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Sample records for ni-particle-dispersed alkaline niobate

  1. Lithium niobate explosion monitor

    DOEpatents

    Bundy, C.H.; Graham, R.A.; Kuehn, S.F.; Precit, R.R.; Rogers, M.S.

    1990-01-09

    Monitoring explosive devices is accomplished with a substantially z-cut lithium niobate crystal in abutment with the explosive device. Upon impact by a shock wave from detonation of the explosive device, the crystal emits a current pulse prior to destruction of the crystal. The current pulse is detected by a current viewing transformer and recorded as a function of time in nanoseconds. In order to self-check the crystal, the crystal has a chromium film resistor deposited thereon which may be heated by a current pulse prior to detonation. This generates a charge which is detected by a charge amplifier. 8 figs.

  2. Lithium niobate explosion monitor

    DOEpatents

    Bundy, Charles H.; Graham, Robert A.; Kuehn, Stephen F.; Precit, Richard R.; Rogers, Michael S.

    1990-01-01

    Monitoring explosive devices is accomplished with a substantially z-cut lithium niobate crystal in abutment with the explosive device. Upon impact by a shock wave from detonation of the explosive device, the crystal emits a current pulse prior to destruction of the crystal. The current pulse is detected by a current viewing transformer and recorded as a function of time in nanoseconds. In order to self-check the crystal, the crystal has a chromium film resistor deposited thereon which may be heated by a current pulse prior to detonation. This generates a charge which is detected by a charge amplifier.

  3. Synthesis of transparent aqueous sols of colloidal layered niobate nanocrystals at room temperature.

    PubMed

    Ban, Takayuki; Yoshikawa, Shogo; Ohya, Yutaka

    2011-12-01

    Transparent aqueous sols of colloidal tetramethylammonium niobate nanocrystals were synthesized by mixing tetramethylammonium hydroxide (TMAOH), niobium ethoxide, and water at TMAOH/Nb≥0.7 at room temperature. The X-ray diffraction patterns of the thin films prepared by evaporating the colloidal solutions on a glass substrate indicated that the colloidal niobate had a layered crystalline structure. Two types of layered structures are known as a layered niobate, i.e. M(4)Nb(6)O(17)·nH(2)O and MNb(3)O(8) (M=H, H(3)O, or alkaline metal). Raman spectra and electron diffraction suggested that the niobate nanocrystals were similar in crystal structure to M(4)Nb(6)O(17)·nH(2)O compounds. Moreover, when niobium oxide thin films were fabricated from the niobate colloidal solutions by the sol-gel method, oriented T-Nb(2)O(5) thin films, whose c-axis was parallel to the substrate surface, were obtained. The orientation of the thin films was probably attributed to the layered structure of the colloidal niobate nanocrystals. PMID:21903222

  4. Niobate-based octahedral molecular sieves

    DOEpatents

    Nenoff, Tina M.; Nyman, May D.

    2006-10-17

    Niobate-based octahedral molecular sieves having significant activity for multivalent cations and a method for synthesizing such sieves are disclosed. The sieves have a net negatively charged octahedral framework, comprising niobium, oxygen, and octahedrally coordinated lower valence transition metals. The framework can be charge balanced by the occluded alkali cation from the synthesis method. The alkali cation can be exchanged for other contaminant metal ions. The ion-exchanged niobate-based octahedral molecular sieve can be backexchanged in acidic solutions to yield a solution concentrated in the contaminant metal. Alternatively, the ion-exchanged niobate-based octahedral molecular sieve can be thermally converted to a durable perovskite phase waste form.

  5. Niobate-based octahedral molecular sieves

    DOEpatents

    Nenoff, Tina M.; Nyman, May D.

    2003-07-22

    Niobate-based octahedral molecular sieves having significant activity for multivalent cations and a method for synthesizing such sieves are disclosed. The sieves have a net negatively charged octahedral framework, comprising niobium, oxygen, and octahedrally coordinated lower valence transition metals. The framework can be charge balanced by the occluded alkali cation from the synthesis method. The alkali cation can be exchanged for other contaminant metal ions. The ion-exchanged niobate-based octahedral molecular sieve can be backexchanged in acidic solutions to yield a solution concentrated in the contaminant metal. Alternatively, the ion-exchanged niobate-based octahedral molecular sieve can be thermally converted to a durable perovskite phase waste form.

  6. Stable liquid crystalline phases of colloidally dispersed exfoliated layered niobates.

    PubMed

    Nakato, Teruyuki; Miyamoto, Nobuyoshi; Harada, Akiko

    2004-01-01

    Colloidally dispersed niobium oxide nanosheets obtained by exfoliation of layered niobates HNb(3)O(8) and HTiNbO(5) formed stable liquid crystalline phases; their liquid crystallinity was dependent on the niobate species exfoliated. PMID:14737341

  7. Chemically Prepared Lead Magnesium Niobate Dielectrics

    SciTech Connect

    Tuttle, B.A.; Voigt, J.A.; Sipola, D.L.; Olson, W.R.; Goy, D.M.

    1998-01-01

    A chemical solution powder synthesis technique has been developed that produces fine uniform powders of lead magnesium niobate (PMN) with 60 to 80 nm crystallite size. The synthesis technique was based on the dissolution of lead acetate and alkoxide precursors in acetic acid followed by precipitation with oxalic acid/propanol solutions. Lead magnesium niobate ceramics fabricated from these chemically derived powders had smaller, more uniform grain size and higher dielectric constants than ceramics fabricated from mixed oxide powders that were processed under similar thermal conditions.

  8. Transformation of potassium Lindquist hexaniobate to various potassium niobates: solvothermal synthesis and structural evolution mechanism.

    PubMed

    Kong, Xingang; Hu, Dengwei; Wen, Puhong; Ishii, Tomohiko; Tanaka, Yasuhiro; Feng, Qi

    2013-06-01

    This paper introduces the formation reactions and reaction mechanisms of a series of potassium niobates from a potassium salt of the Lindquist hexaniobate [Nb6O19](8-) ion under solvothermal conditions. The structure and particle morphology of the potassium niobate product can be controlled easily with the reaction solution alkalinity using this solvothermal process. KNb3O8 with a plate-like morphology, K4Nb6O17·4.5H2O with a plate-like morphology, a new phase of K2Nb2O6·H2O with fibrous morphology, KNbO3 perovskites with cubic morphology are obtained at pH = 5.5, and in 0.3, 0.5, 1.0 mol L(-1) KOH solutions at 230 °C, respectively. The reaction conditions are much milder than those in the normal hydrothermal process. Furthermore, the K2Nb2O6·H2O fibers can be topotactically transformed into KNbO3 fibers, Nb2O5 fibers after H(+)-exchange-treatment, and LiNbO3 fibers after Li(+)-exchange-treatment by heat-treatments at 730, 560, and 520 °C, respectively. The formation reaction and structure of these potassium niobates were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), energy-dispersive spectroscopy (EDS), Raman spectra and TG-DTA. The formation mechanism of this series of potassium niobates from the [Nb6O19](8-) precursor is systematically explained via the correlation between the octahedrons [NbO6] sharing forms in the precursor structure and in the product structures. PMID:23545951

  9. Chemically prepared lead magnesium niobate dielectrics

    SciTech Connect

    Tuttle, B.A.; Voigt, J.A.; Sipola, D.L.; Olson, W.R.; Goy, D.M.

    1998-11-01

    A chemical solution powder synthesis technique has been developed that produces first, uniform powders of lead magnesium niobate (PMN) with 60 to 80 nm crystallite size. The synthesis technique was based on the dissolution of lead acetate and alkoxide precursors in acetic acid followed by precipitation with oxalic acid/propanol solutions. Lead magnesium niobate ceramics fabricated from these chemically derived powders had smaller, more uniform grain size and higher dielectric constants than ceramics fabricated from mixed oxide powders that were processed under similar thermal conditions. Chem-prep PMN dielectrics with peak dielectric constants greater than 22,000 and polarizations in excess of 29 {micro}C/cm{sup 2} were obtained for 1,100 C firing treatments. Substantial decreases in dielectric constant and polarization were measured for chemically prepared PMN ceramics fired at lower temperatures, consistent with previous work on mixed oxide materials.

  10. Lead magnesium niobate actuator for micropositioning

    DOEpatents

    Swift, C.D.; Bergum, J.W.

    1994-10-25

    An improved lead magnesium niobate actuator is disclosed comprising a cylindrical lead magnesium niobate crystal stack mounted in a cylindrical casing wherein a bias means, such as one or more belleville washers, is located between one end of the crystal stack and a partially closed end of the casing; and adjustment means are provided which bear against the opposite end of the crystal stack, whereby an adjustable compressive force is constantly applied against the crystal stack, whether the crystal stack is actuated in an extended position, or is in an unactuated contracted position. In a preferred embodiment, cooling ports are provided for the circulation of coolant in the actuator to cool the crystal stack, and provision is made for removal and replacement of the crystal stack without disconnecting the actuator from the external device being actuated. 3 figs.

  11. Lead magnesium niobate actuator for micropositioning

    DOEpatents

    Swift, Charles D.; Bergum, John W.

    1994-01-01

    An improved lead magnesium niobate actuator is disclosed comprising a cylindrical lead magnesium niobate crystal stack mounted in a cylindrical casing wherein a bias means, such as one or more belleville washers, is located between one end of the crystal stack and a partially closed end of the casing; and adjustment means are provided which bear against the opposite end of the crystal stack, whereby an adjustable compressive force is constantly applied against the crystal stack, whether the crystal stack is actuated in an extended position, or is in an unactuated contracted position. In a preferred embodiment, cooling ports are provided for the circulation of coolant in the actuator to cool the crystal stack, and provision is made for removal and replacement of the crystal stack without disconnecting the actuator from the external device being actuated.

  12. Strip loaded waveguide on lithium niobate thin films

    NASA Astrophysics Data System (ADS)

    Roussey, Matthieu; Karvinen, Petri; Häyrinen, Markus; Honkanen, Seppo; Kuittinen, Markku

    2016-02-01

    We present the experimental demonstration of a strip loaded waveguide on crystalline lithium niobate thin film. The structure consists in a 1 μm-wide and 200 nm-thick titanium dioxide strip waveguide on a 700 nm lithium niobate slab waveguide. It operates at the telecom wavelength for a TE-polarized light.

  13. Integrated Optical Heterodyne Interferometer in Lithium Niobate

    NASA Astrophysics Data System (ADS)

    Rubiyanto, A.; Herrmann, H.; Ricken, R.; Tian, F.; Sohler, W.

    A high performance integrated acousto-optical heterodyne interferometer has been developed for vibration measurement. All components including an acousto-optical TE-TM mode converters, two electro-optical TE-TM converters, two polarization splitters and two phase shifters are integrated on a X-cut Lithium Niobate substrate. The fully packaged optical integrated circuit (optical-IC) coupling with three fibers optics pigtails gave a signal-to-noise ratio of 69 dB with at 3 kHz bandwidth by using a commercial DFB laser diode as a light source with 1561 nm emission wavelength and a PIN-FET balanced receiver.

  14. Single potassium niobate nano/microsized particles as local mechano-optical Brownian probes.

    PubMed

    Mor, Flavio M; Sienkiewicz, Andrzej; Magrez, Arnaud; Forró, László; Jeney, Sylvia

    2016-03-28

    Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal fluctuations and optical forces of singly-trapped KNbO3 particles within the optical trapping volume of a PFM microscope. We also show that, under near-infrared (NIR) excitation of the highly focused laser beam of the PFM microscope, a single optically-trapped KNbO3 particle reveals a strong SHG signal manifested by a narrow peak (λ(em) = 532 nm) at half the excitation wavelength (λ(ex) = 1064 nm). Moreover, we demonstrate that the thus induced SHG emission can be used as a local light source that is capable of optically exciting molecules of an organic dye, Rose Bengal (RB), which adhere to the particle surface, through the mechanism of luminescence energy transfer (LET). PMID:26956197

  15. Micromachining Lithium Niobate for Rapid Prototyping of Resonant Biosensors

    NASA Astrophysics Data System (ADS)

    Abdoon Al-Shibaany, Zeyad Yousif; Hedley, John; Huo, Dehong; Hu, Zhongxu

    2014-07-01

    Lithium niobate material is widely used in MEMS application due to its piezoelectric properties. This paper presents the micromachining process of lithium niobate to rapid prototype a resonant biosensor design. A high precision CNC machine was used to machine a sample of lithium niobate material at 5 different spindle speeds to find out the best conditions to machine this brittle material. A qualitative visual check of the surface was performed by using scanning electron microscopy, surface roughness was quantitatively investigated using an optical surface profiler and Raman spectroscopy to check the strain of the surface. Results show that the surface quality of the lithium niobate was significantly affected by the spindle speed with optimum conditions at 70k rpm giving a strained surface with 500 nm rms roughness.

  16. Study of multiple hologram recording in lithium niobate

    NASA Technical Reports Server (NTRS)

    Gaylord, T. K.; Callen, W. R.

    1976-01-01

    The results of a number of theoretical and experimental studies relating to multiple hologram recording in lithium niobate are reported. The analysis of holographic gratings stored in lithium niobate has been extended to cover a more realistic range of physical situations. A new successful dynamic (feedback) theory for describing recording, nondestructive reading, erasure, enhancement, and angular sensitivity has been developed. In addition, the possible architectures of mass data storage systems have been studied.

  17. Diamond turning of lithium niobate for optical applications

    SciTech Connect

    Fuchs, B.A.; Syn, C.; Velsko, S.P. )

    1992-09-20

    We have investigated the surfae finishing of lithium niobate by using the single-point diamond turning technique. Surface finishes of better than 5 nm rms on {ital z}-oriented samples have been achieved. However, tool wear and spalling are much more significant with lithium niobate than with materials such as the crystals KDP and LAP. We present preliminary results comparing the optical damage thresholds of polished and diamond-turned samples.

  18. Synthesis and Characterization of β Nickel Niobate

    NASA Astrophysics Data System (ADS)

    Munsie, Timothy; Millington, Anna; Dabkowska, Hanna; Britten, Jim; Luke, Graeme

    2015-03-01

    Members of the niobate family (ANb2O6, A=Ni, Co, Fe, Mn) are known to crystallize in the columbite structure with zig-zag chains of the metallic and typically magnetic cation, giving rise to a quasi-one-dimensional magnetic system. In our attempts to synthesize NiNb2O6 in its columbite structure, we discovered a previously unreported allotrope, β-NiNb2O6, with a completely different crystalline structure, magnetic environment and magnetic properties. This talk will discuss the difficulties with respect to synthesis via the optical floating zone (OFZ) technique, the results of our structural refinement utilizing single crystal x-ray diffraction, and both magnetic and transport measurements of this materials physical properties.

  19. Optical cleaning of congruent lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Kösters, M.; Sturman, B.; Werheit, P.; Haertle, D.; Buse, K.

    2009-09-01

    Lithium niobate (LiNbO3), also called the `silicon of photonics', is indispensable in advanced photonics and nonlinear optics. For many applications, however, the material is too polluted by transition metals, which are unavoidable at the parts per million level. These impurities serve as sources and traps for photoelectrons, causing optical damage and hampering the usability of LiNbO3. Efforts have therefore been made to get rid of the photoexcitable electrons. Here we introduce a method termed `optical cleaning'. We show theoretically and experimentally that, if the material is heated to moderate temperatures, allowing ions to migrate and to maintain charge neutrality, an appropriately moving light beam pushes photoexcitable electrons out of the illuminated region like a brush, and provides exponential cleaning. This promises purification levels that are beyond the reach of current technologies.

  20. Single potassium niobate nano/microsized particles as local mechano-optical Brownian probes

    NASA Astrophysics Data System (ADS)

    Mor, Flavio M.; Sienkiewicz, Andrzej; Magrez, Arnaud; Forró, László; Jeney, Sylvia

    2016-03-01

    Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal fluctuations and optical forces of singly-trapped KNbO3 particles within the optical trapping volume of a PFM microscope. We also show that, under near-infrared (NIR) excitation of the highly focused laser beam of the PFM microscope, a single optically-trapped KNbO3 particle reveals a strong SHG signal manifested by a narrow peak (λem = 532 nm) at half the excitation wavelength (λex = 1064 nm). Moreover, we demonstrate that the thus induced SHG emission can be used as a local light source that is capable of optically exciting molecules of an organic dye, Rose Bengal (RB), which adhere to the particle surface, through the mechanism of luminescence energy transfer (LET).Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal

  1. Precise, reproducible nano-domain engineering in lithium niobate crystals

    SciTech Connect

    Boes, Andreas Sivan, Vijay; Ren, Guanghui; Yudistira, Didit; Mitchell, Arnan; Mailis, Sakellaris; Soergel, Elisabeth

    2015-07-13

    We present a technique for domain engineering the surface of lithium niobate crystals with features as small as 100 nm. A film of chromium (Cr) is deposited on the lithium niobate surface and patterned using electron beam lithography and lift-off and then irradiated with a wide diameter beam of intense visible laser light. The regions patterned with chromium are domain inverted while the uncoated regions are not affected by the irradiation. With the ability to realize nanoscale surface domains, this technique could offer an avenue for fabrication of nano-photonic and phononic devices.

