysis showed significant differences by testing among individuals, but not by testing between different time points at RT. Changes in the relative abundance of some specific (less common, minor) taxa were still found during storage at room temperature. Our results support previous studies in children and adults, and provided useful information for accurate characterization of infant gut microbiomes. In particular, our study furnished a solid foundation and justification for using fecal samples exposed to RT for less than 2 hours for comparative analyses between various medical conditions. PMID:27226242

  11. Pt@MOF-177: synthesis, room-temperature hydrogen storage and oxidation catalysis.

    PubMed

    Proch, Sebastian; Herrmannsdörfer, Justus; Kempe, Rhett; Kern, Christoph; Jess, Andreas; Seyfarth, Lena; Senker, Jürgen

    2008-01-01

    The gas-phase loading of [Zn(4)O(btb)(2)](8) (MOF-177; H(3)btb=1,3,5-benzenetribenzoic acid) with the volatile platinum precursor [Me(3)PtCp'] (Cp'=methylcyclopentadienyl) was confirmed by solid state (13)C magic angle spinning (MAS)-NMR spectroscopy. Subsequent reduction of the inclusion compound [Me(3)PtCp'](4)@MOF-177 by hydrogen at 100 bar and 100 degrees C for 24 h was carried out and gave rise to the formation of platinum nanoparticles in a size regime of 2-5 nm embedded in the unchanged MOF-177 host lattice as confirmed by transmission electron microscopy (TEM) micrographs and powder X-ray diffraction (PXRD). The room-temperature hydrogen adsorption of Pt@MOF-177 has been followed in a gravimetric fashion (magnetic suspension balance) and shows almost 2.5 wt % in the first cycle, but is decreased down to 0.5 wt % in consecutive cycles. The catalytic activity of Pt@MOF-177 towards the solvent- and base-free room temperature oxidation of alcohols in air has been tested and shows Pt@MOF-177 to be an efficient catalyst in the oxidation of alcohols. PMID:18666269

  12. Room-temperature near-infrared high-Q perovskite whispering-gallery planar nanolasers.

    PubMed

    Zhang, Qing; Ha, Son Tung; Liu, Xinfeng; Sum, Tze Chien; Xiong, Qihua

    2014-10-01

    Near-infrared (NIR) solid-state micro/nanolasers are important building blocks for true integration of optoelectronic circuitry. Although significant progress has been made in III-V nanowire lasers with achieving NIR lasing at room temperature, challenges remain including low quantum efficiencies and high Auger losses. Importantly, the obstacles toward integrating one-dimensional nanowires on the planar ubiquitous Si platform need to be effectively tackled. Here we demonstrate a new family of planar room-temperature NIR nanolasers based on organic-inorganic perovskite CH3NH3PbI(3-a)X(a) (X = I, Br, Cl) nanoplatelets. Their large exciton binding energies, long diffusion lengths, and naturally formed high-quality planar whispering-gallery mode cavities ensure adequate gain and efficient optical feedback for low-threshold optically pumped in-plane lasing. We show that these remarkable wavelength tunable whispering-gallery nanolasers can be easily integrated onto conductive platforms (Si, Au, indium tin oxide, and so forth). Our findings open up a new class of wavelength tunable planar nanomaterials potentially suitable for on-chip integration. PMID:25118830

  13. Highly Efficient Room Temperature Spin Injection Using Spin Filtering in MgO

    NASA Astrophysics Data System (ADS)

    Jiang, Xin

    2007-03-01

    Efficient electrical spin injection into GaAs/AlGaAs quantum well structures was demonstrated using CoFe/MgO tunnel spin injectors at room temperature. The spin polarization of the injected electron current was inferred from the circular polarization of electroluminescence from the quantum well. Polarization values as high as 57% at 100 K and 47% at 290 K were obtained in a perpendicular magnetic field of 5 Tesla. The interface between the tunnel spin injector and the GaAs interface remained stable even after thermal annealing at 400 ^oC. The temperature dependence of the electron-hole recombination time and the electron spin relaxation time in the quantum well was measured using time-resolved optical techniques. By taking into account of these properties of the quantum well, the intrinsic spin injection efficiency can be deduced. We conclude that the efficiency of spin injection from a CoFe/MgO spin injector is nearly independent of temperature and, moreover, is highly efficient with an efficiency of ˜ 70% for the temperature range studied (10 K to room temperature). Tunnel spin injectors are thus highly promising components of future semiconductor spintronic devices. Collaborators: Roger Wang^1, 3, Gian Salis^2, Robert Shelby^1, Roger Macfarlane^1, Seth Bank^3, Glenn Solomon^3, James Harris^3, Stuart S. P. Parkin^1 ^1 IBM Almaden Research Center, San Jose, CA 95120 ^2 IBM Zurich Research Laboratory, S"aumerstrasse 4, 8803 R"uschlikon, Switzerland ^3 Solid States and Photonics Laboratory, Stanford University, Stanford, CA 94305

  14. Picosecond Lifetimes with High Quantum Yields from Single-Photon-Emitting Colloidal Nanostructures at Room Temperature.

    PubMed

    Bidault, Sébastien; Devilez, Alexis; Maillard, Vincent; Lermusiaux, Laurent; Guigner, Jean-Michel; Bonod, Nicolas; Wenger, Jérôme

    2016-04-26

    Minimizing the luminescence lifetime while maintaining a high emission quantum yield is paramount in optimizing the excitation cross-section, radiative decay rate, and brightness of quantum solid-state light sources, particularly at room temperature, where nonradiative processes can dominate. We demonstrate here that DNA-templated 60 and 80 nm diameter gold nanoparticle dimers, featuring one fluorescent molecule, provide single-photon emission with lifetimes that can fall below 10 ps and typical quantum yields in a 45-70% range. Since these colloidal nanostructures are obtained as a purified aqueous suspension, fluorescence spectroscopy can be performed on both fixed and freely diffusing nanostructures to quantitatively estimate the distributions of decay rate and fluorescence intensity enhancements. These data are in excellent agreement with theoretical calculations and demonstrate that millions of bright fluorescent nanostructures, with radiative lifetimes below 100 ps, can be produced in parallel. PMID:26972678

  15. Coherent control of single spins in silicon carbide at room temperature.

    PubMed

    Widmann, Matthias; Lee, Sang-Yun; Rendler, Torsten; Son, Nguyen Tien; Fedder, Helmut; Paik, Seoyoung; Yang, Li-Ping; Zhao, Nan; Yang, Sen; Booker, Ian; Denisenko, Andrej; Jamali, Mohammad; Momenzadeh, S Ali; Gerhardt, Ilja; Ohshima, Takeshi; Gali, Adam; Janzén, Erik; Wrachtrup, Jörg

    2015-02-01

    Spins in solids are cornerstone elements of quantum spintronics. Leading contenders such as defects in diamond or individual phosphorus dopants in silicon have shown spectacular progress, but either lack established nanotechnology or an efficient spin/photon interface. Silicon carbide (SiC) combines the strength of both systems: it has a large bandgap with deep defects and benefits from mature fabrication techniques. Here, we report the characterization of photoluminescence and optical spin polarization from single silicon vacancies in SiC, and demonstrate that single spins can be addressed at room temperature. We show coherent control of a single defect spin and find long spin coherence times under ambient conditions. Our study provides evidence that SiC is a promising system for atomic-scale spintronics and quantum technology. PMID:25437256

  16. Room-temperature synthesis of BiOI with tailorable (001) facets and enhanced photocatalytic activity.

    PubMed

    He, Rongan; Zhang, Jinfeng; Yu, Jiaguo; Cao, Shaowen

    2016-09-15

    The photocatalytic activity of bismuth oxyhalides largely depends on their morphologies and microstructures. In this work, hierarchically structured bismuth oxyiodide (BiOI) with tunable ratios of (110) and (001) facets are fabricated through a facile route combining solid-state reaction with subsequent hydrolysis at room temperature. The hierarchical structures endow BiOI with excellent visible-light photocatalytic performance for phenol degradation. Besides, the optimal ratio of (001) and (110) surfaces also plays an important role in enhancing the photocatalytic activity of BiOI. DFT calculation demonstrates that a surface heterojunction formed between (001) and (110) surfaces can improve the separation of electrons and holes on different surfaces and thus enhance the photocatalytic activity. PMID:27295322

  17. Room-temperature quantum microwave emitters based on spin defects in silicon carbide

    NASA Astrophysics Data System (ADS)

    Kraus, H.; Soltamov, V. A.; Riedel, D.; Väth, S.; Fuchs, F.; Sperlich, A.; Baranov, P. G.; Dyakonov, V.; Astakhov, G. V.

    2014-02-01

    Atomic-scale defects in silicon carbide are always present and usually limit the performance of this material in high-power electronics and radiofrequency communication. Here, we reveal a family of homotypic silicon vacancy defects in silicon carbide exhibiting attractive spin properties. In particular, the defect spins can be initialized and read out even at room temperature by means of optically detected magnetic resonance, suggesting appealing applications such as spin qubits and spin magnetometers. Using this technique we detect two-quantum spin resonances, providing strong evidence for the S=3/2 ground state of the silicon vacancy defects. The optically induced population inversion of these high-spin ground states leads to stimulated microwave emission, which we directly observed in our silicon carbide crystals. The analysis based on the experimentally obtained parameters shows that this property can be used to implement solid-state masers and extraordinarily sensitive radiofrequency amplifiers.

  18. Ordered iron aluminide alloys having an improved room-temperature ductility and method thereof

    SciTech Connect

    Sikka, V.K.

    1992-01-28

    This patent describes a method for improving the room temperature ductility and high temperature strength of iron aluminide intermetallic alloys. It comprises: thermomechanically working of the alloys ; heating the alloys; and rapidly cooling the alloys.

  19. N2-broadening coefficients of methyl chloride at room temperature

    NASA Astrophysics Data System (ADS)

    Bray, C.; Jacquemart, D.; Buldyreva, J.; Lacome, N.; Perrin, A.

    2012-07-01

    Methyl chloride is of interest for atmospheric applications, since this molecule is directly involved in the catalytic destruction of ozone in the lower stratosphere. In a previous work [Bray et al. JQSRT 2011;112:2446], lines positions and intensities of self-perturbed 12CH335Cl and 12CH337Cl have been studied into details for the 3.4 μm spectral region. The present work is focused on measurement and calculation of N2-broadening coefficients of the 12CH335Cl and 12CH337Cl isotopologues. High-resolution Fourier Transform spectra of CH3Cl-N2 mixtures at room-temperature have been recorded between 2800 and 3200 cm-1 at LADIR (using a classical source) and between 47 and 59 cm-1 at SOLEIL (using the synchrotron source on the AILES beamline). 612 mid-infrared transitions of the ν1 band and 86 far-infrared transitions of the pure rotational band have been analyzed using a multispectrum fitting procedure. Average accuracy on the deduced N2-broadening coefficients has been estimated to 5% and 10% in the mid- and far-infrared spectral regions, respectively. The J- and K-rotational dependences of these coefficients have been observed in the mid-infrared region and then a simulation has been performed using an empirical model for 0≤J≤50, K≤9. The 12CH335Cl-N2 line widths for 0≤J≤50 and K≤10 of the ν1 band and for 55≤J≤67 and K≤15 of the pure rotational band have been computed using a semi-classical approach involving exact trajectories and a real symmetric-top geometry of the active molecule. Finally, a global comparison with the experimental and theoretical data existing in the literature has been performed. Similar J- and K-rotational dependences have been appeared while no clear evidence for any vibrational or isotopic dependences have been pointed out.

  20. Tomographic reconstruction of indoor spatial temperature distributions using room impulse responses

    NASA Astrophysics Data System (ADS)

    Bleisteiner, M.; Barth, M.; Raabe, A.

    2016-03-01

    Temperature can be estimated by acoustic travel time measurements along known sound paths. By using a multitude of known sound paths in combination with a tomographic reconstruction technique a spatial and temporal resolution of the temperature field can be achieved. Based on it, this article focuses on an experimental method in order to determine the spatially differentiated development of room temperature with only one loudspeaker and one microphone. The theory of geometrical room acoustics is being used to identify sound paths under consideration of reflections. The travel time along a specific sound path is derived from the room impulse response. Temporal variances in room impulse response can be attributed primarily to a change in air temperature and airflow. It is shown that in the absence of airflow a 3D acoustic monitoring of the room temperature can be realized with a fairly limited use of hardware.

  1. Applications of room temperature ionic liquids in interfacial polymerization

    NASA Astrophysics Data System (ADS)

    Zhu, Lining

    2006-12-01

    Room temperature ionic liquids (ILs), with their unique physical and chemical properties, have been of great interest in various areas of chemical science and engineering during the last decade. In this dissertation, polyurea and polyamide films with surface nanostructures were synthesized by interfacial polymerization (IP) with ILs without stirring. Both polymers were prepared at the interface between n-hexane and a series of 1-alkyl-3-methylimidazolium ILs. Nanoporous or nanofibrous polymer morphologies with various sizes ranging from 50 to 500 nm and geometries, depending on the ILs used, were observed by scanning electron microscopy (SEM). A correlation length of ˜20nm and a suppression of three-dimensional (3-D) crystalline structure of the polyurea were found by small angle X-ray scattering (SAXS) and X-ray diffraction (XRD), respectively. FTIR spectra showed no significant changes in the chemical composition of the polymer by the employment of ILs. The peculiar nanostructure of the polymer could be ascribed to the intermolecular interactions between the ILs and the polymer, which affected the development of the polymer morphology. The polyamides prepared with ILs showed larger intrinsic viscosities, and consequently higher molecular weights, compared to the one prepared without ILs; this could be due to the prevention of the side reaction between sebacoyl chloride and water. The enhancement of the molecular weight renders a better thermal stability to the polyamide film, as revealed by thermogravimetric analysis (TGA) which showed a higher decomposition temperature. Coating of fine particulates with polyurea by IP has been developed. With increasing stirring speed in the coating process, a decreased mean particle size and a narrower particle size distribution, as well as a lower coating weight percentage were found by particle size analysis and TGA, respectively. A Porous coating layer was formed in the IP coating in the presence of ILs. The reaction

  2. Ordered iron aluminide alloys having an improved room-temperature ductility and method thereof

    DOEpatents

    Sikka, Vinod K.

    1992-01-01

    A process is disclosed for improving the room temperature ductility and strength of iron aluminide intermetallic alloys. The process involves thermomechanically working an iron aluminide alloy by means which produce an elongated grain structure. The worked alloy is then heated at a temperature in the range of about 650.degree. C. to about 800.degree. C. to produce a B2-type crystal structure. The alloy is rapidly cooled in a moisture free atmosphere to retain the B2-type crystal structure at room temperature, thus providing an alloy having improved room temperature ductility and strength.

  3. Intermediate Temperature Solid Oxide Fuel Cell Development

    SciTech Connect

    S. Elangovan; Scott Barnett; Sossina Haile

    2008-06-30

    Solid oxide fuel cells (SOFCs) are high efficiency energy conversion devices. Present materials set, using yttria stabilized zirconia (YSZ) electrolyte, limit the cell operating temperatures to 800 C or higher. It has become increasingly evident however that lowering the operating temperature would provide a more expeditious route to commercialization. The advantages of intermediate temperature (600 to 800 C) operation are related to both economic and materials issues. Lower operating temperature allows the use of low cost materials for the balance of plant and limits degradation arising from materials interactions. When the SOFC operating temperature is in the range of 600 to 700 C, it is also possible to partially reform hydrocarbon fuels within the stack providing additional system cost savings by reducing the air preheat heat-exchanger and blower size. The promise of Sr and Mg doped lanthanum gallate (LSGM) electrolyte materials, based on their high ionic conductivity and oxygen transference number at the intermediate temperature is well recognized. The focus of the present project was two-fold: (a) Identify a cell fabrication technique to achieve the benefits of lanthanum gallate material, and (b) Investigate alternative cathode materials that demonstrate low cathode polarization losses at the intermediate temperature. A porous matrix supported, thin film cell configuration was fabricated. The electrode material precursor was infiltrated into the porous matrix and the counter electrode was screen printed. Both anode and cathode infiltration produced high performance cells. Comparison of the two approaches showed that an infiltrated cathode cells may have advantages in high fuel utilization operations. Two new cathode materials were evaluated. Northwestern University investigated LSGM-ceria composite cathode while Caltech evaluated Ba-Sr-Co-Fe (BSCF) based pervoskite cathode. Both cathode materials showed lower polarization losses at temperatures as low as 600

  4. A STUDY ON ASH PARTICLE DISTRIBUTION CHARACTERISITICS OF CANDLE FILTER SURFACE REGENERATION AT ROOM TEMPERATURE

    SciTech Connect

    Vasudevan, V.; Kang, B.S-J.; Johnson, E.K.

    2002-09-19

    Ceramic barrier filtration is a leading technology employed in hot gas filtration. Hot gases loaded with ash particle flow through the ceramic candle filters and deposit ash on their outer surface. The deposited ash is periodically removed using back pulse cleaning jet, known as surface regeneration. The cleaning done by this technique still leaves some residual ash on the filter surface, which over a period of time sinters, forms a solid cake and leads to mechanical failure of the candle filter. A room temperature testing facility (RTTF) was built to gain more insight into the surface regeneration process before testing commenced at high temperature. RTTF was instrumented to obtain pressure histories during the surface regeneration process and a high-resolution high-speed imaging system was integrated in order to obtain pictures of the surface regeneration process. The objective of this research has been to utilize the RTTF to study the surface regeneration process at the convenience of room temperature conditions. The face velocity of the fluidized gas, the regeneration pressure of the back pulse and the time to build up ash on the surface of the candle filter were identified as the important parameters to be studied. Two types of ceramic candle filters were used in the study. Each candle filter was subjected to several cycles of ash build-up followed by a thorough study of the surface regeneration process at different parametric conditions. The pressure histories in the chamber and filter system during build-up and regeneration were then analyzed. The size distribution and movement of the ash particles during the surface regeneration process was studied. Effect of each of the parameters on the performance of the regeneration process is presented. A comparative study between the two candle filters with different characteristics is presented.

  5. Long-term room temperature preservation of corpse soft tissue: an approach for tissue sample storage

    PubMed Central

    2011-01-01

    Background Disaster victim identification (DVI) represents one of the most difficult challenges in forensic sciences, and subsequent DNA typing is essential. Collected samples for DNA-based human identification are usually stored at low temperature to halt the degradation processes of human remains. We have developed a simple and reliable procedure for soft tissue storage and preservation for DNA extraction. It ensures high quality DNA suitable for PCR-based DNA typing after at least 1 year of room temperature storage. Methods Fragments of human psoas muscle were exposed to three different environmental conditions for diverse time periods at room temperature. Storage conditions included: (a) a preserving medium consisting of solid sodium chloride (salt), (b) no additional substances and (c) garden soil. DNA was extracted with proteinase K/SDS followed by organic solvent treatment and concentration by centrifugal filter devices. Quantification was carried out by real-time PCR using commercial kits. Short tandem repeat (STR) typing profiles were analysed with 'expert software'. Results DNA quantities recovered from samples stored in salt were similar up to the complete storage time and underscored the effectiveness of the preservation method. It was possible to reliably and accurately type different genetic systems including autosomal STRs and mitochondrial and Y-chromosome haplogroups. Autosomal STR typing quality was evaluated by expert software, denoting high quality profiles from DNA samples obtained from corpse tissue stored in salt for up to 365 days. Conclusions The procedure proposed herein is a cost efficient alternative for storage of human remains in challenging environmental areas, such as mass disaster locations, mass graves and exhumations. This technique should be considered as an additional method for sample storage when preservation of DNA integrity is required for PCR-based DNA typing. PMID:21846338

  6. Nano-structured TiO2 film fabricated at room temperature and its acoustic properties

    PubMed Central

    Zhu, Jie; Cao, Wenwu; Jiang, Bei; Zhang, D S; Zheng, H; Zhou, Q; Shung, K K

    2009-01-01

    Nano-structured TiO2 thin film has been successfully fabricated at room temperature. Using a quarter wavelength characterization method, we have measured the acoustic impedance of this porous film, which can be adjusted from 5.3 to 7.19 Mrayl by curing it at different temperatures. The uniform microstructure and easy fabrication at room temperature make this material an excellent candidate for matching layers of ultra-high frequency ultrasonic imaging transducers. PMID:19672322

  7. Substrate Temperature Effects on Room Temperature Sensing Properties of Nanostructured ZnO Thin Films.

    PubMed

    Reddy, Jonnala Rakesh; Mani, Ganesh Kumar; Shankar, Prabakaran; Rayappan, John Bosco Balaguru

    2016-01-01

    Zinc oxide (ZnO) thin films were deposited on glass substrates using chemical spray pyrolysis technique at different substrate temperatures such as 523, 623 and 723 K. X-ray diffraction (XRD) patterns confirmed the formation of polycrystalline films with hexagonal wurtzite crystal structure and revealed the change in preferential orientation of the crystal planes. Scanning electron micrographs showed the formation of uniformly distributed spherical shaped grains at low deposition temperature and pebbles like structure at the higher temperature. Transmittance of 85% was observed for the film deposited at 723 K. The band gap of the films was found to be increased from 3.15 to 3.23 eV with a rise in deposition temperature. The electrical conductivity of the films was found to be improved with an increase in substrate temperature. Surface of ZnO thin films deposited at 523 K, 623 K and 723 K were found to be hydrophobic with the contact angles of 92°, 105° and 128° respectively. The room temperature gas sensing characteristics of all the films were studied and found that the film deposited at 623 K showed a better response towards ammonia vapour. PMID:27398478

  8. High temperature seals for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Parihar, Shailendra S.

    Solid Oxide Fuel cells (SOFCs) represent a clean and efficient alternative to existing methods of energy production. But, they need hermetic seals to prevent fuel-oxidant mixing within the stack. Glasses are attractive options for fabrication of these high temperature seals but suffer from their inherent brittleness and tend to crack during thermal cycling. In this study, an innovative concept of self-healing glass seals is developed to solve the problem of cracking of glasses in a SOFC seal. Rationale behind this concept is that a glass of suitable viscosity characteristics can flow and heal cracks at SOFC operating temperatures and thus can provide seals which can self-repair. A novel method, based on in-situ video imaging of cracks on the glass surface during high temperature treatment is developed and used to select and evaluate the suitability of different glasses for making self-healing seals. Promising glasses are studied experimentally to determine kinetics of healing of Vickers indented cracks at various temperatures. In addition, the effect of crystallization of glass on its healing kinetics is studied. A model is developed for crack healing behavior and is used to validate the experimental data. Studies on Cracks healing and crystallization of glasses showed that glasses with no crystallization tendency show fast crack healing response, whereas glasses which crystallize display sluggish healing. A glass displaying fast healing kinetics and good stability against crystallization is used to fabricate self healing glass seals for SOFCs. Seals fabricated using this glass not only remained hermetic but also maintained their self i healing ability for as long as 3000 hours at 800°C and 300 thermal cycles between room temperature and 800°C. These results clearly indicated that self-healing glasses are promising candidates for SOFC seals. Key words. Solid Oxide Fuel Cells, Glass Seals, Self-Healing Glasses, Seal Leak Testing.

