Do thermal donors reduce the lifetimes of Czochralski-grown silicon crystals?

NASA Astrophysics Data System (ADS)

Miyamura, Y.; Harada, H.; Nakano, S.; Nishizawa, S.; Kakimoto, K.

2018-05-01

High-performance electronics require long carrier lifetimes within their silicon crystals. This paper reports the effects of thermal donors on the lifetimes of carriers in as-grown n-type silicon crystals grown by the Czochralski method. We grew silicon crystals with two different concentrations of thermal donors using the following two cooling processes: one was cooled with a 4-h halt after detaching the crystal from the melt, and the other was cooled continuously. The crystal grown with the cooling halt contained higher concentrations of thermal donors of the order of 1 × 1013 cm-3, while the crystal without the halt had no thermal donors. The measured bulk lifetimes were in the range of 15-18 ms. We concluded that thermal donors in Czochralski-grown silicon crystals do not act to reduce their lifetimes.

Ultra-fast scintillation properties of β-Ga2O3 single crystals grown by Floating Zone method

NASA Astrophysics Data System (ADS)

He, Nuotian; Tang, Huili; Liu, Bo; Zhu, Zhichao; Li, Qiu; Guo, Chao; Gu, Mu; Xu, Jun; Liu, Jinliang; Xu, Mengxuan; Chen, Liang; Ouyang, Xiaoping

2018-04-01

In this investigation, β-Ga2O3 single crystals were grown by the Floating Zone method. At room temperature, the X-ray excited emission spectrum includes ultraviolet and blue emission bands. The scintillation light output is comparable to the commercial BGO scintillator. The scintillation decay times are composed of the dominant ultra-fast component of 0.368 ns and a small amount of slightly slow components of 8.2 and 182 ns. Such fast component is superior to most commercial inorganic scintillators. In contrast to most semiconductor crystals prepared by solution method such as ZnO, β-Ga2O3 single crystals can be grown by traditional melt-growth method. Thus we can easily obtain large bulk crystals and mass production.

Material and detector properties of cadmium manganese telluride (Cd 1-xMn xTe) crystals grown by the modified floating-zone method

DOE PAGES

Hossain, A.; Gu, G. D.; Bolotnikov, A. E.; ...

2014-12-24

We demonstrated the material- and radiation-detection properties of cadmium manganese telluride (Cd 1-xMn xTe; x=0.06), a wide-band-gap semiconductor crystal grown by the modified floating-zone method. We investigated the presence of various bulk defects, such as Te inclusions, twins, and dislocations of several as-grown indium-doped Cd 1-xMn xTe crystals using different techniques, viz., IR transmission microscopy, and chemical etching. We then fabricated four planar detectors from selected CdMnTe crystals, characterized their electrical properties, and tested their performance as room-temperature X- and gamma-ray detectors. Thus, our experimental results show that CMT crystals grown by the modified floating zone method apparently are freemore » from Te inclusions. However, we still need to optimize our growth parameters to attain high-resistivity, large-volume single-crystal CdMnTe.« less

Growth, structural, optical, thermal and mechanical properties of ammonium pentaborate single crystal.

PubMed

Balakrishnan, T; Bhagavannarayana, G; Ramamurthi, K

2008-11-15

Nonlinear optical single crystals of ammonium pentaborate (APB) were grown by the slow cooling method from aqueous solution. Grown crystal was characterized by powder X-ray diffraction (PXRD) and FT-IR spectral analysis. Perfection of the grown crystal was evaluated by high-resolution X-ray diffractometry (HRXRD). The effect of nylon threading on the perfection of the grown bigger crystal was also studied by HRXRD. The range and percentage of optical transmission was ascertained by recording UV-vis-NIR spectrum. Thermal properties were investigated by TG-DTA and DSC analyses. Its mechanical hardness was estimated by Vickers microhardness tester.

Influence of solvents on the habit modification of alpha lactose monohydrate single crystals

NASA Astrophysics Data System (ADS)

Parimaladevi, P.; Srinivasan, K.

2013-02-01

Restricted evaporation of solvent method was adopted for the growth of alpha lactose monohydrate single crystals from different solvents. The crystal habits of grown crystals were analysed. The form of crystallization was confirmed by powder x-ray diffraction analysis. Thermal behaviour of the grown crystals was studied by using differential scanning calorimetry.

Fabrication of optical element from unidirectional grown imidazole-imidazolium picrate monohydrate (IIP) organic crystals for nonlinear optical applications

NASA Astrophysics Data System (ADS)

Vivek, P.; Murugakoothan, P.

2014-12-01

Nonlinear optical bulk single crystal of Imidazole-imidazolium picrate monohydrate (IIP) has been grown by Sankaranarayanan-Ramasamy (SR) method using acetonitrile as solvent. First time we report the bulk growth of IIP crystal by SR method. The transparent IIP single crystal of maximum diameter 21 mm and length 46 mm was obtained by employing SR method. The grown crystal was subjected to high resolution X-ray diffraction, UV-vis-NIR transmittance, refractive index, hardness, dielectric and laser damage threshold studies. The crystalline perfection of the grown crystal was analyzed using HRXRD. Cut off wavelength and optical transmission window of the crystal was assessed by UV-vis-NIR and the refractive index of the crystal was found. The mechanical property of the crystal was estimated by Vicker's hardness test. The dielectric property of the crystal was measured as a function of frequency. The laser damage threshold value was determined. The particle size dependent second harmonic generation efficiency for IIP was evaluated with standard reference material potassium dihydrogen phosphate (KDP) by Kurtz-Perry powder method using Nd:YAG laser, which established the existence of phase matching. The second harmonic generation (SHG) of IIP crystal was investigated by the SHG Maker fringes technique. The mechanism of growth is revealed by carrying out chemical etching using acetonitrile as etchant.

Growth of single crystalline delafossite LaCuO2 by the travelling-solvent floating zone method

NASA Astrophysics Data System (ADS)

Mohan, A.; Büchner, B.; Wurmehl, S.; Hess, C.

2014-09-01

Single crystals of LaCuO2 have been grown for the first time using the travelling-solvent floating zone method. The crystal was grown in an Ar-atmosphere by reduction of La2Cu2O5, which was used as the feed rod composition for the growth. The grown crystal has been characterized with regard to phase purity and single crystallinity using powder X-ray diffraction, energy dispersive X-ray analysis, Laue diffraction and scanning electron microscopy.

Method for the preparation of photochromic insulating crystals

DOEpatents

Abraham, M.M.; Boldu, J.L.; Chen, Y.; Orera, V.M.

1984-09-28

A method for preparing reversible-photochromic magnesium oxide (MgO) crystals is disclosed. Single crystals of MgO doped with both lithium (Li) and nickel (Ni) are grown by a conventional arc fusion method. The as-grown crystals are characterized by an amber coloration. The crystals lose the amber coloration and become photochromic when they are thermochemically reduced by heating at temperatures greater then 1000/sup 0/K in a hydrogen atmosphere. Alternate irradiation with uv and visible light result in rejuvenation and bleaching of the amber coloration, respectively.

Growth of bulk ZnO crystals by self-selecting CVT method

NASA Astrophysics Data System (ADS)

Fan, Long; Jiang, Tao; Xiao, TingTing; Chen, Jie; Peng, Liping; Wang, Xuemin; Yan, Dawei; Wu, Weidong

2018-05-01

Bulk ZnO crystals were grown by self-selecting CVT method using carbon as the transport agent. The crystal growth process took place on the top of the polycrystalline source material, and deep-red colored ZnO crystals of several millimeters were obtained. The as-grown crystals were characterized by X-ray diffraction (XRD), Energy Dispersive Spectrometer (EDS), Raman scattering (RS) spectroscopy, visible-near infrared (VIS-NIR) spectrophotometer and room temperature photoluminescence (PL) spectroscopy. XRD results indicate good crystallinity of the ZnO crystal. The EDS analysis shows that the crystal has a stoichiometry ratio Zn: O = 52: 48. The results suggest the existence of native defects of oxygen vacancies (OV) in the as-grown ZnO samples, which is caused by the stoichiometry shift to Zn-rich.

Neutralization of Hydroxide Ion in Melt-Grown NaCl Crystals

NASA Technical Reports Server (NTRS)

Otterson, Dumas A.

1961-01-01

Many recent studies of solid-state phenomena, particularly in the area of crystal imperfections, have involved the use of melt-grown NaCl single crystals. Quite often trace impurities in these materials have had a prominent effect on these phenomena. Trace amounts of hydroxide ion have been found in melt-grown NaCl crystals. This paper describes a nondestructive method of neutralizing the hydroxide ion in such crystals. Crystals of similar hydroxide content are maintained at an elevated temperature below the melting point of NaCl in a flowing atmosphere containing. dry hydrogen chloride. Heat treatment is continued until an analysis of the test specimens shows no excess hydroxide ion. A colorimetric method previously described4 is used for this analysis.

Potassium-cobalt sulphate crystal growth assisted by low frequency vibrations

NASA Astrophysics Data System (ADS)

Sadovsky, A.; Ermochenkov, I.; Dubovenko, E.; Sukhanova, E.; Bebyakin, M.; Dubov, V.; Avetissov, I.

2018-02-01

Single crystals of K2Co(SO4)2·6H2O were grown from solution using the temperature reduction method enhanced by the axial low frequency vibration control technique (AVC-technique). Physical modeling of heat-mass transfer in solution under the AVC action was performed. The growth rate of the AVC grown crystal was found to be twice that of the crystal grown under natural convection conditions. Analysis of spectral characteristics (absorption and Raman spectra) as well as structural properties (dislocation density and microhardness) of the grown crystals showed the significant superiority of the AVC technique for the growth of K2Co(SO4)2·6H2O crystals.

Crystal growth and piezoelectric properties of Ca3Ta(Ga0.9Sc0.1)3Si2O14 bulk single crystal

NASA Astrophysics Data System (ADS)

Igarashi, Yu; Yokota, Yuui; Ohashi, Yuji; Inoue, Kenji; Yamaji, Akihiro; Shoji, Yasuhiro; Kamada, Kei; Kurosawa, Shunsuke; Yoshikawa, Akira

2018-03-01

Ca3Ta(Ga0.9Sc0.1)3Si2O14 langasite-type single crystal with a diameter of 1 in. was grown by Czochralski (Cz) method. Obtained crystal had good crystallinity and its lattice constants exceeded those of Ca3TaGa3Si2O14 (CTGS) according to the X-ray analysis. A crack-free specimen cut from the grown crystal was used for the measurements of dielectric constant ε11T/ε0, electromechanical coupling factor k12, and piezoelectric constant d11. The accuracies of these measurements were better than those for the crystal grown by micro-pulling-down (μ-PD) method. Substitution of Ga with Sc resulted modification of these constants in the directions opposite to those observed after partial substitution of Ga (of CTGS) with Al. This suggests that increase of |d14| was most probably associated with enlargement of average size of the Ga sites. The crystal reported here had greater dimensions as compared to analogous crystals grown by the μ-PD method. As a result, accuracy of determination of acoustic constants of this material may be improved.

Growth and characterization of CaCu3Ti4O12 single crystals

NASA Astrophysics Data System (ADS)

Kim, Hui Eun; Yang, Sang-don; Lee, Jung-Woo; Park, Hyun Min; Yoo, Sang-Im

2014-12-01

The CaCu3Ti4O12 (CCTO) single crystals could be grown from the melt with the nominal composition of Ca:Cu:Ti=1:59:20 in a platinum (Pt) crucible using a self-flux method. The flux-grown CCTO single crystals have well-developed {100} habit planes, and their compositions are close to the ratio of Ca:Cu:Ti=1:3:4. Interestingly, flux-grown CCTO single crystals exhibited two different back reflection Laue patterns; one exhibited only [100] cubic Laue patterns, and the other showed not only [100] cubic Laue patterns but also the satellite spots related to the twin boundary, implying that twin-free CCTO single crystals can be grown by the self-flux method. Both the dielectric constants and losses of twinned CCTO single crystal are significantly higher than those of untwined CCTO crystal at relatively low frequency regime (<10 kHz), suggesting that the dielectric property is sensitive to the twin boundary.

Studies on the growth aspects, structural, thermal, dielectric and third order nonlinear optical properties of solution grown 4-methylpyridinium p-nitrophenolate single crystal

NASA Astrophysics Data System (ADS)

Devi, S. Reena; Kalaiyarasi, S.; Zahid, I. MD.; Kumar, R. Mohan

2016-11-01

An ionic organic optical crystal of 4-methylpyridinium p-nitrophenolate was grown from methanol by slow evaporation method at ambient temperature. Powder and single crystal X-ray diffraction studies revealed the crystal system and its crystalline perfection. The rocking curve recorded from HRXRD study confirmed the crystal quality. FTIR spectral analysis confirmed the functional groups present in the title compound. UV-visible spectral study revealed the optical window and band gap of grown crystal. The thermal, electrical and surface laser damage threshold properties of harvested crystal were examined by using TGA/DTA, LCR/Impedance Analyzer and Nd:YAG laser system respectively. The third order nonlinear optical property of grown crystal was elucidated by Z-scan technique.

Growth and characterization of diammonium copper disulphate hexahydrate single crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siva Sankari, R.; Perumal, Rajesh Narayana, E-mail: r.shankarisai@gmail.com

2014-03-01

Graphical abstract: Diammonium copper disulphate hexahydrate (DACS) is one of the most promising inorganic dielectric crystals with exceptional mechanical properties. Good quality crystals of DACS were grown by using solution method in a period of 30 days. The grown crystals were subjected to single crystal X-ray diffraction analysis in order to establish their crystalline nature. Thermo gravimetric, differential thermal analysis, FTIR, and UV–vis–NIR analysis were performed for the crystal. Several solid state physical parameters have been determined for the grown crystals. The dielectric constant and the dielectric loss and AC conductivity of the grown crystal were studied as a functionmore » of frequency and temperature has been calculated and plotted. - Highlights: • Diammonium copper disulphate is grown for the first time and CCDC number obtained. • Thermal analysis is done to see the stability range of the crystals. • Band gap and UV cut off wavelength of the crystal are determined to be 2.4 eV and 472.86 nm, respectively. • Dielectric constant, dielectric loss and AC conductivity are plotted as a function of applied field. - Abstract: Diammonium copper disulphate hexahydrate is one of the most promising inorganic crystals with exceptional dielectric properties. A good quality crystal was harvested in a 30-day period using solution growth method. The grown crystal was subjected to various characterization techniques like single crystal X-ray diffraction analysis, thermo gravimetric, differential thermal analysis, FTIR, and UV–vis–NIR analysis. Unit cell dimensions of the grown crystal have been identified from XRD studies. Functional groups of the title compounds have been identified from FTIR studies. Thermal stability of the samples was checked by TG/DTA studies. Band gap of the crystal was calculated. The dielectric constant and dielectric loss were studied as a function of frequency of the applied field. AC conductivity was plotted as a function of temperature.« less

Thermal, mechanical, optical and dielectric properties of piperazinium hydrogen phosphite monohydrate NLO single crystal

NASA Astrophysics Data System (ADS)

Rajkumar, R.; Praveen Kumar, P.

2018-05-01

Optical transparent crystal of piperazinium hydrogen phosphite monohydrate (PHPM) was grown by slow evaporation method. The grown crystal was characterized by single crystal X-ray diffraction analysis and the crystal belongs to monoclinic system. The functional groups present in PHPM crystal were confirmed by FTIR analysis. UV-Visible spectrum shows that the PHPM crystal is transparent in the visible region. The mechanical behavior of PHPM crystal was characterized by Vickers hardness test. Thermal stability of PHPM crystal was analyzed by thermogravimetric analysis. Dielectric studies were also carried out for the grown crystal. The third-order nonlinear parameters such as nonlinear refractive index and nonlinear absorption coefficient have been calculated using Z scan technique.

Luminescence and Scintillation Properties of Czochralski Grown LYGBO Crystals

NASA Astrophysics Data System (ADS)

Fawad, U.; Kim, Hong Joo; Park, H.; Kim, Sunghwan; Khan, Sajid

2016-06-01

Mixed crystals Li6YxGd1-x(BO3)3:Ce3+ (LYGBO) (where, x = 0.0, 0.2, 0.5, 0.8, 1.0) are grown by using Czochralski method with different proportions of Li6Y(BO3)3 and Li6Gd(BO3)3. All crystals are doped with 3 mole% optimized concentrations of Ce3+ ions. The grown crystals are 20-70 mm in length and 5-10 mm in diameter. Detailed sintering and crystal growth procedure is presented in this study. The required phase of the grown crystals is confirmed by powder X-ray diffraction (XRD) analysis. Ultraviolet (UV) photoluminescence and X-ray induced luminescence of the grown crystals at room temperature are measured. Various scintillation properties such as energy resolution, light yield, α/β ratio and fluorescence decay time under the excitation by 137Cs γ-ray and 241Am particles are also presented.

Optical characteristics of novel bulk and nanoengineered laser host materials

NASA Astrophysics Data System (ADS)

Prasad, Narasimha S.; Sova, Stacey; Kelly, Lisa; Bevan, Talon; Arnold, Bradley; Cooper, Christopher; Choa, Fow-Sen; Singh, N. B.

2018-02-01

The hexagonal apatite single crystals have been investigated for their applications as laser host materials. Czochralksi and flux growth methods have been utilized to obtain single crystals. For low temperature processing (<100 0C), several techniques for crystal growth have been developed. The hexagonal apatite structure (space group P63/m) is characteristic of several compounds, some of which have extremely interesting and useful properties as laser hosts and bone materials. Calcium lanthanum silicate (Nd-doped) and lanthanum aluminate material systems were studied in detail. Nanoengineered calcium and lanthanum based silicates were synthesized by a solution method and their optical and morphological characteristics were compared with Czochralski grown bulk hydroxyapatite single crystals. Materials were evaluated by absorbance, fluorescence and Raman characteristics. Neodymium, iron and chromium doped crystals grown by a solution method showed weak but similar optical properties to that of Czochralski grown single crystals.

Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals.

PubMed

Rose, A S J Lucia; Selvarajan, P; Perumal, S

2011-10-15

Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm×12 mm×8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied. Copyright © 2011 Elsevier B.V. All rights reserved.

Growth, density functional theory (DFT) and spectral studies on L-2-aminobutyric acid -biologically active material

NASA Astrophysics Data System (ADS)

Usha, C.; Santhakumari, R.; Meenakshi, R.; Jayasree, R.; Bhuvaneswari, M.

2017-12-01

Single crystal of L-2-aminobutyric acid (ABA) was grown from water by slow evaporation at room temperature. The crystalline nature of the grown crystal was confirmed using powder X-ray diffraction studies. The grown crystal was subjected to FT-IR, FT-Raman, 1H NMR and 13C NMR spectral analyses to confirm the presence of functional group and molecular structure respectively. Thermal properties were investigated by thermogravimetric and differential thermal analyses. The range and percentage of optical transmission was ascertained by recording UV-vis-NIR spectrum. The electronic charge distribution and reactivity of the molecules within the crystal were studied by HOMO and LUMO analysis and the molecular electrostatic potential (MEP) of the grown crystal was performed using the B3LYP method. The anti-bacterial activities of the crystal were performed by disk diffusion method against the standard bacteria E. coli. The crystal exhibits good anti-bacterial activity. Second harmonic generation efficiency of the powdered ABA crystal was tested using Nd:YAG laser and it is found to be ∼3.3 times that of potassium dihydrogen orthophosphate.

Synthesis, crystal structure, thermal and nonlinear optical properties of new metal-organic single crystal: Tetrabromo (piperazinium) zincate (II) (TBPZ)

NASA Astrophysics Data System (ADS)

Boopathi, K.; Babu, S. Moorthy; Ramasamy, P.

2018-04-01

Tetrabromo (piperazinium) zincate, a new metal-organic crystal has been synthesized and its single crystal grown by slow evaporation method. The grown crystal has characterized by structural, spectral, thermal, linear and nonlinear optical properties. Single crystal X-ray diffractions study reveals that grown crystal belongs to orthorhombic crystal system with space group P212121. The presence of functional groups is identified by FT-IR spectral analysis. Thermal stability of the crystal was ascertained by TG-DTA measurement. The second order harmonic generation efficiency was measured using Kurtz and Perry technique and it was found to be 1.5 times that of KDP.

DC electrical conductivity measurements for pure and titanium oxide doped KDP Crystals grown by gel medium

NASA Astrophysics Data System (ADS)

Mareeswaran, S.; Asaithambi, T.

2016-10-01

Now a day's crystals are the pillars of current technology. Crystals are applied in various fields like fiber optic communications, electronic industry, photonic industry, etc. Crystal growth is an interesting and innovative field in the subject of physics, chemistry, material science, metallurgy, chemical engineering, mineralogy and crystallography. In recent decades optically good quality of pure and metal doped KDP crystals have been grown by gel growth method in room temperature and its characterizations were studied. Gel method is a very simple and one of the easiest methods among the various crystal growth methods. Potassium dihydrogen phosphate KH2PO4 (KDP) continues to be an interesting material both academically and technologically. KDP is a delegate of hydrogen bonded materials which possess very good electrical and nonlinear optical properties in addition to interesting electro-optic properties. We made an attempt to grow pure and titanium oxide doped KDP crystals with various doping concentrations (0.002, 0.004, 0.006, 0.008 and 0.010) using gel method. The grown crystals were collected after 20 days. We get crystals with good quality and shaped crystals. The dc electrical conductivity (resistance, capacitance and dielectric constant) values of the above grown crystals were measured at two different frequencies (1KHz and 100 Hz) with a temperature range of 500C to 1200C using simple two probe setup with Q band digital LCR meter present in our lab. The electrical conductivity increases with the increase of temperature. Dielectric constants value of titanium oxide doped KDP crystal was slightly decreased compared with pure KDP crystals. Results were discussed in details.

Crystal growth, structural, thermal and mechanical behavior of l-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) single crystals.

PubMed

Mahadevan, M; Ramachandran, K; Anandan, P; Arivanandhan, M; Bhagavannarayana, G; Hayakawa, Y

2014-12-10

Single crystals of l-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) have been grown successfully from the solution of l-arginine and 4-nitrophenol. Slow evaporation of solvent technique was adopted to grow the bulk single crystals. Single crystal X-ray diffraction analysis confirms the grown crystal has monoclinic crystal system with space group of P21. Powder X-ray diffraction analysis shows the good crystalline nature. The crystalline perfection of the grown single crystals was analyzed by HRXRD by employing a multicrystal X-ray diffractometer. The functional groups were identified from proton NMR spectroscopic analysis. Linear and nonlinear optical properties were determined by UV-Vis spectrophotometer and Kurtz powder technique respectively. It is found that the grown crystal has no absorption in the green wavelength region and the SHG efficiency was found to be 2.66 times that of the standard KDP. The Thermal stability of the crystal was found by obtaining TG/DTA curve. The mechanical behavior of the grown crystal has been studied by Vicker's microhardness method. Copyright © 2014 Elsevier B.V. All rights reserved.

Growth and characterization of organic material 4-dimethylaminobenzaldehyde single crystal.

PubMed

Jebin, R P; Suthan, T; Rajesh, N P; Vinitha, G; Madhusoodhanan, U

2015-01-25

The organic material 4-dimethylaminobenzaldehyde single crystals were grown by slow evaporation technique. The grown crystal was confirmed by the single crystal and powder X-ray diffraction analyses. The functional groups of the crystal have been identified from the Fourier Transform Infrared (FTIR) and FT-Raman studies. The optical property of the grown crystal was analyzed by UV-Vis-NIR and photoluminescence (PL) spectral measurements. The thermal behavior of the grown crystal was analyzed by thermogravimetric (TG) and differential thermal analyses (DTA). Dielectric measurements were carried out with different frequencies by using parallel plate capacitor method. The third order nonlinear optical properties of 4-dimethylaminobenzaldehyde was measured by the Z-scan technique using 532 nm diode pumped continuous wave (CW) Nd:YAG laser. Copyright © 2014 Elsevier B.V. All rights reserved.

Study on optical properties of L-valine doped ADP crystal

NASA Astrophysics Data System (ADS)

Shaikh, R. N.; Anis, Mohd.; Shirsat, M. D.; Hussaini, S. S.

2015-02-01

Single crystal of L-valine doped ammonium dihydrogen phosphate has been grown by slow evaporation method at room temperature. The crystalline nature of the grown crystal was confirmed using powder X-ray diffraction technique. The different functional groups of the grown crystal were identified using Fourier transform infrared analysis. The UV-visible studies were employed to examine the high optical transparency and influential optical constants for tailoring materials suitability for optoelectronics applications. The cutoff wavelength of the title crystal was found to be 280 nm with wide optical band gap of 4.7 eV. The dielectric measurements were carried to determine the dielectric constant and dielectric loss at room temperature. The grown crystal has been characterized by thermogravimetric analysis. The second harmonic generation efficiency of the grown crystal was determined by the classical Kurtz powder technique and it is found to be 1.92 times that of potassium dihydrogen phosphate. The grown crystal was identified as third order nonlinear optical material employing Z-scan technique using He-Ne laser operating at 632.8 nm.

Growth of NBT-BT single crystals by flux method and their structural, morphological and electrical characterizations

NASA Astrophysics Data System (ADS)

Kanuru, Sreenadha Rao; Baskar, K.; Dhanasekaran, R.; Kumar, Binay

2016-05-01

In this paper, one of the important, eco-friendly polycrystalline material, (1-x)(Na0.5Bi0.5)TiO3 (NBT) - xBaTiO3 (BT) of different compositions (x=0.07, 0.06 and 0.05 wt%) around the morphotropic phase boundary (MPB) were synthesized by solid state reaction technique. And the single crystals with 13×7×7 mm3, 12×12×7 mm3 and 10×7×4 mm3 dimensions were grown by self flux method. The morphology, crystal structure and unit-cell parameters have been studied and the monoclinic phase has been identified for 0.07 wt% of BT. Higher BT concentration changes the crystal habit and the mechanism has been studied clearly. Raman spectroscopy at room-temperature confirms the presence of functional groups. The quality of the as grown single crystals was examined by high resolution x-ray diffraction analysis. The dielectric properties of the as grown crystals were investigated in the frequency range of 20 Hz-2 MHz from room temperature to 450 °C. The broad dielectric peak and frequency dispersion demonstrates the relaxor behavior of grown crystals. The dielectric constant (εr), transition temperature (Tm), and depolarization temperature (Td) of the grown crystals are found to be comparatively good. The diffusive factor (γ) from Curie-Weiss law confirms the as grown NBT-BT single crystals are relaxor in nature.

Studies on 2-amino-5-nitropyridinium nitrate (2A5NPN): A semi-organic third order nonlinear optical single crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sivasubramani, V.; Pandian, Muthu Senthil, E-mail: senthilpandianm@ssn.edu.in; Ramasamy, P.

2016-05-23

2-amino-5-nitropyridinium nitrate (2A5NPN) is a semi-organic nonlinear optical crystal and optically good quality 2A5NPN single crystals were successfully grown by slow evaporation solution growth technique (SEST) at ambient temperature. The crystallographic structure of the grown crystal was determined by single crystal X-Ray diffraction analysis and it belongs to Monoclinic crystal system with centro symmetric crystalline nature. The crystallinity of the grown crystal was confirmed by powder X-ray diffraction analysis. The other physical properties of grown crystals are also characterized using TG-DTA, UV-Visible NIR, chemical etching, photoconductivity and Z-scan measurements. The Z-scan method reveals that the 2A5NPN crystal possesses multi photonmore » absorption behaviour and the significantly higher third order susceptibility and it is a promising potential NLO material.« less

Depth-Resolved Cathodoluminescence Study of Annealed Silicon Implanted Gallium Arsenide.

DTIC Science & Technology

1982-12-01

samples were Cr doped semi-insulat- ing GaAs crystals grown using the horizontal Bridgman method. Nine samples were prepared for this study, four were...function of depth. Cathodoluminescence was the excitation method. The crystals studied were grown using the horizontal Bridgman method. Four samples were...achieved by taking spectral data and successively chemically etching the surface of the crystal in 250 R steps. No new peaks were observed in the

Crystal growth, structural, low temperature thermoluminescence and mechanical properties of cubic fluoroperovskite single crystal (LiBaF3)

NASA Astrophysics Data System (ADS)

Daniel, D. Joseph; Ramasamy, P.; Ramaseshan, R.; Kim, H. J.; Kim, Sunghwan; Bhagavannarayana, G.; Cheon, Jong-Kyu

2017-10-01

Polycrystalline compounds of LiBaF3 were synthesized using conventional solid state reaction route and the phase purity was confirmed using powder X-ray diffraction technique. Using vertical Bridgman technique single crystal was grown from melt. Rocking curve measurements have been carried out to study the structural perfection of the grown crystal. The single peak of diffraction curve clearly reveals that the grown crystal was free from the structural grain boundaries. The low temperature thermoluminescence of the X-ray irradiated sample has been analyzed and found four distinguishable peaks having maximum temperatures at 18, 115, 133 and 216 K. Activation energy (E) and frequency factor (s) for the individual peaks have been studied using Peak shape method and the computerized curve fitting method combining with the Tmax- TStop procedure. Nanoindentation technique was employed to study the mechanical behaviour of the crystal. The indentation modulus and Vickers hardness of the grown crystal have values of 135.15 GPa and 680.81 respectively, under the maximum indentation load of 10 mN.

Growth and characterization of benzaldehyde 4-nitro phenyl hydrazone (BPH) single crystal: A proficient second order nonlinear optical material

NASA Astrophysics Data System (ADS)

Saravanan, M.; Abraham Rajasekar, S.

2016-04-01

The crystals (benzaldehyde 4-nitro phenyl hydrazone (BPH)) appropriate for NLO appliance were grown by the slow cooling method. The solubility and metastable zone width measurement of BPH specimen was studied. The material crystallizes in the monoclinic crystal system with noncentrosymmetric space group of Cc. The optical precision in the whole visible region was found to be excellent for non-linear optical claim. Excellence of the grown crystal is ascertained by the HRXRD and etching studies. Laser Damage Threshold and Photoluminescence studies designate that the grown crystal contains less imperfection. The mechanical behaviour of BPH sample at different temperatures was investigated to determine the hardness stability of the grown specimen. The piezoelectric temperament and the relative Second Harmonic Generation (for diverse particle sizes) of the material were also studied. The dielectric studies were executed at varied temperatures and frequencies to investigate the electrical properties. Photoconductivity measurement enumerates consummate of inducing dipoles due to strong incident radiation and also divulge the nonlinear behaviour of the material. The third order nonlinear optical properties of BPH crystals were deliberate by Z-scan method.

Crystal growth, physical properties and computational insights of semi-organic non-linear optical crystal diphenylguanidinium perchlorate grown by conventional solvent evaporation method

NASA Astrophysics Data System (ADS)

Kajamuhideen, M. S.; Sethuraman, K.; Ramamurthi, K.; Ramasamy, P.

2018-02-01

A splendid nonlinear optical single crystals diphenylguanidinium perchlorate (DPGP) was lucratively grown by low cost solvent evaporation method with the dimensions of 8 × 4 × 2 mm3. Structural and morphological studies of grown crystal were confirmed using X-ray diffraction studies. The presence of diverse functional groups was identified using FTIR and RAMAN studies. The molecular structure of a grown crystal was inveterate by NMR studies. The optical transmittance of DPGP crystal was analyzed using UV-vis-NIR studies. Photoluminescence spectrum shows sharp, well defined emission peak at 388 nm. Thermal studies assign that adduct is stable with the melting point of 164 °C. Microhardness studies declare that DPGP crystal belongs to the soft material class and their yield strength and elastic stiffness constant values were evaluated. Photoconductivity studies revealed the negative photoconductive nature of DPGP crystal. Second harmonic generation (SHG) efficiency of the DPGP crystal was 1.4 times that of potassium dihydrogen phosphate. Etching studies were carried out for different etching time. The dielectric studies were performed at different frequency. Laser damage threshold properties of DPGP crystal were examined using Nd:YAG laser system. The HOMO-LUMO energy gap evident the charge transfer interaction of the molecule. The calculated first order hyperpolarizability value is 5 times greater than that of urea. Thus, the grown DPGP single crystals are well suited for NLO device fabrications.

Synthesis and structural study of 4-(2-chlorophenyl)-2-ethoxy-5,6,7,8,9,10-hexahydrocycloocta[B]pyridine-3-carbonitrile

NASA Astrophysics Data System (ADS)

Fathima, K. Saiadali; Vasumathi, M.; Anitha, K.

2016-05-01

The novel organic material C20H21ClN2O was synthesized by One-Pot synthesis method and the single crystals were grown by slow evaporation solution growth technique. The crystal structure was elucidated by subjecting the grown crystals to the single crystal x-ray diffraction analysis and was refined by full matrix least-squares method to R=0.039 for 2746 reflections. Crystal system of the grown crystal was found to be monoclinic with the space group P21/a and a=9.196(4) Å, b=13.449(4) Å, c=14.818(4) Å, β= 101.542(3)°, V=1795.6(11) Å3 and Z=4. In this crystal structure, cyclooctanone prefers to reside in a chair-boat conformation. The structure is stabilized by attractive molecular force such as CH/π interaction called hydrophobic interaction.

Structural, optical, mechanical and dielectric studies of pure and doped L-Prolinium trichloroacetate single crystals.

PubMed

Renuka, N; Ramesh Babu, R; Vijayan, N; Vasanthakumar, Geetha; Krishna, Anuj; Ramamurthi, K

2015-02-25

In the present work, pure and metal substituted L-Prolinium trichloroacetate (LPTCA) single crystals were grown by slow evaporation method. The grown crystals were subjected to single crystal X-ray diffraction (XRD), powder X-ray diffraction, FTIR, UV-Visible-NIR, hardness, photoluminescence and dielectric studies. The dopant concentration in the crystals was measured by inductively coupled plasma (ICP) analysis. Single crystal X-ray diffraction studies of the pure and metal substituted LPTCA revealed that the grown crystals belong to the trigonal system. Ni(2+) and Co(2+) doping slightly altered the lattice parameters of LPTCA without affecting the basic structure of the crystal. FTIR spectral analysis confirms the presence of various functional groups in the grown crystals. The mechanical behavior of pure and doped crystals was analyzed by Vickers's microhardness test. The optical transmittance, dielectric and photoluminescence properties of the pure and doped crystals were analyzed. Copyright © 2014 Elsevier B.V. All rights reserved.

Growth and characterization of Methyl 2-amino-5-bromobenzoate crystal for NLO applications

NASA Astrophysics Data System (ADS)

Parthasarathy, M.; Gopalakrishnan, R.

2012-11-01

Good quality single crystal of organic Methyl 2-amino-5-bromobenzoate (M2A5B) was grown using slow evaporation solution growth technique. The grown crystal was confirmed by single crystal X-ray diffraction. The functional groups and vibrational frequencies were identified using FT-IR and FT-Raman spectral analyses. The presence of hydrogen and carbon atoms in the grown sample was confirmed with proton and carbon NMR spectral studies. The optical energy band gap of the title compound is found to be 2.7 eV from the optical transmission spectra. The refractive indices nx, ny, and nz were found to be 1.569, 1.587 and 1.600, respectively using Brewster's angle method. The melting point of the material obtained with melting point apparatus is 74 °C. Thermal stability of the grown crystal was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The mechanical behaviour of the grown crystal was analyzed with Vicker's microhardness tester. The particle size dependent second harmonic generation efficiency for M2A5B was evaluated by Kurtz-Perry powder method using Nd:YAG laser, which established the existence of phase matching.

Molecular Dynamic Simulation of Space and Earth-Grown Crystal Structures of Thermostable T1 Lipase Geobacillus zalihae Revealed a Better Structure.

PubMed

Ishak, Siti Nor Hasmah; Aris, Sayangku Nor Ariati Mohamad; Halim, Khairul Bariyyah Abd; Ali, Mohd Shukuri Mohamad; Leow, Thean Chor; Kamarudin, Nor Hafizah Ahmad; Masomian, Malihe; Rahman, Raja Noor Zaliha Raja Abd

2017-09-25

Less sedimentation and convection in a microgravity environment has become a well-suited condition for growing high quality protein crystals. Thermostable T1 lipase derived from bacterium Geobacillus zalihae has been crystallized using the counter diffusion method under space and earth conditions. Preliminary study using YASARA molecular modeling structure program for both structures showed differences in number of hydrogen bond, ionic interaction, and conformation. The space-grown crystal structure contains more hydrogen bonds as compared with the earth-grown crystal structure. A molecular dynamics simulation study was used to provide insight on the fluctuations and conformational changes of both T1 lipase structures. The analysis of root mean square deviation (RMSD), radius of gyration, and root mean square fluctuation (RMSF) showed that space-grown structure is more stable than the earth-grown structure. Space-structure also showed more hydrogen bonds and ion interactions compared to the earth-grown structure. Further analysis also revealed that the space-grown structure has long-lived interactions, hence it is considered as the more stable structure. This study provides the conformational dynamics of T1 lipase crystal structure grown in space and earth condition.

Dopant Segregation in Earth- and Space-Grown InP Crystals

NASA Astrophysics Data System (ADS)

Danilewsky, Andreas Nikolaus; Okamoto, Yusuke; Benz, Klaus Werner; Nishinaga, Tatau

1992-07-01

Macro- and microsegregation of sulphur in InP crystals grown from In solution by the travelling heater method under microgravity and normal gravity are analyzed using spatially resolved photoluminescence. Whereas the macrosegregation in earth- as well as space-grown crystals is explained by conventional steady-state models based on the theory of Burton, Prim and Slichter (BPS), the microsegregation can only be understood in terms of the non-steady-state step exchange model.

Growth and characterization of unidirectional benzil single crystal for photonic applications

NASA Astrophysics Data System (ADS)

Saranraj, A.; Thirupathy, J.; Dhas, S. Sahaya Jude; Jose, M.; Vinitha, G.; Dhas, S. A. Martin Britto

2018-06-01

Organic nonlinear optical benzil single crystal of fine quality with the dimensions of 168 × 14 mm2 was successfully grown in (100) plane from saturated solution by unidirectional SR method. The structural identity of the grown crystal was confirmed by powder XRD. High-resolution X-ray diffraction analysis indicates the crystalline perfection of the grown benzil crystal. The optical analysis was carried out by UV-visible spectroscopy which shows that the benzil crystal's cut off wavelength is 437 nm. The dielectric constant and dielectric loss of benzil crystal are found to be very much depending upon temperature and frequency. Ferroelectric nature of grown crystal was identified by P- E hysteresis analysis and to find the values of spontaneous polarization and coercive field. The laser damage threshold energy was studied with the help of Nd:YAG laser. The presence of third harmonic generation was identified by z-scan techniques.

The density and compositional analysis of titanium doped sapphire single crystal grown by the Czocharlski method

NASA Astrophysics Data System (ADS)

Kusuma, H. H.; Ibrahim, Z.; Othaman, Z.

2018-03-01

Titanium doped sapphire (Ti:Al2O3) crystal has attracted attention not only as beautiful gemstones, but also due to their applications as high power laser action. It is very important crystal for tunable solid state laser. Ti:Al2O3 crystals have been success grown using the Czocharlski method with automatic diameter control (ADC) system. The crystals were grown with different pull rates. The structure of the crystal was characterized with X-Ray Diffraction (XRD). The density of the crystal was measurement based on the Archimedes principle and the chemical composition of the crystal was confirmed by the Energy Dispersive X-ray (EDX) Spectroscopy. The XRD patterns of crystals are showed single main peak with a high intensity. Its shows that the samples are single crystal. The Ti:Al2O3 grown with different pull rate will affect the distribution of the concentration of dopant Ti3+ and densities on the sapphire crystals boules as well on the crystal growth process. The increment of the pull rate will increase the percentage distribution of Ti3+ and on the densities of the Ti:Al2O3 crystal boules. This may be attributed to the speed factor of the pull rate of the crystal that then caused changes in the heat flow in the furnace and then causes the homogeneities is changed of species distribution of atoms along crystal.

Growth and characterization of AgGa0.5In0.5Se2 single crystals by modified vertical Bridgman method

NASA Astrophysics Data System (ADS)

Vijayakumar, P.; Ramasamy, P.

2016-05-01

AgGa0.5In0.5Se2 single crystal was grown using a double wall quartz ampoule with accelerated crucible rotation technique by modified vertical Bridgman method. The structural perfection was measured using HRXRD. The grown single crystal composition was measured using ICP-OES analysis and compositional uniformities were measured using Raman spectroscopy analysis. Photoconductivity measurements confirm the positive photoconducting nature.

Passive particle dosimetry. [silver halide crystal growth

NASA Technical Reports Server (NTRS)

Childs, C. B.

1977-01-01

Present methods of dosimetry are reviewed with emphasis on the processes using silver chloride crystals for ionizing particle dosimetry. Differences between the ability of various crystals to record ionizing particle paths are directly related to impurities in the range of a few ppm (parts per million). To understand the roles of these impurities in the process, a method for consistent production of high purity silver chloride, and silver bromide was developed which yields silver halides with detectable impurity content less than 1 ppm. This high purity silver chloride was used in growing crystals with controlled doping. Crystals were grown by both the Czochalski method and the Bridgman method, and the Bridgman grown crystals were used for the experiments discussed. The distribution coefficients of ten divalent cations were determined for the Bridgman crystals. The best dosimeters were made with silver chloride crystals containing 5 to 10 ppm of lead; other impurities tested did not produce proper dosimeters.

Bridgman growth of lead potassium niobate crystals

NASA Astrophysics Data System (ADS)

Fan, Shiji; Sun, Renying; Lin, Yafang; Wu, Jindi

1999-03-01

Lead potassium niobate Pb 2KNb 5O 15 (PKN) crystals with tetragonal tungsten bronze (TTB) structure have been grown by the modified Bridgman (BR) method. Nearly sealed Pt crucibles and small temperature gradients in the Bridgman furnace can limit volatilization of PbO and cracking of as-grown PKN crystals. Transparent PKN crystals of 1 inch diameter by ˜2 inch length with brownish color have been grown successfully at a crucible lowering rate <0.5 mm/h and a temperature gradient of 10-15°C/cm across the solid-liquid interface. Coupling between twins and growth directions of the crystal is also discussed.

Synthesis, characterization and anti-microbial activity of pure, Cu2+ and Cd2+ doped organic NLO l-arginine trifluoroacetate single crystals

NASA Astrophysics Data System (ADS)

Prasanyaa, T.; Haris, M.; Jayaramakrishnan, V.; Amgalan, M.; Mathivanan, V.

2013-10-01

Optically transparent Cu2+ and Cd2+ doped l-arginine trifluoroacetate (LATF) single crystals were grown from its aqueous solution using the slow solvent evaporation technique. The grown crystals were characterized by powder x-ray diffraction to confirm the monoclinic crystal structure. The percentage of transmittance measured using the ultraviolet-visible-near infrared spectrophotometer was found to be more than 80% for doped crystals. The functional group analysis of the grown crystals has been made by Fourier transform infrared spectroscopy. Thermogravimetric/differential thermal analysis was performed for the grown crystals. An atomic absorption study was carried out to determine the presence of Cu2+ and Cd2+. The hardness of the grown crystals was assessed and the results show a significant variation in the hardness value between the pure and doped LATF crystals. The second harmonic generation measurements show that Cu2+ doped LATF is 2.8 times greater and Cd2+ doped is 2.6 times greater than KDP. The anti-bacterial and anti-fungal activities of the title compound were performed using the disc diffusion method against standard bacteria Escherichia coli, Xanthomonas oryzae and against the fungus Aspergillus niger and Aspergillus flavus.

Synthesis and structural study of 4-(2-chlorophenyl)-2-ethoxy-5,6,7,8,9,10-hexahydrocycloocta[B] pyridine-3-carbonitrile

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fathima, K. Saiadali; Vasumathi, M.; Anitha, K., E-mail: singlecrystalxrd@gmail.com

2016-05-23

The novel organic material C{sub 20}H{sub 21}ClN{sub 2}O was synthesized by One-Pot synthesis method and the single crystals were grown by slow evaporation solution growth technique. The crystal structure was elucidated by subjecting the grown crystals to the single crystal x-ray diffraction analysis and was refined by full matrix least-squares method to R=0.039 for 2746 reflections. Crystal system of the grown crystal was found to be monoclinic with the space group P2{sub 1}/a and a=9.196(4) Å, b=13.449(4) Å, c=14.818(4) Å, β= 101.542(3)°, V=1795.6(11) Å{sup 3} and Z=4. In this crystal structure, cyclooctanone prefers to reside in a chair-boat conformation. Themore » structure is stabilized by attractive molecular force such as CH/π interaction called hydrophobic interaction.« less

Synthesis aspects, structural, spectroscopic, antimicrobial and room temperature ferromagnetism of zinc iodide complex with Schiff based ligand

NASA Astrophysics Data System (ADS)

Shakila, K.; Kalainathan, S.

2015-01-01

In this paper, we report the successful growth of complex compound of zinc iodide with thiocarbamide by slow evaporation method. The single crystal XRD study reveals that the crystal belongs to monoclinic system with centrosymmetric space group and powder XRD analysis shows that the perfect crystalline nature of the crystal. The presence of functional group and element were confirmed from FT-IR and EDAX analysis. Optical absorbance of the grown crystal was studied by UV-Vis spectrophotometer. The optical constants were calculated from the optical absorbance data such as refractive index (n), extinction coefficient (K) and reflectance (R). The optical band gap (Eg) of thiocarbamide zinc iodide crystal is 4.22 eV. The magnetic properties of grown crystal have been determined by Vibrating Sample Magnetometry (VSM). Room temperature magnetization revealed a ferromagnetic behaviour for the grown crystal. The antibacterial and antifungal activities of the title compound were performed by well diffusion method and MIC method against the standard bacteria like Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and against fungus like Aspergillus niger, Rhizopus sps and Penicillium sps. Thermal behaviour of the crystal has been investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA).

Growth and antimicrobial studies of γ-glycine crystal grown using CuSO4

NASA Astrophysics Data System (ADS)

Vijayalakshmi, V.; Dhanasekaran, P.

2018-05-01

In the current work single crystals of pure and 1M of CuSO4-added glycine were grown by slow evaporation method and its optical and antimicrobial properties were studied. The Polymorph of glycine transforms from a-glycine to γ-glycine due to the incorporation of CuSO4 on glycine was affirmed by the PXRD and FTIR studies. The impact of CuSO4 on the antimicrobial action of the grown samples was deliberate by utilizing the agar diffusion method.

Thaumatin crystallization aboard the International Space Station using liquid-liquid diffusion in the Enhanced Gaseous Nitrogen Dewar (EGN).

PubMed

Barnes, Cindy L; Snell, Edward H; Kundrot, Craig E

2002-05-01

This paper reports results from the first biological crystal-growth experiment on the International Space Station (ISS). Crystals of thaumatin were grown using liquid-liquid diffusion in Tygon tubing transported in the Enhanced Gaseous Nitrogen Dewar (EGN). Different volume ratios and concentrations of protein and precipitant were used to test different adaptations of the vapor-diffusion crystallization recipe to the liquid-liquid diffusion method. The EGN warmed up from 77 to 273 K in about 4 d, about the same time it took to warm from 273 to 293 K. The temperature within the EGN was 293-297 K for the majority of the experiment. Air gaps that blocked liquid-liquid diffusion formed in the tubes. Nonetheless, crystals were grown. Synchrotron diffraction data collected from the best space-grown crystal extended to 1.28 A, comparable to previous studies of space-grown thaumatin crystals. The resolution of the best ground-control crystal was only 1.47 A. It is not clear if the difference in diffraction limit arises from factors other than crystal size. Improvements in temperature control and the elimination of air gaps are needed, but the results show that the EGN on the ISS can be used to produce space-grown crystals that diffract to high resolution.

Thaumatin Crystallization Aboard the International Space Station Using Liquid-Liquid Diffusion in the Enhanced Gaseous Nitrogen Dewar (EGN)

NASA Technical Reports Server (NTRS)

Kundrot, Craig; Barnes, Cindy L.; Snell, Edward H.; Stinson, Thomas N. (Technical Monitor)

2002-01-01

This paper reports results from the first biological crystal growth experiment on the International Space Station (ISS). Crystals of thaumatin were grown using liquid-liquid diffusion in Tygon tubing transported in the Enhanced Gaseous Nitrogen Dewar (EGN). Different Volume ratios and concentrations of protein and precipitant were used to test different adaptations of the vapor diffusion crystallization recipe to the liquid-liquid diffusion method. The EGN warmed up from -196 C to 0 C in about four days, about the same time it took to warm from 0 C to 20 C. The temperature within the EGN was 20 - 24 C for the majority of the experiment. Air gaps that blocked liquid-liquid diffusion formed in the tubes. Nonetheless, crystals were grown. Synchrotron diffraction data collected from the best space grown crystal extended to 1.28 Angstroms, comparable to previous studies of space-grown thaumatin crystals. The resolution of the best ground control crystal was only 1.47 Angstroms. It is not clear if the difference in diffraction limit is due to factors other than crystal size. Improvements in temperature control and the elimination of air gaps are needed, but the results show that EGN on the ISS can be used to produce space grown crystals that diffract to high resolution.

Crystal growth and characterization of semi-organic 2-amino-5-nitropyridinium bromide (2A5NPBr) single crystals for third-order nonlinear optical (NLO) applications

NASA Astrophysics Data System (ADS)

Vediyappan, Sivasubramani; Arumugam, Raja; Pichan, Karuppasamy; Kasthuri, Ramachandran; Muthu, Senthil Pandian; Perumal, Ramasamy

2017-12-01

Semi-organic nonlinear optical (NLO) 2-amino-5-nitropyridinium bromide (2A5NPBr) single crystals have been grown by slow evaporation solution technique (SEST) with the growth period of 60 days. The single-crystal XRD analysis confirms the unit cell parameters of the grown crystal. The crystallinity of grown 2A5NPBr was analyzed by powder X-ray diffraction (PXRD) measurement. The presence of functional groups of 2A5NPBr crystal was confirmed by Fourier transform infrared (FTIR) spectrum analysis. The optical transmittance of the grown crystal was analyzed by UV-Vis-NIR analysis. It shows good transparency in the visible and NIR region and it is favorable for nonlinear optical (NLO) device applications. The chemical etching study was carried out and it reveals that the grown crystal has less dislocation density. The photoconductivity study reveals that the grown crystal possesses positive photoconductive nature. The thermal stability of the crystal has been investigated by thermogravimetric (TG) and differential thermal analysis (DTA). The dielectric constant and dielectric loss as a function of frequency were measured. The electronic polarizability (α) of 2A5NPBr molecule has been calculated theoretically by different ways such as Penn analysis, Clausius-Mossotti relation, Lorentz-Lorenz equation, optical bandgap, and coupled dipole method (CDM). The obtained values of electronic polarizability (α) are in good agreement with each other. Laser damage threshold (LDT) of 2A5NPBr crystal has been measured using Nd:YAG laser with the wavelength of 1064 nm. Third-order nonlinear optical property of the grown crystal was studied by Z-scan technique using He-Ne laser of wavelength 632.8 nm.

Optical Properties of LiNbO3 Single Crystal Grown by Czochralski Method

NASA Astrophysics Data System (ADS)

Sahar, M. R.; Naim, N. M.; Hamzah, K.

2011-03-01

Pure LiNbO3 single crystal was grown by Czochralski method using Automatic Diameter Control—Crystal Growth System (ADC-CGS). The transmission spectrum was determined by using Infrared Spectroscopy while the refractive index was determined using UV-Vis spectroscopy via the Sellmeier equation. The density was also measured using the Archimedes principle. It was found that the peak for the absorption vibrational spectrum for LiNbO3 crystal occurs at 801 cm-1, 672 cm-1, 639 cm-1 and 435 cm-1. The refractive index, ne was found to be 2.480 and the crystal density was around 4.64 g/cm3.

Segregation control in vertical Bridgman crystal growth

NASA Astrophysics Data System (ADS)

Tao, Y.; Kou, S.

1996-11-01

To help the crystal grow at a constant dopant concentration in vertical Bridgman crystal growth, the dopant concentration of the growth melt, i.e. the melt from which the crystal grows, was kept constant. To achieve this, three different methods were used to replenish the growth melt at a controlled rate and suppress dopant diffusion between the growth melt and the replenishing melt. In method one, a replenishing crucible having a long melt passageway was immersed in the growth melt. In method two, a replenishing crucible having an independent feed-rate control mechanism was held above the growth melt. In method three, a submerged diffusion baffle was used to form a long melt passageway between the growth melt and the replenishing melt. NaNO 3 was used as a model material for crystal growth. Single crystals were grown by these three methods with effective segregation control. Method two was applied to InSb and single crystals were also grown with effective segregation control.

Thermoelectric properties of Ge 1-xSn xTe crystals grown by vertical Bridgman method

NASA Astrophysics Data System (ADS)

Wu, C. C.; Ferng, N. J.; Gau, H. J.

2007-06-01

Single crystals of Ge 1-xSn xTe compounds with x=0, 0.8, 0.9 and 1.0 were grown by vertical Bridgman method. The crystalline phase and stochiometry for these crystals were investigated by X-ray diffraction, metallographic microscope as well as electron-probe microanalysis (EPMA). Electrical property of the as-grown samples was characterized using room temperature resistivity and Hall measurements. The thermoelectric behaviors for the Ge 1-xSn xTe crystals were studied by means of thermal and carrier transport measurements. Temperature dependences of resistivity, Seebeck coefficient and thermal conductivity for the various compositions of Ge 1-xSn xTe were analyzed. A two-valence band model was proposed to describe the temperature dependence of thermoelectric property of the Ge 1-xSn xTe crystals. The dimensionless thermoelectric figure of merit ZT for the alloys was evaluated and discussed.

Microgravity

NASA Image and Video Library

2004-04-15

Comparison of Germanium Telluride (GeTe) Crystals grown on Earth (left) and in space (right) during the Skylab SL-3 mission. These crystals were grown using a vapor transport crystal growth method in the Multipurpose Electric Furnace System (MEFS). Crystals grown on earth are needles and platelettes with distorted surfaces and hollow growth habits. The length of the ground-based needle is approximately 2 mm and the average lenth of the platelets is 1 mm. The dull appearance of the Skylab crystals resulted from condensation of the transport agent during the long cooling period dictated by the Skylab furnace. In a dedicated process, this would be prevented by removing the ampoule from the furnace and quenching the vapor source.

Structural, thermal and optical properties of a semiorganic nonlinear optical single crystal: glycine zinc sulphate.

PubMed

Balakrishnan, T; Ramamurthi, K

2007-10-01

Glycine zinc sulphate salt was synthesized and the solubility and metastable zonewidth were estimated from the aqueous solution. Single crystals of glycine zinc sulphate were grown by solvent evaporation method from aqueous solution. Grown crystals were characterized by X-ray diffraction and FT-IR spectral analyses. The range and percentage of optical transmission was ascertained by recording UV-vis-NIR spectrum. Thermal properties of the crystal were investigated by thermogravimetric analysis. Microhardness study was carried out on (01-1) face of the grown crystal. Its powder second harmonic generation efficiency was measured using Nd:YAG laser and the value was observed to be 0.7 times that of potassium dihydrogen orthophosphate.

Optical parameters and dispersion behavior of potassium magnesium chloride sulfate single crystals doped with Co+2 ions

NASA Astrophysics Data System (ADS)

Abu El-Fadl, A.; Abd-Elsalam, A. M.

2018-05-01

Single crystals of potassium magnesium chloride sulfate (KMCS) doped with cobalt ions were grown by slow cooling method. Powder XRD study confirmed the monoclinic structure of the grown crystals. The functional group vibrations were checked through FTIR spectroscopy measurements. In optical studies, the absorbance behavior of the crystals and their optical energy gap were established by Tauc plot. The refractive index, the extinction coefficient and other optical constants were calculated for the grown crystals. The normal dispersion of the refractive index was analyzed according to single oscillator Sellmeier's model. The Urbach's rule was applied to analyze the localized states density in the forbidden gap.

Investigation of inorganic nonlinear optical potassium penta borate tetra hydrate (PPBTH) single crystals grown by slow evaporation method

NASA Astrophysics Data System (ADS)

Arivuselvi, R.; Babu, P. Ramesh

2018-03-01

Borates family crystals were plays vital role in the field of non linear optics (NLO) due to needs of wide range of applications. In this report, NLO crystals (potassium penta borate tetra hydrate (KB5H8O12) are grown by slow evaporation method at room temperature (28° C) and studied their physical properties. The harvested single crystals are transparent with the dimension of 12 × 10 × 6 mm3 and colourless. X-ray diffraction of single crystals reveals that the grown crystal belongs to orthorhombic system with non-centrosymmetric space group Pba2. All the absorbed functional groups are present in the order of inorganic compounds expect 1688 cm-1 because of water (Osbnd H sbnd O blending) molecule present in the pristine. Crystals show transparent in the entire visible region with 5.9 eV optical band gap and also it shows excellence in both second and third order nonlinear optical properties. Crystals can withstand upto 154 °C without any phase changes which is observed using thermal (TGA/DTA) analysis.

Nonstoichiometry and luminescent properties of ZnSe crystals grown from the melt at high pressures

NASA Astrophysics Data System (ADS)

Khanh, Tran; Mozhevitina, Elena; Khomyakov, Andrew; Avetisov, Roman; Davydov, Albert; Chegnov, Vladimir; Antonov, Vladimir; Kobeleva, Svetlana; Zhavoronkov, Nikolai; Avetissov, Igor

2017-01-01

50 mm diameter ZnSe crystals have been grown from the melt by a vertical Bridgman technique at 100 atm argon pressure in a graphite crucible. 3D impurities concentration and nonstoichiometry mappings of the grown crystals have been defined by ICP-MS and a direct physic-chemical method, correspondingly. Photoluminescence mapping of the analyzed crystal has been done. It was found out that along the crystal height the nonstoichiometry changed from Se excess over stoichiometrical composition in the cone (bottom) part to Zn excess in the tail (upper) part passing through the stoichiometrical composition in the cylindrical part of the crystal. Metal impurities concentrated in the upper part of the crystal. The gas-forming impurities (H, C, O, N, F) had stochastic distribution but Cl impurity concentrated in the crystal peripheral part (near the crucible walls). It was found out that the as-grown crystal had a single wide PL peal with maximum of 583 nm. A proposal about complex structure luminescent center based on Cl dopant an overstoichiometric Se has been made.

Crystal Growth of ZnSe and Related Ternary Compound Semiconductors by Vapor Transport in Low Gravity

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Ramachandran, N.

2013-01-01

Crystals of ZnSe and related ternary compounds, such as ZnSeS and ZnSeTe, will be grown by physical vapor transport in the Material Science Research Rack (MSRR) on International Space Station (ISS). The objective of the project is to determine the relative contributions of gravity-driven fluid flows to the compositional distribution, incorporation of impurities and defects, and deviation from stoichiometry observed in the crystals grown by vapor transport as results of buoyance-driven convection and growth interface fluctuations caused by irregular fluid-flows on Earth. The investigation consists of extensive ground-based experimental and theoretical research efforts and concurrent flight experimentation. The objectives of the ground-based studies are (1) obtain the experimental data and conduct the analyses required to define the optimum growth parameters for the flight experiments, (2) perfect various characterization techniques to establish the standard procedure for material characterization, (3) quantitatively establish the characteristics of the crystals grown on Earth as a basis for subsequent comparative evaluations of the crystals grown in a low-gravity environment and (4) develop theoretical and analytical methods required for such evaluations. ZnSe and related ternary compounds have been grown by vapor transport technique with real time in-situ non-invasive monitoring techniques. The grown crystals have been characterized extensively by various techniques to correlate the grown crystal properties with the growth conditions.

Growth and characterization of a novel nonlinear optical borate crystal - Yttrium calcium borate (YCB)

NASA Astrophysics Data System (ADS)

Arun Kumar, R.; Arivanandhan, M.; Dhanasekaran, R.; Hayakawa, Y.

2013-06-01

A new nonlinear optical single crystal yttrium calcium borate Y2CaB10O19 (YCB) was grown for the first time from its melt. The starting materials were prepared by the solid-state reaction method. The melting point of the synthesized material was identified to be 967 °C. YCB crystal exhibits monoclinic crystal structure with the space group C2. The crystalline perfection of the grown YCB crystal was found to be good. From the UV-VIS-NIR studies, the lower cutoff wavelength of the crystal occurs below 200 nm. The functional groups of the grown crystal were assigned using the FTIR data. The second harmonic generation (SHG) of the YCB crystal was observed using a Nd:YAG laser with a fundamental wavelength of 1064 nm. The laser damage threshold value of the YCB crystal was found to be very high - 10.5 GW/cm2.

Purification and Crystal Growth of Lead Iodide by Physical Vapor Transport Method

NASA Technical Reports Server (NTRS)

Wright, G. W.; Cole, M.; Chen, Y.-F.; Chen, K.-T.; Chen, H.; Chattopadhyay, K.; Burger, A.

1998-01-01

Lead iodide (PbI2) is a layered compound semiconductor being developed as room temperature x- and gamma-ray detector. Compared to the more studied material, mercuric iodide, PbI2 has a higher melting temperature and no phase transition until liquid phase which are indications of better mechanical properties. In this study, the source material was purified by the zone-refining process, and the purest section was extracted from center of the the zone-refined ingot to be grown by physical vapor transport (PVT) method. The zone-refined material and as-grown crystals were characterized by optical microscopy and differential scanning calorimetry (DSC) to reveal the surface morphology, purity and stoichiometry. The results shows that both materials are near-stoichiometric composition, with the purity of the as-grown crystals higher than zone-refined materials. The resistivity of the as-grown crystal (10" Omega-cm) was derived from current-voltage (I-V) measurement, and is 10 times higher than the zone-refined materials. Detail results will be presented and discussed.

Compositional segregation and electrical properties characterization of [001]- and [011]-oriented co-growth Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal

NASA Astrophysics Data System (ADS)

Song, Kexin; Li, Zhenrong; Guo, Haisheng; Xu, Zhuo; Fan, Shiji

2018-04-01

A Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 relaxor ferroelectric single crystal boule of 3 in. diameter was grown using [001]- and [011]-oriented co-growth crystals as seeds by the modified Bridgman method. The as-grown crystal boule was divided into two growth regions [001] and [011]. The composition and the electrical properties of samples of the two regions were characterized in detail along the growth direction in the whole crystal boule. The PT content of [001]-grown samples increased from 27.7 to 36.8 mol. % along the growth direction, especially they are averagely higher about 0.7 mol. % than those of [011]-grown samples at the same growth position. The PMN content of [001]-grown samples decreased from 43.0 to 34.8 mol. %, which is lower than that of the corresponding [011]-grown samples. The compositional segregation behavior along [001] and [011] growth directions was discussed based on the crystal growth theories. Variations in the rhombohedral to tetragonal phase transition temperature (TRT), the piezoelectric properties, the coercive electric field and the remnant polarization of [001] samples were discussed according to changes in compositional segregation and crystal anisotropy. Under the exact same growth conditions, the [011]-grown crystal has a larger composition segregation effect than that of the [001]-grown crystal. This result provides a positive effect on analysing the nature and reducing the effect of compositional segregation.

Recent results and new hardware developments for protein crystal growth in microactivity

NASA Technical Reports Server (NTRS)

Delucas, L. J.; Long, M. M.; Moore, K. M.; Smith, C.; Carson, M.; Narayana, S. V. L.; Carter, D.; Clark, A. D., Jr.; Nanni, R. G.; Ding, J.

1993-01-01

Protein crystal growth experiments have been performed on 16 space shuttle missions since April, 1985. The initial experiments utilized vapor diffusion crystallization techniques similar to those used in laboratories for earth-based experiments. More recent experiments have utilized temperature induced crystallization as an alternative method for growing high quality protein crystals in microgravity. Results from both vapor diffusion and temperature induced crystallization experiments indicate that proteins grown in microgravity may be larger, display more uniform morphologies, and yield diffraction data to significantly higher resolutions than the best crystals of these proteins grown on earth.

Melt growth of zinc aluminate spinel single crystal by the micro-pulling down method under atmospheric pressure

NASA Astrophysics Data System (ADS)

Kamada, K.; Shoji, Y.; Yamaji, A.; Kurosawa, S.; Yokota, Yuui; Ohashi, Y.; Kim, Kyoung Jin; Ivanov, M.; Kochurikhin, V. V.; Yoshikawa, A.

2018-06-01

ZnAl2O4 crystals were grown using few starting compositions with various ZnO:AlO3/2 ratio using an Ir wire seed and Ir + Re crucible under ordinary pressure with Ar + 2%O2 atmosphere by the radiofrequency heating μ-PD furnace. The ZnAl2O4 spinel single crystal with 4 mm diameter could be successfully grown by the μ-PD method by optimization of starting melt composition considering with Zinc oxide evaporation. During 10 min of growth under normal pressure the formation of ZnAl2O4 single phase observed even at high vapor pressure of ZnO. The transmittance spectra and X-ray locking curve were measured for evaluating of grown ZnAl2O4 crystals quality.

Models of Mass Transport During Microgravity Crystal Growth of Alloyed Semiconductors in a Magnetic Field

NASA Technical Reports Server (NTRS)

Ma, Nancy

2003-01-01

Alloyed semiconductor crystals, such as germanium-silicon (GeSi) and various II-VI alloyed crystals, are extremely important for optoelectronic devices. Currently, high-quality crystals of GeSi and of II-VI alloys can be grown by epitaxial processes, but the time required to grow a certain amount of single crystal is roughly 1,000 times longer than the time required for Bridgman growth from a melt. Recent rapid advances in optoelectronics have led to a great demand for more and larger crystals with fewer dislocations and other microdefects and with more uniform and controllable compositions. Currently, alloyed crystals grown by bulk methods have unacceptable levels of segregation in the composition of the crystal. Alloyed crystals are being grown by the Bridgman process in space in order to develop successful bulk-growth methods, with the hope that the technology will be equally successful on earth. Unfortunately some crystals grown in space still have unacceptable segregation, for example, due to residual accelerations. The application of a weak magnetic field during crystal growth in space may eliminate the undesirable segregation. Understanding and improving the bulk growth of alloyed semiconductors in microgravity is critically important. The purpose of this grant to to develop models of the unsteady species transport during the bulk growth of alloyed semiconductor crystals in the presence of a magnetic field in microgravity. The research supports experiments being conducted in the High Magnetic Field Solidification Facility at Marshall Space Flight Center (MSFC) and future experiments on the International Space Station.