  2. Precise, reproducible nano-domain engineering in lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Boes, Andreas; Sivan, Vijay; Ren, Guanghui; Yudistira, Didit; Mailis, Sakellaris; Soergel, Elisabeth; Mitchell, Arnan

    2015-07-01

    We present a technique for domain engineering the surface of lithium niobate crystals with features as small as 100 nm. A film of chromium (Cr) is deposited on the lithium niobate surface and patterned using electron beam lithography and lift-off and then irradiated with a wide diameter beam of intense visible laser light. The regions patterned with chromium are domain inverted while the uncoated regions are not affected by the irradiation. With the ability to realize nanoscale surface domains, this technique could offer an avenue for fabrication of nano-photonic and phononic devices.

  3. Luminescence of perovskite-like niobates and tantalates

    SciTech Connect

    Blasse, G. . Fysisch Lab.); Brixner, L.H. and Co., Wilmington, DE . Central Research and Development Dept.)

    1989-03-01

    The luminescence of perovskite-like niobates and tantalates is compared and discussed in connection with that of titanates. The luminescence properties are strongly related to each other. Electronic delocalization in corner-sharing octahedra is shown to play an important role.

  4. Micro- and nano-domain engineering in lithium niobate

    NASA Astrophysics Data System (ADS)

    Shur, V. Ya.; Akhmatkhanov, A. R.; Baturin, I. S.

    2015-12-01

    The physical basis of the domain engineering in ferroelectrics and its application to lithium niobate crystals were reviewed. The unified kinetic approach to the domain structure evolution in electric field was formulated and its validity for understanding the variety of observed domain evolution scenarios was demonstrated. The kinetics and statics of the domain structure in the crystals of lithium niobate family including congruent, stoichiometric, and MgO doped ones have been discussed. The main stages of the periodical poling process and related problems have been pointed out. The basic poling techniques applied for creation of the periodical domain structures in bulk crystals and waveguides were compared. The recent applications of the periodically poled lithium niobate for light frequency conversion using second harmonic generation and optical parametric oscillation, excitation of the surface acoustic waves, and generation of terahertz radiation have been discussed. The special attention has been paid for achievements in fabrication of high-power optical parametric oscillation and integrated optical devices with periodically poled lithium niobate. The future trends in periodical poling and development of the nanodomain engineering which will allow to create the nanoscale domain patterns necessary for utilization of the new nonlinear interactions were reviewed.

  5. Study of multiple hologram recording in lithium niobate

    NASA Technical Reports Server (NTRS)

    Gaylord, T. K.; Callen, W. R.

    1974-01-01

    The results of detailed experimental and theoretical considerations relating to multiple hologram recording in lithium niobate are reported. The following problem areas are identified and discussed: (1) the angular selectivity of the stored holograms, (2) interference effects due to the crystal surfaces, (3) beam divergence effects, (4) material recording sensitivity, and (5) scattered light from material inhomogeneities.

  6. Micro- and nano-domain engineering in lithium niobate

    SciTech Connect

    Shur, V. Ya.; Akhmatkhanov, A. R.; Baturin, I. S.

    2015-12-15

    The physical basis of the domain engineering in ferroelectrics and its application to lithium niobate crystals were reviewed. The unified kinetic approach to the domain structure evolution in electric field was formulated and its validity for understanding the variety of observed domain evolution scenarios was demonstrated. The kinetics and statics of the domain structure in the crystals of lithium niobate family including congruent, stoichiometric, and MgO doped ones have been discussed. The main stages of the periodical poling process and related problems have been pointed out. The basic poling techniques applied for creation of the periodical domain structures in bulk crystals and waveguides were compared. The recent applications of the periodically poled lithium niobate for light frequency conversion using second harmonic generation and optical parametric oscillation, excitation of the surface acoustic waves, and generation of terahertz radiation have been discussed. The special attention has been paid for achievements in fabrication of high-power optical parametric oscillation and integrated optical devices with periodically poled lithium niobate. The future trends in periodical poling and development of the nanodomain engineering which will allow to create the nanoscale domain patterns necessary for utilization of the new nonlinear interactions were reviewed.

  7. Adsorptive and photocatalytic removal of phenol by layered niobates organically modified through intercalation and silylation.

    PubMed

    Kiba, Shosuke; Haga, Jun-ichi; Hashimoto, Sachika; Nakato, Teruyuki

    2010-12-01

    Layered hexaniobate K4Nb6O17 was modified with dodecylammonium ions and octadecyltrimethoxysilane molecules, which were held in the interlayer spaces by electrostatic interactions and covalent attachment to the layers, respectively. Interlayer spacing of the niobate was expanded by incorporation of the bulky organic species. Vapor adsorption isotherms of benzene and water indicated hydrophobic interlayer microenvironments of the organically modified niobates. Both of the modified niobates fairly adsorbed phenol dissolved in water. The photocatalytic activity of hexaniobate allowed the organically modified materials to photocatalytically decompose phenol upon UV irradiation. Decomposition time courses and quantitative analysis of phenol present in the system indicated that the phenol molecules adsorbed on the niobates were preferentially degraded. XRD and IR analyses of the modified niobates indicated that the silylated niobate was more durable than the ion-exchanged sample; the former kept the structure during the photocatalytic process while the latter was partly collapsed. PMID:21121337

  8. Nonlinear diffusion model for annealed proton-exchanged waveguides in zirconium-doped lithium niobate.

    PubMed

    Langrock, Carsten; Roussev, Rostislav V; Nava, Giovanni; Minzioni, Paolo; Argiolas, Nicola; Sada, Cinzia; Fejer, Martin M

    2016-08-20

    Photorefractive-damage- (PRD) resistant zirconium-oxide-doped lithium niobate is investigated as a substrate for the realization of annealed proton-exchanged (APE) waveguides. Its advantages are a favorable distribution coefficient, PRD resistance comparable to magnesium-oxide-doped lithium niobate, and a proton-diffusion behavior resembling congruent lithium niobate. A 1D model for APE waveguides was developed based on a previous model for congruently melting lithium niobate. Evidence for a nonlinear index dependence on concentration was found. PMID:27556972

  9. ALP (Alkaline Phosphatase) Test

    MedlinePlus

    ... known as: ALK PHOS; Alkp Formal name: Alkaline Phosphatase Related tests: AST ; ALT ; GGT ; Bilirubin ; Liver Panel ; Bone Markers ; Alkaline Phosphatase Isoenzymes; Bone Specific ALP All content on Lab ...

  10. Polaron luminescence in iron-doped lithium niobate

    NASA Astrophysics Data System (ADS)

    Harhira, A.; Guilbert, L.; Bourson, P.; Rinnert, H.

    2008-09-01

    Photoluminescence related to the bound polaron Nb{Li/4+} is investigated as a function of temperature and incident light intensity in iron-doped lithium niobate crystals with various iron concentrations. Experiments are done under constant-wave (CW) and pulsed illumination. Its found that the decay time is always monoexponential. The radiative lifetime, the activation energy of the nonradiative lifetime and the quenching temperature are only weakly sensitive to iron concentration. On the other hand, the magnitude of the photoluminescence signal seems strongly correlated to the Fe2+ concentration, and the superlinear regime evidenced at low CW illumination definitely confirms that polaron excitation in lithium niobate is a two-step process.

  11. Shock-induced luminescence from Z-cut lithium niobate

    SciTech Connect

    Brannon, P.J.; Morris, R.W.; Asay, J.R.

    1985-03-01

    Shock-induced luminescence from lithium niobate has been studied in the stress range 1.6--21.0 GPa. Both fast-framing photography and five-channel optical pyrometry were used to observe the luminescence. The framing photography showed that the emission pattern is heterogeneous for stresses just above the dynamic yield point. A further increase of the stress resulted in a pattern which was essentially homogeneous to within the experimental spatial resolution of about 30 ..mu..m. Narrowband filters and photomultiplier tubes were used in the optical pyrometry experiments. A broadband spectrum with a peak near 700 nm was observed. A plot of the energy dissipated by the shock versus shock stress correlates very well with a plot of the 700-nm intensity versus shock stress. The mechanism for light emission in lithium niobate appears to be closely related to the dynamic yielding process.

  12. Photorefractive effect at 775 nm in doped lithium niobate crystals

    SciTech Connect

    Nava, G.; Minzioni, P.; Cristiani, I.; Degiorgio, V.; Argiolas, N.; Bazzan, M.; Ciampolillo, M. V.; Pozza, G.; Sada, C.

    2013-07-15

    The photorefractive effect induced by 775-nm laser light on doped lithium niobate crystals is investigated by the direct observation in the far field of the transmitted-beam distortion as a function of time. Measurements performed at various Zr-doping concentrations and different light intensities show that the 775-nm light beam induces a steady-state photorefractive effect comparable to that of 532-nm light, but the observed build-up time of the photovoltaic field is longer by three-orders of magnitude. The 775-nm photorefractivity of lithium niobate crystals doped with 3 mol. % ZrO{sub 2} or with 5.5 mol. % MgO is found to be negligible.

  13. Optical waveguides in lithium niobate: Recent developments and applications

    NASA Astrophysics Data System (ADS)

    Bazzan, Marco; Sada, Cinzia

    2015-12-01

    The state of the art of optical waveguide fabrication in lithium niobate is reviewed, with particular emphasis on new technologies and recent applications. The attention is mainly devoted to recently developed fabrication methods, such as femtosecond laser writing, ion implantation, and smart cut waveguides as well as to the realization of waveguides with tailored functionalities, such as photorefractive or domain engineered structures. More exotic systems, such as reconfigurable and photorefractive soliton waveguides, are also considered. Classical techniques, such as Ti in-diffusion and proton exchange, are cited and briefly reviewed as a reference standpoint to highlight the recent developments. In all cases, the application-oriented point of view is preferred, in order to provide the reader with an up-to date panorama of the vast possibilities offered by lithium niobate to integrated photonics.

  14. Optical waveguides in lithium niobate: Recent developments and applications

    SciTech Connect

    Bazzan, Marco Sada, Cinzia

    2015-12-15

    The state of the art of optical waveguide fabrication in lithium niobate is reviewed, with particular emphasis on new technologies and recent applications. The attention is mainly devoted to recently developed fabrication methods, such as femtosecond laser writing, ion implantation, and smart cut waveguides as well as to the realization of waveguides with tailored functionalities, such as photorefractive or domain engineered structures. More exotic systems, such as reconfigurable and photorefractive soliton waveguides, are also considered. Classical techniques, such as Ti in-diffusion and proton exchange, are cited and briefly reviewed as a reference standpoint to highlight the recent developments. In all cases, the application-oriented point of view is preferred, in order to provide the reader with an up-to date panorama of the vast possibilities offered by lithium niobate to integrated photonics.

  15. Luminescence from chromium-neodymium-doped lithium niobate

    NASA Astrophysics Data System (ADS)

    Mahpoud, S.; Chamiel, N.; Weiss, A. M.; Rosenbluh, M.; Herman, A.; Shoham, A.; Lipavsky, B.; Rotman, S. R.

    1999-10-01

    Luminescence from chromium-neodymium-doped lithium niobate (LiNbO 3) was experimentally measured to determine the degree of non-radiative energy transfer between chromium and neodymium ions. Evidence is presented for two different time constants for emission from chromium ions in the material, indicating that non-radiative transfer does occur. Differences between quasi-continuous pumping and pulsed excitation are discussed.

  16. Selective chemical etching of iron-doped lithium niobate

    SciTech Connect

    Alekseeva, Z.E.; Vorob'eva, L.B.; Evlanova, N.F.

    1987-01-01

    Addition of the dopant changed the way in which the lithium niobate crystal etched. As a result, nonpolar slices clearly showed microdomain etch figures that enabled determination of surface sign as well as <0110> and <0001> directions on the (2110) planes. Mechanical treatment was shown to be one of the reasons for microdomain destruction at the surface layer. The thickness of the damaged layer may be determined by the width of the edge zone displaying a high microdomain density at the (0001) plane.

  17. Fundamental Study of a Stacked Lithium Niobate Transducer

    NASA Astrophysics Data System (ADS)

    Morita, Takeshi; Niino, Toshiki; Asama, Hajime; Tashiro, Hideo

    2001-05-01

    Generally, a lead zirconate titanate ceramic is utilized for a high-power transducer such as an ultrasonic motor drive. However, it is difficult to realize an ultrasonic motor that can withstand a high temperature, above 500°C. We focused on lithium niobate because it has a high Curie temperature (1210°C) and high quality factor. The electromechanical coupling factor of lithium niobate is large, although the permittivity is one hundred times smaller compared to that of hard-type lead zirconate titanate (PZT)-8. Hence a stacked structure is required to generate high output power. Dimensions of the fabricated actuator were 10 mm square and 18.5 mm long. The number of lithium niobate layers was 18. The calculated force factor of this transducer was 0.28 N/V, a value comparable to that of the bolted Langevin transducer using PZT, though the vibration velocity was saturated at 0.12 m/s. To realize improved transducer performance, we are attempting to fabricate a new transducer that can generate high vibration velocity.

  18. Structural examination of lithium niobate ferroelectric crystals by combining scanning electron microscopy and atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Efremova, P. V.; Ped'ko, B. B.; Kuznecova, Yu. V.

    2016-02-01

    The structure of lithium niobate single crystals is studied by a complex technique that combines scanning electron microscopy and atomic force microscopy. By implementing the piezoresponse force method on an atomic force microscope, the domain structure of lithium niobate crystals, which was not revealed without electron beam irradiation, is visualized

  19. A Novel Inter Core-Cladding Lithium Niobate Thin Film Coated Fiber Modulator/Sensor

    NASA Technical Reports Server (NTRS)

    Jamison, Tracee L.; Komriech, Phillip; Yu, Chung

    2004-01-01

    A fiber modulator/sensor has been fabricated by depositing a lithium niobate sol-gel thin film between the core and cladding of a fiber preform. The preform is then drawn into 125 micron fiber. The proposed design of lithium niobate cylinder fibers can enhance the existing methodology for detecting sound waves under water utilizing the acoustooptic properties of lithium niobate. Upon application of a stress or strain, light propagating inside the core, according to the principle of total internal reflection, escapes, into the cladding because of the photoelastic boundary layer of lithium niobate. Test results of the lithium niobate fiber reveal a reduction in the 1550 nm, 4mW source with applied tension. The source power from an ordinary quartz fiber under the same stress condition remained invariant to applied tension.

  20. Distribution, structures and nonlinear properties of noncentrosymmetric niobates and tantalates

    SciTech Connect

    Korotkov, A.S. . E-mail: antonis_chem@mail.ru; Atuchin, V.V.

    2006-04-15

    The distribution of 117 noncentrosymmetric niobates and tantalates over different crystal systems and types of space formation of Nb, Ta-O polyhedrons have been revealed. The dependence of polyhedron space formation in the crystal lattice of the compound on stoichiometric concentration (SC) of niobium and tantalum is established. Individual Nb, Ta-O octahedrons are found for SC=19-7.5, and chains and layers of the octahedrons appear in the range SC=11.0-5.2. Only frame formations of Nb, Ta-O octahedrons are possible under SC<5.2.

  1. Properties and applications of potassium lithium tantalate niobate

    NASA Astrophysics Data System (ADS)

    Tong, Xiaolin

    1998-06-01

    This thesis describes the physical and photorefractive properties of potassium lithium tantalate niobate (KLTN) single crystal material. The top seeded solution growth method is reviewed. The phase transition temperatures and dielectric properties are related to the compositions of the KLTN crystals. A liquid/solid interface dynamics model is introduced to explain the experimental results which is that hydrogen ion concentration in KLTN crystals can be reduced dramatically by doping copper in the absence of titanium. Dark conductivity of KLTN crystals are contributed by two species when the temperature is in the range of 250 K and 350 K. Two species are hydrogen ions and shallow trapped electrons (holes). These results have been confirmed by direct dc conductivity measurements and holograms fixing experiments. Hydrogen ion has two types of motion in the crystals: O-H vibration and O-H libration. We established a model to describe hydrogen ions motions and hopping in KLTN crystals. The theoretical prediction is in agreement with experimental results. Hologram thermal fixing for optical data storage is discussed. Hydrogen ions are identified as the mobile ion which is responsible for thermal fixing. In ferroelectric phase KLTN crystals, spontaneous polarization of individual microdomains can be aligned throughout the entire crystal by the poling process. Photorefractive space charge fields play a role deploing the microdomains wherever space charge field opposing to spontaneous polarization. This may cause microdomain switching and lead to the generation of index grating. Experimental observation of Barkhausen current jumps is the signature of domain inversion. Holograms thermal fixing in potassium niobate crystals are also investigated. Because potassium niobate crystal has an orthognal structure with space group mm2, 3D polarization dependence of OH bands are observed. A special cut of iron doped potassium niobate crystal was designed to achieve the maximum

  2. Lithium niobate single-crystal and photo-functional device

    DOEpatents

    Gopalan, Venkatraman; Mitchell, Terrence E.; Kitamura, Kenji; Furukawa, Yasunori

    2001-01-01

    Provided are lithium niobate single-crystal that requires a low voltage of not larger than 10 kV/nm for its ferroelectric polarization inversion and of which the polarization can be periodically inverted with accuracy even at such a low voltage, and a photo-functional device comprising the crystal. The crystal has a molar fraction of Li.sub.2 O/(Nb.sub.2 O.sub.5 +Li.sub.2 O) of falling between 0.49 and 0.52. The photo-functional device can convert a laser ray being incident thereon.