  9. FAST TRACK COMMUNICATION: Magnetic control of large room-temperature polarization

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok; Sharma, G. L.; Katiyar, R. S.; Pirc, R.; Blinc, R.; Scott, J. F.

    2009-09-01

    Numerous authors have referred to room-temperature magnetic switching of large electric polarizations as 'the Holy Grail' of magnetoelectricity. We report this long-sought effect, obtained using a new physical process of coupling between magnetic and ferroelectric nanoregions. Solid state solutions of PFW [Pb(Fe2/3W1/3)O3] and PZT [Pb(Zr0.53Ti0.47)O3] exhibit some bi-relaxor qualities, with both ferroelectric relaxor characteristics and magnetic relaxor phenomena. Near 20% PFW the ferroelectric relaxor state is nearly unstable at room temperature against long-range ferroelectricity. Here we report magnetic switching between the normal ferroelectric state and a magnetically quenched ferroelectric state that resembles relaxors. This gives both a new room-temperature, single-phase, multiferroic magnetoelectric, (PbFe0.67W0.33O3)0.2(PbZr0.53Ti0.47O3)0.8 ('0.2PFW/0.8PZT'), with polarization, loss (<1%), and resistivity (typically 108-109 Ω cm) equal to or superior to those of BiFeO3, and also a new and very large magnetoelectric effect: switching not from +Pr to -Pr with applied H, but from Pr to zero with applied H of less than a tesla. This switching of the polarization occurs not because of a conventional magnetically induced phase transition, but because of dynamic effects: increasing H lengthens the relaxation time by 500 × from<200 ns to>100 µs, and it strongly couples the polarization relaxation and spin relaxations. The diverging polarization relaxation time accurately fits a modified Vogel-Fulcher equation in which the freezing temperature Tf is replaced by a critical freezing field Hf that is 0.92 ± 0.07 T. This field dependence and the critical field Hc are derived analytically from the spherical random bond random field model with no adjustable parameters and an E2H2 coupling. This device permits three-state logic (+Pr,0,-Pr) and a condenser with >5000% magnetic field change in its capacitance; for H = 0 the coercive voltage is 1.4 V across 300 nm for

  10. Broadly tunable monolithic room-temperature terahertz quantum cascade laser sources.

    PubMed

    Jung, Seungyong; Jiang, Aiting; Jiang, Yifan; Vijayraghavan, Karun; Wang, Xiaojun; Troccoli, Mariano; Belkin, Mikhail A

    2014-01-01

    Electrically pumped room-temperature semiconductor sources of tunable terahertz radiation in 1-5 THz spectral range are highly desired to enable compact instrumentation for THz sensing and spectroscopy. Quantum cascade lasers with intra-cavity difference-frequency generation are currently the only room-temperature electrically pumped semiconductor sources that can operate in the entire 1-5 THz spectral range. Here we demonstrate that this technology is suitable to implementing monolithic room-temperature terahertz tuners with broadband electrical control of the emission frequency. Experimentally, we demonstrate ridge waveguide devices electrically tunable between 3.44 and 4.02 THz. PMID:25014053

  11. Local magnetoresistance in Fe/MgO/Si lateral spin valve at room temperature

    SciTech Connect

    Sasaki, Tomoyuki Koike, Hayato; Oikawa, Tohru; Suzuki, Toshio; Ando, Yuichiro; Suzuki, Yoshishige; Shiraishi, Masashi

    2014-02-03

    Room temperature local magnetoresistance in two-terminal scheme is reported. By employing 1.6 nm-thick MgO tunnel barrier, spin injection efficiency is increased, resulting in large non-local magnetoresistance. The magnitude of the non-local magnetoresistance is estimated to be 0.0057 Ω at room temperature. As a result, a clear rectangle signal is observed in local magnetoresistance measurement even at room temperature. We also investigate the origin of local magnetoresistance by measuring the spin accumulation voltage of each contact separately.

  12. Demonstration of a room temperature 2.48-2.75 THz coherent spectroscopy source.

    PubMed

    Pearson, John C; Drouin, Brian J; Maestrini, Alain; Mehdi, Imran; Ward, John; Lin, Robert H; Yu, Shanshan; Gill, John J; Thomas, Bertrand; Lee, Choonsup; Chattopadhyay, Goutam; Schlecht, Erich; Maiwald, Frank W; Goldsmith, Paul F; Siegel, Peter

    2011-09-01

    We report the first demonstration of a continuous wave coherent source covering 2.48-2.75 THz, with greater than 10% instantaneous tuning bandwidth and having 1-14 μW of output power at room temperature. This source is based on a 91.8-101.8 GHz synthesizer followed by a power amplifier and three cascaded frequency triplers. It demonstrates for the first time that purely electronic solid-state sources can generate a useful amount of power in a region of the electromagnetic spectrum where lasers (solid state or gas) were previously the only available coherent sources. The bandwidth, agility, and operability of this THz source have enabled wideband, high resolution spectroscopic measurements of water, methanol, and carbon monoxide with a resolution and signal-to-noise ratio unmatched by any other existing system, providing new insight in the physics of these molecules. Furthermore, the power and optical beam quality are high enough to observe the Lamb-dip effect in water. The source frequency has an absolute accuracy better than 1 part in 10(12) and the spectrometer achieves sub-Doppler frequency resolution better than 1 part in 10(8). The harmonic purity is better than 25 dB. This source can serve as a coherent signal for absorption spectroscopy, a local oscillator for a variety of heterodyne systems and can be used as a method for precision control of more powerful but much less frequency agile quantum mechanical terahertz sources. PMID:21974571

  13. Demonstration of a room temperature 2.48-2.75 THz coherent spectroscopy source

    NASA Astrophysics Data System (ADS)

    Pearson, John C.; Drouin, Brian J.; Maestrini, Alain; Mehdi, Imran; Ward, John; Lin, Robert H.; Yu, Shanshan; Gill, John J.; Thomas, Bertrand; Lee, Choonsup; Chattopadhyay, Goutam; Schlecht, Erich; Maiwald, Frank W.; Goldsmith, Paul F.; Siegel, Peter

    2011-09-01

    We report the first demonstration of a continuous wave coherent source covering 2.48-2.75 THz, with greater than 10% instantaneous tuning bandwidth and having 1-14 μW of output power at room temperature. This source is based on a 91.8-101.8 GHz synthesizer followed by a power amplifier and three cascaded frequency triplers. It demonstrates for the first time that purely electronic solid-state sources can generate a useful amount of power in a region of the electromagnetic spectrum where lasers (solid state or gas) were previously the only available coherent sources. The bandwidth, agility, and operability of this THz source have enabled wideband, high resolution spectroscopic measurements of water, methanol, and carbon monoxide with a resolution and signal-to-noise ratio unmatched by any other existing system, providing new insight in the physics of these molecules. Furthermore, the power and optical beam quality are high enough to observe the Lamb-dip effect in water. The source frequency has an absolute accuracy better than 1 part in 1012 and the spectrometer achieves sub-Doppler frequency resolution better than 1 part in 108. The harmonic purity is better than 25 dB. This source can serve as a coherent signal for absorption spectroscopy, a local oscillator for a variety of heterodyne systems and can be used as a method for precision control of more powerful but much less frequency agile quantum mechanical terahertz sources.

  14. Fabrication of Wollastonite Coatings on Zirconia by Room Temperature Spray Process.

    PubMed

    Lee, Jong Kook; Eum, Sangcheol; Kim, Jaehong; Hwang, Kyu Hong

    2016-02-01

    Wollastonite-based bioceramic powders were synthesized by solid-state reaction between calcite and silica powder. To control the phase and bioactivity of wollastonite, we also prepared four kinds of wollastonite-based bioceramics by adding an enstatite (MgSiO3) powder. After solid state reaction at 1000-1300 degrees C, micron-sized powders were obtained by milling and screening. By using these powders, wollastonite coatings were fabricated on zirconia substrates by a room temperature spray process, and their microstructure and composition under different coating condition were investigated. Wollastonite coatings on zirconia substrates were formed with the homogeneous microstructure and nanoscaled grain size. The phase composition of the resultant wollastonite coatings was similar to that of the starting powders, however, the grain size of the wollastonite particles was reduced to about 100 nm due to their formation by particle impaction and fracture. The wollastonite coating layer exhibited bioactivity in a stimulated body fluid and forming ability of 25 nm sized-hydroxyapatite precipitates of during in vitro test in SBF solution. PMID:27433716

  15. Room temperature giant baroresistance and magnetoresistance and its tunability in Pd doped FeRh

    NASA Astrophysics Data System (ADS)

    Kushwaha, Pallavi; Bag, Pallab; Rawat, R.

    2015-01-01

    We report room temperature giant baroresistance (≈128%) in Fe49(Rh0.93Pd0.07)51. With the application of external pressure (P) and magnetic field (H), the temperature range of giant baroresistance (≈600% at 5 K, 19.9 kilobars and 8 T) and magnetoresistance (≈ -85% at 5 K and 8 T) can be tuned from 5 K to well above room temperature. It is shown that under external pressure, antiferromagnetic state is stabilized at room temperature and shows giant magnetoresistance (≈-55%). Due to coupled magnetic and lattice changes, the isothermal change in resistivity at room temperature under pressure (at constant H) as well as magnetic field (at constant P) can be scaled together to a single curve, when plotted as a function of X = T + 12.8 × H - 7.3 × P.

  16. Light-emitting diodes for solid-state lighting: searching room for improvements

    NASA Astrophysics Data System (ADS)

    Karpov, Sergey Y.

    2016-03-01

    State-of-the art light-emitting diodes (LEDs) for solid-state lighting (SSL) are reviewed with the focus on their efficiency and ways for its improvement. Mechanisms of the LED efficiency losses are considered on the heterostructure, chip, and device levels, including high-current efficiency droop, recombination losses, "green gap", current crowding, Stokes losses, etc. Materials factors capable of lowering the LED efficiency, like composition fluctuations in InGaN alloys and plastic stress relaxation in device heterostructures, are also considered. Possible room for the efficiency improvement is discussed along with advanced schemes of color mixing and LED parameters optimal for generation of high-quality white light.

  17. Stability limit of room air temperature of a VAV system

    SciTech Connect

    Matsuba, Tadahiko; Kamimura, Kazuyuki; Kasahara, Masato; Kimbara, Akiomi; Kurosu, Shigeru; Murasawa, Itaru; Hashimoto, Yukihiko

    1998-12-31

    To control heating, ventilating, and air-conditioning (HVAC) systems, it has been necessary to accept an analog system controlled mainly by proportional-plus-integral-plus-derivative (PID) action. However, when conventional PID controllers are replaced with new digital controllers by selecting the same PID parameters as before, the control loops have often got into hunting phenomena, which result in undamped oscillations. Unstable control characteristics (such as huntings) are thought to be one of the crucial problems faced by field operators. The PID parameters must be carefully selected to avoid instabilities. In this study, a room space is simulated as a thermal system that is air-conditioned by a variable-air-volume (VAV) control system. A dynamic room model without infiltration or exfiltration, which is directly connected to a simple air-handling unit without an economizer, is developed. To explore the possible existence of huntings, a numerical system model is formulated as a bilinear system with time-delayed feedback, and a parametric analysis of the stability limit is presented. Results are given showing the stability region affected by the selection of control and system parameters. This analysis was conducted to help us tune the PID controllers for optimal HVAC control.

  18. Designing switchable polarization and magnetization at room temperature in an oxide

    NASA Astrophysics Data System (ADS)

    Mandal, P.; Pitcher, M. J.; Alaria, J.; Niu, H.; Borisov, P.; Stamenov, P.; Claridge, J. B.; Rosseinsky, M. J.

    2015-09-01

    Ferroelectric and ferromagnetic materials exhibit long-range order of atomic-scale electric or magnetic dipoles that can be switched by applying an appropriate electric or magnetic field, respectively. Both switching phenomena form the basis of non-volatile random access memory, but in the ferroelectric case, this involves destructive electrical reading and in the magnetic case, a high writing energy is required. In principle, low-power and high-density information storage that combines fast electrical writing and magnetic reading can be realized with magnetoelectric multiferroic materials. These materials not only simultaneously display ferroelectricity and ferromagnetism, but also enable magnetic moments to be induced by an external electric field, or electric polarization by a magnetic field. However, synthesizing bulk materials with both long-range orders at room temperature in a single crystalline structure is challenging because conventional ferroelectricity requires closed-shell d0 or s2 cations, whereas ferromagnetic order requires open-shell dn configurations with unpaired electrons. These opposing requirements pose considerable difficulties for atomic-scale design strategies such as magnetic ion substitution into ferroelectrics. One material that exhibits both ferroelectric and magnetic order is BiFeO3, but its cycloidal magnetic structure precludes bulk magnetization and linear magnetoelectric coupling. A solid solution of a ferroelectric and a spin-glass perovskite combines switchable polarization with glassy magnetization, although it lacks long-range magnetic order. Crystal engineering of a layered perovskite has recently resulted in room-temperature polar ferromagnets, but the electrical polarization has not been switchable. Here we combine ferroelectricity and ferromagnetism at room temperature in a bulk perovskite oxide, by constructing a percolating network of magnetic ions with strong superexchange interactions within a structural scaffold

  19. Designing switchable polarization and magnetization at room temperature in an oxide.

    PubMed

    Mandal, P; Pitcher, M J; Alaria, J; Niu, H; Borisov, P; Stamenov, P; Claridge, J B; Rosseinsky, M J

    2015-09-17

    Ferroelectric and ferromagnetic materials exhibit long-range order of atomic-scale electric or magnetic dipoles that can be switched by applying an appropriate electric or magnetic field, respectively. Both switching phenomena form the basis of non-volatile random access memory, but in the ferroelectric case, this involves destructive electrical reading and in the magnetic case, a high writing energy is required. In principle, low-power and high-density information storage that combines fast electrical writing and magnetic reading can be realized with magnetoelectric multiferroic materials. These materials not only simultaneously display ferroelectricity and ferromagnetism, but also enable magnetic moments to be induced by an external electric field, or electric polarization by a magnetic field. However, synthesizing bulk materials with both long-range orders at room temperature in a single crystalline structure is challenging because conventional ferroelectricity requires closed-shell d(0) or s(2) cations, whereas ferromagnetic order requires open-shell d(n) configurations with unpaired electrons. These opposing requirements pose considerable difficulties for atomic-scale design strategies such as magnetic ion substitution into ferroelectrics. One material that exhibits both ferroelectric and magnetic order is BiFeO3, but its cycloidal magnetic structure precludes bulk magnetization and linear magnetoelectric coupling. A solid solution of a ferroelectric and a spin-glass perovskite combines switchable polarization with glassy magnetization, although it lacks long-range magnetic order. Crystal engineering of a layered perovskite has recently resulted in room-temperature polar ferromagnets, but the electrical polarization has not been switchable. Here we combine ferroelectricity and ferromagnetism at room temperature in a bulk perovskite oxide, by constructing a percolating network of magnetic ions with strong superexchange interactions within a structural scaffold

  20. High-Temperature Solid Lubricant Coating

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Edmonds, Brian J.

    2010-01-01

    NASA PS400 is a solid lubricant coating invented for high-temperature tribological applications. This plasma-sprayed coating is a variant of the previously patented PS304 coating, and has been formulated to provide higher density, smoother surface finish, and better dimensional stability. This innovation is a new composite material that provides a means to reduce friction and wear in mechanical components. PS400 is a blend of a nickel-molybdenum binder, chrome oxide hardener, silver lubricant, and barium fluoride/calcium fluoride eutectic lubricant that can either be sprayed or deposited by other means, such as powder metallurgy. The resulting composite material is then finished by grinding and polishing to produce a smooth, self-lubricating surface.

  1. Enhancement of room temperature dislocation-related photoluminescence of electron irradiated silicon

    SciTech Connect

    Xiang Luelue; Li Dongsheng; Jin Lu; Yang Deren; Wang Shuming

    2013-01-21

    In this paper, we have investigated the room temperature dislocation-related photoluminescence of electron irradiated silicon. It is found that high temperature annealing can enhance the D1 line emission measured at room temperature. The abnormal peak shift of D1 line on the dependence of temperatures reveals the reconstruction of D1 luminescence center. It is suggested that the high temperature annealing could cause the transformation of the dislocation-point defect structure, so that the D1 luminescence is enhanced and stabilized.

  2. Flashlamp Pumped, Room Temperature, Nd:YAG Laser Operating at 0.946 Micrometers

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Murray, Keith E.; Walsh, Brian M.

    1998-01-01

    Room temperature operation of flashlamp pumped Nd:YAG at 0.946 micrometers was achieved with a laser rod having undoped ends. Performance was characterized and compared with 1.064 micrometer operation and other quasi four level lasers.

  3. Saccharides as Prospective Immobilizers of Nucleic Acids for Room-Temperature Structural EPR Studies.

    PubMed

    Kuzhelev, Andrey A; Shevelev, Georgiy Yu; Krumkacheva, Olesya A; Tormyshev, Victor M; Pyshnyi, Dmitrii V; Fedin, Matvey V; Bagryanskaya, Elena G

    2016-07-01

    Pulsed dipolar electron paramagnetic resonance (EPR) spectroscopy is a powerful tool for structural studies of biomolecules and their complexes. This method, whose applicability has been recently extended to room temperatures, requires immobilization of the studied biosystem to prevent averaging of dipolar couplings; at the same time, the modification of native conformations by immobilization must be avoided. In this work, we provide first demonstration of room-temperature EPR distance measurements in nucleic acids using saccharides trehalose, sucrose, and glucose as immobilizing media. We propose an approach that keeps structural conformation and unity of immobilized double-stranded DNA. Remarkably, room-temperature electron spin dephasing time of triarylmethyl-labeled DNA in trehalose is noticeably longer compared to previously used immobilizers, thus providing a broader range of available distances. Therefore, saccharides, and especially trehalose, can be efficiently used as immobilizers of nucleic acids, mimicking native conditions and allowing wide range of structural EPR studies at room temperatures. PMID:27320083

  4. High temperature thermoplastic elastomers synthesized by living anionic polymerization in hydrocarbon solvent at room temperature

    DOE PAGESBeta

    Schlegel, Ralf; Williams, Katherine; Voyloy, Dimitry; Steren, Carlos A.; Goodwin, Andrew; Coughlin, E. Bryan; Gido, Samuel; Beiner, Mario; Hong, Kunlun; Kang, Nam -Goo; et al

    2016-03-30

    We present the synthesis and characterization of a new class of high temperature thermoplastic elastomers composed of polybenzofulvene–polyisoprene–polybenzofulvene (FIF) triblock copolymers. All copolymers were prepared by living anionic polymerization in benzene at room temperature. Homopolymerization and effects of additives on the glass transition temperature (Tg) of polybenzofulvene (PBF) were also investigated. Among all triblock copolymers studied, FIF with 14 vol % of PBF exhibited a maximum stress of 14.3 ± 1.3 MPa and strain at break of 1390 ± 66% from tensile tests. The stress–strain curves of FIF-10 and 14 were analyzed by a statistical molecular approach using a nonaffinemore » tube model to estimate the thermoplastic elastomer behavior. Dynamic mechanical analysis showed that the softening temperature of PBF in FIF was 145 °C, much higher than that of thermoplastic elastomers with polystyrene hard blocks. Microphase separation of FIF triblock copolymers was observed by small-angle X-ray scattering, even though long-range order was not achieved under the annealing conditions employed. Additionally, the microphase separation of the resulting triblock copolymers was examined by atomic force microscopy.« less

  5. Direct mineral carbonation of steelmaking slag for CO2 sequestration at room temperature.

    PubMed

    Rushendra Revathy, T D; Palanivelu, K; Ramachandran, A

    2016-04-01

    Rapid increase of CO2 concentration in the atmosphere has forced the international community towards adopting actions to restrain from the impacts of climate change. Moreover, in India, the dependence on fossil fuels is projected to increase in the future, implying the necessity of capturing CO2 in a safe manner. Alkaline solid wastes can be utilized for CO2 sequestration by which its disposal issues in the country could also be met. The present work focuses to study direct mineral carbonation of steelmaking slag (SS) at room temperature and low-pressure conditions (<10 bar). Direct mineral carbonation of SS was carried out in a batch reactor with pure CO2 gas. The process parameters that may influence the carbonation of SS, namely, CO2 gas pressure, liquid to solid ratio (L/S) and reaction time were also studied. The results showed that maximum sequestration of SS was attained in the aqueous route with a capacity of 82 g of CO2/kg (6 bar, L/S ratio of 10 and 3 h). In the gas-solid route, maximum sequestration capacity of about 11.1 g of CO2/kg of SS (3 bar and 3 h) was achieved indicating that aqueous route is the better one under the conditions studied. These findings demonstrate that SS is a promising resource and this approach could be further developed and used for CO2 sequestration in the country. The carbonation process was evidenced using FT-IR, XRD, SEM and TG analysis. PMID:26681331

  6. Ultra-Low-Cost Room Temperature SiC Thin Films

    NASA Technical Reports Server (NTRS)

    Faur, Maria

    1997-01-01

    The research group at CSU has conducted theoretical and experimental research on 'Ultra-Low-Cost Room Temperature SiC Thin Films. The effectiveness of a ultra-low-cost room temperature thin film SiC growth technique on Silicon and Germanium substrates and structures with applications to space solar sells, ThermoPhotoVoltaic (TPV) cells and microelectronic and optoelectronic devices was investigated and the main result of this effort are summarized.