Crystallization of Chicken Egg-White Lysozyme from Ammonium Sulfate

NASA Technical Reports Server (NTRS)

Forsythe, Elizabeth L.; Snell, Edward H.; Pusey, Marc L.

1997-01-01

Chicken egg-white lysozyme was crystallized from ammonium sulfate over the pH range 4.0-7.8, with protein concentrations from 100 to 150 mg/ml. Crystals were obtained by vapor-diffusion or batch-crystallization methods. The protein crystallized in two morphologies with an apparent morphology dependence on temperature and protein concentration. In general, tetragonal crystals could be grown by lowering the protein concentration or temperature. Increasing the temperature or protein concentration resulted in the growth of orthorhombic crystals. Representative crystals of each morphology were selected for X-ray analysis. The tetragonal crystals belonged to the P4(sub 3)2(sub 1)2 space group with crystals grown at ph 4.4 having unit-cell dimensions of a = b = 78.7 1, c=38.6 A and diffracting to beyond 2.0 A. The orthorhombic crystals, grown at pH 4.8, were of space group P2(sub 1)2(sub 1)2 and had unit-cell dimensions of a = 30.51, b = 56.51 and c = 73.62 A.

Synthesis aspects, structural, spectroscopic, antimicrobial and room temperature ferromagnetism of zinc iodide complex with Schiff based ligand.

PubMed

Shakila, K; Kalainathan, S

2015-01-25

In this paper, we report the successful growth of complex compound of zinc iodide with thiocarbamide by slow evaporation method. The single crystal XRD study reveals that the crystal belongs to monoclinic system with centrosymmetric space group and powder XRD analysis shows that the perfect crystalline nature of the crystal. The presence of functional group and element were confirmed from FT-IR and EDAX analysis. Optical absorbance of the grown crystal was studied by UV-Vis spectrophotometer. The optical constants were calculated from the optical absorbance data such as refractive index (n), extinction coefficient (K) and reflectance (R). The optical band gap (Eg) of thiocarbamide zinc iodide crystal is 4.22 eV. The magnetic properties of grown crystal have been determined by Vibrating Sample Magnetometry (VSM). Room temperature magnetization revealed a ferromagnetic behaviour for the grown crystal. The antibacterial and antifungal activities of the title compound were performed by well diffusion method and MIC method against the standard bacteria like Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and against fungus like Aspergillus niger, Rhizopus sps and Penicillium sps. Thermal behaviour of the crystal has been investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Copyright © 2014. Published by Elsevier B.V.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Zhe, E-mail: zhenzhe1201@sina.com; Yang, Lei; Hang, Yin

Highly transparent Dy{sup 3+}-doped terbium gallium garnet (TGG) single crystal was grown by Czochralski (Cz) method. Phase composition of the crystal was tested by XRD measurements. The distribution coefficient of Dy{sup 3+} in the crystal was obtained. The optical and magneto-optical properties were analyzed in detail, and magnetic properties of the Dy{sup 3+}-TGG crystal were studied. The paramagnetic behavior is observed down to 10 K. The as-grown crystal exhibited high optical transmittance, particularly in the visible region. The Faraday rotation was investigated over visible and near-infrared regions (VIS–NIR) at room temperature. The Verdet constants increase at measured wavelengths and highmore » thermal stability was found in Dy{sup 3+}-doped TGG, as compared to the properties of pure TGG, indicating that Dy{sup 3+}-doped crystals are preferable for magneto-active materials used in Faraday devices at VIS–NIR wavelengths. - Graphical abstract: Highly transparent Dy{sup 3+}-doped terbium gallium garnet (TGG) and pure TGG single crystals were grown by Czochralski method. The Dy{sup 3+}-doped TGG possesses 20–30% higher Verdet values in reference to TGG independently on wavelength.« less

Growth of high quality bulk size single crystals of inverted solubility lithium sulphate monohydrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silambarasan, A.; Rajesh, P., E-mail: rajeshp@ssn.edu.in; Ramasamy, P.

2015-06-24

The paper summarizes the processes of growing large lithium sulfate monohydrate (LSMH) single crystals. We have established a procedure to grow high quality bulk size single crystals of inverted solubility LSMH by a newly developed unidirectional crystallization technique called the Sankeranarayenan - Ramasamy (SR) method. The convective flow of crystal growth processes from solution and the conditions of growing crystals of various aspects were discussed. Good quality LSMH single crystal is grown of the size 20 mmX80 mm without cracks, localized-defects and inclusions. The as-grown crystals are suitable for piezoelectric and nonlinear optical applications.

Growth and characterization of pure and glycine doped cadmium thiourea sulphate (GCTS) crystals

NASA Astrophysics Data System (ADS)

Lawrence, M.; Thomas Joseph Prakash, J.

2012-06-01

The pure and glycine doped cadmium thiourea sulphate (GCTS) single crystals were grown successfully by slow evaporation method at room temperature. The concentration of dopant in the mother solution was 1 mol%. There is a change in unit cell. The Fourier transform infrared spectroscopy study confirms the incorporation of glycine into CTS crystal. The doped crystals are optically better and more transparent than the pure ones. The dopant increases the hardness value of the material. The grown crystals were also subjected to thermal and NLO studies.

Large scale crystallization of protein pharmaceuticals in microgravity via temperature change

NASA Technical Reports Server (NTRS)

Long, Marianna M.

1992-01-01

The major objective of this research effort is the temperature driven growth of protein crystals in large batches in the microgravity environment of space. Pharmaceutical houses are developing protein products for patient care, for example, human insulin, human growth hormone, interferons, and tissue plasminogen activator or TPA, the clot buster for heart attack victims. Except for insulin, these are very high value products; they are extremely potent in small quantities and have a great value per gram of material. It is feasible that microgravity crystallization can be a cost recoverable, economically sound final processing step in their manufacture. Large scale protein crystal growth in microgravity has significant advantages from the basic science and the applied science standpoints. Crystal growth can proceed unhindered due to lack of surface effects. Dynamic control is possible and relatively easy. The method has the potential to yield large quantities of pure crystalline product. Crystallization is a time honored procedure for purifying organic materials and microgravity crystallization could be the final step to remove trace impurities from high value protein pharmaceuticals. In addition, microgravity grown crystals could be the final formulation for those medicines that need to be administered in a timed release fashion. Long lasting insulin, insulin lente, is such a product. Also crystalline protein pharmaceuticals are more stable for long-term storage. Temperature, as the initiation step, has certain advantages. Again, dynamic control of the crystallization process is possible and easy. A temperature step is non-invasive and is the most subtle way to control protein solubility and therefore crystallization. Seeding is not necessary. Changes in protein and precipitant concentrations and pH are not necessary. Finally, this method represents a new way to crystallize proteins in space that takes advantage of the unique microgravity environment. The results from two flights showed that the hardware performed perfectly, many crystals were produced, and they were much larger than their ground grown controls. Morphometric analysis was done on over 4,000 crystals to establish crystal size, size distribution, and relative size. Space grown crystals were remarkably larger than their earth grown counterparts and crystal size was a function of PCF volume. That size distribution for the space grown crystals was a function of PCF volume may indicate that ultimate size was a function of temperature gradient. Since the insulin protein concentration was very low, 0.4 mg/ml, the size distribution could also be following the total amount of protein in each of the PCF's. X-ray analysis showed that the bigger space grown insulin crystals diffracted to higher resolution than their ground grown controls. When the data were normalized for size, they still indicated that the space crystals were better than the ground crystals.

Preliminary investigations of protein crystal growth using the Space Shuttle

NASA Technical Reports Server (NTRS)

Delucas, L. J.; Suddath, F. L.; Snyder, R.; Naumann, R.; Broom, M. B.; Pusey, M.; Yost, V.; Herren, B .; Carter, D.

1986-01-01

Four preliminary Shuttle experiments are described which have been used to develop prototype hardware for a more advanced system that will evaluate effects of gravity on protein crystal growth. The first phase of these experiments has centered on the development of micromethods for protein crystal growth by vapor-diffusion techniques (using a space version of the hanging-drop method) and on dialysis using microdialysis cells. Results suggest that the elimination of density-driven sedimentation can effect crystal morphology. In the dialysis experiment, space-grown crystals of concanavalin B were three times longer and 1/3 the thickness of earth-grown crystals.

Single crystal growth and characterization of kagomé-lattice shandites Co3Sn2-xInxS2

NASA Astrophysics Data System (ADS)

Kassem, Mohamed A.; Tabata, Yoshikazu; Waki, Takeshi; Nakamura, Hiroyuki

2015-09-01

Single crystals of the shandite-type half metallic ferromagnet Co3Sn2S2, and its In-substituted compounds, Co3Sn2-xInxS2 (0

Solid state parameters, structure elucidation, High Resolution X-Ray Diffraction (HRXRD), phase matching, thermal and impedance analysis on L-Proline trichloroacetate (L-PTCA) NLO single crystals.

PubMed

Kalaiselvi, P; Raj, S Alfred Cecil; Jagannathan, K; Vijayan, N; Bhagavannarayana, G; Kalainathan, S

2014-11-11

Nonlinear optical single crystal of L-Proline trichloroacetate (L-PTCA) was successfully grown by Slow Evaporation Solution Technique (SEST). The grown crystals were subjected to single crystal X-ray diffraction analysis to confirm the structure. From the single crystal XRD data, solid state parameters were determined for the grown crystal. The crystalline perfection has been evaluated using high resolution X-ray diffractometer. The frequencies of various functional groups were identified from FTIR spectral analysis. The percentage of transmittance was obtained from UV Visible spectral analysis. TGA-DSC measurements indicate the thermal stability of the crystal. The dielectric constant, dielectric loss and ac conductivity were measured by the impedance analyzer. The DC conductivity was calculated by the cole-cole plot method. Copyright © 2014 Elsevier B.V. All rights reserved.

Crystal-Physical Model of Ion Transport in Nonlinear Optical Crystals of KTiOPO4

NASA Astrophysics Data System (ADS)

Sorokin, N. I.; Shaldin, Yu. V.

2018-04-01

The ionic conductivity along the principal axes a, b, and c of the unit cell of the nonlinear-optical high-resistance KTiOPO4 single crystals (rhombic syngony, space group Pna21), which are as-grown and after thermal annealing in vacuum, has been investigated by the method of impedance spectroscopy. The crystals were grown from a solution-melt by the Czochralski method. The as-grown KTiOPO4 crystals possess a quasi-one-dimensional conductivity along the crystallographic c axis, which is caused by the migration of K+ cations: σ║ c = 1.0 × 10-5 S/cm at 573 K. Wherein the characteristics of the anisotropy of ionic conductivity of the crystals is equal to σ║ c /σ║ a = 3 and σ║ c /σ║ b = 24. The thermal annealing at 1000 K for 10 h in vacuum increases the magnitude of σ║ c of KTiOPO4 by a factor of 28 and leads to an increase in the ratio σ║ c /σ║ b = 2.1 × 103 at 573 K. A crystal-physical model of ionic transport in KTiOPO4 crystals has been proposed.

Investigations on synthesis, growth and physicochemical properties of semi-organic NLO crystal bis(thiourea) ammonium nitrate for nonlinear frequency conversion

NASA Astrophysics Data System (ADS)

Anbarasi, A.; Ravi Kumar, S. M.; Sundar, G. J. Shanmuga; Mosses, M. Allen; Raj, M. Packiya; Prabhakaran, M.; Ravisankar, R.; Gunaseelan, R.

2017-10-01

Bis(thiourea) ammonium nitrate (BTAN), a new nonlinear optical crystal was grown successfully by slow evaporation technique using water as solvent at room temperature. The grown crystals were optically good quality with dimensions upto 10 × 6 × 3 mm3. Single crystal X-Ray diffraction analysis reveals that the crystal lattice is orthorhombic. From Powder X-ray diffraction analysis the diffraction planes have been indexed. The presence of the various functional groups of BTAN was identified through FTIR spectroscopic analysis. UV cut-off wavelength was observed from optical absorbance spectrum and it was found to be 240 nm. Second harmonic efficiency was determined using Kurtz powder method in comparison with KDP to confirm the nonlinearity of the material. Thermal analysis confirmed that grown crystal is thermally stable upto 184 °C. Microhardness studies show that hardness number (Hv) increases with load. Conductivity measurements such as dielectric, ac and photoconductivity were studied. Growth mechanism and surface features of the as grown single crystal was analysed by chemical etching analysis.

Flight Experiments of Physical Vapor Transport of ZnSe: Growth of Crystals in Various Convective Conditions

NASA Technical Reports Server (NTRS)

Su, Ching-Hua

2015-01-01

A low gravity material experiment will be performed in the Material Science Research Rack (MSRR) on International Space Station (ISS). The flight experiment will conduct crystal growths of ZnSe and related ternary compounds, such as ZnSeS and ZnSeTe, by physical vapor transport (PVT). The main objective of the project is to determine the relative contributions of gravity-driven fluid flows to the compositional distribution, incorporation of impurities and defects, and deviation from stoichiometry observed in the grown crystals as results of buoyancy-driven convection and growth interface fluctuations caused by irregular fluid-flows on Earth. The investigation consists of extensive ground-based experimental and theoretical research efforts and concurrent flight experimentation. The objectives of the ground-based studies are (1) obtain the experimental data and conduct the analyses required to define the optimum growth parameters for the flight experiments, (2) perfect various characterization techniques to establish the standard procedure for material characterization, (3) quantitatively establish the characteristics of the crystals grown on Earth as a basis for subsequent comparative evaluations of the crystals grown in a low-gravity environment and (4) develop theoretical and analytical methods required for such evaluations. ZnSe and related ternary compounds have been grown by vapor transport technique with real time in-situ non-invasive monitoring techniques. The grown crystals have been characterized extensively by various techniques to correlate the grown crystal properties with the growth conditions. This talk will focus on the ground-based studies on the PVT crystal growth of ZnSe and related ternary compounds, especially the effects of different growth orientations related to gravity direction on the grown crystals.

SEMICONDUCTOR MATERIALS: Chemical etching of a GaSb crystal incorporated with Mn grown by the Bridgman method under microgravity conditions

NASA Astrophysics Data System (ADS)

Xiaofeng, Chen; Nuofu, Chen; Jinliang, Wu; Xiulan, Zhang; Chunlin, Chai; Yude, Yu

2009-08-01

A GaSb crystal incorporated with Mn has been grown by the Bridgman method on the Polizon facility onboard the FOTON-M3 spacecraft. Structural defects and growth striations have been successfully revealed by the chemical etching method. By calculating various parameters of the convection, the striation patterns can be explained, and the critical value of the Taylor number, which characterizes the convective condition of the rotating magnetic field induced azimuthal flow, was shown. The stresses generated during crystal growth can be reflected by the observations of etch pit distribution and other structural defects. Suggestions for improving the space experiment to improve the quality of the crystal are given.

Large piezoelectric properties in KNN-based lead-free single crystals grown by a seed-free solid-state crystal growth method

NASA Astrophysics Data System (ADS)

Yang, Jie; Zhang, Faqiang; Yang, Qunbao; Liu, Zhifu; Li, Yongxiang; Liu, Yun; Zhang, Qiming

2016-05-01

We report lead-free single crystals with a nominal formula of (K0.45Na0.55)0.96Li0.04NbO3 grown using a simple low-cost seed-free solid-state crystal growth method (SFSSCG). The crystals thus prepared can reach maximum dimensions of 6 mm × 5 mm × 2 mm and exhibit a large piezoelectric coefficient d33 of 689 pC/N. Moreover, the effective piezoelectric coefficient d33 * , obtained under a unipolar electric field of 30 kV/cm, can reach 967 pm/V. The large piezoelectric response plus the high Curie temperature (TC) of 432 °C indicate that SFSSCG is an effective approach to synthesize high-performance lead-free piezoelectric single crystals.

Effect of L-aspartic acid on the growth, structure and spectral studies of Zinc (tris) Thiourea Sulphate (ZTS) single crystals

NASA Astrophysics Data System (ADS)

Samuel, Bincy Susan; Krishnamurthy, R.; Rajasekaran, R.

2014-11-01

Single crystals of pure and L-aspartic acid doped Zinc (Tris) Thiourea Sulphate (ZTS) were grown from aqueous solution by solution growth method. The cell parameters and structure of the grown crystals were determined by X-ray diffraction studies. The presence of functional group in the compound has been confirmed by FTIR and FT-Raman analysis. The optical transparency range has been studied through UV-Vis spectroscopy. TGA/DTA studies show thermal stability of the grown crystals. Microhardness study reveals that the hardness number (Hv) increases with load for pure and doped ZTS crystals. Dielectric studies have been carried out and the results are discussed. The second harmonic generation was confirmed for L-aspartic acid doped ZTS which is greater than pure ZTS.

Spray printing of organic semiconducting single crystals

NASA Astrophysics Data System (ADS)

Rigas, Grigorios-Panagiotis; Payne, Marcia M.; Anthony, John E.; Horton, Peter N.; Castro, Fernando A.; Shkunov, Maxim

2016-11-01

Single-crystal semiconductors have been at the forefront of scientific interest for more than 70 years, serving as the backbone of electronic devices. Inorganic single crystals are typically grown from a melt using time-consuming and energy-intensive processes. Organic semiconductor single crystals, however, can be grown using solution-based methods at room temperature in air, opening up the possibility of large-scale production of inexpensive electronics targeting applications ranging from field-effect transistors and light-emitting diodes to medical X-ray detectors. Here we demonstrate a low-cost, scalable spray-printing process to fabricate high-quality organic single crystals, based on various semiconducting small molecules on virtually any substrate by combining the advantages of antisolvent crystallization and solution shearing. The crystals' size, shape and orientation are controlled by the sheer force generated by the spray droplets' impact onto the antisolvent's surface. This method demonstrates the feasibility of a spray-on single-crystal organic electronics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuz'micheva, G. M., E-mail: galkuz@mitht.ru; Zaharko, O.; Tyunina, E. A.

Langatate crystals of the general composition La{sub 3}(Ga{sub 0.5}Ta{sub 0.5})Ga{sub 5}O{sub 14}, grown by the Czochralski method, have been investigated by neutron diffraction (single crystals) and X-ray diffraction (ground single crystals). The crystals were grown in an atmosphere of 99% Ar + 1% O{sub 2} in the Y54{sup o} direction (rotation by 54{sup o} with respect to the y axis), without subsequent annealing (orange crystal) or with vacuum annealing (colorless crystal). It is established that colorless crystals have a higher gallium content and, therefore, a larger number of oxygen vacancies in comparison with colored crystals; this is a possible reasonmore » for their lower microhardness.« less

Macromolecular crystallization in microgravity generated by a superconducting magnet.

PubMed

Wakayama, N I; Yin, D C; Harata, K; Kiyoshi, T; Fujiwara, M; Tanimoto, Y

2006-09-01

About 30% of the protein crystals grown in space yield better X-ray diffraction data than the best crystals grown on the earth. The microgravity environments provided by the application of an upward magnetic force constitute excellent candidates for simulating the microgravity conditions in space. Here, we describe a method to control effective gravity and formation of protein crystals in various levels of effective gravity. Since 2002, the stable and long-time durable microgravity generated by a convenient type of superconducting magnet has been available for protein crystal growth. For the first time, protein crystals, orthorhombic lysozyme, were grown at microgravity on the earth, and it was proved that this microgravity improved the crystal quality effectively and reproducibly. The present method always accompanies a strong magnetic field, and the magnetic field itself seems to improve crystal quality. Microgravity is not always effective for improving crystal quality. When we applied this microgravity to the formation of cubic porcine insulin and tetragonal lysozyme crystals, we observed no dependence of effective gravity on crystal quality. Thus, this kind of test will be useful for selecting promising proteins prior to the space experiments. Finally, the microgravity generated by the magnet is compared with that in space, considering the cost, the quality of microgravity, experimental convenience, etc., and the future use of this microgravity for macromolecular crystal growth is discussed.

Synthesis, growth, structural, optical, spectral, thermal and mechanical studies of 4-methoxy 4-nitrostilbene (MONS): a new organic nonlinear optical single crystal.

PubMed

Dinakaran, Paul M; Bhagavannarayana, G; Kalainathan, S

2012-11-01

4-Methoxy 4-nitrostilbene (MONS), a new organic nonlinear optical material has been synthesized. Based on the solubility data good quality single crystal with dimensions up to 38×11×3 mm(3) has been grown by slow evaporation method using ethyl methyl ketone (MEK) as a solvent. Powder XRD confirms the crystalline property and also the diffraction planes have been indexed. The lattice parameters for the grown MONS crystals were determined by using single crystal X-ray diffraction analysis and it reveals that the crystal lattice system is triclinic. The crystalline perfection of the grown crystals has been analysed by high resolution X-ray diffraction (HRXRD) rocking curve measurements. Fourier transform infrared (FTIR) spectrum for powdered MONS sample confirms the functional groups present in the grown crystal. The UV-vis absorption spectrum has been recorded in the range of 190-1100 nm and the cut off wavelength 499 nm has been determined. The optical constants of MONS have been determined through UV-vis-NIR spectroscopy. The MONS crystals were further subjected to other characterizations. i.e., (1)H NMR, TG/DTA, photoluminescence and microhardness test. The Kurtz and Perry powder technique confirms the NLO property of the grown crystal and the SHG efficiency of MONS was found to be 1.55× greater than that of KDP crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

Method of fabricating low-dislocation-density epitaxially-grown films with textured surfaces

DOEpatents

Li, Qiming; Wang, George T

2015-01-13

A method for forming a surface-textured single-crystal film layer by growing the film atop a layer of microparticles on a substrate and subsequently selectively etching away the microparticles to release the surface-textured single-crystal film layer from the substrate. This method is applicable to a very wide variety of substrates and films. In some embodiments, the film is an epitaxial film that has been grown in crystallographic alignment with respect to a crystalline substrate.

Method for growth of crystals by pressure reduction of supercritical or subcritical solution

NASA Technical Reports Server (NTRS)

Shlichta, P. J. (Inventor)

1985-01-01

Crystals of high morphological quality are grown by dissolution of a substance to be grown into the crystal in a suitable solvent under high pressure, and by subsequent slow, time-controlled reduction of the pressure of the resulting solution. During the reduction of the pressure interchange of heat between the solution and the environment is minimized by performing the pressure reduction either under isothermal or adiabatic conditions.

Synthesis, growth and characterization of a nonlinear optical crystal: Bis l-proline hydrogen nitrate.

PubMed

Selvaraju, K; Kirubavathi, K

2013-11-01

The single crystals of bis l-proline hydrogen nitrate (BLPHN) belonging to non-centrosymmetric space group were successfully grown by the slow evaporation solution growth technique. The BLPHN crystals of size 10×7×3mm(3) were obtained in 35days. Initially, the solubility tests were carried out for two solvents such as deionized water and mixed of deionized water-acetone. Among the two solvents, the solubility of BLPHN was found to be the highest in deionized water, so crystallization of BLPHN was done from its aqueous solution. As grown, crystals were characterized by single crystal X-ray diffraction studies and optical transmission spectral studies. Infrared spectroscopy, thermo gravimetric analysis and differential thermal analysis measurements were performed to study the molecular vibration and thermal behavior of the grown BLPHN crystals. Nonlinear optical (NLO) behavior of BLPHN crystal was studied by Kurtz and Perry powder method. Copyright © 2013 Elsevier B.V. All rights reserved.

Convective Influence on Radial Segregation During Unidirectional Solidification of the Binary Alloy HgCdTe

NASA Technical Reports Server (NTRS)

Watring, D. A.; Gillies, D. C.; Lehoczky, S. L.; Szofran, F. R.; Alexander, H.

1996-01-01

In order to simulate the space environment for basic research into the crystal growth mechanism, Hg(0.8)Cd(0.2)Te crystals were grown by the vertical Bridgman-Stockbarger method in the presence of an applied axial magnetic field. The influence of convection, by magneto hydrodynamic damping, on mass transfer in the melt and segregation at the solid-liquid interface was investigated by measuring the axial and radial compositional variations in the grown samples. The reduction of convective mixing in the melt through the application of the magnetic field is found to have a large effect on radial segregation and interface morphology in the grown crystals. Direct comparisons are made with a Hg(0.8)Cd(0.2)Te crystal grown without field and also in the microgravity environment of space during the second United States Microgravity Payload Mission (USMP-2).

High nitrogen pressure solution growth of GaN

NASA Astrophysics Data System (ADS)

Bockowski, Michal

2014-10-01

Results of GaN growth from gallium solution under high nitrogen pressure are presented. Basic of the high nitrogen pressure solution (HNPS) growth method is described. A new approach of seeded growth, multi-feed seed (MFS) configuration, is demonstrated. The use of two kinds of seeds: free-standing hydride vapor phase epitaxy GaN (HVPE-GaN) obtained from metal organic chemical vapor deposition (MOCVD)-GaN/sapphire templates and free-standing HVPE-GaN obtained from the ammonothermally grown GaN crystals, is shown. Depending on the seeds’ structural quality, the differences in the structural properties of pressure grown material are demonstrated and analyzed. The role and influence of impurities, like oxygen and magnesium, on GaN crystals grown from gallium solution in the MFS configuration is presented. The properties of differently doped GaN crystals are discussed. An application of the pressure grown GaN crystals as substrates for electronic and optoelectronic devices is reported.

In situ study of the growth and degradation processes in tetragonal lysozyme crystals on a silicon substrate by high-resolution X-ray diffractometry

NASA Astrophysics Data System (ADS)

Kovalchuk, M. V.; Prosekov, P. A.; Marchenkova, M. A.; Blagov, A. E.; D'yakova, Yu. A.; Tereshchenko, E. Yu.; Pisarevskii, Yu. V.; Kondratev, O. A.

2014-09-01

The results of an in situ study of the growth of tetragonal lysozyme crystals by high-resolution X-ray diffractometry are considered. The crystals are grown by the sitting-drop method on crystalline silicon substrates of different types: both on smooth substrates and substrates with artificial surface-relief structures using graphoepitaxy. The crystals are grown in a special hermetically closed crystallization cell, which enables one to obtain images with an optical microscope and perform in situ X-ray diffraction studies in the course of crystal growth. Measurements for lysozyme crystals were carried out in different stages of the crystallization process, including crystal nucleation and growth, developed crystals, the degradation of the crystal structure, and complete destruction.

Synthesis, growth, structural, spectral, thermal, chemical etching, linear and nonlinear optical and mechanical studies of an organic single crystal 4-chloro 4-nitrostilbene (CONS): a potential NLO material.

PubMed

Dinakaran, Paul M; Kalainathan, S

2013-07-01

4-Chloro 4-nitrostilbene (CONS) a new organic nonlinear optical material has been synthesized. Employing slow evaporation method, good optical quality single crystals (dimensions up to 6×2×3 mm(3)) have been grown using ethyl methyl ketone (EMK) as a solvent. The grown crystals have been subjected to various characterizations such as single crystal X-ray diffraction, powder XRD, Fourier Transform Infrared spectroscopy (FTIR), proton NMR, solid UV absorption, SHG studies. Single crystal X-ray diffraction reveals that the crystal system belongs to monoclinic with noncentrosymmetric space group P21. The UV-Vis absorption spectrum has been recorded and found that the cut off wavelength is 380 nm. Functional groups and the structure of the title compound have been confirmed by FTIR and (1)H NMR spectroscopic analyses respectively. Molecular mass of the CONS confirmed by the high resolution mass spectral analysis .The thermal behavior of the grown crystal has been studied by TG/DTA analysis and it shows the melting point is at 188.66 °C. Dislocations and growth pattern present in the grown crystal revealed by the etching study. The mechanical strength of the CONS crystal has been studied by Vicker's hardness measurement. The SHG efficiency of the grown crystal has been determined by Kurtz and Perry powder test which revealed that the CONS crystal (327 mV) has 15 times greater efficiency than that of KDP (21.7 mV). Copyright © 2013 Elsevier B.V. All rights reserved.

Surrogate Seeds For Growth Of Crystals

NASA Technical Reports Server (NTRS)

Shlichta, Paul J.

1989-01-01

Larger crystals of higher quality grown. Alternative method for starting growth of crystal involves use of seed crystal of different material instead of same material as solution. Intended for growing single-crystal proteins for experiments but applicable in general to growth of crystals from solutions and to growth of semiconductor or other crystals from melts.

Unidirectional growth, rocking curve, linear and nonlinear optical properties of LPHCl single crystals

NASA Astrophysics Data System (ADS)

Kumar, P. Ramesh; Gunaseelan, R.; Raj, A. Antony; Selvakumar, S.; Sagayaraj, P.

2012-06-01

Nonlinear optical amino-acid single crystal of L-phenylalanine hydrochloride (LPHCl) was successfully grown by unidirectional Sankaranarayanan-Ramasamy (SR) method under ambient conditions for the first time. The grown single crystal was subjected to different characterization analyses in order to find out its suitability for device fabrication. The crystalline perfection was evaluated using high-resolution X-ray diffractometry. It is evident from the optical absorption study that crystal has excellent transmission in the entire visible region with its lower cut off wavelength around 290 nm.

Spectroscopic study of gel grown L-Valine Zinc Glycine Thiourea Sulfate (VZGTS) crystal: A novel NLO crystal

NASA Astrophysics Data System (ADS)

Rathod, Kiran T.; Patel, I. B.

2017-05-01

In recent years, organometalic non linear optical (NLO) materials have attained immense appeal form researchers due to its range of technological applications in photonic field and optoelectronic technology. In present research work, novel semi organic NLO L-Valine Zinc Glycine Thiourea Sulfate crystals (VZGTS) with different morphologies were grown by gel method at ambient temperature. Presence and identification of functional groups were confirmed by FITR analysis. Spectroscopic studies were carried out for it. The UV-Vis spectroscopy is recorded for crystal. PL study stats that the crystal has insulating nature. Spectroscopic study shows that this crystal has good transparency in the case of fundamental wavelength of Nd : YAG laser. Second Harmonic Generation (SHG) efficiency was confirmed by Kurtz - Perry powder method. Results are discussed in the paper.

Fast growth of n-type 4H-SiC bulk crystal by gas-source method

NASA Astrophysics Data System (ADS)

Hoshino, Norihiro; Kamata, Isaho; Tokuda, Yuichiro; Makino, Emi; Kanda, Takahiro; Sugiyama, Naohiro; Kuno, Hironari; Kojima, Jun; Tsuchida, Hidekazu

2017-11-01

Fast growth of n-type 4H-SiC crystals was attempted using a high-temperature gas-source method. High growth rates exceeding 9 mm/h were archived at a seed temperature of 2550 °C, although the formation of macro-step bunching caused doping fluctuation and voids in the grown crystal. We investigated a trade-off between growth-rate enhancement and macro-step formation and how to improve the trade-off. By controlling the growth conditions, the growth of highly nitrogen-doped 4H-SiC crystals without the doping fluctuation and void formation were accomplished under a high growth rate exceeding 3 mm/h, maintaining the density of threading screw dislocations in the same level with the seed crystal. The influence of growth parameters on nitrogen incorporations into grown crystals was also surveyed.

Growth and characterizaion of urea p-nitrophenol crystal: an organic nonlinear optical material for optoelectronic device application

NASA Astrophysics Data System (ADS)

Suresh, A.; Manikandan, N.; Jauhar, RO. MU.; Murugakoothan, P.; Vinitha, G.

2018-06-01

Urea p-nitrophenol, an organic nonlinear optical crystal was synthesized and grown adopting slow evaporation and seed rotation method. Single crystal X-ray diffraction study confirmed the formation of the desired crystal. High resolution X-ray diffraction study showed the defect nature of the crystal. The presence of functional groups in the material was confirmed by FTIR analysis. UV-Vis-NIR study indicates that the grown crystal has a wider transparency region with the lower cutoff wavelength at 423 nm. The grown crystal is thermally stable up to 120 °C as assessed by TG-DTA analysis. The optical homogeneity of the grown crystal was confirmed by birefringence study. The 1064 nm Nd-YAG laser was used to obtain laser induced surface damage threshold which was found to be 0.38, 0.25 and 0.33 GW/cm2 for (0 1 0), (1 1 - 1) and (0 1 1) planes, respectively. The dielectric study was performed to find the charge distribution inside the crystal. The hardness property of the titular material has been found using Vicker's microhardness study. The optical nonlinearity obtained from third order nonlinear optical measurements carried out using Z-scan technique showed that these samples could be exploited for optical limiting studies.

A novel structure of gel grown strontium cyanurate crystal and its structural, optical, electrical characterization

NASA Astrophysics Data System (ADS)

Divya, R.; Nair, Lekshmi P.; Bijini, B. R.; Nair, C. M. K.; Gopakumar, N.; Babu, K. Rajendra

2017-12-01

Strontium cyanurate crystals with novel structure and unique optical property like mechanoluminescence have been grown by conventional gel method. Transparent crystals were obtained. The single crystal X-ray diffraction analysis reveals the exquisite structure of the grown crystal. The crystal is centrosymmetric and has a three dimensional polymeric structure. The powder X ray diffraction analysis confirms its crystalline nature. The functional groups present in the crystal were identified by Fourier transform infrared spectroscopy. Elemental analysis confirmed the composition of the complex. A study of thermal properties was done by thermo gravimetric analysis and differential thermal analysis. The optical properties like band gap, refractive index and extinction coefficient were evaluated from the UV visible spectral analysis. The etching study was done to reveal the dislocations in the crystal which in turn explains mechanoluminescence emission. The mechanoluminescence property exhibited by the crystal makes it suitable for stress sensing applications. Besides being a centrosymmetric crystal, it also exhibits NLO behavior. Dielectric properties were studied and theoretical calculations of Fermi energy, valence electron plasma energy, penn gap and polarisability have been done.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, Piyush, E-mail: piyush-patel130@yahoo.com; Vyas, S. M., E-mail: s-m-vyas-gu@hotmail.com; Patel, Vimal

The III-VI compound semiconductors is important for the fabrication of ionizing radiation detectors, solid-state electrodes, and photosensitive heterostructures, solar cell and ionic batteries. In this paper, In{sub 2}Se{sub 2.7} Sb{sub 0.3} single crystals were grown by the Bridgman method with temperature gradient of 60 °C/cm and the growth velocity 0.5cm/hr. The as-grown crystals were examined under the optical microscope for surface study, a various growth features observed on top free surface of the single crystal which is predominant of layers growth mechanism. The lattice parameters of as-grown crystal was determined by the XRD analysis. A Vickers’ projection microscope were usedmore » for the study of microhardness on the as-cleaved, cold-worked and annealed samples of the crystals, the results were discussed, and reported in detail.« less

Synthesis of sub-millimeter calcite from aqueous solution

NASA Astrophysics Data System (ADS)

Reimi, M. A.; Morrison, J. M.; Burns, P. C.

2011-12-01

A novel aqueous synthesis that leads to the formation of calcite (CaCO3) crystals, up to 500μm in diameter, will be used to facilitate the study of contaminant transport in aqueous environmental systems. Existing processes tend to be complicated and often yield nanometer-sized or amorphous CaCO3. The synthesis method presented here, which involves slow mixing of concentrated solutions of CaCl2 ¬and (NH4)2CO3, produces single crystals of rhombohedral calcite in 2 to 4 days. Variations on the experimental method, including changes in pH and solution concentration, were explored to optimize the synthesis. Scanning Electron Microscope images show the differences in size and purity observed when the crystals are grown at pH values ranging from 2 to 6. The crystals grown from solutions of pH 2 were large (up to 500 micrometers in diameter) with minimal polycrystalline calcium carbonate, while crystals grown from solutions with pH values beyond 4 were smaller (up to 100 micrometers in diameter) with significant polycrystalline calcium carbonate. The synthesis method, materials characterization, and use in future actinide contaminant studies will be discussed.

Dewetting During the Crystal Growth of (Cd,Zn)Te:In Under Microgravity

NASA Astrophysics Data System (ADS)

Sylla, Lamine; Fauler, Alex; Fiederle, Michael; Duffar, Thierry; Dieguez, Ernesto; Zanotti, Lucio; Zappettini, Andrea; Roosen, GÉrald

2009-08-01

The phenomenon of ldquodewettingrdquo associated with the Vertical Bridgman (VB) crystal growth technique leads to the growth of a crystal without contact with the crucible. One dramatic consequence of this modified VB process is the reduction of structural defects within the crystal. It has been observed in several microgravity experiments for different semiconductor crystals. This work is concentrated on the growth of high resistivity (Cd,Zn)Te:In (CZT) crystals by achieving the phenomenon of dewetting under microgravity condition and its application in the processing of CZT detectors. Two Cd0.9Zn0.1Te:In crystals were grown in space on the Russian FOTON satellite in the POLIZON-M facility in September 2007 (mission M3). At the end of the preliminary melting phase of one crystal, a Rotating Magnetic Field (RMF) was applied in order to reduce the typical tellurium clusters within the melt before the pulling. The other crystal was superheated with 20 K above the melting point before the pulling. A third reference crystal has been grown on the ground in similar thermal conditions. Profiles measurements of the space grown crystals surface gave the evidence of a successful dewetting during the crystal growth. Characterization methods such as IR microscopy and CoReMa have been performed on the three crystals. CZT detectors have been processed from the grown part of the different crystals. The influence of the dewetting on the material quality and the detector properties completes the study.

Growth and characterization of pure and Cadmium chloride doped KDP Crystals grown by gel medium

NASA Astrophysics Data System (ADS)

Kalaivani, M. S.; Asaithambi, T.

2016-10-01

Crystal growth technology provides an important basis for many industrial branches. Crystals are the unrecognized pillars of modern technology. Without crystals, there is no electronic industry, no photonic industry, and no fiber optic communications. Single crystals play a major role and form the strongest base for the fast growing field of engineering, science and technology. Crystal growth is an interdisciplinary subject covering physics, chemistry, material science, chemical engineering, metallurgy, crystallography, mineralogy, etc. In past few decades, there has been a keen interest on crystal growth processes, particularly in view of the increasing demand of materials for technological applications. Optically good quality pure and metal doped KDP crystals have been grown by gel method at room temperature and their characterization have been studied. Gel method is a much uncomplicated method and can be utilized to synthesize crystals which are having low solubility. Potassium dihydrogen orthophosphate KH2PO4 (KDP) continues to be an interesting material both academically and industrially. KDP is a representative of hydrogen bonded materials which possess very good electro - optic and nonlinear optical properties in addition to interesting electrical properties. Due to this interesting properties, we made an attempt to grow pure and cadmium chloride doped KDP crystals in various concentrations (0.002, 0.004, 0.006, 0.008 and 0.010) using gel method. The grown crystals were collected after 20 days. We get crystals with good quality and shaped. The dc electrical conductivity (resistance, capacitance and dielectric constant) values were measured at frequencies in the range of 1 KHZ and 100 HZ of pure and cadmium chloride added crystal with a temperature range of 400C to 1300C using simple two probe setup with Q band digital LCR meter present in our lab. The electrical conductivity increases with increase of temperature. The dielectric constants of metal doped KDP crystals were slightly decreased compared to pure KDP crystals.

Extremely large magnetoresistance in a high-quality WTe2 grown by flux method

NASA Astrophysics Data System (ADS)

Tsumura, K.; Yano, R.; Kashiwaya, H.; Koyanagi, M.; Masubuchi, S.; Machida, T.; Namiki, H.; Sasagawa, T.; Kashiwaya, S.

2018-03-01

We have grown single crystals of WTe2 by a self-flux method and evaluated the quality of the crystals. A Hall bar-type device was fabricated from an as-exfoliated film on a Si substrate and longitudinal resistance Rxx was measured. Rxx increased with an applied perpendicular magnetic field without saturation and an extremely large magnetoresistance as high as 376,059 % was observed at 8.27 T and 1.7 K.

Growth, spectral, thermal, dielectric, mechanical, linear and nonlinear optical, birefringence, laser damage threshold studies of semi-organic crystal: dibrucinium sulfate heptahydrate.

PubMed

Krishnan, P; Gayathri, K; Bhagavannarayana, G; Jayaramakrishnan, V; Gunasekaran, S; Anbalagan, G

2013-08-01

Dibrucinium sulfate heptahydrate (DBSH), a semi-organic nonlinear optical material, has been synthesized and single crystals were grown from water-ethanol solution at room temperature up to dimensions of 10×7×2 mm(3). The unit cell parameters were determined from single crystal and powder X-ray diffraction studies. The structural perfection of the grown crystal has been analyzed by high-resolution X-ray diffraction (HRXRD) study. FTIR and Raman studies were performed to identify the functional groups present in the title compound. The activation energy (E), entropy (ΔS), enthalpy (ΔH) and Gibbs free energy (ΔG), of the thermal decomposition reaction have been derived from thermo gravimetric (TGA) and differential thermal (DTA) analysis curves, using Coats-Redfern method. The variation of dielectric properties of the grown crystal with respect to frequency has been investigated at different temperatures. Microhardness measurements revealed the mechanical strength of grown crystal. The optical parameters, the optical band gap E(g) and width of localized states Eu were determined using the transmittance data in the spectral range 200-800 nm. The relative second harmonic efficiency of the compound is found to be 1.4 times greater than that of KDP. Birefringence and Laser damage threshold studies were carried out for the grown crystal. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis, crystal growth, optical, thermal, and mechanical properties of a nonlinear optical single crystal: ammonium sulfate hydrogen sulphamate (ASHS)

NASA Astrophysics Data System (ADS)

Sudhakar, K.; Nandhini, S.; Muniyappan, S.; Arumanayagam, T.; Vivek, P.; Murugakoothan, P.

2018-04-01

Ammonium sulfate hydrogen sulphamate (ASHS), an inorganic nonlinear optical crystal, was grown from the aqueous solution by slow evaporation solution growth technique. The single-crystal XRD confirms that the grown single crystal belongs to the orthorhombic system with the space group of Pna21. Powder XRD confirms the crystalline nature and the diffraction planes were indexed. Crystalline perfection of grown crystal was analysed by high-resolution X-ray diffraction rocking curve technique. UV-Vis-NIR studies revealed that ASHS crystal has optical transparency 65% and lower cut-off wavelength at 218 nm. The violet light emission of the crystal was identified by photoluminescence studies. The particle size-dependent second-harmonic generation efficiency for ASHS crystal was evaluated by Kurtz-Perry powder technique using Nd:YAG laser which established the existence of phase matching. Surface laser damage threshold value was evaluated using Nd:YAG laser. Optical homogeneity of the crystal was evaluated using modified channel spectrum method through birefringence study. Thermal analysis reveals that ASHS crystal is stable up to 213 °C. The mechanical behaviour of the ASHS crystal was analysed using Vickers microhardness study.

Kinetics of the current response in TlBr detectors under a high dose rate of {gamma}-ray irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gazizov, I. M., E-mail: gazizov@isotop.dubna.ru; Zaletin, V. M.; Kukushkin, V. M.

2012-03-15

The kinetics of the photocurrent response in doped and undoped TlBr samples subjected to irradiation with {gamma}-ray photons from a {sup 137}Cs source with the dose rate 0.033 to 3.84 Gy/min are studied. The crystals were grown by the directional crystallization of the melt method using the Bridgman-Stockbarger technique. The Pb impurity mass fraction introduced into the doped TlBr crystals was 1-10 ppm and amounted to 150 ppm for the Ca impurity. The crystals were grown in a vacuum, in bromine vapors, in a hydrogen atmosphere, and in air. Decay of the photocurrent is observed for extrinsic semiconductor crystals dopedmore » with bivalent cations (irrespective of the growth atmosphere), and also for crystals grown in hydrogen and crystals grown in an excess of thallium. The time constant of photocurrent decay {tau} amounted to 30-1400 s and was proportional to resistivity. It is shown that the current response can be related to photolysis in the TlBr crystals during irradiation with {gamma}-ray photons. The energy of hole traps responsible for a slow increase in the photo-current has been estimated and found to be equal to 0.6-0.85 eV.« less

Growth experiment of narrow band-gap semiconductor PbSnTe single crystals in space (M-1)

NASA Technical Reports Server (NTRS)

Yamada, Tomoaki

1993-01-01

An experiment on crystal growth of Pb(1-x)Sn(x)Te in microgravity is planned. This material is an alloy of the compound semiconductors PbTe and SnTe. It is a promising material for infrared diode lasers and detectors in the wavelength region between 6 and 30 micron. Since the electrical properties of Pb(1-x)Sn(x)Te depend greatly on the Pb/Sn ratio and crystalline defects as well as impurity concentration, homogeneous, defect-free, high-quality crystals are anticipated. Although many growth methods, such as the pulling method, the Bridgman method, the vapor growth method, etc., have been applied to the growth of Pb(1-x)Sn(x)Te, large, homogeneous, low-defect-density crystals have not yet been grown on Earth. The unsuccessful results were caused by buoyancy-driven convection in the fluids induced by the specific gravity difference between heated and cooled fluids on Earth. A crystal is grown by cooling the melt from one end of the ampoule. In crystal growth from the melt, about 30 percent of the SnTe in the melt is rejected at the solid-liquid interface during solidification. On Earth, the rejected SnTe is completely mixed with the remaining melt by convection in the melt. Therefore, SnTe concentration in the melt, and accordingly in the crystal, increases as the crystal grows. In the microgravity environment, buoyancy-driven convection is suppressed because the specific gravity difference is negligible. In that case, the rejected SnTe remains at the solid-liquid interface and its concentration increases only at the interface. If the growth rate is higher than the PbTe-SnTe interdiffusion rate, the amount of SnTe which diffuses from the interface into the melt increases as SnTe piles up at the interface, and finally it balances the amount of rejected SnTe during solidification, resulting in steady-state SnTe transportation at the interface. By using this principle, compositionally homogeneous crystals can be grown. Furthermore, low-defect-density crystals will be grown in microgravity, because convection causes crystalline defects by mising hot and cold fluids and generating temperature fluctuations in them.

Crystal growth and characterization of Ce:Gd3(Ga,Al)5O12 single crystal using floating zone method in different O2 partial pressure

NASA Astrophysics Data System (ADS)

Yoshikawa, Akira; Fujimoto, Yutaka; Yamaji, Akihiro; Kurosawa, Shunsuke; Pejchal, Jan; Sugiyama, Makoto; Wakahara, Shingo; Futami, Yoshisuke; Yokota, Yuui; Kamada, Kei; Yubuta, Kunio; Shishido, Toetsu; Nikl, Martin

2013-09-01

Multicomponent garnet Ce:Gd3(Ga,Al)5O12 (Ce:GAGG) single crystals show very high light yield with reasonably fast scintillation response. Therefore, they can be promising scintillators for gamma-ray detection. However, in the decay curve a very slow component does exist. Therefore, it is necessary to optimize further the crystal growth technology of Ce:GAGG. In this study, Ce:GAGG single crystals were grown by the floating zone (FZ) method under atmospheres of various compositions such as Ar 100%, Ar 80% + O2 20%, Ar 60% + O2 40% and O2 100%. Radioluminescence spectra are dominated by the band at about 540 nm due to Ce3+ 5d1-4f transition. The Ce:GAGG single crystal grown under Ar atmosphere shows an intense slower decay component. It can be related to the processes of the delayed radiative recombination and thermally induced ionization of 5d1 level of Ce3+ center possibly further affected by oxygen vacancies. This slower decay process is significantly suppressed in the samples grown under the O2 containing atmosphere.

Photoluminescence of vapor and solution grown ZnTe single crystals

NASA Astrophysics Data System (ADS)

Biao, Y.; Azoulay, M.; George, M. A.; Burger, A.; Collins, W. E.; Silberman, E.; Su, C.-H.; Volz, M. E.; Szofran, F. R.; Gillies, D. C.

1994-04-01

ZnTe single crystals grown by horizontal physical vapor transport (PVT) and by vertical traveling heater method (THM) from a Te solution were characterized by photoluminescence (PL) at 10.6 K and by atomic force microscopy (AFM). Copper was identified by PL as a major impurity existing in both crystals, forming a substitutional acceptor, Cu Zn. The THM ZnTe crystals were found to contain more Cu impurity than the PVT ZnTe crystals. The formation of Cu Zn-V Te complexes and the effects of annealing, oxygen contamination and intentional Cu doping were also studied. Finally, the surface morphology analyzed by AFM was correlated to the PL results.

Crystal growth of HVPE-GaN doped with germanium

NASA Astrophysics Data System (ADS)

Iwinska, M.; Takekawa, N.; Ivanov, V. Yu.; Amilusik, M.; Kruszewski, P.; Piotrzkowski, R.; Litwin-Staszewska, E.; Lucznik, B.; Fijalkowski, M.; Sochacki, T.; Teisseyre, H.; Murakami, H.; Bockowski, M.

2017-12-01

Crystallization by hydride vapor phase epitaxy method of gallium nitride single crystals doped with germanium and properties of the obtained material are described in this paper. Growth was performed in hydrogen and nitrogen carrier gas. The results were studied and compared. Influence of different flows of germanium tetrachloride, precursor of germanium, on the grown crystals was investigated. Ammonothermal GaN substrates were used as seeds for crystallization. Structural, electrical, and optical properties of HVPE-GaN doped with germanium are presented and discussed in detail. They were compared to properties of HVPE-GaN doped with silicon and also grown on native seeds of high quality.

Gallium arsenide single crystal solar cell structure and method of making

NASA Technical Reports Server (NTRS)

Stirn, Richard J. (Inventor)

1983-01-01

A production method and structure for a thin-film GaAs crystal for a solar cell on a single-crystal silicon substrate (10) comprising the steps of growing a single-crystal interlayer (12) of material having a closer match in lattice and thermal expansion with single-crystal GaAs than the single-crystal silicon of the substrate, and epitaxially growing a single-crystal film (14) on the interlayer. The material of the interlayer may be germanium or graded germanium-silicon alloy, with low germanium content at the silicon substrate interface, and high germanium content at the upper surface. The surface of the interface layer (12) is annealed for recrystallization by a pulsed beam of energy (laser or electron) prior to growing the interlayer. The solar cell structure may be grown as a single-crystal n.sup.+ /p shallow homojunction film or as a p/n or n/p junction film. A Ga(Al)AS heteroface film may be grown over the GaAs film.

Growth of a decagonal Al 70Ni 15Co 15 single quasicrystal by the Czochralski method

NASA Astrophysics Data System (ADS)

Jeong, H. T.; Kim, S. H.; Kim, W. T.; Kim, D. H.; Inkson, B. J.

2000-07-01

Single decagonal quasicrystals of Al 70Ni 15Co 15 were grown by the Czochralski method at Ar atmosphere. The grown crystals were of single decagonal phase without any secondary phases due to the peritectic reaction and contained a large single quasicrystal of cm order size. The high quality and single quasicrystallinity of them were examined by the Laue transmission photography, single crystal X-ray diffraction, and high-resolution electron microscopy investigations.

Crystal Growth of Ternary Compound Semiconductors in Low Gravity Environment

NASA Technical Reports Server (NTRS)

Su, Ching-Hua

2014-01-01

A low gravity material experiment will be performed in the Material Science Research Rack (MSRR) on International Space Station (ISS). There are two sections of the flight experiment: (I) crystal growth of ZnSe and related ternary compounds, such as ZnSeS and ZnSeTe, by physical vapor transport (PVT) and (II) melt growth of CdZnTe by directional solidification. The main objective of the project is to determine the relative contributions of gravity-driven fluid flows to the compositional distribution, incorporation of impurities and defects, and deviation from stoichiometry observed in the grown crystals as results of buoyancy-driven convection and growth interface fluctuations caused by irregular fluid-flows on Earth. The investigation consists of extensive ground-based experimental and theoretical research efforts and concurrent flight experimentation. This talk will focus on the ground-based studies on the PVT crystal growth of ZnSe and related ternary compounds. The objectives of the ground-based studies are (1) obtain the experimental data and conduct the analyses required to define the optimum growth parameters for the flight experiments, (2) perfect various characterization techniques to establish the standard procedure for material characterization, (3) quantitatively establish the characteristics of the crystals grown on Earth as a basis for subsequent comparative evaluations of the crystals grown in a low-gravity environment and (4) develop theoretical and analytical methods required for such evaluations. ZnSe and related ternary compounds have been grown by vapor transport technique with real time in-situ non-invasive monitoring techniques. The grown crystals have been characterized extensively by various techniques to correlate the grown crystal properties with the growth conditions.

Solution Growth of a Novel Nonlinear Optical Material: L-Histidine Tetrafluoroborate

NASA Technical Reports Server (NTRS)

Aggarwal, M. D.; Choi, J.; Wang, W. S.; Bhat, K.; Lal, R. B.; Shields, Angela D.; Penn, Benjamin G.; Frazier, Donald O.

1998-01-01

Single crystals of L-Histidine tetrafluoroborate (L-HFB), a semiorganic nonlinear optical (NLO) material have been successfully grown by the temperature lowering and evaporation methods in our laboratory. Solubility curves of L-HFB have been determined in different solvents, such as water, ethanol and acetone. The solubility of L-HFB is very low in acetone, and ethanol, therefore, it is not feasible to grow L-HFB single crystals using these solvents. Good quality single crystals of a novel nonlinear optical material L-HFB have been grown from aqueous solution. Effects of seed orientation on morphologies of L-HFB crystals were studied. The advantages and disadvantage of both the evaporation and the temperature lowering techniques are compared. The single crystals in size 20 x 20 x 10 cubic mm were grown with deionized water as solvent in two weeks with an approximate growth rate of 1.4mm/day. The transmission range for these crystals has been found to be from 250 nm to 1500 nm.

Structural and optical properties of indium-doped highly conductive ZnO bulk crystals grown by the hydrothermal technique

NASA Astrophysics Data System (ADS)

Wang, Buguo; Claflin, Bruce; Look, David; Jiménez, Juan

2018-02-01

Indium-doped ZnO bulk crystals grown by the hydrothermal method are highly-conductive, with resistivity at 0.01 Ωcm at room temperature as revealed by Hall-effect measurement. In this paper we report on structural and optical properties of these crystals. The grown In:ZnO crystals have been studied by high resolution X-ray diffraction, micro-Raman scattering and low-temperature photoluminescence and cathodoluminescence. It was found that the c lattice parameter of the grown In:ZnO crystal expanded 0.06% with respect to the lithium-doped ZnO crystal seed, and the In-doped ZnO overgrew the seed crystal pseudomorphically but with high quality crystallinity; the X-ray rocking curves show the FWHM of the Zn face and O faces are only 0.05° and 0.1° ; and the indium concentration in the crystal reaches the solubility limit. Raman spectra show strain relaxation gradually from the regrowth interface as well as a weak spectral feature at 723 cm-1. The peak at 312 cm-1 noticed in hydrothermally grown In:ZnO nanostructures does not appear in our In-doped crystals, indicating that this peak may be associated with specific defects (e.g. surface related) of the nanostructures. Photoluminescence measurements show that an indium donor bound exciton peak I9 (In0X) is the dominant peak in the PL spectrum, located at 3.3586 eV on the zinc face and 3.3577 eV on the oxygen face. Both of them deviated from the consensus literature value of 3.3567 eV, probably due to strain in the crystal induced by impurities.

Growth of urea crystals by physical vapor transport

NASA Technical Reports Server (NTRS)

Feigelson, R. S.; Route, R. K.; Kao, T.-M.

1985-01-01

This work demonstrates that high optical quality crystals of urea can be grown by the physical vapor transport method. The unique features of this method are compared with growth from methanol/water solutions. High growth rates, exceeding 2.5 mm/day, were achieved, and cm-size optical quality single crystals were obtained. Details of the growth technique and the physical properties of the crystals are presented.

The composition effect on the thermal and optical properties across CdZnTe crystals

NASA Astrophysics Data System (ADS)

Strzałkowski, K.

2016-11-01

Cd1-x Zn x Te mixed crystals investigated in this work were grown from the melt using the vertical Bridgman-Stockbarger method in the whole range of composition 0  <  x  <  1 that is from one binary crystal (CdTe) to another (ZnTe). The real composition of grown crystals was measured with the SEM/EDS method along the growth axis. The segregation coefficient of Zn in a CdTe matrix has been evaluated as being close to unity. The energy gap as a function of the composition was determined from transmission spectroscopy. Thanks to that, the bowing parameter of this ternary alloy was found to be 0.458. In this work the systematical study of thermal properties of Cd1-x Zn x Te alloys from one binary crystal (CdTe) to another (ZnTe) grown by the vertical Bridgman technique were undertaken for the first time. The thermal diffusivity and effusivity of the investigated crystals were derived from the experimental data and allowed the thermal conductivity to be calculated. Diagrams of the thermal conductivity versus composition were analyzed applying the model for mixed semiconducting crystals given by Sadao Adachi. Thanks to that, the contribution of the thermal resistivity arising from the lattice disorder to the total resistivity of the crystal has been determined.

Dipicolinate salt of imidazole: Discovering its structure and properties using different experimental methodologies and quantum chemical investigations

NASA Astrophysics Data System (ADS)

Thirumurugan, R.; Anitha, K.

2018-03-01

A novel organic proton transfer complex of imidazolium dipicolinate (ID) has been synthesized and it was grown as single crystals using slow evaporation method. The molecular structure of synthesized compound and vibrational modes of its functional groups were confirmed by (1H and 13C) NMR, FTIR and FT-Raman spectroscopic studies, respectively. Single crystal X-ray diffraction (SCXRD) analysis confirmed the orthorhombic system with noncentrosymmetric (NCS), P212121, space group of grown ID crystal. UV-Vis-NIR spectral study confirmed its high optical transparency within the region of 285-1500 nm. Powder second harmonic generation (SHG) efficiency of ID crystal was confirmed and it was 6.8 times that of KDP crystal. TG-DTA and DSC analysis revealed the higher thermal stability of grown crystal as 249 °C. The dielectric response and mechanical behaviour of grown crystal were studied effectively. Density functional theory calculations were performed to probe the relationship between the structure and its properties including molecular optimization, Mulliken atomic charge distribution, frontier molecular orbital (FMOs) and molecular electrostatic potential map (MEP) analysis and first hyperpolarizability. All these experimental and computational results were discussed in this communication and it endorsed the ID compound as a potential NLO candidate could be employed in optoelectronics device applications in near future.

Synthesis, growth, structural, thermal and optical studies of pyrrolidinium-2-carboxylate-4-nitrophenol single crystals.

PubMed

Swarna Sowmya, N; Sampathkrishnan, S; Vidyalakshmi, Y; Sudhahar, S; Mohan Kumar, R

2015-06-15

Organic nonlinear optical material, pyrrolidinium-2-carboxylate-4-nitrophenol (PCN) was synthesized and single crystals were grown by slow evaporation solution growth method. Single crystal X-ray diffraction analysis confirmed the structure and lattice parameters of PCN crystals. Infrared, Raman and NMR spectral analyses were used to elucidate the functional groups present in the compound. The thermal behavior of synthesized compound was studied by thermogravimetric and differential scanning calorimetry (TG-DSC) analyses. The photoluminescence property was studied by exciting the crystal at 360 nm. The relative second harmonic generation (SHG) efficiency of grown crystal was estimated by using Nd:YAG laser with fundamental wavelength of 1,064 nm. Copyright © 2015 Elsevier B.V. All rights reserved.

Growth, piezoelectric study and particle size dependent SHG of an 80 mm long SR grown imidazolium l-tartrate single crystals

NASA Astrophysics Data System (ADS)

Jauhar, RO MU; Era, Paavai; Murugakoothan, P.

2018-05-01

Single crystal of imidazolium l-tartrate (IMLT), an organic nonlinear optical material, was successfully grown by slow evaporation solution growth technique (SEST) and Sankaranarayanan - Ramasamy (SR) method. The crystal structure and its lattice parameters were confirmed by single crystal X-ray diffraction study. The IMLT crystal belongs to monoclinic crystal system having a = 7.579(6) Å, b = 6.911(4) Å, c = 8.9281(5) Å, β = 101.45(8)°, volume, V = 458.33 Å3. The d33 coefficient found from the the piezoelectric study is 23 pC/N. The relative second harmonic generation efficiency of IMLT was found to be 3.16 times that of reference KDP material.

Growth and studies of cyclohexylammonium 4-methoxy benzoate single crystal for nonlinear optical applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sathya, P.; Gopalakrishnan, R., E-mail: krgkrishnan@annauniv.edu

2015-06-24

Cyclohexylammonium 4-Methoxy Benzoate (C4MB) was synthesised and the functional groups were confirmed by FTIR analysis. The purified C4MB (by repeated recrystallisation) was used for single crystal growth. Single crystal of cyclohexylammonium 4-methoxy benzoate was successfully grown by slow evaporation solution growth method at ambient temperature. Structural orientations were determined from single crystal X-ray diffractometer. Optical absorption and cut off wavelength were identified by UV-Visible spectroscopy. Thermal stability of the crystal was studied from thermogravimetric and differential thermal analyses curves. Mechanical stability of the grown crystal was analysed by Vicker’s microhardness tester. The Second Harmonic Generation (SHG) study revealed that themore » C4MB compound exhibits the SHG efficiency 3.3 times greater than KDP crystal.« less

Translation effects on vertical Bridgman growth and optical, mechanical and surface analysis of 2-phenylphenol single crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadhasivam, S., E-mail: sadha.phy1@gmail.com; Perumal, Rajesh Narayana

2-phenylphenol optical crystals were grown in cone ampoules using vertical Bridgman technique. Single crystal of 2-phenylphenol with 150 mm length has been grown. The inclination on the conical part of the ampoule reduces the growth defects in the 2-phenylphenol single crystal. The lattice parameters and structure studied using single crystal X-ray diffraction method. 2-phenylphenol single crystal belongs to orthorhombic space group Fdd2. The micro translation rate affects crystal growth of 2-phenylphenol crystal was studied. The translation rate dependent defects present in the crystal were investigated by transmittance, indentation and etching characterizations. The dislocation induced indentation crack lengths variations were studied. Etchmore » pits and striations observed for the selective etchants furnish significant information on growth aspects and degree of defect present in the crystal.« less

Theoretical and experimental morphologies of 4-aminobenzophenone (ABP) crystals

NASA Astrophysics Data System (ADS)

Wang, Qingwu; Sheen, D. B.; Shepherd, E. E. A.; Sherwood, J. N.; Simpson, G. S.; Hammond, R. B.

1997-11-01

The lattice energy (Elatt), slice energies (Eslice) and attachment energies (Eatt) of the different habit faces of ABP crystals have been calculated using the computer program HABIT. On the basis of the attachment energies of different crystal faces, the morphology was defined as {1 0 0}, {0 0 1}, {1 1 0}, {11bar0} and {1 01bar}. To confirm this theoretical prediction, we have grown ABP films and ABP crystals from the vapour phase. In both cases, the morphologically most important face was defined as {1 0 0} face using X-ray diffraction techniques. The remaining faces of the vapour-grown crystals were defined using a projection method, while the crystallites in the films were morphologically analysed by means of atomic force microscopy (AFM). The experimental morphologies are basically in agreement with the computation. Deviations from the equilibrium morphology can be ascribed to departure from equilibrium conditions during growth. For completeness, the results are compared with those for crystals grown from solutions for which deviations in morphology from the theoretical predictions can be ascribed to interaction between the crystal faces and solvent molecules.

Dielectric properties of highly resistive GaN crystals grown by ammonothermal method at microwave frequencies

NASA Astrophysics Data System (ADS)

Krupka, Jerzy; Zajåc, Marcin; Kucharski, Robert; Gryglewski, Daniel

2016-03-01

Permittivity, the dielectric loss tangent and conductivity of semi-insulating Gallium Nitride crystals have been measured as functions of frequency from 10 GHz to 50 GHz and temperature from 295 to 560 K employing quasi TE0np mode dielectric resonator technique. Crystals were grown using ammonothermal method. Two kinds of doping were used to obtain high resistivity crystals; one with deep acceptors in form of transition metal ions, and the other with shallow Mg acceptors. The sample compensated with transition metal ions exhibited semi-insulating behavior in the whole temperature range. The sample doped with Mg acceptors remained semi-insulating up to 390 K. At temperatures exceeding 390 K the conductivity term in the total dielectric loss tangent of Mg compensated sample becomes dominant and it increases exponentially with activation energy of 1.14 eV. It has been proved that ammonothermal method with appropriate doping allows growth of high quality, temperature stable semi-insulating GaN crystals.

Studies on the growth, structural, spectral and third-order nonlinear optical properties of ammonium 3-carboxy-4-hydroxy benzenesulfonate monohydrate single crystal.

PubMed

Silambarasan, A; Krishna Kumar, M; Thirunavukkarasu, A; Mohan Kumar, R; Umarani, P R

2015-01-25

An organic nonlinear optical bulk single crystal, Ammonium 3-carboxy-4-hydroxy benzenesulfonate monohydrate (ACHBS) was successfully grown by solution growth technique. Single crystal X-ray diffraction study confirms that, the grown crystal belongs to P21/c space group. Powder X-ray diffraction and high resolution X-ray diffraction analyses revealed the crystallinity of the grown crystal. Infrared spectral analysis showed the vibrational behavior of chemical bonds and its functional groups. The thermal stability and decomposition stages of the grown crystal were studied by TG-DTA analysis. UV-Visible transmittance studies showed the transparency region and cut-off wavelength of the grown crystal. The third-order nonlinear optical susceptibility of the grown crystal was estimated by Z-scan technique using He-Ne laser source. The mechanical property of the grown crystal was studied by using Vicker's microhardness test. Copyright © 2014 Elsevier B.V. All rights reserved.

ZnTeO{sub 3} crystal growth by a modified Bridgman technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nawash, Jalal M., E-mail: nawashj@uww.edu; Lynn, Kelvin G.