  3. Optical investigation of nanophotonic lithium niobate-based optical waveguide

    NASA Astrophysics Data System (ADS)

    Fakhri, Makram A.; Al-Douri, Y.; Hashim, U.; Salim, Evan T.; Prakash, Deo; Verma, K. D.

    2015-10-01

    Lithium niobate (LiNbO3) nanophotonics are prepared on quartz substrate by sol-gel method. They have been deposited with different molarity concentrations and annealed at 500 °C. These samples are characterized and analyzed by scanning electron microscope, atomic force microscopy, X-ray diffraction and ultraviolet-visible. The measured results show an importance of increasing molarity that indicates the structure starts to crystallize to become more regular. The estimated lattice constants, energy gaps and refractive index give good accordance with experimental results. Also, the calculated refractive index and optical dielectric constant are in agreement with experimental data.

  4. Domain wall width of lithium niobate poled during growth

    NASA Astrophysics Data System (ADS)

    Brooks, R.; Townsend, P. D.; Hole, D. E.; Callejo, D.; Bermúdez, V.; Diéguez, E.

    2003-04-01

    Good quality crystals of periodically poled lithium niobate can be generated directly during growth. However, the temperature gradients at the zone boundaries define the width of the regions where the polarity is reversed. Hence, the region influenced the domain transition may be a significant fraction of the overall poling period for material poled during growth. Evidence for the scale of this feature is reported both by chemical etching and by the less common method of ion beam luminescence and the `domain wall' width approximately 1 mum for these analyses. The influence of the reversal region may differ for alternative techniques but the relevance to device design for second harmonic generation is noted.

  5. Polarization behaviour of femtosecond laser written waveguides in lithium niobate

    NASA Astrophysics Data System (ADS)

    Tejerina, M. R.; Biasetti, D. A.; Torchia, G. A.

    2015-09-01

    In this work, we analysed the polarization of guided light in femtosecond laser written waveguides. The studied waveguides were performed with different laser pulse energies in an x-cut lithium niobate crystal. The guided intensities were experimentally measured and compared with numerical simulations reaching a qualitatively good accordance. This comparison allowed a verification of the "mechanical expansion theory" which is useful to compute the refractive index field. Also, information related to the modelling of waveguides generated with different laser pulse energies was obtained. Both of these facts are keys to design and manufacture optical circuits by using this technological approach.

  6. Simulation of damage induced by ion implantation in Lithium Niobate

    NASA Astrophysics Data System (ADS)

    Bianconi, M.; Bentini, G. G.; Chiarini, M.; De Nicola, P.; Montanari, G. B.; Menin, A.; Nubile, A.; Sugliani, S.

    2010-11-01

    A simulation tool has been developed to engineer the damage formation in Lithium Niobate by ion irradiation with any atomic number and energy. Both nuclear and electronic processes were considered and, in particular, the dependence on the ion velocity of the electronic excitation damage efficiency has been taken into account. By using this tool it is possible both to draw damage nomograms, useful to qualitatively foresee the result of a given process, and to perform reliable simulations of the defect depth profiles, as demonstrated by the good agreement with the experimental data available in the literature.

  7. Anodes for alkaline electrolysis

    DOEpatents

    Soloveichik, Grigorii Lev

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  8. Alkaline "Permanent" Paper.

    ERIC Educational Resources Information Center

    Pacey, Antony

    1991-01-01

    Discussion of paper manufacturing processes and their effects on library materials focuses on the promotion of alkaline "permanent" paper, with less acid, by Canadian library preservation specialists. Standards for paper acidity are explained; advantages of alkaline paper are described, including decreased manufacturing costs; and recyclability is…

  9. Alkaline igneous rocks

    SciTech Connect

    Fitton, J.G.; Upton, B.G.J.

    1987-01-01

    In this volume, an international team of scientists provides an up-to-date overview of the nature, origin, and evolution of alkaline magmas. Particular attention is paid to carbonatites, lamprophyres, and lamproites which are rock suites of current interest not recently reviewed elsewhere. Recent work on the classical alkaline provinces of East Africa, South Greenland, and the Kola Peninsula is included together with reviews of other areas of alkaline magmatism in North and South America, East Greenland, Europe, West Africa, and the ocean basins. Other papers discuss the impact of experimental isotopic and geochemical studies of the petrogenesis of alkaline rocks. This book will be of interest to petrologists and geochemists studying alkaline igneous rocks, and to other earth scientists as a reference on the rapidly expanding field of igneous petrology.

  10. Phonon dynamics and inelastic neutron scattering of sodium niobate

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Gupta, M. K.; Mittal, R.; Zbiri, M.; Rols, S.; Schober, H.; Chaplot, S. L.

    2014-05-01

    Sodium niobate (NaNbO3) exhibits an extremely complex sequence of structural phase transitions in the perovskite family and therefore provides an excellent model system for understanding the mechanism of structural phase transitions. We report temperature dependence of inelastic neutron scattering measurements of phonon densities of states in sodium niobate. The measurements are carried out in various crystallographic phases of this material at various temperatures from 300 to 1048 K. The phonon spectra exhibit peaks centered on 19, 37, 51, 70, and 105 meV. Interestingly, the peak near 70 meV shifts significantly towards lower energy with increasing temperature, while the other peaks do not exhibit any appreciable shift. The phonon spectra at 783 K show prominent change and become more diffusive as compared to those at 303 K. In order to better analyze these features, we have performed first-principles lattice dynamics calculations based on the density functional theory. The computed phonon density of states is found to be in good agreement with the experimental data. Based on our calculation we are able to assign the characteristic Raman modes in the antiferroelectric phase, which are due to the folding of the T (ω = 95 cm-1) and Δ (ω = 129 cm-1) points of the cubic Brillouin zone, to the A1g symmetry.

  11. Er + medium energy ion implantation into lithium niobate

    NASA Astrophysics Data System (ADS)

    Svecova, B.; Nekvindova, P.; Mackova, A.; Oswald, J.; Vacik, J.; Grötzschel, R.; Spirkova, J.

    2009-05-01

    Erbium-doped lithium niobate (Er:LiNbO3) is a prospective photonics component, operating at 1.5 μm, which could find its use chiefly as an optical amplifier or waveguide laser. In this study, we have focused on the properties of the optically active Er:LiNbO3 layers, which are fabricated by medium energy ion implantation under various experimental conditions. Erbium ions were implanted at energies of 330 and 500 keV with fluences of 1.0 × 1015, 2.5 × 1015 and 1.0 × 1016 cm-2 into LiNbO3 single-crystalline cuts of various orientations. The as-implanted samples were annealed in air at 350 °C for 5 h. The depth distribution and diffusion profiles of the implanted Er were measured by Rutherford Backscattering Spectroscopy (RBS) using 2 MeV He+ ions. The projected range RP and projected range straggling ΔRP were calculated employing the SRIM code. The damage distribution and structural changes were described using the RBS/channelling method. Changes of the lithium concentration depth distribution were studied by Neutron Depth Profiling (NDP). The photoluminescence spectra of the samples were measured to determine whether the emission was in the desired region of 1.5 μm. The obtained data made it possible to reveal the relations between the structural changes of erbium-implanted lithium niobate and its luminescence properties important for photonics applications.

  12. Design of nanobeam photonic crystal resonators for a silicon-on-lithium-niobate platform

    NASA Astrophysics Data System (ADS)

    Witmer, Jeremy D.; Hill, Jeff T.; Safavi-Naeini, Amir H.

    2016-03-01

    We outline the design for a photonic crystal resonator made in a hybrid Silicon/Lithium Niobate material system. Using the index contrast between silicon and lithium niobate, it is possible to guide and confine photonic resonances in a thin film of silicon bonded on top of lithium niobate. Quality factors greater than $10^6$ at optical wavelength scale mode volumes are achievable. We show that patterning electrodes on such a system can yield an electro-optic coupling rate of 0.6 GHz/V (4 pm/V).

  13. Design of nanobeam photonic crystal resonators for a silicon-on-lithium-niobate platform.

    PubMed

    Witmer, Jeremy D; Hill, Jeff T; Safavi-Naeini, Amir H

    2016-03-21

    We outline the design for a photonic crystal resonator made in a hybrid Silicon/Lithium Niobate material system. Using the index contrast between silicon and lithium niobate, it is possible to guide and confine photonic resonances in a thin film of silicon bonded on top of lithium niobate. Quality factors greater than 106 at optical wavelength scale mode volumes are achievable. We show that patterning electrodes on such a system can yield an electro-optic coupling rate of 0.6 GHz/V (4 pm/V). PMID:27136784

  14. Structural Investigation of Layered Niobates by DFT Calculations

    NASA Astrophysics Data System (ADS)

    Adhikari Subin, Jhashanath

    Layered forms of inorganic niobates have been used for various applications, such as charge transport and storage, photo-catalysis, solid acids, magnetic materials, superconductors, magneto-resistors and photo-luminescence devices. The layered niobates exists in different geometrical forms and composition with variation in the packing of oxide lattice by the constituting monovalent, divalent/trivalent and pentavalent cations. Four different types of lamellar niobates are studied in this research by theoretical methods, namely the all-electron full-potential DFT method using plane wave and periodic boundary conditions. A common feature of all the layered niobates is that the basic building block, NbO6 octahedral units are shared with each other at the corners and edges forming a covalent network and that the sharing is terminated in a particular direction. These octahedral units get modulated along with the geometry of interlayer interface with the change in the composition of the material. The macroscopic structure change is reflected by the alteration of the unit cell axes whereas the local change at various sites in the structure is revealed by the variation of the atomic distances and angles/tilt. The different properties of the layered compounds are a function of these structural variations and thus understanding the mechanism and the characteristics requires atomic level analysis. Calculations reveal the local bonding details and the bulk geometry of a material and can be compared to that obtained from powder diffraction methods. The EFG tensor which is a sensitive probe of the electronic environment around a quadrupolar nucleus can be used to monitor the minor changes in the bond lengths and angles in various structures. Among the configurations lying in the minima of the potential energy surfaces, the one representing the real material would be the one matching with the EFG tensor calculated from DFT methods with that determined from the SSNMR experiments

  15. Alkaline battery operational methodology

    DOEpatents

    Sholklapper, Tal; Gallaway, Joshua; Steingart, Daniel; Ingale, Nilesh; Nyce, Michael

    2016-08-16

    Methods of using specific operational charge and discharge parameters to extend the life of alkaline batteries are disclosed. The methods can be used with any commercial primary or secondary alkaline battery, as well as with newer alkaline battery designs, including batteries with flowing electrolyte. The methods include cycling batteries within a narrow operating voltage window, with minimum and maximum cut-off voltages that are set based on battery characteristics and environmental conditions. The narrow voltage window decreases available capacity but allows the batteries to be cycled for hundreds or thousands of times.

  16. Novel intercore-cladding lithium niobate thin film coated MOEMS fiber sensor/modulator

    NASA Technical Reports Server (NTRS)

    Jamlson, Tracee L.; Konreich, Phillip; Yu, Chung

    2005-01-01

    A MOEMS fiber modulator/sensor is fabricated by depositing a lithium niobate sol-gel thin film between the core and cladding of a fiber preform. The preform is then drawn into 125-micron fibers. Such a MOEMS modulator design is expected to enhance existing lithium niobate undersea acousto-optic sound wave detectors. In our proposed version, the lithium niobate thin film alters the ordinary silica core/cladding boundary conditions such that, when a stress or strain is applied to the fiber, the core light confinement factor changes, leading to modulation of fiber light transmission. Test results of the lithium niobate embedded fiber with a 1550-nm, 4-mW laser source revealed a reduction in light transmission with applied tension. As a comparison, using the same laser source, an ordinary silica core/cladding fiber did not exhibit any reduction in transmitted light when the same strain was applied. Further experimental work and theoretical analysis is ongoing.

  17. Low loss ridge waveguides in lithium niobate thin films by optical grade diamond blade dicing.

    PubMed

    Volk, Martin F; Suntsov, Sergiy; Rüter, Christian E; Kip, Detlef

    2016-01-25

    We report on the fabrication and characterization of ridge waveguides in lithium niobate thin films by diamond blade dicing. The lithium niobate thin films with a thickness of 1 µm were fabricated by bonding a He-implanted lithium niobate wafer to a SiO(2)-coated lithium niobate wafer and crystal ion slicing. Propagation losses of 1.2 dB/cm for TE and 2.8 dB/cm for TM polarization were measured at 1550 nm for a 9.28 mm long and 2.1 µm wide waveguide using the Fabry-Perot method. PMID:26832519

  18. Spectral separation of Cr3+ optical centers in stoichiometric magnesium-doped lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Galutskii, V. V.; Stroganova, E. V.; Yakovenko, N. A.

    2011-03-01

    The broadband luminescence of chromium optical centers with strongly overlapping spectral lines and similar emission probabilities from excited 4 T 2 states of red and green Cr3+ centers in stoichiometric magnesium-doped lithium niobate crystals has been separated for the first time. The spectral-luminescence characteristics and parameters of intracenter interaction between red and green optical Cr3+ centers in stoichiometric lithium niobate have been calculated. The luminescence quantum efficiencies of red and green chromium centers are determined.

  19. Ultraviolet nanosecond laser-assisted micro-modifications in lithium niobate monitored by Nd3+ luminescence

    NASA Astrophysics Data System (ADS)

    Ródenas, A.; Jaque, D.; Molpeceres, C.; Lauzurica, S.; Ocaña, J. L.; Torchia, G. A.; Agulló-Rueda, F.

    2007-04-01

    This work reports on the microstructural modifications produced by nanosecond ultraviolet ablation in neodymium doped lithium niobate crystals. The neodymium ions have been used as optical probes to determine the extension and nature of the modified bulk material. From micro-luminescence experiments we have been able to determine the spatial distribution of the UV ablation induced material densification, local disorder and defect creation. Results have been compared to those previously obtained from femtosecond irradiated lithium niobate crystals.

  20. Micro- and nanostructures in lithium niobate single crystals doped with lanthanides

    SciTech Connect

    Palatnikov, M. N. Shcherbina, O. B.; Sidorov, N. V.; Bormanis, K.

    2010-09-15

    Lithium niobate single crystals doped with lanthanides (Gd, Er) and nominally pure single crystals of congruent and stoichiometric compositions have been grown under time-dependent thermal conditions. Regular growth domain microstructures and periodic nanostructures have been investigated by optical microscopy and atomic force microscopy with a step from 10 to 100 nm. Comparative investigations of the Raman spectra of lithium niobate single crystals of different compositions have been performed.

  1. Holographic surface gratings in iron-doped lithium niobate

    SciTech Connect

    Sarkisov, S. S.; Curley, M. J.; Kukhtarev, N. V.; Fields, A.; Adamovsky, G.; Smith, C. C.; Moore, L. E.

    2001-08-13

    Surface gratings associated with holographic volume gratings in photorefractive crystals of iron-doped lithium niobate have been studied using diffraction of a reflected probe beam and high-resolution phase-shifted interferometric profilometry. Both techniques show that the surface gratings exist in the form of periodical corrugations of the same period as that of the volume grating. The maximum amplitude of the periodical surface relief measured by both techniques is close to 6.5 nm. We also demonstrated that the periodical electric forces on the surface were capable of assembling polystyrene microspheres along the fringes of the grating. Large amplitude of the periodic electric field (1.6 x 10{sup 4}V/cm) is associated with the photogalvanic effect. {copyright} 2001 American Institute of Physics.

  2. Integrated optic beam combiners in lithium niobate for stellar interferometer

    NASA Astrophysics Data System (ADS)

    Li, Guangyu; Eckhause, Tobias; Winick, Kim A.; Monnier, John D.; Berger, Jean-Philippe

    2006-06-01

    Integrated optics can provide compact and robust solutions for ground and space-based interferometry by integrating optical devices with different functionalities, such as spatial filters, combiners/nullers, and phase modulators, on a single chip. Lithium niobate (LiNbO 3) has two distinct advantages over silica-based technologies, including good transparency further into the near-infrared (covering J, H, K, and L bands) and the ability to support electrically-controlled phase modulation through the linear electro-optic (EO) effect. The design, fabrication and preliminary tests of integrated optic components on LiNbO 3 substrates for astronomical beam combiners operating in the H and L bands is reported. The components include single-mode waveguides of sufficient length for spatial filtering, symmetric junctions for wavelength insensitive power splitters/combiners, and electro-optic waveguide modulators for path-length control.