  7. Qualification of room-temperature-curing structural adhesives for use on JPL spacecraft

    NASA Technical Reports Server (NTRS)

    Carpenter, Alain; O'Donnell, Tim

    1989-01-01

    An evaluation is made of the comparative advantages of numerous room temperature-cure structural primers and adhesives applicable to spacecraft structures. The EA 9394 adhesive and BR 127 primer were chosen for use in all primary structure bonding on the Galileo spacecraft, in virtue of adequate room-temperature lap shear and peel strengths and superior mechanical properties above 200 F. EA 9394 also offers superior work life, shelf-life, and storage properties, by comparison with the EA 934 alternative.

  8. Room-temperature single-photon sources based on nanocrystal fluorescence in photonic/plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Lukishova, S. G.; Winkler, J. M.; Bissell, L. J.; Mihaylova, D.; Liapis, Andreas C.; Shi, Z.; Goldberg, D.; Menon, V. M.; Boyd, R. W.; Chen, G.; Prasad, P.

    2014-10-01

    Results are presented here towards robust room-temperature SPSs based on fluorescence in nanocrystals: colloidal quantum dots, color-center diamonds and doped with trivalent rare-earth ions (TR3+). We used cholesteric chiral photonic bandgap and Bragg-reflector microcavities for single emitter fluorescence enhancement. We also developed plasmonic bowtie nanoantennas and 2D-Si-photonic bandgap microcavities. The paper also provides short outlines of other technologies for room-temperature single-photon sources.

  9. Spreading of lithium on a stainless steel surface at room temperature

    NASA Astrophysics Data System (ADS)

    Skinner, C. H.; Capece, A. M.; Roszell, J. P.; Koel, B. E.

    2016-01-01

    Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. The spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 μm/day under ultrahigh vacuum conditions. Separate experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (Edes = 1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (Edes = 2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium-lithium bonding.

  10. Colossal Room-Temperature Electrocaloric Effect in Ferroelectric Polymer Nanocomposites Using Nanostructured Barium Strontium Titanates.

    PubMed

    Zhang, Guangzu; Zhang, Xiaoshan; Yang, Tiannan; Li, Qi; Chen, Long-Qing; Jiang, Shenglin; Wang, Qing

    2015-07-28

    The electrocaloric effect (ECE) refers to conversion of thermal to electrical energy of polarizable materials and could form the basis for the next-generation refrigeration and power technologies that are highly efficient and environmentally friendly. Ferroelectric materials such as ceramic and polymer films exhibit large ECEs, but each of these monolithic materials has its own limitations for practical cooling applications. In this work, nanosized barium strontium titanates with systematically varied morphologies have been prepared to form polymer nanocomposites with the ferroelectric polymer matrix. The solution-processed polymer nanocomposites exhibit an extraordinary room-temperature ECE via the synergistic combination of the high breakdown strength of a ferroelectric polymer matrix and the large change of polarization with temperature of ceramic nanofillers. It is found that a sizable ECE can be generated under both modest and high electric fields, and further enhanced greatly by tailoring the morphology of the ferroelectric nanofillers such as increasing the aspect ratio of the nanoinclusions. The effect of the geometry of the nanofillers on the dielectric permittivity, polarization, breakdown strength, ECE and crystallinity of the ferroelectric polymer has been systematically investigated. Simulations based on the phase-field model have been carried out to substantiate the experimental results. With the remarkable cooling energy density and refrigerant capacity, the polymer nanocomposites are promising for solid-state cooling applications. PMID:26132841

  11. Room-temperature silver-containing liquid metal salts with nitrate anions.

    PubMed

    Schaltin, Stijn; Brooks, Neil R; Sniekers, Jeroen; Depuydt, Daphne; Van Meervelt, Luc; Binnemans, Koen; Fransaer, Jan

    2013-11-21

    The synthesis, structural, thermal and electrochemical properties of fluorine-free silver-containing ionic liquids are presented. The ionic liquid cations are formed by a silver(i) ion surrounded by two 1-alkylimidazole ligands, with the counter anions being nitrate ions. Depending on the alkyl chain length, the complexes were found to be liquids at room temperature or melting slightly above this. For the solid compounds it was possible to elucidate the structure by single crystal X-ray analysis. The ionic liquids are electroactive, have good mass transport properties and can be used for the electrodeposition of silver at high current densities. The thermal properties and stability of these compounds were tested by differential scanning calorimetry and thermogravimetric analysis. The viscosity of the ionic liquids follows a Vogel-Tamman-Fulcher relationship as a function of temperature. The electrochemical properties of the complexes were tested by cyclic voltammetry and the resulting electrodeposits were examined using scanning electron microscopy and atomic force microscopy. PMID:24097139

  12. Spreading of lithium on a stainless steel surface at room temperature

    SciTech Connect

    Skinner, C. H.; Capece, A. M.; Roszell, J. P.; Koel, B. E.

    2015-11-10

    Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. Here, the spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 μm/day under ultrahigh vacuum conditions. Separate experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (Edes = 1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (Edes = 2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium lithium bonding.

  13. Spreading of lithium on a stainless steel surface at room temperature

    DOE PAGESBeta

    Skinner, C. H.; Capece, A. M.; Roszell, J. P.; Koel, B. E.

    2015-11-10

    Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. Here, the spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 μm/day under ultrahigh vacuum conditions. Separatemore » experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (Edes = 1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (Edes = 2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium lithium bonding.« less

  14. Spreading of lithium on a stainless steel surface at room temperature

    SciTech Connect

    Skinner, C. H.; Capece, A. M.; Roszell, J. P.; Koel, B. E.

    2016-01-01

    Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. The spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 mu m/day under ultrahigh vacuum conditions. Separate experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (E-des = 1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (E-des = 2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium lithium bonding. (C) 2015 Elsevier B.V. All rights reserved.

  15. Evolution of Dust Structures from Room to Cryogenic Temperatures

    SciTech Connect

    Antipov, S. N.; Asinovskii, E. I.; Kirillin, A. V.; Markovets, V. V.; Petrov, O. F.; Fortov, V. E.

    2008-09-07

    In this work dusty plasma of dc glow discharge at the temperatures in the range of 4.2-300 K was experimentally and numerically investigated. As it was shown in the experiments, the deep cooling of discharge tube walls leads to dramatic change of dusty plasma properties. In particular, sufficient increase of dust particle kinetic temperature (by about an order) and dust density (by several orders) was observed at low (cryogenic) temperatures. At 4.2 K, this can lead to the forming of a super dense dust structures with novel properties. Numerical simulations of charging process, dust charge fluctuation and screening of dust particle charge in plasma were made in dependence with the neutral gas temperature and dust density. The main attention was given to proper ion-atom collision analysis that allows us to investigate mechanisms of dust structure transformation observed in the cryogenic experiments.

  16. Room-temperature calorimeter for x-ray free-electron lasers

    NASA Astrophysics Data System (ADS)

    Tanaka, T.; Kato, M.; Saito, N.; Tono, K.; Yabashi, M.; Ishikawa, T.

    2015-09-01

    We have developed a room-temperature calorimeter for absolute radiant power measurements of x-ray free-electron lasers. This room-temperature calorimeter is an electrical substitution device based on the equivalence of electrical and radiant heating. Consequently, the measured radiant powers are traceable to electrical standards, i.e., the International System Units (SI). We demonstrated the performance of the room-temperature calorimeter by electrical power measurements (offline tests). In the offline tests, the room-temperature calorimeter was proven to be able to measure external powers up to at least 6.9 mW, which exceeds the upper limit (˜4 mW) of a cryogenic radiometer (the primary standard detector in Japan). In addition, measurement uncertainties of the room-temperature calorimeter were evaluated to be less than 1.0%, which is adequate for the radiant power measurements of x-ray free-electron lasers. An indirect comparison with the cryogenic radiometer was performed using a synchrotron radiation source to confirm the validity of the absolute radiant powers measured with the room-temperature calorimeter. The absolute radiant powers measured by the calorimeter agreed with those measured by the cryogenic radiometer within 0.6%, which is less than the relative standard uncertainty of the comparison (1.0%).

  17. Room-temperature calorimeter for x-ray free-electron lasers

    SciTech Connect

    Tanaka, T. Kato, M.; Saito, N.; Tono, K.; Yabashi, M.; Ishikawa, T.

    2015-09-15

    We have developed a room-temperature calorimeter for absolute radiant power measurements of x-ray free-electron lasers. This room-temperature calorimeter is an electrical substitution device based on the equivalence of electrical and radiant heating. Consequently, the measured radiant powers are traceable to electrical standards, i.e., the International System Units (SI). We demonstrated the performance of the room-temperature calorimeter by electrical power measurements (offline tests). In the offline tests, the room-temperature calorimeter was proven to be able to measure external powers up to at least 6.9 mW, which exceeds the upper limit (∼4 mW) of a cryogenic radiometer (the primary standard detector in Japan). In addition, measurement uncertainties of the room-temperature calorimeter were evaluated to be less than 1.0%, which is adequate for the radiant power measurements of x-ray free-electron lasers. An indirect comparison with the cryogenic radiometer was performed using a synchrotron radiation source to confirm the validity of the absolute radiant powers measured with the room-temperature calorimeter. The absolute radiant powers measured by the calorimeter agreed with those measured by the cryogenic radiometer within 0.6%, which is less than the relative standard uncertainty of the comparison (1.0%)

  18. Ultraviolet stimulated emission from high-temperature-annealed MgO microcrystals at room temperature

    NASA Astrophysics Data System (ADS)

    Soma, Haruka; Uenaka, Yuki; Asahara, Akifumi; Suemoto, Tohru; Uchino, Takashi

    2015-01-01

    Research on semiconductor nanowires underlies the development of the miniaturization of laser devices with low cost and low energy consumption. In general, nanowire lasers are made of direct band gap semiconductors, e.g., GaN, ZnO and CdS, and their band-edge emissions are used to achieve optically pumped laser emission. In addition to the existing class of nanowire lasers, we here show that air-annealed micrometer-sized MgO cubic crystals with well-defined facets exhibit room-temperature stimulated emission at 394 nm under pulsed laser pumping at ˜350 nm. Surface midgap states are assumed to be responsible for the excitation and emission processes. The present findings will not only provide opportunities for the development of miniaturized lasers composed of insulating oxides, but will also open up functionality in various families of cubic crystalline materials.

  19. Fast synthesis of high-quality reduced graphene oxide at room temperature under light exposure

    NASA Astrophysics Data System (ADS)

    Some, Surajit; Kim, Sungjin; Samanta, Khokan; Kim, Youngmin; Yoon, Yeoheung; Park, Younghun; Lee, Sae Mi; Lee, Keunsik; Lee, Hyoyoung

    2014-09-01

    An approach of presenting new reducing reagents, sodium-benzophenone (Na-B) or Na-B in the presence of the hydrazine (Na-B-H) system under light exposure could produce rGOs with/without N-doping at room temperature in both the solution phase and on a solid substrate. Benzophenone activated those solutions acting as a photosensitizer under light. It was assumed that the newly generated radical anions with electrons from Na-B under light can reduce GO to rGO sheets (rGONa-B1). In addition, the Na-B-H system can allow a higher degree of reduction with the doping of nitrogen atoms by the introduction of hydrazine to produce radical anions and electrons with a sodium hydrazide complex, which helps decrease the sheet resistance of the as-made rGONa-B-H2. The excellent properties (very low oxygen content (C/O ~16.2), and low sheet resistance (~130 Ω square-1)) of the rGOs were confirmed by XPS, XRD, IR, Raman spectroscopy, TGA, wettability, and sheet resistance measurements. High-quality rGO films on flexible substrates could be prepared by directly immersing the GO films in these solutions for several minutes.An approach of presenting new reducing reagents, sodium-benzophenone (Na-B) or Na-B in the presence of the hydrazine (Na-B-H) system under light exposure could produce rGOs with/without N-doping at room temperature in both the solution phase and on a solid substrate. Benzophenone activated those solutions acting as a photosensitizer under light. It was assumed that the newly generated radical anions with electrons from Na-B under light can reduce GO to rGO sheets (rGONa-B1). In addition, the Na-B-H system can allow a higher degree of reduction with the doping of nitrogen atoms by the introduction of hydrazine to produce radical anions and electrons with a sodium hydrazide complex, which helps decrease the sheet resistance of the as-made rGONa-B-H2. The excellent properties (very low oxygen content (C/O ~16.2), and low sheet resistance (~130 Ω square-1)) of the r

  20. Entanglement and Bell's inequality violation above room temperature in metal carboxylates.

    SciTech Connect

    Souza, A M; Soares-Pinto, D O; Sarthour, R S; Oliveira, I S; Reis, Mario S; Brandao, Paula; Moreira Dos Santos, Antonio F

    2009-01-01

    In the present work we show that a particular family of materials, the metal carboxylates, may have entangled states up to very high temperatures. From magnetic-susceptibility measurements, we have estimated the critical temperature below which entanglement exists in the copper carboxylate {Cu-2(O2CH)(4)}{Cu(O2CH)(2)(2-methylpyridine)(2)}, and we have found this to be above room temperature (T-e similar to 630 K). Furthermore, the results show that the system remains maximally entangled until close to similar to 100 K and the Bell's inequality is violated up to nearly room temperature (similar to 290 K).

  1. Low threshold interband cascade lasers operating above room temperature

    NASA Technical Reports Server (NTRS)

    Hill, C. J.; Yang, B.; Yang, R. Q.

    2003-01-01

    Mid-IR type-II interband cascade lasers were demonstrated in pulsed mode at temperatures up to 325 K and in continuous mode up to 200 K. At 80 K, the threshold current density was 8.9 A/cm2 and a cw outpout power of 140 mW/facet was obtained.

  2. A Fluorinated Ligand Enables Room-Temperature and Regioselective Pd-Catalyzed Fluorination of Aryl Triflates and Bromides.

    PubMed

    Sather, Aaron C; Lee, Hong Geun; De La Rosa, Valentina Y; Yang, Yang; Müller, Peter; Buchwald, Stephen L

    2015-10-21

    A new biaryl monophosphine ligand (AlPhos, L1) allows for the room-temperature Pd-catalyzed fluorination of a variety of activated (hetero)aryl triflates. Furthermore, aryl triflates and bromides that are prone to give mixtures of regioisomeric aryl fluorides with Pd-catalysis can now be converted to the desired aryl fluorides with high regioselectivity. Analysis of the solid-state structures of several Pd(II) complexes, as well as density functional theory (DFT) calculations, shed light on the origin of the enhanced reactivity observed with L1. PMID:26413908

  3. One-pot room-temperature conversion of cyclohexane to adipic acid by ozone and UV light.

    PubMed

    Hwang, Kuo Chu; Sagadevan, Arunachalam

    2014-12-19

    Nitric acid oxidation of cyclohexane accounts for ~95% of the worldwide adipic acid production and is also responsible for ~5 to 8% of the annual worldwide anthropogenic emission of the ozone-depleting greenhouse gas nitrous oxide (N2O). Here we report a N2O-free process for adipic acid synthesis. Treatment of neat cyclohexane, cyclohexanol, or cyclohexanone with ozone at room temperature and 1 atmosphere of pressure affords adipic acid as a solid precipitate. Addition of acidic water or exposure to ultraviolet (UV) light irradiation (or a combination of both) dramatically enhances the oxidative conversion of cyclohexane to adipic acid. PMID:25525242

  4. Room-temperature quantum bit storage exceeding 39 minutes using ionized donors in silicon-28.

    PubMed

    Saeedi, Kamyar; Simmons, Stephanie; Salvail, Jeff Z; Dluhy, Phillip; Riemann, Helge; Abrosimov, Nikolai V; Becker, Peter; Pohl, Hans-Joachim; Morton, John J L; Thewalt, Mike L W

    2013-11-15

    Quantum memories capable of storing and retrieving coherent information for extended times at room temperature would enable a host of new technologies. Electron and nuclear spin qubits using shallow neutral donors in semiconductors have been studied extensively but are limited to low temperatures (≲10 kelvin); however, the nuclear spins of ionized donors have the potential for high-temperature operation. We used optical methods and dynamical decoupling to realize this potential for an ensemble of phosphorous-31 donors in isotopically purified silicon-28 and observed a room-temperature coherence time of over 39 minutes. We further showed that a coherent spin superposition can be cycled from 4.2 kelvin to room temperature and back, and we report a cryogenic coherence time of 3 hours in the same system. PMID:24233718

  5. Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite

    PubMed Central

    Lin, Aigu L.; Rodrigues, J. N. B.; Su, Chenliang; Milletari, M.; Loh, Kian Ping; Wu, Tom; Chen, Wei; Neto, A. H. Castro; Adam, Shaffique; Wee, Andrew T. S.

    2015-01-01

    Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m2/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite. PMID:26100970

  6. A study on the characteristics of CO oxidation at room temperature by metallic Pt.

    PubMed

    Seo, Phil Won; Choi, Hyun Jin; Hong, Suk In; Hong, Sung Chang

    2010-06-15

    Various experiments and analysis were conducted in order to manufacture a catalyst that could very efficiently oxidize carbon monoxide at room temperature and also to identify the relevant factors influencing the oxidation reaction. Pt/TiO(2) catalyst can increase the oxidizing capability of CO at low temperature and room temperature by reduction. In FT-IR experiments, the catalyst that displayed excellent activity was capable of efficiently oxidizing CO to CO(2) using atmospheric oxygen. Based on the results of XPS analysis, we found that the reduced catalyst changed the platinum's oxidation value to Pt(+2) and Pt(+0). Through the O(2)-reoxidation experiments, the catalyst, which consisted of non-stoichiometric platinum oxidized species, displayed an excellent ability to accept oxygen. In this study, the Pt/TiO(2) catalyst was able to very efficiently oxidize CO at low temperature and room temperature even with a minute quantity of platinum. PMID:20207073

  7. Biomedical application of metalloporphyrins room-temperature phosphorescence

    NASA Astrophysics Data System (ADS)

    Savitsky, Alexander P.

    1993-05-01

    Biological specimens are characterized by high light-scattering and background fluorescence which cause decrease in sensitivity of immunoassays. These unfavorable effects can be minimized by selecting a label with high absolute sensitivity, appropriate excitation and emission wavelengths, and time-resolved mode of measurements. This can be achieved by the use of metalloporphyrin labels, microsecond logic for discrimination of scattered light and background fluorescence which arises in optical elements, cells, solvents, and samples. The intensity of metalloporphyrin phosphorescence depends to a great extent on pH. Nonionic and cationic micelles have a strong effect on the phosphorescence quantum yield of Pd- coproporphyrin. Under optimum conditions Pd-coproporphyrin can be detected at a concentration of 10-13M by using modified Arcus 1230 (Wallac, Finland). On the basis of these results a novel class of luminescent labels --phosphorescent metalloporphyrins -- was applied to immunoassays. Pd- and Pt-coproporphyrins were used for the covalent labeling of antibodies and antigens. Special derivatives of a porphyrin with activated side chain were synthesized. Techniques for covalent coupling of porphyrins and their metal derivatives with proteins were developed as well as methods for purification of conjugates. A solid-phase time-resolved porphyrin phosphorescence immunoassay test was developed. The well known `sandwich' and competition techniques are compatible with the proposed method. Two or more metalloporphyrins with distinguishable phosphorescent parameters may be used for the simultaneous determining of several antigens in one sample.