2014-12-15

Highlights: • ZnTeO{sub 3} single crystals were grown for the first time by a modified Bridgman method. • The growth is still possible in a system that lacks congruent melting. • A growth is best when melt is exposed to a steeper axial thermal gradient. • Optical and electrical properties were investigated for the grown crystals. - Abstract: Zinc Tellurite (ZnTeO{sub 3}) crystals were grown for the first time using a modified Bridgman method with a 2.5 kHz radio frequency (RF) furnace. Single crystal growth of ZnTeO{sub 3} was hindered by many complicating factors, such as the evaporation of TeO{submore » 2} above 700 °C and the formation of more than one phase during crystal growth. While there were several successful runs that produced ZnTeO{sub 3} single crystals, it was found that large (≥10 cm{sup 3}) single ZnTeO{sub 3} crystals resulted when the crucible was exposed to a steeper vertical thermal gradient and when the temperature of the melt was raised to at least 860 °C. The results of powder X-ray diffraction (XRD) patterns were in accordance with the X-ray powder diffraction file (PDF) for ZnTeO{sub 3}. Some optical, electrical and structural properties of ZnTeO{sub 3} single crystals were reported in this paper.« less

Efficient Incorporation of Mg in Solution Grown GaN Crystals

NASA Astrophysics Data System (ADS)

Freitas, Jaime A., Jr.; Feigelson, Boris N.; Anderson, Travis J.

2013-11-01

Detailed spectrometry and optical spectroscopy studies carried out on GaN crystals grown in solution detect and identify Mg as the dominant shallow acceptor. Selective etching of crystals with higher Mg levels than that of the donor concentration background indicates that Mg acceptors incorporate preferentially in the N-polar face. Electrical transport measurements verified an efficient incorporation and activation of the Mg acceptors. These results suggest that this growth method has the potential to produce p-type doped epitaxial layers or p-type substrates characterized by high hole concentration and low defect density.

Structural, spectral and birefringence studies of semiorganic nonlinear optical single crystal: Calcium5-sulfosalicylate

NASA Astrophysics Data System (ADS)

Shalini, D.; Kalainathan, S.; Ambika, V. Revathi; Hema, N.; Jayalakshmi, D.

2017-11-01

Semi-organic nonlinear optical crystal Calcium5-Sulfosalicylate (CA5SS) was grown by slow evaporation solution growth technique. The cell parameters and molecular structure of the grown crystal were studied by single crystal x-ray diffraction analysis. The presence of various functional groups of the grown crystal was confirmed using Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman) analysis. UV-Visible spectrum shows that CA5SS crystals have high transmittance in the range of 330-900 nm. The refractive index, birefringence and transient photoluminescence properties of the grown crystal were analyzed. The frequency doubling of the grown crystal (CA5SS) were studied and compared with that of KDP.

Growth and characterization of 4-chloro-3-nitrobenzophenone single crystals using vertical Bridgman technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aravinth, K., E-mail: anandcgc@gmail.com; Babu, G. Anandha, E-mail: anandcgc@gmail.com; Ramasamy, P., E-mail: anandcgc@gmail.com

2014-04-24

4-chloro-3-nitrobenzophenone (4C3N) has been grown by using vertical Bridgman technique. The grown crystal was confirmed by Powder X-ray diffraction analysis. The crystalline perfection of the grown crystal was examined by high-resolution X-ray diffraction study. The fluorescence spectra of grown 4C3N single crystals exhibit emission peak at 575 nm. The micro hardness measurements were used to analyze the mechanical property of the grown crystal.

A preliminary review of organic materials single crystal growth by the Czochralski technique

NASA Astrophysics Data System (ADS)

Penn, B. G.; Shields, A. W.; Frazier, D. O.

1988-09-01

The growth of single crystals of organic compounds by the Czochralski method is reviewed. From the literature it is found that single crystals of benzil, a nonlinear optical material with a d sub 11 value of 11.2 + or - 1.5 x d sub 11 value of alpha quartz, has fewer dislocations than generally contained in Bridgman crystals. More perfect crystals were grown by repeated Czochralski growth. This consists of etching away the defect-containing portion of a Czochralski grown crystal and using it as a seed for further growth. Other compounds used to grow single crystals are benzophenone, 12-tricosanone (laurone), and salol. The physical properties, growth apparatus, and processing conditions presented in the literature are discussed. Moreover, some of the possible advantages of growing single crystals of organic compounds in microgravity to obtain more perfect crystals than on Earth are reviewed.

A preliminary review of organic materials single crystal growth by the Czochralski technique

NASA Technical Reports Server (NTRS)

Penn, B. G.; Shields, A. W.; Frazier, D. O.

1988-01-01

The growth of single crystals of organic compounds by the Czochralski method is reviewed. From the literature it is found that single crystals of benzil, a nonlinear optical material with a d sub 11 value of 11.2 + or - 1.5 x d sub 11 value of alpha quartz, has fewer dislocations than generally contained in Bridgman crystals. More perfect crystals were grown by repeated Czochralski growth. This consists of etching away the defect-containing portion of a Czochralski grown crystal and using it as a seed for further growth. Other compounds used to grow single crystals are benzophenone, 12-tricosanone (laurone), and salol. The physical properties, growth apparatus, and processing conditions presented in the literature are discussed. Moreover, some of the possible advantages of growing single crystals of organic compounds in microgravity to obtain more perfect crystals than on Earth are reviewed.

Influence of Containment on the Growth of Silicon-Germanium (ICESAGE): A Materials Science Investigation

NASA Technical Reports Server (NTRS)

Volz, M. P.; Mazuruk, K.; Croll, A.

2014-01-01

A series of Ge Si crystal growth experiments are planned to be conducted in the Low 1-x x Gradient Furnace (LGF) onboard the International Space Station. The primary objective of the research is to determine the influence of containment on the processing-induced defects and impurity incorporation in germanium-silicon alloy crystals. A comparison will be made between crystals grown by the normal and "detached" Bridgman methods and the ground-based float zone technique. Crystals grown without being in contact with a container have superior quality to otherwise similar crystals grown in direct contact with a container, especially with respect to impurity incorporation, formation of dislocations, and residual stress in crystals. "Detached" or "dewetted" Bridgman growth is similar to regular Bridgman growth in that most of the melt is in contact with the crucible wall, but the crystal is separated from the wall by a small gap, typically of the order of 10-100 microns. Long duration reduced gravity is essential to test the proposed theory of detached growth. Detached growth requires the establishment of a meniscus between the crystal and the ampoule wall. The existence of this meniscus depends on the ratio of the strength of gravity to capillary forces. On Earth, this ratio is large and stable detached growth can only be obtained over limited conditions. Crystals grown detached on the ground exhibited superior structural quality as evidenced by measurements of etch pit density, synchrotron white beam X-ray topography and double axis X-ray diffraction.

Structural and optical effects induced by gamma irradiation on NdPO{sub 4}: X-ray diffraction, spectroscopic and luminescence study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadhasivam, S.; Rajesh, N.P., E-mail: rajeshnp@hotmail.com

2016-02-15

Highlights: • Inorganic NdPO{sub 4} crystal was grown first time using potassium polyphosphate (K{sub 6}P{sub 4}O{sub 13}) flux. • NdPO{sub 4} crystal is insoluble in water, non-hygroscopic and high radiation resistance favoring for actinides host. • Actinide immobilization can be made at 1273 K. • High yield of 1061 nm photon emission. - Abstract: Rare earth orthophosphate (NdPO{sub 4}) monazite single crystals were grown using high temperature flux growth method employing K{sub 6}P{sub 4}O{sub 13} (K{sub 6}) as molten solvent. Their structural parameters were studied using single crystal X-ray diffraction (XRD) method. The grown crystals were examined by SEM andmore » EDX techniques for their homogeniousity and inclusion in the crystals. The influence of gamma irradiation in structural and optical absorption properties were studied by the powder XRD, FTIR and reflectance spectroscopy. The effect of gamma irradiation on luminescence properties was recorded. No significant structural change is observed up to 150 kGy gamma dose. The gamma ray induced charge trap in the crystal was saturated to 40 kGy dose. The luminescence intensity decreases with an increase in the irradiation. The emission of luminescence intensity stabilizes above 40 kGy gamma dose.« less

Comparative analysis of anti-polyglutamine Fab crystals grown on Earth and in microgravity.

PubMed

Owens, Gwen E; New, Danielle M; Olvera, Alejandra I; Manzella, Julia Ashlyn; Macon, Brittney L; Dunn, Joshua C; Cooper, David A; Rouleau, Robyn L; Connor, Daniel S; Bjorkman, Pamela J

2016-10-01

Huntington's disease is one of nine neurodegenerative diseases caused by a polyglutamine (polyQ)-repeat expansion. An anti-polyQ antigen-binding fragment, MW1 Fab, was crystallized both on Earth and on the International Space Station, a microgravity environment where convection is limited. Once the crystals returned to Earth, the number, size and morphology of all crystals were recorded, and X-ray data were collected from representative crystals. The results generally agreed with previous microgravity crystallization studies. On average, microgravity-grown crystals were 20% larger than control crystals grown on Earth, and microgravity-grown crystals had a slightly improved mosaicity (decreased by 0.03°) and diffraction resolution (decreased by 0.2 Å) compared with control crystals grown on Earth. However, the highest resolution and lowest mosaicity crystals were formed on Earth, and the highest-quality crystal overall was formed on Earth after return from microgravity.

Comparative analysis of anti-polyglutamine Fab crystals grown on Earth and in microgravity

PubMed Central

Owens, Gwen E.; New, Danielle M.; Olvera, Alejandra I.; Manzella, Julia Ashlyn; Macon, Brittney L.; Dunn, Joshua C.; Cooper, David A.; Rouleau, Robyn L.; Connor, Daniel S.; Bjorkman, Pamela J.

2016-01-01

Huntington’s disease is one of nine neurodegenerative diseases caused by a polyglutamine (polyQ)-repeat expansion. An anti-polyQ antigen-binding fragment, MW1 Fab, was crystallized both on Earth and on the International Space Station, a microgravity environment where convection is limited. Once the crystals returned to Earth, the number, size and morphology of all crystals were recorded, and X-ray data were collected from representative crystals. The results generally agreed with previous microgravity crystallization studies. On average, microgravity-grown crystals were 20% larger than control crystals grown on Earth, and microgravity-grown crystals had a slightly improved mosaicity (decreased by 0.03°) and diffraction resolution (decreased by 0.2 Å) compared with control crystals grown on Earth. However, the highest resolution and lowest mosaicity crystals were formed on Earth, and the highest-quality crystal overall was formed on Earth after return from microgravity. PMID:27710941

SKYLAB (SL)-3 - EXPERIMENT HARDWARE

NASA Image and Video Library

1973-11-08

S74-19677 (April 1974) --- This crystal of Germanium Selenide (GeSe) was grown under weightless conditions in an electric furnace aboard the Skylab space station. Experiment M556, Vapor Growth of IV-VI Compounds, was conducted as a comparative test of GeSe crystals grown on Earth and those grown in a weightless environment. Skylab postflight results indicate that crystals grown in a zero-gravity situation demonstrate greater growth and better composite structure than those grown in ground-bases laboratories. The GeSe crystal shown here is 20 millimeters long, the largest crystal ever grown on Earth or in space. Principal Investigator for Experiment M556 is Dr. Harry Wiedemaier, Rensselaer Polytechnic Institute, Troy, New York. (See NASA photograph S74-19676 for an example of an Earth-grown Germanium Selenide crystal.) Photo credit: NASA

Growth of L-Valinium Aluminium Chloride single crystal for OLED and super-capacitor applications

NASA Astrophysics Data System (ADS)

Kalaivani, D.; Vijayalakshmi, S.; Theras, J. Elberin Mary; Jayaraman, D.; Joseph, V.

2015-12-01

L-Valinium Aluminium Chloride (LVAC), a novel semi-organic material, was grown using slow evaporation under isothermal condition. The single crystal data reveal that the grown crystal belongs to monoclinic system. The SEM micrographs give clear picture about the surface morphology. Further, they confirm the inclusion of aluminium chloride into atomic sites of L-Valine. The compositional elements present in the crystal were identified through EDAX analysis. The mass spectral analysis was carried out to determine the molecular weight of the grown crystal. The optical transparency of the grown crystal was investigated by UV-vis-NIR spectrum. FTIR spectral study was used to identify the functional groups present in the grown material. The luminescence characteristics of grown material were analysed to confirm the effect of metal ion on the ligand. This property makes the material suitable for OLED application. The supercapacitive performance of the grown crystal was finally studied using cyclic voltammetry.

High resolution diffraction imaging of crystals grown in microgravity and closely related terrestrial crystals

NASA Technical Reports Server (NTRS)

Steiner, B.; Dobbyn, R.; Black, D.; Burdette, H.; Kuriyama, M.; Spal, R.; Vandenberg, L.; Fripp, A.; Simchick, R.; Lal, R.

1991-01-01

Irregularities found in three crystals grown in space, in four crystals grown entirely on the ground were examined and compared. Irregularities were observed in mercuric iodide, lead tin telluride, triglycine sulfate, and gallium arsenide by high resolution synchrotron x radiation diffraction imaging. Radiation detectors made from mercuric iodide crystals grown in microgravity were reported to perform far better than conventional detectors grown from the same material under full gravity. Effort is now underway to reproduce these 'space' crystals, optimize their properties, and extend comparable superiority to other types of materials.

Growth and characterization of organic NLO material: Clobetasol propionate

NASA Astrophysics Data System (ADS)

Purusothaman, R.; Rajesh, P.; Ramasamy, P.

2015-06-01

Single crystals of clobetasol propionate (CP) have been grown by slow evaporation solution technique using mixed solvent of methanol-acetone. The grown crystals were subjected to single crystal X-ray diffraction analysis to confirm their lattice parameter and space group. The powder X-ray diffraction pattern of the grown CP has been indexed. Thermal analysis was performed to study the thermal stability of the grown crystals. Photoluminescence spectrum shows broad emission peak observed at 421 nm. Nonlinear optical studies were carried out for the grown crystal and second harmonic generation (SHG) efficiency was found in the crystal.

TlBr purification and single crystal growth for the detector applications

NASA Astrophysics Data System (ADS)

Kozlov, Vasilij; Heikkilä, Mikko; Kostamo, Pasi; Lipsanen, Harri; Leskelä, Markku

2011-05-01

The combination of distillation, Bridgman-Stockbarger, hydrothermal recrystallisation and travelling molten zone (TMZ) methods were used for TlBr purification. Grown crystals were characterised by XRD rocking curve and FTIR spectroscopy methods, and by electrical measurements made from 200 to 300 K.

Growth of single crystals from solutions using semi-permeable membranes

NASA Astrophysics Data System (ADS)

Varkey, A. J.; Okeke, C. E.

1983-05-01

A technique suitable for growth of single crystals from solutions using semi-preamble membranes is described. Using this technique single crystals of copper sulphate, potassium bromide and ammonium dihydrogen phosphate have been successfully grown. Advantages of this technique over other methods are discussed.

Structural and spectroscopic investigation of glycinium oxalurate

NASA Astrophysics Data System (ADS)

Kavitha, T.; Pasupathi, G.; Marchewka, M. K.; Anbalagan, G.; Kanagathara, N.

2017-09-01

Glycinium oxalurate (GO) single crystals has been synthesized and grown by the slow solvent evaporation method at room temperature. Single crystal X-ray diffraction study confirms that GO crystal crystallizes in the monoclinic system with centrosymmetric space group P121/c1. The grown crystals are built up from single protonated glycinium residues and single dissociated oxalurate anions. A combination of ionic and donor-acceptor hydrogen-bond interactions linking together the glycine and oxaluric acid residues forms a three-dimensional network. Hydrogen bonded network present in the crystal gives notable vibrational effect. The molecular geometry, vibrational frequencies and intensity of the vibrational bands have been interpreted with the aid of structure optimization based on HF and density functional theory B3LYP methods with 6-311++G(d,p) basis set. Frontier molecular orbital energies and other related electronic properties are calculated. The natural bonding orbital (NBO) charges have been calculated and interpreted. The molecular electrostatic potential map has been constructed and discussed in detail.

Electrochemical growth of linear conducting crystals in microgravity

NASA Technical Reports Server (NTRS)

Cronise, Raymond J., IV

1988-01-01

Much attention has been given to the synthesis of linear conducting materials. These inorganic, organic, and polymeric materials have some very interesting electrical and optical properties, including low temperature superconductivity. Because of the anisotropic nature of these compounds, impurities and defects strongly influences the unique physical properties of such crystals. Investigations have demonstrated that electrochemical growth has provided the most reproducible and purest crystals. Space, specifically microgravity, eliminates phenomena such as buoyancy driven convection, and could permit formation of crystals many times purer than the ones grown to date. Several different linear conductors were flown on Get Away Special G-007 on board the Space Shuttle Columbia, STS 61-C, the first of a series of Project Explorer payloads. These compounds were grown by electrochemical methods, and the growth was monitored by photographs taken throughout the mission. Due to some thermal problems, no crystals of appreciable size were grown. The experimental results will be incorporated into improvements for the next 2 missions of Project Explorer. The results and conclusions of the first mission are discussed.

Synthesis, structural, spectroscopic and optical studies of charge transfer complex salts.

PubMed

Manikandan, Maruthappan; Mahalingam, Thaiyan; Hayakawa, Yasuhiro; Ravi, Ganesan

2013-01-15

New charge transfer molecular complex adducts of picric acid (C6H3N3O7) with triethylamine (C6H15N) and dimethylformamide (HCON(CH3)2) were synthesized successfully for the first time. Chemical composition and stoichiometry of the synthesized complex salts were verified by CHN elemental analysis. Solubility of the complex salts have been determined by gravimetric method and single crystals of two new salts were grown by low temperature solution growth technique. Crystal system, crystalline nature and cell parameters of the grown crystals were determined by single crystal X-ray diffraction (SXRD) and powder X-ray diffraction (PXRD) analyses. The formations of the charge-transfer complex, functional groups and the modes of vibrations have been confirmed by Fourier transform infrared (FTIR) spectroscopy. In order to know the linear and nonlinear optical suitability for device fabrication, UV-Vis (UV) spectral analysis and relative second harmonic generation (SHG) efficiency test were performed for the grown crystals. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis, structural, spectroscopic and optical studies of charge transfer complex salts

NASA Astrophysics Data System (ADS)

Manikandan, Maruthappan; Mahalingam, Thaiyan; Hayakawa, Yasuhiro; Ravi, Ganesan

2013-01-01

New charge transfer molecular complex adducts of picric acid (C6H3N3O7) with triethylamine (C6H15N) and dimethylformamide (HCON(CH3)2) were synthesized successfully for the first time. Chemical composition and stoichiometry of the synthesized complex salts were verified by CHN elemental analysis. Solubility of the complex salts have been determined by gravimetric method and single crystals of two new salts were grown by low temperature solution growth technique. Crystal system, crystalline nature and cell parameters of the grown crystals were determined by single crystal X-ray diffraction (SXRD) and powder X-ray diffraction (PXRD) analyses. The formations of the charge-transfer complex, functional groups and the modes of vibrations have been confirmed by Fourier transform infrared (FTIR) spectroscopy. In order to know the linear and nonlinear optical suitability for device fabrication, UV-Vis (UV) spectral analysis and relative second harmonic generation (SHG) efficiency test were performed for the grown crystals.

Compound semi-conductors and controlled doping thereof

NASA Technical Reports Server (NTRS)

Larkin, David J. (Inventor); Neudeck, Philip G. (Inventor); Powell, J. Anthony (Inventor); Matus, Lawrence G. (Inventor)

1998-01-01

A method of controlling the amount of impurity incorporation in a crystal grown by a chemical vapor deposition process. Conducted in a growth chamber, the method includes the controlling of the concentration of the crystal growing components in the growth chamber to affect the demand of particular growth sites within the growing crystal thereby controlling impurity incorporation into the growth sites.

A novel organic nonlinear optical crystal: Creatininium succinate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thirumurugan, R.; Anitha, K., E-mail: singlecerystalxrd@gmail.ciom

2015-06-24

A novel organic material complex of creatininium succinate (CS) has been synthesized and single crystals were grown by the reaction of creatinine and succinic acid from aqueous solution by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated using single crystal X-ray diffraction analysis and the structure was refined by least-squares method to R = 0.027 for 1840 reflections. FT-IR spectral investigation has been carried out to identify the various functional groups in the title compound. UV–Vis transmission was carried out which shows the crystal has a good optical transmittance inmore » the visible region with lower cutoff wavelength around 220 nm. Nonlinear optical property of the crystal was confirmed by Kurtz-Perry powder technique.« less

Growth and characterization of new semiorganic nonlinear optical and piezoelectric lithium sulfate monohydrate oxalate single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yadav, Harsh; Sinha, Nidhi; Kumar, Binay, E-mail: b3kumar69@yahoo.co.in

2015-04-15

Highlights: • A new semiorganic single crystal of LSO grown by slow evaporation technique. • Morphological studies of the LSO crystal deduced by BFDH law. • In the UV–vis spectrum wide transparent region and large band gap were found. • SHG is equal to KDP crystal and d{sub 33} was found to be equal to 6pC/N. • Grown crystal belongs to softer category. - Abstract: New semiorganic crystal of lithium sulfate monohydrate oxalate (LSO) for nonlinear application was synthesized by controlled slow evaporation method. The growth rate of various planes of the grown crystal was estimated by morphological study. Singlemore » crystal XRD analysis confirmed that the crystal belongs to triclinic lattice with space group P1. High transparency (∼95%) with large band gap (4.57 eV) was analyzed by UV–vis studies. FTIR and Raman spectroscopy were used to identify various functional groups present in the LSO crystal. SHG efficiency was found to be equal to the KDP crystal. Thermal stability (up to 117.54 °C) and melting point (242 °C) of the crystal were studied by TG-DTA. In dielectric measurements, the value of dielectric constant decreases with increase in frequency. Hardness studies confirmed soft nature of crystals. The piezoelectric coefficient was found to be 6pC/N along [0 0 1].« less

Crystal growth and characterization of semi organic nonlinear optical (NLO) piperazinium tetrachlorozincate monohydrate (PTCZ) single crystal

NASA Astrophysics Data System (ADS)

Karuppasamy, P.; Pandian, Muthu Senthil; Ramasamy, P.

2018-04-01

The semi-organic single crystal of piperazinium tetrachlorozincate monohydrate (PTCZ) was successfully grown by slow evaporation solution technique (SEST). The grown crystal was subjected to the single crystal XRD studies for confirming the unit cell parameters. The optical quality of the grown crystal was identified by the UV-Vis NIR spectrum analysis and the optical band gap energy was calculated. The photoconductivity study reveals that the grown crystal has positive photoconductive nature. The mechanical stability of the grown crystal was analyzed using Vickers microhardness analyzer. The third-order nonlinear optical properties such as nonlinear refractive index (n2), absorption co-efficient (β) and susceptibility (χ(3)) were studied by Z-scan technique at 640 nm using solid state laser.

Laser radiation frequency doubling in a single-crystal fibre based on a stoichiometric LiNbO3 crystal

NASA Astrophysics Data System (ADS)

Kashin, V. V.; Nikolaev, D. A.; Rusanov, S. Ya; Tsvetkov, V. B.

2015-01-01

We demonstrate the employment of single-crystal optical fibres based on lithium niobate for doubling the laser radiation frequency. The measured characteristics of the fibre confirm its high quality and spatial homogeneity. Parameters of the frequency doublers for neodymium laser radiation (λ = 1 mm) based on fibre and bulk single crystals are compared. Single crystals are grown by the method of laser-heated pedestal growing with heating by radiation of a CO2 laser (LHPG-method).

Apoferritin crystals

NASA Technical Reports Server (NTRS)

2001-01-01

Dr. Alexander Chernov, of the Universities Space Research Association (USRA) and based at Marshall Space Flight Center, is investigating why protein crystals grown in space are, in about 20 percent of cases, better-ordered than those grown on the ground. They are testing the idea that the amount of impurities trapped by space-grown crystals may be different than the amount trapped by crystals grown on Earth because convection is negligible in microgravity. The concentrations or impurities in many space-grown crystals turned out to be several times lower than that in the terrestrial ones, sometimes below the detection limit. The ground-based experiment also showed that the amount of impurities per unit volume of the crystals was usually higher than the amount per unit volume of the solution. This means that a growing crystal actually purifies the solution in its immediate vicinity. Here, an impurity depletion zone is created around apoferritin crystals grown in gel, imitating microgravity conditions.

Characterization of zinc selenide single crystals

NASA Technical Reports Server (NTRS)

Gerhardt, Rosario A.

1996-01-01

ZnSe single crystals of high quality and low impurity levels are desired for use as substrates in optoelectronic devices. This is especially true when the device requires the formation of homoepitaxial layers. While ZnSe is commercially available, it is at present extremely expensive due to the difficulty of growing single crystal boules with low impurity content and the resultant low yields. Many researchers have found it necessary to heat treat the crystals in liquid Zn in order to remove the impurities, lower the resistivity and activate the photoluminescence at room temperature. The physical vapor transport method (PVT) has been successfully used at MSFC to grow many single crystals of II-VI semiconducting materials including ZnSe. The main goal at NASA has been to try to establish the effect of gravity on the growth parameters. To this effect, crystals have been grown vertically upwards or horizontally. Both (111) and (110) oriented ZnSe crystals have been obtained via unseeded PVT growth. Preliminary characterization of the horizontally grown crystals has revealed that Cu is a major impurity and that the low temperature photoluminescence spectra is dominated by the copper peak. The ratio of the copper peak to the free exciton peak is being used to determine variations in composition throughout the crystal. It was the intent of this project to map the copper composition of various crystals via photoluminescence first, then measure their electrical resistivity and capacitance as a function of frequency before proceeding with a heat treatment designed to remove the copper impurities. However, equipment difficulties with the photoluminescence set up, having to establish a procedure for measuring the electrical properties of the as-grown crystals and time limitations made us re-evaluate the project goals. Vertically grown samples designated as ZnSe-25 were chosen to be measured electrically since they were not expected to show as much variation in their composition through their cross-section as the horizontally grown samples.

Generation of Protein Crystals Using a Solution-Stirring Technique

NASA Astrophysics Data System (ADS)

Adachi, Hiroaki; Niino, Ai; Matsumura, Hiroyoshi; Takano, Kazufumi; Kinoshita, Takayoshi; Warizaya, Masaichi; Inoue, Tsuyoshi; Mori, Yusuke; Sasaki, Takatomo

2004-06-01

Crystals of bovine adenosine deaminase (ADA) were grown over a two week period in the presence of an inhibitor, whereas ADA crystals did not form using conventional crystallization methods when the inhibitor was excluded. To obtain ADA crystals in the absence of the inhibitor, a solution-stirring technique was used. The crystals obtained using this technique were found to be of high quality and were shown to have high structural resolution for X-ray diffraction analysis. The results of this study indicate that the stirring technique is a useful method for obtaining crystals of proteins that do not crystallize using conventional techniques.

Structural, thermal and optical characterization of an organic NLO material--benzaldehyde thiosemicarbazone monohydrate single crystals.

PubMed

Santhakumari, R; Ramamurthi, K

2011-02-01

Single crystals of the organic NLO material, benzaldehyde thiosemicarbazone (BTSC) monohydrate, were grown by slow evaporation method. Solubility of BTSC monohydrate was determined in ethanol at different temperatures. The grown crystals were characterized by single crystal X-ray diffraction analysis to determine the cell parameters and by FT-IR technique to study the presence of the functional groups. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. UV-vis-NIR spectrum shows excellent transmission in the region of 200-1100 nm. Theoretical calculations were carried out to determine the linear optical constants such as extinction coefficient and refractive index. Further the optical nonlinearities of BTSC have been investigated by Z-scan technique with He-Ne laser radiation of wavelength 632.8 nm. Mechanical properties of the grown crystal were studied using Vickers microhardness tester. Second harmonic generation efficiency of the powdered BTSC monohydrate was tested using Nd:YAG laser and it is found to be ∼5.3 times that of potassium dihydrogen orthophosphate. Copyright © 2010 Elsevier B.V. All rights reserved.

Growth, structural, thermal, dielectric and nonlinear optical properties of potassium hexachloro cadmate (IV) a novel single crystal

NASA Astrophysics Data System (ADS)

Umarani, P.; Jagannathan, K.

2018-02-01

The Potassium hexachloro cadmate (IV) (PHC) single crystal was grown from the aqueous of the solution by a controlled evaporation method. Single crystal XRD solved the structure. FTIR is used to identify the functional groups of grown crystal. The UV-Vis-NIR spectrometer was used to find out the UV cut off region and to calculate the optical band gap of the Potassium hexachloro cadmate (IV) single crystal. The EDAX spectrum has been used to identify the compounds present in title compound. The TG-DTA profile shows the thermal stability of the grown crystal of Potassium hexachloro cadmate (IV). The Vicker's hardness measurement was used to calculate the material hardness of the title compound. The dielectric loss and constant varied with frequencies and activation energy is also calculated. The solid state parameters like plasma energy, Penn gap, Fermi energy, electronic polarizability using Penn analysis and Clausius-Mossotti equation were also calculated for the title compound. The Z-scan technique is used to calculate the third order nonlinear susceptibility of a real and imaginary part.

Synthesis, structural and optical properties, ferromagnetic behaviour, cytotoxicity and NLO activity of lithium sulphate doped L-threonine

NASA Astrophysics Data System (ADS)

Theras, J. Elberin Mary; Kalaivani, D.; Mani, J. Arul Martin; Jayaraman, D.; Joseph, V.

2016-09-01

Lithium Sulphate doped L-threonine (Li2SO4-LT), a semi-organic crystal, has been synthesised and grown by slow evaporation technique at room temperature. The grown crystal was subjected to single crystal X-ray diffraction analysis in order to establish their crystalline nature. Li2SO4-LT crystal belongs to the orthorhombic crystal system (a=7.66 Å, b=5.11 Å, c=13.60 Å) with space group P212121. Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) study was carried out to quantify the concentration of lithium element in the grown crystal. The results show that 0.07 mol of lithium sulphate has been incorporated into the parent system. The grown material has been found to possess wide transparency in the range 240-1100 nm with lower cut-off wavelength at 240 nm. The optical band gap was calculated as 4.92 eV using optical absorption spectrum and Tauc's relation. Fourier transform infrared (FTIR) spectroscopic study was performed to identify the functional groups present in the grown crystal. The surface features of the grown crystal were analyzed using Scanning Electron Microscope (SEM) analysis. The magnetic property was studied with the help of Vibrating Sample Magnetometer (VSM). The coercivity and retentivity of the material were measured from the hysteresis curve as 550.06 G and 79.50×10-6 emu respectively. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay method was performed to understand the cytotoxicity or anticancer activity of the sample. The cell viability and cytotoxicity of the sample against MCF-7 cells were estimated as 49.41% and 50.59% respectively at a concentration of 250 μg. The second harmonic generation (SHG) efficiency was measured by the Kurtz powder technique using Nd:YAG laser and was found to be 1.46 times that of standard potassium dihydrogen phosphate (KDP).

Solution-grown crystals for neutron radiation detectors, and methods of solution growth

DOEpatents

Zaitseva, Natalia; Carman, M Leslie; Payne, Steve

2014-10-28

An organic crystal according to one embodiment includes an organic crystal comprising diphenylacetylene and stilbene or a stilbene derivative, the crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source. A system according to one embodiment includes an organic crystal comprising diphenylacetylene and stilbene or a stilbene derivative, the crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source; and a photodetector for detecting the signal response of the organic crystal. Methods of making such crystals are also provided.

Synthesis, growth, structural and optical studies of organic nonlinear optical material--piperazine-1,4-diium bis 2,4,6-trinitrophenolate.

PubMed

Suguna, S; Anbuselvi, D; Jayaraman, D; Nagaraja, K S; Jeyaraj, B

2014-11-11

Piperazine-1,4-diium bis 2,4,6-trinitrophenolate is one of the useful organic materials with nonlinear optical (NLO) and pharmaceutical applications. The material was grown by slow evaporation solution growth method at room temperature. The crystal system and lattice parameters were identified by single crystal XRD analysis. The grown material crystallizes in monoclinic system with P21/n space group. The main functional groups NH2, NO2, CN, CC, and phenolic 'O' atom were identified using FTIR analysis. The protons and carbons of grown crystal with various chemical environments were studied by 1H and 13C NMR spectroscopy to confirm the molecular structure. The optical properties of the crystal were studied by UV-vis-NIR spectroscopy and the transmission 100% range starts from 532 nm onwards. The optical band gap was measured as 2.63 eV from the plot of (αhν)2 versus hν. The thermal stability was detected at 304.1°C using TG-DTA analysis. The dielectric studies of the sample were carried out at different temperatures in the frequency range from 50 Hz to 5 MHz to establish the dielectric nature of the crystal. Photoconductivity measurements were carried out on the grown crystal. The Second Harmonic Generation (SHG) of the crystal was tested to confirm the nonlinear optical property. Copyright © 2014 Elsevier B.V. All rights reserved.

Optical, mechanical and thermal behaviors of Nitrilotriacetic acid single crystal

NASA Astrophysics Data System (ADS)

Deepa, B.; Philominathan, P.

2017-11-01

An organic nonlinear single crystal of Nitrilotriacetic acid (NTAA) was grown for the first time by employing a simple slow evaporation technique. Single crystal X-ray diffraction (XRD) analysis reveals that the grown crystal belongs to the monoclinic system with noncentrosymmetric space group CC. Fourier transform infrared (FTIR) spectral study ascertains the presence of functional groups in NTAA. The molecular structure of the grown crystal was confirmed by Nuclear Magnetic Resonance (NMR) spectral analysis. The optical parameters such as transmittance, absorption coefficient and band gap were calculated from UV-Visible and fluorescence studies. Dielectric measurements were carried out for different frequency and temperature. The mechanical strength of the grown crystal was measured using Vickers microhardness test. The high thermal stability and the melting point of the grown crystal were also estimated using thermogravimetric (TGA) and differential thermal analyses (DTA). The confirmation of the grown crystals belonging to nonlinear optical crystals was performed by Kurtz-Perry technique and found as suitable candidate for optoelectronics applications.

Crystal growth, structural, optical, thermal, mechanical, laser damage threshold and electrical properties of triphenylphosphine oxide 4-nitrophenol (TP4N) single crystals for nonlinear optical applications

NASA Astrophysics Data System (ADS)

Karuppasamy, P.; Senthil Pandian, Muthu; Ramasamy, P.; Verma, Sunil

2018-05-01

The optically good quality single crystals of triphenylphosphine oxide 4-nitrophenol (TP4N) with maximum dimension of 15 × 10 × 5 mm3 were grown by slow evaporation solution technique (SEST) at room temperature. The cell dimensions of the grown TP4N crystal were confirmed by single crystal X-ray diffraction (SXRD) and the crystalline purity was confirmed and planes were indexed by powder X-ray diffraction (PXRD) analysis. Functional groups of TP4N crystal were confirmed by Fourier transform infrared (FTIR) spectral analysis. The optical transmittance of the grown crystal was determined by the UV-Vis NIR spectral analysis and it has good optical transparency in the entire visible region. The band tail (Urbach) energy of the grown crystal was analyzed and it appears to be minimum, which indicates that the TP4N has good crystallinity. The position of valence band (Ev) and conduction band (Ec) of the TP4N have been determined from the electron affinity energy (EA) and the ionization energy (EI) of its elements and using the optical band gap. The thermal behaviour of the grown crystal was investigated by thermogravimetric and differential thermal analysis (TG-DTA). Vickers microhardness analysis was carried out to identify the mechanical stability of the grown crystal and their indentation size effect (ISE) was explained by the Meyer's law (ML), Hays-Kendall's (HK) approach, proportional specimen resistance (PSR) model, modified PSR model (MPSR), elastic/plastic deformation (EPD) model and indentation induced cracking (IIC) model. Chemical etching study was carried out to find the etch pit density (EPD) of the grown crystal. Laser damage threshold (LDT) value was measured by using Nd:YAG laser (1064 nm). The dielectric permittivity (ε՛) and dielectric loss (tan δ) as a function of frequency was measured. The electronic polarizability (α) of the TP4N crystal was calculated. It is well matched to the value which was calculated from Clausius-Mossotti relation, Lorentz-Lorentz equation, optical band gap and coupled dipole method (CDM). The Z-scan technique was carried out using solid state laser (640 nm) to analyze the nonlinear optical properties of the TP4N crystal. It exhibits the self-defocusing and saturable absorbance effect during analysis of closed and open aperture respectively. The nonlinear optical parameters such as refractive index (n2), absorption coefficient (β) and the third order nonlinear optical susceptibility (χ(3)) were analyzed.

The application of crystal soaking technique to study the effect of zinc and cresol on insulinotropin crystals grown from a saline solution.

PubMed

Kim, Y; Haren, A M

1995-11-01

The purpose of this study is to investigate the effect of zinc and cresol on the structure of insulinotropin crystals. Insulinotropin crystals grown from a saline solution were treated with zinc and/or m-cresol using a crystal soaking technique. The effects of these additives on the crystal structure were investigated with powder X-ray diffraction, photomicrography, and differential scanning calorimetry. The molecular interaction between insulinotropin and m-trifluorocresol in solution was also studied by 19F NMR: The data suggest that the original crystals grown from a saline solution have relatively weak lattice forces. After the addition of m-cresol to the suspension of the insulinotropin crystals, the crystals were immediately rendered amorphous. The m-cresol molecules which diffused into the crystals through solvent channels may have disturbed the lattice interactions that maintain the integrity of the crystal. In contrast, the zinc added to the suspension stabilized the crystal lattice so that the subsequent addition of m-cresol did not alter the integrity of the crystals. A marked increase in melting point (206 degrees versus 184 degrees) and heat of fusion (24.6 J/g versus 1.4 J/g) of the crystals was observed after the treatment with zinc. The solubility of the zinc treated crystals in a pH 7.1 phosphate buffered saline was 1/20 of that of the original crystals. When the insulinotropin crystals were treated with the additives using a crystal soaking method, the crystals underwent structural changes. Zinc stabilized the crystal lattice, and reduced the solubility of the peptide.

Synthesis, structural, thermal and optical studies of 1-ethyl-2,6-dimethyl-4-hydroxy pyridinium halides.

PubMed

Dhanuskodi, S; Manivannan, S; Kirschbaum, K

2006-05-15

1-Ethyl-2,6-dimethyl-4-hydroxy pyridinium chloride dihydrate and bromide dihydrate salts have been synthesized and their single crystals were grown by the slow evaporation of aqueous solution at 30 degrees C. The grown crystals were characterized by elemental analysis, FT-NMR and FT-IR techniques to confirm the formation of the expected compound. Optical transmittance window in aqueous solution was found to be 275-1100 nm by UV-vis-NIR technique. Thermogravimetric and differential thermal analyses reveal thermal stability and the presence of two water molecules in the crystal lattices. The crystal structure of chloride salt was also determined by X-ray diffraction method.

Crystal growth and scintillation properties of Pr-doped SrI2 single crystals

NASA Astrophysics Data System (ADS)

Yokota, Yuui; Ito, Tomoki; Yoshino, Masao; Yamaji, Akihiro; Ohashi, Yuji; Kurosawa, Shunsuke; Kamada, Kei; Yoshikawa, Akira

2018-04-01

Pr-doped SrI2 (Pr:SrI2) single crystals with various Pr concentrations were grown by the halide-micro-pulling-down (H-μ-PD) method, and the scintillation properties were investigated. Pr1%:SrI2 single crystal with high transparency could be grown by the H-μ-PD method while Pr2, 3 and 5%:SrI2 single crystals included some cracks and opaque parts. In the photoluminescence spectrum of the Pr1%:SrI2 single crystal, an emission peak originated from the Pr3+ ion was observed around 435 nm while the radioluminescence spectra showed an emission peak around 535 nm for the undoped SrI2 and Pr:SrI2 single crystals. Light yields of Pr1, 2, 3 and 5%:SrI2 single crystals under γ-ray irradiation were 7700, 8700, 7200 and 6700 photons/MeV, respectively. Decay times of Pr1 and 2%:SrI2 single crystals under γ-ray irradiation were 55.9 and 35.0 ns of the fast decay component, and 435 and 408 ns of the slow decay component, respectively.

Crystal structure, optical and thermal studies of a new organic nonlinear optical material: L-Histidinium maleate 1.5-hydrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonsago, C. Alosious; Albert, Helen Merina; Karthikeyan, J.

2012-07-15

Highlights: ► L-Histidinium maleate 1.5-hydrate, a new organic crystal has been grown for the first time. ► The crystal structure is reported for the first time (CCDC 845975). ► The crystal belongs to monoclinic system with space group P2{sub 1}, Z = 4, a = 11.4656(7) Å, b = 8.0530(5) Å, c = 14.9705(9) Å and β = 101.657(2)°. ► The optical absorption study substantiates the complete transparency of the crystal. ► Kurtz powder SHG test confirms the nonlinear property of the crystal. -- Abstract: A new organic nonlinear optical material L-histidinium maleate 1.5-hydrate (LHM) with the molecular formula C{submore » 10}H{sub 16}N{sub 3}O{sub 7.5} has been successfully synthesized from aqueous solution by slow solvent evaporation method. The structural characterization of the grown crystal was carried out by single crystal X-ray diffraction at 293(2) K. In the crystal, molecules are linked through inter and intramolecular N-H⋯O and O-H⋯O hydrogen bonds, generate edge fused ring motif. The hydrogen bonded motifs are linked to each other to form a three dimensional network. The FT-IR spectroscopy was used to identify the functional groups of the synthesized compound. The optical behavior of the grown crystal was examined by UV–visible spectral analysis, which shows that the optical absorption is almost negligible in the wavelength range 280–1300 nm. The nonlinear optical property was confirmed by the powder technique of Kurtz and Perry. The thermal behavior of the grown crystal was analyzed by thermogravimetric analysis.« less

Apparatus for growing HgI.sub.2 crystals

DOEpatents

Schieber, Michael M.; Beinglass, Israel; Dishon, Giora

1978-01-01

A method and horizontal furnace for vapor phase growth of HgI.sub.2 crystals which utilizes controlled axial and radial airflow to maintain the desired temperature gradients. The ampoule containing the source material is rotated while axial and radial air tubes are moved in opposite directions during crystal growth to maintain a desired distance and associated temperature gradient with respect to the growing crystal, whereby the crystal interface can advance in all directions, i.e., radial and axial according to the crystallographic structure of the crystal. Crystals grown by this method are particularly applicable for use as room-temperature nuclear radiation detectors.

Protein crystal growth in low gravity

NASA Technical Reports Server (NTRS)

Feigelson, Robert S.

1993-01-01

This Final Technical Report for NASA Grant NAG8-774 covers the period from April 27, 1989 through December 31, 1992. It covers five main topics: fluid flow studies, the influence of growth conditions on the morphology of isocitrate lyase crystals, control of nucleation, the growth of lysozyme by the temperature gradient method and graphoepitaxy of protein crystals. The section on fluid flow discusses the limits of detectability in the Schlieren imaging of fluid flows around protein crystals. The isocitrate lyase study compares crystals grown terrestrially under a variety of conditions with those grown in space. The controlling factor governing the morphology of the crystals is the supersaturation. The lack of flow in the interface between the drop and the atmosphere in microgravity causes protein precipitation in the boundary layer and a lowering of the supersaturation in the drop. This lowered supersaturation leads to improved crystal morphology. Preliminary experiments with lysozyme indicated that localized temperature gradients could be used to nucleate crystals in a controlled manner. An apparatus (thermonucleator) was designed to study the controlled nucleation of protein crystals. This apparatus has been used to nucleate crystals of materials with both normal (ice-water, Rochelle salt and lysozyme) and retrograde (horse serum albumin and alpha chymotrypsinogen A) solubility. These studies have lead to the design of an new apparatus that small and more compatible with use in microgravity. Lysozyme crystals were grown by transporting nutrient from a source (lysozyme powder) to the crystal in a temperature gradient. The influence of path length and cross section on the growth rate was demonstrated. This technique can be combined with the thermonucleator to control both nucleation and growth. Graphoepitaxy utilizes a patterned substrate to orient growing crystals. In this study, silicon substrates with 10 micron grooves were used to grow crystals of catalase, lysozyme and canavalin. In all cases, the crystals grew oriented to the substrate. The supersaturation needed for nucleation and growth was lower on the patterned substrates. In some cases, isolated, large crystals were grown.

Reduction of Defects in Germanium-Silicon

NASA Technical Reports Server (NTRS)

2003-01-01

Crystals grown without contact with a container have far superior quality to otherwise similar crystals grown in direct contact with a container. In addition to float-zone processing, detached- Bridgman growth is a promising tool to improve crystal quality, without the limitations of float zoning or the defects introduced by normal Bridgman growth. Goals of this project include the development of the detached Bridgman process to be reproducible and well understood and to quantitatively compare the defect and impurity levels in crystals grown by these three methods. Germanium (Ge) and germanium-silicon (Ge-Si) alloys are being used. At MSFC, we are responsible for the detached Bridgman experiments intended to differentiate among proposed mechanisms of detachment, and to confirm or refine our understanding of detachment. Because the contact angle is critical to determining the conditions for detachment, the sessile drop method was used to measure the contact angles as a function of temperature and composition for a large number of substrates made of potential ampoule materials. Growth experiments have used pyrolytic boron nitride (pBN) and fused silica ampoules with the majority of the detached results occurring predictably in the pBN. Etch pit density (EPD) measurements of normal and detached Bridgman-grown Ge samples show a two order of magnitude improvement in the detached-grown samples. The nature and extent of detachment is determined by using profilometry in conjunction with optical and electron microscopy. The stability of detachment has been analyzed, and an empirical model for the conditions necessary to achieve sufficient stability to maintain detached growth for extended periods has been developed. We have investigated the effects on detachment of ampoule material, pressure difference above and below the melt, and Si concentration; samples that are nearly completely detached can be grown repeatedly in pBN. Current work is concentrated on developing a method to make in situ pressure measurements in the growth ampoules.

Influence of Containment on the Growth of Silicon-Germanium (ICESAGE): A Materials Science ISS Investigation

NASA Technical Reports Server (NTRS)

Volz, M. P.; Mazuruk, K.; Croll, A.

2014-01-01

A series of Ge(1-x)Si(x) crystal growth experiments are planned to be conducted in the Low Gradient Furnace (LGF) onboard the International Space Station. The primary objective of the research is to determine the influence of containment on the processinginduced defects and impurity incorporation in germanium-silicon alloy crystals. A comparison will be made between crystals grown by the normal and "detached" Bridgman methods and the ground-based float zone technique. Crystals grown without being in contact with a container have superior quality to otherwise similar crystals grown in direct contact with a container, especially with respect to impurity incorporation, formation of dislocations, and residual stress in crystals. "Detached" or "dewetted" Bridgman growth is similar to regular Bridgman growth in that most of the melt is in contact with the crucible wall, but the crystal is separated from the wall by a small gap, typically of the order of 10-100 microns. Long duration reduced gravity is essential to test the proposed theory of detached growth. Detached growth requires the establishment of a meniscus between the crystal and the ampoule wall. The existence of this meniscus depends on the ratio of the strength of gravity to capillary forces. On Earth, this ratio is large and stable detached growth can only be obtained over limited conditions. Crystals grown detached on the ground exhibited superior structural quality as evidenced by measurements of etch pit density, synchrotron white beam X-ray topography and double axis X-ray diffraction. The plans for the flight experiments will be described.

Influence of Containment on the Growth of Silicon-Germanium: A Materials Science Flight Project

NASA Technical Reports Server (NTRS)

Volz, M. P.; Mazuruk, K.; Croell, A.

2012-01-01

A series of Ge(1-x)Si(x) crystal growth experiments are planned to be conducted in the Low Gradient Furnace (LGF) onboard the International Space Station. The primary objective of the research is to determine the influence of containment on the processing-induced defects and impurity incorporation in germanium-silicon alloy crystals. A comparison will be made between crystals grown by the normal and "detached" Bridgman methods and the ground-based float zone technique. Crystals grown without being in contact with a container have superior quality to otherwise similar crystals grown in direct contact with a container, especially with respect to impurity incorporation, formation of dislocations, and residual stress in crystals. "Detached" or "dewetted" Bridgman growth is similar to regular Bridgman growth in that most of the melt is in contact with the crucible wall, but the crystal is separated from the wall by a small gap, typically of the order of 10-100 microns. Long duration reduced gravity is essential to test the proposed theory of detached growth. Detached growth requires the establishment of a meniscus between the crystal and the ampoule wall. The existence of this meniscus depends on the ratio of the strength of gravity to capillary forces. On Earth, this ratio is large and stable detached growth can only be obtained over limited conditions. Crystals grown detached on the ground exhibited superior structural quality as evidenced by measurements of etch pit density, synchrotron white beam X-ray topography and double axis X-ray diffraction. The plans for the flight experiments will be described.

Microgravity

NASA Image and Video Library

2001-01-24

Dr. Alexander Chernov, of the Universities Space Research Association (USRA) and based at Marshall Space Flight Center, is investigating why protein crystals grown in space are, in about 20 percent of cases, better-ordered than those grown on the ground. They are testing the idea that the amount of impurities trapped by space-grown crystals may be different than the amount trapped by crystals grown on Earth because convection is negligible in microgravity. The concentrations or impurities in many space-grown crystals turned out to be several times lower than that in the terrestrial ones, sometimes below the detection limit. The ground-based experiment also showed that the amount of impurities per unit volume of the crystals was usually higher than the amount per unit volume of the solution. This means that a growing crystal actually purifies the solution in its immediate vicinity. Here, an impurity depletion zone is created around apoferritin crystals grown in gel, imitating microgravity conditions.

Growth and microtopographic study of CuInSe{sub 2} single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chauhan, Sanjaysinh M.; Chaki, Sunil, E-mail: sunilchaki@yahoo.co.in; Deshpande, M. P.

2016-05-23

The CuInSe{sub 2} single crystals were grown by chemical vapour transport (CVT) technique using iodine as transporting agent. The elemental composition of the as-grown CuInSe{sub 2} single crystals was determined by energy dispersive analysis of X-ray (EDAX). The unit cell crystal structure and lattice parameters were determined by X-ray diffraction (XRD) technique. The surface microtopographic study of the as-grown CuInSe{sub 2} single crystals surfaces were done to study the defects, growth mechanism, etc. of the CVT grown crystals.

Growth of PBI 2 single crystals from stoichiometric and Pb excess melts

NASA Astrophysics Data System (ADS)

Hayashi, T.; Kinpara, M.; Wang, J. F.; Mimura, K.; Isshiki, M.

2008-01-01

We have successfully grown high-purity and -quality PbI 2 single crystals by the vertical Bridgman method. The rocking curves of four-crystal X-ray diffraction (XRD) show 120 arcsec in full-width at half-maximum (FWHM). The photoluminescence (PL) spectra at 7.8 K show the resolved intensive exciton emission line and the weak DAP emission band. The deep-level emissions are not observed. The measurement of the electrical and radiographic properties show that Leadiodide (PbI 2) single crystal has a resistivity of 5×10 10 Ω cm and imager lag is 8 s, respectively. In order to improve the controllability of crystal growth, PbI 2 single crystals were also grown from a lead (Pb) excess PbI 2 source. The experimental results show very good reproducibility. In addition, the growth models of crystal are proposed, and the growth mechanism is discussed.

Synthesis, growth and characterization of 3-nitroacetanilide—A new organic nonlinear optical crystal by Bridgman technique

NASA Astrophysics Data System (ADS)

Lenin, M.; Ramasamy, P.

2008-10-01

Single crystals of 3-nitroacetanilide, an organic nonlinear optical material has been grown by the Bridgman-Stockbarger method. The single crystal X-ray diffraction (XRD) data revealed the noncentrosymmetric crystal structure, which is an essential criterion for second harmonic generation. The crystalline nature of the grown crystals was confirmed using powder XRD techniques. The functional group of the compound is identified by FTIR spectrum. The thermal stability and its tendency to grow as single crystal in solution and in melt have been identified for the new title compound. The UV-vis spectrum of mNAA shows the lower optical cut off at 400 nm and was transparent in the visible region. The second harmonic generation efficiency was found using Kurtz powder technique. The dielectric constant and dielectric loss of the crystal were measured as a function of frequency and temperature, and the results are discussed.

Solid-state reaction kinetics and optical studies of cadmium doped magnesium hydrogen phosphate crystals

NASA Astrophysics Data System (ADS)

Verma, Madhu; Gupta, Rashmi; Singh, Harjinder; Bamzai, K. K.

2018-04-01

The growth of cadmium doped magnesium hydrogen phosphate was successfully carried out by using room temperature solution technique i.e., gel encapsulation technique. Grown crystals were confirmed by single crystal X-ray diffraction (XRD). The structure of the grown crystal belongs to orthorhombic crystal system and crystallizes in centrosymmetric space group. Kinetics of the decomposition of the grown crystals were studied by non-isothermal analysis. Thermo gravimetric / differential thermo analytical (TG/DTA) studies revealed that the grown crystal is stable upto 119 °C. The various steps involved in the thermal decomposition of the material have been analysed using Horowitz-Metzger, Coats-Redfern and Piloyan-Novikova equations for evaluating various kinetic parameters. The optical studies shows that the grown crystals possess wide transmittance in the visible region and significant optical band gap of 5.5ev with cut off wavelength of 260 nm.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patil, Vidya, E-mail: vidya.patil@ruparel.edu; Patki, Mugdha, E-mail: mugdha.patki@ruparel.edu

Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution.more » Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.« less

Vibrational spectroscopic studies of an organic non-linear optical crystal 8-hydroxyquinolinium picrate

NASA Astrophysics Data System (ADS)

Krishna Kumar, V.; Nagalakshmi, R.

2007-04-01

8-Hydroxyquinolinium picrate (8-HQP) was synthesized by the addition of equimolar quantities of 8-hydroxyquinoline (8-HQ) and picric acid (PA). Single crystals were grown from N, N dimethyl formamide (DMF) by restricted evaporation method at room temperature. The solubility of 8-HQP was determined in different solvents at various temperatures. The structural characterization of the grown crystals was carried out by X-ray diffraction. Vibrational modes were classified on the basis of group theoretical analysis and the spectral bands were compared with those of parent compounds in order to propose a tentative assignment by recording FT-IR, FT-Raman and polarized Raman spectra in different crystal orientations. The crystal possess lower cut-off at 230 nm and good transparency as confirmed by optical transmittance studies.

Growth and characterization of CaFe1-xCoxAsF single crystals by CaAs flux method

NASA Astrophysics Data System (ADS)

Ma, Yonghui; Hu, Kangkang; Ji, Qiucheng; Gao, Bo; Zhang, Hui; Mu, Gang; Huang, Fuqiang; Xie, Xiaoming

2016-10-01

Millimeter sized single crystals of CaFe1-x Cox AsF were grown using a self-flux method. It is found that high-quality single crystals can be grown from three approaches with different initial raw materials. The chemical compositions and crystal structure were characterized carefully. Compared with the undoped parent phase CaFeAsF, the crystal lattice along the c-axis is suppressed by the Co substitution while that along the a-axis expands slightly. Superconductivity with the critical transition Tc as high as 21 K was confirmed by both the resistivity and magnetic susceptibility measurements in the sample with x=0.118. Moreover, it is found that Tc can be enhanced for about 1 K under the very small hydrostatic pressure of 0.22 GPa, which is more quick than that reported in the polycrystalline samples. Our results are a promotion for the physical investigations of 1111 phase iron-pnictide superconductors.

Superheating Suppresses Structural Disorder in Layered BiI3 Semiconductors Grown by the Bridgman Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johns, Paul M.; Sulekar, Soumitra; Yeo, Shinyoung

2016-01-01

The susceptibility of layered structures to stacking faults is a problem in some of the more attractive semiconductor materials for ambient-temperature radiation detectors. In the work presented here, Bridgman-grown BiI3 layered single crystals are investigated to understand and eliminate this structural disorder, which reduces radiation detector performance. The use of superheating gradients has been shown to improve crystal quality in non-layered semiconductor crystals; thus the technique was here explored to improve the growth of BiI3. When investigating the homogeneity of non-superheated crystals, highly geometric void defects were found to populate the bulk of the crystals. Applying a superheating gradient tomore » the melt prior to crystal growth improved structural quality and decreased defect density from the order of 4600 voids per cm3 to 300 voids per cm3. Corresponding moderate improvements to electronic properties also resulted from the superheat gradient method of crystal growth. Comparative measurements through infrared microscopy, etch-pit density, x-ray rocking curves, and sheet resistivity readings show that superheat gradients in BiI3 growth led to higher quality crystals.« less

Crystal growth and dislocation etch pits observation of chalcopyrite CdSiP2

NASA Astrophysics Data System (ADS)

He, Zhiyu; Zhao, Beijun; Zhu, Shifu; Chen, Baojun; Huang, Wei; Lin, Li; Feng, Bo

2018-01-01

CdSiP2 is the only crystal that can offer Non-critical Phase Matching (NCPM) for a 1064 nm pumped optical parametric oscillation (OPO) with idler output in the 6 μm range. In this paper, a large, crack-free CdSiP2 single crystal measuring 18 mm in diameter and 65 mm in length was successfully grown by the Vertical Bridgman method (MVB) with an explosion-proof quartz ampoule. The results of lattice parameters, element composition and IR transmittance of the as-grown crystal characterized by X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS) and Fourier transformation infrared spectrometer (FTIR) showed the as grown crystal crystallized well and the absorption coefficients at 4878 cm-1 and 2500 cm-1 were 0.14 cm-1 and 0.06 cm-1. Moreover, a new etchant composed of Br2, HCl, HNO3, CH3OH and H2O (1:800:800:400:400 in volume ratio) was prepared and the dislocation etch pits on oriented faces of as-grown CdSiP2 crystal were observed for the first time. It is found the etch pits are in rectangular structure on the (1 0 1) face, but in trigonal pyramid structure on (3 1 2) face. According to the quantities of the etch pits, the average densities of dislocation were evaluated to be 2.28 × 105/cm2 and 1.4 × 105/cm2, respectively.

Comparison of the quality of single-crystal diamonds grown on two types of seed substrates by MPCVD

NASA Astrophysics Data System (ADS)

Zhao, Yun; Guo, Yanzhao; Lin, Liangzhen; Zheng, Yuting; Hei, Lifu; Liu, Jinlong; Wei, Junjun; Chen, Liangxian; Li, Chengming

2018-06-01

Microwave plasma chemical vapor deposition (MPCVD) was used to grow single-crystal diamonds on two types of single-crystal diamond seed substrates prepared by high-pressure, high-temperature (HPHT) and chemical vapor deposition (CVD) methods. The quality of diamonds grown on the different seed substrates was compared. Fluorescence characteristics showed that the sectors of the HPHT seed substrates were obviously partitioned. Raman and absorption spectra showed that the CVD seed substrate produced higher-quality crystals with fewer nitrogen impurities. X-ray topography showed that the HPHT seed substrate had obvious growth sector boundaries, inclusions, dislocations, and stacking faults. The polarization characteristics of HPHT seed substrate were obvious, and the stress distribution was not uniform. When etching HPHT and CVD seed substrates using the same parameters, the etching morphology and extent of different growth sectors of the two substrates differed. Although extended defects were inevitably formed at the interface and propagated in the CVD layer, the dislocation density of a 1 mm-thick CVD layer grown on a CVD seed substrate was only half that of a 1 mm-thick CVD layer grown on an HPHT seed substrate. Therefore, the use of CVD seed substrate enabled the growth of a relatively higher-quality CVD single-crystal diamond.

Chemical vapor deposition of high-quality large-sized MoS 2 crystals on silicon dioxide substrates

DOE PAGES

Chen, Jianyi; Tang, Wei; Tian, Bingbing; ...

2016-03-31

Large-sized MoS 2 crystals can be grown on SiO 2/Si substrates via a two-stage chemical vapor deposition method. The maximum size of MoS 2 crystals can be up to about 305 μm. The growth method can be used to grow other transition metal dichalcogenide crystals and lateral heterojunctions. Additionally, the electron mobility of the MoS 2 crystals can reach ≈30 cm 2 V –1 s –1, which is comparable to those of exfoliated flakes.

Chemical Vapor Deposition of High-Quality Large-Sized MoS2 Crystals on Silicon Dioxide Substrates.

PubMed

Chen, Jianyi; Tang, Wei; Tian, Bingbing; Liu, Bo; Zhao, Xiaoxu; Liu, Yanpeng; Ren, Tianhua; Liu, Wei; Geng, Dechao; Jeong, Hu Young; Shin, Hyeon Suk; Zhou, Wu; Loh, Kian Ping

2016-08-01

Large-sized MoS 2 crystals can be grown on SiO 2 /Si substrates via a two-stage chemical vapor deposition method. The maximum size of MoS 2 crystals can be up to about 305 μm. The growth method can be used to grow other transition metal dichalcogenide crystals and lateral heterojunctions. The electron mobility of the MoS 2 crystals can reach ≈30 cm 2 V -1 s -1 , which is comparable to those of exfoliated flakes.

Habit modification of bis-thiourea zinc chloride (ZTC) semi organic crystals by impurities

NASA Astrophysics Data System (ADS)

Ruby Nirmala, L.; Thomas Joseph Prakash, J.

2013-06-01

Single crystals of bis-thiourea zinc chloride (ZTC) doped with metal ion (Li+) possess excellent nonlinear optical properties. These crystals were grown by slow evaporation solution growth technique. The effect of Li+ dopant on the growth and properties of ZTC single crystal were investigated and reported. The grown crystals were crystallized in orthorhombic structure with non-centro symmetric space group Pn21a through the parent compound. The amount of dopant incorporated in the parent crystal was revealed by the inductively coupled plasma (ICP-OES) studies. The FT-IR spectroscopy study was done for finding and confirming the functional groups present in the compound. The UV-Visible spectral study was carried out to find the optical behavior and transparency nature of the grown crystal. TG/DTA measurements and Vickers microhardness measurements were traced to find out the thermal and mechanical stability of the grown crystals respectively. Using Nd:YAG laser, the Second harmonic generation (SHG) for the grown crystals were confirmed.

Habit modification of bis-thiourea zinc chloride (ZTC) semi organic crystals by impurities.

PubMed

Ruby Nirmala, L; Thomas Joseph Prakash, J

2013-06-01

Single crystals of bis-thiourea zinc chloride (ZTC) doped with metal ion (Li(+)) possess excellent nonlinear optical properties. These crystals were grown by slow evaporation solution growth technique. The effect of Li(+) dopant on the growth and properties of ZTC single crystal were investigated and reported. The grown crystals were crystallized in orthorhombic structure with non-centro symmetric space group Pn21a through the parent compound. The amount of dopant incorporated in the parent crystal was revealed by the inductively coupled plasma (ICP-OES) studies. The FT-IR spectroscopy study was done for finding and confirming the functional groups present in the compound. The UV-Visible spectral study was carried out to find the optical behavior and transparency nature of the grown crystal. TG/DTA measurements and Vickers microhardness measurements were traced to find out the thermal and mechanical stability of the grown crystals respectively. Using Nd:YAG laser, the Second harmonic generation (SHG) for the grown crystals were confirmed. Copyright © 2013 Elsevier B.V. All rights reserved.

L-Nitroargininium picrate

NASA Astrophysics Data System (ADS)

Apreyan, R. A.; Fleck, M.; Atanesyan, A. K.; Sukiasyan, R. P.; Petrosyan, A. M.

2015-12-01

L-Nitroargininium picrate has been obtained from an aqueous solution containing equimolar quantities of L-nitroarginine and picric acid by slow evaporation. Single crystal was grown by evaporation method. Crystal structure was determined at room temperature. The salt crystallizes in monoclinic crystal system (space group P21). Vibrational spectra and thermal properties were studied. Second harmonic generation efficiency measured by powder method is found to be four times higher than in L-nitroarginine, which in turn is ten times more efficient than KDP (KH2PO4).

High resolution synchrotron X-radiation diffraction imaging of crystals grown in microgravity and closely related terrestrial crystals

NASA Technical Reports Server (NTRS)

Steiner, Bruce; Dobbyn, Ronald C.; Black, David; Burdette, Harold; Kuriyama, Masao; Fripp, Archibald; Simchik, Richard

1991-01-01

Irregularities in three crystals grown in space and in four terrestrial crystals grown under otherwise comparable conditions have been observed in high resolution diffraction imaging. The images provide important new clues to the nature and origins of irregularities in each crystal. For two of the materials, mercuric iodide and lead tin telluride, more than one phase (an array of non-diffracting inclusions) was observed in terrestrial samples; but the formation of these multiple phases appears to have been suppressed in directly comparable crystals grown in microgravity. The terrestrial seed crystal of triglycine sulfate displayed an unexpected layered structure, which propagated during directly comparable space growth. Terrestrial Bridgman regrowth of gallium arsenide revealed a mesoscopic structure substantially different from that of the original Czochralski material. A directly comparable crystal is to be grown shortly in space.

Growth, structural, optical, thermal and mechanical properties of cytosinium hydrogen selenite: A novel nonlinear optical single crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaikumar, P.; Sathiskumar, S.; Balakrishnan, T., E-mail: balacrystalgrowth@gmail.com

Highlights: • Growth of bulk single crystals of cytosinium hydrogen selenite (CHS) is reported. • Dielectric constant of CHS is measured as a function of Frequency and temperature. • Lower cut off value of UV–vis-NIR spectrum of CHS crystal is observed at 210 nm. • Meyer’s index value of CHS crystal calculated identifies it as a soft material. • Powder SHG efficiency of CHS is about 1.5 times that of KDP crystal. - Abstract: A novel nonlinear optical single crystal of cytosinium hydrogen selenite was grown from aqueous solution of cytosinium hydrogen selenite by slow solvent evaporation method at roommore » temperature. The structural properties of grown crystal have been studied by single crystal and powder X-ray diffraction analysis. Presence of various functional groups was identified from Fourier transform infrared spectroscopy. The optical transmittance and absorbance spectra were recorded by UV–vis-NIR spectrometer and the grown crystal possesses good transparency in the entire visible region. The dielectric constant and dielectric loss of the crystal were calculated as a function of frequency at different temperatures. The mechanical strength of the cytosinium hydrogen selenite crystal was estimated using Vicker’s microhardness tester. Etch patterns of the cytosinium hydrogen selenite crystal were obtained using distilled water as etchant for different etching time. Second harmonic generation efficiency tested using Nd:YAG laser is about 1.5 times that of KDP.« less

Single crystal growth of spin-ladder compound La8Cu7O19 by the travelling-solvent floating zone method

NASA Astrophysics Data System (ADS)

Mohan, A.; Singh, S.; Partzsch, S.; Zwiebler, M.; Geck, J.; Wurmehl, S.; Büchner, B.; Hess, C.