  3. Investigation of properties of lithium niobate crystals in confined geometries

    NASA Astrophysics Data System (ADS)

    Veenhuizen, Keith; Stone, Greg; Knabe, Bastian; McAnany, Sean; Buse, Karsten; Jain, Himanshu; Dierolf, Volkmar

    The properties of ferroelectric materials in confined geometries, specifically lithium niobate nanocrystals and crystal lines in glass, were studied. Batches of LiNbO3 nanocrystals have been synthesized from various initial ratios of lithium to niobium using the sol-gel method. The batches were analyzed via Raman spectroscopy and SEM imaging to gain information about their size, morphology, stoichiometry, and defect content. The nanocrystals are very sensitive to the initial stoichiometric ratio in the synthesis step. Raman spectra reveal the resultant nanocrystal stoichiometry depends on the initial stoichiometry of the batch, the spectra also reveal an extra phase is present besides LiNbO3 in some batches, and high quality spherical nanocrystals can be synthesized at certain initial stoichiometric ratios. In addition, lines of LiNbO3 were crystallized in lithium-niobo-silica glass systems with varying amounts of silica to understand and control the nucleation and crystallization of the crystals in glass.

  4. Photorefractive properties of cobalt-doped strontium barium niobate crystals

    SciTech Connect

    Bogodaev, N V; Ivleva, Lyudmila I; Lykov, P A; Polozkov, N M; Osiko, Vyacheslav V

    1999-05-31

    The two-wave interaction (at {lambda} = 488 nm) in strontium barium niobate crystals doped with cobalt ions (Co:SBN) was studied. The experimental dependences of the gain coefficient on the grating period and of the grating response time on the writing beam intensity were used to calculate the Debye screening length, the diffusion length, the dark conductivity, and the effective concentration of carrier traps for a series of Co:SBN crystals with different dopant concentrations. The crystals were shown to have high coupling coefficients ({Gamma} = 33 cm{sup -1}) and short optical response times ({tau} = 140 ms for I = 1 W cm{sup -2} ). This, in combination with a high photorefractive sensitivity (S = 39 cm{sup 2} J{sup -1} ), determines the efficiency of their use in the storage of optical information and in laser phase conjugation. (nonlinear optical phenomena)

  5. Integrated optics on Lithium Niobate for sensing applications

    NASA Astrophysics Data System (ADS)

    Zaltron, A.; Bettella, G.; Pozza, G.; Zamboni, R.; Ciampolillo, M.; Argiolas, N.; Sada, C.; Kroesen, S.; Esseling, M.; Denz, C.

    2015-05-01

    In micro-analytical chemistry and biology applications, optofluidic technology holds great promise for creating efficient lab-on-chip systems where higher levels of integration of different stages on the same platform is constantly addressed. Therefore, in this work the possibility of integrating opto-microfluidic functionalities in lithium niobate (LiNbO3) crystals is presented. In particular, a T-junction droplet generator is directly engraved in a LiNbO3 substrate by means of laser ablation process and optical waveguides are realized in the same material by exploiting the Titanium in-diffusion approach. The coupling of these two stages as well as the realization of holographic gratings in the same substrate will allow creating new compact optical sensor prototypes, where the optical properties of the droplets constituents can be monitored.

  6. Tailoring entanglement through domain engineering in a lithium niobate waveguide

    PubMed Central

    Ming, Yang; Tan, Ai-Hong; Wu, Zi-Jian; Chen, Zhao-Xian; Xu, Fei; Lu, Yan-Qing

    2014-01-01

    We propose to integrate the electro-optic (EO) tuning function into on-chip domain engineered lithium niobate (LN) waveguide. Due to the versatility of LN, both the spontaneously parametric down conversion (SPDC) and EO interaction could be realized simultaneously. Photon pairs are generated through SPDC, and the formation of entangled state is modulated by EO processes. An EO tunable polarization-entangled photon state is proposed. Orthogonally-polarized and parallel-polarized entanglements of photon pairs are instantly switchable by tuning the applied field. The characteristics of the source are theoretically investigated showing adjustable bandwidths and high entanglement degrees. Moreover, other kinds of reconfigurable entanglement are also achievable based on suitable domain-design. We believe tailoring entanglement based on domain engineering is a very promising solution for next generation function-integrated quantum circuits. PMID:24770555

  7. Laser irradiation in Nd3+ doped strontium barium niobate glass

    NASA Astrophysics Data System (ADS)

    Haro-González, P.; Martín, I. R.; Arbelo-Jorge, E.; González-Pérez, S.; Cáceres, J. M.; Núñez, P.

    2008-07-01

    A local nanocrystalline formation in a neodymium doped strontium barium niobate (SBN) glass has been obtained under argon laser irradiation. The intense emission around 880 nm, originated from the F43/2 (F45/2) thermalized level when the glass structure changes to a glass ceramic structure due to the irradiation of the laser beam, has been studied. The intensities and lifetimes change from this level inside and outside the irradiated area made by the laser excitation. They have been analyzed and demonstrated that the desvitrification process has been successfully achieved. These results confirm that nanocrystals of SBN have been created by the laser action confirming that the transition from glass to glass ceramic has been completed. These results are in agreement with the emission properties of nanocrystals of the bulk glass ceramic sample. The present study also suggests that the SBN nanocrystal has a potential application as temperature detector.

  8. Nonlinear optical properties of calcium barium niobate epitaxial thin films.

    PubMed

    Bancelin, Stéphane; Vigne, Sébastien; Hossain, Nadir; Chaker, Mohammed; Légaré, François

    2016-07-25

    We investigate the potential of epitaxial calcium barium niobate (CBN) thin film grown by pulsed laser deposition for optical frequency conversion. Using second harmonic generation (SHG), we analyze the polarization response of the generated signal to determine the ratios d15 / d32 and d33 / d32 of the three independent components of the second-order nonlinear susceptibility tensor in CBN thin film. In addition, a detailed comparison to the signal intensity obtained in a y-cut quartz allows us to measure the absolute value of these components in CBN thin film: d15 = 5 ± 2 pm / V, d32 = 3.1 ± 0.6 pm / V and d33 = 9 ± 2 pm / V. PMID:27464195

  9. Li Storage of Calcium Niobates for Lithium Ion Batteries.

    PubMed

    Yim, Haena; Yu, Seung-Ho; Yoo, So Yeon; Sung, Yung-Eun; Choi, Ji-Won

    2015-10-01

    New types of niobates negative electrode were studied for using in lithium-ion batteries in order to alternate metallic lithium anodes. The potassium intercalated compound KCa2Nb3O10 and proton intercalated compound HCa2Nb3O10 were studied, and the electrochemical results showed a reversible cyclic voltammetry profile with acceptable discharge capacity. The as-prepared KCa2Nb3O10 negative electrode had a low discharge capacity caused by high overpotential, but the reversible intercalation and deintercalation reaction of lithium ions was activated after exchanging H+ ions for intercalated K+ ions. The initial discharge capacity of HCa2Nb3O10 was 54.2 mAh/g with 92.1% of coulombic efficiency, compared with 10.4 mAh/g with 70.2% of coulombic efficiency for KCa2Nb3O10 at 1 C rate. The improved electrochemical performance of the HCa2Nb3O10 was related to the lower bonding energy between proton cation and perovskite layer, which facilitate Li+ ions intercalating into the cation site, unlike potassium cation and perovskite layer. Also, this negative material can be easily exfoliated to Ca2Nb3O10 layer by using cation exchange process. Then, obtained two-dimensional nanosheets layer, which recently expected to be an advanced electrode material because of its flexibility, chemical stable, and thin film fabricable, can allow Li+ ions to diffuse between the each perovskite layer. Therefore, this new type layered perovskite niobates can be used not only bulk-type lithium ion batteries but also thin film batteries as a negative material. PMID:26726470

  10. Lithium niobate transducers for MRI-guided ultrasonic microsurgery.

    PubMed

    Kotopoulis, Spiros; Wang, Han; Cochran, Sandy; Postema, Michiel

    2011-08-01

    Focused ultrasound surgery (FUS) is usually based on frequencies below 5 MHz-typically around 1 MHz. Although this allows good penetration into tissue, it limits the minimum lesion dimensions that can be achieved. In this study, we investigate devices to allow FUS at much higher frequencies, in principle, reducing the minimum lesion dimensions. Furthermore, FUS can produce deep-sub-millimeter demarcation between viable and necrosed tissue; high-frequency devices may allow this to be exploited in superficial applications which may include dermatology, ophthalmology, treatment of the vascular system, and treatment of early dysplasia in epithelial tissue. In this paper, we explain the methodology we have used to build high-frequency high-intensity transducers using Y-36°-cut lithium niobate. This material was chosen because its low losses give it the potential to allow very-high-frequency operation at harmonics of the fundamental operating frequency. A range of single-element transducers with center frequencies between 6.6 and 20.0 MHz were built and the transducers' efficiency and acoustic power output were measured. A focused 6.6-MHz transducer was built with multiple elements operating together and tested using an ultrasound phantom and MRI scans. It was shown to increase phantom temperature by 32°C in a localized area of 2.5 x 3.4 mm in the plane of the MRI scan. Ex vivo tests on poultry tissue were also performed and shown to create lesions of similar dimensions. This study, therefore, demonstrates that it is feasible to produce high-frequency transducers capable of high-resolution FUS using lithium niobate. PMID:21859576

  11. Alkaline flooding injection strategy

    SciTech Connect

    French, T.R.; Josephson, C.B.

    1992-03-01

    The objective of this project is to improved alkali-surfactant flooding methods, and this includes determining the proper design of injection strategy. Several different injection strategies have been used or suggested for recovering heavy oils with surfactant-enhanced alkaline flooding methods. Oil recovery was compared for four different injection strategies: (1) surfactant followed by polymer, (2) surfactant followed by alkaline polymer, (3) alkaline surfactant followed by polymer, and (4) alkali, surfactant, and polymer mixed in a single formulation. The effect of alkaline preflush was also studied under two different conditions. All of the oil recovery experiments were conducted under optimal conditions with a viscous, non-acidic oil from Hepler (KS) oil field. The coreflood experiments were conducted with Berea sandstone cores since field core was not available in sufficient quantity for coreflood tests. The Tucker sand of Hepler field is a Class I fluvial dominated deltaic reservoir, as classified by the Department of Energy, which has been selected as the site of a DOE-sponsored field pilot test.

  12. Growth, defect structure, and THz application of stoichiometric lithium niobate

    NASA Astrophysics Data System (ADS)

    Lengyel, K.; Péter, Á.; Kovács, L.; Corradi, G.; Pálfalvi, L.; Hebling, J.; Unferdorben, M.; Dravecz, G.; Hajdara, I.; Szaller, Zs.; Polgár, K.

    2015-12-01

    Owing to the extraordinary richness of its physical properties, congruent lithium niobate has attracted multidecade-long interest both for fundamental science and applications. The combination of ferro-, pyro-, and piezoelectric properties with large electro-optic, acousto-optic, and photoelastic coefficients as well as the strong photorefractive and photovoltaic effects offers a great potential for applications in modern optics. To provide powerful optical components in high energy laser applications, tailoring of key material parameters, especially stoichiometry, is required. This paper reviews the state of the art of growing large stoichiometric LiNbO3 (sLN) crystals, in particular, the defect engineering of pure and doped sLN with emphasis on optical damage resistant (ODR) dopants (e.g., Mg, Zn, In, Sc, Hf, Zr, Sn). The discussion is focused on crystals grown by the high temperature top seeded solution growth (HTTSSG) technique using alkali oxide fluxing agents. Based on high-temperature phase equilibria studies of the Li2O-Nb2O5-X2O ternary systems (X = Na, K, Rb, Cs), the impact of alkali homologue additives on the stoichiometry of the lithium niobate phase will be analyzed, together with a summary of the ultraviolet, infrared, and far-infrared absorption spectroscopic methods developed to characterize the composition of the crystals. It will be shown that using HTTSSG from K2O containing flux, crystals closest to the stoichiometric composition can be grown characterized by a UV-edge position of at about 302 nm and a single narrow hydroxyl band in the IR with a linewidth of less than 3 cm-1 at 300 K. The threshold concentrations for ODR dopants depend on crystal stoichiometry and the valence of the dopants; Raman spectra, hydroxyl vibration spectra, and Z-scan measurements prove to be useful to distinguish crystals below and above the photorefractive threshold. Crystals just above the threshold are preferred for most nonlinear optical applications apart

  13. Validity Using Pump-Probe Pulses to Determine the Optical Response of Niobate Crystals

    NASA Technical Reports Server (NTRS)

    Liu, Huimin; Jia, Weiyi

    1997-01-01

    A variety of niobate crystals have found their places in nonlinear optical applications as well as in laser devices. In recent years much attention has been paid to study the ultrafast optical response in a variety of photorefractive crystals such as KTa(1-x)Nb(x)O3 and KNbO3 crystals, glasses, semiconductors and polymers for applications in optical switching, information processing, optical computing, and all-optical device systems. Third-order optical nonlinearity is the most important property for realization of all-optical switching. Therefore experiments have been performed on the third order susceptibility using a variety of techniques such as the third-order harmonic generation, EFISH and degenerate four-wave mixing(DFWM). The latter has been conducted with a variety of pump wavelengths and with nanosecond, picosecond and femtosecond pulses. Niobate crystals, such as potassium niobate KNbO3, potassium tantalate niobate KTN family (KTa(1-x)Nb(x)O3), strontium barium niobate SBN (Sr(x)Ba(1-x)Nb2O6) and potassium-sodium niobate SBN (KNSBN) are attractive due to their photorefractive properties for application in optical storage and processing. The pulsed probe experiments performed on theses materials have suggested two types of time responses. These responses have been associated with an coherent response due to Chi(sup 3), and a long lived component due to excited state population. Recent study of DFWM on KNbO3 and KTN family reveals that the long lived component of those crystals depends on the crystal orientation. A slowly decaying signal is observable when the grating vector K(sub g) is not perpendicular to the C-axis of those photorefractive crystals', otherwise the optical response signal would be only a narrow coherent peak with FWHM equal to the cross-correlation width of the write beam pulses. Based on this understanding, we study the photodynamical process of a variety of niobate crystals using DFWM in a Kg perpindicular to C geometry with a ps

  14. Optical and structural properties of single-crystal lithium niobate thin film

    NASA Astrophysics Data System (ADS)

    Han, Huangpu; Cai, Lutong; Hu, Hui

    2015-04-01

    High-refractive-index contrast, single-crystal lithium niobate thin films are emerging as a new platform for integrated optics. Such lithium niobate thin films are prepared using ion implantation and direct-wafer bonding to a SiO2 layer deposited on a LN substrate. However, the ion-implantation process can cause changes in the refractive index and result in lattice damage, and there are few studies on the optical and structural properties of lithium niobate thin film to compensate for this. In this paper, we reported that the refractive index of lithium niobate thin film can reach that of the bulk material by annealing in an oxygen atmosphere at 500 °C for 5 h. The experimental results of high-resolution X-ray diffraction (HRXRD) and Rutherford back-scattering spectrum (RBS) showed a good crystal lattice arrangement in the LN thin film. These experimental results confirmed that the refractive index and crystal-lattice structural properties of the lithium niobate thin film were similar to that of the bulk material. To demonstrate the application on integrated optics, a 1 μm wide photonic wire was fabricated and the near-field intensity profile at 1.55 μm wavelength was obtained and compared with the simulation result.

  15. Growth and Transverse Field Muon Spin Rotation of Cobalt Niobate

    NASA Astrophysics Data System (ADS)

    Munsie, Timothy; Millington, Anna; Marjerrison, Casey; Medina, Teresa; Wilson, Murray; Kermarrec, Edwin; Liu, Lian; Dabkowska, Hanna; Uemura, Yasutomo; Williams, Travis; Luke, Graeme

    2014-03-01

    Cobalt niobate, CoNb2O6, is a material whose spins, when in a transverse field, act like the theoretical ideal 1D-Ising model. This occurs due to the magnetic spins aligning highly anisotropically along the Co2+ chains. Because of this unique structure and material performance, the creation and characterization of this material is of both experimental and theoretical interest. The research we will present is a detailing of changes in the characteristics of the growth of the material utilizing the optical floating zone crystal growth method compared to previous growth parameters and an examination of this material in a moderately high transverse field using the technique of muon spin rotation (μSR). We have determined that the quality of crystals created by the floating zone are highly dependent on the growth parameters utilized (original ceramic shape and rotation rate) and dictate the speed at which the growth can be performed. Transverse Field μSR shows a gradual but significant change to the magnetic structure of the material below 5 K. Second Affiliation: Brockhouse Institute for Materials Research.