  8. Effects of various room temperatures on terahertz radiation via optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Huang, Nan; Liu, Hongjun; Sun, Qibing

    2014-06-01

    A terahertz (THz)-wave parametric oscillator (TPO) pumped by a stable and single-longitudinal mode Q-switched Nd:YAG laser under various room temperatures is demonstrated. It is based on a cavity TPO architecture allowing stable single-resonance operation and low oscillation threshold. The output results, including the effects of the room temperature on this wavelength-agile TPO with a MgO:LiNbO3 crystal, indicate that the performance of TPO under the lower temperature is better. We obtain a widely tunable THz-wave source in the range 104 to 226 μm via tuning the cavity flexibly under different room temperatures. The peak power of the THz wave reaches 220 mW at the wavelength of 146.2 μm when the room temperature is 20°C. The peak power of the THz wave decreases to 48 mW when the room temperature rises from 20°C to 25°C.

  9. Can doping graphite trigger room temperature superconductivity? Evidence for granular high-temperature superconductivity in water-treated graphite powder.

    PubMed

    Scheike, T; Böhlmann, W; Esquinazi, P; Barzola-Quiquia, J; Ballestar, A; Setzer, A

    2012-11-14

    Granular superconductivity in powders of small graphite grains (several tens of micrometers) is demonstrated after treatment with pure water. The temperature, magnetic field and time dependence of the magnetic moment of the treated graphite powder provides evidence for the existence of superconducting vortices with some similarities to high-temperature granular superconducting oxides but even at temperatures above 300 K. Room temperature superconductivity in doped graphite or at its interfaces appears to be possible. PMID:22949348

  10. Electrochemical study of hydrogen permeation through tungsten near room temperature

    NASA Astrophysics Data System (ADS)

    Manhard, A.; Kapser, S.; Gao, L.

    2015-08-01

    We used an electrochemical double cell to study permeation of hydrogen through a 3.5 μm thick sputter-deposited tungsten layer on a 25 μm thick palladium support. The temperature dependence of the steady-state permeation current was studied in the range from 266 to 333 K for a constant charging potential on the entry side and zero hydrogen concentration on the exit side of the sample foil. We found that the data is best described by a sum of two Arrhenius terms. We postulate that the higher activation energy of 0.86 ± 0.07 eV corresponds to permeation through bulk grains and may approach the literature value of 1.43 ± 0.26 eV for even higher temperature. For the second, lower activation energy of 0.39 ± 0.03 eV, we currently consider fast diffusion along grain boundaries the most likely explanation.

  11. Room temperature detection of individual molecular physisorption using suspended bilayer graphene.

    PubMed

    Sun, Jian; Muruganathan, Manoharan; Mizuta, Hiroshi

    2016-04-01

    Detection of individual molecular adsorption, which represents the ultimate resolution of gas sensing, has rarely been realized with solid-state devices. So far, only a few studies have reported detection of individual adsorption by measuring the variation of electronic transport stemming from the charge transfer of adsorbate. We report room-temperature detection of the individual physisorption of carbon dioxide molecules with suspended bilayer graphene (BLG) based on a different mechanism. An electric field introduced by applying back-gate voltage is used to effectively enhance the adsorption rate. A unique device architecture is designed to induce tensile strain in the BLG to prevent its mechanical deflection onto the substrate by electrostatic force. Despite the negligible charge transfer from a single physisorbed molecule, it strongly affects the electronic transport in suspended BLG by inducing charged impurity, which can shut down part of the conduction of the BLG with Coulomb impurity scattering. Accordingly, we can detect each individual physisorption as a step-like resistance change with a quantized value in the BLG. We use density functional theory simulation to theoretically estimate the possible resistance response caused by Coulomb scattering of one adsorbed CO2 molecule, which is in agreement with our measurement. PMID:27152344

  12. Room temperature detection of individual molecular physisorption using suspended bilayer graphene

    PubMed Central

    Sun, Jian; Muruganathan, Manoharan; Mizuta, Hiroshi

    2016-01-01

    Detection of individual molecular adsorption, which represents the ultimate resolution of gas sensing, has rarely been realized with solid-state devices. So far, only a few studies have reported detection of individual adsorption by measuring the variation of electronic transport stemming from the charge transfer of adsorbate. We report room-temperature detection of the individual physisorption of carbon dioxide molecules with suspended bilayer graphene (BLG) based on a different mechanism. An electric field introduced by applying back-gate voltage is used to effectively enhance the adsorption rate. A unique device architecture is designed to induce tensile strain in the BLG to prevent its mechanical deflection onto the substrate by electrostatic force. Despite the negligible charge transfer from a single physisorbed molecule, it strongly affects the electronic transport in suspended BLG by inducing charged impurity, which can shut down part of the conduction of the BLG with Coulomb impurity scattering. Accordingly, we can detect each individual physisorption as a step-like resistance change with a quantized value in the BLG. We use density functional theory simulation to theoretically estimate the possible resistance response caused by Coulomb scattering of one adsorbed CO2 molecule, which is in agreement with our measurement. PMID:27152344

  13. Singular robust room-temperature spin response from topological Dirac fermions.

    PubMed

    Zhao, Lukas; Deng, Haiming; Korzhovska, Inna; Chen, Zhiyi; Konczykowski, Marcin; Hruban, Andrzej; Oganesyan, Vadim; Krusin-Elbaum, Lia

    2014-06-01

    Topological insulators are a class of solids in which the non-trivial inverted bulk band structure gives rise to metallic surface states that are robust against impurity scattering. In three-dimensional (3D) topological insulators, however, the surface Dirac fermions intermix with the conducting bulk, thereby complicating access to the low-energy (Dirac point) charge transport or magnetic response. Here we use differential magnetometry to probe spin rotation in the 3D topological material family (Bi2Se3, Bi2Te3 and Sb2Te3). We report a paramagnetic singularity in the magnetic susceptibility at low magnetic fields that persists up to room temperature, and which we demonstrate to arise from the surfaces of the samples. The singularity is universal to the entire family, largely independent of the bulk carrier density, and consistent with the existence of electronic states near the spin-degenerate Dirac point of the 2D helical metal. The exceptional thermal stability of the signal points to an intrinsic surface cooling process, probably of thermoelectric origin, and establishes a sustainable platform for the singular field-tunable Dirac spin response. PMID:24836736

  14. Room-temperature magnetic properties of SiC based nanowires synthesized via microwave heating method

    NASA Astrophysics Data System (ADS)

    Liu, Song; Wang, Jigang

    2016-07-01

    Two kinds of ferromagnetic SiC based nanowires with and without Ni catalyst were successfully synthesized by employing microwave heating method. The comprehensive characterizations and vibrating sample magnetometer (VSM) have been applied to investigate the micro-structures and magnetic properties of as-grown nanowires. For the nanowires synthesized without using Ni catalyst, the diameters and lengths are in the range of 20-60 nm and dozens of micrometers, respectively. Particularly, the results of transmission electron microscopy (TEM) show that the nanowires consist of SiC core and SiOx shell. The SiC/SiOx coaxial nanowires exhibit room-temperature ferromagnetism with saturation magnetization (Ms) of 0.2 emu/g. As to the nanowires obtained using Ni catalyst, the scanning electron microscopy (SEM) results indicate that the Ni catalyzed nanowires have a nano-particle attached on the tip and a uniform diameter of approximately 50 nm. The vapor-liquid-solid (VLS) growth mechanism can be used to explain the formation of the Ni catalyzed nanowires. The detection result of VSM indicates that the Ni catalyzed nanowires possess the paramagnetism and the ferromagnetism, simultaneously. The enhancement of the ferromagnetism, compared with the SiC/SiOx coaxial nanowires, could be attributed to the Ni2Si and NiSi phases.

  15. Radiation defect dynamics in Si at room temperature studied by pulsed ion beams

    SciTech Connect

    Wallace, J. B.; Myers, M. T.; Charnvanichborikarn, S.; Bayu Aji, L. B.; Kucheyev, S. O.; Shao, L.

    2015-10-07

    The evolution of radiation defects after the thermalization of collision cascades often plays the dominant role in the formation of stable radiation disorder in crystalline solids of interest to electronics and nuclear materials applications. Here, we explore a pulsed-ion-beam method to study defect interaction dynamics in Si crystals bombarded at room temperature with 500 keV Ne, Ar, Kr, and Xe ions. The effective time constant of defect interaction is measured directly by studying the dependence of lattice disorder, monitored by ion channeling, on the passive part of the beam duty cycle. The effective defect diffusion length is revealed by the dependence of damage on the active part of the beam duty cycle. Results show that the defect relaxation behavior obeys a second order kinetic process for all the cases studied, with a time constant in the range of ∼4–13 ms and a diffusion length of ∼15–50 nm. Both radiation dynamics parameters (the time constant and diffusion length) are essentially independent of the maximum instantaneous dose rate, total ion dose, and dopant concentration within the ranges studied. However, both the time constant and diffusion length increase with increasing ion mass. This demonstrates that the density of collision cascades influences not only defect production and annealing efficiencies but also the defect interaction dynamics.

  16. Thin-walled boron nitride microtubes exhibiting intense band-edge UV emission at room temperature.

    PubMed

    Huang, Yang; Bando, Yoshio; Tang, Chengchun; Zhi, Chunyi; Terao, Takeshi; Dierre, Benjamin; Sekiguchi, Takashi; Golberg, Dmitri

    2009-02-25

    Boron nitride (BN) microtubes were synthesized in a vertical induction furnace using Li(2)CO(3) and B reactants. Their structures and morphologies were investigated using x-ray diffraction, scanning and transmission electron microscopy, and energy-dispersive x-ray spectroscopy. The microtubes have diameters of 1-3 microm, lengths of up to hundreds of micrometers, and well-structured ultrathin walls only approximately 50 nm thick. A mechanism combining the vapor-liquid-solid (VLS) and template self-sacrificing processes is proposed to explain the formation of these novel one-dimensional microstructures, in which the Li(2)O-B(2)O(3) eutectic reaction plays an important role. Cathodoluminescence studies show that even at room temperature the thin-walled BN microtubes can possess an intense band-edge emission at approximately 216.5 nm, which is distinct compared with other BN nanostructures. The study suggests that the thin-walled BN microtubes should be promising for constructing compact deep UV devices and find potential applications in microreactors and microfluidic and drug delivery systems. PMID:19417466

  17. Frequency tunable electronic sources working at room temperature in the 1 to 3 THz band

    NASA Astrophysics Data System (ADS)

    Maestrini, Alain; Mehdi, Imran; Siles, José V.; Lin, Robert; Lee, Choonsup; Chattopadhyay, Goutam; Pearson, John; Siegel, Peter

    2012-10-01

    Compact, room temperature terahertz sources are much needed in the 1 to 3 THz band for developing multi-pixel heterodyne receivers for astrophysics and planetary science or for building short-range high spatial resolution THz imaging systems able to see through low water content and non metallic materials, smoke or dust for a variety of applications ranging from the inspection of art artifacts to the detection of masked or concealed objects. All solid-sate electronic sources based on a W-band synthesizer followed by a high-power W-band amplifier and a cascade of Schottky diode based THz frequency multipliers are now capable of producing more than 1 mW at 0.9THz, 50 μW at 2 THz and 18 μW at 2.6 THz without the need of any cryogenic system. These sources are frequency agile and have a relative bandwidth of 10 to 15%, limited by the high power W-band amplifiers. The paper will present the latest developments of this technology and its perspective in terms of frequency range, bandwidth and power.

  18. Fiber-optic multiband radiometer for online measurements of near room temperature and emissivity.

    PubMed

    Uman, Igor; Katzir, Abraham

    2006-02-01

    A multiband infrared fiber-optic radiometer was developed for online near room temperature and emissivity measurements. Real time measurements were carried out on gray and selective bodies at near room temperature. The mean accuracy obtained for the body temperature was roughly 1 degrees C and for emissivity was roughly 0.03. The radiometer is capable of performing measurements without prior knowledge of the body emissivity. Incorporation of fiber optics allows one to perform measurements without a clear line of sight between the radiometer and the body. This radiometer will have important applications in biology, electronics, and other areas. PMID:16480197

  19. Direct observation of a highly spin-polarized organic spinterface at room temperature

    PubMed Central

    Djeghloul, F.; Ibrahim, F.; Cantoni, M.; Bowen, M.; Joly, L.; Boukari, S.; Ohresser, P.; Bertran, F.; Le Fèvre, P.; Thakur, P.; Scheurer, F.; Miyamachi, T.; Mattana, R.; Seneor, P.; Jaafar, A.; Rinaldi, C.; Javaid, S.; Arabski, J.; Kappler, J. -P; Wulfhekel, W.; Brookes, N. B.; Bertacco, R.; Taleb-Ibrahimi, A.; Alouani, M.; Beaurepaire, E.; Weber, W.

    2013-01-01

    Organic semiconductors constitute promising candidates toward large-scale electronic circuits that are entirely spintronics-driven. Toward this goal, tunneling magnetoresistance values above 300% at low temperature suggested the presence of highly spin-polarized device interfaces. However, such spinterfaces have not been observed directly, let alone at room temperature. Thanks to experiments and theory on the model spinterface between phthalocyanine molecules and a Co single crystal surface, we clearly evidence a highly efficient spinterface. Spin-polarised direct and inverse photoemission experiments reveal a high degree of spin polarisation at room temperature at this interface. We measured a magnetic moment on the molecule's nitrogen π orbitals, which substantiates an ab-initio theoretical description of highly spin-polarised charge conduction across the interface due to differing spinterface formation mechanisms in each spin channel. We propose, through this example, a recipe to engineer simple organic-inorganic interfaces with remarkable spintronic properties that can endure well above room temperature. PMID:23412079

  20. Fundamental Properties of TBAF Clathrate for Usage as a Latent Heat Storage at a Room Temperature

    NASA Astrophysics Data System (ADS)

    Mizushima, Takanari; Kawamura, Hiroshi; Takao, Shingo; Yabe, Akira

    For promotion of further energy conservation, development of a coolant with a higher heat capacity regulated around a room temperature is strongly required. As a candidate of such a new coolant, we employ the clathrate hydrate, i.e., a mixture of Tetra n-butyl ammonium fluoride (TBAF) and water. This clathrate hydrate is composed of the micro crystals with an order of 100 μm in dimension. It retains fluidity and melting point at a room temperature of about 25 °C. Moreover, the melting point is able to be controlled between 25 °C and 0 °C by changing the concentration of TBAF. The temperature can be regulated by its latent heat at the melting point. Characteristics such as the latent heat and the crystal structure of the clathrate have been experimentally obtained to confirm the feasibility for its usage as the latent heat storage around a room temperature.

  1. Room-temperature ferroelectricity of SrTiO{sub 3} films modulated by cation concentration

    SciTech Connect

    Yang, Fang; Zhang, Qinghua; Yang, Zhenzhong; Gu, Junxing; Liang, Yan; Li, Wentao; Wang, Weihua; Jin, Kuijuan; Gu, Lin; Guo, Jiandong

    2015-08-24

    The room-temperature ferroelectricity of SrTiO{sub 3} is promising for oxide electronic devices controlled by multiple fields. An effective way to control the ferroelectricity is highly demanded. Here, we show that the off-centered antisite-like defects in SrTiO{sub 3} films epitaxially grown on Si (001) play the determinative role in the emergence of room-temperature ferroelectricity. The density of these defects changes with the film cation concentration sensitively, resulting in a varied coercive field of the ferroelectric behavior. Consequently, the room-temperature ferroelectricity of SrTiO{sub 3} films can be effectively modulated by tuning the temperature of metal sources during the molecular beam epitaxy growth. Such an easy and reliable modulation of the ferroelectricity enables the flexible engineering of multifunctional oxide electronic devices.

  2. Proposal of a general scheme to obtain room-temperature spin polarization in asymmetric antiferromagnetic semiconductors

    NASA Astrophysics Data System (ADS)

    Li, Xingxing; Wu, Xiaojun; Li, Zhenyu; Yang, Jinlong

    2015-09-01

    Exploring magnetic semiconductors is one of the most important questions for spintronic applications. Although various solutions, such as dilute magnetic semiconductors, have been proposed, a practical spintronic device working at room temperature has not been realized. The key to address this issue is to find magnetic materials with both room-temperature magnetic ordering and large spin polarization around the Fermi energy level. Here, we predict a new concept of asymmetric antiferromagnetic (AFM) semiconductors (AAFMSs) with both features. The high temperature magnetic ordering originates from the AFM coupling between different transition metal ions with strong super-exchange interaction, whereas the large spin polarization around the Fermi energy level owes to d orbital mismatch among these ions. Through first-principles calculations, a family of double perovskites A2Cr M O6 (A =Ca ,Sr ,Ba , and M =Ru ,Os ) are predicted to be AAFMSs. This paper provides a way for developing spintronic devices working at room temperature.

  3. Buffer-enhanced room-temperature growth and characterization of epitaxial ZnO thin films

    SciTech Connect

    Sasaki, Atsushi; Hara, Wakana; Matsuda, Akifumi; Tateda, Norihiro; Otaka, Sei; Akiba, Shusaku; Saito, Keisuke; Yodo, Tokuo; Yoshimoto, Mamoru

    2005-06-06

    The room-temperature epitaxial growth of ZnO thin films on NiO buffered sapphire (0001) substrate was achieved by using the laser molecular-beam-epitaxy method. The obtained ZnO films had the ultrasmooth surface reflecting the nanostepped structure of the sapphire substrate. The crystal structure at the surface was investigated in situ by means of coaxial impact-collision ion scattering spectroscopy. It was proved that the buffer-enhanced epitaxial ZnO thin films grown at room temperature had +c polarity, while the polarity of high-temperature grown ZnO thin films on the sapphire was -c. Photoluminescence spectra at room temperature were measured for the epitaxial ZnO films, showing only the strong ultraviolet emission near 380 nm.

  4. Rectifying characteristic in all-perovskite oxide film p-n junction with room temperature ferromagnetism

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Tanaka, Hidekazu; Kawai, Tomoji

    2002-06-01

    We fabricated an all-perovskite oxide p-n junction comprised of hole-doped (p-) manganite La0.9Ba0.1MnO3 and electron-doped (n-) titanate Sr0.99La0.01TiO3 films. The junction showed good rectifying properties at both room temperature and low temperature in a simple structure without inserting an insulating layer. By optimizing junction fabrication conditions, a thin La0.9Ba0.1MnO3 layer in the junction exhibited room temperature ferromagnetism and metallic conduction, which may be modulated by carrier injection from the n-type layer under an electric field. These results indicate that this p-n junction may be developed into functional, strongly correlated electronic devices able to work at room temperature.

  5. Dispersion interactions in room-temperature ionic liquids: results from a non-empirical density functional.

    PubMed

    Kohanoff, Jorge; Pinilla, Carlos; Youngs, Tristan G A; Artacho, Emilio; Soler, José M

    2011-10-21

    The role of dispersion or van de Waals (VDW) interactions in imidazolium-based room-temperature ionic liquids is studied within the framework of density functional theory, using a recently developed non-empirical functional [M. Dion, H. Rydberg, E. Schröder, D. C. Langreth, and B. I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004)], as efficiently implemented in the SIESTA code [G. Román-Pérez and J. M. Soler, Phys. Rev. Lett. 103, 096102 (2009)]. We present results for the equilibrium structure and lattice parameters of several crystalline phases, finding a general improvement with respect to both the local density (LDA) and the generalized gradient approximations (GGA). Similar to other systems characterized by VDW bonding, such as rare gas and benzene dimers as well as solid argon, equilibrium distances and volumes are consistently overestimated by ≈7%, compared to -11% within LDA and 11% within GGA. The intramolecular geometries are retained, while the intermolecular distances and orientations are significantly improved relative to LDA and GGA. The quality is superior to that achieved with tailor-made empirical VDW corrections ad hoc [M. G. Del Pópolo, C. Pinilla, and P. Ballone, J. Chem. Phys. 126, 144705 (2007)]. We also analyse the performance of an optimized version of this non-empirical functional, where the screening properties of the exchange have been tuned to reproduce high-level quantum chemical calculations [J. Klimes, D. Bowler, and A. Michaelides, J. Phys.: Condens. Matter 22, 074203 (2010)]. The results for solids are even better with volumes and geometries reproduced within 2% of experimental data. We provide some insight into the issue of polymorphism of [bmim][Cl] crystals, and we present results for the geometry and energetics of [bmim][Tf] and [mmim][Cl] neutral and charged clusters, which validate the use of empirical force fields. PMID:22029322

  6. N2-broadening coefficients of methyl chloride: Measurements at room temperature and calculations at atmospheric temperatures

    NASA Astrophysics Data System (ADS)

    Barbouchi Ramchani, A.; Jacquemart, D.; Dhib, M.; Aroui, H.

    2014-11-01

    Infrared spectroscopic study on methyl chloride is the first step for its accurate detection in the atmosphere. In our previous work [Barbouchi Ramchani et al. J Quant Spectrosc Radiat Transfer 2013;120:1-15], line positions, intensities and self-broadening coefficients of both 12CH335Cl and 12CH337Cl isotopologues have been studied in the 6.9 μm spectral region. The present work is focused on measurements of N2-broadening coefficients for transitions of 12CH335Cl and 12CH337Cl around 6.9 μm. For that, high-resolution Fourier transform spectra of CH3Cl-N2 mixtures have been recorded at room temperature using a rapid scan Bruker IFS 120 HR interferometer at LADIR. The N2-broadening coefficients have been retrieved using a Voigt profile and a multispectrum fitting procedure. The average accuracy of the N2-broadening obtained in this work has been estimated to be between 5% and 10% depending on the transitions. The rotational J- and K-dependences of the N2-broadening coefficients have been clearly observed and modeled using empirical polynomial expansions. The 12CH335Cl-N2 line-widths of the ν5 band have also been computed using a semi-classical approach for the PR, RR and QR sub-branches. A global comparison with the experimental data from this work but also existing in the literature was then performed. Similar J- and K-rotational dependences have been observed while no clear evidence of any vibrational or isotopic dependence has been pointed out. Finally, performing theoretical calculations of the N2-broadening coefficients at various temperatures of atmospheric interest between 200 and 296 K allowed deducing the temperature exponent of the 12CH335Cl-N2 line-widths.