2016-08-01

Large single crystals of La8Cu7O19 have been grown using the travelling-solvent floating zone method. A rather high oxygen pressure of 9 bar in the growth chamber and a slow growth speed of 0.5 mm/h were among the most important parameters in stabilizing the growth of this incongruently melting compound. Interestingly, a novel growth scenario has been witnessed. The crystal structure of the grown La8Cu7O19 crystal has been analyzed using single crystal diffractometry to extract important structural parameters of this compound. We find that La8Cu7O19 crystallizes in a monoclinic structure with space group C 2 / c and has the lattice parameters a ≈ 13.83 Å, b ≈ 3.75 Å, c ≈ 34.59 Å, and β ≈ 99.33 °, in good agreement with the data obtained on polycrystalline samples in the literature. The magnetization shows a highly anisotropic behavior, and an anomaly at T ≈103 K.

Investigation of Artificial Forced Cooling in the Bridgman Crystal Growth of Cadmium Zinc Telluride

NASA Astrophysics Data System (ADS)

Liu, Juncheng; Li, Jiao; Zhang, Guodong; Li, Changxing; Lennon, Craig; Sivananthan, Siva

2007-08-01

The effects of artificial forced cooling on the solid liquid interface and on solute segregation were investigated by modeling the vertical Bridgman method for the single-crystal growth of CdZnTe, taking into consideration effects such as increasing the axial outward heat flux from the crucible bottom, the radial outward heat flux from the crucible wall, and the carbon film thickness on the crucible inner wall. Axial artificially forced cooling noticeably increases convection and the temperature gradient in the melt next to the solid liquid interface, and substantially reduces interface concavity at the initial solidification stage. Interface concavity increases a little when the solidification proceeds further, however. Axial artificially forced cooling reduces radial solute segregation of the initial segment of the grown crystal and slightly increases the solute iso-concentration segment. Radial artificially forced cooling enhances melt convection substantially, affects solid liquid interface concavity only slightly, and hardly affects solute segregation in the grown crystal. Doubling the carbon film thickness weakens convection of the melt in front of the interface, substantially increases interface concavity, and hardly affects solute segregation in the grown crystal.

RNi2B2C (R = Ho, Dy, Tb and Pr) single crystals grown by the cold copper crucible method

NASA Astrophysics Data System (ADS)

Durán, A.; Munoz, E.; Bernès, S.; Escudero, R.

2000-08-01

Single crystals of RNi2B2C (R = Ho, Dy, Tb, Pr) have been grown on cold copper crucibles in a high-frequency induction furnace. As a result, shiny metallic and brittle platelike single crystals were obtained. They were examined by x-ray and scanning electron microscopy with WDX/EDX for local composition analysis and show a very good crystallographic structure and compositions. Resistivity and dc magnetic measurements were performed to study superconducting and magnetic properties. Besides known electronic properties of the RNi2B2C family, we report for the first time results for PrNi2B2C single crystals successfully obtained by this technique.

Homogeneity of CdZnTe detectors

NASA Astrophysics Data System (ADS)

Hermon, H.; Schieber, M.; James, R. B.; Lund, J.; Antolak, A. J.; Morse, D. H.; Kolesnikov, N. N. P.; Ivanov, Y. N.; Goorsky, M. S.; Yoon, H.; Toney, J.; Schlesinger, T. E.

1998-02-01

We describe the current state of nuclear radiation detectors produced from single crystals of Cd 1- xZn xTe(CZT), with 0.04 < x < 0.4, grown by the vertical high pressure Bridgman (VHPB) method. The crystals investigated were grown commercially both in the USA and at the Institute of Solid State Physics, Chernogolska, Russia. The CZT was evaluated by Sandia National Laboratories and the UCLA and CMU groups using proton-induced X-ray emission (PIXE), X-ray diffraction (XRD), photoluminescence (PL), infrared (IR) transmission microscopy, leakage current measurements and response to nuclear radiation. We discuss the homogeneity of the various CZT crystals based on the results from these measurement techniques.

Growth and lasing of single crystal YAG fibers with different Ho3+ concentrations

NASA Astrophysics Data System (ADS)

Bera, Subhabrata; Nie, Craig D.; Soskind, Michael G.; Li, Yuan; Harrington, James A.; Johnson, Eric G.

2018-01-01

A method to grow single crystal (SC) yttrium aluminum garnet (YAG) fibers with varied rare-earth ion dopant concentration has been proposed. Crystalline holmium aluminum garnet (HoAG), prepared via sol-gel process, was dip-coated on to previously grown SC YAG fibers. The HoAG coated SC YAG fiber preforms were re-grown to a smaller diameter using the laser heated pedestal growth (LHPG) technique. The final dopant concentration of the re-grown SC fiber was varied by changing the number of HoAG coatings on the preform. 120 μm diameter SC Ho:YAG fibers with four different dopant concentrations were grown. Lasing was demonstrated at 2.09 μm for these fibers. A maximum of 58.5% optical-to-optical slope efficiency was obtained.

Effects of Ca/Sr ratio control on optical and scintillation properties of Eu-doped Li(Ca,Sr)AlF6 single crystals

NASA Astrophysics Data System (ADS)

Yokota, Yuui; Tanaka, Chieko; Kurosawa, Shunsuke; Yamaji, Akihiro; Ohashi, Yuji; Kamada, Kei; Nikl, Martin; Yoshikawa, Akira

2018-05-01

Eu-doped Li(Ca,Sr)AlF6 [Eu:LiCSAF] single crystals with various Ca/Sr ratios were grown by the micro-pulling-down method, and their optical and scintillation properties were investigated to reveal the effects of Ca/Sr ratio on optical and scintillation properties of the Eu:LiCSAF single crystals. The Li(Ca1-x-ySrxEuy)AlF6 single crystals could be grown in 0 ≤ x ≤ 0.1, 0.5 ≤ x ≤ 1.0 and y = 0.02 while the Eu:LiCSAF crystals with x = 0.2, 0.25 and 0.4 included two colquiriite-type phases with different lattice parameters. The Li(Ca1-x-ySrxEuy)AlF6 single crystal with x = 0.25 and y = 0.02 showed the highest light yield under neutron irradiation.

High quality self-separated GaN crystal grown on a novel nanoporous template by HVPE.

PubMed

Huo, Qin; Shao, Yongliang; Wu, Yongzhong; Zhang, Baoguo; Hu, Haixiao; Hao, Xiaopeng

2018-02-16

In this study, a novel nanoporous template was obtained by a two-step etching process from MOCVD-GaN/Al 2 O 3 (MGA) with electrochemical etching sequentially followed by chemical wet etching. The twice-etched MOCVD-GaN/Al 2 O 3 (TEMGA) templates were utilized to grow GaN crystals by hydride vapor phase epitaxy (HVPE) method. The GaN crystals were separated spontaneously from the TEMGA template with the assistance of voids formed by the etched nanopores. Several techniques were utilized to characterize the quality of the free-standing GaN crystals obtained from the TEMGA template. Results showed that the quality of the as-obtained GaN crystals was improved obviously compared with those grown on the MGA. This convenient technique can be applied to grow high-quality free-standing GaN crystals.

Comparative Analysis of Thaumatin Crystals Grown on Earth and in Microgravity. Experiment 23

NASA Technical Reports Server (NTRS)

Ng, Joseph D.; Lorber, Bernard; Giege, Richard; Koszelak, Stanley; Day, John; Greenwood, Aaron; McPherson, Alexander

1998-01-01

The protein thaumatin was studied as a model macromolecule for crystallization in microgravity environment experiments conducted on two U.S. Space Shuttle missions (second United States Microgravity Laboratory (USML-2) and Life and Microgravity Spacelab (LMS)). In this investigation we evaluated and compared the quality of space- and Earth-grown thaumatin crystals using x-ray diffraction analysis and characterized them according to crystal size, diffraction resolution limit, and mosaicity. Two different approaches for growing thaumatin crystals in the microgravity environment, dialysis and liquid-liquid diffusion, were employed as a joint experiment by our two investigative teams. Thaumatin crystals grown under a microgravity environment were generally larger in volume with fewer total crystals. They diffracted to significantly higher resolution and with improved diffraction properties as judged by relative Wilson plots. The mosaicity for space-grown crystals was significantly less than for those grown on Earth. Increasing concentrations of protein in the crystallization chambers under microgravity lead to larger crystals. The data presented here lend further support to the idea that protein crystals of improved quality can be obtained in a microgravity environment.

Temperature cycling vapor deposition HgI.sub.2 crystal growth

DOEpatents

Schieber, Michael M.; Beinglass, Israel; Dishon, Giora

1977-01-01

A method and horizontal furnace for vapor phase growth of HgI.sub.2 crystals which utilizes controlled axial and radial airflow to maintain the desired temperature gradients. The ampoule containing the source material is rotated while axial and radial air tubes are moved in opposite directions during crystal growth to maintain a desired distance and associated temperature gradient with respect to the growing crystal, whereby the crystal interface can advance in all directions, i.e., radial and axial according to the crystallographic structure of the crystal. Crystals grown by this method are particularly applicable for use as room-temperature nuclear radiation detectors.

Study on structural, morphological, optical and thermal properties of guanidine carbonate doped nickel sulfate hexahydrate crystal.

PubMed

Silambarasan, A; Rajesh, P; Ramasamy, P

2015-01-05

The single crystal of guanidine carbonate doped nickel sulfate hexahydrate was grown from solution for ultraviolet filters. The single crystal XRD confirms that the grown single crystal belongs to the tetragonal system with the space group of P4₁2₁2. The crystallinity of the grown crystal was estimated by powder X-ray diffraction studies. The optical transmission and thermal stability of as-grown guanidine carbonate doped nickel sulfate single crystals have been studied. The optical transmission spectrum demonstrates the characteristics of ultraviolet filters. The TG/DTA studies confirm the thermal properties of grown crystals. Thermo-gravimetric analysis showed that the dehydration temperature of the guanidine carbonate doped nickel sulfate crystal is about 100 °C, which is much higher than that of pure nickel sulfate hexahydrate (NSH) crystals which is 72 °C. The growth behaviors and dislocation density were detected under the high resolution XRD and etching studies respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

Linear, non-linear and thermal properties of single crystal of LHMHCl

NASA Astrophysics Data System (ADS)

Kulshrestha, Shobha; Shrivastava, A. K.

2018-05-01

The single crystal of amino acid of L-histidine monohydrochloride was grown by slow evaporation technique at room temperature. High optical quality and appropriate size of crystals were grown under optimized growth conditions. The grown crystals were transparent. Crystals are characterized with different characterizations such as Solubility test, UV-Visible, optical band gap (Eg). With the help of optical data to be calculate absorption coefficient (α), extinction coefficient (k), refractive index (n), dielectric constant (ɛ). These optical constants are shows favorable conditions for photonics devices. Second harmonic generation (NLO) test show the green light emission which is confirm that crystal have properties for laser application. Thermal stability of grown crystal is confirmed by TG/DTA.

Growth and characterization of divalent transition metal ions doped zinc hydrogen phosphate single crystals

NASA Astrophysics Data System (ADS)

D'Souza, Delma; Jagannatha, N.; Nagaraja, K. P.; Rohith, P. S.; Pradeepkumar, K. V.

2018-05-01

Zinc hydrogen phosphate (ZnHP) single crystal co-doped with divalent transition metal ions Cobalt (Co2+) and Cadmium (Cd2+) is grown by gel technique in silica hydro gel media. The presence of Co2+ and Cd2+ dopants in the ZnHP crystal was confirmed by Energy Dispersive X-ray Analysis (EDAX).FTIR spectra of the grown crystal depict the stretching and bending vibration of PO4 units, water of crystallization and metal-oxygen bonds. Powder XRD analysis reveals that the grown crystal belongs to monoclinic system with spacegroup P 21. The thermal stability of the grown crystal is rectified from TG-DSC studies.

Crystallization and preliminary X-ray diffraction study of thermostable RNase HIII from Bacillus stearothermophilus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chon, Hyongi; Matsumura, Hiroyoshi; Koga, Yuichi

2005-03-01

A thermostable ribonuclease HIII from B. stearothermophilus (Bst RNase HIII) was crystallized and preliminary crystallographic studies were performed. Plate-like overlapping polycrystals were grown by the sitting-drop vapour-diffusion method at 283 K.

On thermal conditions and properties of thallium bromide single crystals grown by the Electro Dynamic Gradient method

NASA Astrophysics Data System (ADS)

Zheng, Zhiping; Yu, Yongtao; Gong, Shuping; Fu, Qiuyun; Zhou, Dongxiang

2013-05-01

The Electro Dynamic Gradient (EDG) method has been proved to be a feasible way to grow TlBr crystals in our previous work. In this research, the influence of thermal conditions such as cooling rate during growth process on the crystal performance was investigated. Crystals of approximately 12 mm diameter were obtained by the EDG method at different cooling rates during the growth process, and the quality of the crystals was routinely evaluated by X-ray diffraction (XRD), infrared (IR) and ultraviolet (UV) transmission, I-V measurement and energy response spectrum. The results proved that thermal conditions during growth had a profound influence on the characteristics of the crystals.

High Resolution X-Ray Diffraction of Macromolecules with Synchrotron Radiation

NASA Technical Reports Server (NTRS)

Stojanoff, Vivian; Boggon, Titus; Helliwell, John R.; Judge, Russell; Olczak, Alex; Snell, Edward H.; Siddons, D. Peter; Rose, M. Franklin (Technical Monitor)

2000-01-01

We recently combined synchrotron-based monochromatic X-ray diffraction topography methods with triple axis diffractometry and rocking curve measurements: high resolution X-ray diffraction imaging techniques, to better understand the quality of protein crystals. We discuss these methods in the light of results obtained on crystals grown under different conditions. These non destructive techniques are powerful tools in the characterization of the protein crystals and ultimately will allow to improve, develop, and understand protein crystal growth. High resolution X-ray diffraction imaging methods will be discussed in detail in light of recent results obtained on Hen Egg White Lysozyme crystals and other proteins.

Control of optical properties of YAG crystals by thermal annealing

NASA Astrophysics Data System (ADS)

Tkachenko, S.; Arhipov, P.; Gerasymov, I.; Kurtsev, D.; Vasyukov, S.; Nesterkina, V.; Shiran, N.; Mateichenko, P.; Sidletskiy, O.

2018-02-01

Optical properties of YAG crystals grown and annealed under different atmosphere conditions have been compared. Simultaneously we have registered the surface composition of crystals and content of basic admixtures in the crystals grown under the reducing conditions. Unlike YAG grown under weakly oxidizing conditions in Ir crucibles and bleached under oxidizing annealing, YAGMo crystals grown in Mo crucibles under reducing Ar + CO atmosphere can be bleached by both oxidizing and reducing thermal annealing. The bleaching of YAGMo is not reversed by further annealing under any available conditions. Mechanisms of this phenomenon have been discussed, including a possible role of admixtures in elimination of color centers in YAG grown under the reducing conditions.

Study on growth techniques and macro defects of large-size Nd:YAG laser crystal

NASA Astrophysics Data System (ADS)

Quan, Jiliang; Yang, Xin; Yang, Mingming; Ma, Decai; Huang, Jinqiang; Zhu, Yunzhong; Wang, Biao

2018-02-01

Large-size neodymium-doped yttrium aluminum garnet (Nd:YAG) single crystals were grown by the Czochralski method. The extinction ratio and wavefront distortion of the crystal were tested to determine the optical homogeneity. Moreover, under different growth conditions, the macro defects of inclusion, striations, and cracking in the as-grown Nd:YAG crystals were analyzed. Specifically, the inclusion defects were characterized using scanning electron microscopy and energy dispersive spectroscopy. The stresses of growth striations and cracking were studied via a parallel plane polariscope. These results demonstrate that improper growth parameters and temperature fields can enhance defects significantly. Thus, by adjusting the growth parameters and optimizing the thermal environment, high-optical-quality Nd:YAG crystals with a diameter of 80 mm and a total length of 400 mm have been obtained successfully.

Growth and characterization of Bis(L-threonine) copper (II) monohydrate single crystals: A semiorganic second order nonlinear optical material

NASA Astrophysics Data System (ADS)

Subhashini, R.; Sathya, D.; Sivashankar, V.; Latha Mageshwari, P. S.; Arjunan, S.

2016-12-01

Highly transparent solitary nonlinear semiorganic optical material Bis(L-threonine) copper (II) monohydrate [BLTCM], was synthesized by a conventional slow evaporation solution growth technique. The grown crystals were subjected to structural, optical, electrical, thermal, mechanical, SHG and Laser damage threshold studies. Single crystal XRD shows that the material crystallizes in monoclinic system with noncentrosymmetric space group P21. FT-IR and FT-RAMAN analyses confirm the various functional groups present in the grown crystal. The transparency range of BLTCM was determined by UV-vis-NIR studies and various optical constants such as extinction coefficient (K), refractive index, optical conductivity and electric susceptibility with real and imaginary parts of dielectric constant were calculated using the transmittance data which have applications in optoelectronic devices. Dielectric studies of the crystal were carried out at different frequencies and temperatures to analyze the electrical properties. TGA and DSC analyses were performed to study the thermal behaviour of the sample. The hardness stability of the grown specimen was investigated by Vickers microhardness test. The output intensity of second harmonic generation was confirmed using the Kurtz and Perry powder method. The laser induced surface damage threshold of the crystal was measured using Nd:YAG laser.

Influence of bis-thiourea nickel nitrate on the structural, optical, electrical, thermal and mechanical behavior of a KDP single crystal for NLO applications

NASA Astrophysics Data System (ADS)

Rasal, Y. B.; Shaikh, R. N.; Shirsat, M. D.; Kalainathan, S.; Hussaini, S. S.

2017-03-01

A single crystal of bis-thiourea nickel nitrate (BTNN) doped potassium dihydrogen phosphate (KDP) has been grown from solution at room temperature by a slow evaporation technique. The cell parameters of the grown crystals were determined using single crystal x-ray diffraction analysis. The different functional groups of the grown crystal were confirmed using Fourier transform infrared analysis. The improved optical parameters of the grown crystal have been evaluated in the range of 200-900 nm using UV-visible spectral analysis. The grown crystal was transparent in the entire visible region and the band gap value was found to be 4.96 eV. The influence of BTNN on the third order nonlinear optical properties of KDP crystal has been investigated by means of the Z-scan technique. The second harmonic generation (SHG) efficiency of grown crystal measured using a Nd-YAG laser is 1.98 times higher than that of pure KDP. The third order nonlinear optical susceptibility (χ 3) and nonlinear absorption coefficient (β) of BTNN doped KDP crystal is found to be 1.77  ×  10-5 esu and 5.57  ×  10-6 cm W-1 respectively. The laser damage threshold (LDT) energy for the grown crystal has been measured by using a Q-switched Nd:YAG laser source. The bis-thiourea nickel nitrate shows authoritative impact on the dielectric properties of doped crystal. The influence of bis-thiourea nickel nitrate on the mechanical behavior of KDP crystal has been investigated using Vickers microhardness intender. The thermal behavior of BTNN doped KDP crystal has been analyzed by TGA/DTA analysis.

The Morse code effect: A crystal-crystal transformation observed in gel-grown lead (II) oxalate crystals

NASA Astrophysics Data System (ADS)

Lisgarten, J. N.; Marks, J. A.

2018-05-01

This paper reports on an unusual crystal-crystal transformation phenomenon, which we have called the Morse Code Effect, based on the change in appearance of lead(II) oxalate crystals grown in agarose gels.

Crystal growth and characterization of third order nonlinear optical piperazinium bis(4-hydroxybenzenesulphonate) (P4HBS) single crystal

NASA Astrophysics Data System (ADS)

Pichan, Karuppasamy; Muthu, Senthil Pandian; Perumalsamy, Ramasamy

2017-09-01

The organic single crystal of piperazinium bis(4-hydroxybenzenesulphonate) (P4HBS) was grown by slow evaporation solution technique (SEST) at room temperature. The lattice parameters of the grown crystal were confirmed by single crystal X-ray diffraction analysis. Functional groups of P4HBS crystal were confirmed by FTIR spectrum analysis. The optical quality of the grown crystal was identified by the UV-Vis NIR spectrum analysis. The grown crystal has good optical transmittance in the range of 410-1100 nm. In photoluminescence spectrum, sharp emission peaks are observed, which indicates the ultraviolet (UV) emission. The photoconductivity study reveals that the grown crystal has negative photoconductive nature. The thermal behaviour of the P4HBS crystal was investigated by thermogravimetric and differential thermal analysis (TG-DTA). The mechanical stability of grown crystal was analyzed and the indentation size effect (ISE) was explained by Hays-Kendall's (HK) approach and proportional specimen resistance model (PSRM). Chemical etching study was carried out and the etch pit density (EPD) was calculated. The dielectric constant (ε‧) and dielectric loss (tan δ) as a function of frequency were measured for the grown crystal. The solid state parameters such as valence electron, plasma energy, Penn gap and Fermi energy were evaluated theoretically for the P4HBS using the empirical relation. The estimated values are used to calculate the electronic polarizability. The third-order nonlinear optical properties such as nonlinear refractive index (n2), absorption co-efficient (β) and susceptibility (χ(3)) were studied by Z-scan technique at 632.8 nm using He-Ne laser.

Growth of propyl-p-hydroxybenzoate single crystals and its characterizations

NASA Astrophysics Data System (ADS)

Karunagaran, N.; Ramasamy, P.

2012-06-01

Single crystals of Propyl-p-hydroxybenzoate (PHB) crystals have been grown by slow evaporation solution technique (SEST) using methanol as a solvent. The PHB single crystal of dimension up to 27×16×8 mm3 has been grown in a period of 18 days at room temperature. The optical transparency of the grown PHB crystal has been measured on (212) plane by UV-Vis-NIR spectrophotometer. The crystal has 60% of transparency in the entire visible region. The thermo gravimetric analysis (TG) and differential thermal analysis (DTA) studies reveal that the crystal is thermally stable up to 99°C. The mechanical strength of the grown PHB crystal is measured using Vickers microhardness tester. The chemical etching studies were carried out on (212) plane using methanol etchant. The laser damage threshold of PHB crystal is 1.3 GW/cm2. The dielectric properties have been investigated. The birefringence value is found to be 0.10148 at the wavelength of 504 nm. The refractive index of grown PHB single crystal is 1.6753.

Zeolite Crystal Growth (ZCG) Flight on USML-2

NASA Technical Reports Server (NTRS)

Sacco, Albert, Jr.; Bac, Nurcan; Warzywoda, Juliusz; Guray, Ipek; Marceau, Michelle; Sacco, Teran L.; Whalen, Leah M.

1997-01-01

The extensive use of zeolites and their impact on the world's economy has resulted in many efforts to characterize their structure, and improve the knowledge base for nucleation and growth of these crystals. The zeolite crystal growth (ZCG) experiment on USML-2 aimed to enhance the understanding of nucleation and growth of zeolite crystals, while attempting to provide a means of controlling the defect concentration in microgravity. Zeolites A, X, Beta, and Silicalite were grown during the 16 day - USML-2 mission. The solutions where the nucleation event was controlled yielded larger and more uniform crystals of better morphology and purity than their terrestrial/control counterparts. The external surfaces of zeolite A, X, and Silicalite crystals grown in microgravity were smoother (lower surface roughness) than their terrestrial controls. Catalytic studies with zeolite Beta indicate that crystals grown in space exhibit a lower number of Lewis acid sites located in micropores. This suggests fewer structural defects for crystals grown in microgravity. Transmission electron micrographs (TEM) of zeolite Beta crystals also show that crystals grown in microgravity were free of line defects while terrestrial/controls had substantial defects.

Thermal, mechanical, optical and conductivity studies of a novel NLO active L-phenylalanine L-phenylalaninium dihydrogenphosphate single crystal

NASA Astrophysics Data System (ADS)

Sujatha, T.; Cyrac Peter, A.; Vimalan, M.; Merline Shyla, J.; Madhavan, J.

2010-08-01

An efficient, novel, semi-organic, nonlinear optical (NLO) material L-phenylalanine L-phenylalaninium dihydrogenphosphate (LPADHP), single crystal of dimension 11×5×2 mm 3, has been grown by the slow evaporation solution growth technique. Single crystal X-ray diffraction studies confirm that the grown crystal belongs to monoclinic system with the space group P2 1. The functional groups present in the crystal were confirmed by the Fourier transform infrared technique. Optical absorption spectrum shows that the material possesses very low absorption in the entire visible region. Thermal analysis confirmed that the crystal is thermally stable up to 161 °C. The frequency dependent dielectric properties of the grown crystal were studied for various temperatures. The second harmonic generation (SHG) efficiency of the grown crystal is 1.2 times greater than that of the potassium dihydrogenphosphate (KDP) single crystal. The laser induced surface damage threshold for the grown crystal was found to be 6.3 GW cm -2 with Nd:YAG laser assembly AC and DC conductivity and photoconductivity experiments are also carried out and the results are discussed.

Growth and characterization of benzyl 4-hydroxybenzoate single crystal by vertical Bridgman technique for optical applications

NASA Astrophysics Data System (ADS)

Solanki, S. Siva Bala; Rajesh, N. P.; Suthan, T.

2018-07-01

The benzyl 4-hydroxybenzoate single crystal has been grown by vertical Bridgman technique. The grown crystal was confirmed by single crystal X-ray diffraction studies. The presence of functional groups in the crystal was confirmed by Fourier transform infrared (FTIR) spectral studies. The thermal behaviour of the grown crystal was analyzed by thermogravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetric (DSC) studies. Optical behaviour of the grown benzyl 4-hydroxybenzoate crystal was studied by UV-Vis-NIR spectral analysis. Fluorescence spectrum shows near violet light emission. The second harmonic generation behaviour of benzyl 4-hydroxybenzoate was analyzed. The laser damage threshold value of benzyl 4-hydroxybenzoate was measured as 2.16 GW/cm2. The dielectric measurements of benzyl 4-hydroxybenzoate crystal were carried out with different frequencies 1 kHz to 1 MHz versus different temperatures ranging from 313 to 353 K. Photoconductivity study shows that the grown benzyl 4-hydroxybenzoate crystal belongs to negative photoconductivity property. The mechanical strength of the crystal was calculated by Vickers microhardness study.

Structural, thermal, laser damage, photoconductivity, NLO and mechanical properties of modified vertical Bridgman method grown AgGa0.5In0.5Se2 single crystal

NASA Astrophysics Data System (ADS)

Vijayakumar, P.; Ramasamy, P.

2016-08-01

AgGa0.5In0.5Se2 single crystal was grown using modified vertical Bridgman method. The structural perfection of the AgGa0.5In0.5Se2 single crystal has been analyzed by high-resolution X-ray diffraction rocking curve measurements. The structural and compositional uniformities of AgGa0.5In0.5Se2 were studied using Raman scattering spectroscopy at room temperature. The FWHM of the Γ1 (W1) and Γ5L (Γ15) measured at different regions of the crystal confirms that the composition throughout its length is fairly uniform. Thermal properties of the as-grown crystal, including specific heat, thermal diffusivity and thermal conductivity have been investigated. The multiple shot surface laser damage threshold value was measured using Nd:YAG laser. Photoconductivity measurements with different temperatures have confirmed the positive photoconducting behavior. Second harmonic generation (SHG) on powder samples has been measured using the Kurtz and Perry technique and the results display that AgGa0.5In0.5Se2 is a phase-matchable NLO material. The hardness behavior has been measured using Vickers micro hardness measurement and the indentation size effect has been observed. The classical Meyer's law, propositional resistance model and modified propositional resistance model have been used to analyse the micro hardness behavior.

Crystal growth and optical properties of 4-aminobenzophenone (ABP)

NASA Astrophysics Data System (ADS)

Li, Zhengdong; Wu, Baichang; Su, Genbo; Huang, Gongfan

1997-02-01

Bulk crystals of 4-aminobenzophenone (ABP) were grown from organic solution. The crystal structure was determined by X-ray analysis. The refractive indices were determined by the method of prism minimum deviation. Some effective nonlinear-optical coefficients deff were measured. A blue second-harmonic emission with wavelengths of 433 and 460 nm were observed during laser diode pumping.

Growth, optical, ICP and thermal studies of nonlinear optical single crystal: Sodium acid phthalate (NaAP)

NASA Astrophysics Data System (ADS)

Mahadevan, M.; Arivanandhan, M.; Elangovan, K.; Anandan, P.; Ramachandran, K.

2017-07-01

Good quality single crystals of sodium acid phthalate (NaAP) were grown by slow evaporation technique. Single crystal X-ray diffraction study of the grown crystal reveals that the crystal belongs to orthorhombic system with space group B2ab. Fourier transform infrared spectrum confirms the presence of the functional groups of the grown material. Inductively coupled plasma emission spectroscopy analysis is used to confirm the presence of Na element in the sample. Thermal analysis of the NaAP crystal shows that the crystal is stable up to 140°C. Optical transmittance of the grown crystal was recorded in the wavelength range from 200 and 800 nm using UV-Vis-NIR spectrophotometer. The second harmonic generation of NaAP was analysed using Kurtz powder technique.

Screening and structural elucidation of the zwitterionic cocrystal o-picolinic acid with p-nitro aniline

NASA Astrophysics Data System (ADS)

Mekala, R.; Jagdish, P.; Mathammal, R.; Sangeetha, K.

2017-04-01

The cocrystal was screened by solvent drop grinding method and the crystals were grown by slow evaporation method at ambient conditions. The cocrystal formation of o-picolinic acid with p-nitro aniline was initially analysed by powder X-ray diffraction. Further the structural properties of the grown crystal were confirmed by the single X-ray diffraction which indicates that the cocrystal were connected by the strong N+sbnd H-⋯O hydrogen bond interaction. The cell parameters of the grown crystal were a = 14.2144(5) Å, b = 5.7558(2) Å, c = 16.0539(6) Å. The functional groups were identified using Fourier transform infrared and Raman spectral analysis. The excitation and emission state of the sample was analysed by the UV-Visible and Fluorescence studies. The red emission was observed from the Fluorescence studies. NMR studies revealed the chemical shift of the cocrystal. Thermal stability and its melting behaviour were studied by TGA and DSC analytical techniques. Electrical behaviour was studied using the dielectric studies. The intermolecular charge transfer within the molecule were analysed using HOMO- LUMO plots.

Crystalline perfection and optical studies of L-Histidinium dihydrogen phosphate orthophosphoric acid (LHDP) single crystals

NASA Astrophysics Data System (ADS)

Ittyachan, Reena; Arunkumar, A.; Bhagavannarayana, G.

2015-10-01

Single crystals of L-Histidinium dihydrogenphosphate orthophosphoric acid (LHDP) were grown by slow evaporation solution growth technique. The grown crystals were confirmed by single crystal X-ray diffraction techniques. The HRXRD rocking curve measurements revealed the crystalline perfection of grown crystal and the absence of structural grain boundaries. The lower optical cut-off wavelength for this crystal was observed at 240 nm. The third order nonlinear refractive index (n2), nonlinear absorption coefficient (β) and susceptibility (χ(3)) were calculated by Z-scan studies using Nd: YAG laser as a source. The single shot laser damage threshold of grown crystal was measured to be 6.286 GW/cm2 using Nd: YAG laser.

Solution-grown crystals for neutron radiation detectors, and methods of solution growth

DOEpatents

Zaitseva, Natalia P; Hull, Giulia; Cherepy, Nerine J; Payne, Stephen A; Stoeffl, Wolfgang

2012-06-26

A method according to one embodiment includes growing an organic crystal from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source. A system according to one embodiment includes an organic crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source; and a photodetector for detecting the signal response of the organic crystal. A method according to another embodiment includes growing an organic crystal from solution, the organic crystal being large enough to exhibit a detectable signal response signature for neutrons from a radioactive source. An organic crystal according to another embodiment includes an organic crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source, wherein the organic crystal has a length of greater than about 1 mm in one dimension.

3D Micro-topography of Transferred Laboratory and Natural Ice Crystal Surfaces Imaged by Cryo and Environmental Scanning Electron Microscopy

NASA Astrophysics Data System (ADS)

Magee, N. B.; Boaggio, K.; Bancroft, L.; Bandamede, M.

2015-12-01

Recent work has highlighted micro-scale roughness on the surfaces of ice crystals grown and imaged in-situ within the chambers of environmental scanning electron microscopes (ESEM). These observations appear to align with theoretical and satellite observations that suggest a prevalence of rough ice in cirrus clouds. However, the atmospheric application of the lab observations are indeterminate because the observations have been based only on crystals grown on substrates and in pure-water vapor environments. In this work, we present details and results from the development of a transfer technique which allows natural and lab-grown ice and snow crystals to be captured, preserved, and transferred into the ESEM for 3D imaging. Ice crystals were gathered from 1) natural snow, 2) a balloon-borne cirrus particle capture device, and 3) lab-grown ice crystals from a diffusion chamber. Ice crystals were captured in a pre-conditioned small-volume (~1 cm3) cryo-containment cell. The cell was then sealed closed and transferred to a specially-designed cryogenic dewer (filled with liquid nitrogen or crushed dry ice) for transport to a new Hitachi Field Emission, Variable Pressure SEM (SU-5000). The cryo-cell was then removed from the dewer and quickly placed onto the pre-conditioned cryo transfer stage attached to the ESEM (Quorum 3010T). Quantitative 3D topographical digital elevation models of ice surfaces are reported from SEM for the first time, including a variety of objective measures of statistical surface roughness. The surfaces of the transported crystals clearly exhibit signatures of mesoscopic roughening that are similar to examples of roughness seen in ESEM-grown crystals. For most transported crystals, the habits and crystal edges are more intricate that those observed for ice grown directly on substrates within the ESEM chamber. Portions of some crystals do appear smooth even at magnification greater than 1000x, a rare observation in our ESEM-grown crystals. The transported crystals hint at some significant differences in roughness morphology, but they do provide evidence that crystals grown in air/water mixtures and with minimal substrate influence also exhibit mesoscopic roughness with similarity to that observed in ESEM-grown crystals.

1. Innovative Relaxor-Based PiezoCrystals: Phase Diagrams, Crystal Growth, Domain Structures and Electric Properties. 2. Piezo- and Ferroelectric Materials Based on Morphotropic Phase Boundary Synthesis, Characterization and Structure - Property Relations

DTIC Science & Technology

2006-03-31

crystals by the flux method and modified Bridgman technique, the growth results were hardly reproducible, and the quality of the crystals was still a serious... growth . 2.2.1.2.2) Solution Bridgman Growth A modified Bridgman method using excess of PbO as solvent was developed for the growth of PZNT91/9 crystals ...of growth , the grown crystal can be rotated via the A120 3 rod which was driven by a motor at a speed of 0 to 30 rmp. Figure 15(b) gives the

Revealing the preferred interlayer orientations and stackings of two-dimensional bilayer gallium selenide crystals.

PubMed

Li, Xufan; Basile, Leonardo; Yoon, Mina; Ma, Cheng; Puretzky, Alexander A; Lee, Jaekwang; Idrobo, Juan C; Chi, Miaofang; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

2015-02-23

Characterizing and controlling the interlayer orientations and stacking orders of two-dimensional (2D) bilayer crystals and van der Waals (vdW) heterostructures is crucial to optimize their electrical and optoelectronic properties. The four polymorphs of layered gallium selenide (GaSe) crystals that result from different layer stackings provide an ideal platform to study the stacking configurations in 2D bilayer crystals. Through a controllable vapor-phase deposition method, bilayer GaSe crystals were selectively grown and their two preferred 0° or 60° interlayer rotations were investigated. The commensurate stacking configurations (AA' and AB stacking) in as-grown bilayer GaSe crystals are clearly observed at the atomic scale, and the Ga-terminated edge structure was identified using scanning transmission electron microscopy. Theoretical analysis reveals that the energies of the interlayer coupling are responsible for the preferred orientations among the bilayer GaSe crystals. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Morphological, spectroscopic and thermal studies of samarium chloride coordinated single crystal grown by slow evaporation method

NASA Astrophysics Data System (ADS)

Slathia, Goldy; Raina, Bindu; Gupta, Rashmi; Bamzai, K. K.

2018-05-01

The synthesis of samarium chloride coordinated single crystal was carried out at room temperature by slow evaporation method. The crystal possesses a well defined hexagonal morphology with six symmetrically equivalent growth sectors separated by growth boundaries. The theoretical morphology has been established by structural approach using Bravaise-Friedele-Donnaye-Harker (BFDH) law. Fourier transform infra red spectroscopy was carried in order to study the geometry and structure of the crystal. The detailed thermogravimetric analysis elucidates the thermal stability of the complex.

Effect of temperature gradient on the optical quality of mercurous chloride crystals

NASA Technical Reports Server (NTRS)

Singh, N. B.; Davies, D. K.; Gottlieb, M.; Henningsen, T.; Mazelsky, R.

1989-01-01

Single crystals of mercurous chloride were grown at temperature gradients of 8, 11 and 17 K/cm by the physical vapor transport method. The optical quality of these crystals was evaluated by measuring bulk scattering and inhomogeneity of refractive index by birefringence interferometry. It was observed that a high temperature gradient at the solid-vapor interface induced thermal stresses and crystals showed higher scattering and irregular fringes.

Magnetic and magnetostrictive behavior of Dy 3+ doped CoFe 2O 4 single crystals grown by flux method

NASA Astrophysics Data System (ADS)

Kambale, Rahul C.; Song, K. M.; Won, C. J.; Lee, K. D.; Hur, N.

2012-02-01

We studied the effect of Dy 3+ content on the magnetic properties of cobalt ferrite single crystal. The single crystals of CoFe 1.9Dy 0.1O 4 were grown by the flux method using Na 2B 4O 7.10 H 2O (Borax) as a solvent (flux). The black and shiny single crystals were obtained as a product. The X-ray diffraction analysis at room temperature confirmed the spinel cubic structure with lattice constant a=8.42 Å of the single crystals. The compositional analysis endorses the presence of constituents Co, Fe and Dy elements after sintering at 1300 °C within the final structure. The magnetic hysteresis measurements at various temperatures viz. 10 K, 100 K, 200 K and 300 K reveal the soft ferrimagnetic nature of the single crystal than that of for pure CoFe 2O 4. The observed saturation magnetization ( Ms) and coercivity ( Hc) are found to be lower than that of pure CoFe 2O 4 single crystal. The magnetostriction ( λ) measurement was carried out along the [001] direction. The magnetic measurements lead to conclude that the present single crystals can be used for magneto-optic recording media.

A comparison of point defects in Cd1-xZnxTe1-ySey crystals grown by Bridgman and traveling heater methods

NASA Astrophysics Data System (ADS)

Gul, R.; Roy, U. N.; Camarda, G. S.; Hossain, A.; Yang, G.; Vanier, P.; Lordi, V.; Varley, J.; James, R. B.

2017-03-01

In this paper, the properties of point defects in Cd1-xZnxTe1-ySey (CZTS) radiation detectors are characterized using deep-level transient spectroscopy and compared between materials grown using two different methods, the Bridgman method and the traveling heater method. The nature of the traps was analyzed in terms of their capture cross-sections and trap concentrations, as well as their effects on the measured charge-carrier trapping and de-trapping times, and then compared for the two growth techniques. The results revealed that Se addition to CdZnTe can reduce the VCd- concentration. In Travelling Heater Method (THM) and Bridgman Method (BM) grown CZTS detectors, besides a few similarities in the shallow and medium energy traps, there were major differences in the deep traps. It was observed that the excess-Te and lower growth-temperature conditions in THM-grown CZTS led to a complete compensation of VCd- and two additional traps (attributed to Tei- and TeCd++ appearing at around Ev + 0.26 eV and Ec - 0.78 eV, respectively). The 1.1-eV deep trap related to large Te secondary phases was a dominant trap in the BM-grown CZTS crystals. In addition to i-DLTS data, the effects of point defects induced due to different processing techniques on the detector's resistivity, spectral response to gammas, and μτ product were determined.

Structure and magnetic properties of flux grown single crystals of Co3-xFexSn2S2 shandites

NASA Astrophysics Data System (ADS)

Kassem, Mohamed A.; Tabata, Yoshikazu; Waki, Takeshi; Nakamura, Hiroyuki

2016-01-01

We report a successful single crystal growth of the shandite-type half-metallic ferromagnet Co3Sn2S2, and its Fe-substituted compounds, Co3-xFexSn2S2, by employing the flux method. Although Fe3Sn2S2 is unstable phase, we found that using the self Sn flux enables us to obtain single phase crystals up to x=0.53. The chemical composition of the grown plate-shaped single crystals was examined using wavelength-dispersive X-ray spectroscopy. The shandite structure with R 3 ̅m symmetry was confirmed by powder X-ray diffraction and the crystal structure parameters were refined using the Rietveld method. Magnetization measurements show suppression of the ferromagnetic order upon Fe-substitution , as well as in other substituted systems such as In- and Ni-substituted Co3Sn2S2. The almost identical magnetic phase diagrams of the Fe- and In-substituted compounds indicate that the electron number is dominantly significant to the magnetism in the Co-based shandite.

Bridgman Growth of Germanium Crystals in a Rotating Magnetic Field

NASA Technical Reports Server (NTRS)

Volz, M. P.; Szofran, F. R.; Cobb, S. D.; Schweizer, M.; Walker, J. S.

2005-01-01

A series of (100)-oriented gallium-doped germanium crystals has been grown by the vertical Bridgman method and under the influence of a rotating magnetic field (RMF). Time-dependent flow instabilities occur when the critical magnetic Taylor number (Tm(sup c)) is exceeded, and this can be observed by noting the appearance of striations in the grown crystals. Tm(sup c) decreases as the aspect ratio of the melt increases, and approaches the theoretical limit expected for an infinite cylinder. Intentional interface demarcations are introduced by pulsing the RMF on and off The RMF has a marked affect on the interface shape, changing it from concave to nearly flat as the RMF strength is increased.

Nonlinear optical properties of flux growth KTiOPO4

NASA Astrophysics Data System (ADS)

Stolzenberger, Richard A.

1988-09-01

The properties of large flux grown KTiOPO4 second harmonic generators were measured. A technique which provides a sensitive assessment of crystal uniformity is described. Optically perfect second harmonic generation crystals of up to 1 cu cm were found to have nonlinear optical properties comparable with those grown by other methods. A Q-switched Nd:YAG laser was used to determine temperature acceptance width-length product (20 C cm), angular acceptance width-length product (13 mrad cm), and doubling efficiency (50 percent). Spectral bandwidth (4.5 A cm) and wavefront distortion (1/4 wave at 633 nm) were also measured. The dependence of these properties on crystal homogeneity is demonstrated.

Crystal growth of Bi{sub 2}Te{sub 3} and noble cleaved (0001) surface properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.ru; Functional Electronics Laboratory, Tomsk State University, Tomsk 634050; Golyashov, V.A.

2016-04-15

A high quality Bi{sub 2}Te{sub 3} crystal has been grown by Bridgman method with the use of rotating heat field. The phase purity and bulk structural quality of the crystal have been verified by XRD analysis and rocking curve observation. The atomically smooth Bi{sub 2}Te{sub 3}(0001) surface with an excellent crystallographic quality is formed by cleavage in the air. The chemical and microstructural properties of the surface have been evaluated with RHEED, AFM, STM, SE and XPS. The Bi{sub 2}Te{sub 3}(0001) cleaved surface is formed by atomically smooth terraces with the height of the elemental step of ~1.04±0.1 nm, asmore » estimated by AFM. There is no surface oxidation process detected over a month keeping in the air at normal conditions, as shown by comparative core level photoelectron spectroscopy. - Graphical abstract: A high quality Bi{sub 2}Te{sub 3} crystal has been grown by Bridgman method with the use of rotating heat field and the Bi{sub 2}Te{sub 3}(0001) cleaved surface has been evaluated with RHEED, AFM, STM, SE and XPS. - Highlights: • High-quality Bi{sub 2}Te{sub 3} crystal of 10 mm in diameter and 50 mm long have been grown. • The high-purity cleaved Bi{sub 2}Te{sub 3}(0001) surface has been evaluated by RHEED, AFM, STM and XPS methods. • The Bi{sub 2}Te{sub 3} surface covered by atomically smooth (0001) terraces is chemically stable for a long time.« less

Hierarchical microstructures in CZT

NASA Astrophysics Data System (ADS)

Sundaram, S. K.; Henager, C. H.; Edwards, D. J.; Schemer-Kohrn, A. L.; Bliss, M.; Riley, B. R.; Toloczko, M. B.; Lynn, K. G.

2011-10-01

Advanced characterization tools, such as electron backscatter diffraction and transmitted IR microscopy, are being applied to study critical microstructural features and orientation relations in as-grown CZT crystals to aid in understanding the relation between structure and properties in radiation detectors. Even carefully prepared single crystals of CZT contain regions of slight misorientation, Te-particles, and dislocation networks that must be understood for more accurate models of detector response. This paper describes initial research at PNNL into the hierarchy of microstructures observed in CZT grown via the vertical gradient freeze or vertical Bridgman method at PNNL and WSU.

Single crystal growth of the Er2PdSi3 intermetallic compound

NASA Astrophysics Data System (ADS)

Mazilu, I.; Frontzek, M.; Löser, W.; Behr, G.; Teresiak, A.; Schultz, L.

2005-02-01

Single crystals of the Er2PdSi3 intermetallic compound melting congruently at 1648 ∘C, were grown by a floating zone method with radiation heating. The control of oxygen content was the key factor to avoid oxide precipitates, which can affect effective grain selection in the crystal growth process. Crystals grown at velocities of 5 mm/h with a preferred direction close to (1 0 0) with inclination angles of about 12 ∘ against the rod axis show very distinct facets at the rod surface. The crystals are Pd-depleted and Si-rich with respect to the nominal Er2PdSi3 stoichiometry, but exhibit inferior element segregation. Measurements on oriented single crystalline samples revealed antiferromagnetic ordering below 7 K, a magnetic easy axis parallel to the (0 0 1) axis of the AlB2-type hexagonal unit cell, and anisotropic electric properties.

Quantitative control of CaCO3 growth on quartz crystal microbalance sensors as a signal amplification method.

PubMed

Wu, Congcong; Sun, Zhaomei; Liu, Li-Shang

2017-07-10

The surface crystallization of CaCO 3 on gold was monitored by a quartz crystal microbalance (QCM). Quantitative control of the grown crystals was realized by adjusting the ratio of two functional groups, -N(CH 3 ) 3 and -COOH, on SAMs. Crystals with uniform size, morphology and polymorphism were obtained. The amount of crystals formed was found to increase with an increase in the -COOH group. The proposed quantitative control of crystallization can be an effective mass amplification strategy for QCM to enhance its assay sensitivity.

Growth, structural, thermal, linear and nonlinear optical and laser damage threshold studies of picolinium tartrate monohydrate single crystals.

PubMed

Peramaiyan, G; Pandi, P; Sornamurthy, B M; Bhagavannarayana, G; Mohan Kumar, R

2012-09-01

Picolinium tartrate monohydrate (PTM), a novel organic nonlinear optical material was synthesized and bulk crystals were grown from aqueous solution by slow cooling technique. The cell parameters of the grown crystal were found by single and powder X-ray diffraction analyses. The crystalline perfection of the grown crystals has been analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. The presence of functional groups in the grown crystal was identified by FTIR and FT-Raman spectral analyses. UV-Vis spectral studies reveal PTM crystals are transparent in the wavelength region of 295-1100 nm. The thermal characteristics of PTM were analyzed by TGA/DTA studies. The dielectric and mechanical behaviours of PTM crystals were investigated. Dislocation density was estimated to be 2.89 × 10(3) cm(-2) on the flat-surface of PTM crystals from the etching studies. The laser induced surface damage threshold for the grown crystal was measured using Nd:YAG laser. Its second harmonic generation relative efficiency was measured by Kurtz and Perry powder technique and was observed to be comparable with KDP crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

Vapor Growth and Characterization of Cr-Doped ZnSe Crystals

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Feth, Shari; Volz, M. P.; Matyi, R.; George, M. A.; Chattopadhyay, K.; Burger, A.; Lehoczky, S. L.

1999-01-01

Cr-doped ZnSe single crystals were grown by a self-seeded physical vapor transport technique in both vertical (stabilized) and horizontal configurations. The source materials were mixtures of ZnSe and CrSe. Growth temperatures were in the range of 1140-1150 C and the furnace translation rates were 1.9-2.2 mm/day. The surface morphology of the as-grown crystals was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Different features of the as-grown surface of the vertically and horizontally grown crystals suggest that different growth mechanisms were involved in the two growth configurations. The [Cr] doping levels were determined to be in the range of 1.8-8.3 x 10 (exp 19) cm (exp -3) from optical absorption measurements. The crystalline quality of the grown crystals were examined by high-resolution triple-crystal X-ray diffraction (HRTXD) analysis.

Yb3+-doped cadmium molybdato-tungstate single crystal - Its structural, optical, magnetic and transport properties

NASA Astrophysics Data System (ADS)

Groń, T.; Tomaszewicz, E.; Berkowski, M.; Głowacki, M.; Oboz, M.; Kusz, J.; Sawicki, B.; Kukuła, Z.; Duda, H.

2018-06-01

Single crystal of new cadmium and ytterbium molybdato-tungstate (Cd0.9706⎕0.0098Yb0.0196(MoO4)0.9706(WO4)0.0294, where ⎕ denotes cationic vacancies) has been successfully grown by the Czochralski method in air and under 1 MPa. X-ray crystallographic analysis reveals that the as-grown single crystal belongs to a scheelite-type structure (a = b = 5.15539(12) and c = 11.1919(3) Å, space group I41/a), in which Yb3+ ions do not show long-range order and are randomly distributed in the unit cell, substituting the Cd2+ ones. The as-grown single crystal does not show anisotropy of optical properties, i.e. its direct band gap reaches Eg = 1.76 or 1.75 eV along (100) and (001) crystallographic directions, respectively. The single crystal exhibits paramagnetic state with short-range antiferromagnetic and long-range ferrimagnetic interactions, a magnetization with zero coercivity and, a remanence that is almost a universal function of H/T, characterizing superparamagnetic-like behaviour. Electrical studies of the new ytterbium-doped cadmium molybdato-tungstate single crystal show a relatively small dielectric constant (εr<12), large lossiness of Joule-Lenz type observed at low frequencies as well as nonlinear I-V characteristics of Schottky or Maxwell-Wagner type.

Thermal, spectroscopic and laser properties of Nd3+ in gadolinium scandium gallium garnet crystal produced by optical floating zone method

NASA Astrophysics Data System (ADS)

Tian, Li; Wang, Shuxian; Wu, Kui; Wang, Baolin; Yu, Haohai; Zhang, Huaijin; Cai, Huaqiang; Huang, Hui

2013-12-01

A neodymium-doped gadolinium scandium gallium garnet (Nd:GSGG) single crystal with dimensions of Φ 5 × 20 mm2 has been grown by means of optical floating zone (OFZ). X-ray powder diffraction (XRPD) result shows that the as-grown Nd:GSGG crystal possesses a cubic structure with space group Ia3d and a cell parameter of a = 1.2561 nm. Effective elemental segregation coefficients of the Nd:GSGG as-grown crystal were calculated by using X-ray fluorescence (XRF). The thermal properties of the Nd:GSGG crystal were systematically studied by measuring the specific heat, thermal expansion and thermal diffusion coefficient, and the thermal conductivity of this crystal was calculated. The absorption and luminescence spectra of Nd:GSGG were measured at room temperature (RT). By using the Judd-Ofelt (J-O) theory, the theoretical radiative lifetime was calculated and compared with the experimental result. Continuous wave (CW) laser performance was achieved with the Nd:GSGG at the wavelength of 1062 nm when it was pumped by a laser diode (LD). A maximum output power of 0.792 W at 1062 nm was obtained with a slope efficiency of 11.89% under a pump power of 7.36 W, and an optical-optical conversion efficiency of 11.72%.

Crystal Growth of ZnSe and Related Ternary Compound Semiconductors by Vapor Transport

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Brebrick, R. F.; Burger, A.; Dudley, M.; Matyi, R.; Ramachandran, N.; Sha, Yi-Gao; Volz, M.; Shih, Hung-Dah

1999-01-01

Complete and systematic ground-based experimental and theoretical analyses on the Physical Vapor Transport (PVT) of ZnSe and related ternary compound semiconductors have been performed. The analyses included thermodynamics, mass flux, heat treatment of starting material, crystal growth, partial pressure measurements, optical interferometry, chemical analyses, photoluminescence, microscopy, x-ray diffraction and topography as well as theoretical, analytical and numerical analyses. The experimental results showed the influence of gravity orientation on the characteristics of: (1) the morphology of the as-grown crystals as well as the as-grown surface morphology of ZnSe and Cr doped ZnSe crystals; (2) the distribution of impurities and defects in ZnSe grown crystals; and (3) the axial segregation in ZnSeTe grown crystals.

Protein Crystal Recombinant Human Insulin

NASA Technical Reports Server (NTRS)

1994-01-01

The comparison of protein crystal, Recombiant Human Insulin; space-grown (left) and earth-grown (right). On STS-60, Spacehab II indicated that space-grown crystals are larger and of greater optical clarity than their earth-grown counterparts. Recombiant Human Insulin facilitates the incorporation of glucose into cells. In diabetics, there is either a decrease in or complete lack of insulin, thereby leading to several harmful complications. Principal Investigator is Larry DeLucas.

Synthesis, growth, structural, optical and thermal properties of an organic single crystal: 4-nitroaniline 4-aminobenzoic acid.

PubMed

Silambarasan, A; Rajesh, P; Ramasamy, P

2014-01-24

The organic single crystals of 4-nitroaniline 4-aminobenzoic acid (4NAABA) were grown from ethanol solvent. The lattice parameters of the grown crystal have been confirmed from single crystal XRD analysis. The powder XRD pattern shows the various planes of grown crystal. The FTIR and (1)H NMR spectral analysis confirm the presence of various functional groups and the placement of proton in 4NAABA compound respectively. The UV absorption was carried out which shows the cutoff wavelength around 459 nm. The optical band gap of the crystal has been evaluated from the transmission spectra and absorption coefficient by extrapolation technique. In addition, a fluorescence spectral analysis is carried out for 4NAABA crystals. The thermal properties of crystals were evaluated from thermogravimetrical analysis. It shows that the grown crystal is stable up to 160°C and the crystal has sharp melting point at 151°C. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis, growth, structural, spectroscopic and optical studies of a semiorganic NLO crystal: zinc guanidinium phosphate.

PubMed

Suvitha, A; Murugakoothan, P

2012-02-01

The semi-organic nonlinear optical (NLO) crystal, zinc guanidinium phosphate (ZGuP) has been grown through synthesis between zinc sulphate, guanidine carbonate and orthophosphoric acid from its aqueous solution by slow solvent evaporation technique. Solubility of the synthesized material has been determined for various temperatures using water as solvent. The grown crystal has been characterized by powder X-ray diffraction to confirm the crystal structure. Investigation has been carried out to assign the vibrational frequencies of the grown crystals by Fourier transform infrared spectroscopy technique. (1)H and (13)C FT-NMR have been recorded to elucidate the molecular structure. The optical absorption study confirms the suitability of the crystal for device applications. The second harmonic generation (SHG) efficiency of ZGuP is found to be 1.825 times that of potassium dihydrogen phosphate (KDP). Thermal behavior of the grown crystals has been studied by thermogravimetric and differential thermal analysis. The mechanical properties of the grown crystals have been studied using Vickers microhardness tester. Copyright © 2011 Elsevier B.V. All rights reserved.

Crystallographic analysis of ground and space thermostable T1 lipase crystal obtained via counter diffusion method approach.

PubMed

Mohamad Aris, Sayangku Nor Ariati; Thean Chor, Adam Leow; Mohamad Ali, Mohd Shukuri; Basri, Mahiran; Salleh, Abu Bakar; Raja Abd Rahman, Raja Noor Zaliha

2014-01-01

Three-dimensional structure of thermostable lipase is much sought after nowadays as it is important for industrial application mainly found in the food, detergent, and pharmaceutical sectors. Crystallization utilizing the counter diffusion method in space was performed with the aim to obtain high resolution diffracting crystals with better internal order to improve the accuracy of the structure. Thermostable T1 lipase enzyme has been crystallized in laboratory on earth and also under microgravity condition aboard Progress spacecraft to the ISS in collaboration with JAXA (Japanese Aerospace Exploration Agency). This study is conducted with the aims of improving crystal packing and structure resolution. The diffraction data set for ground grown crystal was collected to 1.3 Å resolution and belonged to monoclinic C2 space group with unit cell parameters a = 117.40 Å, b = 80.95 Å, and c = 99.81 Å, whereas the diffraction data set for space grown crystal was collected to 1.1 Å resolution and belonged to monoclinic C2 space group with unit cell parameters a = 117.31 Å, b = 80.85 Å, and c = 99.81 Å. The major difference between the two crystal growth systems is the lack of convection and sedimentation in microgravity environment resulted in the growth of much higher quality crystals of T1 lipase.

Growth Temperature Dependence of Morphology of GaN Single Crystals in the Na-Li-Ca Flux Method

NASA Astrophysics Data System (ADS)

Wu, Xi; Hao, Hangfei; Li, Zhenrong; Fan, Shiji; Xu, Zhuo

2018-02-01

In this paper, the effect of growth temperature on the morphology and transparency of the GaN crystals obtained by the Li-Ca-added Na Flux method was studied. Addition of Li-Ca was attempted to control the growth habit and further improve transparency of GaN crystals. The samples with wurtzite structure of GaN were confirmed by the x-ray powder diffraction analysis. GaN single crystal with maximum size of about 6 mm was grown at 750°C. As the growth temperature was increased from 700°C to 850°C, the morphology of the crystals changed from pyramid to prism, and their surfaces became smooth. It was found that high growth temperature was beneficial to obtain a transparent crystal, but the evaporation of sodium would suppress its further growth. The E 2 (high) mode in the Raman spectra was at 568 cm-1, and the full-width at half-maximum values of this peak for the crystals obtained at 700°C, 750°C, 800°C, and 850°C were 7.5 cm-1, 10.3 cm-1, 4.4 cm-1, and 4.0 cm-1, respectively. It indicates that all the crystals are stress free and the transparent crystal grown at high temperature has high structural quality or low impurity concentrations.

Investigation on synthesis, growth, structure and physical properties of AgGa0.5In0.5S2 single crystals for Mid-IR application

NASA Astrophysics Data System (ADS)

Karunagaran, N.; Ramasamy, P.

2018-02-01

Silver Gallium Indium Sulfide (AgGa0.5In0.5S2) belongs to the family of AIBIIIC2VI ternary compound semiconductors which crystallize in the chalcopyrite structure. Synthesis of the polycrystalline material from the starting elements is achieved using melt temperature oscillation method. The AgGa0.5In0.5S2 single crystals have been grown by the vertical Bridgman technique. The synthesized AgGa0.5In0.5S2 polycrystalline charge was confirmed by powder XRD. The peak positions are in good agreement with the powder diffraction file. Thermal property was analyzed using differential scanning calorimetry (DSC) technique. The melting point of the crystal is 896 °C and freezing point is 862 °C. The unit cell parameters were confirmed by single crystal X-ray. The transmittance of the grown crystal is 55% in the NIR region and 60% in the mid-IR region. The optical band gap was found to be 2.0 eV. The stoichiometric composition of AgGa0.5In0.5S2 was measured using energy dispersive spectrometry (EDS). The photoluminescence behavior of AgGa0.5In0.5S2 has been analyzed. The resistivity of the grown single crystal has been measured.

Ultratough CVD single crystal diamond and three dimensional growth thereof

DOEpatents

Hemley, Russell J [Washington, DC; Mao, Ho-kwang [Washington, DC; Yan, Chih-shiue [Washington, DC

2009-09-29

The invention relates to a single-crystal diamond grown by microwave plasma chemical vapor deposition that has a toughness of at least about 30 MPa m.sup.1/2. The invention also relates to a method of producing a single-crystal diamond with a toughness of at least about 30 MPa m.sup.1/2. The invention further relates to a process for producing a single crystal CVD diamond in three dimensions on a single crystal diamond substrate.

Protein crystal growth in microgravity review of large scale temperature induction method: Bovine insulin, human insulin and human α-interferon

NASA Astrophysics Data System (ADS)

Long, Marianna M.; Bishop, John Bradford; Delucas, Lawrence J.; Nagabhushan, Tattanhalli L.; Reichert, Paul; Smith, G. David

1997-01-01

The Protein Crystal Growth Facility (PCF) is space-flight hardware that accommodates large scale protein crystal growth experiments using temperature change as the inductive step. Recent modifications include specialized instrumentation for monitoring crystal nucleation with laser light scattering. This paper reviews results from its first seven flights on the Space Shuttle, the last with laser light scattering instrumentation in place. The PCF's objective is twofold: (1) the production of high quality protein crystals for x-ray analysis and subsequent structure-based drug design and (2) preparation of a large quantity of relatively contaminant free crystals for use as time-release protein pharmaceuticals. The first three Shuttle flights with bovine insulin constituted the PCF's proof of concept, demonstrating that the space-grown crystals were larger and diffracted to higher resolution than their earth-grown counterparts. The later four PCF missions were used to grow recombinant human insulin crystals for x-ray analysis and continue productions trials aimed at the development of a processing facility for crystalline recombinant a-interferon.

Convection effects in protein crystal growth

NASA Technical Reports Server (NTRS)

Roberts, Glyn O.

1988-01-01

Protein crystals for X-ray diffraction study are usually grown resting on the bottom of a hanging drop of a saturated protein solution, with slow evaporation to the air in a small enclosed cell. The evaporation rate is controlled by hanging the drop above a reservoir of water, with its saturation vapor pressure decreased by a low concentration of a passive solute. The drop has a lower solute concentration, and its volume shrinks by evaporation until the molecular concentrations match. Protein crystals can also be grown from a seed crystal suspended or supported in the interior of a supersaturated solution. The main analysis of this report concerns this case because it is less complicated than hanging-drop growth. Convection effects have been suggested as the reason for the apparent cessation of growth at a certain rather small crystal size. It seeems that as the crystal grows, the number of dislocations increases to a point where further growth is hindered. Growth in the microgravity environment of an orbiting space vehicle has been proposed as a method for obtaining larger crystals. Experimental observations of convection effects during the growth of protein crystals have been reported.

Growth of Nd doped (Lu, Gd)3(Ga, Al)5O12 single crystal by the micro pulling down method and their scintillation properties

NASA Astrophysics Data System (ADS)

Kamada, Kei; Kurosawa, Shunsuke; Yamaji, Akihiro; Shoji, Yasuhiro; Pejchal, Jan; Ohashi, Yuji; Yokota, Yuui; Yoshikawa, Akira

2015-03-01

Nd 1 mol% doped (Lu, Gd)3(Ga, Al)5O12 (LGGAG) single crystals were grown by the micro-pulling down (μ-PD) method. Luminescence and scintillation properties such as absorption, excitation and emission spectra, light yield and decay time were evaluated. Nd1%:Lu3Al5O12 showed the highest light output of around 8200 photons/MeV among the grown crystals. Scintillation decay time of Nd:Y3Al5O12 was 1.32 μs (36%) 2.02 μs (64%). Nd:Lu3Ga3Al2O12 was relatively high dense scintillator of 7.38 g/cm3 with good light yield of 6800 photons/MeV and scintillation decay time of 0.20 μs (5%) 2.60 μs (95%).

Growth and performance research of Tb3Ga5O12 magneto-optical crystal

NASA Astrophysics Data System (ADS)

Jin, Weizhao; Ding, Jingxin; Guo, Li; Gu, Qi; Li, Chun; Su, Liangbi; Wu, Anhua; Zeng, Fanming

2018-02-01

Tb3Ga5O12 (TGG) crystal was grown successfully by the Czochralski method in an iridium crucible with radio frequency (RF)-induced heating under high purity 80%N2 + 20% CO2 atmosphere. None impurity peaks could be found in the XRD patterns compared to standard cards of TGG. Transmittance spectrum was investigated in the visible-near infrared region (VIS-NIR) at room temperature, which indicated the TGG crystal had high transmittance at 500-1100 nm. The Faraday rotations, Verdet constants and magnetic susceptibility of (1 1 1), (1 0 0), (1 1 0) of as-grown crystal have been discussed in detail confirming that Faraday effects of the TGG crystals are anisotropic which is related with magnetic susceptibility, and the Faraday effects of [1 1 1] have been proved to be the best, and the Verdet constants of [1 1 1] was also investigated at different wavelength at room temperature. The thermal conductivity and laser induced damage threshold of the crystal were also analyzed in detailed.