  16. Photoluminescence of Erbium-Doped Potassium Tantalate Niobate Polycrystalline

    NASA Astrophysics Data System (ADS)

    Wen, Cheng‑Hung; Chu, Sheng‑Yuan; Shin, Yan‑Yu; Wen, Cheng‑Kuo

    2006-07-01

    In this study, we investigated the luminescence properties of erbium-doped potassium tantalite niobate (KTaxNb1-xO3 or KTN) ceramics, which were prepared by the conventional solid-state reaction synthesis method. In this work, we studied the relationships of the crystal structure, and Raman and photoluminescence (PL) spectra with the tantalum concentration, respectively. The experiments showed that the tantalum dopants modified the intensity of the green, red and near-infrared emission bands. The experiments also showed a blue shift for the 2 mol % erbium doped KTN samples with different tantalum compositions. Doping Ta not only led to the change in PL intensity but also in spectral shapes. The PL spectra showed the splitting peaks for the samples with low Ta compositions. Then these peaks combined and broadened as Ta concentration increase. When Ta was substituted for Nb completely, the luminescence intensity of the green emission band had an increase of approximately about one order of magnitude, which was because of the absence of the first-order phonon relaxation in the high-Ta-concentration samples.

  17. Diamond micro-milling of lithium niobate for sensing applications

    NASA Astrophysics Data System (ADS)

    Huo, Dehong; Jie Choong, Zi; Shi, Yilun; Hedley, John; Zhao, Yan

    2016-09-01

    Lithium niobate (LiNbO3) is a crystalline material which is widely applied in surface acoustic wave, microelectromechanical systems (MEMS), and optical devices, owing to its superior physical, optical, and electronic properties. Due to its low toughness and chemical inactivity, LiNbO3 is considered to be a hard-to-machine material and has been traditionally left as as an inert substrate upon which other micro structures are deposited. However, in order to make use of its superior material properties and increase efficiency, the fabrication of microstructures directly on LiNbO3 is in high demand. This paper presents an experimental investigation on the micro machinability of LiNbO3 via micro milling with the aim of obtaining optimal process parameters. Machining of micro slots was performed on Z-cut LiNbO3 wafers using single crystal diamond tools. Surface and edge quality, cutting forces, and the crystallographic effect were examined and characterized. Ductile mode machining of LiNbO3 was found to be feasible at a low feed rate and small depth of cut. A strong crystallographic effect on the machined surface quality was also observed. Finally, some LiNbO3 micro components applicable to sensing applications were fabricated.

  18. The OH - absorption spectra of low doped lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Kong, Yongfa; Zhang, Wanlin; Xu, Jingjun; Yan, Wenbo; Liu, Hongde; Xie, Xiang; Li, Xiaochun; Shi, Lihong; Zhang, Guangyin

    2004-07-01

    The OH - absorption spectra of low doped lithium niobate (LiNbO 3) crystals have been investigated. Though no apparent band shift is observed in these absorption spectra, their shapes are quite different. In order to analyze the information on the defect structure underlying these OH - absorption bands, the normalization and difference methods were employed. It was found that although the doping concentrations are under the thresholds the doping ions have apparent affect to the site occupation of OH - ions. The OH - vibrations related to Mg Li+ (Mg 2+ occupying Li-site) and In Li2+ are 3483 and 3484 cm -1 in LiNbO 3:Mg and LiNbO 3:In crystals, respectively. The absorption peak of LiNbO 3:Ti (2.5 mol%) crystal at 3487 cm -1 is mainly related to Ti Li3+-OH - and the 3489 cm -1 peak of LiNbO 3:Mg (5.0 mol%), Ti (10.0 mol%) related to Mg Li+-OH -, Ti Nb--OH - and Ti Li3+-OH -. Doping with Na improves the peak intensity near 3466 cm -1 and induces a new absorption peak at 3470 cm -1. The absorption bands of LiNbO 3 crystals codoped with trivalent ions are associated with the co-effect of the doped ions and have some different characteristics from mono-doped crystals.

  19. Hydrothermal Synthesis and Dielectric Properties of Lead Nickel Niobate Ceramics

    NASA Astrophysics Data System (ADS)

    Lu, Chung-Hsin; Hwang, Wen-Jeng

    1999-09-01

    Lead nickel niobate (Pb(Ni1/3Nb2/3)O3) has been prepared by a newly developed hydrothermal process. During the hydrothermal reaction at 250°C, a pyrochlore phase is formed. After calcining the 250°C-hydrothermally derived precursors at 750°C, a monophasic Pb(Ni1/3Nb2/3)O3 compound is successfully produced. Increasing the hydrothermal temperature significantly facilitates the formation of the perovskite phase. In comparison with the solid-state reaction, the hydrothermal process not only reduces the temperature for synthesizing Pb(Ni1/3Nb2/3)O3, but also decreases its particle size to the submicron range. The dielectric properties of Pb(Ni1/3Nb2/3)O3 strongly depend on the electric field frequency. Increasing the field frequency results in an increase in the apparent Curie temperature, which is associated with a decrease in the maximum dielectric permittivity. The critical exponent and diffuseness calculated by a modified permittivity-temperature equation verify the relaxor characteristics of Pb(Ni1/3Nb2/3)O3.

  20. New, dense, and fast scintillators based on rare-earth tantalo-niobates

    NASA Astrophysics Data System (ADS)

    Voloshyna, O. V.; Boiaryntseva, I. A.; Baumer, V. N.; Ivanov, A. I.; Korjik, M. V.; Sidletskiy, O. Ts.

    2014-11-01

    Samples of undoped yttrium and gadolinium tantalo-niobates with common formulae RE(NbxTa1-x)O4, where RE=Y or Gd and x=0-1, have been obtained by solid-state reaction. Systematic study of structural, luminescent, and scintillation properties of these compounds was carried out. Lattice parameters and space groups of the mixed compounds were identified. UV- and X-ray luminescence spectra, as well as relative light outputs and scintillation decay times are measured. Gadolinium tantalo-niobate with the formulae GdNb0.2Ta0.8O4 showed the light output around 13 times larger than PbWO4 and fast decay with time constant 12 ns without additional slow component. Gadolinium tantalo-niobates may be considered as promising materials for high energy physics due to extremely high density, substantial light output, and fast decay.

  1. New synthesis of nanosized niobium oxides and lithium niobate particles and their characterization by XPS analysis.

    PubMed

    Aufray, Maëlenn; Menuel, Stéphane; Fort, Yves; Eschbach, Julien; Rouxel, Didier; Vincent, Brice

    2009-08-01

    This work presents a new synthesis of nano-sized lithium niobate particles by a low temperature three steps procedure. The complete protocol implies a LiH induced reduction of NbCl5 followed by in situ spontaneous oxidation into low valence niobium nano-oxides. These niobium oxides are exposed to air atmosphere leading to pure Nb2O5 formation. Finally, the stable Nb2O5 is converted into lithium niobate LiNbO3 nanoparticles during the controlled hydrolysis of the LiH excess. The nano-sized lithium niobate particles as well as their formation processes were characterized using X-ray photoelectron spectroscopy. PMID:19928149

  2. Alkaline quinone flow battery.

    PubMed

    Lin, Kaixiang; Chen, Qing; Gerhardt, Michael R; Tong, Liuchuan; Kim, Sang Bok; Eisenach, Louise; Valle, Alvaro W; Hardee, David; Gordon, Roy G; Aziz, Michael J; Marshak, Michael P

    2015-09-25

    Storage of photovoltaic and wind electricity in batteries could solve the mismatch problem between the intermittent supply of these renewable resources and variable demand. Flow batteries permit more economical long-duration discharge than solid-electrode batteries by using liquid electrolytes stored outside of the battery. We report an alkaline flow battery based on redox-active organic molecules that are composed entirely of Earth-abundant elements and are nontoxic, nonflammable, and safe for use in residential and commercial environments. The battery operates efficiently with high power density near room temperature. These results demonstrate the stability and performance of redox-active organic molecules in alkaline flow batteries, potentially enabling cost-effective stationary storage of renewable energy. PMID:26404834

  3. Optical spectroscopy of trivalent chromium in sol-gel lithium niobate

    SciTech Connect

    Krebs, J.K.; Happek, U.

    2005-12-19

    We report on the characterization of sol-gel derived lithium niobate via trivalent chromium probe ions, a study that is motivated by recent reports on the synthesis of high quality sol-gel lithium niobate (LiNbO{sub 3}). In order to assess the quality of sol-gel derived LiNbO{sub 3}, we incorporate Cr{sup 3+} during the hydrolysis stage of the sol-gel process. A comparison of the Cr{sup 3+} emission and photoexcitation data on both sol-gel and melt-grown LiNbO{sub 3} shows that the sol-gel derived material is highly stoichiometric.

  4. Self-trapping of low-energy infrared femtosecond beams in lithium niobate

    SciTech Connect

    Pettazzi, Federico; Alonzo, Massimo; Centini, Marco; Fazio, Eugenio; Petris, Adrian; Vlad, Valentin I.; Chauvet, Mathieu

    2007-12-15

    In this paper we report self-trapping of subnanojoule femtosecond near-infrared beams in photonic-grade undoped bulk lithium niobate under application of an external dc electric field. We show that the phenomenon occurs thanks to the photorefractive effect induced by a weak second-harmonic component generated under large velocity mismatch. It offers a way to extend lithium niobate's photorefractive response to the near-infrared spectrum for peak intensity lower than 1 GW/cm{sup 2}, which is three orders of magnitude lower than reported in the literature.

  5. Calcium barium niobate as a functional material for broadband optical frequency conversion.

    PubMed

    Sheng, Yan; Chen, Xin; Lukasiewicz, Tadeusz; Swirkowicz, Marek; Koynov, Kaloian; Krolikowski, Wieslaw

    2014-03-15

    We demonstrate the application of as-grown calcium barium niobate (CBN) crystal with random-sized ferroelectric domains as a broadband frequency converter. The frequency conversion process is similar to broadband harmonic generation in commonly used strontium barium niobate (SBN) crystal, but results in higher conversion efficiency reflecting a larger effective nonlinear coefficient of the CBN crystal. We also analyzed the polarization properties of the emitted radiation and determined the ratio of d32 and d33 components of the second-order susceptibility tensor of the CBN crystal. PMID:24690779

  6. Enhancing second harmonic generation in gold nanoring resonators filled with lithium niobate.

    PubMed

    Lehr, Dennis; Reinhold, Jörg; Thiele, Illia; Hartung, Holger; Dietrich, Kay; Menzel, Christoph; Pertsch, Thomas; Kley, Ernst-B; Tünnermann, Andreas

    2015-02-11

    Plasmonic nanorings provide the unique advantage of a pronounced plasmonic field enhancement inside their core. If filled with a polarizable medium, it may significantly enhance its optical effects. Here, we demonstrate this proposition by filling gold nanorings with lithium niobate. The generated second harmonic signal is compared to the signal originating from an unpatterned lithium niobate surface. Measurements and simulation confirm an enhancement of about 20. Applications requiring nanoscopic localized light sources like fluorescence spectroscopy or quantum communication will benefit from our findings. PMID:25584636

  7. Lattice vibrations and phase-transition soft mode in near stoichiometric lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Xia, H. R.; Sun, S. Q.; Cheng, X. F.; Dong, S. M.; Xu, H. Y.; Gao, L.; Cui, D. L.

    2005-08-01

    At room temperature, Raman-scattering investigations of near stoichiometric lithium niobate (S-LN) crystals theoretically and experimentally reveal an effect of the lattice vacant positions on the Raman spectra. At high temperature, Raman peaks of the mode ν5 vary sensitively and intensely with the increase of the temperature. A condensed soft optical-phonon mode originates from the triply degenerate symmetric in-plane O-Nb-O bending. The paraelectric-ferroelectric structural transition occurs at about 1170°C. The composition homogeneity and optical uniformity of the S-LN crystals are demonstrated to be excellent compared with those of the congruent lithium niobate.

  8. Erbium ion implantation into different crystallographic cuts of lithium niobate

    NASA Astrophysics Data System (ADS)

    Nekvindova, P.; Svecova, B.; Cajzl, J.; Mackova, A.; Malinsky, P.; Oswald, J.; Kolistsch, A.; Spirkova, J.

    2012-02-01

    Single crystals like lithium niobate are frequently doped with optically active rare-earth or transition-metal ions for a variety of applications in optical devices such as solid-state lasers, amplifiers or sensors. To exploit the potential of the Er:LiNbO 3, one must ensure high intensity of the 1.5 μm luminescence as an inevitable prerequisite. One of the important factors influencing the luminescence properties of a lasing ion is the crystal field of the surrounding, which is inevitably determined by the crystal structure of the pertinent material. From that point it is clear that it cannot be easy to affect the resulting luminescence properties - intensity or position of the luminescence band - without changing the structure of the substrate. However, there is a possibility to utilise a potential of the ion implantation of the lasing ions, optionally accompanied with a sensitising one, that can, besides the doping, also modify the structure of the treated area od the crystal. This effect can be eventually enhanced by a post-implantation annealing that may help to recover the damaged structure and hence to improve the desired luminescence. In this paper we are going to report on our experiments with ion-implantation technique followed with subsequent annealing could be a useful way to influence the crystal field of LN. Optically active Er:LiNbO 3 layers were fabricated by medium energy implantation under various experimental conditions. The Er + ions were implanted at energies of 330 and 500 keV with fluences ranging from 1.0 × 10 15 to 1.0 × 10 16 ion cm -2 into LiNbO 3 single-crystal cuts of both common and special orientations. The as-implanted samples were annealed in air and oxygen at two different temperatures (350 and 600 °C) for 5 h. The depth concentration profiles of the implanted erbium were measured by Rutherford Backscattering Spectroscopy (RBS) using 2 MeV He + ions. The photoluminescence spectra of the samples were measured to determine the

  9. Growth, defect structure, and THz application of stoichiometric lithium niobate

    SciTech Connect

    Lengyel, K.; Péter, Á.; Kovács, L.; Corradi, G.; Dravecz, G.; Hajdara, I.; Szaller, Zs.; Polgár, K.; Pálfalvi, L.; Unferdorben, M.; Hebling, J.

    2015-12-15

    Owing to the extraordinary richness of its physical properties, congruent lithium niobate has attracted multidecade-long interest both for fundamental science and applications. The combination of ferro-, pyro-, and piezoelectric properties with large electro-optic, acousto-optic, and photoelastic coefficients as well as the strong photorefractive and photovoltaic effects offers a great potential for applications in modern optics. To provide powerful optical components in high energy laser applications, tailoring of key material parameters, especially stoichiometry, is required. This paper reviews the state of the art of growing large stoichiometric LiNbO{sub 3} (sLN) crystals, in particular, the defect engineering of pure and doped sLN with emphasis on optical damage resistant (ODR) dopants (e.g., Mg, Zn, In, Sc, Hf, Zr, Sn). The discussion is focused on crystals grown by the high temperature top seeded solution growth (HTTSSG) technique using alkali oxide fluxing agents. Based on high-temperature phase equilibria studies of the Li{sub 2}O–Nb{sub 2}O{sub 5}–X{sub 2}O ternary systems (X = Na, K, Rb, Cs), the impact of alkali homologue additives on the stoichiometry of the lithium niobate phase will be analyzed, together with a summary of the ultraviolet, infrared, and far-infrared absorption spectroscopic methods developed to characterize the composition of the crystals. It will be shown that using HTTSSG from K{sub 2}O containing flux, crystals closest to the stoichiometric composition can be grown characterized by a UV-edge position of at about 302 nm and a single narrow hydroxyl band in the IR with a linewidth of less than 3 cm{sup −1} at 300 K. The threshold concentrations for ODR dopants depend on crystal stoichiometry and the valence of the dopants; Raman spectra, hydroxyl vibration spectra, and Z-scan measurements prove to be useful to distinguish crystals below and above the photorefractive threshold. Crystals just above the threshold are

  10. Lightning arrestor connector lead magnesium niobate qualification pellet test procedures.

    SciTech Connect

    Tuohig, W.; Mahoney, Patrick A.; Tuttle, Bruce Andrew; Wheeler, Jill Susanne

    2009-02-01

    Enhanced knowledge preservation for DOE DP technical component activities has recently received much attention. As part of this recent knowledge preservation effort, improved documentation of the sample preparation and electrical testing procedures for lead magnesium niobate--lead titanate (PMN/PT) qualification pellets was completed. The qualification pellets are fabricated from the same parent powders used to produce PMN/PT lightning arrestor connector (LAC) granules at HWF&T. In our report, the procedures for fired pellet surface preparation, electrode deposition, electrical testing and data recording are described. The dielectric measurements described in our report are an information only test. Technical reasons for selecting the electrode material, electrode size and geometry are presented. The electrical testing is based on measuring the dielectric constant and dissipation factor of the pellet during cooling from 280 C to 220 C. The most important data are the temperature for which the peak dielectric constant occurs (Curie Point temperature) and the peak dielectric constant magnitude. We determined that the peak dielectric constant for our procedure would be that measured at 1 kHz at the Curie Point. Both the peak dielectric constant and the Curie point parameters provide semi-quantitative information concerning the chemical and microstructural homogeneity of the parent material used for the production of PMN/PT granules for LACs. Finally, we have proposed flag limits for the dielectric data for the pellets. Specifically, if the temperature of the peak dielectric constant falls outside the range of 250 C {+-} 30 C we propose that a flag limit be imposed that will initiate communication between production agency and design agency personnel. If the peak dielectric constant measured falls outside the range 25,000 {+-} 10,000 we also propose that a flag limit be imposed.