  7. Mn,Cd-metallothionein-2: a room temperature magnetic protein.

    PubMed

    Chang, Chia-Ching; Lee, Shang-Fan; Sun, Kein-Wen; Ho, Chien-Chang; Chen, Yu-Ting; Chang, Cheng-Hung; Kan, Lou-Sing

    2006-02-24

    Naturally occurring metallothionein (MT) is a metal binding protein, which binds to seven Zn2+ through 20 conserved cysteines and forms two metal binding clusters with a Zinc-Blende structure. We demonstrate that the MT, when substituting the Zn2+ ions by Mn2+ and Cd2+, exhibits magnetic hysteresis loop observable by SQUID from 10 to 330 K. The magnetic moment may have originated from the bridging effect of the sulfur atoms between the metal ions that leads to the alignment of the electron spins of the Mn2+ ions inside the clusters. The protein backbone may restrain the net spin moment of Mn2+ ions from thermal fluctuation. The modified magnetic-metallothionein is a novel approach to creating molecular magnets with operating temperatures up to 330 K. PMID:16403435

  8. Room Temperature Magnetic Barrier Layers in Magnetic Tunnel Junctions

    SciTech Connect

    Nelson-Cheeseman, B. B.; Wong, F. J.; Chopdekar, R. V.; Arenholz, E.; Suzuki, Y.

    2010-03-09

    We investigate the spin transport and interfacial magnetism of magnetic tunnel junctions with highly spin polarized LSMO and Fe3O4 electrodes and a ferrimagnetic NiFe2O4 (NFO) barrier layer. The spin dependent transport can be understood in terms of magnon-assisted spin dependent tunneling where the magnons are excited in the barrier layer itself. The NFO/Fe3O4 interface displays strong magnetic coupling, while the LSMO/NFO interface exhibits clear decoupling as determined by a combination of X-ray absorption spectroscopy and X-ray magnetic circular dichroism. This decoupling allows for distinct parallel and antiparallel electrode states in this all-magnetic trilayer. The spin transport of these devices, dominated by the NFO barrier layer magnetism, leads to a symmetric bias dependence of the junction magnetoresistance at all temperatures.

  9. Room Temperature Aging Study of Butyl O-rings

    SciTech Connect

    Mark Wilson

    2009-08-07

    During testing under the Enhanced Surveillance Campaign in 2001, preliminary data detected a previously unknown and potentially serious concern with recently procured butyl o-rings. All butyl o-rings molded from a proprietary formulation throughout the period circa 1999 through 2001 had less than a full cure. Tests showed that sealing force values for these suspect o-rings were much lower than expected and their physical properties were very sensitive to further post curing at elevated temperatures. Further testing confirmed that these o-rings were approximately 50% cured versus the typical industry standard of > 90% cured. Despite this condition, all suspect o-rings fully conformed to their QC acceptance requirements, including their individual product drawing requirements.

  10. Continuous wave room temperature external ring cavity quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Revin, D. G.; Hemingway, M.; Vaitiekus, D.; Cockburn, J. W.; Hempler, N.; Maker, G. T.; Malcolm, G. P. A.

    2015-06-01

    An external ring cavity quantum cascade laser operating at ˜5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm-1 is realized by the incorporation of a diffraction grating into the cavity.

  11. Continuous wave room temperature external ring cavity quantum cascade laser

    SciTech Connect

    Revin, D. G. Hemingway, M.; Vaitiekus, D.; Cockburn, J. W.; Hempler, N.; Maker, G. T.; Malcolm, G. P. A.

    2015-06-29

    An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm{sup −1} is realized by the incorporation of a diffraction grating into the cavity.

  12. Geopolymer - room-temperature ceramic matrix for composites

    SciTech Connect

    Davidovits, J.; Davidovics, M.

    1988-08-01

    The semiamorphous three-dimensional networks of polymeric Na, K, Li, and Mg aluminosilicates of both poly(sialate) and poly(sialate-siloxo) type, collectively known as geopolymers, harden at 20-120 C and are similar to thermoset resins, but are stable at up to 1200-1400 C without shrinkage. A wide variety of alkaline-resistant inorganic reinforcements, notably SiC fibers, have been combined with geopolymer matrices to yield nonburning, nonsmoking high-temperature composites. An SiC fiber-reinforced K-poly(sialate-siloxo) matrix, shaped and hardened at 70 C for 1.5 hr, develops flexural mean strengths of the order of 380 MPa that are retained after firing at up to 900 C. 16 references.

  13. Variation of Tensile Behaviour of Interstitial Free Steel Rolled at Cryogenic and Room Temperature

    NASA Astrophysics Data System (ADS)

    Anand, Gautam; Sinha, Arijit; Chattopadhyay, Partha Protim

    2012-10-01

    The deformation behaviour of interstitial free/ferritic steel has been investigated at cryogenic and room temperature. The study concerns the occurrence of microstructural damages during low temperature deformation conditions for such high stacking fault energy body centred cubic material and their role on the evolution of microstructure and mechanical properties.

  14. Ultrabright continuously tunable terahertz-wave generation at room temperature

    PubMed Central

    Hayashi, Shin'ichiro; Nawata, Kouji; Taira, Takunori; Shikata, Jun-ichi; Kawase, Kodo; Minamide, Hiroaki

    2014-01-01

    The hottest frequency region in terms of research currently lies in the ‘frequency gap' region between microwaves and infrared: terahertz waves. Although new methods for generating terahertz radiation have been developed, most sources cannot generate high-brightness terahertz beams. Here we demonstrate the generation of ultrabright terahertz waves (brightness ~0.2 GW/sr·cm2, brightness temperature of ~1018 K, peak power of >50 kW) using parametric wavelength conversion in a nonlinear crystal; this is brighter than many specialized sources such as far-infrared free-electron lasers (~1016 K, ~2 kW). We revealed novel parametric wavelength conversion using stimulated Raman scattering in LiNbO3 without stimulated Brillouin scattering using recently-developed microchip laser. Furthermore, nonlinear up-conversion techniques allow the intense terahertz waves to be visualized and their frequency determined. These results are very promising for extending applied research into the terahertz region, and we expect that this source will open up new research fields such as nonlinear optics in the terahertz region. PMID:24898269

  15. Ultrabright continuously tunable terahertz-wave generation at room temperature.

    PubMed

    Hayashi, Shin'ichiro; Nawata, Kouji; Taira, Takunori; Shikata, Jun-ichi; Kawase, Kodo; Minamide, Hiroaki

    2014-01-01

    The hottest frequency region in terms of research currently lies in the 'frequency gap' region between microwaves and infrared: terahertz waves. Although new methods for generating terahertz radiation have been developed, most sources cannot generate high-brightness terahertz beams. Here we demonstrate the generation of ultrabright terahertz waves (brightness ~0.2 GW/sr·cm(2), brightness temperature of ~10(18) K, peak power of >50 kW) using parametric wavelength conversion in a nonlinear crystal; this is brighter than many specialized sources such as far-infrared free-electron lasers (~10(16) K, ~2 kW). We revealed novel parametric wavelength conversion using stimulated Raman scattering in LiNbO3 without stimulated Brillouin scattering using recently-developed microchip laser. Furthermore, nonlinear up-conversion techniques allow the intense terahertz waves to be visualized and their frequency determined. These results are very promising for extending applied research into the terahertz region, and we expect that this source will open up new research fields such as nonlinear optics in the terahertz region. PMID:24898269

  16. Room temperature aluminum antimonide radiation detector and methods thereof

    DOEpatents

    Lordi, Vincenzo; Wu, Kuang Jen J.; Aberg, Daniel; Erhart, Paul; Coombs, III, Arthur W; Sturm, Benjamin W

    2015-03-03

    In one embodiment, a method for producing a high-purity single crystal of aluminum antimonide (AlSb) includes providing a growing environment with which to grow a crystal, growing a single crystal of AlSb in the growing environment which comprises hydrogen (H.sub.2) gas to reduce oxide formation and subsequent incorporation of oxygen impurities in the crystal, and adding a controlled amount of at least one impurity to the growing environment to effectively incorporate at least one dopant into the crystal. In another embodiment, a high energy radiation detector includes a single high-purity crystal of AlSb, a supporting structure for the crystal, and logic for interpreting signals obtained from the crystal which is operable as a radiation detector at a temperature of about 25.degree. C. In one embodiment, a high-purity single crystal of AlSb includes AlSb and at least one dopant selected from a group consisting of selenium (Se), tellurium (Te), and tin (Sn).

  17. Room temperature ionic liquid-mediated molecularly imprinted polymer monolith for the selective recognition of quinolones in pork samples.

    PubMed

    Sun, Xiangli; He, Jia; Cai, Guorui; Lin, Anqing; Zheng, Wenjie; Liu, Xuan; Chen, Langxing; He, Xiwen; Zhang, Yukui

    2010-12-01

    A novel molecularly imprinted polymer monolith was prepared by the room temperature ionic liquid-mediated in situ molecular imprinting technique, using norfloxacin (NOR) as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker. The optimal synthesis conditions and recognition properties of NOR-imprinted monolithic column were investigated. The results indicated that the imprinted monoliths exhibited good ability of selective recognition against the template and its structural analog. Using the fabricated material as solid-phase extraction sorbent, a sample pre-treatment procedure of molecularly imprinted solid-phase extraction coupling with HPLC was developed for determination of trace quinolone residues in animal tissues samples. The recoveries ranging from 78.16 to 93.50% for eight quinolones antibiotics such as marbofloxacin, NOR, ciprofloxacin, danofloxacin, difloxacin, oxolinic acid, flumequine and enrofloxacin were obtained. PMID:21082676

  18. Wetting behavior of imidazolium-containing, room-temperature molten salt. Technical report, 11 June 28-August 1984

    SciTech Connect

    Eberhart, J.G.

    1984-08-28

    A room-temperature, molten-salt system composed of 1-methyl-3-ethylimidazolium chloride plus aluminum chloride has been developed and extensively studied over the last few years. The most promising application of this liquid mixture is as a battery electrolyte, and for this reason a study was undertaken of the wettability of various candidate battery component materials by the molten salt. Advancing and receding contact angles were determined for the binary melt as a function of such variables as mixture composition, chlorination of the imidazolium ion, replacement of AlCl3 by LiCl, solid porosity, and solid surface cleaning procedure. Measurements were also made of the surface tension of the melt at one basic composition. Surface tension data was helpful in understanding the composition dependence of melt wetting behavior.

  19. Sensitive Room Temperature Photoluminescence-Based Sensing of H2S with Novel CuO-ZnO Nanorods.

    PubMed

    Liu, Xiao; Du, Baosheng; Sun, Ye; Yu, Miao; Yin, Yongqi; Tang, Wei; Chen, Chong; Sun, Lei; Yang, Bin; Cao, Wenwu; Ashfold, Michael N R

    2016-06-29

    Novel CuO nanoparticle-capped ZnO nanorods have been produced using a pulsed laser deposition (PLD) method. These nanorods are shown to grow by a CuO-nanoparticle-assisted vapor-solid-solid (V-S-S) mechanism. The photoluminescence (PL) accompanying ultraviolet illumination of these capped nanorod samples shows large variations upon exposure to trace quantities of H2S gas. The present data suggest that both the Cu-doped ZnO stem and the CuO capping nanoparticle contribute to optical H2S sensing with these CuO-ZnO nanorods. This study represents the first demonstration of PL-based H2S gas sensing, at room temperature, with sub-ppm sensitivity. It also opens the way to producing CuO-ZnO nanorods by a V-S-S mechanism using gas-phase methods other than PLD. PMID:27258907

  20. Short-time spectroscopic measurement of the temperature of solids

    NASA Astrophysics Data System (ADS)

    Mach, H.

    1984-02-01

    The short-time temperature rise dependent deformation caused by shocks on solids were measured with radiation pyrometric and spectroscopic methods. The methods can only be applied on solids emitting a measurable radiation and are based on spectral radiation and the temperature of the solid. The Planck-Kirchhoff radiation laws and the measuring method are presented. The measuring equipment consists of an image reproducing optical device and a photodetector with spectral or interference filters for wavelength selection.

  1. Structure and high temperature physical properties of glass seal materials in solid oxide electrolysis cell

    NASA Astrophysics Data System (ADS)

    Hao, Jie; Zan, Qingfeng; Ai, Desheng; Ma, Jingtao; Deng, Changsheng; Xu, Jingming

    2012-09-01

    Three series of BaO-CaO-SiO2-Al2O3, SrO-SiO2-Al2O3, and SrO-CaO-SiO2-Al2O3 glasses are prepared. Their basic physical properties are measured using dilatometry and differential scanning calorimetry from room temperature to the softening temperature. Their structures are characterized with infrared spectroscopy. The wetting characteristics of all glasses are examined by monitoring the change in shape of a cube specimen on crofer22 substrates from room temperature to flow temperature with a high temperature shape microscope. Five main absorption bands can be distinguished in the infrared absorption spectra of the three systems. The optimum ranges of sealing temperature of the glasses are determined. The 24SrO-16CaO-25SiO2-8Al2O3 glass is found to be the best sealant for the solid oxide electrolyzer/fuel cells under low loading without leakage. SrO improves the wetting ability of the glass by decreasing the contact angle between the glass and crofer22 substrates. The thermal properties of all the glasses fulfill the requirements for sealing solid oxide electrolysis/fuel cells. In terms of air tightness, the SrO-containing glass shows the best wetting ability among other glasses, and is the most suitable sealant for planar solid oxide electrolyzers/fuel cells.

  2. A novel NO2 gas sensor based on Hall effect operating at room temperature

    NASA Astrophysics Data System (ADS)

    Lin, J. Y.; Xie, W. M.; He, X. L.; Wang, H. C.

    2016-09-01

    Tungsten trioxide nanoparticles were obtained by a simple thermal oxidation approach. The structural and morphological properties of these nanoparticles are investigated using XRD, SEM and TEM. A WO3 thick film was deposited on the four Au electrodes to be a WO3 Hall effect sensor. The sensor was tested between magnetic field in a plastic test chamber. Room-temperature nitrogen dioxide sensing characteristics of Hall effect sensor were studied for various concentration levels of nitrogen dioxide at dry air and humidity conditions. A typical room-temperature response of 3.27 was achieved at 40 ppm of NO2 with a response and recovery times of 36 and 45 s, respectively. NO2 gas sensing mechanism of Hall effect sensor was also studied. The room-temperature operation, with the low deposition cost of the sensor, suggests suitability for developing a low-power cost-effective nitrogen dioxide sensor.

  3. Room temperature spin transport in undoped (110) GaAs/AlGaAs quantum wells

    SciTech Connect

    Yokota, Nobuhide Aoshima, Yohei; Ikeda, Kazuhiro; Kawaguchi, Hitoshi

    2014-02-17

    We are reporting on our first observation of a micrometer-order electron spin transport in a (110) GaAs/AlGaAs multiple quantum well (QW) at room temperature using a space- and time-resolved Kerr rotation technique. A 37-μm transport was observed within an electron spin lifetime of 1.2 ns at room temperature when using an in-plane electric field of 1.75 kV/cm. The spatio-temporal profiles of electron spins were well reproduced by the spin drift-diffusion equations coupled with the Poisson equation, supporting the validity of the measurement. The results suggest that (110) QWs are useful as a spin transport layer for semiconductor spintronic devices operating at room temperature.

  4. Room temperature optical and magnetic properties of polyvinylpyrrolidone capped ZnO nanoparticles

    SciTech Connect

    Chakrabarti, Mahuya; Chakrabarti, Keka R.; Sanyal, D.; Chakrabarti, A.

    2009-09-15

    Defect induced room temperature ferromagnetic properties of polyvinylpyrrolidone (PVP) capped nanocrystalline ZnO samples have been studied. Crystal phase and the lattice parameter of the synthesized nanocrystalline samples have been determined from X-ray diffraction spectra (XRD) and high-resolution transmission electron micrographs (HR-TEM). Room temperature photoluminescence (PL) spectrum for the bare ZnO sample shows a strong band at {approx} 379 nm and another band at {approx} 525 nm. The PL spectra also revealed that the number of oxygen vacancies in the uncapped sample is more than the PVP capped sample. Both sample exhibit ferromagnetic property at room temperature when annealed at 500 deg. C for 3 h, due to the formation of adequate oxygen vacancy related defects. The saturation magnetization for the annealed PVP capped sample is found to be larger compared to that for the uncapped sample.

  5. Room temperature supramolecular columnar liquid crystals formed by hydrogen bonding of isoquinoline derivatives

    NASA Astrophysics Data System (ADS)

    Hyup Lee, Jun; Lee, Seung Jun; Jho, Jae Young

    2014-07-01

    We report new self-assembled discotic liquid crystals exhibiting columnar mesophases at room temperature, which are constructed by intermolecular hydrogen bonding between the core of 1,3,5-trihydroxybenzene or 1,3,5-cyclohexanetricarboxylic acid and the peripheral molecules of isoquinoline derivatives. The mesomorphic properties of supramolecular liquid crystals were investigated by differential scanning calorimetry, polarized optical microscopy, and X-ray diffraction studies. The self-assembled liquid crystals exhibited rectangular columnar phases (Colro) with an ordered stacking structure of the mesogens in a column at room temperature, regardless of the type of the core molecule, due probably to the close-packed aromatic rings around a core molecule and the angular structure in three arms of the discotic mesogen. These room temperature columnar phases are rare examples for the discotic liquid crystals, and our findings in the present study provide a new way to prepare low melting columnar liquid crystalline materials for molecular electronics.

  6. Giant dielectric and magnetoelectric responses in insulating nanogranular films at room temperature

    PubMed Central

    Kobayashi, Nobukiyo; Masumoto, Hiroshi; Takahashi, Saburo; Maekawa, Sadamichi

    2014-01-01

    The electric and magnetic properties of matter are of great interest for materials science and their use in electronic applications. Large dielectric and magnetoelectric responses of materials at room temperature are a great advantage for electromagnetic device applications. Here we present a study of FeCo-MgF nanogranular films exhibiting giant dielectric and magnetoelectric responses at room temperature; with dielectric constant ε′=490 and magnetoelectric response Δε′/ε′0=3%. In these films, Fe-Co alloy-based nanometer-sized magnetic granules are dispersed in a Mg-fluoride-based insulator matrix. Insulating nanogranular films are a new class of multifunctional materials. The giant responses are caused by spin-dependent charge oscillation between magnetic granules via quantum-mechanical tunnelling. A possible application of such insulating nanogranular materials with giant response is in the construction of a tunable device, in which impedance components such as capacitance and inductance are tunable at room temperature. PMID:25048805

  7. Quality of Red Blood Cells Isolated from Umbilical Cord Blood Stored at Room Temperature

    PubMed Central

    Zhurova, Mariia; Akabutu, John; Acker, Jason

    2012-01-01

    Red blood cells (RBCs) from cord blood contain fetal hemoglobin that is predominant in newborns and, therefore, may be more appropriate for neonatal transfusions than currently transfused adult RBCs. Post-collection, cord blood can be stored at room temperature for several days before it is processed for stem cells isolation, with little known about how these conditions affect currently discarded RBCs. The present study examined the effect of the duration cord blood spent at room temperature and other cord blood characteristics on cord RBC quality. RBCs were tested immediately after their isolation from cord blood using a broad panel of quality assays. No significant decrease in cord RBC quality was observed during the first 65 hours of storage at room temperature. The ratio of cord blood to anticoagulant was associated with RBC quality and needs to be optimized in future. This knowledge will assist in future development of cord RBC transfusion product. PMID:24089645

  8. Magnetic switching of ferroelectric domains at room temperature in multiferroic PZTFT

    PubMed Central

    Evans, D.M.; Schilling, A.; Kumar, Ashok; Sanchez, D.; Ortega, N.; Arredondo, M.; Katiyar, R.S.; Gregg, J.M.; Scott, J.F.

    2013-01-01

    Single-phase magnetoelectric multiferroics are ferroelectric materials that display some form of magnetism. In addition, magnetic and ferroelectric order parameters are not independent of one another. Thus, the application of either an electric or magnetic field simultaneously alters both the electrical dipole configuration and the magnetic state of the material. The technological possibilities that could arise from magnetoelectric multiferroics are considerable and a range of functional devices has already been envisioned. Realising these devices, however, requires coupling effects to be significant and to occur at room temperature. Although such characteristics can be created in piezoelectric-magnetostrictive composites, to date they have only been weakly evident in single-phase multiferroics. Here in a newly discovered room temperature multiferroic, we demonstrate significant room temperature coupling by monitoring changes in ferroelectric domain patterns induced by magnetic fields. An order of magnitude estimate of the effective coupling coefficient suggests a value of ~1 × 10−7 sm−1. PMID:23443562

  9. Room-temperature spin-polarized organic light-emitting diodes with a single ferromagnetic electrode

    SciTech Connect

    Ding, Baofu Alameh, Kamal; Song, Qunliang

    2014-05-19

    In this paper, we demonstrate the concept of a room-temperature spin-polarized organic light-emitting diode (Spin-OLED) structure based on (i) the deposition of an ultra-thin p-type organic buffer layer on the surface of the ferromagnetic electrode of the Spin-OLED and (ii) the use of oxygen plasma treatment to modify the surface of that electrode. Experimental results demonstrate that the brightness of the developed Spin-OLED can be increased by 110% and that a magneto-electroluminescence of 12% can be attained for a 150 mT in-plane magnetic field, at room temperature. This is attributed to enhanced hole and room-temperature spin-polarized injection from the ferromagnetic electrode, respectively.