Purification, crystallization and preliminary crystallographic study of an IDS-epimerase from Agrobacterium tumefaciens BY6

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bäuerle, Bettina; Sandalova, Tatyana; Schneider, Gunter

2006-08-01

This is the first report of the crystallization of an IDS-epimerase from A. tumefaciens BY6 and its l-selenomethionine derivative. The initial degradation of all stereoisomers of the complexing agent iminodisuccinate (IDS) is enabled by an epimerase in the bacterial strain Agrobacterium tumefaciens BY6. This protein was produced in Escherichia coli, purified and crystallized by the hanging-drop vapour-diffusion method. Crystals of IDS-epimerase were obtained under several conditions. The best diffracting crystals were grown in 22% PEG 3350, 0.2 M (NH{sub 4}){sub 2}SO{sub 4} and 0.1 M bis-Tris propane pH 7.2 at 293 K. These crystals belong to the monoclinic space groupmore » P2{sub 1}, with unit-cell parameters a = 55.4, b = 104.2, c = 78.6 Å, β = 103.3°, and diffracted to 1.7 Å resolution. They contain two protein molecules per asymmetric unit. In order to solve the structure using the MAD phasing method, crystals of the l-selenomethionine-substituted epimerase were grown in the presence of 20% PEG 3350, 0.2 M Na{sub 2}SO{sub 4} and 0.1 M bis-Tris propane pH 8.5.« less

Process development and characterization of centrosymmetric semiorganic nonlinear optical crystal: 4-dimethylaminopyridine potassium chloride

NASA Astrophysics Data System (ADS)

Johnson, J.; Srineevasan, R.; Sivavishnu, D.

2018-06-01

Centrosymmetric semiorganic crystal 4-dimethylaminopyridine potassium chloride (4-DMAPKC) has been grown successfully by using slow evaporation solution growth technique. Powder x-ray diffraction shows the 4-DMAPKC crystal has good crystalline nature. Single crystal XRD shows that the grown 4-DMAPKC is cubic crystal system with cell parameters a = 3.09 Å, b = 3.09 Å, c = 3.09 Å. Investigation has been carried out to assign the Vibrational frequencies of the grown crystal by FTIR spectral studies. UVsbnd Visible NIR optical absorption spectral studies in the range of 200-1100 nm shows low absorption in UVsbnd Visible region with lower cutoff wave length at 261 nm and optical band gap energy was found as Eg = 5.52 eV. Optically transmittance spectral shows 4-DMAPKC crystal is very good transparency in UV-Visible NIR region. Thermogravimetry and differential thermal (TG-DTA) analysis were carried out. Dielectric studies of as grown crystal sample exhibit low dielectric constant and loss at higher frequencies and attests the nonlinear optical activity. Micro hardness studies of as grown crystal were discussed. Second harmonic generation (SHG) efficiency of the 4-DMAPKC is 0.69 times as that of KDP.

Bridgman Growth of Germanium Crystals in a Rotating Magnetic Field

NASA Technical Reports Server (NTRS)

Volz, M. P.; Schweizer, M.; Cobb, S. D.; Walker, J. S.; Szofran, F. R.; Curreri, Peter A. (Technical Monitor)

2002-01-01

A series of (100)-oriented gallium-doped germanium crystals have been grown by the Bridgman method and under the influence of a rotating magnetic field (RMF). The RMF has a marked affect on the interface shape, changing it from concave to nearly flat. The onset of time-dependent flow instabilities occurs when the critical magnetic Taylor number is exceeded, and this can be observed by noting the appearance of striations in the grown crystals. The critical magnetic Taylor number is a sensitive function of the aspect ratio and, as the crystal grows under a constant applied magnetic field, the induced striations change from nonperiodic to periodic, undergo a period-doubling transition, and then cease to exist. Also, by pulsing the RMF on and off, it is shown that intentional interface demarcations can be introduced.

Growth and characterization of metal doped and quasi mixed crystals based on ZnCd(SCN)4

NASA Astrophysics Data System (ADS)

Latha, C.; Mahadevan, C. K.; Guo, Li; Liu, Jinghe

2018-03-01

In order to understand the effect of forming hybrid crystals by doping with metallic impurities or by quasi mixing on the physicochemical properties of the basic material crystal, we have grown by the free evaporation method at room temperature and characterized (chemically, structurally, optically and electrically) un-doped and K+/Ca2+/Mn2+/Mg2+/Cu2+ doped (with 1 mol% concentration) ZnCd(SCN)4 and ZnxCd(2-x)(SCN)4 (with x = 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0) single crystals. Single crystals could be grown with x = 0.0 (leading to Cd(SCN)2) but not when x = 2.0 (leading to Zn(SCN)2). Results obtained in the present study through X-ray diffraction and EDAX spectral measurements indicate the formation of the above hybrid crystals. The optical (UV-Vis-NIR spectral and SHG efficiency) measurements indicate significant changes in optical transmittance and SHG efficiency due to doping as well as quasi mixing. Dielectric measurements made in the temperature range 40-150 °C with a fixed frequency of 1 kHz indicate a normal dielectric behavior for all the eleven crystals grown. Moreover, the present study indicates an increase of dielectric constant and SHG efficiency when ZnCd(SCN)4 crystal is doped with a metallic impurity whereas a decrease of dielectric constant and SHG efficiency when quasi mixing is done.

Crystal growth of artificial snow

NASA Technical Reports Server (NTRS)

Kimura, S.; Oka, A.; Taki, M.; Kuwano, R.; Ono, H.; Nagura, R.; Narimatsu, Y.; Tanii, J.; Kamimiytat, Y.

1984-01-01

Snow crystals were grown onboard the space shuttle during STS-7 and STS-8 to facilitate the investigation of crystal growth under conditions of weightlessness. The experimental design and hardware are described. Space-grown snow crystals were polyhedrons looking like spheres, which were unlike snow crystals produced in experiments on Earth.

Preliminary observations of the effect of solutal convection on crystal morphology

NASA Technical Reports Server (NTRS)

Broom, M. Beth H.; Witherow, William K.; Snyder, Robert S.; Carter, Daniel C.

1988-01-01

Studies to examine the effect of solutal convection on crystal morphology using sucrose as a model system were initiated. Aspect ratios, defined as the width of the 100-plane-oriented face over the width of the 001-plane-oriented face, were determined for oriented crystals which were grown with either the 001-oriented or the 100-oriented face perpendicular to the convective flow. The dependence of the crystal morphology on orientation is much greater for crystals grown with one face occluded than for crystals grown suspended in solution. Many factors appear to interact in a complex fashion to influence crystal morphology.

Electrochemical deposition of silver crystals aboard Skylab 4

NASA Technical Reports Server (NTRS)

Grodzka, P. G.; Facemire, B. R.; Johnston, M. H.; Gates, D. W.

1976-01-01

Silver crystals were grown aboard Skylab 4 by an electro-chemical reaction and subsequently returned to earth for comparison with crystals grown at 1- and 5-g. Both the Skylab and earth-grown crystals show a variety of structures. Certain tendencies in structure dependency on gravity level, however, can be discerned. In addition, downward growing dendrite streamers; upward growing chunky crystal streamers; growth along an air/liquid interface; and ribbon, film, and fiber crystal habits were observed in experiments conducted on the ground with solutions of varying concentrations. It was also observed that the crystal structures of space and ground electro-deposited silver crystals were very similar to the structures of germanium selenide and germanium telluride crystals grown in space and on the ground by a vapor transport technique. Consideration of the data leads to the conclusions that: (1) the rate of electrochemical displacement of silver ions from a 5 percent aqueous solution by copper is predominantly diffussion controlled in space and kinetically controlled in 1- and higher-g because of augmentation of mass transport by convection; (2) downward and upward crystal streamers are the result of gravity-driven convection, the flow patterns of which can be delineated. Lateral growths along an air/liquid interface are the result of surface-tension-driven convection, the pattern of which also can be delineated; (3) electrolysis in space or low-g environments can produce either dendritic crystals with more perfect microcrystalline structures or massive, single crystals with fewer defects than those grown on ground or at higher g-levels. Ribbons or films of space-grown silicon crystals would find a ready market for electronic substrate and photocell applications. Space-grown dendritic, metal crystals present the possibility of unique catalysts. Large perfect crystals of various materials are desired for a number of electronic and optical applications; and (4) vapor transport growth of germanium selenide and germanium telluride is affected by convection mechanisms similar to the mechanisms hypothesized for the electrochemical deposition of silver crystals. Evidence and considerations leading to the preceding summaries and conclusions are presented. The implications of the findings and conclusions for technological applications are discussed, and recommendations for further experiments are presented.

Studies on synthesis, growth, structural, thermal, linear and nonlinear optical properties of organic picolinium maleate single crystals.

PubMed

Pandi, P; Peramaiyan, G; Sudhahar, S; Chakkaravarthi, G; Mohan Kumar, R; Bhagavannarayana, G; Jayavel, R

2012-12-01

Picolinium maleate (PM), an organic material has been synthesised and single crystals were grown by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal X-ray diffraction analysis. PM crystal belongs to the monoclinic crystallographic system with space group P2(1)/c. The crystalline perfection of the grown crystals was analyzed by high-resolution X-ray diffraction rocking curve measurements. The presence of functional groups in PM was identified by FTIR and FT-NMR spectral analyses. Thermal behaviour and stability of picolinium maleate were studied by TGA/DTA analyses. UV-Vis spectral studies reveal that PM crystals are transparent in the wavelength region 327-1100 nm. The laser damage threshold value of PM crystal was found to be 4.3 GW/cm(2) using Nd:YAG laser. The Kurtz and Perry powder second harmonic generation technique confirms the nonlinear optical property of the grown crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

Growth and dielectric, mechanical, thermal and etching studies of an organic nonlinear optical L-arginine trifluoroacetate (LATF) single crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arjunan, S.; Department of Physics, Presidency College, Chennai 600005; Mohan Kumar, R.

2008-08-04

L-arginine trifluoroacetate, an organic nonlinear optical material, has been synthesized from aqueous solution. Bulk single crystal of dimension 57 mm x 5 mm x 3 mm has been grown by temperature lowering technique. Powder X-ray diffraction studies confirmed the monoclinic structure of the grown L-arginine trifluoroacetate crystal. Linear optical property of the grown crystal has been studied by UV-vis spectrum. Dielectric response of the L-arginine trifluoroacetate crystal was analysed for different frequencies and temperatures in detail. Microhardness study on the sample reveals that the crystal possesses relatively higher hardness compared to many organic crystals. Thermal analyses confirmed that the L-argininemore » trifluoroacetate material is thermally stable upto 212 deg. C. The etching studies have been performed to assess the perfection of the L-arginine trifluoroacetate crystal. Kurtz powder second harmonic generation test confirms the nonlinear optical properties of the as-grown L-arginine trifluoroacetate crystal.« less

Crystal Growth of ZnSe and Related Ternary Compound Semiconductors by Vapor Transport

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Brebrick, R. F.; Burger, A.; Dudley, M.; Ramachandran, N.

2003-01-01

The objective of the project is to determine the relative contributions of gravity-driven fluid flows to the compositional distribution, incorporation of impurities and defects, and deviation from stoichiometry observed in the crystals grown by vapor transport as results of buoyance-driven convection and growth interface fluctuations caused by irregular fluid-flows. ZnSe and related ternary compounds, such as ZnSeS and ZnSeTe, were grown by vapor transport technique with real time in-situ non-invasive monitoring techniques. The grown crystals were characterized extensively to correlate the grown crystal properties with the growth conditions.

Method for the growth of large low-defect single crystals

NASA Technical Reports Server (NTRS)

Powell, J. Anthony (Inventor); Neudeck, Philip G. (Inventor); Trunek, Andrew J. (Inventor); Spry, David J. (Inventor)

2008-01-01

A method and the benefits resulting from the product thereof are disclosed for the growth of large, low-defect single-crystals of tetrahedrally-bonded crystal materials. The process utilizes a uniquely designed crystal shape whereby the direction of rapid growth is parallel to a preferred crystal direction. By establishing several regions of growth, a large single crystal that is largely defect-free can be grown at high growth rates. This process is particularly suitable for producing products for wide-bandgap semiconductors, such as SiC, GaN, AlN, and diamond. Large low-defect single crystals of these semiconductors enable greatly enhanced performance and reliability for applications involving high power, high voltage, and/or high temperature operating conditions.

Growth, optical, luminescence, thermal and mechanical behavior of an organic single crystal: 3-Acetyl-2-methyl-4-phenylquinolin-1-ium chloride.

PubMed

Nirosha, M; Kalainathan, S; Sarveswari, S; Vijayakumar, V

2014-04-05

A single crystal of 3-acetyl-2-methyl-4-phenylquinolin-1-ium chloride has grown by slow evaporation solution growth technique using ethanol as solvent. The structural, thermal, optical and mechanical property has studied for the grown crystal. Single crystal XRD revealed that the crystal belongs to monoclinic system with space group P21/c. The presences of Functional groups in the crystallized material have confirmed using the FTIR vibrational spectrum. The optical absorbance spectrum recorded from 190 to 1100nm shows the cut-off wavelength occurs at 371nm. The material shows its transparency in the entire region of the visible spectrum. The photoluminescence spectrum shows the ultraviolet and blue emission in the crystal. Thermogravimetric and differential thermal analysis reveal the thermal stability of the grown crystal. Etching study shows the grown mechanism and surface features of the crystal. Vickers microhardness studies have carried out on the (01-1) plane to understand the mechanical properties of the grown crystal. The hardness of the title compound increases on increasing the load. The Meyer's index number (n), and the stiffness constants for different loads has calculated and reported. Copyright © 2013 Elsevier B.V. All rights reserved.

Enhanced ferroelectric properties and thermal stability of nonstoichiometric 0.92(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3 single crystals

NASA Astrophysics Data System (ADS)

Zhang, Haiwu; Chen, Chao; Zhao, Xiangyong; Deng, Hao; Li, Long; Lin, Di; Li, Xiaobing; Ren, Bo; Luo, Haosu; Yan, Jun

2013-11-01

Bi deficient, Mn doped 0.92(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3 single crystals were grown by carefully controlled top-seeded solution growth method. Local structures were investigated by transmission electron microscopy. The site occupation and valence state of manganese were characterized by electron paramagnetic resonance spectrum. The leakage current density in the as-grown single crystals is effectively depressed. The introduced defect complexes suppress the temperature induced phase transformation, increasing the depolarization temperature (165 °C) and thermal stability of ferroelectric properties.

Growth, and magnetic study of Sm0.4Er0.6FeO3 single crystal grown by optical floating zone technique

NASA Astrophysics Data System (ADS)

Wu, Anhua; Zhao, Xiangyang; Man, Peiwen; Su, Liangbi; Kalashnikova, A. M.; Pisarev, R. V.

2018-03-01

Sm0.4Er0.6FeO3 single crystals were successfully grown by optical floating zone method; high quality samples with various orientations were manufactured. Based on these samples, Magnetic property of Sm0.4Er0.6FeO3 single crystals were investigated systemically by means of the temperature dependence of magnetization. It indicated that compositional variations not only alter the spin reorientation temperature, but also the compensation temperature of the orthoferrites. Unlike single rare earth orthoferrites, the reversal transition temperature point of Sm0.4Er0.6FeO3 increases as magnetic field increases, which is positive for designing novel spin switching or magnetic sensor device.

Applications of thermal-gradients method for the optimization of α-amylase crystallization conditions based on dynamic and static light scattering data

NASA Astrophysics Data System (ADS)

Delboni, L. F.; Iulek, J.; Burger, R.; da Silva, A. C. R.; Moreno, A.

2002-02-01

The expression, purification, crystallization, and characterization by X-ray diffraction of α-amylase are described here. Dynamic and static light scattering methods with a temperature controller was used to optimize the crystallization conditions of α-amylase from Bacillus stearothermophilus an important enzyme in many fields of industrial activity. After applying thermal gradients for growing crystals, X-ray cryo-crystallographic methods were employed for the data collection. Crystals grown by these thermal-gradients diffracted up to a maximum resolution of 3.8 Å, which allowed the determination of the unit cell constants as follows: a=61.7 Å, b=86.7 Å, c=92.2 Å and space group C222 (or C222 1).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sathyalakshmi, R.; Bhagavannarayana, G.; Ramasamy, P.

L-(+)-Glutamic acid hydro bromide, an isomorphic salt of L-glutamic acid hydrochloride, was synthesized and the synthesis was confirmed using Fourier transform infrared analysis. Solubility of the material in water was determined. L-Glutamic acid hydro bromide crystals were grown by low temperature solution growth using the solvent evaporation technique. Single crystal X-ray diffraction studies were carried out and the cell parameters, atomic co-ordinates, bond lengths and bond angles were reported. High-resolution X-ray diffraction studies were carried out and good crystallinity for the grown crystal was observed from the diffraction curve. The grown crystals were subjected to dielectric studies. Ultraviolet-visible-near infrared spectralmore » analysis shows good optical transmission in the visible and infrared region of the grown crystals. The second harmonic generation efficiency of L-glutamic acid hydro bromide crystal was determined using the Kurtz powder test and it was found that it had efficiency comparable with that of the potassium di-hydrogen phosphate crystal.« less

Anisotropy of electrical resistivity in PVT grown WSe2-x crystals

NASA Astrophysics Data System (ADS)

Solanki, G. K.; Patel, Y. A.; Agarwal, M. K.

2018-05-01

Single crystals of p-type WSe2 and WSe1.9 were grown by a physical vapour transport technique. The anisotropy in d.c. electrical resistivity was investigated in these grown crystals. The off-stoichiometric WSe1.9 exhibited a higher anisotropy ratio as compared to WSe2 crystals. The electron microscopic examination revealed the presence of a large number of stacking faults in these crystals. The resistivity enhancement along the c-axis and anisotropic effective mass ratio explained on the basis of structural disorder introduced due to off-stoichiometry.

Characterization of TlBrxCl1-x Crystals for Radiation Detectors

NASA Astrophysics Data System (ADS)

Onodera, Toshiyuki; Hitomi, Keitaro; Onodera, Chikara; Shoji, Tadayoshi; Mochizuki, Katsumi

2012-08-01

Thallium bromide chloride TlBrxCl1-x crystals have been evaluated as a material used for fabrication of room temperature radiation detectors. In this study, TlBrxCl1-x crystals with various chlorine (Cl) concentrations were grown by the travelling molten zone method and the detectors were fabricated from the crystals. The optical properties of the crystals were evaluated by measuring the transmittances. The charge transport properties were characterized by the Hecht analysis. The band gap energy of the crystals proportionally increased with Cl concentration. Mobility-lifetime products (μτ) of the crystals decreased with increasing Cl concentration.

Low-Temperature Growth of Two-Dimensional Layered Chalcogenide Crystals on Liquid.

PubMed

Zhou, Yubing; Deng, Bing; Zhou, Yu; Ren, Xibiao; Yin, Jianbo; Jin, Chuanhong; Liu, Zhongfan; Peng, Hailin

2016-03-09

The growth of high-quality two-dimensional (2D) layered chalcogenide crystals is highly important for practical applications in future electronics, optoelectronics, and photonics. Current route for the synthesis of 2D chalcogenide crystals by vapor deposition method mainly involves an energy intensive high-temperature growth process on solid substrates, often suffering from inhomogeneous nucleation density and grain size distribution. Here, we first demonstrate a facile vapor-phase synthesis of large-area high-quality 2D layered chalcogenide crystals on liquid metal surface with relatively low surface energy at a growth temperature as low as ∼100 °C. Uniform and large-domain-sized 2D crystals of GaSe and GaxIn1-xSe were grown on liquid metal surface even supported on a polyimide film. As-grown 2D GaSe crystals have been fabricated to flexible photodetectors, showing high photoresponse and excellent flexibility. Our strategy of energy-sustainable low-temperature growth on liquid metal surface may open a route to the synthesis of high-quality 2D crystals of Ga-, In-, Bi-, Hg-, Pb-, or Sn-based chalcogenides and halides.

Group III-nitride thin films grown using MBE and bismuth

DOEpatents

Kisielowski, Christian K.; Rubin, Michael

2002-01-01

The present invention comprises growing gallium nitride films in the presence of bismuth using MBE at temperatures of about 1000 K or less. The present invention further comprises the gallium nitride films fabricated using the inventive fabrication method. The inventive films may be doped with magnesium or other dopants. The gallium nitride films were grown on sapphire substrates using a hollow anode Constricted Glow Discharge nitrogen plasma source. When bismuth was used as a surfactant, two-dimensional gallium nitride crystal sizes ranging between 10 .mu.m and 20 .mu.m were observed. This is 20 to 40 times larger than crystal sizes observed when GaN films were grown under similar circumstances but without bismuth. It is thought that the observed increase in crystal size is due bismuth inducing an increased surface diffusion coefficient for gallium. The calculated value of 4.7.times.10.sup.-7 cm.sup.2 /sec. reveals a virtual substrate temperature of 1258 K which is 260 degrees higher than the actual one.

Group III-nitride thin films grown using MBE and bismuth

DOEpatents

Kisielowski, Christian K.; Rubin, Michael

2000-01-01

The present invention comprises growing gallium nitride films in the presence of bismuth using MBE at temperatures of about 1000 K or less. The present invention further comprises the gallium nitride films fabricated using the inventive fabrication method. The inventive films may be doped with magnesium or other dopants. The gallium nitride films were grown on sapphire substrates using a hollow anode Constricted Glow Discharge nitrogen plasma source. When bismuth was used as a surfactant, two-dimensional gallium nitride crystal sizes ranging between 10 .mu.m and 20 .mu.m were observed. This is 20 to 40 times larger than crystal sizes observed when GaN films were grown under similar circumstances but without bismuth. It is thought that the observed increase in crystal size is due bismuth inducing an increased surface diffusion coefficient for gallium. The calculated value of 4.7.times.10.sup.-7 cm.sup.2 /sec. reveals a virtual substrate temperature of 1258 K which is 260 degrees higher than the actual one.

Crystal Growth and Characterization of CdTe Grown by Vertical Gradient Freeze

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Lehoczky, S. L.; Raghothamachar, B.; Dudley, M.

2007-01-01

In this study, crystals of CdTe were grown from melts by the unseeded vertical gradient freeze method. The quality of grown crystal were studied by various characterization techniques including Synchrotron White Beam X-ray Topography (SWBXT), chemical analysis by glow discharge mass spectroscopy (GDMS), low temperature photoluminescence (PL), and Hall measurements. The SWBXT images from various angles show nearly strain-free grains, grains with inhomogeneous strains, as well as twinning nucleated in the shoulder region of the boule. The GDMS chemical analysis shows the contamination of Ga at a level of 3900 ppb, atomic. The low temperature PL measurement exhibits the characteristic emissions of a Ga-doped sample. The Hall measurements show a resistivity of 1 x l0(exp 7) ohm-cm at room temperature to 3 x 10(exp 9) ohm-cm at 78K with the respective hole and electron concentration of 1.7 x 10(exp 9) cm(exp -3) and 3.9 x 10(exp 7) cm(exp -3) at room temperature.

The influence of point defects on the thermal conductivity of AlN crystals

NASA Astrophysics Data System (ADS)

Rounds, Robert; Sarkar, Biplab; Alden, Dorian; Guo, Qiang; Klump, Andrew; Hartmann, Carsten; Nagashima, Toru; Kirste, Ronny; Franke, Alexander; Bickermann, Matthias; Kumagai, Yoshinao; Sitar, Zlatko; Collazo, Ramón

2018-05-01

The average bulk thermal conductivity of free-standing physical vapor transport and hydride vapor phase epitaxy single crystal AlN samples with different impurity concentrations is analyzed using the 3ω method in the temperature range of 30-325 K. AlN wafers grown by physical vapor transport show significant variation in thermal conductivity at room temperature with values ranging between 268 W/m K and 339 W/m K. AlN crystals grown by hydride vapor phase epitaxy yield values between 298 W/m K and 341 W/m K at room temperature, suggesting that the same fundamental mechanisms limit the thermal conductivity of AlN grown by both techniques. All samples in this work show phonon resonance behavior resulting from incorporated point defects. Samples shown by optical analysis to contain carbon-silicon complexes exhibit higher thermal conductivity above 100 K. Phonon scattering by point defects is determined to be the main limiting factor for thermal conductivity of AlN within the investigated temperature range.

(PCG) Protein Crystal Growth HIV Reverse Transcriptase

NASA Technical Reports Server (NTRS)

1992-01-01

HIV Reverse Transcriptase crystals grown during the USML-1 (STS-50) mission using Commercial Refrigerator/Incubator Module (CR/IM) at 4 degrees C and the Vapor Diffusion Apparatus (VDA). Reverse transcriptase is an enzyme responsible for copying the nucleic acid genome of the AIDS virus from RNA to DNA. Studies indicated that the space-grown crystals were larger and better ordered (beyond 4 angstroms) than were comparable Earth-grown crystals. Principal Investigators were Charles Bugg and Larry DeLucas.

Growth, structural, spectral, optical, and thermal studies on amino acid based new NLO single crystal: L-phenylalanine-4-nitrophenol.

PubMed

Prakash, M; Lydia Caroline, M; Geetha, D

2013-05-01

A new organic nonlinear optical single crystal, L-phenylalanine-4-nitrophenol (LPAPN) belonging to the amino acid group has been successfully grown by slow evaporation technique. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. FT-IR spectrum was recorded to identify the presence of functional group and molecular structure was confirmed by NMR spectrum. Thermal strength of the grown crystal has been studied using TG-DTA analyses. The grown crystals were found to be transparent in the entire visible region. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm. Copyright © 2013 Elsevier B.V. All rights reserved.

Crystal Growth of ZnSe and Related Ternary Compound Semiconductors by Vapor Transport

NASA Technical Reports Server (NTRS)

2003-01-01

The objective of the project is to determine the relative contributions of gravity-driven fluid flows to the compositional distribution, incorporation of impurities and defects, and deviation from stoichiometry observed in the crystals grown by vapor transport as results of buoyancy-driven convection and growth interface fluctuations caused by irregular fluid-flows. ZnSe and related ternary compounds, such as ZnSeS and ZnSeTe, were grown by vapor transport technique with real time in situ non-invasive monitoring techniques. The grown crystals were characterized extensively to correlate the grown crystal properties with the growth conditions. Significant effects of gravity vector orientation on the growth crystal morphology and point defect distribution were observed.

van der Waals epitaxy of SnS film on single crystal graphene buffer layer on amorphous SiO2/Si

NASA Astrophysics Data System (ADS)

Xiang, Yu; Yang, Yunbo; Guo, Fawen; Sun, Xin; Lu, Zonghuan; Mohanty, Dibyajyoti; Bhat, Ishwara; Washington, Morris; Lu, Toh-Ming; Wang, Gwo-Ching

2018-03-01

Conventional hetero-epitaxial films are typically grown on lattice and symmetry matched single crystal substrates. We demonstrated the epitaxial growth of orthorhombic SnS film (∼500 nm thick) on single crystal, monolayer graphene that was transferred on the amorphous SiO2/Si substrate. Using X-ray pole figure analysis we examined the structure, quality and epitaxy relationship of the SnS film grown on the single crystal graphene and compared it with the SnS film grown on commercial polycrystalline graphene. We showed that the SnS films grown on both single crystal and polycrystalline graphene have two sets of orientation domains. However, the crystallinity and grain size of the SnS film improve when grown on the single crystal graphene. Reflection high-energy electron diffraction measurements show that the near surface texture has more phases as compared with that of the entire film. The surface texture of a film will influence the growth and quality of film grown on top of it as well as the interface formed. Our result offers an alternative approach to grow a hetero-epitaxial film on an amorphous substrate through a single crystal graphene buffer layer. This strategy of growing high quality epitaxial thin film has potential applications in optoelectronics.

Effect of solvents on the bulk growth of 4-aminobenzophenone single crystals: A potential material for blue and green lasers

NASA Astrophysics Data System (ADS)

Natarajan, V.; Usharani, S.; Arivanandhan, M.; Anandan, P.; Hayakawa, Y.

2015-06-01

Although 4-aminobenzophenone (4-ABP) is the best derivative of benzophenone with 260 times higher second harmonic generation (SHG) efficiency than potassium dihydrogen phosphate (KDP), growth of high quality bulk crystal still remains a difficult task. In the present work, the effect of solvents on solubility and growth aspects of 4-ABP was investigated to grow inclusion free 4-ABP crystals. The growth processes were discussed based on solute-solvent interaction in two different growth media of ethyl acetate and ethanol. The growth rate and thereby solvent inclusions are relatively higher in ethyl acetate grown crystal than the crystal grown from ethanol. The structural, thermal and optical properties of 4-ABP crystals were studied. The enthalpy of 4-ABP melting process was estimated from differential thermal analysis. The optical transmission study shows that 4-ABP crystals grown from ethanol has high transparency compared to ethyl acetate grown sample due to solvent inclusion in the later crystal.

Crystal growth, structural, optical, mechanical and thermal properties of a new nonlinear optical single crystal: L-Ornithine monohydrochloride.

PubMed

Balakrishnan, T; Ramamurthi, K

2009-03-01

Amino acid family crystals exhibit excellent nonlinear optical and electro optical properties. l-Ornithine monohydrochloride single crystal, belongs to the amino acid group, was grown by the slow evaporation solution growth technique at room temperature. The grown crystals were characterized by single crystal and powder X-ray diffraction analysis, Fourier transform infrared (FTIR) spectroscopy, TGA, DTA and DSC analyses. UV-vis-NIR spectrum shows excellent transmission in the UV, visible and NIR region (300-1600nm). The mechanical properties of grown crystals were studied using Vickers microhardness tester. Its second harmonic generation efficiency was tested using Nd:YAG laser and is 1.25 times that of KDP.

Solid-state reaction kinetics of neodymium doped magnesium hydrogen phosphate system

NASA Astrophysics Data System (ADS)

Gupta, Rashmi; Slathia, Goldy; Bamzai, K. K.

2018-05-01

Neodymium doped magnesium hydrogen phosphate (NdMHP) crystals were grown by using gel encapsulation technique. Structural characterization of the grown crystals has been carried out by single crystal X-ray diffraction (XRD) and it revealed that NdMHP crystals crystallize in orthorhombic crystal system with space group Pbca. Kinetics of the decomposition of the grown crystals has been studied by non-isothermal analysis. The estimation of decomposition temperatures and weight loss has been made from the thermogravimetric/differential thermo analytical (TG/DTA) in conjuncture with DSC studies. The various steps involved in the thermal decomposition of the material have been analysed using Horowitz-Metzger, Coats-Redfern and Piloyan-Novikova equations for evaluating various kinetic parameters.

Synthesis, growth, structural, optical, luminescence, surface and HOMO LUMO analysis of 2-[2-(4-cholro-phenyl)-vinyl]-1-methylquinolinium naphthalene-2-sulfonate organic single crystals grown by a slow evaporation technique

NASA Astrophysics Data System (ADS)

Karthigha, S.; Kalainathan, S.; Maheswara Rao, Kunda Uma; Hamada, Fumio; Yamada, Manabu; Kondo, Yoshihiko

2016-02-01

Single crystals of 2-[2-(4-cholro-phenyl)-vinyl]-1-methylquinolinium naphthalene-2-sulfonate (4CLNS) were grown by a slow evaporation technique. The formation of molecule was confirmed from 1H NMR and FTIR analysis. The confirmation of crystal structure was done by single crystal XRD and atomic packing of grown crystal was identified. The grown single crystal crystallized in triclinic structure with centrosymmetric space group P-1. The crystalline nature of the synthesised material was recorded by powder XRD. The optical absorption properties of the grown crystals were analyzed by UV-vis spectral studies. The thermal behaviour of the title material has been studied by TG/DTA analysis which revealed the stability of the compound till its melting point 276.7 °C. The third order nonlinear optical property of 4CLNS was investigated in detail by Z scan technique and it confirms that the title crystal is suitable for photonic devices and NLO optical applications. Emissions at 519 nm in green region of the EM spectrum were found by photoluminescence studies. The charge transfer occurring within the molecule is explained by the calculated HOMO and LUMO energies.

Growth and characterization of hexamethylenetetramine crystals grown from solution

NASA Astrophysics Data System (ADS)

Babu, B.; Chandrasekaran, J.; Balaprabhakaran, S.

2014-06-01

Organic nonlinear optical single crystals of hexamethylenetetramine (HMT; 10 × 10 × 5 mm3) were prepared by crystallization from methanol solution. The grown crystals were subjected to various characterization techniques such as single crystal XRD, powder XRD, UV-Vis and electrical studies. Single crystal XRD analysis confirmed the crystalline structure of the grown crystals. Their crystalline nature was also confirmed by powder XRD technique. The optical transmittance property was identified from UV-Vis spectrum. Dielectric measurements were performed as a function of frequency at different temperatures. DC conductivity and photoconductivity studies were also carried out for the crystal. The powder second harmonic generation efficiency (SHG) of the crystal was measured using Nd:YAG laser and the efficiency was found to be two times greater than that of potassium dihydrogen phosphate (KDP).

Protein Crystals Grown in Space

NASA Technical Reports Server (NTRS)

2000-01-01

A collage of protein and virus crystals, many of which were grown on the U.S. Space Shuttle or Russian Space Station, Mir. The crystals include the proteins canavalin; mouse monoclonal antibody; a sweet protein, thaumatin; and a fungal protease. Viruses are represented here by crystals of turnip yellow mosaic virus and satellite tobacco mosaic virus. The crystals are photographed under polarized light (thus causing the colors) and range in size from a few hundred microns in edge length up to more than a millimeter. All the crystals are grown from aqueous solutions and are useful for X-ray diffraction analysis. Credit: Dr. Alex McPherson, University of California, Irvine.

Factors affecting the morphology of isocitrate lyase crystals

NASA Technical Reports Server (NTRS)

Demattei, Robert C.; Feigelson, Robert S.; Weber, Patricia C.

1992-01-01

Isocitrate lyase crystals have been grown by the hanging drop vapor equilibration method in both 1-g and microgravity and by vapor equilibrium in small capillaries. The crystal morphologies obtained have ranged from dendritic to 'octagonal' prisms. Theoretical evaporation models have been applied to these growth regimes. The results of these analyses along with other experimental results, indicate the factors which must be controlled to produce good growth morphologies.

Optical properties and refractive indices of Gd3Al2Ga3O12:Ce3+ crystals

NASA Astrophysics Data System (ADS)

Kozlova, N. S.; Busanov, O. A.; Zabelina, E. V.; Kozlova, A. P.; Kasimova, V. M.

2016-05-01

Crystals of cerium-doped gadolinium-gallium-aluminum garnet have been grown by the Czochralski method. The transmission and reflection spectra of these crystals in the wavelength range of 250-800 nm have been obtained by optical spectroscopy. Refractive indices are calculated based on the measured Brewster angles, the experimental results are approximated using the Cauchy equation, and a dispersion dependence is obtained.

Growth and laser properties of Yb : Ca 4YO(BO 3) 3 crystal

NASA Astrophysics Data System (ADS)

Zhang, Huaijin; Meng, Xianlin; Zhu, Li; Wang, Pu; Liu, Xuesong; Cheng, Ruiping; Dawes, Judith; Dekker, Peter; Zhang, Shaojun; Sun, Lianke

1999-04-01

Yb : Ca 4YO(BO 3) 3 (Yb : YCOB) crystal has been grown by the Czochralski method. The absorption and fluorescence spectra have been measured. The green luminescence is also observed. The output laser at 1032 nm has been demonstrated pumped by laser diode (LD) at 976.4 nm.

DOE Office of Scientific and Technical Information (OSTI.GOV)

S. K. Kushwaha; Pletikosic, I.; Liang, T.

A long-standing issue in topological insulator research has been to find a bulk single crystal material that provides a high quality platform for characterizing topological surface states without interference from bulk electronic states. This material would ideally be a bulk insulator, have a surface state Dirac point energy well isolated from the bulk valence and conduction bands, display quantum oscillations from the surface state electrons, and be growable as large, high quality bulk single crystals. Here we show that this materials obstacle is overcome by bulk crystals of lightly Sn-doped Bi 1.1Sb 0.9Te 2S grown by the Vertical Bridgeman method.more » We characterize Sn-BSTS via angle-resolved photoemission spectroscopy, scanning tunneling microscopy, transport studies, X-ray diffraction, and Raman scattering. We present this material as a high quality topological insulator that can be reliably grown as bulk single crystals and thus studied by many researchers interested in topological surface states.« less

Crystal Growth of CdTe by Gradient Freeze in Universal Multizone Crystallizator (UMC)

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Lehoczky, S. L.; Li, C.; Knuteson, D.; Raghothamachar, B.; Dudley, M.; Szoke, J.; Barczy, P.

2004-01-01

In the case of unsealed melt growth of an array of II-VI compounds, namely, CdTe, CdZnTe and ZnSe, there is a tremendous amount of experimental data describing the correlations between melt conditions and crystal quality. The results imply that the crystallinity quality can be improved if the melt was markedly superheated or long-time held before growth. It is speculated that after high superheating the associated complex dissociate and the spontaneous nucleation is retarded. In this study, crystals of CdTe were grown from melts which have undergone different thermal history by the unseeded gradient freeze method using the Universal Multizone Crystallizator (UMC). The effects of melt conditions on the quality of grown crystal were studied by various characterization techniques, including Synchrotron White Beam X-ray Topography (SWSXT), infrared microscopy, chemical analysis by glow discharge mass spectroscopy (GDMS), electrical conductivity and Hall measurements.

A Comparison of Point Defects in Cd 1-xZn xTe 1-ySe y Crystals Grown by Bridgman and Traveling Heater Methods

DOE PAGES

Gul, R.; Roy, U. N.; Camarda, G. S.; ...

2017-03-28

In this study, the properties of point defects in Cd 1–xZn xTe 1–ySe y (CZTS) radiation detectors are characterized using deep-level transient spectroscopy and compared between materials grown using two different methods, the Bridgman method and the traveling heater method. The nature of the traps was analyzed in terms of their capture cross-sections and trap concentrations, as well as their effects on the measured charge-carrier trapping and de-trapping times, and then compared for the two growth techniques. The results revealed that Se addition to CdZnTe can reduce the V Cd – concentration. In Travelling Heater Method (THM) and Bridgman Methodmore » (BM) grown CZTS detectors, besides a few similarities in the shallow and medium energy traps, there were major differences in the deep traps. It was observed that the excess-Te and lower growth-temperature conditions in THM-grown CZTS led to a complete compensation of V Cd – and two additional traps (attributed to Te i – and Te Cd ++ appearing at around E v + 0.26 eV and E c – 0.78 eV, respectively). The 1.1-eV deep trap related to large Te secondary phases was a dominant trap in the BM-grown CZTS crystals. In addition to i-DLTS data, the effects of point defects induced due to different processing techniques on the detector's resistivity, spectral response to gammas, and μτ product were determined.« less

A Comparison of Point Defects in Cd 1-xZn xTe 1-ySe y Crystals Grown by Bridgman and Traveling Heater Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gul, R.; Roy, U. N.; Camarda, G. S.

In this study, the properties of point defects in Cd 1–xZn xTe 1–ySe y (CZTS) radiation detectors are characterized using deep-level transient spectroscopy and compared between materials grown using two different methods, the Bridgman method and the traveling heater method. The nature of the traps was analyzed in terms of their capture cross-sections and trap concentrations, as well as their effects on the measured charge-carrier trapping and de-trapping times, and then compared for the two growth techniques. The results revealed that Se addition to CdZnTe can reduce the V Cd – concentration. In Travelling Heater Method (THM) and Bridgman Methodmore » (BM) grown CZTS detectors, besides a few similarities in the shallow and medium energy traps, there were major differences in the deep traps. It was observed that the excess-Te and lower growth-temperature conditions in THM-grown CZTS led to a complete compensation of V Cd – and two additional traps (attributed to Te i – and Te Cd ++ appearing at around E v + 0.26 eV and E c – 0.78 eV, respectively). The 1.1-eV deep trap related to large Te secondary phases was a dominant trap in the BM-grown CZTS crystals. In addition to i-DLTS data, the effects of point defects induced due to different processing techniques on the detector's resistivity, spectral response to gammas, and μτ product were determined.« less

Isolation, purification, crystallization, and preliminary X-ray diffraction study of the crystals of HU protein from M. gallisepticum

NASA Astrophysics Data System (ADS)

Nikolaeva, A. Yu.; Timofeev, V. I.; Boiko, K. M.; Korzhenevskii, D. A.; Rakitina, T. V.; Dorovatovskii, P. V.; Lipkin, A. V.

2015-11-01

HU proteins are involved in bacterial DNA and RNA repair. Since these proteins are absent in cells of higher organisms, inhibitors of HU proteins can be used as effective and safe antibiotics. The crystallization conditions for the M. gallisepticum HU protein were found and optimized by the vapor-diffusion method. The X-ray diffraction data set was collected to 2.91 Å resolution from the crystals grown by the vapor-diffusion method on a synchrotron source. The crystals of the HU protein belong to sp. gr. P41212 and have the following unit-cell parameters: a = b = 97.94 Å, c = 77.92 Å, α = β = γ = 90°.

Growth, structural, optical and surface analysis of piperazinium tartrate: A NLO single crystal

NASA Astrophysics Data System (ADS)

Gupta, Apurva; Raseel Rahman M., K.; Nair, Lekha

2018-05-01

Single crystal of piperazinium tartrate (PPZT) was grown by the slow evaporation solution growth technique at room temperature. Crystallinity of grown crystal was examined by powder X-ray diffraction. High transparency and wide band gap were observed in the UV-Visible spectroscopic studies. Intense and broad emissions were observed in the blue region, as that is indicated by photoluminescence spectroscopy. The quality of the grown PPZT single crystals were analyzed by the etching studies using the water as the etchant.

Oxygen-induced recombination centers in as-grown Czochralski silicon crystals

NASA Technical Reports Server (NTRS)

Nauka, K.; Gatos, H. C.; Lagowski, J.

1983-01-01

Simultaneous quantitative microprofiles of the interstitial oxygen concentration and of the excess carrier lifetime are obtained in Czochralski-grown Si crystals employing double laser absorption scanning. It is found that oxygen concentration maxima and minima along the crystal growth direction coincide with lifetime minima and maxima, respectively. Another finding is that the magnitude of oxygen-induced lifetime changes increases dramatically in going from the center to the periphery of the crystal. The findings discussed imply that 'as-grown' oxygen precipitates figure in lifetime-limiting processes.

Drop deployment system for crystal growth apparatus

NASA Technical Reports Server (NTRS)

Rhodes, Percy (Inventor); Snyder, Robert S. (Inventor); Pusey, Marc L. (Inventor)

1990-01-01

A crystal growth apparatus is presented. It utilizes a vapor diffusion method for growing protein crystals, and particularly such an apparatus wherein a ball mixer is used to mix the fluids that form a drop within which crystals are grown. Particular novelty of this invention lies in utilizing a ball mixer to completely mix the precipitate and protein solutions prior to forming the drop. Additional novelty lies in details of construction of the vials, the fluid deployment system, and the fluid storage system of the preferred embodiment.

Dielectric and domain studies on Fe doped KNbO3 single crystal

NASA Astrophysics Data System (ADS)

Shamkuwar, Sanjaykumar H.; Patil, Naresh M.; Korde, Vivek B.; Pradnyakar, Namrata V.

2018-05-01

Synthesis of Fe doped KNbO3 single crystals by flux method is reported here. The effect of Fe-doping on phase transition temperatures of KNbO3 single crystals was investigated using dielectric studies. The phase transition temperatures were found to be 225°C and 425°C which almost same as reported by others. The domain studies were carried out using metallurgical microscope and it shows the presence of 60° and 90° domains in the grown crystals.

Bulk crystal growth of Ga2O3

NASA Astrophysics Data System (ADS)

Kuramata, Akito; Koshi, Kimiyoshi; Watanabe, Shinya; Yamaoka, Yu; Masui, Takekazu; Yamakoshi, Shigenobu

2018-02-01

This paper describes the bulk crystal growth of β-Ga2O3 using edge-defined film-fed growth (EFG) process. We first describe the method of the crystal growth and show that large-size crystal with width of up to 6 inch can be grown. Then, we discuss the way to control electrical properties. In the discussion, we give some experimental results of residual impurity measurement, intentional doping using Si and Sn for n-type doping and Fe for insulating doping.

Liquid-liquid diffusion crystallization improves the X-ray diffraction of EndoS, an endo-β-N-acetylglucosaminidase from Streptococcus pyogenes with activity on human IgG.

PubMed

Trastoy, Beatriz; Lomino, Joseph V; Wang, Lai Xi; Sundberg, Eric J

2013-12-01

Endoglycosidase S (EndoS) is an enzyme secreted by Streptococcus pyogenes that specifically hydrolyzes the β-1,4-di-N-acetylchitobiose core glycan on immunoglobulin G (IgG) antibodies. One of the most common human pathogens and the cause of group A streptococcal infections, S. pyogenes secretes EndoS in order to evade the host immune system by rendering IgG effector mechanisms dysfunctional. On account of its specificity for IgG, EndoS has also been used extensively for chemoenzymatic synthesis of homogeneous IgG glycoprotein preparations and is being developed as a novel therapeutic for a wide range of autoimmune diseases. The structural basis of its enzymatic activity and substrate specificity, however, remains unknown. Here, the purification and crystallization of EndoS are reported. Using traditional hanging-drop and sitting-drop vapor-diffusion crystallization, crystals of EndoS were grown that diffracted to a maximum of 3.5 Å resolution but suffered from severe anisotropy, the data from which could only be reasonably processed to 7.5 Å resolution. When EndoS was crystallized by liquid-liquid diffusion, it was possible to grow crystals with a different space group to those obtained by vapor diffusion. Crystals of wild-type endoglycosidase and glycosynthase constructs of EndoS grown by liquid-liquid diffusion diffracted to 2.6 and 1.9 Å resolution, respectively, with a greatly diminished anisotropy. Despite extensive efforts, the failure to reproduce these liquid-liquid diffusion-grown crystals by vapor diffusion suggests that these crystallization methods each sample a distinct crystallization space.

Investigation on growth and macro-defects of Er3+-doped BaY2F8 laser crystal

NASA Astrophysics Data System (ADS)

Wang, Shuai; Ruan, Yongfeng; Tsuboi, Taiju; Zhang, Shouchao; Wang, Youfa; Tong, Hongshuang

2013-08-01

Large BaY2F8 and Er3+-doped BaY2F8 single crystals were grown by the temperature gradient method. Three kinds of macro-defects were found in BaY2F8 single crystals. These macro-defects include cracks, growth striations and straight pipes. The morphologies and distribution regularities of these macro-defects were observed and studied using a solid polarization microscope. The formation mechanisms and the methods of eliminating these defects were discussed.

Optical, Fluorescence with quantum analysis of hydrazine (1, 3- Dinitro Phenyl) by DFT and Ab initio approach

NASA Astrophysics Data System (ADS)

Cecily Mary Glory, D.; Sambathkumar, K.; Madivanane, R.; Velmurugan, G.; Gayathri, R.; Nithiyanantham, S.; Venkatachalapathy, M.; Rajkamal, N.

2018-07-01

Experimental and computational study of molecular structure, vibrational and UV-spectral analysis of Hydrazine (1, 3- Dinitrophenyl) (HDP) derivatives. The crystal was grown by slow cooling method and the crystalline perfection of single crystals was evaluated by high resolution X-ray diffractometry (HRXRD) using a multicrystal X-ray diffractometer. Fluorescence, FT-IR and FT-Raman spectra of HDP crystal were recorded. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) followed by scaled quantum force field methodology (SQMFF). NMR studies have confirmed respectively the crystal structure and functional groups of the grown crystal. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) result complements the experimental findings. The calculated MESP, UV, HOMO-LUMO energies show that charge transfer done within the molecule. And various thermodynamic parameters are studied. Fukui determines the local reactive site of electrophilic, nucleophilic, descriptor.

Growth and anisotropic thermal properties of biaxial Ho:YAlO3 crystal

NASA Astrophysics Data System (ADS)

Dong, Qin; Zhao, Guangjun; Chen, Jianyu; Ding, Yuchong; Zhao, Chengchun

2010-07-01

Ho:YAlO3 (YAP) crystal with large size and good optical quality has been grown by the Czochralski method. Thermal properties of the as-grown Ho:YAP crystal have been investigated by measuring the temperature-dependent, anisotropic thermal expansion, specific heat, thermal diffusion, and thermal conductivity. The results show that Ho:YAP crystal possesses a large anisotropic thermal expansion and good thermal conductivity. The calculated average thermal expansion coefficients along a, b, and c axis are αa=9.18×10-6/K, αb=1.94×10-6/K, and αc=7.61×10-6/K from 293.15 to 770.15 K. The thermal conductivities along a, b, and c axis are up to 11.6, 9.9, and 12.3 W m-1 K-1 at 298.15 K. Compared with Ho: Y3Al5O12 (YAG), Ho:YAP crystal has a larger thermal conductivity along a axis from 298.15 to 568.15 K.

Sn-doped Bi 1.1Sb 0.9Te 2S bulk crystal topological insulator with excellent properties

DOE PAGES

S. K. Kushwaha; Pletikosic, I.; Liang, T.; ...

2016-04-27

A long-standing issue in topological insulator research has been to find a bulk single crystal material that provides a high quality platform for characterizing topological surface states without interference from bulk electronic states. This material would ideally be a bulk insulator, have a surface state Dirac point energy well isolated from the bulk valence and conduction bands, display quantum oscillations from the surface state electrons, and be growable as large, high quality bulk single crystals. Here we show that this materials obstacle is overcome by bulk crystals of lightly Sn-doped Bi 1.1Sb 0.9Te 2S grown by the Vertical Bridgeman method.more » We characterize Sn-BSTS via angle-resolved photoemission spectroscopy, scanning tunneling microscopy, transport studies, X-ray diffraction, and Raman scattering. We present this material as a high quality topological insulator that can be reliably grown as bulk single crystals and thus studied by many researchers interested in topological surface states.« less

Reduction of Defects in Germanium-Silicon

NASA Technical Reports Server (NTRS)

Szofran, Frank R.; Benz, K. W.; Cobb, Sharon D.; Croell, Arne; Dold, Peter; Kaiser, Natalie; Motakef, Shariar; Schweizer, Marcus; Volz, Martin P.; Vujisic, Ljubomir

2001-01-01

Crystals grown without being in contact with a container have superior quality to otherwise similar crystals grown in direct contact with a container, especially with respect to impurity incorporation, formation of dislocations, and residual stress in the crystals. In addition to float-zone processing, detached Bridgman growth, although not a completely crucible-free method, is a promising tool to improve crystal quality. It does not suffer from the size limitations of float zoning and the impact of thermocapillary convection on heat and mass transport is expected to be negligible. Detached growth has been observed frequently during (micro)g experiments. Considerable improvements in crystalline quality have been reported for these cases. However, neither a thorough understanding of the process nor a quantitative assessment of the quality of these improvements exists. This project will determine the means to reproducibly grow Pepsi alloys in a detached mode and seeks to compare processing-induced defects in Bridgman, detached-Bridgman, and floating-zone growth configurations in Pepsi crystals (Si less or = 10 at%) up to 20mm in diameter.

Thermal, Dielectric Studies on Pure and Amino Acid L-Glutamic Acid, L-Histidine L-Valine Doped Potassium Dihydrogen Phosphate Single Crystals

NASA Astrophysics Data System (ADS)

Kumaresan, P.; Babu, S. Moorthy; Anbarasan, P. M.

Amino acids (L-Glutamic acid, L-Histidine, L-Valine) doped potassium dihydrogen phosphate crystals were grown by the solution growth technique. Slow cooling as well as slow evaporation methods were employed to grow these crystals. The concentration of dopants in the mother solution was varied from 0.1 mole % to 10 mole %. The solubility data for all dopant concentrations were determined. The variation in pH and the corresponding habit modification of the grown crystals were characterized with UV - VIS, FT-IR and SHG trace elements, and dielectric studies reveal slight distortion of lattice parameter for the heavily doped KDP crystals. TGA-DTA studies reveal good thermal stability. The dopants increase the hardness value of the material, which also depends on the concentration of the dopants. Amino acids doping improved the NLO properties. The detailed results on the spectral parameters, habit modifications and constant values will be presented.

A strategic approach to physico-chemical analysis of bis (thiourea) lead chloride - A reliable semi-organic nonlinear optical crystal

NASA Astrophysics Data System (ADS)

Rajagopalan, N. R.; Krishnamoorthy, P.; Jayamoorthy, K.

2017-03-01

Good quality crystals of bis thiourea lead chloride (BTLC) have been grown by slow evaporation method from aqueous solution. Orthorhombic structure and Pna21 space group of the crystals have been identified by single crystal X-ray diffraction. Studies on nucleation kinetics of grown BTLC has been carried out from which meta-stable zone width, induction period, free energy change, critical radius, critical number and growth rate have been calculated. The experimental values of interfacial surface energy for the crystal growth process have been compared with theoretical models. Ultra violet transmittance studies resulted in a high transmittance and wide band gap energy suggested the required optical transparency of the crystal. The second harmonic generation (SHG) and phase matching nature of the crystal have been justified by Kurtz-Perry method. The SHG nature of the crystal has been further attested by the higher values of theoretical hyper polarizability. The dielectric nature of the crystals at different temperatures with varying frequencies has been thoroughly studied. The activation energy values of the electrical process have been calculated from ac conductivity study. Solid state parameters including valence electron plasma energy, Penn gap, Fermi energy and polarisability have been unveiled by theoretical approach and correlated with the crystal's SHG efficiency. The values of hardness number, elastic stiffness constant, Meyer's Index, minimum level of indentation load, load dependent constant, fracture toughness, brittleness index and corrected hardness obtained from Vicker's hardness test clearly showed that the BTLC crystal has good mechanical stability required for NLO device fabrication.

Magnetic properties of LCMO deposited films

NASA Astrophysics Data System (ADS)

Park, Seung-Iel; Jeong, Kwang Ho; Cho, Young Suk; Kim, Chul Sung

2002-04-01

La-Ca-Mn-O films were deposited with various thickness (500, 1000 and 1500°C) by RF-magnetron sputtering at 700°C and by the spin coating of sol-gel method at 400°C on LaAlO 3(1 0 0) and Si(1 0 0) single-crystal substrates. The crystal structure and chemical composition of the film grown by RF sputtering method were orthorhombic and La 0.89Ca 0.11MnO 3, respectively, while the film prepared by sol-gel spin coating was cubic with La 0.7Ca 0.3MnO 3. The temperature dependence of the resistance for the film grown by RF sputtering method with the thickness of 1000°C shows that a semiconductor-metal transition occurs at 242 K. The relative maximum magnetoresistance is about 273% at 226 K.

Crystal growth by Bridgman and Czochralski method of the ferromagnetic quantum critical material YbNi4P2

NASA Astrophysics Data System (ADS)

Kliemt, K.; Krellner, C.

2016-09-01

The tetragonal YbNi4P2 is one of the rare examples of compounds that allow the investigation of a ferromagnetic quantum critical point. We report in detail on two different methods which have been used to grow YbNi4P2 single crystals from a self-flux. The first, a modified Bridgman method, using a closed crucible system yields needle-shaped single crystals oriented along the [001]-direction. The second method, the Czochralski growth from a levitating melt, yields large single crystals which can be cut in any desired orientation. With this crucible-free method, samples without flux inclusions and a resistivity ratio at 1.8 K of RR1.8K = 17 have been grown.

Relaxor properties of barium titanate crystals grown by Remeika method

NASA Astrophysics Data System (ADS)

Roth, Michel; Tiagunov, Jenia; Dul'kin, Evgeniy; Mojaev, Evgeny

2017-06-01

Barium titanate (BaTiO3, BT) crystals have been grown by the Remeika method using both the regular KF and mixed KF-NaF (0.6-0.4) solvents. Typical acute angle "butterfly wing" BT crystals have been obtained, and they were characterized using x-ray diffraction, scanning electron microscopy (including energy dispersive spectroscopy), conventional dielectric and acoustic emission methods. A typical wing has a triangular plate shape which is up to 0.5 mm thick with a 10-15 mm2 area. The plate has a (001) habit and an atomically smooth outer surface. Both K+ and F- solvent ions are incorporated as dopants into the crystal lattice during growth substituting for Ba2+ and O2- ions respectively. The dopants' distribution is found to be inhomogeneous, their content being almost an order of magnitude higher (up to 2 mol%) at out surface of the plate relatively to the bulk. A few μm thick surface layer is formed where a multidomain ferroelectric net is confined between two≤1 μm thick dopant-rich surfaces. The layer as a whole possess relaxor ferroelectric properties, which is apparent from the appearance of additional broad maxima, Tm, in the temperature dependence of the dielectric permittivity around the ferroelectric phase transition. Intense acoustic emission responses detected at temperatures corresponding to the Tm values allow to observe the Tm shift to lower temperatures at higher frequencies, or dispersion, typical for relaxor ferroelectrics. The outer surface of the BT wing can thus serve as a relaxor thin film for various electronic application, such as capacitors, or as a substrate for BT-based multiferroic structure. Crystals grown from KF-NaF fluxes contain sodium atoms as an additional impurity, but the crystal yield is much smaller, and while the ferroelectric transition peak is diffuse it does not show any sign of dispersion typical for relaxor behavior.

Growth and characterization of a new nonlinear optical organic crystal: 2,4,6-Trimethylacetanilide

NASA Astrophysics Data System (ADS)

Upadhyaya, V.; Prabhu, Sharada G.

2015-09-01

A new nonlinear optical organic material, 2,4,6-trimethylacetanilide (246TMAA), also known as N-[2,4,6- trimethylphenyl]acetamide, has been synthesized and grown as a single crystal by the slow evaporation technique by organic solvents. The grown crystals have been characterized by morphology study. The crystals are prismatic. Surface examination shows granular dendritic pattern in optical micrograph. The Scanning Electron Micrograph shows the layered growth of the crystal. The Differential Scanning Calorimeter plot shows no phase change until melting point (219°C). The density of the crystals is 1.1g/cc and the crystals are soft. The crystals are transparent in the visible region and in the ultra-violet region till 280 nm. 246TMAA crystallizes with 2 molecules in a monoclinic unit cell in the noncentrosymmetric point group m, space group Pn. Refractive indices of this optically biaxial crystal along the three crystallophysical axes have been measured at 633 nm. The optical second harmonic generation efficiency of the crystal at 1064 nm is about half that of the urea crystal, measured by powder method using Nd:YAG laser. The results show that the 246TMAA crystal can efficiently be used for up-conversion of infrared radiation into visible green light. The powder X-ray diffraction spectrum of the crystal has been obtained.

Spectroscopic and quantum chemical perspectives on 2-amino 5-methylpyridinium 4-nitrobenzoate - An organic single crystals for optoelectronics device applications

NASA Astrophysics Data System (ADS)

Gandhimathi, A.; Karunakaran, R. T.; Kumaran, A. Elakkina; Prabahar, S.

2018-07-01

In this work, an optical quality single crystals of 2-amino 5-methylpyridinium 4-nitrobenzoate (2A5MPNB) were grown by slow evaporation solution growth technique using methanol as a solvent. The phases and functional groups of 2A5MPNB have been confirmed through powder X-ray diffraction and Fourier transform infrared (FTIR) studies, respectively. The optical transmittance window and the lower cut-off wavelength of the 2A5MPNB have been identified by UV-Vis-NIR studies. Dielectric and photoconductivity studies were also performed for the grown crystals. In order to analyze the mechanical strength Vickers hardness studies were taken for the grown crystal. The thermal behaviour was investigated by TG/DTA studies. NLO and laser damage properties were explored using Nd:YAG laser. Moreover, the quantum chemical calculations on 2A5MPNB have been performed by density functional theory (DFT) calculations using the B3LYP method with 6-311++G(d,p) basis set. The predicted first hyperpolarizability is found to be 14.45 times greater than that of urea and suggests that the title compound could be an attractive material for nonlinear optical applications.

Synthesis, crystal growth and characterization of bioactive material: 2- Amino-1H-benzimidazolium pyridine-3-carboxylate single crystal- a proton transfer molecular complex

NASA Astrophysics Data System (ADS)

Fathima, K. Saiadali; Kavitha, P.; Anitha, K.

2017-09-01

The 1:1 molecular adducts 2- Amino-1H-benzimidazolium pyridine-3-carboxylate (2ABPC) was synthesized and grown as single crystal where 2-aminobenzimidazole (ABI) acts as a donor and nicotinic acid (NA) acts as an acceptor. The presence of proton and carbon were predicted using 1H and 13C NMR spectral analysis. The molecular structure of the crystal was elucidated by subjecting the grown crystals to the single crystal x-ray diffraction analysis and was refined by full matrix least-squares method to R = 0.038 for 2469 reflections. The vibrational modes of functional group have been studied using FTIR and Raman spectroscopic analysis. The UV-Vis spectrum exhibited a visible band at 246 nm for 2ABPC due to the nicotinate anion of the molecule. Further, the antimicrobial activity of 2ABPC complex against B. subtilis, klebsiella pneumonia, Pseudomonas eruginos and E. coli pathogens was investigated. Minimum Inhibitory Concentration (MIC) for this crystal was obtained using UV spectrometer against MRSA pathogen. It was found that the benzimidazole with aminogroup at position 2 increases the general antimicrobial activities of 2ABPC crystal.

Growth and piezoelectric properties of Ca3Nb(Al0.5Ga0.5)3Si2O14 crystals with langasite structure

NASA Astrophysics Data System (ADS)

Xiong, Kainan; Zheng, Yanqing; Tu, Xiaoniu; Jiang, Bohan; Cao, Shuoliang; Shi, Erwei

2017-06-01

Piezoelectric crystals Ca3Nb(Al0.5Ga0.5)3Si2O14 (CNAGS) with langasite structure have been successfully grown by Czochralski method. In this work, the crystal structure, quality, chemical composition, piezoelectric properties, electric resistivity and optical properties of the as-grown crystals were characterized. The full width at half-maximum (FWHM) of the rocking curve of CNAGS was found to be 23″. The chemical compositions of CNAGS crystals are very close to that of initial compositions. At room temperature, the piezoelectric coefficients d11 and d14 of CNAGS crystals are 4.12 pC/N and -5.03 pC/N, and the electromechanical coupling coefficients k12 and k26 are also determined as 11.6% and 18.3%, respectively. The electric resistivity of as-growth crystal was found to be on the order of 2×108 Ω cm at 500 °C and 1×106 Ω cm at 800 °C. And the transmittances of CNAGS crystals were found to be over 80% in the wavelength range of 700-2700 nm.

Crystal growth, thermal and optical studies of semiorganic nonlinear optical material: L-lysine hydrochloride dihydrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalaiselvi, D.; Mohan Kumar, R.; Jayavel, R.

2008-07-01

Single crystals of L-lysine hydrochloride dihydrate (LLHCD), a nonlinear optical material, have been grown by slow cooling technique from its aqueous solution. LLHCD was found to be highly soluble in water. The grown crystals have been subjected to single crystal X-ray diffraction to confirm the structure and to estimate the lattice parameters. The vibrational structure of the molecule is elucidated from FTIR spectra. Thermal analysis revealed the thermal stability of the grown crystals. The optical transmittance spectrum shows that the material possesses good optical transparency in the entire visible region with a UV cut-off wavelength at 228 nm. The mechanicalmore » properties of the grown crystal have been studied using Vicker's microhardness test. The laser damage threshold of 52.25 MW/cm{sup 2} has been measured by irradiating Q-switched Nd:YAG laser (1064 nm)« less

Crystal growth and characterization of bulk Sb2Te3 topological insulator

NASA Astrophysics Data System (ADS)

Sultana, Rabia; Gurjar, Ganesh; Patnaik, S.; Awana, V. P. S.

2018-04-01

The Sb2Te3 crystals are grown using the conventional self flux method via solid state reaction route, by melting constituent elements (Sb and Te) at high temperature (850 °C), followed by slow cooling (2 °C/h). As grown Sb2Te3 crystals are analysed for various physical properties by x-ray diffraction (XRD), Raman Spectroscopy, Scanning Electron Microscopy (SEM) coupled with Energy Dispersive x-ray Spectroscopy (EDAX) and electrical measurements under magnetic field (6 Tesla) down to low temperature (2.5 K). The XRD pattern revealed the growth of synthesized Sb2Te3 sample along (00l) plane, whereas the SEM along with EDAX measurements displayed the layered structure with near stoichiometric composition, without foreign contamination. The Raman scattering studies displayed known ({{{{A}}}1{{g}}}1, {{{{E}}}{{g}}}2 and {{{{A}}}1{{g}}}2) vibrational modes for the studied Sb2Te3. The temperature dependent electrical resistivity measurements illustrated the metallic nature of the as grown Sb2Te3 single crystal. Further, the magneto—transport studies represented linear positive magneto-resistance (MR) reaching up to 80% at 2.5 K under an applied field of 6 Tesla. The weak anti localization (WAL) related low field (±2 Tesla) magneto-conductance at low temperatures (2.5 K and 20 K) has been analysed and discussed using the Hikami—Larkin—Nagaoka (HLN) model. Summarily, the short letter reports an easy and versatile method for crystal growth of bulk Sb2Te3 topological insulator (TI) and its brief physical property characterization.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hossain, M. Anwar; Center for Crystal Science and Technology, University of Yamanashi, Miyamae 7-32, Kofu, Yamanashi 400-8511; Tanaka, Isao

We studied thermoelectric properties of YB{sub 41}Si{sub 1.3} single crystals grown by the floating zone method. The composition of the grown crystal was confirmed by electron probe micro-analysis. We have determined the growth direction for the first time for these borosilicides, and discovered relatively large anisotropy in electrical properties. We measured the electrical resistivity and Seebeck coefficient along [510] (the growth direction) and [052] directions and we found that this crystal exhibits strong electrical anisotropy with a maximum of more than 8 times. An interesting layered structural feature is revealed along [510] with dense boron cluster layers and yttrium layers,more » with conductivity enhanced along this direction. We obtained 3.6 times higher power factor along [510] compared to that along [052]. Although the ZT of the present system is low, anisotropy in the thermoelectric properties of a boride was reported for the first time, and can be a clue in developing other boride systems also. - Graphical abstract: The growth direction ([510]) was determined for the first time in YB{sub 41}Si{sub 1.3} single crystals and revealed an interesting layered feature of boron clusters and metal atoms, along which the electrical conductivity and thermoelectric power factor was strongly enhanced. - Highlights: • We have grown YB{sub 41}Si{sub 1.3} single crystals by the floating zone method. • Growth direction of [510] determined for first time in REB{sub 41}Si{sub 1.2}. • Electrical resistivity was strongly anisotropic with possible enhancement along metal layers. • The obtained power factor along [510] is 3.6 times higher than that along [052].« less

Influence of carbon on the thermoluminescence and optically stimulated luminescence of α-Al2O3:C crystals

NASA Astrophysics Data System (ADS)

Yang, Xin-Bo; Li, Hong-Jun; Bi, Qun-Yu; Cheng, Yan; Tang, Qiang; Xu, Jun

2008-12-01

α-Al2O3:C crystal shows excellent thermoluminescence (TL) and optically stimulated luminescence (OSL) properties but the real role carbon plays in this crystal is still not clearly understood so far. In this work, α-Al2O3:C crystal doping with different amounts of carbon were grown by the temperature gradient technique, and TL and OSL properties of as-grown crystals were investigated. Additionally, a mechanism was proposed to explain the role of carbon in forming the TL and OSL properties of α-Al2O3:C. TL and OSL intensities of as-grown crystals increase with the increasing amount of carbon doping in the crystal, but no shift is found in the glow peak location at 465 K. As the amount of carbon doping in the crystals decreases, OSL decay rate becomes faster. With the increase in heating rate, the integral TL response of as-grown crystals decreases and glow peak shifts to higher temperatures. TL response decrease rate increases with the increasing amount of carbon doping in the crystals. All the TL and OSL response curves of as-grown crystals show linear-sublinear-saturation characteristic, and OSL dose response exhibits higher sensitivity and wider linear dose range than that of TL. The crystal doping with 5000 ppm carbon shows the best dosimetric properties. Carbon plays the role of a dopant in α-Al2O3:C crystal and four-valent carbon anions replace the two-valent anions of oxygen during the crystal growth process, and large amounts of oxygen vacancies were formed, which corresponds to the high absorption coefficient of F and F+ centers in the crystals.