  11. Lithium niobate-on-insulator (LNOI): status and perspectives

    NASA Astrophysics Data System (ADS)

    Hu, Hui; Yang, Jin; Gui, Li; Sohler, Wolfgang

    2012-06-01

    As optical components continue to replace electronics in ultrafast signal processing applications, a growing interest in further miniaturization and integration of photonic devices on a single chip is observed. Therefore, optical waveguides of high refractive index contrast of core and cladding materials are developed since a couple of years. They can have a very small cross section and also bending radius, enabling the development of ultra-compact photonic integrated devices and circuits. Silicon-On-Insulator (SOI) waveguides ("photonic wires") and devices are the most prominent examples. A corresponding technology for Lithium Niobate-On-Insulator (LNOI) waveguides is still in its infancy, though LN offers - in contrast to SOI - excellent electro-optic, acousto-optic, and nonlinear optical properties. Moreover, it can be easily doped with rare-earth ions to get a laser active material. Therefore, LNOI photonic wires will enable the development of a wide range of extremely compact, active integrated devices, including electro-optical modulators, tunable filters, nonlinear (periodically poled) wavelength converters, and amplifiers and lasers of different types. The state-of-the-art of LNOI films as platform for high-density integrated optics is reviewed. Using a full-wafer technology (3" diameter), sub-micrometer thin LN films are obtained by high-dose He+ ion implantations, crystal-bonding to a low-index substrate (preferably SiO2) and cleaving by a special annealing step ("ion-beam-slicing"). Various LNOI structures, also combined with metallic layers, are presented. Based on such platforms, photonic wires and micro-photonic devices are developed using different micro- and nano-structuring techniques. To be specific, the fabrication and characterization of LNOI photonic wires with cross-section < 1 μm2, and periodically poled LNOI photonic wires for second harmonic generation are reported in detail.

  12. Ridge Waveguide Structures in Magnesium-Doped Lithium Niobate

    NASA Technical Reports Server (NTRS)

    Himmer, Phillip; Battle, Philip; Suckow, William; Switzer, Greg

    2011-01-01

    This work proposes to establish the feasibility of fabricating isolated ridge waveguides in 5% MgO:LN. Ridge waveguides in MgO:LN will significantly improve power handling and conversion efficiency, increase photonic component integration, and be well suited to spacebased applications. The key innovation in this effort is to combine recently available large, high-photorefractive-damage-threshold, z-cut 5% MgO:LN with novel ridge fabrication techniques to achieve high-optical power, low-cost, high-volume manufacturing of frequency conversion structures. The proposed ridge waveguide structure should maintain the characteristics of the periodically poled bulk substrate, allowing for the efficient frequency conversion typical of waveguides and the high optical damage threshold and long lifetimes typical of the 5% doped bulk substrate. The low cost and large area of 5% MgO:LN wafers, and the improved performance of the proposed ridge waveguide structure, will enhance existing measurement capabilities as well as reduce the resources required to achieve high-performance specifications. The purpose of the ridge waveguides in MgO:LN is to provide platform technology that will improve optical power handling and conversion efficiency compared to existing waveguide technology. The proposed ridge waveguide is produced using standard microfabrication techniques. The approach is enabled by recent advances in inductively coupled plasma etchers and chemical mechanical planarization techniques. In conjunction with wafer bonding, this fabrication methodology can be used to create arbitrarily shaped waveguides allowing complex optical circuits to be engineered in nonlinear optical materials such as magnesium doped lithium niobate. Researchers here have identified NLO (nonlinear optical) ridge waveguide structures as having suitable value to be the leading frequency conversion structures. Its value is based on having the low-cost fabrication necessary to satisfy the challenging pricing

  13. Emerging cool white light emission from Dy(3+) doped single phase alkaline earth niobate phosphors for indoor lighting applications.

    PubMed

    Vishwakarma, Amit K; Jha, Kaushal; Jayasimhadri, M; Sivaiah, B; Gahtori, Bhasker; Haranath, D

    2015-10-21

    Single-phase cool white-light emitting BaNb2O6:Dy(3+) phosphors have been synthesized via a conventional solid-state reaction method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) observations and spectrofluorophotometric measurements. XRD and Rietveld structural refinement studies confirm that all the samples exhibit pure orthorhombic structure [space group -C2221(20)]. SEM observations reveal the dense particle packaging with irregular morphology in a micron range. The as-prepared phosphors exhibit blue (482 nm) and yellow (574 nm) emissions under 349, 364, 386 and 399 nm excitations corresponding to (4)F9/2→(6)HJ (J = 15/2, 13/2) transitions of Dy(3+) ions. The energy transfer mechanism between Dy(3+) ions has been studied in detail and the luminescence decay lifetime for the (4)F9/2 level was found to be around 146.07 μs for the optimized phosphor composition. The calculated Commission Internationale de L'Eclairage (CIE) chromaticity coordinates for the optimized phosphor are (x = 0.322, y = 0.339), which are close to the National Television Standard Committee (NTSC) (x = 0.310, y = 0.316) coordinates. The values of CIE chromaticity coordinates and correlated color temperature (CCT) of 5907 K endorse cool white-light emission from the phosphor. The study reveals that BaNb2O6:Dy(3+) phosphor could be a potential candidate for near ultra-violet (NUV) excited white-LED applications. PMID:26374377

  14. Generation of high spectral purity photon-pairs with MgO-doped periodically poled lithium niobate

    NASA Astrophysics Data System (ADS)

    Zhan, Mengying; Sun, Qichao; Xiang, Tong; Chen, Xianfeng

    2015-12-01

    We study the spectral correlation of photon pairs generated via type-II spontaneous parametric down conversion in periodically poled lithium niobate crystals. By performing Schmidt decomposition on the two-photon wavefunction, we calculate the spectral purity of the two-photon state under various pump laser characteristics and doping concentrations of MgO in lithium niobate crystals. Our results show that periodically poled 5% MgO doped lithium niobate is a good candidate to generate photon-pairs with high spectral purity at telecom wavelength.

  15. Surface acoustic wave generation and detection using graphene interdigitated transducers on lithium niobate

    SciTech Connect

    Mayorov, A. S.; Hunter, N.; Muchenje, W.; Wood, C. D.; Rosamond, M.; Linfield, E. H.; Davies, A. G.; Cunningham, J. E.

    2014-02-24

    We demonstrate the feasibility of using graphene as a conductive electrode for the generation and detection of surface acoustic waves at 100 s of MHz on a lithium niobate substrate. The graphene interdigitated transducers (IDTs) show sensitivity to doping and temperature, and the characteristics of the IDTs are discussed in the context of a lossy transmission line model.

  16. Investigation of enhanced forward and backward anti-stokes Raman signals in lithium niobate waveguides

    SciTech Connect

    Li, Da; Hong, Pengda; Ding, Yujie J.; Liu, Zhaojun; Wang, Lei; Hua, Ping-Rang; Zhang, De-Long

    2015-07-07

    We have observed enhancements of the anti-Stokes Raman signals generated in lithium niobate waveguides in the forward and backward configurations by at least one order of magnitude under the pump power of the microwatt level. These output signals were measured using a single photon detector. The forward and backward propagating anti-Stokes signals exhibited different spectral features.

  17. Optical planar waveguide in sodium-doped calcium barium niobate crystals by carbon ion implantation

    NASA Astrophysics Data System (ADS)

    Zhao, Jin-Hua; Qin, Xi-Feng; Wang, Feng-Xiang; Fu, Gang; Wang, Hui-Lin; Wang, Xue-Lin

    2013-07-01

    There is great interest in niobate crystals which belong to the tetragonal tungsten bronze (TTB) families owing to their intriguing properties. As one representative of such crystals, CBN (calcium barium niobate) has attracted rapidly growing attention. Because it has a higher Curie temperature than SBN (strontium barium niobate), possesses outstanding ferroelectric and it possesses optical properties. In addition, doped with sodium, CBN will show a higher Curie temperature than pure CBN. We report on the fabrication and characterization of optical planar waveguide in x-cut sodium-doped calcium barium niobate crystal by using C ion implantation. The guided-mode properties at the wavelength of 633 and 1539 nm are investigated through prism-coupling measurements, respectively. By applying direct end-face coupling arrangement, the near-field optical intensity distribution of waveguide modes is measured at 633 nm. For comparison, the modal profile of the same guided mode is also numerically calculated by the finite difference beam-propagation method via computer software BeamPROP. The transmission spectra of the waveguide before and after ion implantation treatments were investigated also. Our experiment results reveal that the waveguide could propagate light with transverse magnetic polarized direction only and it is assumed that the polarization selectivity of CBN crystal may responsible for this phenomenon.

  18. Hydrothermal method of synthesis of rare-earth tantalates and niobates

    DOEpatents

    Nyman, May D; Rohwer, Lauren E.S.; Martin, James E

    2012-10-16

    A hydrothermal method of synthesis of a family of rare-earth Group 5 oxides, where the Group 5 oxide is a niobate or tantalate. The rare-earth Group 5 oxides can be doped with suitable emitter ions to form nanophosphors.

  19. SOLITONS: Dark photovoltaic spatial solitons in a planar waveguide obtained by proton implantation in lithium niobate

    NASA Astrophysics Data System (ADS)

    Kruglov, V. G.; Shandarov, V. M.; Tan, Ya; Chen, F.; Kip, D.

    2008-11-01

    A photovoltaic dark spatial soliton is generated in a planar waveguide produced by the implantation of protons into a copper-doped lithium niobate crystal. Stationary soliton regimes are achieved at powers 90 and 30 μW at wavelengths 633 and 532 nm, respectively.

  20. Alkaline Phosphatase in Stem Cells

    PubMed Central

    Štefková, Kateřina; Procházková, Jiřina; Pacherník, Jiří

    2015-01-01

    Alkaline phosphatase is an enzyme commonly expressed in almost all living organisms. In humans and other mammals, determinations of the expression and activity of alkaline phosphatase have frequently been used for cell determination in developmental studies and/or within clinical trials. Alkaline phosphatase also seems to be one of the key markers in the identification of pluripotent embryonic stem as well as related cells. However, alkaline phosphatases exist in some isoenzymes and isoforms, which have tissue specific expressions and functions. Here, the role of alkaline phosphatase as a stem cell marker is discussed in detail. First, we briefly summarize contemporary knowledge of mammalian alkaline phosphatases in general. Second, we focus on the known facts of its role in and potential significance for the identification of stem cells. PMID:25767512

  1. Alkaline fuel cells applications

    NASA Astrophysics Data System (ADS)

    Kordesch, Karl; Hacker, Viktor; Gsellmann, Josef; Cifrain, Martin; Faleschini, Gottfried; Enzinger, Peter; Fankhauser, Robert; Ortner, Markus; Muhr, Michael; Aronson, Robert R.

    On the world-wide automobile market technical developments are increasingly determined by the dramatic restriction on emissions as well as the regimentation of fuel consumption by legislation. Therefore there is an increasing chance of a completely new technology breakthrough if it offers new opportunities, meeting the requirements of resource preservation and emission restrictions. Fuel cell technology offers the possibility to excel in today's motive power techniques in terms of environmental compatibility, consumer's profit, costs of maintenance and efficiency. The key question is economy. This will be decided by the costs of fuel cell systems if they are to be used as power generators for future electric vehicles. The alkaline hydrogen-air fuel cell system with circulating KOH electrolyte and low-cost catalysed carbon electrodes could be a promising alternative. Based on the experiences of Kordesch [K. Kordesch, Brennstoffbatterien, Springer, Wien, 1984, ISBN 3-387-81819-7; K. Kordesch, City car with H 2-air fuel cell and lead-battery, SAE Paper No. 719015, 6th IECEC, 1971], who operated a city car hybrid vehicle on public roads for 3 years in the early 1970s, improved air electrodes plus new variations of the bipolar stack assembly developed in Graz are investigated. Primary fuel choice will be a major issue until such time as cost-effective, on-board hydrogen storage is developed. Ammonia is an interesting option. The whole system, ammonia dissociator plus alkaline fuel cell (AFC), is characterised by a simple design and high efficiency.

  2. Silica in alkaline brines

    USGS Publications Warehouse

    Jones, B.F.; Rettig, S.L.; Eugster, H.P.

    1967-01-01

    Analysis of sodium carbonate-bicarbonate brines from closed basins in volcanic terranes of Oregon and Kenya reveals silica contents of up to 2700 parts per million at pH's higher than 10. These high concentrations of SiO 2 can be attributed to reaction of waters with silicates, and subsequent evaporative concentration accompanied by a rise in pH. Supersaturation with respect to amorphous silica may occur and persist for brines that are out of contact with silicate muds and undersaturated with respect to trona; correlation of SiO2 with concentration of Na and total CO2 support this interpretation. Addition of moredilute waters to alkaline brines may lower the pH and cause inorganic precipitation of substantial amounts of silica.

  3. Bifunctional alkaline oxygen electrodes

    NASA Technical Reports Server (NTRS)

    Swette, L.; Kackley, N.; Mccatty, S. A.

    1991-01-01

    The authors describe the identification and testing of electrocatalysts and supports for the positive electrode of moderate-temperature, single-unit, rechargeable alkaline fuel cells. Recent work on Na(x)Pt3O4, a potential bifunctional catalyst, is described, as well as the application of novel approaches to the development of more efficient bifunctional electrode structures. The three dual-character electrodes considered here showed similar superior performance; the Pt/RhO2 and Rh/RhO2 electrodes showed slightly better performance than the Pt/IrO2 electrode. It is concluded that Na(x)Pt3O4 continues to be a promising bifunctional oxygen electrode catalyst but requires further investigation and development.

  4. Experimental and simulated performance of lithium niobate 1-3 piezocomposites for 2 MHz non-destructive testing applications.

    PubMed

    Kirk, K J; Schmarje, N

    2013-01-01

    Lithium niobate piezocomposites have been investigated as the active element in high temperature resistant ultrasonic transducers for non-destructive testing applications up to 400°C. Compared to a single piece of lithium niobate crystal they demonstrate shorter pulse length by 3×, elimination of lateral modes, and resistance to cracking. In a 1-3 connectivity piezocomposite for high temperature use (200-400°C), lithium niobate pillars are embedded in a matrix of flexible high temperature sealant or high temperature cement. In order to better understand the design principles and constraints for use of lithium niobate in piezocomposites experiments and modelling have been carried out. For this work the lithium niobate piezocomposites were investigated at room temperature so epoxy filler was used. 1-3 connectivity piezocomposite samples were prepared with z-cut lithium niobate, pillar width 0.3-0.6mm, sample thickness 1-4mm, pillar aspect ratio (pillar height/width) 3-6, volume fraction 30 and 45%. Operating frequency was 1-2MHz. Experimental measurements of impedance magnitude and resonance frequency were compared with 3-D finite element modelling using PZFlex. Resonance frequencies were predicted within 0.05MHz and impedance magnitude within 2-5% for samples with pillar aspect ratio ≥3 for 45% volume fraction and pillar aspect ratio ⩾6 for 30% volume fraction. Laser vibrometry of pulse excitation of piezocomposite samples in air showed that the lithium niobate pillars and the epoxy filler moved in phase. Experiment and simulation showed that the thickness mode coupling coefficient k(t) of the piezocomposite was maintained at the lithium niobate bulk value of approximately 0.2 down to a volume fraction of 30%, consistent with calculations using the (Smith and Auld, 1991) model for piezocomposites. PMID:22784707

  5. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Laser damage resistance of a lithium niobate-tantalate bicrystal system

    NASA Astrophysics Data System (ADS)

    Skvortsov, L. A.; Stepantsov, E. S.

    1993-11-01

    The laser damage resistance of a bicrystal system prepared by solid-phase diffusive joining of specially prepared crystals of lithium niobate and lithium tantalate has been studied. This has been the first such study. The damage resistance of the interface is at least twice that of the lithium niobate surface. The damage resistance of the bicrystal is determined by the damage resistance of the lithium tantalate surface and is greater than 600 MW/cm2.