  10. A study of the microchemistry of nanocrystalline barium titanate with tetragonal and pseudocubic room temperature symmetries

    NASA Astrophysics Data System (ADS)

    Lacey, Robert A.

    The investigation of possible effects of undesired surface species on barium titanate, one of the most utilized ferroelectric ceramics, constitutes the focus of this work. Six commercial barium titanate powders from three manufacturers representing two different synthesis processes, with average particle sizes from 40 nm to 470 nm, were analyzed in this study. Four of the nanopowders exhibited pseudocubic room temperature symmetry. Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopic analysis of the nanopowders was conducted in ambient atmosphere at room temperature. High temperature DRIFT followed incorporating four avenues of analysis: moisture adsorption studies, deuterium oxide exchange studies, carbon dioxide adsorption studies, and high temperature analysis under dry air and UHP nitrogen atmospheres. At the highest temperature used in this study, 1173K, moisture and the accompanying incorporated protonic impurities were still present. The powders readily readsorbed moisture during rapid cooling, 170K/minute, to room temperature. The smallest powder, as received, formed spherical agglomerates up to 10 mum diameter. These sintered as separate units attaining diameters up to 60 mum during intermediate stage sintering. X-ray photoelectron spectroscopy indicated a surface contamination layer of 10 A to 18 A; 50--70% of which was barium carbonate, the balance being atmospheric adsorbed species. Samples cooled at 3K/minute after an 1173K calcine retained cubic symmetry as indicated with high temperature X-ray diffraction. However, spectral evidence was obtained indicating that upon the rapid cooling from the 1173K calcine, a reorientation to the room temperature tetragonal symmetry was observed. Further, SEM and TEM supported this finding with visual evidence of interfacial rearrangement including corroborating electron diffraction analysis. This data, therefore, substantiated the hypothesis that the cause of the room temperature pseudocubic

  11. Room temperature coherent control of defect spin qubits in silicon carbide.

    PubMed

    Koehl, William F; Buckley, Bob B; Heremans, F Joseph; Calusine, Greg; Awschalom, David D

    2011-11-01

    Electronic spins in semiconductors have been used extensively to explore the limits of external control over quantum mechanical phenomena. A long-standing goal of this research has been to identify or develop robust quantum systems that can be easily manipulated, for future use in advanced information and communication technologies. Recently, a point defect in diamond known as the nitrogen-vacancy centre has attracted a great deal of interest because it possesses an atomic-scale electronic spin state that can be used as an individually addressable, solid-state quantum bit (qubit), even at room temperature. These exceptional quantum properties have motivated efforts to identify similar defects in other semiconductors, as they may offer an expanded range of functionality not available to the diamond nitrogen-vacancy centre. Notably, several defects in silicon carbide (SiC) have been suggested as good candidates for exploration, owing to a combination of computational predictions and magnetic resonance data. Here we demonstrate that several defect spin states in the 4H polytype of SiC (4H-SiC) can be optically addressed and coherently controlled in the time domain at temperatures ranging from 20 to 300 kelvin. Using optical and microwave techniques similar to those used with diamond nitrogen-vacancy qubits, we study the spin-1 ground state of each of four inequivalent forms of the neutral carbon-silicon divacancy, as well as a pair of defect spin states of unidentified origin. These defects are optically active near telecommunication wavelengths, and are found in a host material for which there already exist industrial-scale crystal growth and advanced microfabrication techniques. In addition, they possess desirable spin coherence properties that are comparable to those of the diamond nitrogen-vacancy centre. This makes them promising candidates for various photonic, spintronic and quantum information applications that merge quantum degrees of freedom with classical

  12. Assessment of DNA encapsulation, a new room-temperature DNA storage method.

    PubMed

    Clermont, Dominique; Santoni, Sylvain; Saker, Safa; Gomard, Maite; Gardais, Eliane; Bizet, Chantal

    2014-06-01

    A new procedure for room-temperature storage of DNA was evaluated whereby DNA samples from human tissue, bacteria, and plants were stored under an anoxic and anhydrous atmosphere in small glass vials fitted in stainless-steel, laser-sealed capsules (DNAshells(®)). Samples were stored in DNAshells(®) at room temperature for various periods of time to assess any degradation and compare it to frozen control samples and those stored in GenTegra™ tubes. The study included analysis of the effect of accelerated aging by using a high temperature (76°C) at 50% relative humidity. No detectable DNA degradation was seen in samples stored in DNAshells(®) at room temperature for 18 months. Polymerase chain reaction experiments, pulsed field gel electrophoresis, and amplified fragment length polymorphism analyses also demonstrated that the protective properties of DNAshells(®) are not affected by storage under extreme conditions (76°C, 50% humidity) for 30 hours, guaranteeing 100 years without DNA sample degradation. However, after 30 hours of storage at 76°C, it was necessary to include adjustments to the process in order to avoid DNA loss. Successful protection of DNA was obtained for 1 week and even 1 month of storage at high temperature by adding trehalose, which provides a protective matrix. This study demonstrates the many advantages of using DNAshells(®) for room-temperature storage, particularly in terms of long-term stability, safety, transport, and applications for molecular biology research. PMID:24955733

  13. Assessment of DNA Encapsulation, a New Room-Temperature DNA Storage Method

    PubMed Central

    Santoni, Sylvain; Saker, Safa; Gomard, Maite; Gardais, Eliane; Bizet, Chantal

    2014-01-01

    A new procedure for room-temperature storage of DNA was evaluated whereby DNA samples from human tissue, bacteria, and plants were stored under an anoxic and anhydrous atmosphere in small glass vials fitted in stainless-steel, laser-sealed capsules (DNAshells®). Samples were stored in DNAshells® at room temperature for various periods of time to assess any degradation and compare it to frozen control samples and those stored in GenTegra™ tubes. The study included analysis of the effect of accelerated aging by using a high temperature (76°C) at 50% relative humidity. No detectable DNA degradation was seen in samples stored in DNAshells® at room temperature for 18 months. Polymerase chain reaction experiments, pulsed field gel electrophoresis, and amplified fragment length polymorphism analyses also demonstrated that the protective properties of DNAshells® are not affected by storage under extreme conditions (76°C, 50% humidity) for 30 hours, guaranteeing 100 years without DNA sample degradation. However, after 30 hours of storage at 76°C, it was necessary to include adjustments to the process in order to avoid DNA loss. Successful protection of DNA was obtained for 1 week and even 1 month of storage at high temperature by adding trehalose, which provides a protective matrix. This study demonstrates the many advantages of using DNAshells® for room-temperature storage, particularly in terms of long-term stability, safety, transport, and applications for molecular biology research. PMID:24955733

  14. Spintronics: Towards room temperature ferromagnetic devices via manganese and rare earth doped gallium nitride

    NASA Astrophysics Data System (ADS)

    Luen, Melvyn Oliver

    Spintronics is a multidisciplinary field aimed at the active manipulation of spin degrees of freedom in solid-state systems. The goal being the understanding of the interaction between the particle spin and its solid-state environment, and the making of useful devices based on the acquired knowledge. If Moore's law is to continue, then we need to find alternatives to conventional microelectronics. Where conventional electronic devices rely on manipulating charge to produce desired functions, spintronic devices would manipulate both the charge flow and electron spin within that flow. This would add an extra degree of freedom to microelectronics and usher in the era of truly nanoelectronic devices. Research aimed at a whole new generation of electronic devices is underway by introducing electron spin as a new or additional physical variable, and semiconductor devices that exploit this new freedom will operate faster and more efficiently than conventional microelectronic devices and offer new functionality that promises to revolutionize the electronics industry. Long recognized as the material of choice for next-generation solid-state lighting, gallium nitride (GaN) also has proven uses in the field of high power, high frequency field-effect transistors (FETs). But its promise as a material system for spintronic applications may be its ultimate legacy. In this dissertation, the growth of gallium-manganese-nitride (GaMnN) compound semiconductor alloy was investigated through the use of an in-house built metal-organic chemical vapor deposition (MOCVD) reactor. Building on previous investigations of ferromagnetic mechanisms in GaMnN, where ferromagnetism was shown to be carrier mediated, a above room temperature ferromagnetic GaMnN i-p-n diode structure was conceived. This device proved to be the first of its kind in the world, where ferromagnetic properties are controlled via proximity of the mediating holes, upon voltage bias of adjacent structure layers

  15. Photoexcited Individual Nanowires: Key Elements in Room Temperature Detection of Oxidizing Gases

    SciTech Connect

    Prades, J. D.; Jimenez-Diaz, R.; Manzanares, M.; Andreu, T.; Cirera, A.; Romano-Rodriguez, A.; Morante, J. R.

    2009-05-23

    Illuminating metal oxide semiconductors with ultra-violet light is a feasible alternative to activate chemical reactions at their surface and thus, using them as gas sensors without the necessity of heating them. Here, the response at room temperature of individual single-crystalline SnO{sub 2} nanowires towards NO{sub 2} is studied in detail. The results reveal that similar responses to those obtained with thermally activated sensors can be achieved by choosing the optimal illumination conditions. This finding paves the way to the development of conductometric gas sensors operated at room temperature. The power consumption in these devices is in range with conventional micromachined sensors.

  16. Room-temperature fabrication of light-emitting thin films based on amorphous oxide semiconductor

    NASA Astrophysics Data System (ADS)

    Kim, Junghwan; Miyokawa, Norihiko; Ide, Keisuke; Toda, Yoshitake; Hiramatsu, Hidenori; Hosono, Hideo; Kamiya, Toshio

    2016-01-01

    We propose a light-emitting thin film using an amorphous oxide semiconductor (AOS) because AOS has low defect density even fabricated at room temperature. Eu-doped amorphous In-Ga-Zn-O thin films fabricated at room temperature emitted intense red emission at 614 nm. It is achieved by precise control of oxygen pressure so as to suppress oxygen-deficiency/excess-related defects and free carriers. An electronic structure model is proposed, suggesting that non-radiative process is enhanced mainly by defects near the excited states. AOS would be a promising host for a thin film phosphor applicable to flexible displays as well as to light-emitting transistors.

  17. High room temperature optical polarization due to spin-valley coupling in monolayer WS2

    NASA Astrophysics Data System (ADS)

    Hanbicki, A. T.; McCreary, K. M.; Kioseoglou, G.; Currie, M.; Hellberg, C. S.; Friedman, A. L.; Jonker, B. T.

    2016-05-01

    We prepare single-layer WS2 films such that the photoluminescence is from either the neutral exciton or the negatively charged trion. While the neutral exciton emission has zero polarization at room temperature, we observe a room temperature optical polarization in excess of 40% for the trion. Using an applied gate voltage, we can modulate the electron density, and subsequently the polarization of the trion emission continuously from 20-40%. Both the polarization and the emission energy monotonically track the gate voltage with the emission energy increasing by 45 meV. We discuss the role electron capture by the exciton has on suppressing the intervalley scattering process.

  18. Experimental Verification of the Number Relation at Room and Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Lucas, L. J.; Martin, J. F.

    1983-01-01

    The accuracy of the Neuber equation for predicting notch root stress-strain behavior at room temperature and at 650 C was experimentally investigated. Strains on notched specimens were measured with a non-contacting, interferometric technique and stresses were simulated with smooth specimens. Predictions of notch root stress-strain response were made from the Neuber Equation and smooth specimen behavior. Neuber predictions gave very accurate results at room temperature. However, the predicted interaction of creep and stress relaxation differed from experimentally measured behavior at 650 C.

  19. A 2.5-2.7 THz Room Temperature Electronic Source

    NASA Technical Reports Server (NTRS)

    Maestrini, Alain; Mehdi, Imran; Lin, Robert; Siles, Jose Vicente; Lee, Choonsup; Gill, John; Chattopadhyay, Goutam; Schlecht, Erich; Bertrand, Thomas; Ward, John

    2011-01-01

    We report on a room temperature 2.5 to 2.7 THz electronic source based on frequency multipliers. The source utilizes a cascade of three frequency multipliers with W-band power amplifiers driving the first stage multiplier. Multiple-chip multipliers are utilized for the two initial stages to improve the power handling capability and a sub-micron anode is utilized for the final stage tripler. Room temperature measurements indicate that the source can put out a peak power of about 14 microwatts with more than 4 microwatts in the 2.5 to 2.7 THz range.

  20. Bi-modal Structure of Copper via Room-Temperature Partial Recrystallization After Cryogenic Dynamic Compression

    NASA Astrophysics Data System (ADS)

    Ahn, Dong-Hyun; Lee, Dong Jun; Kang, Minju; Park, Lee Ju; Lee, Sunghak; Kim, Hyoung Seop

    2016-04-01

    P ure copper was compressed at high strain rates (over ~3 × 103 s-1) under liquid nitrogen. This deformation resulted in bi-modal microstructures of ultrafine grains and abnormally grown micro grains, and in greater hardness (by ~30 Hv) than room-temperature, dynamically deformed copper. This bi-modal microstructure is attributable to partial recrystallization at room temperature, activated by high-energy states and by twins generated at high Zener-Hollomon parameter conditions. This result demonstrates a new approach for producing bi-modally structured materials.

  1. The role of hydrogen in room-temperature ferromagnetism at graphite surfaces

    SciTech Connect

    Ohldag, Hendrik

    2011-08-12

    We present a x-ray dichroism study of graphite surfaces that addresses the origin and magnitude of ferromagnetism in metal-free carbon. We find that, in addition to carbon {pi} states, also hydrogen-mediated electronic states exhibit a net spin polarization with significant magnetic remanence at room temperature. The observed magnetism is restricted to the top {approx}10 nm of the irradiated sample where the actual magnetization reaches {approx_equal} 15 emu/g at room temperature. We prove that the ferromagnetism found in metal-free untreated graphite is intrinsic and has a similar origin as the one found in proton bombarded graphite.

  2. Room temperature operational single electron transistor fabricated by focused ion beam deposition

    NASA Astrophysics Data System (ADS)

    Karre, P. Santosh Kumar; Bergstrom, Paul L.; Mallick, Govind; Karna, Shashi P.

    2007-07-01

    We present the fabrication and room temperature operation of single electron transistors using 8nm tungsten islands deposited by focused ion beam deposition technique. The tunnel junctions are fabricated using oxidation of tungsten in peracetic acid. Clear Coulomb oscillations, showing charging and discharging of the nanoislands, are seen at room temperature. The device consists of an array of tunnel junctions; the tunnel resistance of individual tunnel junction of the device is calculated to be as high as 25.13GΩ. The effective capacitance of the array of tunnel junctions was found to be 0.499aF, giving a charging energy of 160.6meV.

  3. Exploiting fast detectors to enter a new dimension in room-temperature crystallography

    SciTech Connect

    Owen, Robin L. Paterson, Neil; Axford, Danny; Aishima, Jun; Schulze-Briese, Clemens; Ren, Jingshan; Fry, Elizabeth E.; Stuart, David I.; Evans, Gwyndaf

    2014-05-01

    A departure from a linear or an exponential decay in the diffracting power of macromolecular crystals is observed and accounted for through consideration of a multi-state sequential model. A departure from a linear or an exponential intensity decay in the diffracting power of protein crystals as a function of absorbed dose is reported. The observation of a lag phase raises the possibility of collecting significantly more data from crystals held at room temperature before an intolerable intensity decay is reached. A simple model accounting for the form of the intensity decay is reintroduced and is applied for the first time to high frame-rate room-temperature data collection.

  4. Quantum confinement of zero-dimensional hybrid organic-inorganic polaritons at room temperature

    SciTech Connect

    Nguyen, H. S.; Lafosse, X.; Amo, A.; Bouchoule, S.; Bloch, J.; Abdel-Baki, K.; Lauret, J.-S.; Deleporte, E.

    2014-02-24

    We report on the quantum confinement of zero-dimensional polaritons in perovskite-based microcavity at room temperature. Photoluminescence of discrete polaritonic states is observed for polaritons localized in symmetric sphere-like defects which are spontaneously nucleated on the top dielectric Bragg mirror. The linewidth of these confined states is found much sharper (almost one order of magnitude) than that of photonic modes in the perovskite planar microcavity. Our results show the possibility to study organic-inorganic cavity polaritons in confined microstructure and suggest a fabrication method to realize integrated polaritonic devices operating at room temperature.

  5. Room temperature perovskite production from bimetallic alkoxides by ketone assisted oxo supplementation (KAOS)

    SciTech Connect

    Gaskins, B.C.; Lannutti, J.J.

    1996-08-01

    Barium titanate has been prepared at room temperature from a well-characterized crystalline barium titanium oxo alkoxide by reaction with acetone. An aldol condensation apparently supplies oxygen to condensing oxo alkoxide clusters. Transmission electron microscopy confirms that the crystallites so formed are dense and perfect with an average size of approximately 85 A. Characterization of reactants and products provides a tentative understanding of structural evolution and the intermediates of the transformation. Crystalline SrTiO{sub 3} and BaZrO{sub 3} were also formed at room temperature by this same method. {copyright} {ital 1996 Materials Research Society.}

  6. Single Event Effects on Space Radiation Hardened 64K SRAMS at Room temperature

    NASA Technical Reports Server (NTRS)

    Kim, O.; Schwartz, H.; McCarty, K.; Coss, J.; Barnes, C.

    1993-01-01

    The laser threshold linear Energy transfer for single event upsetscan be estimaed, even at room temperature, for space radiation hardened 64K SRAMs. The memories where independently developed to quality for the Qualified Manufacturer's List by IBM and Honeywell. The memory was so hard that high energy heavy ions generated by the Van de Graff could not determine the SEU threshold at room temperature. Use of pulsed Laser tests would meake it possible to forgo very expensive testing at ultra-high energy accelerators.

  7. Metal-Based Room-Temperature Operating Single Electron Devices Using Scanning Probe Oxidation

    NASA Astrophysics Data System (ADS)

    Matsumoto, Kazuhiko; Gotoh, Yoshitaka; TatsuroMaeda, TatsuroMaeda; Dagata, John; Harris, JamesS.

    1999-01-01

    Coulomb oscillation was clearly observed at room temperature in the singleelectron transistor fabricated by atomic force microscopy (AFM) nano-oxidationprocess. In order to obtain a clear Coulomb oscillation at room temperature, newand improved fabrication processes and measurement systems such as a pulse-modeAFM nano-oxidation process and a triaxial active feedback measurement system areintroduced. The Coulomb oscillation peaks appear with the period of 1.9 V at thedrain bias conditions of 0.25 V and 0.3 V. The current modulation rate ranges from20% to 30%.

  8. CeBr3 as a Room-Temperature, High-Resolution Gamma-Ray Detector

    SciTech Connect

    Paul Guss, Michael Reed, Ding Yuan, Alexis Reed, and Sanjoy Mukhopadhyay

    2009-09-01

    Cerium bromide (CeBr3) has become a material of interest in the race for high-resolution gamma-ray spectroscopy at room temperature. This investigation quantified the potential of CeBr3 as a room temperature, high-resolution gamma-ray detector. The performance of CeBr3 crystals was compared to other scintillation crystals of similar dimensions and detection environments. Comparison of self-activity of CeBr3 to cerium-doped lanthanum tribromide (LaBr3:Ce) was performed. Energy resolution and relative intrinsic efficiency were measured and are presented.

  9. Experimental evidence of Ga-vacancy induced room temperature ferromagnetic behavior in GaN films

    SciTech Connect

    Roul, Basanta; Kumar, Mahesh; Rajpalke, Mohana K.; Bhat, Thirumaleshwara N.; Krupanidhi, S. B.; Kalghatgi, A. T.; Kumar, Nitesh; Sundaresan, A.

    2011-10-17

    We have grown Ga deficient GaN epitaxial films on (0001) sapphire substrate by plasma-assisted molecular beam epitaxy and report the experimental evidence of room temperature ferromagnetic behavior. The observed yellow emission peak in room temperature photoluminescence spectra and the peak positioning at 300 cm{sup -1} in Raman spectra confirms the existence of Ga vacancies. The x-ray photoelectron spectroscopic measurements further confirmed the formation of Ga vacancies; since the N/Ga is found to be >1. The ferromagnetism is believed to originate from the polarization of the unpaired 2p electrons of N surrounding the Ga vacancy.