Growth and physicochemical properties of organometallic (DL)-trithioureatartrato-O1,O2,O3-cadmium(II) single crystals

NASA Astrophysics Data System (ADS)

Sathyamoorthy, K.; Vinothkumar, P.; Irshad Ahamed, J.; Murali Manohar, P.; Priya, M.; Liu, Jinghe

2018-04-01

Single crystals of organometallic (DL)-trithioureatartrato-O1,O2,O3-cadmium(II) (TUDLC) have been grown from methanol solution by using the slow evaporation of solvent growth technique. The lattice structure and crystalline perfection have been determined by carrying out single crystal X-ray diffraction and high resolution X-ray diffraction measurements. The grown crystal was characterized thermally and mechanically by carrying out thermo-gravimetric and micro hardness measurements. The linear and nonlinear optical characterizations were made by carrying out optical transmittance, surface laser damage threshold, particle size-dependent second harmonic generation (SHG) efficiency and photo conductivity measurements. The grown crystal was electrically characterized by carrying out frequency-dependent dielectric measurements. Chemical etching study was also carried out and the dislocation density was estimated. Results obtained in the present study indicate that the grown TUDLC crystal is optically transparent with lower cut-off wavelength 304 nm, mechanically soft, thermally stable up to 101 °C and NLO active with SHG efficiency 2.13 (in KDP unit). The grown crystal is found to have considerably large size, good crystalline perfection, large specific heat capacity, higher surface laser damage threshold and negative photoconductivity.

Crystal growth and magneto-transport behavior of PdS1-δ

NASA Astrophysics Data System (ADS)

Cao, Lin; Lv, Yang-Yang; Chen, Si-Si; Li, Xiao; Zhou, Jian; Yao, Shu-Hua; Chen, Y. B.; Lu, Minghui; Chen, Yan-Feng

2018-04-01

PdS is theoretically proposed to novel topological material with eight-band fermions. Here, PdS1-δ crystals were successfully grown from KI as solvent by modified flux method. The single crystalline quality and compositional homogeneity of grown PdS1-δ are characterized by X-ray diffraction and energy dispersion spectroscopy. Temperature dependent electrical transport property of PdS1-δ demonstrates a semiconductor-like behavior. Analysis of temperature-dependent resistance indicates that there is variable-range-hopping behavior at low temperature. The clear negative MR of PdS1-δ single crystals is measured at the low temperature (<30 K), which may be ascribed to the interaction between conducting carriers and localized moments. however, the magneto-transport results have not shown the clues of topological feature of PdS.

Ground based experiments on the growth and characterization of L-Arginine Phosphate (LAP) crystals

NASA Technical Reports Server (NTRS)

Rao, S. M.; Cao, C.; Batra, A. K.; Lal, R. B.; Mookherji, T. K.

1991-01-01

L-Arginine Phosphate (LAP) is a new nonlinear optical material with higher efficiency for harmonic generation compared to KDP. Crystals of LAP were grown in the laboratory from supersaturated solutions by temperature lowering technique. Investigations revealed the presence of large dislocation densities inside the crystals which are observed to produce refractive index changes causing damage at high laser powers. This is a result of the convection during crystal growth from supersaturated solutions. It is proposed to grow these crystals in a diffusion controlled growth condition under microgravity environment and compare the crystals grown in space with those grown on ground. Physical properties of the solutions needed for modelling of crystal growth are also presented.

Investigation on the growth and characterization of 4-aminobenzophenone single crystal by the vertical dynamic gradient freeze technique

NASA Astrophysics Data System (ADS)

Prabhakaran, SP.; Ramesh Babu, R.; Sukumar, M.; Bhagavannarayana, G.; Ramamurthi, K.

2014-03-01

Growth of bulk single crystal of 4-Aminobenzophenone (4-ABP) from the vertical dynamic gradient freeze (VDGF) setup designed with eight zone furnace was investigated. The experimental parameters for the growth of 4-ABP single crystal with respect to the design of VDGF setup are discussed. The eight zones were used to generate multiple temperature gradients over the furnace, and video imaging system helped to capture the real time growth and solid-liquid interface. 4-ABP single crystal with the size of 18 mm diameter and 40 mm length was grown from this investigation. Structural and optical quality of grown crystal was examined by high resolution X-ray diffraction and UV-visible spectral analysis, respectively and the blue emission was also confirmed from the photoluminescence spectrum. Microhardness number of the crystal was estimated at different loads using Vicker's microhardness tester. The size and quality of single crystal grown from the present investigation are compared with the vertical Bridgman grown 4-ABP.

Temperature dependence of single-crystal elastic constants of flux-grown alpha-GaPO(4).

PubMed

Armand, P; Beaurain, M; Rufflé, B; Menaert, B; Papet, P

2009-06-01

The lattice parameter change with respect to temperature (T) has been measured using high-temperature powder X-ray diffraction techniques for high-temperature flux-grown GaPO(4) single crystals with the alpha-quartz structure. The lattice and the volume linear thermal expansion coefficients in the temperature range 303-1173 K were computed from the X-ray data. The percentage linear thermal expansions along the a and c axes at 1173 K are 1.5 and 0.51, respectively. The temperature dependence of the mass density rho of flux-grown GaPO(4) single crystals was evaluated using the volume thermal expansion coefficient alpha(V)(T) = 3.291 x 10(-5) - 2.786 x 10(-8) [T] + 4.598 x 10(-11)[T](2). Single-crystal high-resolution Brillouin spectroscopy measurements have been carried out at ambient pressure from 303 to 1123 K to determine the elastic constants C(IJ) of high-temperature flux-grown GaPO(4) material. The single-crystal elastic moduli were calculated using the sound velocities via the measured Brillouin frequency shifts Deltanu(B). These are, to our knowledge, the highest temperatures at which single-crystal elastic constants of alpha-GaPO(4) have been measured. Most of the room-temperature elastic constant values measured on flux-grown GaPO(4) material are higher than the ones found for hydrothermally grown GaPO(4) single crystals. The fourth-order temperature coefficients of both the Brillouin frequency shifts T(nuB)((n)) and the single-crystal elastic moduli T(C(IJ))((n)) were obtained. The first-order temperature coefficients of the C(IJ) are in excellent agreement with previous reports on low-temperature hydrothermally grown alpha-GaPO(4) single crystals, while small discrepancies in the higher-order temperature coefficients are observed. This is explained in terms of the OH content in the GaPO(4) network, which is an important parameter in the crystal thermal behavior.

Growth, nonlinear optical, thermal, dielectric and laser damage threshold studies of semiorganic crystal: monohydrate piperazine hydrogen phosphate.

PubMed

Krishnan, P; Gayathri, K; Bhagavannarayana, G; Gunasekaran, S; Anbalagan, G

2013-02-01

Monohydrate piperazine hydrogen phosphate (MPHP), a semi organic nonlinear optical material has been synthesized and single crystals were grown from aqueous solution by slow evaporation technique. Single crystal X-ray diffraction study on grown crystal reveals that they belong to monoclinic crystal system with space group P2(1)/c; (a=6.39Å; b=12.22Å; c=11.16Å; β=97.14°; V=864Å(3)). The structural perfection of the grown crystal was analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. FTIR spectrum confirms the presence of the functional groups in synthesized material. UV-Vis spectrum indicates that the crystal is transparent in the entire visible region with a lower cut off wavelength of 387 nm. The variation of dielectric properties of the grown crystal with respect to frequency has been investigated at different temperatures. Thermal analysis carried out on the MPHP crystal shows that the crystal is stable up to 135°C. Relative powder second harmonic generation efficiency tested by Kurtz-Perry powder technique, which was about 0.638 times that of Potassium dihydrogen phosphate. Copyright © 2012 Elsevier B.V. All rights reserved.

Self-Phase-Matched Second-Harmonic and White-Light Generation in a Biaxial Zinc Tungstate Single Crystal

PubMed Central

Osewski, Pawel; Belardini, Alessandro; Petronijevic, Emilija; Centini, Marco; Leahu, Grigore; Diduszko, Ryszard; Pawlak, Dorota A.; Sibilia, Concita

2017-01-01

Second-order nonlinear optical materials are used to generate new frequencies by exploiting second-harmonic generation (SHG), a phenomenon where a nonlinear material generates light at double the optical frequency of the input beam. Maximum SHG is achieved when the pump and the generated waves are in phase, for example through birefringence in uniaxial crystals. However, applying these materials usually requires a complicated cutting procedure to yield a crystal with a particular orientation. Here we demonstrate the first example of phase matching under the normal incidence of SHG in a biaxial monoclinic single crystal of zinc tungstate. The crystal was grown by the micro-pulling-down method with the (102) plane perpendicular to the growth direction. Additionally, at the same time white light was generated as a result of stimulated Raman scattering and multiphoton luminescence induced by higher-order effects such as three-photon luminescence enhanced by cascaded third-harmonic generation. The annealed crystal offers SHG intensities approximately four times larger than the as grown one; optimized growth and annealing conditions may lead to much higher SHG intensities. PMID:28338074

Self-Phase-Matched Second-Harmonic and White-Light Generation in a Biaxial Zinc Tungstate Single Crystal

NASA Astrophysics Data System (ADS)

Osewski, Pawel; Belardini, Alessandro; Petronijevic, Emilija; Centini, Marco; Leahu, Grigore; Diduszko, Ryszard; Pawlak, Dorota A.; Sibilia, Concita

2017-03-01

Second-order nonlinear optical materials are used to generate new frequencies by exploiting second-harmonic generation (SHG), a phenomenon where a nonlinear material generates light at double the optical frequency of the input beam. Maximum SHG is achieved when the pump and the generated waves are in phase, for example through birefringence in uniaxial crystals. However, applying these materials usually requires a complicated cutting procedure to yield a crystal with a particular orientation. Here we demonstrate the first example of phase matching under the normal incidence of SHG in a biaxial monoclinic single crystal of zinc tungstate. The crystal was grown by the micro-pulling-down method with the (102) plane perpendicular to the growth direction. Additionally, at the same time white light was generated as a result of stimulated Raman scattering and multiphoton luminescence induced by higher-order effects such as three-photon luminescence enhanced by cascaded third-harmonic generation. The annealed crystal offers SHG intensities approximately four times larger than the as grown one; optimized growth and annealing conditions may lead to much higher SHG intensities.

Macromolecule Crystal Quality Improvement in Microgravity: The Role of Impurities

NASA Technical Reports Server (NTRS)

Judge, Russell A.; Snell, Edward H.; Pusey, Marc L.; Sportiello, Michael G.; Todd, Paul; Bellamy, Henry; Borgstahl, Gloria E.; Pokros, Matt; Cassanto, John M.

2000-01-01

While macromolecule impurities may affect crystal size and morphology the over-riding question is; "How do macromolecule impurities effect crystal X-ray quality and diffraction resolution?" In the case of chicken egg white lysozyme, crystals can be grown in the presence of a number of impurities without affecting diffraction resolution. One impurity however, the lysozyme dimer, does negatively impact the X-ray crystal properties. Crystal quality improvement as a result of better partitioning of this impurity during crystallization in microgravity has been reported'. In our recent experimental work dimer partitioning was found to be not significantly different between the two environments. Mosaicity analysis of pure crystals showed a reduced mosaicity and increased signal to noise for the microgravity grown crystals. Dimer incorporation however, did greatly reduce the resolution limit in both ground and microgravity grown crystals. These results indicate that impurity effects in microgravity are complex and may rely on the conditions or techniques employed.

(PCG) Protein Crystal Growth Horse Serum Albumin

NASA Technical Reports Server (NTRS)

1995-01-01

Horse Serum Albumin crystals grown during the USML-1 (STS-50) mission's Protein Crystal Growth Glovebox Experiment. These crystals were grown using a vapor diffusion technique at 22 degrees C. The crystals were allowed to grow for nine days while in orbit. Crystals of 1.0 mm in length were produced. The most abundant blood serum protein, regulates blood pressure and transports ions, metabolites, and therapeutic drugs. Principal Investigator was Edward Meehan.

Experimental and density functional theory (DFT): A dual approach to probe the key properties of creatininium L-tartrate monohydrate single crystal for nonlinear optical applications

NASA Astrophysics Data System (ADS)

Thirumurugan, R.; Babu, B.; Anitha, K.; Chandrasekaran, J.

2017-12-01

A novel organic nonlinear optical (NLO) material, creatininium L-tartrate monohydrate (CTM) was synthesized and it was grown as single crystals with optical quality. 1H and 13C NMR spectral studies were performed and molecular structure of synthesized CTM compound was confirmed. Single crystal X-ray diffraction (SXRD) analysis confirmed that CTM was crystallized in orthorhombic system with non-centrosymmetric (NCS), P212121, space group. The grown crystal exhibited admirable properties such as second harmonic generation efficiency (SHG) (1.9 times KDP), and high laser damage threshold (LDT) value of 3.7 GW cm-2. CTM crystal displayed high transparency (∼60%) in the visible and near-IR region with low cut-off wavelength at 249 nm. Photoluminescence study confirmed blue wavelength emission (∼463 nm) of grown crystal. Thermal and mechanical behaviours have been successfully analysed for grown crystals. The dielectric studies were carried out for grown crystal as a function of frequencies at different temperatures. Hirshfeld surface and fingerprint plots provided the percentage of individual interactions contributed by each atom. Moreover, density functional theory (DFT) calculations have been employed to probe the frontier molecular orbitals (FMOs) and first hyperpolarizability (β) analysis of the optimized CTM structure. These results validated CTM as a suitable NLO candidate and were discussed in this work.

Purification, growth, and characterization of Zn(x)Cd(1-x)Se crystals

NASA Astrophysics Data System (ADS)

Silberman, E.; Burger, A.; Chen, W.; Henderson, D. O.; Morgan, S. H.; Springer, John M.; Yao, Y.

The purification of starting materials which were used in the growth of Zn(x)Cd(1-x)Se (x = 0.2) single crystals using the traveling solution method (TSM) is reported. Up to 13 cm long single crystals and as grown resistivities of 6 x 10(exp 12) ohm/cm could be achieved. Infrared and Raman spectra of Zn(0.2)Cd(0.8)Se are also presented and discussed.

Purification, growth, and characterization of Zn(x)Cd(1-x)Se crystals

NASA Technical Reports Server (NTRS)

Silberman, E.; Burger, A.; Chen, W.; Henderson, D. O.; Morgan, S. H.; Springer, John M.; Yao, Y.

1989-01-01

The purification of starting materials which were used in the growth of Zn(x)Cd(1-x)Se (x = 0.2) single crystals using the traveling solution method (TSM) is reported. Up to 13 cm long single crystals and as grown resistivities of 6 x 10(exp 12) ohm/cm could be achieved. Infrared and Raman spectra of Zn(0.2)Cd(0.8)Se are also presented and discussed.

Point Defect Distributions in ZnSe Crystals: Effects of Gravity Vector Orientation During Physical Vapor Transport Growth

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Feth, S.; Hirschfeld, D.; Smith, T. M.; Wang, Ling Jun; Volz, M. P.; Lehoczky, S. L.

1999-01-01

ZnSe crystals were grown by the physical vapor transport technique under horizontal and vertical (stabilized and destabilized) configurations. Secondary ion mass spectroscopy and photoluminescence measurements were performed on the grown ZnSe samples to map the distributions of [Si], [Fe], [Cu], [Al] and [Li or Na] impurities as well as Zn vacancy, [V (sub Zn)]. Annealings of ZnSe under controlled Zn pressures were studied to correlate the measured photoluminescence emission intensity to the equilibrium Zn partial pressure. In the horizontal grown crystals the segregations of [Si], [Fe], [Al] and [V (sub Zn)] were observed along the gravity vector direction whereas in the vertically stabilized grown crystal the segregation of these point defects was radially symmetrical. No apparent pattern was observed on the measured distributions in the vertically destabilized grown crystal. The observed segregations in the three growth configurations were interpreted based on the possible buoyancy-driven convection in the vapor phase.

Microgravity

NASA Image and Video Library

2000-05-01

The structure of the Satellite Tobacco Mosaic Viurus (STMV)--one of the smallest viruses known--has been successfully reduced using STMV crystals grown aboard the Space Shuttle in 1992 and 1994. The STMV crystals were up to 30 times the volume of any seen in the laboratory. At the time they gave the best resolution data ever obtained on any virus crystal. STMV is a small icosahedral plant virus, consisting of a protein shell made up of 60 identical protein subunits of molecular weight 17,500. Particularly noteworthy is the fact that, in contrast to the crystals grown on Earth, the crystals grown under microgravity conditions were visually perfect, with no striations or clumping of crystals. Furthermore, the x-ray diffraction data obtained from the space-grown crystals was of a much higher quality than the best data available at that time from ground-based crystals. This stylized ribbon model shows the protein coat in white and the nucleic acid in yellow. STMV is used because it is a simple protein to work with; studies are unrelated to tobacco. Credit: Dr. Alex McPherson, University of California at Irvin.

Microgravity

NASA Image and Video Library

2000-05-01

The structure of the Satellite Tobacco Mosaic Virus (STMV)--one of the smallest viruses known--has been successfully deduced using STMV crystals grown aboard the Space Shuttle in 1992 and 1994. The STMV crystals were up to 30 times the volume of any seen in the laboratory. At the same time they gave the best resolution data ever obtained on any virus crystal. STMV is a small icosahedral plant virus, consisting of a protein shell made up of 60 identical protein subunits of molecular weight 17,500. Particularly noteworthy is the fact that, in contrast to the crystal grown on Earth, the crystals grown under microgravity conditions were viusally perfect, with no striations or clumping of crystals. Furthermore, the X-ray diffraction data obtained from the space-grown crystals was of a much higher quality than the best data available at that time from ground-based crystals. This computer model shows the external coating or capsid. STMV is used because it is a simple protein to work with; studies are unrelated to tobacco. Credit: Dr. Alex McPherson, Univeristy of California at Irvin.

Melt growth of organic 4-(2-Phenylisopropyl) phenol single crystal and its structural, thermal, dielectric permittivity and optical properties

NASA Astrophysics Data System (ADS)

Sadhasivam, S.; Rajesh, N. P.

2017-12-01

A nonlinear optical (NLO) organic crystal 4-(2-Phenylisopropyl) phenol has been grown by a top seeded melt growth technique. The melt growth kinetics of solid-liquid (molten) interface and facets formation in melt growth were studied. The melt grown crystal has the (001), (00 1 bar),(110)(1 bar 1 bar 0) ,(1 bar 20),(1 2 bar 0),(2 bar 10) and(2 1 bar 0) different morphological face. The morphological characteristics of melt grown crystal helps to better infer the kinetic influence of melt and hone growth of organic material. The rhombohedral lattice cell parameters were measured by single crystal X-ray diffraction. 4-(2-Phenylisopropyl) phenol crystallizes in space group of R 3 bar . Thermal study shows that solid to liquid transition occurring at 350 K and decomposes at 597 K. The grown crystal was optically transparent in the wavelength range of 300-1100 nm. The low dielectric constant (9-11) was measured in the [001] of 4-(2-Phenylisopropyl) phenol crystal.

Satellite Tobacco Mosaic Virus (STMV)

NASA Technical Reports Server (NTRS)

2000-01-01

The structure of the Satellite Tobacco Mosaic Virus (STMV)--one of the smallest viruses known--has been successfully deduced using STMV crystals grown aboard the Space Shuttle in 1992 and 1994. The STMV crystals were up to 30 times the volume of any seen in the laboratory. At the same time they gave the best resolution data ever obtained on any virus crystal. STMV is a small icosahedral plant virus, consisting of a protein shell made up of 60 identical protein subunits of molecular weight 17,500. Particularly noteworthy is the fact that, in contrast to the crystal grown on Earth, the crystals grown under microgravity conditions were viusally perfect, with no striations or clumping of crystals. Furthermore, the X-ray diffraction data obtained from the space-grown crystals was of a much higher quality than the best data available at that time from ground-based crystals. This computer model shows the external coating or capsid. STMV is used because it is a simple protein to work with; studies are unrelated to tobacco. Credit: Dr. Alex McPherson, Univeristy of California at Irvin.

Satellite Tobacco Mosaic Virus Structure

NASA Technical Reports Server (NTRS)

2000-01-01

The structure of the Satellite Tobacco Mosaic Viurus (STMV)--one of the smallest viruses known--has been successfully reduced using STMV crystals grown aboard the Space Shuttle in 1992 and 1994. The STMV crystals were up to 30 times the volume of any seen in the laboratory. At the time they gave the best resolution data ever obtained on any virus crystal. STMV is a small icosahedral plant virus, consisting of a protein shell made up of 60 identical protein subunits of molecular weight 17,500. Particularly noteworthy is the fact that, in contrast to the crystals grown on Earth, the crystals grown under microgravity conditions were visually perfect, with no striations or clumping of crystals. Furthermore, the x-ray diffraction data obtained from the space-grown crystals was of a much higher quality than the best data available at that time from ground-based crystals. This stylized ribbon model shows the protein coat in white and the nucleic acid in yellow. STMV is used because it is a simple protein to work with; studies are unrelated to tobacco. Credit: Dr. Alex McPherson, University of California at Irvin.

Aspects of rf-heating and gas-phase doping of large scale silicon crystals grown by the Float Zone technique

NASA Astrophysics Data System (ADS)

Zobel, F.; Mosel, F.; Sørensen, J.; Dold, P.

2018-05-01

Float Zone growth of silicon crystals is known as the method for providing excellent material properties. Basic principle of this technique is the radiofrequency induction heating, main aspects of this method will be discussed in this article. In contrast to other methods, one of the advantages of the Float Zone technique is the possibility for in-situ doping via gas phase. Experimental results on this topic will be shown and discussed.

Synthesis, growth, spectral, electrical, mechanical and thermal characterization of a potential optical material: γ-glycine single crystal

NASA Astrophysics Data System (ADS)

Sivakumar, N.; Jayavel, R.; Anbalagan, G.; Yadav, R. R.

2018-06-01

Gamma glycine, an organic material was grown by slow solvent evaporation method. Conventional polythermal method was employed in the temperature range, 30-50 °C to obtain the solubility and the metastable zonewidth. The crystal and molecular structures were analyzed by X-ray powder diffraction, FT-IR and FT-Raman spectral studies. Optical refractive index was determined by prism coupling technique and was found to be 1.4488. Electrical properties such as ac conductivity and activation energy were studied for different temperatures in the frequency range from 40 Hz to 6 MHz. The dc electrical conductivity was estimated from the Cole-Cole plot and the values were found to be 2.19 × 10-6 Sm-1 at 353K and 1.46 × 10-6 Sm-1 at 373K respectively. Mechanical studies on the grown crystal revealed that the material belongs to soft materials category. Thermal conductivity and specific heat capacities were estimated by Hot Disk Thermal Constants Analyzer.

Low Temperature Flux Growth of 2H-SiC and Beta-Gallium Oxide

NASA Technical Reports Server (NTRS)

Singh, N. B.; Choa, Fow-Sen; Su, Ching-Hua; Arnold, Bradley; Kelly, Lisa

2016-01-01

We present brief overview of our study on the low temperature flux growth of two very important novel wide bandgap materials 2H-SiC and Beta-gallium oxide (Beta-Ga2O3). We have synthesized and grown 5 millimeter to 1 centimeter size single crystals of Beta-gallium oxide (Beta-Ga2O3). We used a flux and semi wet method to grow transparent good quality crystals. In the semi-wet method Ga2O3 was synthesized with starting gallium nitrate solution and urea as a nucleation agent. In the flux method we used tin and other metallic flux. This crystal was placed in an alumina crucible and temperature was raised above 1050 degrees Centigrade. After a time period of thirty hours, we observed prismatic and needle shaped crystals of gallium oxide. Scanning electron microscopic studies showed step growth morphology. Crystal was polished to measure the properties. Bandgap was measured 4.7electronvolts using the optical absorption curve. Another wide bandgap hexagonal 2H-SiC was grown by using Si-Al eutectic flux in the graphite crucible. We used slight AlN also as the impurity in the flux. The temperature was raised up to 1050 degrees Centigrade and slowly cooled to 850 degrees Centigrade. Preliminary characterization results of this material are also reported.

Crystallization of uric acid

NASA Astrophysics Data System (ADS)

Kalkura, S. Narayana; Vaidyan, V. K.; Kanakavel, M.; Ramasamy, P.

1993-09-01

Crystals of uric acid have been grown in tetra methoxy silane and silica gel medium. Small winged, transparent, platy crystals of uric acid of about 0.5x0.5x0.1 mm were grown and were found to be hydrated uric acid.

C-Axis-Oriented Hydroxyapatite Film Grown Using ZnO Buffer Layer

NASA Astrophysics Data System (ADS)

Sakoishi, Yasuhiro; Iguchi, Ryo; Nishikawa, Hiroaki; Hontsu, Shigeki; Hayami, Takashi; Kusunoki, Masanobu

2013-11-01

A method of fabricating c-axis-oriented hydroxyapatite film on a quartz crystal microbalance (QCM) sensor was investigated. ZnO was used as a template to obtain a hexagonal hydroxyapatite crystal of uniaxial orientation. The ZnO was grown as a c-axis film on a Au/quartz with the surface structure of a QCM sensor. Under optimized conditions, hydroxyapatite was deposited by pulsed laser deposition. X-ray diffraction showed the hydroxyapatite film to be oriented along the c-axis. Because Au and ZnO are applied to many devices, the anisotropic properties of hydroxyapatite may be incorporated into these devices as well as QCM sensors.

Luminescence properties of ZnxMg1-xSe layers

NASA Astrophysics Data System (ADS)

Bala, Waclaw; Firszt, Franciszek; Dzik, Janusz; Gapinski, Adam; Glowacki, Grzegorz

1995-10-01

This work deals with the study of luminescence properties of ZnxMg1-xSe layers prepared by different methods. ZnxMg1-xSe mixed crystal layers were obtained by: (a) thermal diffusion of Mg metal in the temperature range 1050 K - 1200 K into ZnSe single crystal grown by Bridgman method, and (b) epitaxial growth on (001) GaAs and (111) ZnTe substrates by MBE using elemental Zn, Se and Mg sources. The luminescence spectra of ZnxMg1-xSe layers grown on (001) GaAs and (111) ZnTe substrates are dominated by narrow blue and violet emission bands with maxima positioned at about 3.05 - 3.28 eV, 2.88 - 3.04 eV, and 2.81 - 2.705 eV.

Erbium Distribution in Single Crystal YAG Fibers Grown by Laser-Heated Pedestal Growth Technique

DTIC Science & Technology

2015-08-28

single crystal YAG fibers grown by laser - heated pedestal growth technique Single crystal (SC) yttrium aluminum garnet (YAG, Y3Al5O12) as a host...inserted into a SC YAG tube. This rod-in-tube was used as a preform in our laser -heated pedestal growth (LHPG) apparatus to grow a fiber with a radial...fibers grown by laser -heated pedestal growth technique Report Title Single crystal (SC) yttrium aluminum garnet (YAG, Y3Al5O12) as a host material has

Effect of L-Valine on the growth and characterization of Sodium Acid Phthalate (SAP) single crystals.

PubMed

Nirmala, L Ruby; Thomas Joseph Prakash, J

2013-06-01

Undoped and amino acid doped good quality single crystals of Sodium Acid Phthalate crystals (SAP) were grown by slow evaporation solution growth technique which are semiorganic in nature. The effect of amino acid (L-Valine) dopant on the growth and the properties of SAP single crystal was investigated. The single crystal X-ray diffraction studies and FT-IR studies were carried out to identify the crystal structure and the presence of functional groups in undoped and L-Valine doped SAP crystals. The transparent nature of the grown crystal was observed using UV-Visible spectrum. The thermal decomposition of the doped SAP crystals was investigated by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). The enhancement in the NLO property of the undoped and L-Valine doped SAP crystals using KDP crystal as a reference was studied using SHG measurements. Vickers micro hardness measurements are used for the study of mechanical strength of the grown crystals. Copyright © 2013 Elsevier B.V. All rights reserved.

Properties of high quality GaP single crystals grown by computer controlled liquid encapsulated Czochralski technique

NASA Astrophysics Data System (ADS)

Kokubun, Y.; Washizuka, S.; Ushizawa, J.; Watanabe, M.; Fukuda, T.

1982-11-01

The properties of GaP single crystals grown by an automatically diameter controlled liquid encapsulated Czochralski technique using a computer have been studied. A dislocation density less than 5×104 cm-2 has been observed for crystal grown in a temperature gradient lower than 70 °C/cm near the solid-liquid interface. Crystals have about 10% higher electron mobility than that of commercially available coracle controlled crystals and have 0.2˜0.5 compensation ratios. Yellow light emitting diodes using computer controlled (100) substrates have shown extremely high external quantum efficiency of 0.3%.

Protein crystal growth aboard the U.S. Space Shuttle flights STS-31 and STS-32

NASA Technical Reports Server (NTRS)

Delucas, Lawrence J.; Smith, Craig D.; Carter, Daniel C.; Twigg, Pam; He, Xiao-Min; Snyder, Robert S.; Weber, Patricia C.; Schloss, J. V.; Einspahr, H. M.; Clancy, L. L.

1992-01-01

Results obtained from the Shuttle flight STS-32 flown in January 1990, and preliminary results from the most recent Shuttle flight, STS-31, flown in April 1990, are presented. Crystals grown in microgravity environment include Canavalin, isocitrate lyase, human serum albumin, and Anti-HPr Fab. It is concluded that about 20 percent of proteins flown exhibit better morphologies or better quality data than their earth-grown counterparts. About 40 percent do not yield crystals at all and the remaining 40 percent yield crystals that are either too small for X-ray analysis or produce data of poorer quality than the best earth-grown crystals.

Crucibleless crystal growth and Radioluminescence study of calcium tungstate single crystal fiber

NASA Astrophysics Data System (ADS)

Silva, M. S.; Jesus, L. M.; Barbosa, L. B.; Ardila, D. R.; Andreeta, J. P.; Silva, R. S.

2014-11-01

In this article, single phase and high optical quality scheelite calcium tungstate single crystal fibers were grown by using the crucibleless laser heated pedestal growth technique. The as-synthesized calcium tungstate powders used for shaping seed and feed rods were investigated by X-ray diffraction technique. As-grown crystals were studied by Raman spectroscopy and Radioluminescence measurements. The results indicate that in both two cases, calcined powder and single crystal fiber, only the expected scheelite CaWO4 phase was observed. It was verified large homogeneity in the crystal composition, without the presence of secondary phases. The Radioluminescence spectra of the as-grown single crystal fibers are in agreement with that present in Literature for bulk single crystals, presented a single emission band centered at 420 nm when irradiated with β-rays.

Structural and optical properties of WTe2 single crystals synthesized by DVT technique

NASA Astrophysics Data System (ADS)

Dixit, Vijay; Vyas, Chirag; Pathak, V. M.; Soalanki, G. K.; Patel, K. D.

2018-05-01

Layered transition metal di-chalcogenide (LTMDCs) crystals have attracted much attention due to their potential in optoelectronic device applications recently due to realization of their monolayer based structures. In the present investigation we report growth of WTe2 single crystals by direct vapor transport (DVT) technique. These crystals are then characterized by energy dispersive analysis of x-rays (EDAX) to study stoichiometric composition after growth. The structural properties are studied by x-ray diffraction (XRD) and selected area electron diffraction (SAED) is used to confirm orthorhombic structure of grown WTe2 crystal. Surface morphological properties of the crystals are also studied by scanning electron microscope (SEM). The optical properties of the grown crystals are studied by UV-Visible spectroscopy which gives direct band gap of 1.44 eV for grown WTe2 single crystals.

Nonlinear optical and microscopic analysis of Cu2+ doped zinc thiourea chloride (ZTC) monocrystal

NASA Astrophysics Data System (ADS)

Ramteke, S. P.; Anis, Mohd; Pandian, M. S.; Kalainathan, S.; Baig, M. I.; Ramasamy, P.; Muley, G. G.

2018-02-01

Organometallic crystals offer considerable nonlinear response therefore, present article focuses on bulk growth and investigation of Cu2+ ion doped zinc thiourea chloride (ZTC) crystal to explore its technological impetus for laser assisted nonlinear optical (NLO) device applications. The Cu2+ ion doped ZTC bulk single crystal of dimension 03 × 2.4 × 0.4 cm3 has been grown from pH controlled aqueous solution by employing slow solvent evaporation technique. The structural analysis has been performed by means of single crystal X-ray diffraction technique. The doping of Cu2+ ion in ZTC crystal matrix has been confirmed by means of energy dispersive spectroscopic (EDS) technique. The origin of nonlinear optical properties in Cu2+ ion doped ZTC crystal has been studied by employing the Kurtz-Perry test and Z-scan analysis. The remarkable enhancement in second harmonic generation (SHG) efficiency of Cu2+ ion doped ZTC crystal with reference to ZTC crystal has been determined. The He-Ne laser assisted Z-scan analysis has been performed to determine the third order nonlinear optical (TONLO) nature of grown crystal. The TONLO parameters such as susceptibility, absorption coefficient, refractive index and figure of merit of Cu-ZTC crystal have been evaluated using the Z-scan transmittance data. The laser damage threshold of grown crystal to high intensity of Nd:YAG laser is found to be 706.2 MW/cm2. The hardness number, work hardening index, yield strength and elastic stiffness coefficient of grown crystal has been investigated under microhardness study. The etching study has been carried out to determine the growth likelihood, nature of etch pits and surface quality of grown crystal.

Microgravity

NASA Image and Video Library

1995-09-17

Horse Serum Albumin crystals grown during the USML-1 (STS-50) mission's Protein Crystal Growth Glovebox Experiment. These crystals were grown using a vapor diffusion technique at 22 degrees C. The crystals were allowed to grow for nine days while in orbit. Crystals of 1.0 mm in length were produced. The most abundant blood serum protein, regulates blood pressure and transports ions, metabolites, and therapeutic drugs. Principal Investigator was Edward Meehan.

Structural, optical, thermal and mechanical properties of Urea tartaric acid single crystals.

PubMed

Vinothkumar, P; Rajeswari, K; Kumar, R Mohan; Bhaskaran, A

2015-06-15

Urea tartaric acid (UT) an organic nonlinear optical (NLO) material was synthesized from aqueous solution and the crystals were grown by the slow evaporation technique. The single crystal X-ray diffraction (XRD) analysis revealed that the UT crystal belongs to the orthorhombic system. The functional groups of UT have been identified by the Fourier transform infrared spectral studies. The optical transparent window in the visible and near the IR regions was investigated. The transmittance of UT has been used to calculate the refractive index (n) as a function of the wavelength. The nonlinear optical property of the grown crystal has been confirmed by the Kurtz powder second harmonic generation test. The birefringence of the crystal was determined using a tungsten halogen lamp source. The laser induced surface damage threshold for the grown crystal was measured using the Nd:YAG laser. The anisotropic in mechanical property of the grown crystals was studied using Vicker's microhardness tester at different planes. The etch pit density of UT crystals was investigated. The thermal behavior of UT was investigated using the TG-DTA and DSC studies. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of Co-60 gamma radiation on optical, dielectric and mechanical properties of strontium L-ascorbate hexahydrate NLO crystal

NASA Astrophysics Data System (ADS)

Dileep, M. S.; Suresh Kumar, H. M.

2018-04-01

A potentially useful nonlinear optical semi-organic single crystal of strontium L-ascorbate hexahydrate (SLAH) was grown by solution growth slow evaporation technique at room temperature. The grown crystal is semi transparent, yellowish in color with monoclinic crystal system having space group P21 and is stable up to 198 °C. Further, SLAH crystals were irradiated with gamma rays produced by 60Co with different doses of 10 KGy, 30 KGy and 50 KGy at room temperature and then studied the effect of gamma-rays on dielectric properties, optical absorption, microhardness and SHG efficiency. The absorption study reveals that the absorbance of the grown crystal is appeared to be low throughout the visible region with a lower cutoff wavelength of 277 nm and these parameters are not affected upon gamma irradiation. The luminescence intensity of the crystal is also not affected by the irradiation. There is noticeable changes were observed in dielectric properties and hardness of the materials for different doses of gamma irradiation. The second harmonic generation (SHG) efficiency of the grown crystal is 0.54 times that of the KDP crystal and is decreased moderately by increasing the dosage of gamma irradiation.

Effect of the purity of starting materials on the growth and properties of potassium dihydrogen phosphate single crystals – A comparative study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajesh, P., E-mail: rajeshp@ssn.edu.in; Charoen In, Urit; Manyum, Prapun

2014-11-15

Highlights: • Bulk size KDP crystal has been grown with higher growth rate. • Systematic study on the effect of starting materials has been done. • Crystalline perfection is maintained in the entire crystal. - Abstract: A systematic study on the effect of purity of starting materials on the growth and properties of potassium dihydrogen phosphate single crystals is crucial for the future study of the material for nonlinear optical applications. Potassium dihydrogen phosphate crystals were grown using high pure (99.999%) and ordinary (99.9%) starting raw materials using slow cooling method in identical conditions. Their optical transparency and crystalline perfectionmore » are studied by UV and high resolution X-ray diffraction analyses respectively. The results are checked with the help of etching analyses. The full width at half maximum is 8″ which is close to that expected from the plane wave theory of dynamical X-ray diffraction for an ideally perfect crystal. Results of those studies are correlated with each other. The quantitative results show that the raw material plays an important role in the growth of good quality crystals.« less

Thermal, dielectric studies on pure and amino acid ( L-glutamic acid, L-histidine, L-valine) doped KDP single crystals

NASA Astrophysics Data System (ADS)

Kumaresan, P.; Moorthy Babu, S.; Anbarasan, P. M.

2008-05-01

Amino acids ( L-glutamic acid, L-histidine, L-valine) doped potassium dihydrogen phospate crystals are grown by solution growth technique. Slow cooling as well as slow evaporation methods were employed to grow these crystals. The concentration of dopants in the mother solution was varied from 0.1 mol% to 10 mol%. The solubility data for all dopants concentration were determined. There is variation in pH value and hence, there is habit modification of the grown crystals were characterized with UV-VIS, FT-IR studies, SHG trace elements and dielectric studies reveal slight distortion of lattice parameter for the heavily doped KDP crystals. UV-Visible spectra confirm the improvement in the transparency of these crystals on doping metal ions. FT-IR spectra reveal strong absorption band between 1400 and 1600 cm -1 for metal ion doped crystals. TGA-DTA studies reveal good thermal stability. The dopants increase the hardness value of the material and it also depends on the concentration of the dopants. Amino acids doping improved the NLO properties. The detailed results on the spectral parameters, habit modifications and constant values will be presented.

Reduction of Defects in Germanium-Silicon

NASA Technical Reports Server (NTRS)

Szofran, Frank R.; Benz, K. W.; Cobb, Sharon D.; Croell, Anne; Dold, P.; Motafef, S.; Schweizer, M.; Volz, Martin P.; Walker, J. S.

2003-01-01

Crystals grown without being in contact with a container have superior quality to otherwise similar crystals grown in direct contact with a container, especially with respect to impurity incorporation, formation of dislocations, and residual stress in the crystals. In addition to float-zone processing, detached Bridgman growth, although not a completely crucible-free method, is a promising tool to improve crystal quality. It does not suffer from the size limitations of float zoning and the impact of thermocapillary convection on heat and mass transport is expected to be negligible. Detached growth has been observed frequently during g experiments. Considerable improvements in crystalline quality have been reported for these cases. However, neither a thorough understanding of the process nor a quantitative assessment of the quality of these improvements exists. This project will determine the means to reproducibly grow GeSi alloys in a detached mode and seeks to compare processing-induced defects in Bridgman, detached-Bridgman, and floating-zone growth configurations in GeSi crystals (Si less than or equal to 10 at%) up to 20mm in diameter. Specific objectives include: measurement of the relevant material parameters such as contact angle, growth angle, surface tension, and wetting behavior of the GeSi-melt on potential crucible materials; determination of the mechanism of detached growth including the role of convection; quantitative determination of the differences in defects and impurities for crystals grown using normal Bridgman, detached Bridgman, and floating zone (FZ) methods; investigation of the influence of a defined flow imposed by a rotating magnetic field on the characteristics of detached growth; control of time-dependent Marangoni convection in the case of FZ growth by the use of a rotating magnetic field to examine the influence on the curvature of the solid-liquid interface and the heat and mass transport; and growth of benchmark quality GeSi-single crystals.

Large area and structured epitaxial graphene produced by confinement controlled sublimation of silicon carbide

PubMed Central

de Heer, Walt A.; Berger, Claire; Ruan, Ming; Sprinkle, Mike; Li, Xuebin; Hu, Yike; Zhang, Baiqian; Hankinson, John; Conrad, Edward

2011-01-01

After the pioneering investigations into graphene-based electronics at Georgia Tech, great strides have been made developing epitaxial graphene on silicon carbide (EG) as a new electronic material. EG has not only demonstrated its potential for large scale applications, it also has become an important material for fundamental two-dimensional electron gas physics. It was long known that graphene mono and multilayers grow on SiC crystals at high temperatures in ultrahigh vacuum. At these temperatures, silicon sublimes from the surface and the carbon rich surface layer transforms to graphene. However the quality of the graphene produced in ultrahigh vacuum is poor due to the high sublimation rates at relatively low temperatures. The Georgia Tech team developed growth methods involving encapsulating the SiC crystals in graphite enclosures, thereby sequestering the evaporated silicon and bringing growth process closer to equilibrium. In this confinement controlled sublimation (CCS) process, very high-quality graphene is grown on both polar faces of the SiC crystals. Since 2003, over 50 publications used CCS grown graphene, where it is known as the “furnace grown” graphene. Graphene multilayers grown on the carbon-terminated face of SiC, using the CCS method, were shown to consist of decoupled high mobility graphene layers. The CCS method is now applied on structured silicon carbide surfaces to produce high mobility nano-patterned graphene structures thereby demonstrating that EG is a viable contender for next-generation electronics. Here we present for the first time the CCS method that outperforms other epitaxial graphene production methods. PMID:21960446

Stoichiometric Effects on the Photoelectric Properties of LiInSe 2 Crystals for Neutron Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Lijian; Xu, Yadong; Zheng, Hongjian

6LiInSe 2 is a promising semiconductor candidate for thermal neutron detection due to its large capture cross-section. However, the charge collection efficiency is still insufficient for high resolution for the grown-in defects induced by the stoichiometric deviation. In this work, we report photoelectric properties of stoichiometric LiInSe 2 crystal boules up to 70 mm in length and 20 mm in diameter grown by the vertical Bridgman method. Inductively coupled plasma measurements demonstrate that the ratio of Li, In, and Se of the as-grown crystal is very close to 1:1:2, which is optimized by low temperature synthesis processing. The obtained singlemore » crystals display high bulk resistivity in the range of 10 11–10 12 Ω·cm and a direct band gap of 2.01–2.83 eV with a changeable color from red to yellow. The electronic structure of LiInSe 2 was studied using first-principles density functional theory calculations, which predicts that the antisite defects of In Li and Li In are the dominant factor for the different crystal colors observed. The stoichiometric LiInSe 2 crystal gives an improved energy resolution, for a semiconductor detector when illuminated with a 241Am@5.48 MeV α source, of 23.3%. In conclusion, the electron mobility-lifetime product (μτ) is ~2.5 × 10 –5 cm 2 V –1.« less

On the Chemistry and Physical Properties of Flux and Floating Zone Grown SmB6 Single Crystals

PubMed Central

Phelan, W. A.; Koohpayeh, S. M.; Cottingham, P.; Tutmaher, J. A.; Leiner, J. C.; Lumsden, M. D.; Lavelle, C. M.; Wang, X. P.; Hoffmann, C.; Siegler, M. A.; Haldolaarachchige, N.; Young, D. P.; McQueen, T. M.

2016-01-01

Recent theoretical and experimental findings suggest the long-known but not well understood low temperature resistance plateau of SmB6 may originate from protected surface states arising from a topologically non-trivial bulk band structure having strong Kondo hybridization. Yet others have ascribed this feature to impurities, vacancies, and surface reconstructions. Given the typical methods used to prepare SmB6 single crystals, flux and floating-zone procedures, such ascriptions should not be taken lightly. We demonstrate how compositional variations and/or observable amounts of impurities in SmB6 crystals grown using both procedures affect the physical properties. From X-ray diffraction, neutron diffraction, and X-ray computed tomography experiments we observe that natural isotope containing (SmB6) and doubly isotope enriched (154Sm11B6) crystals prepared using aluminum flux contain co-crystallized, epitaxial aluminum. Further, a large, nearly stoichiometric crystal of SmB6 was successfully grown using the float-zone technique; upon continuing the zone melting, samarium vacancies were introduced. These samarium vacancies drastically alter the resistance and plateauing magnitude of the low temperature resistance compared to stoichiometric SmB6. These results highlight that impurities and compositional variations, even at low concentrations, must be considered when collecting/analyzing physical property data of SmB6. Finally, a more accurate samarium-154 coherent neutron scattering length, 8.9(1) fm, is reported. PMID:26892648

On the Chemistry and Physical Properties of Flux and Floating Zone Grown SmB 6 Single Crystals

DOE PAGES

Phelan, W. A.; Koohpayeh, S. M.; Cottingham, P.; ...

2016-02-19

Recent theoretical and experimental findings suggest the long-known but not well understood low temperature resistance plateau of SmB 6 may originate from protected surface states arising from a topologically non-trivial bulk band structure having strong Kondo hybridization. Yet others have ascribed this feature to impurities, vacancies, and surface reconstructions. Given the typical methods used to prepare SmB 6 single crystals, flux and floating-zone procedures, such ascriptions should not be taken lightly. We demonstrate how compositional variations and/or observable amounts of impurities in SmB 6 crystals grown using both procedures affect the physical properties. From X-ray diffraction, neutron diffraction, and X-raymore » computed tomography experiments we observe that natural isotope containing (SmB 6) and doubly isotope enriched ( 154Sm 11B 6) crystals prepared using aluminum flux contain co-crystallized, epitaxial aluminum. Further, a large, nearly stoichiometric crystal of SmB 6 was successfully grown using the float-zone technique; upon continuing the zone melting, samarium vacancies were introduced. These samarium vacancies drastically alter the resistance and plateauing magnitude of the low temperature resistance compared to stoichiometric SmB 6. Finally, these results highlight that impurities and compositional variations, even at low concentrations, must be considered when collecting/analyzing physical property data of SmB 6. Finally, a more accurate samarium-154 coherent neutron scattering length, 8.9(1) fm, is reported.« less

Stoichiometric Effects on the Photoelectric Properties of LiInSe 2 Crystals for Neutron Detection

DOE PAGES

Guo, Lijian; Xu, Yadong; Zheng, Hongjian; ...

2018-04-16

6LiInSe 2 is a promising semiconductor candidate for thermal neutron detection due to its large capture cross-section. However, the charge collection efficiency is still insufficient for high resolution for the grown-in defects induced by the stoichiometric deviation. In this work, we report photoelectric properties of stoichiometric LiInSe 2 crystal boules up to 70 mm in length and 20 mm in diameter grown by the vertical Bridgman method. Inductively coupled plasma measurements demonstrate that the ratio of Li, In, and Se of the as-grown crystal is very close to 1:1:2, which is optimized by low temperature synthesis processing. The obtained singlemore » crystals display high bulk resistivity in the range of 10 11–10 12 Ω·cm and a direct band gap of 2.01–2.83 eV with a changeable color from red to yellow. The electronic structure of LiInSe 2 was studied using first-principles density functional theory calculations, which predicts that the antisite defects of In Li and Li In are the dominant factor for the different crystal colors observed. The stoichiometric LiInSe 2 crystal gives an improved energy resolution, for a semiconductor detector when illuminated with a 241Am@5.48 MeV α source, of 23.3%. In conclusion, the electron mobility-lifetime product (μτ) is ~2.5 × 10 –5 cm 2 V –1.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aliev, Ziya S., E-mail: ziyasaliev@gmail.com; Institute of Physics, ANAS, H.Javid ave. 131, AZ1143 Baku; Donostia International Physics Center

Single crystals of the ternary copper compounds CuTlS and CuTlSe have been successfully grown from stoichiometric melt by using vertical Bridgman-Stockbarger method. The crystal structure of the both compounds has been determined by powder and single crystal X-Ray diffraction. They crystallize in the PbFCl structure type with two formula units in the tetragonal system, space group P4/nmm, a=3.922(2); c=8.123(6); Z=2 and a=4.087(6); c=8.195(19) Å; Z=2, respectively. The band structure of the reported compounds has been analyzed by means of full-potential linearized augmented plane-wave (FLAPW) method based on the density functional theory (DFT). Both compounds have similar band structures and aremore » narrow-gap semiconductors with indirect band gap. The resistivity measurements agree with a semiconductor behavior although anomalies are observed at low temperature. - Graphical abstract: The crystal structures of CuTl and CuTlSe are isostructural with the PbFCl-type and the superconductor LiFeAs-type tetragonal structure. The band structure calculations confirmed that they are narrow-gap semiconductors with indirect band gaps of 0.326 and 0.083 eV. The resistivity measurements, although confirming the semiconducting behavior of both compounds exhibit unusual anomalies at low temperatures. - Highlights: • Single crystals of CuTlS and CuTlSe have been successfully grown by Bridgman-Stockbarger method. • The crystal structure of the both compounds has been determined by single crystal XRD. • The band structure of the both compounds has been analyzed based on the density functional theory (DFT). • The resistivity measurements have been carried out from room temperature down to 10 K.« less

Growth, structural, physical and computational perspectives of trans-4-hydroxy-l-proline: a promising organic nonlinear optical material with large laser-induced damage threshold

NASA Astrophysics Data System (ADS)

Thirumurugan, Ramaiah; Anitha, Kandasamy

2017-05-01

In this work, a systematic study of an organic nonlinear optical (NLO) material, trans-4-hydroxy-l-proline (THP), C5H9NO3 is reported. An optical quality single crystals of THP have been successfully grown by using slow evaporation solution growth technique (SEST). The single crystal x-ray diffraction (SXRD) analysis reveals that grown crystal belongs to the orthorhombic system with non-centrosymmetric space group (NCS), P212121. Powder x-ray diffraction (PXRD) analysis shows relatively a good crystalline nature. The molecular structure of THP was recognized by NMR (1H and 13C) studies and its vibrational modes were confirmed by FTIR and FT-Raman vibrational studies. UV-Vis-NIR spectrum of grown crystal shows high optical transparency in the visible and near-IR region with low near-UV cut-off wavelength at 218 nm. Photoluminescence study confirms ultraviolet wavelength emission of THP crystal. The second harmonic generation (SHG) efficiency of grown crystal is 1.6 times greater with respect to standard potassium dihydrogen phosphate (KDP). Nonlinear refractive index (n 2) and nonlinear absorption coefficient (β) were determined using the Z-scan technique. The title compound owns high thermal stability of 294 °C and specific heat capacity (C P) of 1.21 J g-1 K-1 at 300 K and 11.33 J g-1 K-1 at 539 K (melting point). The laser-induced damage threshold (LDT) value of grown crystal was measured as 7.25 GW cm-2. The crystal growth mechanism and defects of grown crystal were studied by chemical etching technique. Mechanical strength was extensively studied by Vickers microhardness test and crystal void percentage analysis. Moreover, density functional theory (DFT) studies were carried out to probe the Mulliken charge distribution, frontier molecular orbitals (FMOs) and first order hyperpolarizability (β) of the optimized molecular structure to get a better insight of the molecular properties. These characterization results endorse that grown THP crystal as a suitable candidate for NLO applications with large LDT.

Study of single crystals of metal solid solutions

NASA Technical Reports Server (NTRS)

Doty, J. P.; Reising, J. A.

1973-01-01

The growth of single crystals of relatively high melting point metals such as silver, copper, gold, and their alloys was investigated. The purpose was to develop background information necessary to support a space flight experiment and to generate ground based data for comparison. The ground based data, when compared to the data from space grown crystals, are intended to identify any effects which zero-gravity might have on the basic process of single crystal growth of these metals. The ultimate purposes of the complete investigation are to: (1) determine specific metals and alloys to be investigated; (2) grow single metal crystals in a terrestrial laboratory; (3) determine crystal characteristics, properties, and growth parameters that will be effected by zero-gravity; (4) evaluate terrestrially grown crystals; (5) grow single metal crystals in a space laboratory such as Skylab; (6) evaluate the space grown crystals; (7) compare for zero-gravity effects of crystal characteristics, properties, and parameters; and (8) make a recommendation as to production of these crystals as a routine space manufacturing proceses.

A Test of Macromolecular Crystallization in Microgravity: Large, Well-Ordered Insulin Crystals

NASA Technical Reports Server (NTRS)

Borgstahl, Gloria E. O.; Vahedi-Faridi, Ardeschir; Lovelace, Jeff; Bellamy, Henry D.; Snell, Edward H.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

Crystals of insulin grown in microgravity on space shuttle mission STS-95 were extremely well-ordered and unusually large (many > 2 mm). The physical characteristics of six microgravity and six earth-grown crystals were examined by X-ray analysis employing superfine f slicing and unfocused synchrotron radiation. This experimental setup allowed hundreds of reflections to be precisely examined for each crystal in a short period of time. The microgravity crystals were on average 34 times larger, had 7 times lower mosaicity, had 54 times higher reflection peak heights and diffracted to significantly higher resolution than their earth grown counterparts. A single mosaic domain model could account for reflections in microgravity crystals whereas reflections from earth crystals required a model with multiple mosaic domains. This statistically significant and unbiased characterization indicates that the microgravity environment was useful for the improvement of crystal growth and resultant diffraction quality in insulin crystals and may be similarly useful for macromolecular crystals in general.

Growth and properties of benzil doped benzimidazole (BMZ) single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babu, R. Ramesh, E-mail: rampap2k@yahoo.co.in; Crystal Growth and Crystallography Section, National Physical Laboratory, Krishnan Marg, New Delhi 110 012; Sukumar, M.

2010-09-15

In the present work, we have made an attempt to study the effect of benzil doping on the properties of benzimidazole single crystals. For this purpose we have grown pure and benzil doped benzimidazole single crystals by vertical Bridgman technique. The grown crystals were characterized by various characterization techniques. The presence of dopants confirmed by powder X-ray diffraction (XRD). Crystalline perfection of the grown crystals has been analysed by high-resolution X-ray diffraction (HRXRD). The transmittance, electrical property and mechanical strength have been analysed using UV-vis-NIR spectroscopic, dielectric and Vicker's hardness studies. The relative second harmonic generation efficiency of pure andmore » doped benzimidazole crystals measured using Kurtz powder test.« less

A photoluminescence, thermoluminescence and electron paramagnetic resonance study of EFG grown europium doped lithium fluoride (LiF) crystals

NASA Astrophysics Data System (ADS)

Seth, Pooja; Swati, G.; Haranath, D.; Rao, S. M. D.; Aggarwal, Shruti

2018-07-01

Europium (Eu) doped LiF crystals have been grown by the Edge-defined film fed growth (EFG) technique. The designing and installation of the furnace used for the growth of the crystals have been discussed in detail. In the present study, Eu (Eu2O3) has been doped in LiF in different concentration (0.02-0.2 wt %). X-ray diffractometry (XRD) and Energy Dispersive X-ray (EDX) spectroscopy confirms the incorporation of Eu in LiF. The influence of Eu on LiF has been investigated through photoluminescence (PL), thermoluminescence (TL) and electron paramagnetic resonance (EPR) in as-grown and annealed crystals. PL emission spectra shows the presence of both Eu3+ and Eu2+ form in the as-grown crystals which is confirmed by EPR results. Whereas, in annealed crystals, Eu is present predominantly as Eu2+ form. This suggests that growing crystals at high temperature (∼900 °C) in argon gas atmosphere through EFG technique favours the reduction of Eu3+ → Eu2+. This reduction phenomenon has been explained on the basis of charge compensation model. TL study of the LiF: Eu (0.02-0.2 wt %) crystals has been done after irradiation with Co60 gamma rays. In this study, it has been observed that the TL intensity as well as glow curve structure of LiF: Eu crystals are a strong function of Eu concentration. The maximum TL is observed at Eu concentration of 0.05 wt% at which a well defined glow curve structure with a prominent peak at 185 °C and a small peak at 253 °C. Beyond this concentration (0.05 wt %), TL intensity decreases due to aggregation of defects in the host. The peak at 185 °C in LiF: Eu (0.05 wt %) is certainly due to the presence of Eu2+ associated defects which is also supported by the PL spectra. It has been observed that Eu doping have a key role in creation of more defect levels which lead to the increased number of electron and hole traps. Further, trapping parameters are analysed using glow curve deconvolution method to have an insight study of TL phenomena. Further, TL glow curve structure of as-grown and annealed crystal are distinct which may be attributed to the nature of defect traps formed inside the LiF.

Optimization of the photorefractivity in II-IV semiconductors. Final report, March 1996--March 1997

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jagannathan, G.V.; Trivedi, S.B.; Kutcher, S.W.

1998-11-01

This work was aimed at optimization of the photorefractivity in the II-VI semiconductors CdTe, ZnTe and Cd{sub x{minus}1}Zn{sub (x)}Te for real-time optical signal processing applications at near infrared wavelengths. During this work, several crystals of ZnTe, CdTe and Cd{sub x{minus}1}Zn{sub (x)}Te were grown. Crystal growth of ZnTe and CdTe was carried out using low supersaturation nucleation and `contactless` growth by Vertical Physical Vapor Transport (PVT) in closed ampoules and the CdTe and Cd{sub x{minus}1}Zn{sub (x)}Te crystals were grown using the vertical Bridgman technique. The quality of the crystals grown during this work was evaluated based on optical, electrical and structuralmore » characterization. Infrared microscopy was used to examine the internal crystalline structure of the samples. Most of the crystals grown during this work exhibited photorefractivity and photoconductivity. The resistivity of the vanadium doped crystals under dark conditions was found to be between 10 {sup 8} to 10 {sup 10} ohms cm. The resistivity decreased significantly in the presence of illumination indicating that the crystals were highly photoconductive. The photorefractive properties of the crystals grown during this project were characterized by two beam coupling. All of the measurements revealed a strong photorefractive nonlinear effect.« less

The optical properties of CdS crystal grown by the sublimation method

NASA Astrophysics Data System (ADS)

Hong, K. J.; Jeong, T. S.; Yoon, C. J.; Shin, Y. J.

2000-09-01

A cadmium sulfide (CdS) single crystal was grown by the sublimation method without a seed crystal in a two-stage vertical electric furnace. The carrier concentration and mobility obtained from Hall measurements at room temperature were 2.90 ×10 16 cm-3 and 316 cm 2/V s, respectively. The photoluminescence and the photocurrent measurement of the CdS single crystal have been performed in the temperature ranging from 20 to 293 K. From the photoluminescence measurement, the energy of the free exciton Ex(A) and Ex(B) has been obtained to be 2.5511 and 2.5707 eV, respectively. The variance of the peak position, intensity, and linewidth of the free excitons as a function of the temperature have been investigated by means of the conventional empirical relations and Toyozawa's theory. The crystal field of the CdS and its splitting energy, Δ cr, have been found to be 19.6 meV. In the photocurrent measurement, only the Ex(A) exciton peak has been observed. The energy band gap of the CdS at room temperature was determined to be 2.4749 eV by the photoluminescence and photocurrent measurement. Also, the temperature dependence of the energy band gap of the CdS, Eg( T), has been examined.

Single crystal growth of submillimeter diameter sapphire tube by the micro-pulling down method

NASA Astrophysics Data System (ADS)

Kamada, Kei; Murakami, Rikito; Kochurikhin, Vladimir V.; Luidmila, Gushchina; Jin Kim, Kyoung; Shoji, Yasuhiro; Yamaji, Akihiro; Kurosawa, Shunsuke; Ohashi, Yuji; Yokota, Yuui; Yoshikawa, Akira

2018-06-01

This paper addresses several aspects of the μ-PD growth technology as applied to submillimeter diameter sapphire tubes for UFD application. The μ-PD method has been successfully adapted for single crystal sapphire tube growth. A compound crucible made possible the growth of single crystal sapphire tube as small as around 0.70-0.72 mm in outer diameter and 0.28-0.29 in inner diameter over 160 mm in length at growth rate of 2-4 mm/min along 〈0 0 1〉 direction. An Ir crucible with a die composed of an equivalent hole and Ir wire was heated by RF coil in N2 atmosphere. The μ-PD method has been successfully adapted for single crystal sapphire tube growth. Grown crystal tube showed good XRC value of 30.2 arcsec.

Multicolor photonic crystal laser array

DOEpatents

Wright, Jeremy B; Brener, Igal; Subramania, Ganapathi S; Wang, George T; Li, Qiming

2015-04-28

A multicolor photonic crystal laser array comprises pixels of monolithically grown gain sections each with a different emission center wavelength. As an example, two-dimensional surface-emitting photonic crystal lasers comprising broad gain-bandwidth III-nitride multiple quantum well axial heterostructures were fabricated using a novel top-down nanowire fabrication method. Single-mode lasing was obtained in the blue-violet spectral region with 60 nm of tuning (or 16% of the nominal center wavelength) that was determined purely by the photonic crystal geometry. This approach can be extended to cover the entire visible spectrum.

TRANSVERSE MODE ELECTRO-OPTIC MATERIALS.

DTIC Science & Technology

electro - optic modulators presently used are crystals such as KDP which exhibit a longitudinal electro - optic effect. It has been demonstrated that a more efficient modulator can be produced when a crystal having a transverse electro - optic effect is employed. Generally these crystals are produced either from the melt or from fluxes. Since melt grown crystals must be cooled through several hundred degrees and often must undergo phase transitions, these crystals are generally highly strained. Flux grown crystals are also

The development and application of new crystallization method for tobacco mosaic virus coat protein.

PubMed

Li, Xiangyang; Song, Baoan; Hu, Deyu; Wang, Zhenchao; Zeng, Mengjiao; Yu, Dandan; Chen, Zhuo; Jin, Linhong; Yang, Song

2012-11-21

Although tobacco mosaic virus (TMV) coat protein (CP) has been isolated from virus particles and its crystals have grown in ammonium sulfate buffers for many years, to date, no one has reported on the crystallization of recombinant TMV-CP connecting peptides expressed in E. coli. In the present papers genetically engineered TMV-CP was expressed, into which hexahistidine (His) tags or glutathione-S-transferase (GST) tags were incorporated. Considering that GST-tags are long peptides and His-tags are short peptides, an attempt was made to grow crystals of TMV-CP cleaved GST-tags (WT-TMV-CP32) and TMV-CP incorporated His-tags (WT-His-TMV-CP12) simultaneously in ammonium sulfate buffers and commercial crystallization reagents. It was found that the 20S disk form of WT-TMV-CP32 and WT-His-TMV-CP12 did not form high resolution crystals by using various crystallization buffers and commercial crystallization reagents. Subsequently, a new experimental method was adopted in which a range of truncated TMV-CP was constructed by removing several amino acids from the N- or the C-terminal, and high resolution crystals were grown in ammonium sulfate buffers and commercial crystallization reagents. The new crystallization method was developed and 3.0 Å resolution macromolecular crystal was thereby obtained by removing four amino acids at the C-terminal of His-TMV-CP and connecting six His-tags at the N-terminal of His-TMV-CP (TR-His-TMV-CP19). The Four-layer aggregate disk structure of TR-His-TMV-CP19 was solved. This phenomenon showed that peptides at the C-terminus hindered the growth of high resolution crystals and the peptides interactions at the N-terminus were attributed to the quality of TMV-CP crystals. A 3.0 Å resolution macromolecular crystal of TR-His-TMV-CP19 was obtained and the corresponding structure was solved by removing four amino acids at the C-terminus of TMV-CP and connecting His-tags at the N-terminus of TMV-CP. It indicated that short peptides influenced the resolution of TMV-CP crystals.

Growth, spectral, thermal, laser damage threshold, microhardness, dielectric, linear and nonlinear optical properties of an organic single crystal: L-phenylalanine DL-mandelic acid

NASA Astrophysics Data System (ADS)

Jayaprakash, P.; Peer Mohamed, M.; Krishnan, P.; Nageshwari, M.; Mani, G.; Lydia Caroline, M.