  6. Damage threshold of lithium niobate crystal under single and multiple femtosecond laser pulses: theoretical and experimental study

    NASA Astrophysics Data System (ADS)

    Meng, Qinglong; Zhang, Bin; Zhong, Sencheng; Zhu, Liguo

    2016-06-01

    The damage threshold of lithium niobate crystal under single and multiple femtosecond laser pulses has been studied theoretically and experimentally. Firstly, the model for the damage threshold prediction of crystal materials based on the improved rate equation has been proposed. Then, the experimental measure method of the damage threshold of crystal materials has been given in detail. On the basis, the variation of the damage threshold of lithium niobate crystal with the pulse duration has also been analyzed quantitatively. Finally, the damage threshold of lithium niobate crystal under multiple laser pulses has been measured and compared to the theoretical results. The results show that the transmittance of lithium niobate crystal is almost a constant when the laser pulse fluence is relative low, whereas it decreases linearly with the increase in the laser pulse fluence below the damage threshold. The damage threshold of lithium niobate crystal increases with the increase in the duration of the femtosecond laser pulse. And the damage threshold of lithium niobate crystal under multiple laser pulses is obviously lower than that irradiated by a single laser pulse. The theoretical data fall in good agreement with the experimental results.

  7. Modulators of intestinal alkaline phosphatase.

    PubMed

    Bobkova, Ekaterina V; Kiffer-Moreira, Tina; Sergienko, Eduard A

    2013-01-01

    Small molecule modulators of phosphatases can lead to clinically useful drugs and serve as invaluable tools to study functional roles of various phosphatases in vivo. Here, we describe lead discovery strategies for identification of inhibitors and activators of intestinal alkaline phosphatases. To identify isozyme-selective inhibitors and activators of the human and mouse intestinal alkaline phosphatases, ultrahigh throughput chemiluminescent assays, utilizing CDP-Star as a substrate, were developed for murine intestinal alkaline phosphatase (mIAP), human intestinal alkaline phosphatase (hIAP), human placental alkaline phosphatase (PLAP), and human tissue-nonspecific alkaline phosphatase (TNAP) isozymes. Using these 1,536-well assays, concurrent HTS screens of the MLSMR library of 323,000 compounds were conducted for human and mouse IAP isozymes monitoring both inhibition and activation. This parallel screening approach led to identification of a novel inhibitory scaffold selective for murine intestinal alkaline phosphatase. SAR efforts based on parallel testing of analogs against different AP isozymes generated a potent inhibitor of the murine IAP with IC50 of 540 nM, at least 65-fold selectivity against human TNAP, and >185 selectivity against human PLAP. PMID:23860652

  8. Alkaline battery, separator therefore

    NASA Technical Reports Server (NTRS)

    Schmidt, George F. (Inventor)

    1980-01-01

    An improved battery separator for alkaline battery cells has low resistance to electrolyte ion transfer and high resistance to electrode ion transfer. The separator is formed by applying an improved coating to an electrolyte absorber. The absorber, preferably, is a flexible, fibrous, and porous substrate that is resistant to strong alkali and oxidation. The coating composition includes an admixture of a polymeric binder, a hydrolyzable polymeric ester and inert fillers. The coating composition is substantially free of reactive fillers and plasticizers commonly employed as porosity promoting agents in separator coatings. When the separator is immersed in electrolyte, the polymeric ester of the film coating reacts with the electrolyte forming a salt and an alcohol. The alcohol goes into solution with the electrolyte while the salt imbibes electrolyte into the coating composition. When the salt is formed, it expands the polymeric chains of the binder to provide a film coating substantially permeable to electrolyte ion transfer but relatively impermeable to electrode ion transfer during use.

  9. Evaluation of Alkaline Cleaner Materials

    NASA Technical Reports Server (NTRS)

    Partz, Earl

    1998-01-01

    Alkaline cleaners used to process aluminum substrates have contained chromium as the corrosion inhibitor. Chromium is a hazardous substance whose use and control are described by environmental laws. Replacement materials that have the characteristics of chromated alkaline cleaners need to be found that address both the cleaning requirements and environmental impacts. This report will review environmentally friendly candidates evaluated as non-chromium alkaline cleaner replacements and methods used to compare those candidates one versus another. The report will also list characteristics used to select candidates based on their declared contents. It will also describe and evaluate methods used to discriminate among the large number of prospective candidates.

  10. Shape manipulation of ion irradiated Ag nanoparticles embedded in lithium niobate

    NASA Astrophysics Data System (ADS)

    Wolf, Steffen; Rensberg, Jura; Johannes, Andreas; Thomae, Rainer; Smit, Frederick; Neveling, Retief; Moodley, Mathew; Bierschenk, Thomas; Rodriguez, Matias; Afra, Boshra; Hasan, Shakeeb Bin; Rockstuhl, Carsten; Ridgway, Mark; Bharuth-Ram, Krish; Ronning, Carsten

    2016-04-01

    Spherical silver nanoparticles were prepared by means of ion beam synthesis in lithium niobate. The embedded nanoparticles were then irradiated with energetic 84Kr and 197Au ions, resulting in different electronic energy losses between 8.1 and 27.5 keV nm-1 in the top layer of the samples. Due to the high electronic energy losses of the irradiating ions, molten ion tracks are formed inside the lithium niobate in which the elongated Ag nanoparticles are formed. This process is strongly dependent on the initial particle size and leads to a broad aspect ratio distribution. Extinction spectra of the samples feature the extinction maximum with shoulders on either side. While the maximum is caused by numerous remaining spherical nanoparticles, the shoulders can be attributed to elongated particles. The latter could be verified by COMSOL simulations. The extinction spectra are thus a superposition of the spectra of all individual particles.

  11. Shape manipulation of ion irradiated Ag nanoparticles embedded in lithium niobate.

    PubMed

    Wolf, Steffen; Rensberg, Jura; Johannes, Andreas; Thomae, Rainer; Smit, Frederick; Neveling, Retief; Moodley, Mathew; Bierschenk, Thomas; Rodriguez, Matias; Afra, Boshra; Bin Hasan, Shakeeb; Rockstuhl, Carsten; Ridgway, Mark; Bharuth-Ram, Krish; Ronning, Carsten

    2016-04-01

    Spherical silver nanoparticles were prepared by means of ion beam synthesis in lithium niobate. The embedded nanoparticles were then irradiated with energetic (84)Kr and (197)Au ions, resulting in different electronic energy losses between 8.1 and 27.5 keV nm(-1) in the top layer of the samples. Due to the high electronic energy losses of the irradiating ions, molten ion tracks are formed inside the lithium niobate in which the elongated Ag nanoparticles are formed. This process is strongly dependent on the initial particle size and leads to a broad aspect ratio distribution. Extinction spectra of the samples feature the extinction maximum with shoulders on either side. While the maximum is caused by numerous remaining spherical nanoparticles, the shoulders can be attributed to elongated particles. The latter could be verified by COMSOL simulations. The extinction spectra are thus a superposition of the spectra of all individual particles. PMID:26902734

  12. Erbium localized doping into various cuts of lithium niobate and sapphire: a comparative study

    NASA Astrophysics Data System (ADS)

    Nekvindova, Pavla; Mackova, Anna; Perina, Vratislav; Cervena, Jarmila; Capek, Pavel; Schroefel, Josef; Spirkova, Jarmila; Oswald, Jiri

    2003-07-01

    Medium temperature (350 °C) localized doping of Er3+ was studied in lithium niobate (LN) and sapphire single crystal wafers that were cut in various crystallographic directions. It was found that the efficiency of the doping was connected with orientations of the substrate wafers of both LN and sapphire, and with the presence of mobile lithium ions in the structure of LN. The basic interstitial mechanism of erbium incorporation into the structure of sapphire and LN is in the latter accompanied with erbium for lithium ion exchange. While the rate of the interstitial diffusion was higher in the wafers oriented perpendicularly towards the cleavage planes of the crystals, ion exchange process was significant in the wafers cut in cleavage planes. Waveguiding properties in erbium doped lithium niobate originated rather from presence of erbium in the structure of the crystals than being a consequence of a weak proton exchange. Luminescence properties of the fabricated samples are also presented.

  13. Acoustically determined linear piezoelectric response of lithium niobate up to 1100 V

    SciTech Connect

    Patel, N.; Branch, D. W.; Cular, S.; Schamiloglu, E.

    2014-04-21

    We present a method to measure high voltages using the piezoelectric crystal lithium niobate without using voltage dividers. A 36° Y-X cut lithium niobate crystal was coupled to two acoustic transducers, where direct current voltages were applied from 128–1100 V. The time-of-flight through the crystal was determined to be linearly dependent on the applied voltage. A model was developed to predict the time-delay in response to the applied voltage. The results show a sensitivity of 17 fs/V with a measurement error of 1 fs/V was achievable using this method. The sensitivity of this method can be increased by measuring the acoustic wave after multiple passes through the crystal. This method has many advantages over traditional techniques such as: favorable scalability for larger voltages, ease of use, cost effectiveness, and compactness.

  14. Optical and holographic storage properties of F3, Cu, and Mg-doped lithium niobate

    NASA Technical Reports Server (NTRS)

    Beatty, M. E., III; Meredith, B. D.

    1978-01-01

    Several samples of iron, copper, and magnesium doped lithium niobate were tested to determine their storage properties which would be applicable to an optical data storage system and an integrated optics data preprocessor which makes use of holographic storage techniques. The parameters of interest were the diffraction efficiency, write power, write time, erase time, erase energy, and write sensitivity. Results of these parameters are presented. It was found that iron doped lithium niobate samples yielded the best results in all parameters except for a few percent higher diffraction efficiency in copper doped samples. The magnesium doped samples were extremely insensitive and are not recommended for use in holographic optical data storage and processing systems.

  15. Acoustically determined linear piezoelectric response of lithium niobate up to 1100 V

    NASA Astrophysics Data System (ADS)

    Patel, N.; Branch, D. W.; Schamiloglu, E.; Cular, S.

    2014-04-01

    We present a method to measure high voltages using the piezoelectric crystal lithium niobate without using voltage dividers. A 36° Y-X cut lithium niobate crystal was coupled to two acoustic transducers, where direct current voltages were applied from 128-1100 V. The time-of-flight through the crystal was determined to be linearly dependent on the applied voltage. A model was developed to predict the time-delay in response to the applied voltage. The results show a sensitivity of 17 fs/V with a measurement error of 1 fs/V was achievable using this method. The sensitivity of this method can be increased by measuring the acoustic wave after multiple passes through the crystal. This method has many advantages over traditional techniques such as: favorable scalability for larger voltages, ease of use, cost effectiveness, and compactness.

  16. Heterogeneous microring and Mach-Zehnder modulators based on lithium niobate and chalcogenide glasses on silicon.

    PubMed

    Rao, Ashutosh; Patil, Aniket; Chiles, Jeff; Malinowski, Marcin; Novak, Spencer; Richardson, Kathleen; Rabiei, Payam; Fathpour, Sasan

    2015-08-24

    Thin films of lithium niobate are wafer bonded onto silicon substrates and rib-loaded with a chalcogenide glass, Ge(23)Sb(7)S(70), to demonstrate strongly confined single-mode submicron waveguides, microring modulators, and Mach-Zehnder modulators in the telecom C band. The 200 μm radii microring modulators present 1.2 dB/cm waveguide propagation loss, 1.2 × 10(5) quality factor, 0.4 GHz/V tuning rate, and 13 dB extinction ratio. The 6 mm long Mach-Zehnder modulators have a half-wave voltage-length product of 3.8 V.cm and an extinction ratio of 15 dB. The demonstrated work is a key step towards enabling wafer scale dense on-chip integration of high performance lithium niobate electro-optical devices on silicon for short reach optical interconnects and higher order advanced modulation schemes. PMID:26368243

  17. Periodic domain patterning by electron beam of proton exchanged waveguides in lithium niobate

    NASA Astrophysics Data System (ADS)

    Chezganov, D. S.; Vlasov, E. O.; Neradovskiy, M. M.; Gimadeeva, L. V.; Neradovskaya, E. A.; Chuvakova, M. A.; Tronche, H.; Doutre, F.; Baldi, P.; De Micheli, M. P.; Shur, V. Ya.

    2016-05-01

    Formation of domain structure by electron beam irradiation in congruent lithium niobate covered by surface dielectric layer with planar and channel waveguides produced by Soft Proton Exchange (SPE) process has been studied. Formation of domains with arbitrary shapes as a result of discrete switching has been revealed. The fact was attributed to ineffective screening of depolarization field in the crystals with a surface layer modified by SPE process. The dependences of the domain sizes on the dose and the distance between irradiated areas have been revealed. Finally, we have demonstrated that electron beam irradiation of lithium niobate crystals with surface resist layer can produce high quality periodical domain patterns after channel waveguide fabrication. Second harmonic generation with normalized nonlinear conversion efficiency up to 48%/(W cm2) has been achieved in such waveguides.

  18. Synthesis of potassium niobates by the microwave-assisted solvothermal method

    NASA Astrophysics Data System (ADS)

    Duarte, T. M.; Honorio, L. M. C.; Brito, A. S.; Souza, J. K. D.; Longo, E.; Tranquilin, R. L.; Souza, A. G.; Santos, I. M. G.; Maia, A. S.

    2015-11-01

    Potassium niobates have been synthesized by different methods, but few papers use the microwave-assisted solvothermal method, with possibility of a deeper evaluation in this area. In this work, the synthesis of KNbO3, KNb3O8 and K4Nb6O17 was performed by calcinations of precursors obtained by the microwave-assisted solvothermal method. This study evaluates the influence of various synthesis parameters such as reaction time, pH of the reaction medium, K+ concentration in the precursor solution. The results show the formation of different niobates, KNbO3, KNb3O8, K4Nb6O17, depending on the short and long-range order of the precursor used in the post annealing process.

  19. Coded excitation of broadband terahertz using optical rectification in poled lithium niobate

    NASA Astrophysics Data System (ADS)

    Buma, T.; Norris, T. B.

    2005-12-01

    We demonstrate coded excitation of broadband terahertz for imaging applications. The encoded transmitter uses optical rectification of femtosecond laser pulses in poled lithium niobate patterned with a 53-bit binary phase code. The terahertz wave forms are detected by electro-optic sampling in zinc telluride. A digital pulse compression filter decodes the binary wave forms, producing broadband pulses at 1.0THz. A two-dimensional imaging experiment shows comparable performance between the encoded transmitter and a zinc telluride emitter.

  20. Modulational instability of polarization of light in a periodically poled lithium niobate chip

    NASA Astrophysics Data System (ADS)

    Hu, Ping; Liu, Kun; Chen, Xianfeng

    2016-01-01

    A critical physical phenomenon of polarization instability was observed in periodically poled lithium niobate, which reveals that tiny changes in the exterior conditions will have a remarkable effect on the polarization state of the output light. The instability shown here has a new physical mechanism from those in the weakly dispersive fiber, and such an in-chip chaos system is likely to promote an integrated chaos device behaving as biosensor, switch, and filter with high sensitivity or resolution.

  1. Photoconductive properties of organic-inorganic hybrid films of layered perovskite-type niobate.

    PubMed

    Saruwatari, Kazuko; Sato, Hisako; Idei, Tomochika; Kameda, Jun; Yamagishi, Akihiko; Takagaki, Atsushi; Domen, Kazunari

    2005-06-30

    A hybrid film of layered niobate and an organic amphiphile was prepared by the Langmuir-Blodgett (LB) method. Trimethylammonium-exchanged perovskite-type niobates ((CH(3))(3)NHSr(2)Nb(3)O(10)) were exfoliative to form an aqueous suspension. A monolayer of octadecylamine was produced on such an aqueous dispersion as a template for a hybrid film. A hybrid film was transferred as a Y-type LB film onto a hydrophilic glass plate or an ITO substrate. The structure of a deposited film was investigated with X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and atomic force microscopy (AFM) measurements, indicating a layer-by-layer structure with a single or double sheet of niobate as an inorganic composite. From the cyclic voltammogram on an ITO electrode modified with the Y-type 10 layered film, the lower edge of the conduction band of a niobate layer was determined to be - 0.6 V (vs Ag/AgCl). ac impedance and dc measurements were carried out on 1, 5, and 10-layered LB films (2 mm (electrode spacing) x 8 mm (width)) with aluminum electrodes. The freshly deposited samples behaved as an insulator under the illumination of 280 nm light (2.04 x 10(16) quanta s(-1)). Photoconductivities appeared, however, when they were preirradiated with a 150 W Xe lamp (ca. 2 x 10(18) quanta s(-1)) for 0.5-8.5 h. The process was denoted as photomodification. From the FT-IR and XRD results, it was deduced that the photomodification of LB films caused the decomposition of organic templates (octadecylammonium) accompanied by the collapse of layer-by-layer structures. dc analyses on the 5- and 10-layered films after photomodification also showed that they behaved as a photosemiconductor under UV light illumination. PMID:16852536

  2. Multicolour photochromism of colloidal solutions of niobate nanosheets intercalated with several kinds of metal ions.

    PubMed

    Kamada, Kai; Tanaka, Yosuke; Tokunaga, Motoko; Ueda, Taro; Hyodo, Takeo; Shimizu, Yasuhiro

    2016-02-25

    Colourless and transparent colloidal solutions of niobate nanosheets intercalated with some kinds of metal ions (M-NNS, M: metal) showed quasi-reversible photochromism. Ultraviolet light irradiation of the solutions induced a change in color while maintaining the transparency, and the color change was dependent on the metal ions. The coloured solutions were bleached by exposure to an oxidizing atmosphere. This cycle could be repeated several times. PMID:26821602

  3. Dependence of effective internal field of congruent lithium niobate on its domain configuration and stability

    SciTech Connect

    Das, Ranjit E-mail: souvik2cat@gmail.com Ghosh, Souvik E-mail: souvik2cat@gmail.com Chakraborty, Rajib E-mail: souvik2cat@gmail.com

    2014-06-28

    Congruent lithium niobate is characterized by its internal field, which arises due to defect clusters within the crystal. Here, it is shown experimentally that this internal field is a function of the molecular configuration in a particular domain and also on the stability of that particular configuration. The measurements of internal field are done using interferometric technique, while the variation of domain configuration is brought about by room temperature high voltage electric field poling.