  10. Robust room temperature valley polarization in monolayer and bilayer WS2

    NASA Astrophysics Data System (ADS)

    Nayak, Pramoda K.; Lin, Fan-Cheng; Yeh, Chao-Hui; Huang, Jer-Shing; Chiu, Po-Wen

    2016-03-01

    We report robust room temperature valley polarization in chemical-vapor-deposition (CVD) grown monolayer and bilayer WS2via polarization-resolved photoluminescence measurements using excitation below the bandgap. We show that excitation with energy slightly below the bandgap of the multi-valleyed transition metal chalcogenides can effectively suppress the random redistribution of excited electrons and, thereby, greatly enhance the efficiency of valley polarization at room temperature. Compared to mechanically exfoliated WS2, our CVD grown WS2 films also show enhancement in the coupling of spin, layer and valley degree of freedom and, therefore, provide improved valley polarization. At room temperature, using below-bandgap excitation and CVD grown monolayer and bilayer WS2, we have reached a record-high valley polarization of 35% and 80%, respectively, exceeding the previously reported values of 10% and 65% for mechanically exfoliated WS2 layers using resonant excitation. This observation provides a new direction to enhance valley control at room temperature.We report robust room temperature valley polarization in chemical-vapor-deposition (CVD) grown monolayer and bilayer WS2via polarization-resolved photoluminescence measurements using excitation below the bandgap. We show that excitation with energy slightly below the bandgap of the multi-valleyed transition metal chalcogenides can effectively suppress the random redistribution of excited electrons and, thereby, greatly enhance the efficiency of valley polarization at room temperature. Compared to mechanically exfoliated WS2, our CVD grown WS2 films also show enhancement in the coupling of spin, layer and valley degree of freedom and, therefore, provide improved valley polarization. At room temperature, using below-bandgap excitation and CVD grown monolayer and bilayer WS2, we have reached a record-high valley polarization of 35% and 80%, respectively, exceeding the previously reported values of 10% and 65% for

  11. Room temperature ballistic transport in InSb quantum well nanodevices

    NASA Astrophysics Data System (ADS)

    Gilbertson, A. M.; Kormányos, A.; Buckle, P. D.; Fearn, M.; Ashley, T.; Lambert, C. J.; Solin, S. A.; Cohen, L. F.

    2011-12-01

    We report the room temperature observation of significant ballistic electron transport in shallow etched four-terminal mesoscopic devices fabricated on an InSb/AlInSb quantum well (QW) heterostructure with a crucial partitioned growth-buffer scheme. Ballistic electron transport is evidenced by a negative bend resistance signature which is quite clearly observed at 295 K and at current densities in excess of 106 A/cm2. This demonstrates unequivocally that by using effective growth and processing strategies, room temperature ballistic effects can be exploited in InSb/AlInSb QWs at practical device dimensions.

  12. Room-temperature single charge sensitivity in carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Peng, H. B.; Hughes, M. E.; Golovchenko, J. A.

    2006-12-01

    Electrical current fluctuation studies are reported for coaxial p-type and n-type single-wall carbon nanotube field-effect transistors (FETs). Abrupt discrete switching of the source-drain current is observed at room temperature. The authors attribute these random telegraph signals to charge fluctuating electron traps near the FET conduction channels. Evolution of the current-switching behavior associated with the occupancy of individual electron traps is demonstrated and analyzed statistically. The result strongly indicates room temperature single charge sensitivity in carbon nanotube FETs, which may offer potential applications for single molecule sensors based on suitably prepared FET devices.

  13. Lattice Changes in Shape Memory CuZnAl Alloys on Aging at Room Temperature

    NASA Astrophysics Data System (ADS)

    Çakmak, Seyfettýn; Artunç, Ekrem; Kayali, Nejdet; Adigüzel, Osman

    2001-09-01

    The aging behavior of CuZnAl martensites (Cu-21.62 wt.% Zn-5.68 wt.% Al and Cu-24.98 wt.% Zn-4.43 wt.% Al) at about 297 K was studied by analyzing diffraction line profiles obtained by X-ray diffractometry. For the alloys, the change of the lattice parameters and the tetragonality associated with the aging time at room temperature were investigated. The habit planes versus the aging time at room temperature were calculated using the De Vos-Aernoundt-Delaey model, based on the crystallographic theory of Wechsler-Lieberman-Read(WLR), and from the DO3→ 18R martensite transformation theory.

  14. Multiwalled carbon nanotubes sensor for organic liquid detection at room temperature

    NASA Astrophysics Data System (ADS)

    Chaudhary, Deepti; Khare, Neeraj; Vankar, V. D.

    2016-04-01

    We have explored the possibility of using multiwalled carbon nanotubes (MWCNTs) as room temperature chemical sensor for the detection of organic liquids such as ethanol, propanol, methanol and toluene. MWCNTs were synthesized by thermal chemical vapor deposition (TCVD) technique. The interdigitated electrodes were fabricated by conventional photolithography technique. The sensor was fabricated by drop depositing MWCNT suspension onto the interdigitated electrodes. The sensing properties of MWCNTs sensor was studied for organic liquids detection. The resistance of sensor was found to increase upon exposure to these liquids. Sensor shows good reversibility and fast response at room temperature. Charge transfer between the organic liquid and sensing element is the dominant sensing mechanism.

  15. Enhanced performance of room-temperature-grown epitaxial thin films of vanadium dioxide

    SciTech Connect

    Nag, Joyeeta; Payzant, E Andrew; More, Karren Leslie; HaglundJr., Richard F

    2011-01-01

    Stoichiometric vanadium dioxide in bulk, thin film and nanostructured forms exhibits an insulator-to-metal transition (IMT) accompanied by a structural phase transformation, induced by temperature, light, electric fields, doping or strain. We have grown epitaxial films of vanadium dioxide on c-plane (0001) of sapphire using two different procedures involving (1) room temperature growth followed by annealing and (2) direct high temperature growth. Strain at the film-substrate interface due to growth at different temperatures leads to interesting differences in morphologies and phase transition characteristics. Comparison of the morphologies and switching characteristics of the two films shows that contrary to conventional wisdom, the room-temperature grown films have smoother, more continuous morphologies and better switching performance, consistent with the behavior of epitaxially grown semiconductors.

  16. Equation Of State With Temperature Effects For Solids

    NASA Technical Reports Server (NTRS)

    Vinet, Pascal; Ferrante, John; Smith, John R.; Rose, James H.

    1989-01-01

    Behavior at high temperature predicted from only four parameters. Equations derived to express thermodynamical properties of compressed solids at high temperatures. New equations based on fundamental considerations of thermodynamics, isothermal equation of state, and assumption thermal pressure independent of volume and varies linearly with temperature near and about Debye temperature. Using only four parameters (three are those of isothermal equation of state), new equations describe thermodynamic behavior of material over range of temperatures from approximately Debye temperature to melting point.

  17. Thermal diffusivity and specific heat of dental casting alloys at room and elevated temperatures.

    PubMed

    Asaoka, K

    1997-06-01

    Thermal diffusivity and specific heat of four groups of dental casting alloys (Ag-based, Au-Pd, high karat and Ni-based alloys) were determined. Measurements were carried out from room temperature to 750 degrees C in an evacuated electric furnace with a laser flash thermal constant analyzer. There was no significant difference between the values of thermal diffusivity in the Ag-based and high karat alloys; 18-24 and 40-53 mm2/s, at room temperature and at 600 degrees C, respectively. For Au-Pd and Ni-based alloys, diffusivity was 8-12 and 3-4 mm2/s at room temperature, and 19-22 and 5-6 mm2/s at 600 degrees C, respectively. The thermal diffusivity of the alloys was significantly low compared to that of the pure-metals of which they were composed. Specific heat was determined as 0.14-0.16, 0.24-0.34, 0.17-0.19 and 0.45-0.51 kJ/(kg.K) for high karat, Ag-based, Au-Pd and Ni-based alloys, respectively, at room temperature. Oxidation of the Ni-based alloy at elevated temperature affected the value of specific heat measured. PMID:9550004

  18. Self-generated Local Heating Induced Nanojoining for Room Temperature Pressureless Flexible Electronic Packaging

    PubMed Central

    Peng, Peng; Hu, Anming; Gerlich, Adrian P.; Liu, Yangai; Zhou, Y. Norman

    2015-01-01

    Metallic bonding at an interface is determined by the application of heat and/or pressure. The means by which these are applied are the most critical for joining nanoscale structures. The present study considers the feasibility of room-temperature pressureless joining of copper wires using water-based silver nanowire paste. A novel mechanism of self-generated local heating within the silver nanowire paste and copper substrate system promotes the joining of silver-to-silver and silver-to-copper without any external energy input. The localized heat energy was delivered in-situ to the interfaces to promote atomic diffusion and metallic bond formation with the bulk component temperature stays near room-temperature. This local heating effect has been detected experimentally and confirmed by calculation. The joints formed at room-temperature without pressure achieve a tensile strength of 5.7 MPa and exhibit ultra-low resistivity in the range of 101.3 nOhm·m. The good conductivity of the joint is attributed to the removal of organic compounds in the paste and metallic bonding of silver-to-copper and silver-to-silver. The water-based silver nanowire paste filler material is successfully applied to various flexible substrates for room temperature bonding. The use of chemically generated local heating may become a potential method for energy in-situ delivery at micro/nanoscale. PMID:25788019

  19. Numerical Modelling of Airflow and Temperature Distribution in a Living Room with Different Heat Exchange Conditions

    NASA Astrophysics Data System (ADS)

    Gendelis, S.; Jakovičs, A.

    2010-01-01

    Numerical mathematical modelling of the indoor thermal conditions and of the energy losses for separate rooms is an important part of the analysis of the heat-exchange balance and energy efficiency in buildings. The measurements of heat transfer coefficients for bounding structures, the air-tightness tests and thermographic diagnostics done for a building allow the influence of those factors to be predicted more correctly in developed numerical models. The temperature distribution and airflows in a typical room (along with the heat losses) were calculated for different heater locations and solar radiation (modelled as a heat source) through the window, as well as various pressure differences between the openings in opposite walls. The airflow velocities and indoor temperature, including its gradient, were also analysed as parameters of thermal comfort conditions. The results obtained show that all of the listed factors have an important influence on the formation of thermal comfort conditions and on the heat balance in a room.

  20. A novel room temperature-induced chemical etching (RTCE) technique for the enlargement of fission tracks in Lexan polycarbonate SSNTD

    NASA Astrophysics Data System (ADS)

    Chavan, Vivek; Kalsi, P. C.; Manchanda, V. K.

    2011-02-01

    The chemical or electrochemical etching is an essential step to enlarge the ion-induced latent tracks in solid state nuclear track detectors (SSNTDs). In these methods, above ambient temperatures (˜60 °C) and moderately high concentrations of alkali are required for about 1-2 h to enlarge the latent tracks. Microwave induced chemical etching method is reported to reduce the etching time for alpha tracks from 3 to 4 h to 25 min for CR-39 detector. In the present work, a room temperature-induced chemical etching employing ethanolamine as a new etchant has been investigated for the first time to enlarge the fission tracks in Lexan polycarbonate SSNTD. The tracks developed in the Lexan detectors etched at room temperature using ethanolamine are compared with those etched with routinely used chemical etching (CE) technique in 6 N NaOH at 60 °C. The bulk etch and track etch rates are also reported. The detection efficiency of RTCE method is determined and compared with that of CE method. The RTCE technique is found to be simple, fast and convenient.

  1. Shuttle suppression in room temperature sodium-sulfur batteries using ion selective polymer membranes.

    PubMed

    Bauer, I; Kohl, M; Althues, H; Kaskel, S

    2014-03-25

    A sodiated Nafion-coating on a porous polypropylene backbone was used as a cation selective separator for room temperature sodium-sulfur batteries. The capacity of the cells after 20 cycles could be enhanced by 75% to 350 mA h g(sulfur)(-1) using the new separator. PMID:24522659

  2. Palladium-Catalyzed Chemoselective and Biocompatible Functionalization of Cysteine-Containing Molecules at Room Temperature.

    PubMed

    Al-Shuaeeb, Riyadh Ahmed Atto; Kolodych, Sergii; Koniev, Oleksandr; Delacroix, Sébastien; Erb, Stéphane; Nicolaÿ, Stéphanie; Cintrat, Jean-Christophe; Brion, Jean-Daniel; Cianférani, Sarah; Alami, Mouâd; Wagner, Alain; Messaoudi, Samir

    2016-08-01

    The third generation of aminobiphenyl palladacycle pre-catalyst "G3-Xantphos" enables functionalization of peptides containing cysteine in high yields. The conjugation (bioconjugation) occurs chemoselectively at room temperature under biocompatible conditions. Extension of the method to protein functionalization allows selective bioconjugation of the trastuzumab antibody. PMID:27362372

  3. Room-temperature operation of a Co:MgF2 laser

    NASA Technical Reports Server (NTRS)

    Welford, D.; Moulton, P. F.

    1988-01-01

    A normal-mode, pulsed Co:MgF2 laser has been operated at room temperature for the first time. Continuous tuning from 1750 to 2500 nm with pulse energies up to 70 mJ and 46-percent slope efficiency was obtained with a 1338-nm Nd:YAG pump laser.

  4. Electrical Resistivity of Natural Diamond and Diamond Films Between Room Temperature and 1200 C: Status Update

    NASA Technical Reports Server (NTRS)

    Vandersande, Jan W.; Zoltan, L. D.

    1993-01-01

    The electrical resistivity of diamond films has been measured between room temperature and 1200 C. The films were grown by either microwave Plasma CVD or combustion flame at three different places. The resistivities of the current films are compared to those measured for both natural IIa diamond and films grown only one to two years ago.

  5. Room-Temperature Gold-Catalysed Arylation of Heteroarenes: Complementarity to Palladium Catalysis.

    PubMed

    Cresswell, Alexander J; Lloyd-Jones, Guy C

    2016-08-26

    Tailoring of the pre-catalyst, the oxidant and the arylsilane enables the first room-temperature, gold-catalysed, innate C-H arylation of heteroarenes. Regioselectivity is consistently high and, in some cases, distinct from that reported with palladium catalysis. Tolerance to halides and boronic esters, in both the heteroarene and silane partners, provides orthogonality to Suzuki-Miyaura coupling. PMID:27325239

  6. Laser action from a terbium beta-ketoenolate at room temperature

    NASA Technical Reports Server (NTRS)

    Bjorklund, S.; Filipescu, N.; Hurt, C. R.; Kellermeyer, G.; Mc Avoy, N.

    1969-01-01

    Laser activity is achieved in a solution of terbium tris at room temperature in a liquid solvent of acetonitrile or p-dioxane. After precipitation, the microcrystals of hydrated tris chelate are filtered, washed in distilled water, and dried. They show no signs of deterioration after storage.

  7. Red-light-emitting laser diodes operating CW at room temperature

    NASA Technical Reports Server (NTRS)

    Kressel, H.; Hawrylo, F. Z.

    1976-01-01

    Heterojunction laser diodes of AlGaAs have been prepared with threshold current densities substantially below those previously achieved at room temperature in the 7200-8000-A spectral range. These devices operate continuously with simple oxide-isolated stripe contacts to 7400 A, which extends CW operation into the visible (red) portion of the spectrum.

  8. Deterministic switching of ferromagnetism at room temperature using an electric field

    NASA Astrophysics Data System (ADS)

    Heron, J. T.; Bosse, J. L.; He, Q.; Gao, Y.; Trassin, M.; Ye, L.; Clarkson, J. D.; Wang, C.; Liu, Jian; Salahuddin, S.; Ralph, D. C.; Schlom, D. G.; Íñiguez, J.; Huey, B. D.; Ramesh, R.

    2014-12-01

    The technological appeal of multiferroics is the ability to control magnetism with electric field. For devices to be useful, such control must be achieved at room temperature. The only single-phase multiferroic material exhibiting unambiguous magnetoelectric coupling at room temperature is BiFeO3 (refs 4 and 5). Its weak ferromagnetism arises from the canting of the antiferromagnetically aligned spins by the Dzyaloshinskii-Moriya (DM) interaction. Prior theory considered the symmetry of the thermodynamic ground state and concluded that direct 180-degree switching of the DM vector by the ferroelectric polarization was forbidden. Instead, we examined the kinetics of the switching process, something not considered previously in theoretical work. Here we show a deterministic reversal of the DM vector and canted moment using an electric field at room temperature. First-principles calculations reveal that the switching kinetics favours a two-step switching process. In each step the DM vector and polarization are coupled and 180-degree deterministic switching of magnetization hence becomes possible, in agreement with experimental observation. We exploit this switching to demonstrate energy-efficient control of a spin-valve device at room temperature. The energy per unit area required is approximately an order of magnitude less than that needed for spin-transfer torque switching. Given that the DM interaction is fundamental to single-phase multiferroics and magnetoelectrics, our results suggest ways to engineer magnetoelectric switching and tailor technologically pertinent functionality for nanometre-scale, low-energy-consumption, non-volatile magnetoelectronics.

  9. Light-induced long-range hydrogen motion in a-Si:H at room temperature

    NASA Astrophysics Data System (ADS)

    Cheong, Hyeonsik M.; Lee, S.-H.; Nelson, B. P.; Mascarenhas, A.; Deb, S. K.

    2001-03-01

    We demonstrate that one can detect minuscule amounts of hydrogen diffusion out of a-Si:H under illumination at room temperature, by monitoring the changes in the Raman spectrum of a-WO3 as a function of illumination. The Staebler-Wronski effect, the light-induce creation of metastable defects in hydrogenated amorphous silicon (a-Si:H), has been one of the major problems that has limited the performance of solar cells based on this material. The recently suggested ¡®hydrogen collision model¡¯ can explain many aspects of the Staebler-Wronski effect, but assumes that the photogenerated mobile hydrogen atoms can move a long distance at room temperature. However, light-induced hydrogen motion in a-Si:H has not been experimentally observed at room temperature. We utilized the high sensitivity of the Raman spectrum of electrochromic a-WO3 to hydrogen insertion to probe the long-range motion of hydrogen at room temperature. We deposited a thin (200 nm) layer of a-WO3 on top of a-Si:H, and under illumination, a change in the Raman spectrum was detected. By comparing the Raman signal changes with those for control experiments where hydrogen is electrochemically inserted into a-WO_3, we can estimate semiquantitatively the amount of hydrogen that diffuses out of the a-Si:H layer.

  10. GREEN SYNTHESIS OF SILVER AND PALLADIUM NANOPARTICLES AT ROOM TEMPERATURE USING COFFEE AND TEA EXTRACT

    EPA Science Inventory

    An extremely simple green approach that generates bulk quantities of nanocrystals of noble metals such as silver (Ag) and palladium (Pd) using coffee and tea extract at room temperature is described. The single-pot method uses no surfactant, capping agent, and/or template. The ob...

  11. Deterministic switching of ferromagnetism at room temperature using an electric field.

    PubMed

    Heron, J T; Bosse, J L; He, Q; Gao, Y; Trassin, M; Ye, L; Clarkson, J D; Wang, C; Liu, Jian; Salahuddin, S; Ralph, D C; Schlom, D G; Iñiguez, J; Huey, B D; Ramesh, R

    2014-12-18

    The technological appeal of multiferroics is the ability to control magnetism with electric field. For devices to be useful, such control must be achieved at room temperature. The only single-phase multiferroic material exhibiting unambiguous magnetoelectric coupling at room temperature is BiFeO3 (refs 4 and 5). Its weak ferromagnetism arises from the canting of the antiferromagnetically aligned spins by the Dzyaloshinskii-Moriya (DM) interaction. Prior theory considered the symmetry of the thermodynamic ground state and concluded that direct 180-degree switching of the DM vector by the ferroelectric polarization was forbidden. Instead, we examined the kinetics of the switching process, something not considered previously in theoretical work. Here we show a deterministic reversal of the DM vector and canted moment using an electric field at room temperature. First-principles calculations reveal that the switching kinetics favours a two-step switching process. In each step the DM vector and polarization are coupled and 180-degree deterministic switching of magnetization hence becomes possible, in agreement with experimental observation. We exploit this switching to demonstrate energy-efficient control of a spin-valve device at room temperature. The energy per unit area required is approximately an order of magnitude less than that needed for spin-transfer torque switching. Given that the DM interaction is fundamental to single-phase multiferroics and magnetoelectrics, our results suggest ways to engineer magnetoelectric switching and tailor technologically pertinent functionality for nanometre-scale, low-energy-consumption, non-volatile magnetoelectronics. PMID:25519134

  12. Room temperature ferromagnetism in ZnO using non-magnetic dopants

    NASA Astrophysics Data System (ADS)

    Ali, Nasir; Atri, Asha; Singh, Budhi; Ghosh, Subhasis

    2016-05-01

    We studied the magnetic properties of Ag and Cu doped ZnO thin films deposited by magnetron sputtering. Robust room temperature ferromagnetism is observed in the films. Comparative to Cu doped films Ag doped films shows significant increase in ferromagnetism. Spectroscopic ellipsometry studies are also done to see the change in band structure with different metal doping content.

  13. Adhesive for polyester films cures at room temperature, has high initial tack

    NASA Technical Reports Server (NTRS)

    Christian, C. M.; Fust, G. W.; Welchel, C. J.

    1966-01-01

    Quick room-temperature-cure adhesive bonds polyester-insulated flat electrical cables to metal surfaces and various other substrates. The bond strength of the adhesive may be considerably increased by first applying a commercially available polyamide primer to the polyester film.