2016-12-01

Single crystals of L-phenylalanine dl-mandelic acid [C9H11NO2. C8H8O3], have been grown by the slow evaporation technique at room temperature using aqueous solution. The single crystal XRD study confirms monoclinic system for the grown crystal. The functional groups present in the grown crystal have been identified by FTIR and FT-Raman analyses. The optical absorption studies show that the crystal is transparent in the visible region with a lower cut-off wavelength of 257 nm and the optical band gap energy Eg is determined to be 4.62 eV. The Kurtz powder second harmonic generation was confirmed using Nd:YAG laser with fundamental wavelength of 1064 nm. Further, the thermal studies confirmed no weight loss up to 150°C for the as-grown crystal. The photoluminescence spectrum exhibited three peaks (414 nm, 519 nm, 568 nm) due to the donation of protons from carboxylic acid to amino group. Laser damage threshold value was found to be 4.98 GW/cm2. The Vickers microhardness test was carried out on the grown crystals and there by Vickers hardness number (Hv), work hardening coefficient (n), yield strength (σy), stiffness constant C11 were evaluated. The dielectric behavior of the crystal has been determined in the frequency range 50 Hz-5 MHz at various temperatures.

Bridgman Growth of Germanium Crystals in a Rotating Magnetic Field

NASA Technical Reports Server (NTRS)

Volz, M. P.; Walker, J. S.; Schweizer, M.; Cobb, S. D.; Szofran, F. R.

2004-01-01

A series of (100)-oriented gallium-doped germanium crystals have been grown by the Bridgman method and under the influence of a rotating magnetic field (RMF). Time-dependent flow instabilities occur when the critical magnetic Taylor number (Tm(sup c) is exceeded, and this can be observed by noting the appearance of striations in the grown crystals. The experimental data indicate that Tm(sup c) increases as the aspect ratio of the melt decreases. Modeling calculations predicting Tm(sup c) as a function of aspect ratio are in reasonable agreement with the experimental data. The RMF has a marked affect on the interface shape, changing it from concave to nearly flat as the RMF strength is increased. Also, by pulsing the RMF on and off, it is shown that intentional interface demarcations can be introduced.

Microgravity

NASA Image and Video Library

1994-02-01

The comparison of protein crystal, Recombiant Human Insulin; space-grown (left) and earth-grown (right). On STS-60, Spacehab II indicated that space-grown crystals are larger and of greater optical clarity than their earth-grown counterparts. Recombiant Human Insulin facilitates the incorporation of glucose into cells. In diabetics, there is either a decrease in or complete lack of insulin, thereby leading to several harmful complications. Principal Investigator is Larry DeLucas.

Synthesis, growth, structural modeling and physio-chemical properties of a charge transfer molecule: Guanidinium tosylate

NASA Astrophysics Data System (ADS)

Era, Paavai; Jauhar, RO. MU.; Vinitha, G.; Murugakoothan, P.

2018-05-01

An organic nonlinear optical material, guanidinium tosylate was synthesized adopting slow evaporation method and the crystals were harvested from aqueous methanolic medium with dimensions 13 × 9 × 3 mm3. Constitution of crystalline material was confirmed by single crystal X-ray diffraction study. The title compound crystallizes in the monoclinic crystal system with space group P21/c. The UV-vis-NIR spectral study of the grown crystal exhibits high transparency of 80% in the entire visible region with lower cut-off wavelength at 282 nm. Optimized molecular geometry of the grown crystal was obtained using density functional theory (DFT) and the frontier energy gaps calculated from the DFT aids to understand the charge transfer taking place in the molecule. The dielectric properties were studied as a function of temperature and frequency to find the charge distribution within the crystal. The titular compound is thermally stable up to 230 °C assessed by thermogravimetric and differential thermal analysis. Anisotropy in the mechanical behavior was observed while measuring for individual planes. The laser induced surface damage threshold of the grown crystal was measured to be 0.344 GW/cm2 for 1064 nm Nd:YAG laser radiation. Z-scan technique confirms the third-order nonlinear optical property with the ascertained nonlinear refractive index (n2), nonlinear absorption coefficient (β) and third order nonlinear susceptibility (χ(3)). Optical limiting study divulges that the transmitted output power step-up linearly with the increase of the input power at lower power realms and saturates from the threshold 24.95 mW/cm2 and amplitude 0.23 mW/cm2.

Growth of InxGa1−xSb alloy semiconductor at the International Space Station (ISS) and comparison with terrestrial experiments

PubMed Central

Inatomi, Y; Sakata, K; Arivanandhan, M; Rajesh, G; Nirmal Kumar, V; Koyama, T; Momose, Y; Ozawa, T; Okano, Y; Hayakawa, Y

2015-01-01

Background: InxGa1−xSb is an important material that has tunable properties in the infrared (IR) region and is suitable for IR-device applications. Since the quality of crystals relies on growth conditions, the growth process of alloy semiconductors can be examined better under microgravity (μG) conditions where convection is suppressed. Aims: To investigate the dissolution and growth process of InxGa1−xSb alloy semiconductors via a sandwiched structure of GaSb(seed)/InSb/GaSb(feed) under normal and μG conditions. Methods: InxGa1−xSb crystals were grown at the International Space Station (ISS) under μG conditions, and a similar experiment was conducted under terrestrial conditions (1G) using the vertical gradient freezing (VGF) method. The grown crystals were cut along the growth direction and its growth properties were studied. The indium composition and growth rate of grown crystals were calculated. Results: The shape of the growth interface was nearly flat under μG, whereas under 1G, it was highly concave with the initial seed interface being nearly flat and having facets at the peripheries. The quality of the μG crystals was better than that of the 1G samples, as the etch pit density was low in the μG sample. The growth rate was higher under μG compared with 1G. Moreover, the growth started at the peripheries under 1G, whereas it started throughout the seed interface under μG. Conclusions: Kinetics played a dominant role under 1G. The suppressed convection under μG affected the dissolution and growth process of the InxGa1−xSb alloy semiconductor. PMID:28725715

Single crystal structure and SHG of defect pyrochlores CsB{sup V}MoO{sub 6} (B{sup V}=Nb,Ta)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fukina, D.G., E-mail: dianafuk@yandex.ru; Suleimanov, E.V.; Yavetskiy, R.P.

2016-09-15

The crystal structure and non-linear optical properties of CsNbMoO{sub 6} and CsTaMoO{sub 6} defect pyrochlores have been studied. The single crystals of these compounds grown by the flux method possess an octahedral faceting and reach up to 50 µm in size. The crystal structures of CsB{sup V}MoO{sub 6} (B{sup V}=Nb, Ta) were investigated by X-ray diffraction method. Both compounds crystallize in the cubic symmetry with noncentrosymmetric space group F-43m. The second harmonic generation of CsNbMoO{sub 6} and CsTaMoO{sub 6}was found to be 1.6×10{sup −2} and 8.5×10{sup −4} of lithium niobate, correspondingly. It has been determined that distortions of [MO{sub 6}]more » polyhedra (M=Nb, Ta, Mo) as well as polarizability and covalency of Nb–O and Ta–O bonds have a great effect on the second harmonic generation. - Highlights: • CsNbMoO{sub 6} and CsTaMoO{sub 6} homogeneous single crystals have been grown. • The crystal structure of CsTaMoO{sub 6} has been studied. • Nonlinear optical properties of CsNbMoO{sub 6} and CsTaMoO{sub 6} have been found. • The microscopic origin of the second harmonic generation (SHG) response have been identified.« less

Bulk Crystal Growth of Piezoelectric PMN-PT Crystals Using Gradient Freeze Technique for Improved SHM Sensors

NASA Technical Reports Server (NTRS)

Aggarwal, Mohan D.; Kochary, F.; Penn, Benjamin G.; Miller, Jim

2007-01-01

There has been a growing interest in recent years in lead based perovskite ferroelectric and relaxor ferroelectric solid solutions because of their excellent dielectric, piezoelectric and electrostrictive properties that make them very attractive for various sensing, actuating and structural health monitoring (SHM) applications. We are interested in the development of highly sensitive and efficient PMN-PT sensors based on large single crystals for the structural health monitoring of composite materials that may be used in future spacecrafts. Highly sensitive sensors are needed for detection of defects in these materials because they often tend to fail by distributed and interacting damage modes and much of the damage occurs beneath the top surface of the laminate and not detectable by visual inspection. Research is being carried out for various combinations of solid solutions for PMN-PT piezoelectric materials and bigger size crystals are being sought for improved sensor applications. Single crystals of this material are of interest for sensor applications because of their high piezoelectric coefficient (d33 greater than 1700 pC/N) and electromechanical coefficients (k33 greater than 0.90). For comparison, the commonly used piezoelectric ceramic lead zirconate titanate (PZT) has a d33 of about 600 pC/N and electromechanical coefficients k33 of about 0.75. At the present time, these piezoelectric relaxor crystals are grown by high temperature flux growth method and the size of these crystals are rather small (3x4x5 mm(exp 3). In the present paper, we have attempted to grow bulk single crystals of PMN-PT in a 2 inch diameter platinum crucible and successfully grown a large size crystal of 67%PMN-33%PT using the vertical gradient freeze technique with no flux. Piezoelectric properties of the grown crystals are investigated. PMN-PT plates show excellent piezoelectric properties. Samples were poled under an applied electric field of 5 kV/cm. Dielectric properties at a frequency of 1 kHz are examined. The grown PMN-PT crystals show typical relaxor dielectric properties. Additionally, the thermal properties of the sample are tested. The results are in good agreement with those found in the literature and some are reported for the first time.

Preferred orientations of laterally grown silicon films over amorphous substrates using the vapor-liquid-solid technique

NASA Astrophysics Data System (ADS)

LeBoeuf, J. L.; Brodusch, N.; Gauvin, R.; Quitoriano, N. J.

2014-12-01

A novel method has been optimized so that adhesion layers are no longer needed to reliably deposit patterned gold structures on amorphous substrates. Using this technique allows for the fabrication of amorphous oxide templates known as micro-crucibles, which confine a vapor-liquid-solid (VLS) catalyst of nominally pure gold to a specific geometry. Within these confined templates of amorphous materials, faceted silicon crystals have been grown laterally. The novel deposition technique, which enables the nominally pure gold catalyst, involves the undercutting of an initial chromium adhesion layer. Using electron backscatter diffraction it was found that silicon nucleated in these micro-crucibles were 30% single crystals, 45% potentially twinned crystals and 25% polycrystals for the experimental conditions used. Single, potentially twinned, and polycrystals all had an aversion to growth with the {1 0 0} surface parallel to the amorphous substrate. Closer analysis of grain boundaries of potentially twinned and polycrystalline samples revealed that the overwhelming majority of them were of the 60° Σ3 coherent twin boundary type. The large amount of coherent twin boundaries present in the grown, two-dimensional silicon crystals suggest that lateral VLS growth occurs very close to thermodynamic equilibrium. It is suggested that free energy fluctuations during growth or cooling, and impurities were the causes for this twinning.

On the growth of CH3NH3PbI3-xClx single crystal and characterization

NASA Astrophysics Data System (ADS)

Su, J.; Wang, W. F.; Lei, Y.; Zhang, L.; Xu, L. H.; Wang, D.; Lu, D.; Bai, Y.

2018-05-01

In this paper, CH3NH3PbI3-xClx crystal was grown by solution cooling method with CH3NH3I and PbCl2 as raw materials. Lead compounds and CH3NH3PbI3-xClx crystal with size about 6 mm × 4 mm × 2 mm were obtained. The chemical reactions with different CH3NH3I/PbCl2 ratios were analyzed. XPS shows the content of chlorine in CH3NH3PbI3-xClx is about 0.91%. PXRD, FT-IR, Raman and absorbance spectra were used to study the structure and optical properties of CH3NH3PbI3-xClx by comparing with CH3NH3PbI3 crystal. The CH3NH3PbI3-xClx crystal grown is of tetragonal structure with the lattice constants a = b = 8.8165 Å, c = 12.7920 Å and the bandgap value of 1.57 eV.

Growth of Solid Solution Crystals

NASA Technical Reports Server (NTRS)

Lehoczky, S. L.; Szofran, F. R.; Holland, L. R.

1985-01-01

The major objective of this program is to determine the conditions under which single crystals of solid solutions can be grown from the melt in a Bridgman configuration with a high degree of chemical homogeneity. The central aim is to assess the role of gravity in the growth process and to explore the possible advantages for growth in the absence of gravity. The alloy system being investigated is the solid solution semiconductor with x-values appropriate for infrared detector applications in Hg sub (1-x) Cd sub x Te the 8 to 14 micro m wavelength region. Both melt and Te-solvent growth are being considered. The study consists of an extensive ground-based experimental and theoretical research effort followed by flight experimentation where appropriate. Experimental facilities have been established for the purification, casting, and crystal growth of the alloy system. Facilities have been also established for the metallurgical, compositional, electric and optical characterization of the alloys. Crystals are being grown by the Bridgman-Stockbarger method and are analyzed by various experimental techniques to evaluate the effects of growth conditions on the longitudinal and radial compositional variations and defect densities in the crystals.

A novel magneto-optical crystal Yb:TbVO4

NASA Astrophysics Data System (ADS)

Zhu, Xianchao; Tu, Heng; Hu, Zhanggui

2018-04-01

Highly transparent Yb:TbVO4 single crystal with dimensions of Ø27 × 41 mm3 alomost without scattering defects has been successfully grown by Czochralski technique. The spectra, thermal properties and laser-induced damage threshold were investigated in detailed. The Faraday rotation (FR) measurement was carried out by means of extinction method. The Verdet constant comes up to 80 rad m-1 T-1 at 1064 nm, significantly larger than TbVO4 (58 rad m-1 T-1) and TGG (40 rad m-1 T-1) reported. Meanwhile, the as-grown crystal presents lower absorption coefficient and higher magneto-optical figure of merit at measured wavelength in comparison with TGG. Moreover, the crystal exhibits a substantially improved extinction ratio (42 dB) in contrast with TbVO4 (29 dB), and exceeds the highest value of TGG (40 dB). These advantages make Yb:TbVO4 a highly promising magneto-optical material candidate for optical isolators in the visible-near infrared region.

Spectroscopic and DFT-based computational studies on the molecular electronic structural characteristics and the third-order nonlinear property of an organic NLO crystal: (E)-N‧-(4-chlorobenzylidene)-4-methylbenzenesulfonohydrazide

NASA Astrophysics Data System (ADS)

Sasikala, V.; Sajan, D.; Joseph, Lynnette; Balaji, J.; Prabu, S.; Srinivasan, P.

2017-04-01

Single crystals of (E)-N‧-(4-chlorobenzylidene)-4-methylbenzenesulfonohydrazide (CBMBSH) have been grown by slow evaporation crystal growth method. The structure stabilizing intramolecular donor-acceptor interactions and the presence of the Nsbnd H⋯O, Csbnd H⋯O and Csbnd H⋯C(π) hydrogen bonds in the crystal were confirmed by vibrational spectroscopic and DFT methods. The linear optical absorption characteristics of the solvent phase of CBMBSH were investigated using UV-Vis-NIR spectroscopic and TD-DFT approaches. The 2PA assisted RSA nonlinear absorption and the optical limiting properties of CBMBSH were studied using the open-aperture Z-scan method. The topological characteristics of the electron density have been determined using the quantum theory of atoms in molecules method.

Habit control of deuterated potassium dihydrogen phosphate crystal for laser applications

NASA Astrophysics Data System (ADS)

Guzman, L. A.; Suzuki, M.; Fujimoto, Y.; Fujioka, K.

2016-03-01

In this study we investigate the habit of partially deuterated potassium dihydrogen phosphate (DKDP) crystals in the presence of Al3+ ions. We have grown single DKDP crystals in (50wt% and 80wt%) partially deuterated solutions and in solutions doped with Al3+ ions (2 ppm) by the point-seed rapid growth technique at controlled supercooling (ΔT=10°C). The growth length of each crystal face was measured and the aspect ratio was calculated. We found that crystals grown in partially deuterated solutions are similar in aspect ratio, while, crystals grown in deuterated solutions doped with Al3+ ions showed a relative change in aspect ratio, the crystal increased in size in the pyramidal direction (vertical axis direction). Crystal characteristics were also analyzed by X-ray diffraction, FTIR and Raman spectroscopy. We have speculated that the relative habit modification is due to a probably adsorption and inclusions of Al3+ ions in the prismatic section of the crystal.

Melt and metallic solution crystal growth of CuInSe 2

NASA Astrophysics Data System (ADS)

Baldus, A.; Benz, K. W.

1993-05-01

In this paper the fabrication of CuInSe 2 chalcopyrite single crystals by the vertical Bridgman technique using non-stoichiometric In 2Se 3-rich congruent composition and a novel ampoule design is describe. Furthermore the growth of CuInSe 2 crystals by the travelling heater method (THM) using an In solvent was investigated. The elemental composition of as-grown CuInSe 2 semiconducting compounds and their electrical properties are discussed and correlated with predictions made by an intrinsic chemistry model.

Crystal growth of carbonate apatite using a CaCO3 flux.

PubMed

Suetsugu, Y; Tanaka, J

1999-09-01

Single crystals of carbonate apatite were grown using a CaCO3 flux under an Ar gas pressure of 55 MPa. The crystals obtained were observed by scanning electron microscopy, optical microscopy and X-ray diffraction. Electron probe microanalyses and thermal analyses were performed. CO3 ions in planar triangle form replaced both OH sites and PO4 tetrahedral sites in the apatite structure: in particular, the OH sites were perfectly substituted by CO3 ions using this method.

Solubility of oxygen in CdS single crystals and their physicochemical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morozova, N. K., E-mail: MorozovaNK@mail.ru; Kanakhin, A. A.; Shnitnikov, A. S.

2016-07-15

The specific features of oxygen dissolution in CdS using the example of single crystals grown by the gas-transport method with deviations from stoichiometry at 1100°C are considered. The effect of various types of intrinsic point defects in crystals of different composition on the form in the presence of oxygen is analyzed. It is shown that the most stable composition thermodynamically is that corresponding to nonstoichiometric “self-activated cadmium sulphide” stabilized with oxygen.

Habit modification of potassium acid phthalate (KAP) single crystals by impurities

NASA Astrophysics Data System (ADS)

Murugakoothan, P.; Mohan Kumar, R.; Ushasree, P. M.; Jayavel, R.; Dhanasekaran, R.; Ramasamy, P.

1999-12-01

Nonlinear optical materials potassium dihydrogen phosphate (KDP), urea and L-arginine phosphate (LAP)-doped KAP crystals were grown by the slow cooling method. The LAP-doped crystals show pronounced habit modification compared to KDP and urea doping. The effect of these impurities on growth kinetics, surface morphology, habit modification, structure, optical and mechanical properties have been studied. Among the three impurities, urea doping yields high mechanical stability and optical transmission and for KDP and LAP doping there is a decrease in optical transmission.

FNAS/advanced protein crystal growth

NASA Technical Reports Server (NTRS)

Rosenberger, Franz

1992-01-01

A scintillation method is presented for determination of the temperature dependence of the solubility, S(T), of proteins in 50-100 micro-l volumes of solution. S(T) data for lysozyme and horse serum albumin were obtained for various combinations of pH and precipitant concentrations. The resulting kinetics and equilibrium information was used for dynamic control, that is the separation of nucleation and growth stages in protein crystallization. Individual lysozyme and horse serum albumin crystals were grown in 15-20 micro-l solution volumes contained in x-ray capillaries.

Solid Solution, Mass Transport, and Crystal Growth Studies of Cadmium Iron Selenide.

NASA Astrophysics Data System (ADS)

Huang, Xuejun

Cadmium iron selenide, a semimagnetic semiconductor, has been investigated. Solid solubilities of iron in CdSe were determined at temperatures between 650^ circC and 1100^circC, using the X-ray diffraction Debye-Scherrer powder technique. The solubility limits of Fe in CdSe increase with the temperatures to reach a maximum of about 19.5 mole % FeSe_ {1.24} at 925^circ C, and then decrease with further increasing temperature. Solidification phenomena of the Cd-Fe-Se solid solutions were observed employing optical microscopy, which reveals a typical divorced, eutectic type, nonequilibrium solidification. The combination of the X-ray diffraction and the microscopic investigations yielded a pseudo-binary, eutectic type phase diagram of the Cd-Fe-Se system. Partial pressures of the major vapor species in the Cd-Fe-Se physical and the Cd-Fe-Se-Iodine chemical vapor transport systems were calculated. The partial pressure of gaseous iron species of the PVT system may be neglected compared to those of Cd and Se_2^ecies. This suggests that cadmium iron selenide crystals cannot be grown by the PVT method. For the PVT experiments, using the as-synthesized (CdSe)_ {0.90}(FeSe_{1.24})_{0.10 } source materials, crystals with compositions of 6-8 mole % FeSe_{1.24} were grown at a source temperature of 1000^ circC and a DeltaT of 12^circC. These result are contradictory to the thermodynamic predictions, and were further investigated employing specially purified source materials. Iron contents in the crystals grown in these experiments are close to zero. The transport of iron in the initial mass transport experiments may be due to the chemical impurities (most likely the metal chlorides) in the as-synthesized source materials. Mass transport experiments of the Cd-Fe-Se-Iodine CVT system were performed as a function of source temperatures, the degrees of undercooling (DeltaT), and initial iodine pressures. Promising parameters for the growth of cadmium iron selenide single crystals by the CVT method, e.g., the source temperatures of 800-850 ^circC, initial iodine pressures of 0.5-1.0 atm, and DeltaT of 10 -20^circC, were established. Mass fluxes of cadmium iron selenide were computed using a one -dimensional diffusion equation. The overall trends of the computed mass flux as a function of growth conditions are consistent with the experimental results. However, differences between the theoretical and experimental mass fluxes may be due to the uncertainties of the thermochemical data used and the approximations made in these estimations. Single crystals of cadmium iron selenide with compositions of 6.5-8.5 mole % FeSe_{1.24 } and of about 5 mm edge lengths were successfully grown from the (CdSe)_{0.90 }(FeSe_{1.24})_{0.10} source materials by the CVT method. Compositions of various portions of the bulk crystals are nearly constant along its axis within the error limits, indicating that the crystals possess reasonable compositional uniformity. The indices of the crystal surfaces were obtained by the X -ray diffraction Laue method. The (0001) and (1011) planes usually developed as the natural facets on the surfaces, and (1010) and(1120) as the cleavage planes. A promising chemical etchant for cadmium iron selenide crystals was developed, consisting of about 20 vol. % concentrated HNO_3, 60 vol. % glacial CH _3COOH, and 20 vol. % concentrated H _2SO_4 acids. Etch pit densities of the grown crystals are in the range of 5times10 ^4-rm5times10^5/cm ^2..

Growth and characterization of SrI2:Eu2+ single crystal for gamma ray detector applications

NASA Astrophysics Data System (ADS)

Raja, A.; Daniel, D. Joseph; Ramasamy, P.; Singh, S. G.; Sen, S.; Gadkari, S. C.

2018-04-01

Europium activated Strontium Iodide single crystal was grown by vertical Bridgman-stockbarger technique. The melting point and freezing point of SrI2:Eu2+ crystal was analyzed by TG/DTA. The Radioluminescence emission was recorded. The scintillation measurement was carried out for the grown SrI2:Eu2+ crystal under 137Cs gamma energy source.

Tl{sub 10}Hg{sub 3}Cl{sub 16}: Single crystal growth, electronic structure and piezoelectric properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khyzhun, O.Y., E-mail: khyzhun@ipms.kiev.ua; Piasecki, M.; Kityk, I.V.

Single crystal of the ternary halide Tl{sub 10}Hg{sub 3}Cl{sub 16} was grown using Bridgman-Stockbarger method. For the Tl{sub 10}Hg{sub 3}Cl{sub 16} crystal, we have measured X-ray photoelectron spectra for both pristine and Ar{sup +} ion-bombarded surfaces and additionally investigated photoinduced piezoelectricity. Our data indicate that the Tl{sub 10}Hg{sub 3}Cl{sub 16} single crystal surface is very sensitive with respect to Ar{sup +} ion-bombardment. In particular, Ar{sup +} ion-bombardment with energy of 3.0 keV over 5 min at an ion current density of 14 μA/cm{sup 2} causes significant changes of the elemental stoichiometry of the Tl{sub 10}Hg{sub 3}Cl{sub 16} surface resulting inmore » an abrupt decrease of the mercury content in the top surface layers of the studied single crystal. As a result of the treatment, the mercury content becomes nil in the top surface layers. In addition, the present XPS measurements allow for concluding about very low hygroscopicity of the Tl{sub 10}Hg{sub 3}Cl{sub 16} single crystal surface. The property is extremely important for the crystal handling in optoelectronic or nano-electronic devices working at ambient conditions. The photoinduced piezoelectricity has been explored for Tl{sub 10}Hg{sub 3}Cl{sub 16} depending on nitrogen (λ=371 nm) laser power density and temperature. - Graphical abstract: As-grown single crystal boule of Tl{sub 10}Hg{sub 3}Cl{sub 16}; dependence of the effective piezoelecric coefficient d{sub 33} versus the photoinducing nitrogen laser power density, I, at different temperatures, T; and packing of the polyhedra of halide atoms around Hg atoms in the Tl{sub 10}Hg{sub 3}Cl{sub 16} structure. - Highlights: • High-quality Tl{sub 10}Hg{sub 3}Cl{sub 16} single crystal has been grown by Bridgman-Stockbarger method. • Electronic structure of Tl{sub 10}Hg{sub 3}Cl{sub 16} is studied by the XPS method. • Tl{sub 10}Hg{sub 3}Cl{sub 16} single crystal surface is sensitive with respect to Ar{sup +} ion-bombardment. • Very low hygroscopicity is characteristic of the Tl{sub 10}Hg{sub 3}Cl{sub 16} surface. • Photoinduced piezoelectricity is studied for the Tl{sub 10}Hg{sub 3}Cl{sub 16} compound.« less

Electrooptic crystal growth and properties

NASA Astrophysics Data System (ADS)

1994-02-01

A new member in the tungsten-bronze family of ferroelectric lead potassium niobate (PKN), with general formula Pb(1-x)K(2x)Nb2O6, has been grown as bulk single crystal. Growth of PKN with charge composition x = 0.23 has been achieved using the Czochralski technique of crystal pulling. Large diameter boules were grown in platinum crucibles at temperatures between 1280 and 1300 C. Crystallographic studies were conducted using x ray diffraction techniques. The samples were characterized for ferroelectric properties between 25 and 600 C and for optical absorption. This paper presents the crystal synthesis and the results of ferroelectric and optical characterization. Bulk single crystals of potassium tantalate niobate, KTa(1-x)Nb(x)O3, ferroelectric with different values of Ta/Nb ratios have been grown by temperature gradient transport technique (TGTT). A second attached paper presents the results of the crystal growth experiments, ferroelectric characterization techniques, and properties of potassium tantalate niobate crystals.

Structural and photoluminescence studies on europium-doped lithium tetraborate (Eu:Li2B4O7) single crystal grown by microtube Czochralski (μT-Cz) technique

NASA Astrophysics Data System (ADS)

A, Kumaresh; R, Arun Kumar; N, Ravikumar; U, Madhusoodanan; B, S. Panigrahi; K, Marimuthu; M, Anuradha

2016-05-01

Rare earth europium (Eu3+)-doped lithium tetraborate (Eu:Li2B4O7) crystal is grown from its stoichiometric melt by microtube Czochralski pulling technique (μT-Cz) for the first time. The grown crystals are subjected to powder x-ray diffraction (PXRD) analysis which reveals the tetragonal crystal structure of the crystals. UV-vis-NIR spectral analysis is carried out to study the optical characteristics of the grown crystals. The crystal is transparent in the entire visible region, and the lower cutoff is observed to be at 304 nm. The existence of BO3 and BO4 bonding structure and the molecular associations are analyzed by Fourier transform infrared (FTIR) spectroscopy. The results of excitation and emission-photoluminescence spectra of europium ion incorporated in lithium tetraborate (LTB) single crystal reveal that the observations of peaks at 258, 297, and 318 nm in the excitation spectra and peaks at 579, 591, 597, 613, and 651 nm are observed in the emission spectra. The chromaticity coordinates are calculated from the emission spectra, and the emission intensity of the grown crystal is characterized through a CIE 1931 (Commission International d’Eclairage) color chromaticity diagram. Project supported by the Department of Science and Technology-Science and Engineering Research Board (Grant No. SR/S2/LOP-0012/2011), the Government of India for Awarding Major Research Project, the University Grants Commission-Department of Atomic Research-Consortium for Scientific Research (Grant No. CSR-KN/CSR-63/2014-2015/503), and the Kalpakkam and Indore, India.

Numerical simulation of flow and mass transfer for large KDP crystal growth via solution-jet method

NASA Astrophysics Data System (ADS)

Yin, Huawei; Li, Mingwei; Hu, Zhitao; Zhou, Chuan; Li, Zhiwei

2018-06-01

A novel technique of growing large crystals of potassium dihydrogen phosphate (KDP) named solution-jet method is proposed. The aim is to increase supersaturation on the pyramidal face, especially for crystal surface regions close to the rotation axis. The fluid flow and surface supersaturation distribution of crystals grown under different conditions were computed using the finite-volume method. Results indicate that the time-averaged supersaturation of the pyramidal face in the proposed method significantly increases and the supersaturation difference from the crystal center to edge clearly decreases compared with the rotating-crystal method. With increased jet velocity, supersaturation on the pyramidal face steadily increases. Rotation rate considerably affects the magnitude and distribution of the prismatic surface supersaturation. With increased crystal size, the mean value of surface supersaturation averaged over the pyramid gradually decreases; conversely, standard deviation increases, which is detrimental to crystal growth. Moreover, the significant roles played by natural and forced convection in the process of mass transport are discussed. Results show that further increased jet velocity to 0.6 m/s renders negligible the effects of natural convection around the pyramid. The simulation for step propagation indicates that solution-jet method can promote a steady step migration and enhance surface morphology stability, which can improve the crystal quality.

Molecule diagram from space-grown crystals

NASA Technical Reports Server (NTRS)

2004-01-01

Researchers' at Hauptman-Woodward Medical Research Institute, in Buffalo, N.Y. have analyzed the molecular structures of insulin crystals grown during Space Shuttle experiments and are unlocking the mystery of how insulin works.

Microgravity

NASA Image and Video Library

1995-01-01

This image shows crystals of the protein raf kinase grown on Earth (photo a) and on USML-2 (photo b). The space-grown crystals are an order of magnitude larger. Principal Investigator: Dan Carter of New Century Pharmaceuticals

A novel microseeding method for the crystallization of membrane proteins in lipidic cubic phase.

PubMed

Kolek, Stefan Andrew; Bräuning, Bastian; Stewart, Patrick Douglas Shaw

2016-04-01

Random microseed matrix screening (rMMS), in which seed crystals are added to random crystallization screens, is an important breakthrough in soluble protein crystallization that increases the number of crystallization hits that are available for optimization. This greatly increases the number of soluble protein structures generated every year by typical structural biology laboratories. Inspired by this success, rMMS has been adapted to the crystallization of membrane proteins, making LCP seed stock by scaling up LCP crystallization conditions without changing the physical and chemical parameters that are critical for crystallization. Seed crystals are grown directly in LCP and, as with conventional rMMS, a seeding experiment is combined with an additive experiment. The new method was used with the bacterial integral membrane protein OmpF, and it was found that it increased the number of crystallization hits by almost an order of magnitude: without microseeding one new hit was found, whereas with LCP-rMMS eight new hits were found. It is anticipated that this new method will lead to better diffracting crystals of membrane proteins. A method of generating seed gradients, which allows the LCP seed stock to be diluted and the number of crystals in each LCP bolus to be reduced, if required for optimization, is also demonstrated.

Characterization of potassium bromide crystals grown in the aqueous solution of picric acid

NASA Astrophysics Data System (ADS)

Maheswari, J. Uma; Krishnan, C.; Kalyanaraman, S.; Selvarajan, P.

2016-12-01

Potassium bromide crystals were grown in the aqueous solution of picric acid by slow evaporation technique at room temperature. X-ray Diffraction (XRD) analysis ensures that the grown sample is in Fm3m space group and FCC structure. Energy Dispersive X-ray Spectroscopy (EDX) reveals the presence of elements in the title compound. UV-Vis-NIR spectrum reveals that the grown sample is a promising nonlinear optical (NLO) material. FTIR analysis confirms the functional groups present in the sample. The thermogravimetric (TG) and differential thermogravimetric (DTA) analyses ensure that the sample material is thermally stable up to 160 °C. The second harmonic efficiency of the sample is 1.3 times greater than that of standard KDP. The mechanical strength of the grown sample is estimated by Vickers microhardness tester. The electrical properties were investigated by impedance analysis and the results of various studies of the grown crystals are discussed.

Photorefractivity in a Titanium Doped ZnCdTe Crystal

NASA Technical Reports Server (NTRS)

Davis, M.; Collins, L.; Dyer, K.; Tong, J.; Ueda, A.; Chen, H.; Chen, K.-T.; Burger, A.; Pan, Z.; Morgan, S. H.

1997-01-01

Single crystals of Zn(.04)Cd(.96)Te was grown by horizontal physical vapor transport (PVT) method and doped by annealing with TiTe2 powder at 600 C for six days. Photorefractive two-beam coupling, along with photoluminescence and absorption spectroscopy, were used to characterize the ZnCdTe:Ti crystal. At 1.32 micrometers, the photorefractive gain has been measured as a function of the grating period. A gain of about 0.16/cm was obtained at an intensity of about 0.1 W/sq cm. The results of this titanium doped ZnCdTe crystal are compared to that of vanadium-doped CdTe crystals reported previously.

Antimicrobial activity and second harmonic studies on organic non-centrosymmetric pure and doped ninhydrin single crystals

NASA Astrophysics Data System (ADS)

Prasanyaa, T.; Jayaramakrishnan, V.; Haris, M.

2013-03-01

In this paper, we report the successful growth of pure, Cu2+ ions and Cd2+ ions doped on ninhydrin single crystals by slow solvent evaporation technique. The presence of Cu2+ and Cd2+ ions in the specimen of ninhydrin single crystal has been determined by atomic absorption spectroscopy. The powder X-ray diffraction analysis was done to calculate the lattice parameters of the pure and doped crystals. The percentage of transmittance of the crystal was recorded using the UV-Vis Spectrophotometer. Thermal behaviors of the grown crystals have been examined by the thermal gravimetric/differential thermal analysis. The hardness of the grown crystals was assessed and the results show the minor variation in the hardness value for the pure and doped ninhydrin samples. The value of the work hardening coefficient n was found to be 2.0, 1.0 and 1.06 for pure, copper and cadmium doped ninhydrin crystals respectively. The second harmonic generation efficiency of Cd2+ and Cu2+ doped ninhydrin is 8.3 and 6.3 times greater than well known nonlinear crystal of potassium dihydrogen phosphate respectively. The antibacterial and antifungal activities of the title compound were performed by disk diffusion method against the standard bacteria Escherichia coli, Xanthomonas oryzae and against the fungus Aspergillis niger and Aspergillus flavus.

Growth and characterization of an organic single crystal: 2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide

NASA Astrophysics Data System (ADS)

Senthil, K.; Kalainathan, S.; Ruban Kumar, A.

Optically transparent crystal of the organic salt DEASI (2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide) has been synthesized by using knoevenagel condensation reaction method. The synthesized material has been purified by successfully recrystallization process. Single crystals of DEASI have been grown by slow evaporation technique at room temperature. The solubility of the title material has been determined at different temperature in acetonitrile/methanol mixture. The cell parameters and crystallinity of the title crystal were determined by single crystal XRD. The powder diffraction was carried out to study the reflection plane of the grown crystal and diffraction peaks were indexed. The presence of different functional groups in the crystal was confirmed by Fourier transform infrared (FTIR) analysis. 1H NMR spectrum was recorded to confirm the presence of hydrogen nuclei in the synthesized material. The optical property of the title crystal was studied by UV-Vis-NIR spectroscopic analysis. The melting point and thermal property of DEASI were studied using TGA/DSC technique. The Vicker’s hardness (Hv) was carried out to know the category. The dielectric constant and dielectric loss of the compound decreases with an increase in frequencies. Chemical etching studies showed that the DEASI grows in the two dimensional growth mechanisms. The Kurtz-Perry powder second harmonic generation (SHG) test has done for title crystal.

Antimicrobial activity and second harmonic studies on organic non-centrosymmetric pure and doped ninhydrin single crystals.

PubMed

Prasanyaa, T; Jayaramakrishnan, V; Haris, M

2013-03-01

In this paper, we report the successful growth of pure, Cu(2+) ions and Cd(2+) ions doped on ninhydrin single crystals by slow solvent evaporation technique. The presence of Cu(2+) and Cd(2+) ions in the specimen of ninhydrin single crystal has been determined by atomic absorption spectroscopy. The powder X-ray diffraction analysis was done to calculate the lattice parameters of the pure and doped crystals. The percentage of transmittance of the crystal was recorded using the UV-Vis Spectrophotometer. Thermal behaviors of the grown crystals have been examined by the thermal gravimetric/differential thermal analysis. The hardness of the grown crystals was assessed and the results show the minor variation in the hardness value for the pure and doped ninhydrin samples. The value of the work hardening coefficient n was found to be 2.0, 1.0 and 1.06 for pure, copper and cadmium doped ninhydrin crystals respectively. The second harmonic generation efficiency of Cd(2+) and Cu(2+) doped ninhydrin is 8.3 and 6.3 times greater than well known nonlinear crystal of potassium dihydrogen phosphate respectively. The antibacterial and antifungal activities of the title compound were performed by disk diffusion method against the standard bacteria Escherichia coli, Xanthomonas oryzae and against the fungus Aspergillis niger and Aspergillus flavus. Copyright © 2012 Elsevier B.V. All rights reserved.

Growth and characterization of an organic single crystal: 2-[2-(4-diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide.

PubMed

Senthil, K; Kalainathan, S; Ruban Kumar, A

2014-05-05

Optically transparent crystal of the organic salt DEASI (2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide) has been synthesized by using knoevenagel condensation reaction method. The synthesized material has been purified by successfully recrystallization process. Single crystals of DEASI have been grown by slow evaporation technique at room temperature. The solubility of the title material has been determined at different temperature in acetonitrile/methanol mixture. The cell parameters and crystallinity of the title crystal were determined by single crystal XRD. The powder diffraction was carried out to study the reflection plane of the grown crystal and diffraction peaks were indexed. The presence of different functional groups in the crystal was confirmed by Fourier transform infrared (FTIR) analysis. (1)H NMR spectrum was recorded to confirm the presence of hydrogen nuclei in the synthesized material. The optical property of the title crystal was studied by UV-Vis-NIR spectroscopic analysis. The melting point and thermal property of DEASI were studied using TGA/DSC technique. The Vicker's hardness (Hv) was carried out to know the category. The dielectric constant and dielectric loss of the compound decreases with an increase in frequencies. Chemical etching studies showed that the DEASI grows in the two dimensional growth mechanisms. The Kurtz-Perry powder second harmonic generation (SHG) test has done for title crystal. Copyright © 2014 Elsevier B.V. All rights reserved.

Simulation of the temperature distribution in crystals grown by Czochralski method

NASA Technical Reports Server (NTRS)

Dudokovic, M. P.; Ramachandran, P. A.

1985-01-01

Production of perfect crystals, free of residual strain and dislocations and with prescribed dopant concentration, by the Czochralski method is possible only if the complex, interacting phenomena that affect crystal growth in a Cz-puller are fully understood and quantified. Natural and forced convection in the melt, thermocapillary effect and heat transfer in and around the crystal affect its growth rate, the shape of the crystal-melt interface and the temperature gradients in the crystal. The heat transfer problem in the crystal and between the crystal and all other surfaces present in the crystal pulling apparatus are discussed at length. A simulation and computer algorithm are used, based on the following assumptions: (1) only conduction occurs in the crystal (experimentally determined conductivity as a function of temperature is used), (2) melt temperature and the melt-crystal heat transfer coefficient are available (either as constant values or functions of radial position), (3) pseudo-steady state is achieved with respect to temperature gradients, (4) crystal radius is fixed, and (5) both direct and reflected radiation exchange occurs among all surfaces at various temperatures in the crystal puller enclosure.

Cupric oxide inclusions in cuprous oxide crystals grown by the floating zone method

NASA Astrophysics Data System (ADS)

Frazer, Laszlo; Chang, Kelvin B.; Poeppelmeier, Kenneth R.; Ketterson, John B.

2015-06-01

Phase-pure cuprous oxide (Cu2O) crystals are difficult to grow since cupric oxide can form within the crystal as the crystal is cooled to ambient conditions. Vacancies are the solute which causes precipitation of macroscopic defects. Therefore, even when a mostly phase-pure single crystal is used as a feed rod, cupric oxide inclusions persist in the recrystallized solid. Control of the thermal profile during crystal growth, however, can improve phase-purity; a slow counter-rotation rate of the feed and seed rods results in fewer inclusions. Cupric oxide can be removed by annealing, which produces a factor of 540 ± 70 increase in phase-purity.

Cupric oxide inclusions in cuprous oxide crystals grown by the floating zone method

PubMed Central

Frazer, Laszlo; Chang, Kelvin B; Poeppelmeier, Kenneth R; Ketterson, John B

2015-01-01

Phase-pure cuprous oxide (Cu2O) crystals are difficult to grow since cupric oxide can form within the crystal as the crystal is cooled to ambient conditions. Vacancies are the solute which causes precipitation of macroscopic defects. Therefore, even when a mostly phase-pure single crystal is used as a feed rod, cupric oxide inclusions persist in the recrystallized solid. Control of the thermal profile during crystal growth, however, can improve phase-purity; a slow counter-rotation rate of the feed and seed rods results in fewer inclusions. Cupric oxide can be removed by annealing, which produces a factor of 540 ± 70 increase in phase-purity. PMID:27877798

Crystal growth, structural, optical, spectral and thermal studies of tris( L-phenylalanine) L-phenylalaninium nitrate: A new organic nonlinear optical material

NASA Astrophysics Data System (ADS)

Prakash, M.; Geetha, D.; Lydia Caroline, M.

2011-10-01

Tris( L-phenylalanine) L-phenylalaninium nitrate, C 9H 12NO 2+·NO 3-·3C 9H 11NO 2 (TPLPN), a new organic nonlinear optical material was grown from aqueous solution by slow evaporation solution growth at room temperature. The grown crystals were subjected to powder X-ray diffraction and single crystal X-ray diffraction studies to confirm the crystalline nature and crystal structure. The modes of vibration of different molecular groups present in TPLPN have been identified by FTIR spectral analysis. The presence of hydrogen and carbon in the grown crystal were confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. The optical transmission spectral study establishes good transmitting ability of the crystal in the entire visible region. The thermogravimetric (TG) and differential thermal analyses (DTA) were carried out to understand the thermal stability of the sample. The nonlinear optical property of the compound observed using Kurtz powder second harmonic generation test assets the suitability of the grown material for the frequency conversion of laser radiation of Nd:YAG.

Magnetic structure and phase stability of the van der Waals bonded ferromagnet Fe 3-xGeTe 2

DOE PAGES

May, Andrew F.; Calder, Stuart A.; Cantoni, Claudia; ...

2016-01-08

The magnetic structure and phase diagram of the layered ferromagnetic compound Fe 3GeTe 2 have been investigated by a combination of synthesis, x-ray and neutron diffraction, high-resolution microscopy, and magnetization measurements. Single crystals were synthesized by self-flux reactions, and single-crystal neutron diffraction finds ferromagnetic order with moments of 1.11(5)μ B/Fe aligned along the c axis at 4 K. These flux-grown crystals have a lower Curie temperature T c ≈ 150 K than crystals previously grown by vapor transport (T c = 220 K). The difference is a reduced Fe content in the flux-grown crystals, as illustrated by the behavior observedmore » in a series of polycrystalline samples. As Fe content decreases, so do the Curie temperature, magnetic anisotropy, and net magnetization. Furthermore, Hall-effect and thermoelectric measurements on flux-grown crystals suggest that multiple carrier types contribute to electrical transport in Fe 3–xGeTe 2 and structurally similar Ni 3–xGeTe 2.« less

Impact of Substrate Types on Structure and Emission of ZnO Nanocrystalline Films

NASA Astrophysics Data System (ADS)

Ballardo Rodriguez, I. Ch.; El Filali, B.; Díaz Cano, A. I.; Torchynska, T. V.

2018-02-01

Zinc oxide (ZnO) films were simultaneously synthesized by an ultrasonic spray pyrolysis (USP) method on p-type Si (100), silicon carbide polytype [6H-SiC (0001)], porous 6H-SiC and amorphous glass substrates with the aim of studying the impact of substrate types on the structure and emission of ZnO nanocrystalline films. Porous silicon carbide (P-SiC) was prepared by the electrochemical anodization method at a constant potential of 20 V and etching time of 12 min. ZnO films grown on the SiC and P-SiC substrates are characterized by a wurtzite crystal structure with preferential growth along the (002) direction and with grain sizes of 90-180 and 70-160 nm, respectively. ZnO films grown on the Si substrate have just some small irregular hexagonal islands. The amorphous glass substrate did not promote the formation of any regular crystal forms. The obtained x-ray diffraction and photoluminescence (PL) results have shown that the better ZnO film crystallinity and high PL intensity of near-band edge emissions were achieved in the films grown on the porous SiC and SiC substrates. The preferential growth and crystalline nature of ZnO films on the SiC substrate have been discussed from the point of view of the lattice parameter compatibility between ZnO and SiC crystals.

Influence of disorder on the signature of the pseudogap and multigap superconducting behavior in FeSe

NASA Astrophysics Data System (ADS)

Rößler, Sahana; Huang, Chien-Lung; Jiao, Lin; Koz, Cevriye; Schwarz, Ulrich; Wirth, Steffen

2018-03-01

We investigated several FeSe single crystals grown by two different methods by utilizing experimental techniques, namely, resistivity, magnetoresistance, specific heat, scanning tunneling microscopy, and spectroscopy. The residual resistivity ratio (RRR) shows systematic differences between samples grown by chemical vapor transport and flux vapor transport, indicating variance in the amount of scattering centers. Although the superconducting transition temperature Tc is not directly related to RRR, our study evidences subtle differences in the features of an incipient ordering mode related to a depletion of density of states at the Fermi level. For instance, the onset temperature of anisotropic spin fluctuations at T*≈75 K, and the temperature of the opening up of a partial gap in the density of states at T**≈30 K, are not discernible in the samples with lower RRR. Further, we show that the functional dependence of the electronic specific heat below 2 K, which allows us to determine the nodal features as well as the small superconducting gap, differs significantly in crystals grown by these two different methods. Our investigation suggests that some of the controversies about the driving mechanism for the superconducting gap or its structure and symmetry are related to minute differences in the crystals arising due to the growth techniques used and the total amount of scattering centers present in the sample.

Nanostructures of Indium Gallium Nitride Crystals Grown on Carbon Nanotubes.

PubMed

Park, Ji-Yeon; Man Song, Keun; Min, Yo-Sep; Choi, Chel-Jong; Seok Kim, Yoon; Lee, Sung-Nam

2015-11-16

Nanostructure (NS) InGaN crystals were grown on carbon nanotubes (CNTs) using metalorganic chemical vapor deposition. The NS-InGaN crystals, grown on a ~5-μm-long CNT/Si template, were estimated to be ~100-270 nm in size. Transmission electron microscope examinations revealed that single-crystalline InGaN NSs were formed with different crystal facets. The observed green (~500 nm) cathodoluminescence (CL) emission was consistent with the surface image of the NS-InGaN crystallites, indicating excellent optical properties of the InGaN NSs on CNTs. Moreover, the CL spectrum of InGaN NSs showed a broad emission band from 490 to 600 nm. Based on these results, we believe that InGaN NSs grown on CNTs could aid in overcoming the green gap in LED technologies.

Research on growth and defects of 5 in. YCOB single crystal

NASA Astrophysics Data System (ADS)

Tu, Xiaoniu; Wang, Sheng; Xiong, Kainan; Zheng, Yanqing; Shi, Erwei

2018-04-01

YCa4O(BO3)3 (YCOB) is an important nonlinear optical crystal, which is a key optical element in the SHG and OPCPA process to obtain high repetition rate, multi-petawatt laser pulse. In this work, we have grown 5 in. YCOB crystals by Czochralski method and investigated phase separation, defects, as well as their formation mechanism. Laser induced damage threshold (LiDT), rocking curve and transmission spectrum is characterized using the sample without defects. It is believed that, based on this work, large-sized YCOB crystal without defects will be obtained in the near future.

Studies on growth, thermal, optical, vibrational properties and hyperpolarizability of a complex orthonitroaniline with picric acid

NASA Astrophysics Data System (ADS)

Anandhi, S.; Shyju, T. S.; Gopalakrishnan, R.

2010-11-01

The present article reports the growth of single crystals of a complex Orthonitroaniline with picric acid (2[C 6H 6N 2O 2]·C 6H 2(NO 2) 3OH) (ONAP) by solution growth (slow evaporation) method at room temperature. Single crystal XRD, UV-vis spectral analysis and TGA/DTA studies were carried out. FT-IR and Raman spectra were recorded to explore information of the functional groups. The high-resolution X-ray diffraction curve reveals the internal structural low angle boundaries. The PL spectrum of the title compound shows green emission. Dielectric behaviour was investigated at 33 and 70 °C. The dipole moment and first-order hyperpolarizability ( β) values were evaluated by using Gaussian 98 W software package with the help of B3LYP the density functional theory (DFT) method. The possible modes of vibrations are theoretically predicted by factor group analysis. The mechanical stability of the grown crystal was tested with Vicker's microhardness tester and the work hardening coefficient of the grown material was estimated.

Spherical crystals of Pb 1 - xSn xTe grown in microgravity

NASA Astrophysics Data System (ADS)

Kinoshita, Kyoichi; Yamada, Tomoaki

1996-07-01

Pb 1- xSn xTe spherical crystals were unintentionally obtained along with a cylindrical Pb 1 - xSn xTe crystal grown during the {SL-J}/{FMPT} mission on board the space shuttle "Endeavor". About 25 spherical crystals ranged from 0.5 to 11 mm in diameter. Melt leaked from the melt reservoir into the spring that plays the role of pushing the melt toward a seed crystal and eliminating free surface areas of the melt. Because of the surface tension of the melt, spherical melt drops formed in the hollow of the spring, then solidified into spherical crystals during the cooling process. Some of the crystals had lower dislocation densities, in the order of 10 4 cm -2, two orders smaller than those of terrestrially grown crystals from a melt. The experiment showed a way of stably positioning a large volume of liquid in microgravity without touching the crucible wall and a way of reducing crystalline defects by such growth.

Structural analysis of benzothienobenzothiophene-based soluble organic semiconducting crystals grown by liquid crystal solvent

NASA Astrophysics Data System (ADS)

Shibata, Yosei; Matsuzaki, Tomoya; Ishinabe, Takahiro; Fujikake, Hideo

2018-06-01

In this study, we analyzed organic semiconducting single crystals composed of benzothienobenzothiophene derivatives (2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene, C8-BTBT) grown by nematic-phase liquid crystal (LC) solvent. As a result, we clarified that the crystal b-axis direction of the C8-BTBT single crystals was consistent with the LC alignment direction. By optical evaluation and simulation based on density functional theory, we found that the C8-BTBT single crystals in LC solvent exhibited a novel molecular conformation having alkyl chains oriented toward the b-axis.

Is it Possible to have the Similar Unit Cell in Crystals of Different form from the same Macromolecule? (A Case Study of Ribosome Crystals)

NASA Technical Reports Server (NTRS)

Karpova, E. A.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Three different types of ribosome crystals were grown by the vapor diffusion technique in hanging drops as described in (1,2). The ribosome is a large asymmetric RNA-protein complex (2.3 million Da), which is protein syntheses machinery of the cell. In this poster we would like to discuss the features of ribosome crystallization. Ribosomes were purified from the thermophilic bacteria Thermus thermophilus by centrifugation (3). Three types of crystals (needle, flat tetragonal and tetragonal-like pyramid) can be grown from the same solution; furthermore, in the same drop using 10-15% 2-methyl-2,4- pentanediol as a precipitant. The crystals appeared in 5-48 hours. The crystals were stable and can co-exist in solution over long period of time. The kinetics of appearance of different crystal forms was different: first the needle crystals were grown, then the tetragonal, and finally the tetragonal pyramids. Later studies of the process of ribosome crystal growth depending on supersaturation showed that low supersaturation results in the appearance of tetragonal plates or tetragonal-like pyramids. An electron microscopy study, together with computer modeling, has shown that crystals of different forms have a high probability of having the same unit cell parameters. According to these experiments the following conclusion can be dranvn: the level of supersaturation of the macromolecule in a crystallizing solution is one of the major factors for forming three-dimensional crystals convenient for X-rays diffraction analysis. From the same macromolecule solution, crystals of different forms can be grown at approximately the same conditions by varying the concentration of macromolecule in the solution. Ion-macromolecule and water-macromolecule interactions, apparently, play the main role in the formation of the unit cell of the crystals.

Large Area Cd0.9Zn0.1Te Pixelated Detector: Fabrication and Characterization

NASA Astrophysics Data System (ADS)

Chaudhuri, Sandeep K.; Nguyen, Khai; Pak, Rahmi O.; Matei, Liviu; Buliga, Vladimir; Groza, Michael; Burger, Arnold; Mandal, Krishna C.

2014-04-01

Cd0.9Zn0.1Te (CZT) based pixelated radiation detectors have been fabricated and characterized for gamma ray detection. Large area CZT single crystals has been grown using a tellurium solvent method. A 10 ×10 guarded pixelated detector has been fabricated on a 19.5 ×19.5 ×5 mm3 crystal cut out from the grown ingot. The pixel dimensions were 1.3 ×1.3 mm2 and were pitched at 1.8 mm. A guard grid was used to reduce interpixel/inter-electrode leakage. The crystal was characterized in planar configuration using electrical, optical and optoelectronic methods prior to the fabrication of pixelated geometry. Current-voltage (I-V) measurements revealed a leakage current of 27 nA at an operating bias voltage of 1000 V and a resistivity of 3.1 ×1010 Ω-cm. Infrared transmission imaging revealed an average tellurium inclusion/precipitate size less than 8 μm. Pockels measurement has revealed a near-uniform depth-wise distribution of the internal electric field. The mobility-lifetime product in this crystal was calculated to be 6.2 ×10 - 3 cm2/V using alpha ray spectroscopic method. Gamma spectroscopy using a 137Cs source on the pixelated structure showed fully resolved 662 keV gamma peaks for all the pixels, with percentage resolution (FWHM) as high as 1.8%.

Single-crystal growth, structure refinement and the properties of Bis(glycine) Strontium Chloride

NASA Astrophysics Data System (ADS)

Balaji, S. R.; Balu, T.; Rajasekaran, T. R.

2018-02-01

Single crystals of Bis (glycine) Strontium Chloride (BGSC) were grown by means of slow evaporation process by using analar grade Glycine and Strontium Chloride Hexahydrate as a parent compound from its aqueous solution at room temperature. The final chemical composition, [{{Sr}}{({{{C}}}2{{{H}}}5{{{NO}}}2)}2{{{Cl}}}2].{{{H}}}4{{{O}}}3+{{{H}}}8{{{O}}}3, formed were metallic light colorless block, about the size of 28 mm × 9 mm × 8 mm. A single-crystal x-ray diffraction study revealed an ordered superstructure with orthorhombic symmetry that could be assigned to the space group Pbcn. The structure in BGSC, revealed in the electron density distribution was analyzed by the direct methods (SHELXS-2014) and refined by least squares full matrix method (SHELXL-2014). The crystal structure, including anisotropic atomic displacement parameters for each atom and isotropic atomic displacement parameters for hydrogen atom, was refined to R1 = 0.0395, wR2 = 0.0776 using 1097 independent reflections. The FTIR spectrum of BGSC confirms the protonation of amino groups and the different molecular groups present in BGSC vibrate in different modes. Reverse Indentation Size Effect (RISE) was revealed in BGSC in the micro-hardness analysis using Vicker’s micro-hardness analysis. DTA and DSC results ruled out the possibility of structural change independent of mass change. The AFM studies shows fine nano size fiber like structure of the grown crystals.

Human serum albumin crystals and method of preparation

NASA Technical Reports Server (NTRS)

Carter, Daniel C. (Inventor)

1989-01-01

Human serum albumin (HSA) crystals are provided in the form of tetragonal plates having the space groups P42(sub 1)2, the crystals being grown to sizes in excess of 0.5 mm in two dimensions and a thickness of 0.1 mm. Growth of the crystals is carried out by a hanging drop method wherein a precipitant solution containing polyethylene glycol (PEG) and a phosphate buffer is mixed with an HSA solution, and a droplet of mixed solution is suspended over a well of precipitant solution. Crystals grow to the desired size in 3 to 7 days. Concentration of reagents, pH and other parameters are controlled within prescribed limits. The resulting crystals exhibit a size and quality such as to allow performance of x ray diffraction studies and enable the conduct of drug binding studies as well as genetic engineering studies.

Growth and characterization of KDP crystals doped with L-aspartic acid.

PubMed

Krishnamurthy, R; Rajasekaran, R; Samuel, Bincy Susan

2013-03-01

Potassium Dihydrogen Phosphate (KDP) doped with L-aspartic acid has been grown by solvent slow evaporation technique from a mixture of aqueous solution of KDP and 0.7% of L-aspartic acid at room temperature. The grown crystals were characterized by powder X-ray diffraction, UV-visible, FTIR analysis. The doping of aspartic acid was confirmed by FTIR spectrum. The Nonlinear optical property (SHG) of L-aspartic acid doped KDP has been confirmed. Microhardness studies were carried out on the grown crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

Growth and optical waveguide fabrication in spinel MgGa2O4 crystal

NASA Astrophysics Data System (ADS)

Wang, Liang-Ling; Cui, Xiao-Jun; Rensberg, Jura; Wu, Kui; Wesch, Werner; Wendler, Elke

2017-10-01

We report on optical waveguide fabrication in a spinel MgGa2O4 crystal by 6.0 MeV carbon ion implantation at a fluence of 2 × 1015 ions/cm2 for the first time to our knowledge. The MgGa2O4 crystal was grown by the floating zone method. The refractive index profile reconstructed by reflectivity calculation method showed that the MgGa2O4 waveguide is a typical barrier waveguide. The typical barrier-shaped refractive index profile is attributed mainly to the nuclear energy deposition of the incident carbon ions into the MgGa2O4 crystal. By performing end-coupling measurements and using the beam propagation method (BPM) for the analysis of the observed modes, it can be concluded that the modes can be confined inside the waveguide.

Temperature Dependence of Morphology and Growth Mechanism of Vapor-Grown Cd crystals as Affected by Bi Impurities

NASA Astrophysics Data System (ADS)

Yumoto, Hisami; Hasiguti, Ryukiti R.

1984-07-01

Hexagonal prismatic Cd crystals having {10\\bar{1}0} prismatic planes, or occasionally having {11\\bar{2}0} prismatic planes, were grown as high-temperature-type Cd crystals by the thin layer VLS mechanism at Ts (growth temperature) ≥ Tt (transition temperature range: 250-260°C). Pencil-shaped Cd crystals (low-temperature-type Cd crystals) were grown, having {10\\bar{1}0} and {11\\bar{2}0} prismatic planes and {10\\bar{1}1} pyramidal planes by the mixed-type VLS mechanism at Ts≤Tt. When the growth temperature was decreased below Tt, the shape of the solid-liquid interface changed from rounded to faceted. Three processes for the termination of the mixed-type VLS growth are proposed.

Multi-ampoule Bridgman growth of halide scintillator crystals using the self-seeding method

NASA Astrophysics Data System (ADS)

Lindsey, Adam C.; Wu, Yuntao; Zhuravleva, Mariya; Loyd, Matthew; Koschan, Merry; Melcher, Charles L.

2017-07-01

We investigate the multi-ampoule growth at 25 mm diameter of ternary iodide single crystal scintillator KCaI3:Eu using the randomly oriented self-seeded Bridgman method. We compare scintillation performance between cubic inch scale crystals containing small variations of low nominal europium concentrations previously shown to balance light yield with self-absorption in the host crystal. Growth conditions were optimized in the developmental furnace and four 2 in3 KCaI3:Eu crystals were grown simultaneously producing a total of six 25 mm × 25 mm cylinders. Small variations in activator concentration did not result in significant performance differences among the six measured crystals. A range of energy resolutions of 3.5-4.7% at 662 keV was achieved, surpassing that of NaI:Tl crystals commonly used in spectroscopic detection applications. The function and basic design of the multi-ampoule furnace as well as the process of growing single crystals of KCaI3 is included here.

Study of the growth and pyroelectric properties of TGS crystals doped with aniline-family dipolar molecules

NASA Astrophysics Data System (ADS)

Zhang, Kecong; Song, Jiancheng; Wang, Min; Fang, Changshui; Lu, Mengkai

1987-04-01

TGS crystals doped with aniline-family dipolar molecules (aniline, 2-aminobenzoic acid, 3-aminobenzoic acid, 3-aminobenzene-sulphonic acid, 4-aminobenzenesulphonic acid and 4-nitroraniline) have been grown by the slow-cooling solution method. The influence of these dopants on the growth habits, crystal morphology pyroelectric properties, and structure parameters of TGS crystals has been systematically investigated. The effects of the domain structure of the seed crystal on the pyroelectric properties of the doped crystals have been studied. It is found that the spontaneous polarization (P), pyroelectric coefficient (lambda), and internal bias field of the doped crystals are slightly higher than those of the pure TGS, and the larger the dipole moment of the dopant molecule, the higher the P and lambda of the doped TGS crystal.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Liang; Nachtergaele, Sigrid; Seddon, Annela M.

This paper utilizes cyclodextrin-based host-guest chemistry in a microfluidic device to modulate the crystallization of membrane proteins and the process of concentration of membrane protein samples. Methyl-{beta}-cyclodextrin (MBCD) can efficiently capture a wide variety of detergents commonly used for the stabilization of membrane proteins by sequestering detergent monomers. Reaction Center (RC) from Blastochloris viridis was used here as a model system. In the process of concentrating membrane protein samples, MBCD was shown to break up free detergent micelles and prevent them from being concentrated. The addition of an optimal amount of MBCD to the RC sample captured loosely bound detergentmore » from the protein-detergent complex and improved sample homogeneity, as characterized by dynamic light scattering. Using plug-based microfluidics, RC crystals were grown in the presence of MBCD, giving a different morphology and space group than crystals grown without MBCD. The crystal structure of RC crystallized in the presence of MBCD was consistent with the changes in packing and crystal contacts hypothesized for removal of loosely bound detergent. The incorporation of MBCD into a plug-based microfluidic crystallization method allows efficient use of limited membrane protein sample by reducing the amount of protein required and combining sparse matrix screening and optimization in one experiment. The use of MBCD for detergent capture can be expanded to develop cyclodextrin-derived molecules for fine-tuned detergent capture and thus modulate membrane protein crystallization in an even more controllable way.« less

Design and Growth of Novel Compounds for Radiation Sensors: Multinary Chalcogenides

NASA Technical Reports Server (NTRS)

Singh, N. B.; Su, Ching-Hua; Nagaradona, Teja; Arnold, Brad; Choa, Fow-Sen

2016-01-01

Increasing threats of radiological weapons have revitalized the researches for low cost large volume ?-ray and neutron ray sensors In the past few years we have designed and grown ternary and quaternary lead and thallium chalcogenides and lead selenoiodides for detectors to meet these challenges. These materials are congruent, can be tailored to enhance the parameters required for radiation sensors. In addition, this class of compounds can be grown by Bridgman method which promises for large volume productions. We have single crystals of several compounds from the melt including Tl3AsSe3, Tl3AsSe3-xSx, TlGaSe2, AgGaGe3Se8, AgxLi1-xAgGaGe3Se8 and PbTlI5-x Sex compounds. Experimental studies indicate that these have very low absorption coefficient, low defect density and can be fabricated in any shape and sizes. These crystals do not require post growth annealing and do not show any second phase precipitates when processed for electrode bonding and other fabrication steps. In this paper we report purification, growth and fabrication of large Tl3AsSe3 (TAS) crystals. We observed that TAS crystals grown by using further purification of as supplied high purity source materials followed by directionally solidified charge showed higher resistivity than previously reported values. TAS also showed constant value as the function of voltage. A low thermal gradient and high purity source material were used to reduce thermal stresses in large crystals. By improving the purification of the as supplied source materials very high quality thallium, selenium and arsenic was achieved for preparing stoichiometric Tl3AsSe3 compound. Low gradient (<20K/cm) and slow growth rate (1-2 cm/day) produced crystals with reduced stress. Crystals did not show any micro cracking during fabrication of crystals grown with high purity and at low thermal gradient. Since thallium is a major component and very sensitive to surface oxidation, removal of surface and bulk oxides is very important. Intentional increase in the growth rate from 1cm/day to higher speed (>5cm/day) showed very different morphologies on the surface of the crystals. Electrical resistivity was one order of magnitude higher than previously reported value and it was observed to be constant as the function of frequency.

Top-seeded solution growth and morphology change of RbTiOPO4:Ta single crystal

NASA Astrophysics Data System (ADS)

Li, Ziqing; Chen, Yang; Zhu, Pengfei; Ji, Nianjing; Duan, Xiulan; Jiang, Huaidong

2018-04-01

The RbTiOPO4:Ta single crystal with dimensions of 4 mm × 31 mm × 18 mm was successfully grown by Top Seeded Solution Growth Technique. It is concluded that the doping Ta element can strongly influence the growth and morphology of the RbTiOPO4 crystal. The evident morphology change of RbTiOPO4:Ta crystal with respect to RbTiOPO4 crystal has been observed and the (1 0 0) crystal face was more developed than any other crystal faces. The possible reasons of the morphology change were analyzed through experimental and theoretical methods. Several methods were tried to increase crystallographic a direction dimension of RbTiOPO4:Ta crystals. Finally, the RbTiOPO4:Ta single crystal with crystallographic a direction dimension up to 6 mm was obtained by using thicker seed crystal. This way makes it possible to get isometric RbTiOPO4:Ta crystals, which is beneficial for nonlinear optical applications due to larger area in x-y plane.