  14. Extreme Sensitivity of Room-Temperature Photoelectric Effect for Terahertz Detection.

    PubMed

    Huang, Zhiming; Zhou, Wei; Tong, Jinchao; Huang, Jingguo; Ouyang, Cheng; Qu, Yue; Wu, Jing; Gao, Yanqing; Chu, Junhao

    2016-01-01

    Extreme sensitivity of room-temperature photoelectric effect for terahertz (THz) detection is demonstrated by generating extra carriers in an electromagnetic induced well located at the semiconductor, using a wrapped metal-semiconductor-metal configuration. The excellent performance achieved with THz detectors shows great potential to open avenues for THz detection. PMID:26542882

  15. Aqueous synthesis of porous platinum nanotubes at room temperature and their intrinsic peroxidase-like activity.

    PubMed

    Cai, Kai; Lv, Zhicheng; Chen, Kun; Huang, Liang; Wang, Jing; Shao, Feng; Wang, Yanjun; Han, Heyou

    2013-07-11

    Platinum nanotubes (PtNTs) exhibiting high porosity were constructed by sacrificing the exterior of tellurium nanowires (TeNWs) and disintegrating the inner part spontaneously in aqueous solution at room temperature, in which the Kirkendall effect may play an important role. The present PtNTs exhibited intrinsic peroxidase-like activity in the presence of H2O2. PMID:23598712

  16. Crystal induced phosphorescence from Benz(a)anthracene microcrystals at room temperature.

    PubMed

    Maity, Samir; Mazumdar, Prativa; Shyamal, Milan; Sahoo, Gobinda Prasad; Misra, Ajay

    2016-03-15

    Pure organic compounds that are also phosphorescent at room temperature are very rare in literature. Here, we report efficient phosphorescence emission from aggregated hydrosol of Benz(a)anthracene (BaA) at room temperature. Aggregated hydrosol of BaA has been synthesized by re-precipitation method and SDS is used as morphology directing agent. Morphology of the particles is characterized using optical and scanning electronic microcopy (SEM). Photophysical properties of the aggregated hydrosol are carried out using UV-vis, steady state and time resolved fluorescence study. The large stoke shifted structured emission from aggregated hydrosol of BaA has been explained due to phosphorescence emission of BaA at room temperature. In the crystalline state, the restricted intermolecular motions (RIM) such as rotations and vibrations are activated by crystal lattice. This rigidification effect makes the chromophore phosphorescent at room temperature. The possible stacking arrangement of the neighboring BaA within the aggregates has been substantiated by computing second order Fukui parameter as local reactivity descriptors. Computational study also reveals that the neighboring BaA molecules are present in parallel slipped conformation in its aggregated crystalline form. PMID:26720419

  17. A Knoevenagel Initiated Annulation Reaction Using Room Temperature or Microwave Conditions

    ERIC Educational Resources Information Center

    Cook, A. Gilbert

    2007-01-01

    An experiment is presented that has the student execute a Knoevenagel initiated annulation reaction. The reaction can be carried out either through use of a microwave reactor or by allowing the mixture to stand at room temperature for two days. The student is then challenged to identify the reaction product through a guided prelab exercise of the…

  18. Homogeneous linewidths of Rhodamine 6G at room temperature from cavity-enhanced spontaneous emission rates

    SciTech Connect

    Barnes, M.D.; Whitten, W.B.; Arnold, S.; Ramsey, J.M. )

    1992-11-15

    Fluorescence lifetimes of Rhodamine 6G in levitated micron-sized droplets have been measured using a time-correlated photon counting technique. The coupling of emission into spherical cavity modes of the droplet results in significant emission rate enhancements which allow estimation of the homogeneous linewidth at room temperature.

  19. Robust room temperature valley polarization in monolayer and bilayer WS2.

    PubMed

    Nayak, Pramoda K; Lin, Fan-Cheng; Yeh, Chao-Hui; Huang, Jer-Shing; Chiu, Po-Wen

    2016-03-21

    We report robust room temperature valley polarization in chemical-vapor-deposition (CVD) grown monolayer and bilayer WS2via polarization-resolved photoluminescence measurements using excitation below the bandgap. We show that excitation with energy slightly below the bandgap of the multi-valleyed transition metal chalcogenides can effectively suppress the random redistribution of excited electrons and, thereby, greatly enhance the efficiency of valley polarization at room temperature. Compared to mechanically exfoliated WS2, our CVD grown WS2 films also show enhancement in the coupling of spin, layer and valley degree of freedom and, therefore, provide improved valley polarization. At room temperature, using below-bandgap excitation and CVD grown monolayer and bilayer WS2, we have reached a record-high valley polarization of 35% and 80%, respectively, exceeding the previously reported values of 10% and 65% for mechanically exfoliated WS2 layers using resonant excitation. This observation provides a new direction to enhance valley control at room temperature. PMID:26927489

  20. 40 CFR Table B-4 to Subpart B of... - Line Voltage and Room Temperature Test Conditions

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Conditions B Table B-4 to Subpart B of Part 53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Testing Performance Characteristics of Automated Methods for SO2, CO, O3, and NO2 Pt. 53, Subpt. B, Table B-4 Table B-4 to Subpart B of Part 53—Line Voltage and Room Temperature Test Conditions Test...

  1. 40 CFR Table B-4 to Subpart B of... - Line Voltage and Room Temperature Test Conditions

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Conditions B Table B-4 to Subpart B of Part 53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Testing Performance Characteristics of Automated Methods for SO2, CO, O3, and NO2 Pt. 53, Subpt. B, Table B-4 Table B-4 to Subpart B of Part 53—Line Voltage and Room Temperature Test Conditions Test...

  2. 40 CFR Table B-4 to Subpart B of... - Line Voltage and Room Temperature Test Conditions

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Conditions B Table B-4 to Subpart B of Part 53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Testing Performance Characteristics of Automated Methods for SO2, CO, O3, and NO2 Pt. 53, Subpt. B, Table B-4 Table B-4 to Subpart B of Part 53—Line Voltage and Room Temperature Test Conditions Test...

  3. Crystal induced phosphorescence from Benz(a)anthracene microcrystals at room temperature

    NASA Astrophysics Data System (ADS)

    Maity, Samir; Mazumdar, Prativa; Shyamal, Milan; Sahoo, Gobinda Prasad; Misra, Ajay

    2016-03-01

    Pure organic compounds that are also phosphorescent at room temperature are very rare in literature. Here, we report efficient phosphorescence emission from aggregated hydrosol of Benz(a)anthracene (BaA) at room temperature. Aggregated hydrosol of BaA has been synthesized by re-precipitation method and SDS is used as morphology directing agent. Morphology of the particles is characterized using optical and scanning electronic microcopy (SEM). Photophysical properties of the aggregated hydrosol are carried out using UV-vis, steady state and time resolved fluorescence study. The large stoke shifted structured emission from aggregated hydrosol of BaA has been explained due to phosphorescence emission of BaA at room temperature. In the crystalline state, the restricted intermolecular motions (RIM) such as rotations and vibrations are activated by crystal lattice. This rigidification effect makes the chromophore phosphorescent at room temperature. The possible stacking arrangement of the neighboring BaA within the aggregates has been substantiated by computing second order Fukui parameter as local reactivity descriptors. Computational study also reveals that the neighboring BaA molecules are present in parallel slipped conformation in its aggregated crystalline form.

  4. RANEY® Ni catalyzed transfer hydrogenation of levulinate esters to γ-valerolactone at room temperature.

    PubMed

    Yang, Zhen; Huang, Yao-Bing; Guo, Qing-Xiang; Fu, Yao

    2013-06-11

    A catalytic transfer hydrogenation process was developed for the production of γ-valerolactone (GVL) from ethyl levulinate (EL) and a H-donor at room temperature. Ethyl levulinate was almost quantitatively converted to γ-valerolactone. Further, a two step process for producing GVL from biomass derived platform molecules was also reported. PMID:23648801

  5. Structure determination of an integral membrane protein at room temperature from crystals in situ

    SciTech Connect

    Axford, Danny; Foadi, James; Hu, Nien-Jen; Choudhury, Hassanul Ghani; Iwata, So; Beis, Konstantinos; Evans, Gwyndaf; Alguel, Yilmaz

    2015-05-14

    The X-ray structure determination of an integral membrane protein using synchrotron diffraction data measured in situ at room temperature is demonstrated. The structure determination of an integral membrane protein using synchrotron X-ray diffraction data collected at room temperature directly in vapour-diffusion crystallization plates (in situ) is demonstrated. Exposing the crystals in situ eliminates manual sample handling and, since it is performed at room temperature, removes the complication of cryoprotection and potential structural anomalies induced by sample cryocooling. Essential to the method is the ability to limit radiation damage by recording a small amount of data per sample from many samples and subsequently assembling the resulting data sets using specialized software. The validity of this procedure is established by the structure determination of Haemophilus influenza TehA at 2.3 Å resolution. The method presented offers an effective protocol for the fast and efficient determination of membrane-protein structures at room temperature using third-generation synchrotron beamlines.

  6. A gadolinium(iii) complex that shows room-temperature phosphorescence in the crystalline state.

    PubMed

    Nakai, Hidetaka; Kitagawa, Kazuhiro; Seo, Juncheol; Matsumoto, Takahiro; Ogo, Seiji

    2016-07-19

    This paper presents a gadolinium(iii) complex that shows blue phosphorescence in the crystalline state at room temperature under air atmosphere; color of the crystals can be changed to pale-green from blue by doping of 1-naphthol. PMID:27221814

  7. Room-temperature phosphorescence logic gates developed from nucleic acid functionalized carbon dots and graphene oxide.

    PubMed

    Gui, Rijun; Jin, Hui; Wang, Zonghua; Zhang, Feifei; Xia, Jianfei; Yang, Min; Bi, Sai; Xia, Yanzhi

    2015-05-14

    Room-temperature phosphorescence (RTP) logic gates were developed using capture ssDNA (cDNA) modified carbon dots and graphene oxide (GO). The experimental results suggested the feasibility of these developed RTP-based "OR", "INHIBIT" and "OR-INHIBIT" logic gate operations, using Hg(2+), target ssDNA (tDNA) and doxorubicin (DOX) as inputs. PMID:25882250

  8. High performance nickel-palladium nanocatalyst for hydrogen generation from alkaline hydrous hydrazine at room temperature

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Debaleena; Mandal, Kaustab; Dasgupta, Subrata

    2015-08-01

    Room temperature synthesized highly active bimetallic Ni60Pd40 nanocatalyst with large surface area (150 m2g-1) exerts 100% selectivity towards hydrogen generation (3 equivalents of gas in 60 min) from hydrous hydrazine under alkaline and ambient reaction conditions. This low noble metal content catalyst offers a new prospect for on-board hydrogen production system.

  9. Aerobic Oxidation in Nanomicelles of Aryl Alkynes, in Water at Room Temperature**

    PubMed Central

    Handa, Sachin; Fennewald, James C.; Rainey, Shane

    2014-01-01

    On the basis of the far higher solubility of oxygen gas inside the hydrocarbon core of nanomicelles, metal and peroxide free aerobic oxidation of aryl alkynes has been achieved in water at room temperature. Many examples are offered that illustrate broad functional group tolerance. The overall process is environmentally friendly, documented by the associated low E Factors. PMID:24616243

  10. Instantaneous radioiodination of rose bengal at room temperature and a cold-kit therefor. [DOE patent application

    DOEpatents

    O'Brien, H. Jr.; Hupf, H.B.; Wanek, P.M.

    The disclosure relates to the radioiodination of rose bengal at room temperature and a cold-kit therefor. A purified rose bengal tablet is stirred into acidified ethanol at or near room temperature, until a suspension forms. Reductant-free /sup 125/I/sup -/ is added and the resulting mixture stands until the exchange label reaction occurs at room temperature. A solution of sterile isotonic phosphate buffer and sodium hydroxide is added and the final resulting mixture is sterilized by filtration.

  11. Room-temperature magnetism on the zigzag edges of phosphorene nanoribbons

    NASA Astrophysics Data System (ADS)

    Yang, Guang; Xu, Shenglong; Zhang, Wei; Ma, Tianxing; Wu, Congjun

    2016-08-01

    Searching for room-temperature ferromagnetic semiconductors has evolved into a broad field of material science and spintronics for decades, nevertheless, these novel states remain rare. Phosphorene, a monolayer black phosphorus with a puckered honeycomb lattice structure possessing a finite band gap and high carrier mobility, has been synthesized recently. Here we show, by means of two different large-scale quantum Monte Carlo methods, that relatively weak interactions can lead to remarkable edge magnetism in the phosphorene nanoribbons. The ground state constrained path quantum Monte Carlo simulations reveal strong ferromagnetic correlations along the zigzag edges, and the finite temperature determinant quantum Monte Carlo calculations show a high Curie temperature up to room temperature.

  12. Mechanical properties and constitutive behaviors of as-cast 7050 aluminum alloy from room temperature to above the solidus temperature

    NASA Astrophysics Data System (ADS)

    Bai, Qing-ling; Li, Hong-xiang; Du, Qiang; Zhang, Ji-shan; Zhuang, Lin-zhong

    2016-08-01

    The mechanical properties and constitutive behaviors of as-cast AA7050 in both the solid and semi-solid states were determined using the on-cooling and in situ solidification approaches, respectively. The results show that the strength in the solid state tends to increase with decreasing temperature. The strain rate plays an important role in the stress-strain behaviors at higher temperatures, whereas the influence becomes less pronounced and irregular when the temperature is less than 250°C. The experimental data were fitted to the extended Ludwik equation, which is suitable to describe the mechanical behavior of the materials in the as-cast state. In the semi-solid state, both the strength and ductility of the alloy are high near the solidus temperature and decrease drastically with decreasing solid fraction. As the solid fraction is less than 0.97, the maximum strength only slightly decreases, whereas the post-peak ductility begins to increase. The experimental data were fitted to the modified creep law, which is used to describe the mechanical behavior of semi-solid materials, to determine the equivalent parameter f GBWL, i.e., the fraction of grain boundaries covered by liquid phase.

  13. Direct measurement of osmotic pressure of glycosaminoglycan solutions by membrane osmometry at room temperature.

    PubMed

    Chahine, Nadeen O; Chen, Faye H; Hung, Clark T; Ateshian, Gerard A

    2005-09-01

    Articular cartilage is a hydrated soft tissue composed of negatively charged proteoglycans fixed within a collagen matrix. This charge gradient causes the tissue to imbibe water and swell, creating a net osmotic pressure that enhances the tissue's ability to bear load. In this study we designed and utilized an apparatus for directly measuring the osmotic pressure of chondroitin sulfate, the primary glycosaminoglycan found in articular cartilage, in solution with varying bathing ionic strength (0.015 M, 0.15 M, 0.5 M, 1 M, and 2 M NaCl) at room temperature. The osmotic pressure (pi) was found to increase nonlinearly with increasing chondroitin sulfate concentration and decreasing NaCl ionic bath environment. Above 1 M NaCl, pi changes negligibly with further increases in salt concentration, suggesting that Donnan osmotic pressure is negligible above this threshold, and the resulting pressure is attributed to configurational entropy. Results of the current study were also used to estimate the contribution of osmotic pressure to the stiffness of cartilage based on theoretical and experimental considerations. Our findings indicate that the osmotic pressure resulting from configurational entropy is much smaller in cartilage (based on an earlier study on bovine articular cartilage) than in free solution. The rate of change of osmotic pressure with compressive strain is found to contribute approximately one-third of the compressive modulus (H(A)(eff)) of cartilage (Pi approximately H(A)(eff)/3), with the balance contributed by the intrinsic structural modulus of the solid matrix (i.e., H(A) approximately 2H(A)(eff)/3). A strong dependence of this intrinsic modulus on salt concentration was found; therefore, it appears that proteoglycans contribute structurally to the magnitude of H(A), in a manner independent of osmotic pressure. PMID:15980166

  14. Room temperature phosphorimetric determination of bromate in flour based on energy transfer.

    PubMed

    Menendez-Miranda, Mario; Fernandez-Argüelles, Maria T; Costa-Fernandez, Jose M; Pereiro, Rosario; Sanz-Medel, Alfredo

    2013-11-15

    Determination of bromate ions in contaminated flour samples by using a room temperature phosphorescence (RTP) optosensor is described. The optosensor is based on the non-radiative energy transfer from α-bromonaphthalene (a phosphorescent molecule insensitive to the presence of the analyte) acting as donor, to an energy acceptor bromate-sensitive molecule (trifluoperazine hydrochloride). The RTP emission of the selected donor greatly overlaps with the absorption spectrum of the acceptor, resulting in a decrease of the measured signal as the concentration of bromate ions increases. A simple and general procedure is proposed to carry out the incorporation of both the donor and acceptor molecules in an appropriate solid material (sensing phase) through the co-immobilization of the species in a sol-gel inorganic matrix. The optimum amounts of the sol-gel precursors, including silica precursors, type of catalysis, and concentrations of donor and acceptor molecules, have been evaluated in order to obtain the best analytical features of the proposed optosensor for bromate determination. The highly stable developed sensing phase shows a selective and reversible response towards bromate even in presence of dissolved oxygen (a well-known quencher of the RTP). The calibration graphs were linear up to 200 mg L(-1), with a detection limit for bromate dissolved in aqueous medium of 0.2 mg L(-1). Sample throughput of the proposed optosensor was about 18 measurements h(-1). Application of the developed sensing phase was successfully proved for the detection of bromate ions in commercial flours, obtaining good recoveries. PMID:24148398

  15. Room Temperature Oxide Deposition Approach to Fully Transparent, All-Oxide Thin-Film Transistors.

    PubMed

    Rembert, Thomas; Battaglia, Corsin; Anders, André; Javey, Ali

    2015-10-28

    A room temperature cathodic arc deposition technique is used to produce high-mobility ZnO thin films for low voltage thin-film transistors (TFTs) and digital logic inverters. All-oxide, fully transparent devices are fabricated on alkali-free glass and flexible polyimide foil, exhibiting high performance. This provides a practical materials platform for the low-temperature fabrication of all-oxide TFTs on virtually any substrate. PMID:26455916

  16. Room temperature broadband terahertz gains in graphene heterostructures based on inter-layer radiative transitions

    SciTech Connect

    Tang, Linlong; Du, Jinglei; Shi, Haofei Wei, Dongshan; Du, Chunlei

    2014-10-15

    We exploit inter-layer radiative transitions to provide gains to amplify terahertz waves in graphene heterostructures. This is achieved by properly doping graphene sheets and aligning their energy bands so that the processes of stimulated emissions can overwhelm absorptions. We derive an expression for the gain estimation and show the gain is insensitive to temperature variation. Moreover, the gain is broadband and can be strong enough to compensate the free carrier loss, indicating graphene based room temperature terahertz lasers are feasible.

  17. Experimental data of the static behavior of reinforced concrete beams at room and low temperature

    PubMed Central

    Mirzazadeh, M. Mehdi; Noël, Martin; Green, Mark F.

    2016-01-01

    This article provides data on the static behavior of reinforced concrete at room and low temperature including, strength, ductility, and crack widths of the reinforced concrete. The experimental data on the application of digital image correlation (DIC) or particle image velocimetry (PIV) in measuring crack widths and the accuracy and precision of DIC/PIV method with temperature variations when is used for measuring strains is provided as well. PMID:27158650

  18. Experimental data of the static behavior of reinforced concrete beams at room and low temperature.

    PubMed

    Mirzazadeh, M Mehdi; Noël, Martin; Green, Mark F

    2016-06-01

    This article provides data on the static behavior of reinforced concrete at room and low temperature including, strength, ductility, and crack widths of the reinforced concrete. The experimental data on the application of digital image correlation (DIC) or particle image velocimetry (PIV) in measuring crack widths and the accuracy and precision of DIC/PIV method with temperature variations when is used for measuring strains is provided as well. PMID:27158650

  19. All-solid-state lithium-oxygen battery with high safety in wide ambient temperature range

    NASA Astrophysics Data System (ADS)

    Kitaura, Hirokazu; Zhou, Haoshen

    2015-08-01

    There is need to develop high energy storage devices with high safety to satisfy the growing industrial demands. Here, we show the potential to realize such batteries by assembling a lithium-oxygen cell using an inorganic solid electrolyte without any flammable liquid or polymer materials. The lithium-oxygen battery using Li1.575Al0.5Ge1.5(PO4)3 solid electrolyte was examined in the pure oxygen atmosphere from room temperature to 120 °C. The cell works at room temperature and first full discharge capacity of 1420 mAh g-1 at 10 mA g-1 (based on the mass of carbon material in the air electrode) was obtained. The charge curve started from 3.0 V, and that the majority of it lay below 4.2 V. The cell also safely works at high temperature over 80 °C with the improved battery performance. Furthermore, fundamental data of the electrochemical performance, such as cyclic voltammogram, cycle performance and rate performance was obtained and this work demonstrated the potential of the all-solid-state lithium-oxygen battery for wide temperature application as a first step.

  20. All-solid-state lithium-oxygen battery with high safety in wide ambient temperature range.

    PubMed

    Kitaura, Hirokazu; Zhou, Haoshen

    2015-01-01

    There is need to develop high energy storage devices with high safety to satisfy the growing industrial demands. Here, we show the potential to realize such batteries by assembling a lithium-oxygen cell using an inorganic solid electrolyte without any flammable liquid or polymer materials. The lithium-oxygen battery using Li1.575Al0.5Ge1.5(PO4)3 solid electrolyte was examined in the pure oxygen atmosphere from room temperature to 120 °C. The cell works at room temperature and first full discharge capacity of 1420 mAh g(-1) at 10 mA g(-1) (based on the mass of carbon material in the air electrode) was obtained. The charge curve started from 3.0 V, and that the majority of it lay below 4.2 V. The cell also safely works at high temperature over 80 °C with the improved battery performance. Furthermore, fundamental data of the electrochemical performance, such as cyclic voltammogram, cycle performance and rate performance was obtained and this work demonstrated the potential of the all-solid-state lithium-oxygen battery for wide temperature application as a first step. PMID:26293134