Crystallization and preliminary X-ray diffraction study of phosphopantetheine adenylyltransferase from M. tuberculosis crystallizing in space group P3{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timofeev, V. I., E-mail: tostars@mail.ru; Chupova, L. A.; Esipov, R. S.

Crystals of M. tuberculosis phosphopantetheine adenylyltransferase were grown in microgravity by the capillary counter-diffusion method through a gel layer. The X-ray diffraction data set suitable for the determination of the three-dimensional structure at atomic resolution was collected from one crystal at the Spring-8 synchrotron facility to 2.00-Å resolution. The crystals belong to sp. gr. P3{sub 2} and have the following unit-cell parameters: a = b = 106.47 Å, c = 71.32 Å, α = γ = 90°, β = 120°. The structure was solved by the molecular-replacement method. There are six subunits of the enzyme comprising a hexamer per asymmetricmore » unit. The hexamer is a biologically active form of phosphopantetheine adenylyltransferase from M. tuberculosis.« less

Producing desired ice faces

PubMed Central

Shultz, Mary Jane; Brumberg, Alexandra; Bisson, Patrick J.; Shultz, Ryan

2015-01-01

The ability to prepare single-crystal faces has become central to developing and testing models for chemistry at interfaces, spectacularly demonstrated by heterogeneous catalysis and nanoscience. This ability has been hampered for hexagonal ice, Ih––a fundamental hydrogen-bonded surface––due to two characteristics of ice: ice does not readily cleave along a crystal lattice plane and properties of ice grown on a substrate can differ significantly from those of neat ice. This work describes laboratory-based methods both to determine the Ih crystal lattice orientation relative to a surface and to use that orientation to prepare any desired face. The work builds on previous results attaining nearly 100% yield of high-quality, single-crystal boules. With these methods, researchers can prepare authentic, single-crystal ice surfaces for numerous studies including uptake measurements, surface reactivity, and catalytic activity of this ubiquitous, fundamental solid. PMID:26512102

Growth, structural, optical, piezoelectric and etching analysis of L-lysine p-nitrophenolate monohydrate single crystals

NASA Astrophysics Data System (ADS)

Alexandar, A.; Lakshmanan, A.; Sakthy Priya, S.; Surendran, P.; Rameshkumar, P.

2017-09-01

Nonlinear optical single crystals of L-lysine p-nitrophenolate monohydrate (LLPNP) were grown in aqueous solution by the slow evaporation solution technique (SEST). The grown crystals were subjected to powder X-ray diffraction analysis, (PXRD) and it was found that the title compound was crystallized in the orthorhombic crystal system with noncentrosymmetric space group of P212121. The vibrational frequencies of various functional groups present in the crystal were analyzed using the FTIR spectrum with a wavenumber range between 450 cm-1 and 4000 cm-1. The microhardness analysis of the sample revealed that the crystal belongs to the soft material category. Piezoelectric analysis was performed to measure the value of the piezoelectric (d33) coefficient. Blue light emission of the material was confirmed using the photoluminescence spectrum. Thermal stability of the grown crystal was analyzed using a melting point apparatus and it was found that the LLPNP is stable upto 175∘C. Etching analysis was performed at various durations, in order to identify the surface properties of the LLPNP crystal.

New CVD-based method for the growth of high-quality crystalline zinc oxide layers

NASA Astrophysics Data System (ADS)

Huber, Florian; Madel, Manfred; Reiser, Anton; Bauer, Sebastian; Thonke, Klaus

2016-07-01

High-quality zinc oxide (ZnO) layers were grown using a new chemical vapour deposition (CVD)-based low-cost growth method. The process is characterized by total simplicity, high growth rates, and cheap, less hazardous precursors. To produce elementary zinc vapour, methane (CH4) is used to reduce a ZnO powder. By re-oxidizing the zinc with pure oxygen, highly crystalline ZnO layers were grown on gallium nitride (GaN) layers and on sapphire substrates with an aluminum nitride (AlN) nucleation layer. Using simple CH4 as precursor has the big advantage of good controllability and the avoidance of highly toxic gases like nitrogen oxides. In photoluminescence (PL) measurements the samples show a strong near-band-edge emission and a sharp line width at 5 K. The good crystal quality has been confirmed in high resolution X-ray diffraction (HRXRD) measurements. This new growth method has great potential for industrial large-scale production of high-quality single crystal ZnO layers.

Point defects in CdTe xSe 1-x crystals grown from a Te-rich solution for applications in detecting radiation

DOE PAGES

Gul, R.; Roy, U. N.; Bolotnikov, A. E.; ...

2015-04-15

We investigated cadmium telluride selenide (CdTeSe) crystals, newly grown by the Traveling Heater Method (THM), for the presence and abundance of point defects. Deep Level Transient spectroscopy (I-DLTS) was used to determine the energies of the traps, their capture cross sections, and densities. The bias across the detectors was varied from (1–30) V. Four types of point defects were identified, ranging from 10 meV to 0.35 eV. Two dominant traps at energies of 0.18 eV and 0.14 eV were studied in depth. Cd vacancies are found at lower concentrations than other point defects present in the material.

Tungsten-encapsulated gadolinium nanoislands with enhanced magnetocaloric response

DOE PAGES

Logan, Jonathan M.; Rosenmann, Daniel; Sangpo, Tenzin; ...

2017-07-03

Here, we report a method for growing chemically pure, oxide-free, air-stable Gd nanoislands with enhanced magnetic properties. These nanoislands are grown by solid-state dewetting and are fully encapsulated in tungsten such that they remain stable in ambient environments. They display good crystalline properties with hexagonally close-packed crystal structure and strong preferential orientation. We show that the choice of substrate strongly affects their shape, crystal orientation, and magnetic properties. The temperature-dependent magnetic coercivity and remanence of the Gd islands can vary by as much as a factor of three depending on the substrate used. The magneto- caloric properties of Gd islandsmore » grown on a sapphire substrate exceed those of high-quality Gd thin films.« less

Design and growth of novel compounds for radiation sensors: multinary chalcogenides

NASA Astrophysics Data System (ADS)

Singh, N. B.; Su, Ching-Hua; Nagaradona, Teja; Arnold, Brad; Choa, Fow-Sen

2016-05-01

Increasing threats of radiological weapons have revitalized the researches for low cost large volume γ-ray and neutron ray sensors In the past few years we have designed and grown ternary and quaternary lead and thallium chalcogenides and lead selenoiodides for detectors to meet these challenges. These materials are congruent, can be tailored to enhance the parameters required for radiation sensors. In addition, this class of compounds can be grown by Bridgman method which promises for large volume productions. We have single crystals of several compounds from the melt including Tl3AsSe3, Tl3AsSe3-xSx, TlGaSe2, AgGaGe3Se8, AgxLi1-xAgGaGe3Se8 and PbTlI5-x Sex compounds. Experimental studies indicate that these have very low absorption coefficient, low defect density and can be fabricated in any shape and sizes. These crystals do not require post growth annealing and do not show any second phase precipitates when processed for electrode bonding and other fabrication steps. In this paper we report purification, growth and fabrication of large Tl3AsSe3 (TAS) crystals. We observed that TAS crystals grown by using further purification of as supplied high purity source materials followed by directionally solidified charge showed higher resistivity than previously reported values. TAS also showed constant value as the function of voltage.

Preferred orientations of laterally grown silicon films over amorphous substrates using the vapor–liquid–solid technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

LeBoeuf, J. L., E-mail: jerome.leboeuf@mail.mcgill.ca; Brodusch, N.; Gauvin, R.

2014-12-28

A novel method has been optimized so that adhesion layers are no longer needed to reliably deposit patterned gold structures on amorphous substrates. Using this technique allows for the fabrication of amorphous oxide templates known as micro-crucibles, which confine a vapor–liquid–solid (VLS) catalyst of nominally pure gold to a specific geometry. Within these confined templates of amorphous materials, faceted silicon crystals have been grown laterally. The novel deposition technique, which enables the nominally pure gold catalyst, involves the undercutting of an initial chromium adhesion layer. Using electron backscatter diffraction it was found that silicon nucleated in these micro-crucibles were 30%more » single crystals, 45% potentially twinned crystals and 25% polycrystals for the experimental conditions used. Single, potentially twinned, and polycrystals all had an aversion to growth with the (1 0 0) surface parallel to the amorphous substrate. Closer analysis of grain boundaries of potentially twinned and polycrystalline samples revealed that the overwhelming majority of them were of the 60° Σ3 coherent twin boundary type. The large amount of coherent twin boundaries present in the grown, two-dimensional silicon crystals suggest that lateral VLS growth occurs very close to thermodynamic equilibrium. It is suggested that free energy fluctuations during growth or cooling, and impurities were the causes for this twinning.« less

Charge transport properties in CdZnTe detectors grown by the vertical Bridgman technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auricchio, N.; Caroli, E.; Marchini, L.

2011-12-15

Presently, a great amount of effort is being devoted to the development of CdTe and CdZnTe (CZT) detectors for a large variety of applications such as medical, industrial, and space research. We present the spectroscopic properties of some CZT crystals grown by the standard vertical Bridgman method and by the boron oxide encapsulated vertical Bridgman method, which has been recently implemented at IMEM-CNR (Parma, Italy). In this technique, the crystal is grown in an open quartz crucible fully encapsulated by a thin layer of liquid boron oxide. This method prevents contact between the crystal and the crucible, thereby allowing largermore » single grains with a lower dislocation density to be obtained. Several mono-electrode detectors were realized, with each having two planar gold contacts. The samples are characterized by an active area of about 7 mm x 7 mm and thicknesses ranging from 1 to 2 mm. The charge transport properties of the detectors have been studied by mobility-lifetime ({mu} x {tau}) product measurements, carried out at the European Synchrotron Radiation Facility (Grenoble, France) in the planar transverse field configuration, where the impinging beam direction is orthogonal to the collecting electric field. We have performed several fine scans between the electrodes with a beam spot of 10 {mu}m x 10 {mu}m at various energies from 60 to 400 keV. In this work, we present the test results in terms of the ({mu} x {tau}) product of both charge carriers.« less

Growth and characterization of Na2Mo2O7 crystal scintillators for rare event searches

NASA Astrophysics Data System (ADS)

Pandey, Indra Raj; Kim, H. J.; Kim, Y. D.

2017-12-01

Disodium dimolybdate (Na2Mo2O7) crystals were grown using the Czochralski technique. The thermal characteristics of the compound were analyzed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements. The crystal structure of the grown sample was confirmed using X-ray diffraction (XRD). Luminescence properties were measured at room and low temperatures, using a light emitting diode (LED) source. Very weak luminescence was observed at room temperature; however, the luminescence intensity was enhanced at low temperatures. The crystal's transmittance spectrum was measured for estimating its optical quality and energy band gap. The grown crystal exhibited a luminescence light yield of 55% compared with CaMoO4 crystals at 10 K, when excited by a 280-nm-wavelength LED source, but does not have the drawbacks of radioactive Ca isotopes. These results suggest that at cryogenic temperatures, Na2Mo2O7 crystal scintillators are promising for the detection of dark matter and neutrinoless double beta decay of 100Mo.

Growth of NH4Cl Single Crystal from Vapor Phase in Vertical Furnace

NASA Astrophysics Data System (ADS)

Nigara, Yutaka; Yoshizawa, Masahito; Fujimura, Tadao

1983-02-01

A pure and internally stress-free single crystal of NH4Cl was grown successfully from the vapor phase. The crystal measured 1.6 cmφ× 2 cm and had the disordered CsCl structure, which was stable below 184°C. The crystal was grown in an ampoule in a vertical furnace, in which the vapor was efficiently transported both by diffusion and convection. In line with the growth mechanism of a single crystal, the temperature fluctuation (°C/min) on the growth interface was kept smaller than the product of the temperature gradient (°C/cm) and the growth rate (cm/min). The specific heat of the crystal was measured around -31°C (242 K) during cooling and heating cycles by AC calorimetry. The thermal hysteresis (0.4 K) obtained here was smaller than that (0.89 K) of an NH4Cl crystal grown from its aqueous solution with urea added as a habit modifier.

Three-dimensional crystals of ribosomes and their subunits from eu- and archaebacteria.

PubMed

Glotz, C; Müssig, J; Gewitz, H S; Makowski, I; Arad, T; Yonath, A; Wittmann, H G

1987-11-01

Ordered three-dimensional crystals of 70S ribosomes as well as of 30S and 50S ribosomal subunits from various bacteria (E. coli, Bacillus stearothermophilus, Thermus thermophilus and Halobacterium marismortui) have been grown by vapour diffusion in hanging drops using mono- and polyalcohols. A new compact crystal form of 50S subunits has been obtained, and it is suitable for crystallographic studies at medium resolution. In addition, from one crystal form large crystals could be grown in X-ray capillaries. In all cases the crystals were obtained from functionally active ribosomal particles, and the particles from dissolved crystals retained their integrity and biological activity.

Single Crystal Membranes

NASA Technical Reports Server (NTRS)

Stormont, R. W.; Morrison, A.

1974-01-01

Single crystal a- and c-axis tubes and ribbons of sodium beta-alumina and sodium magnesium beta-alumina were grown from sodium oxide rich melts. Additional experiments grew ribbon crystals containing sodium magnesium beta, beta double prime, beta triple prime, and beta quadruple prime. A high pressure crystal growth chamber, sodium oxide rich melts, and iridium for all surfaces in contact with the melt were combined with the edge-defined, film-fed growth technique to grow the single crystal beta-alumina tubes and ribbons. The crystals were characterized using metallographic and X-ray diffraction techniques, and wet chemical analysis was used to determine the sodium, magnesium, and aluminum content of the grown crystals.

Growth and surface topography of WSe{sub 2} single crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dixit, Vijay, E-mail: vijdix1@gmail.com; Vyas, Chirag; Pataniya, Pratik

2016-05-06

Tungsten Di-Selenide belongs to the family of TMDCs showing their potential applications in the fields of Optoelectronics and PEC solar cells. Here in the present investigation single crystals of WSe{sub 2} were grown by Direct Vapour Transport Technique in a dual zone furnace having temperature difference of 50 K between the two zones. These single crystals were characterized by EDAX which confirms the stiochiometry of the grown crystals. Surface topography of the crystal was studied by optical micrograph showing the left handed spirals on the surface of WSe{sub 2} crystals. Single crystalline nature of the crystals was confirmed by SAED.

Molecule diagram from earth-grown crystals

NASA Technical Reports Server (NTRS)

2004-01-01

Like many chemicals in the body, the three-dimensional structure of insulin is extremely complex. When grown on the ground, insulin crystals do not grow as large or as ordered as researchers desire--obscuring the blueprint of the insulin molecules.

The perfection and defect structure of organic hourglass inclusion K 2SO 4 crystals

NASA Astrophysics Data System (ADS)

Vetter, William M.; Totsuka, Hirono; Dudley, Michael; Kahr, Bart

2002-06-01

Hourglass inclusion crystals of K 2SO 4 were grown from aqueous solutions containing the dye acid fuchsin, and studied by synchrotron white-beam X-ray topography and reciprocal space mapping. Both self-nucleated and larger, seeded dye-included crystals were prepared, as well as comparable undoped crystals. While the dye modified the crystals' habit strongly, X-ray topographs showed it had no influence on their dislocation configurations, which were typical for solution-grown crystals. No kinematical contrast arising from the presence of the dye was observed that indicated dye-induced strain in the crystal lattice. Growth sector boundaries were visible in the dyed crystals but not in undoped crystals, implying there was a slightly higher lattice mismatch across growth sector boundaries in the dye-included crystals. Reciprocal space maps of small areas on an hourglass inclusion crystal within either a dye-included growth sector or an undoped growth sector showed single peaks with the same perfect crystal rocking curve width and no dilatation or tilt of the host lattice resulting from the dye's presence. These results showed hourglass inclusion crystals can be grown in which the presence of the dye disturbs the crystalline structure of the host salt minimally, and that hourglass inclusions have the nature of a solid solution.

Spectral and multi-wavelength continuous-wave laser properties of Yb3+:BaLaGa3O7

NASA Astrophysics Data System (ADS)

Gao, Shufang; Xu, Shan

2018-05-01

Yb3+ doped BaLaGa3O7 crystal has been successfully grown by Czochralski method. The polarized absorption spectra, the fluorescence spectra and the fluorescence decay lifetime of Yb3+:BaLaGa3O7 crystal were measured at room temperature. The spectroscopic parameters of Yb3+:BaLaGa3O7 crystal are calculated. A continuous wave output power of 1.32W was obtained with four-wavelength emission corresponding to an optical-optical slope efficiency of 55%.

Optimized Ce:LiCAF amplifier pumping configurations

NASA Astrophysics Data System (ADS)

Cadatal-Raduban, Marilou; Pham, Minh Hong; Gabayno, Jacque Lynn; Yamanoi, Kohei; Empizo, Melvin John F.; Shimizu, Toshihiko; Sarukura, Nobuhiko; Nguyen, Hung Dai; Yoshikawa, Akira; Fukuda, Tsuguo

2018-02-01

Two side-pumping schemes suitable for the development of an ultraviolet femtosecond amplifier system using a Ce3+:LiCaAlF6 crystal are reported. Firstly, a Bethune-type prismatic cell configuration that uniformly illuminates the four sides of a micro-pulling down method-grown crystal is used to amplify 290 nm, femtosecond pulses with no significant increase in pulse duration and B-integral. The second pumping scheme uses a two-side-pumped large crystal. These two side-pumping schemes can pave new possibilities for achieving high-energy ultraviolet femtosecond pulses.

Structural, thermal, optical and nonlinear optical properties of ethylenediaminium picrate single crystals

NASA Astrophysics Data System (ADS)

Indumathi, C.; T. C., Sabari Girisun; Anitha, K.; Alfred Cecil Raj, S.

2017-07-01

A new organic optical limiting material, ethylenediaminium picrate (EDAPA) was synthesized through acid base reaction and grown as single crystals by solvent evaporation method. Single crystal XRD analysis showed that EDAPA crystallizes in orthorhombic system with Cmca as space group. The formation of charge transfer complex during the reaction of ethylenediamine and picric acid was strongly evident through the recorded Fourier Transform Infra Red (FTIR), Raman and Nuclear Magnetic Resonance (NMR) spectrum. Thermal (TG-DTA and DSC) curves indicated that the material possesses high thermal stability with decomposition temperature at 243 °C. Optical (UV-Visible-NIR) analysis showed that the grown crystal was found to be transparent in the entire visible and NIR region. Z-scan studies with intense short pulse (532 nm, 5 ns, 100 μJ) excitations, revealed that EDAPA exhibited two photon absorption behaviour and the nonlinear absorption coefficient was found to be two orders of magnitude higher than some of the known optical limiter like Cu nano glasses. EDAPA exhibited a strong optical limiting action with low limiting threshold which make them a potential candidate for eye and photosensitive component protection against intense short pulse lasers.

Te-and Zn-Doped InSb Crystals Grown in Microgravity

NASA Technical Reports Server (NTRS)

Ostrogorsky, A. G.; Marin, C.; Volz, M.; Bonner, W. A.; Duffar, T.

2004-01-01

In 2002, within the SUBSA (Solidification Using a Baffle in Sealed Ampoules) investigation, seven doped InSb crystals were grown in microgravity at the International Space Station. The key goals of the SUBSA investigation are: (a) to clarify the origin of the melt convection in space laboratories; (b) to reduce melt convection to the level which allows reproducible diffusion-controlled segregation; (e) to explore the submerged baffle process and liquid encapsulation in microgravity. 30 crystal growth experiments were conducted in the ground unit, to optimize the design of flight ampoules and to test the transparent SUBSA furnace developed by TecMasters Inc. The specially designed furnace, allowed observation of the crystal growth process (melting, seeding, motion of the solid-liquid interface, etc.). In the summer of 2002, eight crystal growth experiments were conducted in the Microgravity Science Glovebox (MSG) facility at the ISS. Four Te-doped (k = 0.5) and three Zn-doped (k2.9) crystals were grown on undoped seeds. In one experiment, we were not able to seed and grow. The seven grown crystals were sectioned and analyzed using SIMS. The design of the SUBSA ampoules, the segregation data and the video images obtained during the SUBSA flight experiments will be presented and discussed.

Hydrothermal Growth of Vertically Aligned ZnO Nanorods Using a Biocomposite Seed Layer of ZnO Nanoparticles.

PubMed

Ibupoto, Zafar Hussain; Khun, Kimleang; Eriksson, Martin; AlSalhi, Mohammad; Atif, Muhammad; Ansari, Anees; Willander, Magnus

2013-08-19

Well aligned ZnO nanorods have been prepared by a low temperature aqueous chemical growth method, using a biocomposite seed layer of ZnO nanoparticles prepared in starch and cellulose bio polymers. The effect of different concentrations of biocomposite seed layer on the alignment of ZnO nanorods has been investigated. ZnO nanorods grown on a gold-coated glass substrate have been characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. These techniques have shown that the ZnO nanorods are well aligned and perpendicular to the substrate, and grown with a high density and uniformity on the substrate. Moreover, ZnO nanorods can be grown with an orientation along the c -axis of the substrate and exhibit a wurtzite crystal structure with a dominant (002) peak in an XRD spectrum and possessed a high crystal quality. A photoluminescence (PL) spectroscopy study of the ZnO nanorods has revealed a conventional near band edge ultraviolet emission, along with emission in the visible part of the electromagnetic spectrum due to defect emission. This study provides an alternative method for the fabrication of well aligned ZnO nanorods. This method can be helpful in improving the performance of devices where alignment plays a significant role.

Hydrothermal Growth of Vertically Aligned ZnO Nanorods Using a Biocomposite Seed Layer of ZnO Nanoparticles

PubMed Central

Ibupoto, Zafar Hussain; Khun, Kimleang; Eriksson, Martin; AlSalhi, Mohammad; Atif, Muhammad; Ansari, Anees; Willander, Magnus

2013-01-01

Well aligned ZnO nanorods have been prepared by a low temperature aqueous chemical growth method, using a biocomposite seed layer of ZnO nanoparticles prepared in starch and cellulose bio polymers. The effect of different concentrations of biocomposite seed layer on the alignment of ZnO nanorods has been investigated. ZnO nanorods grown on a gold-coated glass substrate have been characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. These techniques have shown that the ZnO nanorods are well aligned and perpendicular to the substrate, and grown with a high density and uniformity on the substrate. Moreover, ZnO nanorods can be grown with an orientation along the c-axis of the substrate and exhibit a wurtzite crystal structure with a dominant (002) peak in an XRD spectrum and possessed a high crystal quality. A photoluminescence (PL) spectroscopy study of the ZnO nanorods has revealed a conventional near band edge ultraviolet emission, along with emission in the visible part of the electromagnetic spectrum due to defect emission. This study provides an alternative method for the fabrication of well aligned ZnO nanorods. This method can be helpful in improving the performance of devices where alignment plays a significant role. PMID:28811454

Characterization of the scintillation anisotropy in crystalline stilbene scintillator detectors

DOE PAGES

Schuster, P.; Brubaker, E.

2016-11-23

This study reports a series of measurements that characterize the directional dependence of the scintillation response of crystalline melt-grown and solution-grown trans-stilbene to incident DT and DD neutrons. These measurements give the amplitude and pulse shape dependence on the proton recoil direction over one hemisphere of the crystal, confirming and extending previous results in the literature for melt-grown stilbene and providing the first measurements for solution-grown stilbene. In similar measurements of liquid and plastic detectors, no directional dependence was observed, confirming the hypothesis that the anisotropy in stilbene and other organic crystal scintillators is a result of internal effects duemore » to the molecular or crystal structure and not an external effect on the measurement system.« less

Solution-Grown Rubrene Crystals as Radiation Detecting Devices

DOE PAGES

Carman, Leslie; Martinez, H. Paul; Voss, Lars; ...

2017-01-11

There has been increased interest in organic semiconductors over the last decade because of their unique properties. Of these, 5, 6, 11, 12-tetraphenylnaphthacene (rubrene) has generated the most interest because of its high charge carrier mobility. In this paper, large single crystals with a volume of ~1 cm 3 were grown from solution by a temperature reduction technique. The faceted crystals had flat surfaces and cm-scale, visually defect-free areas suitable for physical characterization. X-ray diffraction analysis indicates that solvent does not incorporate into the crystals and photoluminescence spectra are consistent with pristine, high-crystallinity rubrene. Furthermore, the response curve to pulsedmore » optical illumination indicates that the solution grown crystals are of similar quality to those grown by physical vapor transport, albeit larger. The good quality of these crystals in combination with the improvement of electrical contacts by application of conductive polymer on the graphite electrodes have led to the clear observation of alpha particles with these rubrene detectors. Finally, preliminary results with a 252Cf source generate a small signal with the rubrene detector and may demonstrate that rubrene can also be used for detecting high-energy neutrons.« less

Crystal growth, structural, optical, spectral and thermal studies of tris(L-phenylalanine)L-phenylalaninium nitrate: a new organic nonlinear optical material.

PubMed

Prakash, M; Geetha, D; Lydia Caroline, M

2011-10-15

Tris(L-phenylalanine)L-phenylalaninium nitrate, C(9)H(12)NO(2)(+)·NO(3)(-)·3C(9)H(11)NO(2) (TPLPN), a new organic nonlinear optical material was grown from aqueous solution by slow evaporation solution growth at room temperature. The grown crystals were subjected to powder X-ray diffraction and single crystal X-ray diffraction studies to confirm the crystalline nature and crystal structure. The modes of vibration of different molecular groups present in TPLPN have been identified by FTIR spectral analysis. The presence of hydrogen and carbon in the grown crystal were confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. The optical transmission spectral study establishes good transmitting ability of the crystal in the entire visible region. The thermogravimetric (TG) and differential thermal analyses (DTA) were carried out to understand the thermal stability of the sample. The nonlinear optical property of the compound observed using Kurtz powder second harmonic generation test assets the suitability of the grown material for the frequency conversion of laser radiation of Nd:YAG. Copyright © 2011 Elsevier B.V. All rights reserved.

Synthesis, growth, structural and optical studies of a novel organic Piperazine (bis) p-toluenesulfonate single crystal.

PubMed

Rekha, P; Peramaiyan, G; NizamMohideen, M; Kumar, R Mohan; Kanagadurai, R

2015-03-15

A novel organic single crystal of Piperazinium (bis) p-toluenesulfonate (PPTS) was grown by a slow evaporation solution growth technique. The structure of the grown crystal was determined using single crystal X-ray diffraction analysis. The PPTS crystal belongs to the triclinic crystal system with space group of P1¯. The presence of functional groups was confirmed by FTIR spectral analysis. The optical transmittance range and cut-off wavelength were identified by UV-vis-NIR spectral studies. The luminescent properties of PPTS crystal were investigated. The thermal behavior of PPTS crystal was studied by TG-DT analyses. Copyright © 2014 Elsevier B.V. All rights reserved.

Crystal growth, piezoelectric, non-linear optical and mechanical properties of lithium hydrogen oxalate monohydrate single crystal

NASA Astrophysics Data System (ADS)

Chandran, Senthilkumar; Paulraj, Rajesh; Ramasamy, P.

2017-05-01

Semi-organic lithium hydrogen oxalate monohydrate non-linear optical single crystals have been grown by slow evaporation solution growth technique at 35 °C. Single crystal X-ray diffraction study showed that the grown crystal belongs to the triclinic system with space group P1. The mechanical strength decreases with increasing load. The piezoelectric coefficient is found to be 1.41 pC/N. The nonlinear optical property was measured using Kurtz Perry powder technique and SHG efficiency was almost equal to that of KDP.

Solution-grown organic single-crystalline p-n junctions with ambipolar charge transport.

PubMed

Fan, Congcheng; Zoombelt, Arjan P; Jiang, Hao; Fu, Weifei; Wu, Jiake; Yuan, Wentao; Wang, Yong; Li, Hanying; Chen, Hongzheng; Bao, Zhenan

2013-10-25

Organic single-crystalline p-n junctions are grown from mixed solutions. First, C60 crystals (n-type) form and, subsequently, C8-BTBT crystals (p-type) nucleate heterogeneously on the C60 crystals. Both crystals continue to grow simultaneously into single-crystalline p-n junctions that exhibit ambipolar charge transport characteristics. This work provides a platform to study organic single-crystalline p-n junctions. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New supramolecular cocrystal of 2-amino-5-chloropyridine with 3-methylbenzoic acids: Syntheses, structural characterization, Hirshfeld surfaces and quantum chemical investigations

NASA Astrophysics Data System (ADS)

Thanigaimani, Kaliyaperumal; Khalib, Nuridayanti Che; Temel, Ersin; Arshad, Suhana; Razak, Ibrahim Abdul

2015-11-01

2-amino-5-chloropyridine: 3-methylbenzoic acid [(2A5CP) (3MBA)] (I) cocrystal was synthesized and its single crystal was grown by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal X-ray diffraction technique. The cocrystal belongs to the monoclinic crystallographic system with space group P21/c, Z = 4, and a = 13.3155 (5) Å, b = 5.5980 (2) Å, c = 18.3787 (7) Å, β = 110.045 (2)°. The crystal structure is stabilized by Npyridine-H•••Odbnd C, Cdbnd O-H•••Npyridine and C-H⋯O type hydrogen bonding interactions. The presence of unionized -COOH functional group in the cocrystal was identified both by spectral methods and X-ray structural analysis. The experimental studies obtained by using the methods of single crystal X-ray analysis, powder X-ray diffraction (PXRD) analysis, FTIR, 1H NMR and 13C NMR spectroscopies confirmed the predicted cocrystal. The supramolecular assembly of the cocrystal was analyzed and discussed. The molecular geometry, vibrational frequencies of the compound in the ground state were calculated by using the density functional theory (DFT) method with 6-311++G (d,p) basis set and were compared with the experimental data. Additionally, HOMO-LUMO energy gap, natural bond orbital (NBO) analysis and nonlinear optical (NLO) properties of the compound were performed at B3LYP/6-311++G (d,p) level. Hirshfeld surfaces were used to confirm the existence of inter-molecular interactions in the compound.

First Protein Crystallization Experiments on The International Space Station: Sweet Success in Space With Thaumatin

NASA Technical Reports Server (NTRS)

Kundrot, Craig E.; Barnes, Cindy L.; Snell, Eddie H.; Achari, Aniruddha; Whitaker, Ann F. (Technical Monitor)

2001-01-01

We determined the room temperature 1.2 A structure of thaumatin using a crystal grown in the first protein crystallization experiment conducted aboard the International Space Station (ISS). The crystals were grown in the Enhanced Gaseous Nitrogen Dewar (EGN) developed by Alexander McPherson and co-workers. EGN transports frozen solutions contained in tygon tubing in a liquid nitrogen Dewar to ISS where the tubes then thaw. Batch, free interface diffusion (FID), or vapor diffusion crystallization occurs after thawing. EGN was flown to the ISS on STS-106 on September 8, 2000. This was a "risk mitigation" flight that tested EGN performance and the process of conducting experiments on ISS. We focused on how to map a hanging drop crystallization recipe to the EGN FID method. Thaumatin was chosen as the test system. Three series of crystallization recipes were set-up. Each series tested different volume ratios of protein-rich solution to precipitant-rich solution. The series differed from each other by fixing either the protein concentration or the amount of protein in the solutions. Upon return of the samples to Earth on October 24 by STS-92, bubbles that spanned the diameter of the tubing were observed in all tubes. Such bubbles interrupt liquid-liquid diffusion and force vapor diffusion equilibration to occur instead. Nonetheless, crystals grew in 9 of 30 tubes. Many large crystals were grown, the largest being 2.0 x 1.1 x 1.0 cubic mm. The largest crystal was used to collect data at room temperature on beamline 7-1 of the Stanford Synchrotron Radiation Source to a maximum resolution of 1.2 A. The structure was refined anisotropically using SHELX with a data to parameter ratio of 4.5 to give an R(sub factor) of 15.8% (R(sub free) = 18.2%) for ail reflections without generated hydrogens. This refinement is proceeding. Comparisons of this 1.2 A microgravity structure to previous reports of the thaumatin structure at 1.75 A and to ground control crystals will be presented.

Growth and characterization of novel organic 3-Hydroxy Benzaldehyde-N-methyl 4 Stilbazolium Tosylate crystals for NLO applications.

PubMed

Jagannathan, K; Umarani, P; Ratchagar, V; Ramesh, V; Kalainathan, S

2016-01-15

The 3-Hydroxy Benzaldehyde-N-methyl 4-Stilbazolium Tosylate (3- HBST) is a new organic NLO crystal and it is a new derivative in stilbazolium tosylate family. In this work we have synthesized 3-HBST and the single crystal was grown by conventional slow cooling method. The structure and lattice parameters of the grown crystal were determined by the single crystal X-ray diffraction (XRD) technique and it is exhibiting good crystalline nature which is observed from the powder XRD. In order to check the crystalline quality the rocking curve was recorded using multi crystal X-ray diffractometer. The functional groups were identified from both FTIR and NMR spectral analyses. The π-π* and n-π* optical transition energy levels were estimated from the absorption peaks. The NLO property was confirmed by measuring relative SHG efficiency by Kurtz powder test; it shows 24 times higher SHG efficiency than that of urea. In order to test the mechanical stability the Vickers and Knoop micro hardness measurement were carried out and found that the micro hardness number decreases with increasing load. The melting point was determined from Differential Scanning Colorimetry (DSC). Copyright © 2015 Elsevier B.V. All rights reserved.

Basic ammonothermal GaN growth in molybdenum capsules

NASA Astrophysics Data System (ADS)

Pimputkar, S.; Speck, J. S.; Nakamura, S.

2016-12-01

Single crystal, bulk gallium nitride (GaN) crystals were grown using the basic ammonothermal method in a high purity growth environment created using a non-hermetically sealed molybdenum (Mo) capsule and compared to growths performed in a similarly designed silver (Ag) capsule and capsule-free René 41 autoclave. Secondary ion mass spectrometry (SIMS) analysis revealed transition metal free (<1×1017 cm-3) GaN crystals. Anomalously low oxygen concentrations ((2-6)×1018 cm-3) were measured in a {0001} seeded crystal boule grown using a Mo capsule, despite higher source material oxygen concentrations ((1-5)×1019 cm-3) suggesting that molybdenum (or molybdenum nitrides) may act to getter oxygen under certain conditions. Total system pressure profiles from growth runs in a Mo capsule system were comparable to those without a capsule, with pressures peaking within 2 days and slowly decaying due to hydrogen diffusional losses. Measured Mo capsule GaN growth rates were comparable to un-optimized growth rates in capsule-free systems and appreciably slower than in Ag-capsule systems. Crystal quality replicated that of the GaN seed crystals for all capsule conditions, with high quality growth occurring on the (0001) Ga-face. Optical absorption and impurity concentration characterization suggests reduced concentrations of hydrogenated gallium vacancies (VGa-Hx).

Orientation of liquid crystalline blue phases on unidirectionally orienting surfaces

NASA Astrophysics Data System (ADS)

Takahashi, Misaki; Ohkawa, Takuma; Yoshida, Hiroyuki; Fukuda, Jun-ichi; Kikuchi, Hirostugu; Ozaki, Masanori

2018-03-01

Liquid crystalline cholesteric blue phases (BPs) continue to attract interest due to their fast response times and quasi-polarization-independent phase modulation capabilities. Various approaches have recently been proposed to control the crystal orientation of BPs on substrates; however, their basic orientation properties on standard, unidirectionally orienting alignment layers have not been investigated in detail. Through analysis of the azimuthal orientation of Kossel diagrams, we study the 3D crystal orientation of a BP material—with a phase sequence of cholesteric, BP I, and BP II—on unidirectionally orienting surfaces prepared using two methods: rubbing and photoalignment. BP II grown from the isotropic phase is sensitive to surface conditions, with different crystal planes orienting on the two substrates. On the other hand, strong thermal hysteresis is observed in BPs grown through a different liquid crystal phase, implying that the preceding structure determines the orientation. More specifically, the BP II-I transition is accompanied by a rotation of the crystal such that the crystal direction defined by certain low-value Miller indices transform into different directions, and within the allowed rotations, different azimuthal configurations are obtained in the same cell depending on the thermal process. Our findings demonstrate that, for the alignment control of BPs, the thermal process is as important as the properties of the alignment layer.

Electron-hole diffusion lengths >175 μm in solution-grown CH 3NH 3PbI 3 single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Qingfeng; Fang, Yanjun; Shao, Yuchuan

Long, balanced electron and hole diffusion lengths greater than 100 nanometers in the polycrystalline organolead trihalide compound CH 3NH 3PbI 3 are critical for highly efficient perovskite solar cells. We found that the diffusion lengths in CH 3NH 3PbI 3 single crystals grown by a solution-growth method can exceed 175 micrometers under 1 sun (100 mW cm –2) illumination and exceed 3 millimeters under weak light for both electrons and holes. The internal quantum efficiencies approach 100% in 3-millimeter-thick single-crystal perovskite solar cells under weak light. These long diffusion lengths result from greater carrier mobility, longer lifetime, and much smallermore » trap densities in the single crystals than in polycrystalline thin films. As a result, the long carrier diffusion lengths enabled the use of CH 3NH 3PbI 3 in radiation sensing and energy harvesting through the gammavoltaic effect, with an efficiency of 3.9% measured with an intense cesium-137 source.« less

Crystal growth and scintillation properties of Nd-doped Lu 3Al 5O 12 single crystals with different Nd concentrations

NASA Astrophysics Data System (ADS)

Sugiyama, Makoto; Fujimoto, Yutaka; Yanagida, Takayuki; Yokota, Yuui; Pejchal, Jan; Furuya, Yuki; Tanaka, Hidehiko; Yoshikawa, Akira

2011-04-01

Nd 0.1%, 0.5%, 1% and 3% doped Lu 3Al 5O 12 (Nd:LuAG) single crystals were grown in the nitrogen atmosphere by the micro-pulling down (μ-PD) method. The grown crystals had a single-phase confirmed by powder XRD analysis. In absorption spectra, some weak absorption lines due to Nd 3+ 4f-4f transitions were observed and their intensity increased with the increase of Nd concentration. When excited by 241Am α-ray, a broad emission peak due to defects in the host lattice at 320 nm and some sharp lines due to Nd 3+ 4f-4f transitions at wavelength longer than 400 nm were observed. The decay time profiles of Nd:LuAG under γ-ray excitation were well approximated by two exponential function of 340-760 ns and 3-5 μs for each sample. By pulse height measurement using 137Cs, Nd 0.5%:LuAG showed the highest light yield of 7600 ± 760 photons/MeV.

Crystal growth, electronic structure and optical properties of Sr2Mg(BO3)2

NASA Astrophysics Data System (ADS)

Lv, Xianshun; Wei, Lei; Wang, Xuping; Xu, Jianhua; Yu, Huajian; Hu, Yanyan; Zhang, Huadi; Zhang, Cong; Wang, Jiyang; Li, Qinggang

2018-02-01

Single crystals of Sr2Mg(BO3)2 (SMBO) were grown by Kyropoulos method. X-ray powder diffraction (XRD) analysis, transmission spectrum, thermal properties, band structure, density of states and charge distribution as well as Raman spectra of SMBO were described. The as-grown SMBO crystals show wide transparency range with UV cut-off below 180 nm. A direct band gap of 4.66 eV was obtained from the calculated electronic structure results. The calculated band structure and density of states results indicated the top valence band is determined by O 2p states whereas the low conduction band mainly consists of Sr 5s states. Twelve Raman peaks were observed in the experimental spectrum, fewer than the number predicted by the site group analysis. Raman peaks of SMBO were assigned combining first-principle calculation and site group analysis results. The strongest peak at 917 cm-1 in the experimental spectrum is assigned to symmetric stretching mode A1‧(ν1) of free BO3 units. SMBO is a potential Raman crystal which can be used in deep UV laser frequency conversion.

Electron-hole diffusion lengths >175 μm in solution-grown CH 3NH 3PbI 3 single crystals

DOE PAGES

Dong, Qingfeng; Fang, Yanjun; Shao, Yuchuan; ...

2015-02-27

Long, balanced electron and hole diffusion lengths greater than 100 nanometers in the polycrystalline organolead trihalide compound CH 3NH 3PbI 3 are critical for highly efficient perovskite solar cells. We found that the diffusion lengths in CH 3NH 3PbI 3 single crystals grown by a solution-growth method can exceed 175 micrometers under 1 sun (100 mW cm –2) illumination and exceed 3 millimeters under weak light for both electrons and holes. The internal quantum efficiencies approach 100% in 3-millimeter-thick single-crystal perovskite solar cells under weak light. These long diffusion lengths result from greater carrier mobility, longer lifetime, and much smallermore » trap densities in the single crystals than in polycrystalline thin films. As a result, the long carrier diffusion lengths enabled the use of CH 3NH 3PbI 3 in radiation sensing and energy harvesting through the gammavoltaic effect, with an efficiency of 3.9% measured with an intense cesium-137 source.« less

Structure and optical properties of 2D layered MoS2 crystals implemented with novel friction induced crystal growth

NASA Astrophysics Data System (ADS)

Tanabe, Tadao; Ito, Takafumi; Oyama, Yutaka

2018-03-01

We used X-ray diffraction, and Raman and photoluminescence (PL) spectroscopies to examine the structure and optical properties of molybdenum disulfide (MoS2) crystals grown by friction at the interface between two materials. MoS2 is produced chemically from molybdenum dithiocarbamates (MoDTC) in synthetic oil under sliding friction conditions. The X-ray diffraction (XRD) patterns indicate that the structure of the MoS2 is layered with the c-axis perpendicular to the surface. The MoS2 layer was formed on stainless steel and germanium by friction at the interface between these materials and high carbon chromium bearing steel. The number of layers is estimated to be N (N > 6) from the distance between the Raman frequencies of the E12g and A1g modes. For MoS2 grown on stainless steel, exciton peak is observed in the PL spectrum at room temperature. These results show that this friction induced crystal growth method is viable for synthesizing atomic layers of MoS2 at solid surfaces.

Synthesis, structural, optical and thermal studies of an organic nonlinear optical 4-aminopyridinium maleate single crystal.

PubMed

Pandi, P; Peramaiyan, G; Kumar, M Krishna; Kumar, R Mohan; Jayavel, R

2012-03-01

Synthesis and growth of a novel organic nonlinear optical (NLO) crystal of 4-aminopyridinium maleate (4APM) in larger size by the slow evaporation solution growth technique are reported. Single crystal and powder X-ray diffraction analyses reveal that 4APM crystallizes in monoclinic system with space group P2(1) with cell parameters a=8.140(4)Å, b=5.457(5)Å, c=10.926(10)Å and volume=481.4(7)Å(3). The grown crystal has been characterized by Fourier transform infrared and UV-visible spectral analyses. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) have been carried out to study its thermal properties. Dielectric measurements have been carried out to study the distribution of charges within the crystal. The mechanical strength of the crystal has been studied by using Vickers' microhardness test. The etching studies have been carried out on the grown crystal. The Kurtz and Perry powder SHG technique confirms the NLO property of the grown crystal and the SHG efficiency of 4APM was found to be 4.8 times greater than that of KDP crystal. Copyright © 2011 Elsevier B.V. All rights reserved.

Infrared and Raman spectroscopy and DFT calculations of DL amino acids: Valine and lysine hydrochloride

NASA Astrophysics Data System (ADS)

Paiva, F. M.; Batista, J. C.; Rêgo, F. S. C.; Lima, J. A.; Freire, P. T. C.; Melo, F. E. A.; Mendes Filho, J.; de Menezes, A. S.; Nogueira, C. E. S.

2017-01-01

Single crystals of DL-valine and DL-lysine hydrochloride were grown by slow evaporation method and the crystallographic structure were confirmed by X-ray diffraction experiment and Rietveld method. These two crystals have been studied by Raman spectroscopy in the 25-3600 cm-1 spectral range and by infrared spectroscopy through the interval 375-4000 cm-1 at room temperature. Experimental and theoretical vibrational spectra were compared and a complete analysis of the modes was done in terms of the Potential Energy Distribution (PED).

Concentration and structure inhomogeneities in GaSb(Si) single crystals grown at different heat and mass transfer conditions

NASA Astrophysics Data System (ADS)

Serebryakov, Yu. A.; Prokhorov, I. A.; Vlasov, V. N.; Korobeynikova, E. N.; Zakharov, B. G.; Shul'pina, I. L.; Marchenko, M. P.; Fryazinov, I. V.

2007-06-01

Results of ground-based experiments on crystallization of gallium antimonide on the POLIZON facility carried out within the framework of space experiment preparation aboard FOTON satellite are submitted. Technical and technological opportunities of suppression of disturbing factors for improvement of quality of grown crystals in space are substantiated. Features of formation of concentration and structure inhomogeneities in GaSb:Si crystals grown under non-stationary and stationary convection conditions are investigated. Experimental data about structure and dopant distribution inhomogeneities are discussed taking into account results of numerical researches of GaSb:Si crystallization. Also earlier received results of modeling of GaSb:Te crystallization under close temperature conditions are used. Correlation between computational and experimental data is shown. The data on intensity of flows close to crystallization front are received at which non-stationary or stationary conditions of crystallization are realized. The forecast for space conditions is made. The influence of a rotating magnetic field on convection in melt for application in space experiment projected is investigated.

Growth and physicochemical properties of second-order nonlinear optical 2-amino-5-chloropyridinium trichloroacetate single crystals

NASA Astrophysics Data System (ADS)

Renugadevi, R.; Kesavasamy, R.

2015-09-01

The growth of organic nonlinear optical (NLO) crystal 2-amino-5-chloropyridinium trichloroacetate (2A5CPTCA) has been synthesized and single crystals have been grown from methanol solvent by slow evaporation technique. The grown crystals were subjected to various characterization analyses in order to find out the suitability for device fabrication. Single crystal X-ray diffraction analysis reveals that 2A5CPTCA crystallizes in monoclinic system with the space group Cc. The grown crystal was further characterized by Fourier transform infrared spectral analysis to find out the functional groups. The nuclear magnetic resonance spectroscopy is a research technique that exploits the magnetic properties of certain atomic nuclei. The optical transparency window in the visible and near-IR (200--1100 nm) regions was found to be good for NLO applications. Thermogravimetric analysis and differential thermal analysis were used to study its thermal properties. The powder second harmonic generation efficiency measurement with Nd:YAG laser (1064 nm) radiation shows that the highest value when compared with the standard potassium dihydrogen phosphate crystal.

Origin of green luminescence in hydrothermally grown ZnO single crystals

NASA Astrophysics Data System (ADS)

Čížek, J.; Valenta, J.; Hruška, P.; Melikhova, O.; Procházka, I.; Novotný, M.; Bulíř, J.

2015-06-01

Combining photoluminescence and positron annihilation studies of hydrothermally grown ZnO crystals with stoichiometry varied by controlled annealing enabled us to clarify the origin of green luminescence. It was found that green luminescence in ZnO has multiple origins and consists of a band at 2.3(1) eV due to recombination of electrons of the conduction band by zinc vacancy acceptors coupled with hydrogen and a band at 2.47(2) eV related to oxygen vacancies. The as-grown ZnO crystals contain zinc vacancies associated with hydrogen and exhibit a green luminescence at 2.3(1) eV. Annealing in Zn vapor removed zinc vacancies and introduced oxygen vacancies. This led to disappearance of the green luminescence band at 2.3(1) eV and appearance of a green emission at higher energy of 2.47(2) eV. Moreover, the color of the crystal was changed from colorless to dark red. In contrast, annealing of the as-grown crystal in Cd vapor did not remove zinc vacancies and did not cause any significant change of green luminescence nor change in coloration.

A Program of Research on Microfabrication Techniques for VLSI Magnetic Devices.

DTIC Science & Technology

1982-10-01

contribution to the implantation- induced uniaxial anisotropy field change. BACKGROUND Magnetic garnet films are grown by liquid phase epitaxy ( LPE ) on non...a single crystal, non-magnetic garnet substrate by the liquid phase epitaxy ( LPE ) method. These thin films , usually one to three microns in thickness...microscopy. Experimental Procedures Films of (SmYGdTm)3Ca0a.Fe4.6012 garnet were grown by liquid phase epitaxy ( LPE ) on gadolinium-gallium garnet (GGG

Growth, spectral and optical characterization of a novel nonlinear optical organic material: D-Alanine DL-Mandelic acid single crystal

NASA Astrophysics Data System (ADS)

Jayaprakash, P.; Mohamed, M. Peer; Caroline, M. Lydia

2017-04-01

An organic nonlinear optical single crystal, D-alanine DL-mandelic acid was synthesized and successfully grown by slow evaporation solution growth technique at ambient temperature using solvent of aqueous solution. The unit cell parameters were assessed from single crystal X-ray diffraction analysis. The presence of diverse functional groups and vibrational modes were identified using Fourier Transform Infra Red and Fourier Transform Raman spectral analyses. The chemical structure of grown crystal has been identified by Nuclear Magnetic Resonance spectroscopic study. Ultraviolet-visible spectral analysis reveal that the crystal has lower cut-off wavelength down to 259 nm, is a key factor to exhibit second harmonic generation signal. The electronic optical band gap and Urbach energy is calculated as 5.31 eV and 0.2425 eV respectively from the UV absorption profile. The diverse optical properties such as, extinction coefficient, reflectance, linear refractive index, optical conductivity was calculated using UV-visible data. The relative second harmonic efficiency of the compound is found to be 0.81 times greater than that of KH2PO4 (KDP). The thermal stability of the grown crystal was studied by thermogravimetric analysis and differential thermal analysis techniques. The luminescence spectrum exhibited two peaks (520 nm, 564 nm) due to the donation of protons from carboxylic acid to amino group. The Vickers microhardness test was carried out employing one of the as-grown hard crystal and there by hardness number (Hv), Meyer's index (n), yield strength (σy), elastic stiffness constant (C11) and Knoop hardness number (HK) were assessed. The dielectric behaviour of the as-grown crystal was analyzed for different temperatures (313 K, 333 K, 353 K, and 373 K) at different frequencies.

Crystallization of proteins by dynamic control of supersaturation. Ph.D. Thesis Semiannual Status Report, 21 Mar. - 20 Sep. 1990

NASA Technical Reports Server (NTRS)

Wilson, Lori June

1990-01-01

The growth of protein crystals is known to be the limiting factor in the determination of the three-dimensional structures of most proteins. It is expected that the kinetics of supersaturation, which is directly related to solvent evaporation, will affect protein crystal growth and nucleation and accordingly determine the quality, number, size, and morphology of the crystals. With a technique that controls the evaporation of solvent from a protein solution with N2(g) it is possible to determine the effect of different evaporation profiles on hen egg white lysozyme crystals. Hen egg white lysozyme was chosen as the model protein because it crystallizes easily and has solubility data available for most salt, pH, and temperature ranges. Commercially available lysozyme was further purified by a number of methods. Crystals grown with the purified lysozyme and with the unpurified lysozyme in citrate buffer were different shapes but were found to be of the same symmetry space group by precession photos. Differences were seen in the lysozyme crystals grown using different evaporation rates. At three of the four initial conditions for lysozyme crystal growth, longer evaporation times yielded better crystals. The evaporation times required to see a change in the appearance of the crystals was much longer than expected. The number of rates studied so far represent only a small fraction of the ones now available with the gas evaporation device. The technique also provides for control of both solution pH and temperature which are related to the solubilities of proteins.

X-ray probe of GaN thin films grown on InGaN compliant substrates

NASA Astrophysics Data System (ADS)

Xu, Xiaoqing; Li, Yang; Liu, Jianming; Wei, Hongyuan; Liu, Xianglin; Yang, Shaoyan; Wang, Zhanguo; Wang, Huanhua

2013-04-01

GaN thin films grown on InGaN compliant substrates were characterized by several X-ray technologies: X-ray reciprocal space mapping (RSM), grazing incidence X-ray diffraction (GIXRD), and X-ray photoemission spectrum (XPS). Narrow Lorentz broadening and stress free state were observed for GaN grown on InGaN compliant substrate, while mosaic structure and large tensile stress were observed at the presence of residual indium atoms. RSM disclosed the mosaicity, and the GIXRD was conducted to investigate the depth dependences of crystal quality and strain states. XPS depth profile of indium contents indicated that residual indium atoms deteriorated the crystal quality of GaN not only by producing lattice mismatch at the interface of InGaN and GaN but also by diffusing into GaN overlayers. Accordingly, two solutions were proposed to improve the efficiency of self-patterned lateral epitaxial overgrowth method. This research goes a further step in resolving the urgent substrate problem in GaN fabrication.

Evaluation of the increase in threading dislocation during the initial stage of physical vapor transport growth of 4H-SiC

NASA Astrophysics Data System (ADS)

Suo, Hiromasa; Tsukimoto, Susumu; Eto, Kazuma; Osawa, Hiroshi; Kato, Tomohisa; Okumura, Hajime

2018-06-01

The increase in threading dislocation during the initial stage of physical vapor transport growth of n-type 4H-SiC crystals was evaluated by cross-sectional X-ray topography. Crystals were grown under two different temperature conditions. A significant increase in threading dislocation was observed in crystals grown at a high, not low, temperature. The local strain distribution in the vicinity of the grown/seed crystal interface was evaluated using the electron backscatter diffraction technique. The local nitrogen concentration distribution was also evaluated by time-of-flight secondary ion mass spectrometry. We discuss the relationship between the increase in threading dislocation and the local strain due to thermal stress and nitrogen concentration.

Highly resistive C-doped hydride vapor phase epitaxy-GaN grown on ammonothermally crystallized GaN seeds

NASA Astrophysics Data System (ADS)

Iwinska, Malgorzata; Piotrzkowski, Ryszard; Litwin-Staszewska, Elzbieta; Sochacki, Tomasz; Amilusik, Mikolaj; Fijalkowski, Michal; Lucznik, Boleslaw; Bockowski, Michal

2017-01-01

GaN crystals were grown by hydride vapor phase epitaxy (HVPE) and doped with C. The seeds were high-structural-quality ammonothermally crystallized GaN. The grown crystals were highly resistive at 296 K and of high structural quality. High-temperature Hall effect measurements revealed p-type conductivity and a deep acceptor level in the material with an activation energy of 1 eV. This is in good agreement with density functional theory calculations based on hybrid functionals as presented by the Van de Walle group. They obtained an ionization energy of 0.9 eV when C was substituted for N in GaN and acted as a deep acceptor.

Scintillation properties of Li6Y0.5Gd0.5(BO3)3: Ce3+ single crystal

NASA Astrophysics Data System (ADS)

Fawad, U.; Rooh, Gul; Kim, H. J.; Park, H.; Kim, Sunghwan; Khan, Sajid

2015-01-01

The Ce3+ doped mixed crystals of Li6Y(BO3)3 and Li6Gd(BO3)3 are grown by Czochralski technique with equal mole ratios of both Yttrium and Gadolinium i.e. Li6Y0.5Gd0.5(BO3)3. The grown crystals have the dimensions of ∅10×30 mm2. Powder X-ray diffraction (XRD) analysis confirmed single phase of the grown crystals. X-ray and laser induced luminescence spectra are presented. Scintillation properties such as energy resolution, light yield, decay time and α/β ratio under the excitation of 137Cs γ-ray photons and 241Am α-particles are also reported in this article.

Thermal, spectroscopic properties and laser performance at 1.06 and 1.33 μm of Nd : Ca 4YO(BO 3) 3 and Nd : Ca 4GdO(BO 3) 3 crystals

NASA Astrophysics Data System (ADS)

Wang, Changqing; Zhang, Huaijin; Meng, Xianlin; Zhu, Li; Chow, Y. T.; Liu, Xuesong; Cheng, Ruiping; Yang, Zhaohe; Zhang, Shaojun; Sun, Lianke

2000-11-01

Nd : Ca 4YO(BO 3) 3 (Nd : YCOB) and Nd : Ca 4GdO(BO 3) 3 (Nd : GdCOB) crystals were grown by Czochralski method. Thermal expansion and specific heat of these two crystals were experimentally determined. Their fluorescence spectra were measured within the range from 1000 to 1500 nm. Laser output experiments at 1.06 and 1.33 μm of Nd : YCOB and Nd : GdCOB crystals were performed with a cw Ti : sapphire laser as the pump source.

High-quality bulk hybrid perovskite single crystals within minutes by inverse temperature crystallization

NASA Astrophysics Data System (ADS)

Saidaminov, Makhsud I.; Abdelhady, Ahmed L.; Murali, Banavoth; Alarousu, Erkki; Burlakov, Victor M.; Peng, Wei; Dursun, Ibrahim; Wang, Lingfei; He, Yao; Maculan, Giacomo; Goriely, Alain; Wu, Tom; Mohammed, Omar F.; Bakr, Osman M.

2015-07-01

Single crystals of methylammonium lead trihalide perovskites (MAPbX3; MA=CH3NH3+, X=Br- or I-) have shown remarkably low trap density and charge transport properties; however, growth of such high-quality semiconductors is a time-consuming process. Here we present a rapid crystal growth process to obtain MAPbX3 single crystals, an order of magnitude faster than previous reports. The process is based on our observation of the substantial decrease of MAPbX3 solubility, in certain solvents, at elevated temperatures. The crystals can be both size- and shape-controlled by manipulating the different crystallization parameters. Despite the rapidity of the method, the grown crystals exhibit transport properties and trap densities comparable to the highest quality MAPbX3 reported to date. The phenomenon of inverse or retrograde solubility and its correlated inverse temperature crystallization strategy present a major step forward for advancing the field on perovskite crystallization.

Characterization of Thallium Bromide Detectors Made From Material Purified by the Filter Method

NASA Astrophysics Data System (ADS)

Onodera, Toshiyuki; Hitomi, Keitaro; Tada, Tsutomu; Shoji, Tadayoshi; Mochizuki, Katsumi

2013-10-01

Thallium bromide (TlBr) has been regarded as candidate detector materials for the gamma-ray spectrometers operating at room temperature. In this study, a simple and rapid method, the filter method, was performed to purify a raw TlBr material used for fabrication of TlBr detectors. The material was loaded on shards of crashed quartz and installed in a Pyrex tube, and was melted using a furnace. A purified material passing through interspaces of the shards of quartz was collected in a quartz ampoule located at the outlet of the Pyrex tube. After the purification, impurities colored black extracted from the raw material remained. TlBr crystals were then grown by the travelling molten zone method both from the raw material and the purified material. TlBr detectors were fabricated from the grown crystals, and were characterized by measuring mobility-lifetime products (μτ) for carriers and gamma-ray spectra ( 137Cs) at room temperature. μτ for electrons of a TlBr detector fabricated from the purified material was around 5 times higher than that of a detector fabricated from the raw material.

Growth of high quality and large-sized Rb 0.3MoO 3 single crystals by molten salt electrolysis method

NASA Astrophysics Data System (ADS)

Wang, Junfeng; Xiong, Rui; Yi, Fan; Yin, Di; Ke, Manzhu; Li, Changzhen; Liu, Zhengyou; Shi, Jing

2005-05-01

High quality and large-sized Rb 0.3MoO 3 single crystals were synthesized by molten salt electrolysis method. X-ray diffraction (XRD) patterns and rocking curves, as well as the white beam Laue diffraction of X-ray images show the crystals grown by this method have high quality. The lattice constants evaluated from XRD patterns are a0=1.87 nm, b0=0.75 nm, c0=1.00 nm, β=118.83∘. The in situ selected area electron diffraction (SAED) patterns along the [101¯], [11¯1¯] and [103¯] zone axes at room temperature indicate that the Rb 0.3MoO 3 crystal possess perfect C-centered symmetry. Temperature dependence of the resistivity shows this compound undergoes a metal to semiconductor transition at 183 K.

Czochralski growth of 2 in. Ca3Ta(Ga,Al)3Si2O14 single crystals for piezoelectric applications

NASA Astrophysics Data System (ADS)

Yoshikawa, Akira; Shoji, Yasuhiro; Ohashi, Yuji; Yokota, Yuui; Chani, Valery I.; Kitahara, Masanori; Kudo, Tetsuo; Kamada, Kei; Kurosawa, Shunsuke; Medvedev, Andrey; Kochurikhin, Vladimir

2016-10-01

Growth of 2-in. diameter Al-substituted Ca3TaGa3Si2O14 crystals by Czochralski method is reported. The crystals were grown from the melt of Ca3TaGa1.5Al1.5Si2O14 composition and had langasite structure. No inclusions of secondary phases were detected in these crystals. The Ca3Ta(Ga,Al)3Si2O14 mixed crystals produced using non-substituted Ca3TaGa3Si2O14 seeds were defective. They had cracks and/or poly-crystalline structure. However, those grown on the seed of approximately Ca3TaGa1.5Al1.5Si2O14 composition were defect-free. Phase diagram of the Ca3TaGa3Si2O14-Ca3TaAl3Si2O14 pseudo-binary system and segregation phenomenon are discussed in some details. Homogeneity of the crystals was evaluated by measuring 2D-mapping of leaky surface acoustic wave (LSAW) velocities for Y-cut Ca3TaGa1.5Al1.5Si2O14 substrate. Although some inhomogeneities were observed due to slight variations in chemical composition, the crystal had acceptable homogeneity for applications in acoustic wave devices exhibiting the LSAW velocity variation within ±0.048%.

Phase transformations, anisotropic pyroelectric energy harvesting and electrocaloric properties of (Pb,La)(Zr,Sn,Ti)O3 single crystals.

PubMed

Zhuo, Fangping; Li, Qiang; Gao, Jinghan; Yan, Qingfeng; Zhang, Yiling; Xi, Xiaoqing; Chu, Xiangcheng

2017-05-31

(Pb,La)(Zr,Sn,Ti)O 3 (PLZST) single crystals with their chemical composition located at the tetragonal antiferroelectric region are grown via the flux method in a PbO-PbF 2 -B 2 O 3 mixture. Segregation of the Ti 4+ component in the as-grown crystals is observed due to the strong affinity between the oxygen anion and Ti 4+ ions. The critical electric field of the antiferroelectric to ferroelectric phase transition is determined to be about 0.5 kV mm -1 . The electric field induced ferroelectric phase transforms back into the antiferroelectric phase at a depolarization temperature of 125 °C. Anisotropy of the harvested energy density and electrocaloric behaviors are achieved for the [100], [110] and [111]-oriented PLZST crystals. Based on the thermodynamic theory approach, all the abovementioned behaviors originate from the anisotropic total entropy change. Enhanced electrocaloric strength (0.3 K mm kV -1 ) and the harvested energy density of 0.62 J cm -3 are obtained in the [111]-oriented PLZST crystals. Our results demonstrate the competence of PLZST single crystals for cooling devices and pyroelectric energy harvesting and provide new opportunities to improve energy harvesting density and electrocaloric properties via the anisotropic structural layout, which make the PLZST crystals attractive for solid state cooling devices and energy conversion technologies.

Crystallization and X-ray diffraction analysis of a putative bacterial class I labdane-related diterpene synthase.

PubMed

Serrano-Posada, Hugo; Centeno-Leija, Sara; Rojas-Trejo, Sonia; Stojanoff, Vivian; Rodríguez-Sanoja, Romina; Rudiño-Piñera, Enrique; Sánchez, Sergio

2015-09-01

Labdane-related diterpenoids are natural products with potential pharmaceutical applications that are rarely found in bacteria. Here, a putative class I labdane-related diterpene synthase (LrdC) identified by genome mining in a streptomycete was successfully crystallized using the microbatch method. Crystals of the LrdC enzyme were obtained in a holo form with its natural cofactor Mg(2+) (LrdC-Mg(2+)) and in complex with inorganic pyrophosphate (PPi) (LrdC-Mg(2+)-PPi). Crystals of native LrdC-Mg(2+) diffracted to 2.50 Å resolution and belonged to the trigonal space group P3221, with unit-cell parameters a = b = 107.1, c = 89.2 Å. Crystals of the LrdC-Mg(2+)-PPi complex grown in the same conditions as the native enzyme with PEG 8000 diffracted to 2.36 Å resolution and also belonged to the trigonal space group P3221. Crystals of the LrdC-Mg(2+)-PPi complex grown in a second crystallization condition with PEG 3350 diffracted to 2.57 Å resolution and belonged to the monoclinic space group P21, with unit-cell parameters a = 49.9, b = 104.1, c = 66.5 Å, β = 111.4°. The structure was determined by the single-wavelength anomalous dispersion (SAD) technique using the osmium signal from a potassium hexachloroosmate (IV) derivative.

Tuning the structure of CsCaI3:Eu via substitution of bromine for iodine

NASA Astrophysics Data System (ADS)

Loyd, M.; Lindsey, A.; Stand, L.; Zhuravleva, M.; Melcher, C. L.; Koschan, M.

2017-06-01

CsCaI3:Eu is a promising scintillator material that can be grown from the melt, but undergoes a tetragonal to orthorhombic phase transition upon cooling at 255 °C, causing twinning and cloudiness. The purpose of this work is to suppress this solid to solid phase transition in the CsCaI3:Eu scintillator, which has a light yield of ∼40000 ph/MeV and energy resolution at 662 keV of ∼4%, by halide replacement to form the compound CsCaBrxI3-x. Crystals 8 cm3 in volume were grown using the vertical Bridgman method with varying bromine content from x = 0.2 to x = 1, resulting in improved transparency for crystals with bromine content x > 0.6. Powder X-ray diffraction data coupled with differential scanning calorimetry and radioluminescence measurements were used to investigate structural modifications, melting point dependence and spectral emission dependence on the bromine/iodine ratio. Partial replacement of iodine by bromine improves optical quality and scintillation properties by stabilizing the structure, rendering it useful for isotope identification for national security applications. The composition CsCaBr0.8I2.2:Eu was determined to be the best combination of improved structure and performance, and larger 22 and 38 mm Ø crystals were grown for further evaluation. Large size slabs of these crystals showed good crystal quality and improved performance over CsCaI3Eu with 8.4% and 9.5% energy resolution at 662 keV, respectively.