  4. Interdomain region in single-crystal lithium niobate bimorph actuators produced by light annealing

    SciTech Connect

    Kubasov, I. V. Timshina, M. S.; Kiselev, D. A.; Malinkovich, M. D.; Bykov, A. S.; Parkhomenko, Yu. N.

    2015-09-15

    The interdomain region of a bidomain strucrture formed in 127°-cut lithium niobate single crystals using light annealing has been studied by optical and scanning probe microscopies. A periodic subdomain structure on the 180° macrodomain wall is visualized by piezoresponse force microscopy. The piezoresponse signal (polarization) is shown to be a power-law function of the domain width with an exponent n = 0.53.

  5. Graphene Based Surface Plasmon Polariton Modulator Controlled by Ferroelectric Domains in Lithium Niobate

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Zhao, Hua; Hu, Guangwei; Li, Siren; Su, Hang; Zhang, Jingwen

    2015-12-01

    We proposed a ferroelectric domain controlled graphene based surface plasmon polariton modulator. Ferroelectricity-induced electronic and optical property tuning of graphene by domain in lithium niobate was theoretically investigated considering both interband and intraband contributions of surface conductivity. With the corrected Sellmeier equation of lithium niobate, the propagation of transverse magnetic mode surface plasmon polaritons in an air/graphene/lithium niobate structure was studied when monolayer graphene was tuned by down polarization direction ferroelectric domain with different polarization levels. The length of the ferroelectric domain was optimized to be 90 nm for a wavelength of 5.0 μm with signal extinction per unit 14.7 dB/μm, modulation depth 474.1 dB/μm and figure of merit 32.5. This work may promote the study of highly efficient modulators and other ultra-compact nonvolatile electronic and photonic devices in which two-dimensional materials and ferroelectric materials are combined.

  6. Graphene Based Surface Plasmon Polariton Modulator Controlled by Ferroelectric Domains in Lithium Niobate.

    PubMed

    Wang, Hao; Zhao, Hua; Hu, Guangwei; Li, Siren; Su, Hang; Zhang, Jingwen

    2015-01-01

    We proposed a ferroelectric domain controlled graphene based surface plasmon polariton modulator. Ferroelectricity-induced electronic and optical property tuning of graphene by domain in lithium niobate was theoretically investigated considering both interband and intraband contributions of surface conductivity. With the corrected Sellmeier equation of lithium niobate, the propagation of transverse magnetic mode surface plasmon polaritons in an air/graphene/lithium niobate structure was studied when monolayer graphene was tuned by down polarization direction ferroelectric domain with different polarization levels. The length of the ferroelectric domain was optimized to be 90 nm for a wavelength of 5.0 μm with signal extinction per unit 14.7 dB/μm, modulation depth 474.1 dB/μm and figure of merit 32.5. This work may promote the study of highly efficient modulators and other ultra-compact nonvolatile electronic and photonic devices in which two-dimensional materials and ferroelectric materials are combined. PMID:26657622

  7. Influence of crystal structure on the luminescence of tantalates and niobates

    SciTech Connect

    Blasse, G.

    1988-01-01

    The luminescence of MgTa/sub 2/O/sub 6/ (trirutile structure) and ZnTa/sub 2/O/sub 6/ (tri-..cap alpha..-PbO/sub 2/ structure) are reported and discussed in connection with the luminescence of related compounds, especially the niobates with columbite structure. The maximum of the excitation band of the luminescence of the two tantalates is at 280 nm, a value lower in energy than that for the niobates. The emission band has its maximum at 500 nm (MgTa/sub 2/O/sub 6/) and 450 nm (ZnTa/sub 2/O/sub 6/). The quantum efficiency is low, reaching 15% (MgTa/sub 2/O/sub 6/) and 30% (ZnTa/sub 2/O/sub 6/) at 4.2 K. It is argued that the phenomena observed for these compounds indicate that the excitons, formed upon photoexcitation, are mobile, whereas in the columbite niobates they are localized due to self-trapping.

  8. Utilizing dynamic annealing during ion implantation: synthesis of silver nanoparticles in crystalline lithium niobate.

    PubMed

    Wolf, Steffen; Rensberg, Jura; Stöcker, Hartmut; Abendroth, Barbara; Wesch, Werner; Ronning, Carsten

    2014-04-01

    Silver nanoparticles (NPs) embedded in lithium niobate were fabricated via ion beam synthesis and are suitable for various plasmonic applications, e.g. enhancement of optical nonlinear effects. After room temperature silver implantation, annealing in the temperature range of 400-600 °C was performed in order to recrystallize the damaged lithium niobate surface layer. The shape of the silver NPs, their optical properties as well as the structural properties of their surrounding matrix have been analyzed for various annealing steps. TEM investigations show that annealing at 400 °C does not lead to recrystallization of the damaged lithium niobate. A recrystallization occurs upon increasing the annealing temperature to 500 or 600 °C, but simultaneously a second phase consisting of lithium triniobate forms. This is additionally supported by XRD measurements. By utilizing dynamic annealing, i.e. implanting silver at elevated temperatures of 400 °C, it is shown that the LiNbO3 matrix stays single crystalline during ion implantation and no LiNb3O8 is formed. This is additionally verified by comparing the positions of the surface plasmon resonances with calculations based on Mie's scattering theory. PMID:24598310

  9. Graphene Based Surface Plasmon Polariton Modulator Controlled by Ferroelectric Domains in Lithium Niobate

    PubMed Central

    Wang, Hao; Zhao, Hua; Hu, Guangwei; Li, Siren; Su, Hang; Zhang, Jingwen

    2015-01-01

    We proposed a ferroelectric domain controlled graphene based surface plasmon polariton modulator. Ferroelectricity-induced electronic and optical property tuning of graphene by domain in lithium niobate was theoretically investigated considering both interband and intraband contributions of surface conductivity. With the corrected Sellmeier equation of lithium niobate, the propagation of transverse magnetic mode surface plasmon polaritons in an air/graphene/lithium niobate structure was studied when monolayer graphene was tuned by down polarization direction ferroelectric domain with different polarization levels. The length of the ferroelectric domain was optimized to be 90 nm for a wavelength of 5.0 μm with signal extinction per unit 14.7 dB/μm, modulation depth 474.1 dB/μm and figure of merit 32.5. This work may promote the study of highly efficient modulators and other ultra-compact nonvolatile electronic and photonic devices in which two-dimensional materials and ferroelectric materials are combined. PMID:26657622

  10. The alkaline and alkaline-carbonatite magmatism from Southern Brazil

    NASA Astrophysics Data System (ADS)

    Ruberti, E.; Gomes, C. D. B.; Comin-Chiaramonti, P.

    2015-12-01

    Early to Late Cretaceous lasting to Paleocene alkaline magmatism from southern Brazil is found associated with major extensional structural features in and around the Paraná Basin and grouped into various provinces on the basis of several data. Magmatism is variable in size, mode of occurrence and composition. The alkaline rocks are dominantly potassic, a few occurrences showing sodic affinity. The more abundant silicate rocks are evolved undersaturated to saturated in silica syenites, displaying large variation in igneous forms. Less evolved types are restricted to subvolcanic environments and outcrops of effusive suites occur rarely. Cumulatic mafic and ultramafic rock types are very common, particularly in the alkali-carbonatitic complexes. Carbonatite bodies are represented by Ca-carbonatites and Mg-carbonatites and more scarcely by Fe-carbonatites. Available radiometric ages for the alkaline rocks fit on three main chronological groups: around 130 Ma, subcoveal with the Early Cretaceous flood tholeiites of the Paraná Basin, 100-110 Ma and 80-90 Ma (Late Cretaceous). The alkaline magmatism also extends into Paleocene times, as indicated by ages from some volcanic lavas. Geochemically, alkaline potassic and sodic rock types are distinguished by their negative and positive Nb-Ta anomalies, respectively. Negative spikes in Nb-Ta are also a feature common to the associated tholeiitic rocks. Sr-Nd-Pb systematics confirm the contribution of both HIMU and EMI mantle components in the formation of the alkaline rocks. Notably, Early and Late Cretaceous carbonatites have the same isotopic Sr-Nd initial ratios of the associated alkaline rocks. C-O isotopic Sr-Nd isotopic ratios indicate typical mantle signature for some carbonatites and the influence of post-magmatic processes in others. Immiscibility of liquids of phonolitic composition, derived from mafic alkaline parental magmas, has been responsible for the origin of the carbonatites. Close association of alkaline

  11. Structural and optical properties of ZnS/niobate composites synthesized by exfoliation/self-assembly processing

    SciTech Connect

    Chen Yufeng; Zhou Songhua; Yang Xiaojing; Ouyang Yi

    2010-04-15

    A new ZnS/niobate composite was first synthesized through two processes: (1) self-assembly of [Ca{sub 2}Nb{sub 3}O{sub 10}]{sub n}{sup n-} nanosheets in Zn(NH{sub 3}){sub 4}{sup 2+} solution; (2) formation of ZnS/niobate composite by adding Na{sub 2}S to the former reacting system. X-ray diffraction (XRD) result shows that the as-prepared ZnS/niobate composite can be indexed to tetrahedral symmetry with a=5.450(2) and c=16.904(7) A. The uniform distributions of Zn, Ca, Nb, S and O element in the particles were demonstrated by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The optical property of the composite was characterized by photoluminescence spectra and UV-vis absorption spectra. - Graphical abstract: ZnS/niobate composites were first synthesized by exfoliation/self-assembly processing. The composites were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), IR spectrum, UV-vis spectrum, and photoluminescent spectrum. The photoluminescence spectrum of the ZnS/niobate composite shows blue shift attributed to quantum sizes effects.

  12. Investigation of Local Structures in Layered Niobates by Solid-state NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Ting

    Research on ion-exchangeable layered niobates has attracted great attention due to their unique structures and corresponding variations in properties and applications, such as ion conductors, solid acids, and water splitting catalysts. Families of layered niobates include double-layered or triple-layered Dion-Jacobson type perovskites (ALaNb2O7, A = Cs, Rb, K, H; AM2Nb3O10, A = Rb, K, H; M = Sr, Ca), layered niobates with both edge and corner sharing of NbO6 octahedra (KNb3O8, HNb3O6, Nb 6O17 and H4Nb6O17) and many others. Lately, more developments in the layered niobates through a variety of topochemical manipulations have been achieved. The topochemical reactions include ion exchange, exfoliation, substitution, and etc. As a result, many new materials have been successfully prepared, for example, solid solutions (ALa2NbTi2O10, ACaLaNb2TiO 10 and ACa2Nb3-xTaxO10, etc.), nanosheets (HNb3O8, H4Nb6O17, HLaNb2O7, HCa2Nb3O10, etc., to intercalate with organic molecules such as tetrabutylammonium hydroxide or n-butylamines), and nanoscrolls (from H2K2Nb 6O17). While these structural modifications often induce improvements in properties, the fundamental mechanisms of improvements in properties upon the modifications, especially local structural arrangements are poorly understood, which is often limited by structural characterizations. Particularly, the characterizations of the exfoliated nanosheets can be difficult by conventional X-ray diffraction (XRD) method due to disordered structures. Alternatively, solid-state nuclear magnetic resonance (NMR) spectroscopy is a useful tool to study local structures in solids. The structural information can be extracted by examining intrinsic interactions, such as quadrupolar, chemical shielding, and dipolar interactions, which are all associated with local environments surrounding a specific nucleus, 1H or 93Nb in layered niobates. The ultimate goal of this dissertation is to understand the relationships between local structures of

  13. Structuring of material parameters in lithium niobate crystals with low-mass, high-energy ion radiation

    NASA Astrophysics Data System (ADS)

    Peithmann, K.; Eversheim, P.-D.; Goetze, J.; Haaks, M.; Hattermann, H.; Haubrich, S.; Hinterberger, F.; Jentjens, L.; Mader, W.; Raeth, N. L.; Schmid, H.; Zamani-Meymian, M.-R.; Maier, K.

    2011-10-01

    Ferroelectric lithium niobate crystals offer a great potential for applications in modern optics. To provide powerful optical components, tailoring of key material parameters, especially of the refractive index n and the ferroelectric domain landscape, is required. Irradiation of lithium niobate crystals with accelerated ions causes strong structured modifications in the material. The effects induced by low-mass, high-energy ions (such as 3He with 41 MeV, which are not implanted, but transmit through the entire crystal volume) are reviewed. Irradiation yields large changes of the refractive index Δn, improved domain engineering capability within the material along the ion track, and waveguiding structures. The periodic modification of Δn as well as the formation of periodically poled lithium niobate (PPLN) (supported by radiation damage) is described. Two-step knock-on displacement processes, 3He→Nb and 3He→O causing thermal spikes, are identified as origin for the material modifications.

  14. Characterization of active waveguides fabricated by ultralow-fluence swift heavy ion irradiation in lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Dong, Ningning; Chen, Feng; Jaque, Daniel; Benayas, Antonio; Qiu, Feng; Narusawa, Tadashi

    2011-03-01

    We report on the fabrication of neodymium-doped lithium niobate active planar waveguides based on the generation of non-overlapping nano-tracks by ultralow-fluence swift heavy ions. A combination of confocal luminescence, Raman and surface second harmonic investigations have evidenced the simultaneous presence of partial amorphization, damage and local compression of the lithium niobate network along the ion path, with these effects being at the basis of the refractive index modification. The potential application of the obtained waveguides in multi-functional laser devices has been discussed.

  15. 1-3 connectivity composite material made from lithium niobate and cement for ultrasonic condition monitoring at elevated temperatures.

    PubMed

    Shepherd, G; Cochran, A; Kirk, K J; McNab, A

    2002-05-01

    We have designed, manufactured and tested a piezoelectric composite material to operate at temperatures above 400 degrees C. The material is a 1-3 connectivity composite with pillars of Z-cut lithium niobate in a matrix of alumina cement. The composite material produced shorter pulses than a monolithic plate of lithium niobate and remained intact upon cooling. Results are presented from room temperature and high temperature testing. This material could be bonded permanently to a test object, making it possible to carry out condition monitoring over an extended period. A new excitation method was also developed to enable remote switching between array elements. PMID:12159936

  16. Photoinduced Ag deposition on periodically poled lithium niobate: Wavelength and polarization screening dependence

    NASA Astrophysics Data System (ADS)

    Sun, Yang; Nemanich, Robert J.

    2011-05-01

    This research addresses the wavelength dependence of the fabrication of Ag nanostructures through photoinduced deposition using single crystal ferroelectric lithium niobate as a template. The photoinduced deposition involves ultraviolent light illumination of polarity patterned lithium niobate while immersed in a AgNO3 solution. The results focus on the differences of the Ag nanostructure formation process on the positive and negative domains and domain boundaries. The results indicate that for below-band-gap excitation, a very low density of nanostructures is observed. However, for all above-gap-excitation wavelengths, deposition occurs on both polarity surfaces and at the domain boundaries. The density is greatest at the domain boundaries and reduced densities of smaller nanostructures are observed to form on both the positive and negative domains. The deposition on the domain surfaces is greatest for the shortest wavelengths, whereas the domain selectivity is increased for wavelengths just above the band gap. The external screening and weak band bending of single crystal lithium niobate introduces an enhanced electric field at the domain boundary. The enhanced electric field leads to migration of electrons to the domain boundary and consequently enhanced formation of Ag nanoparticles along the boundary. The variation in the reduction rate versus illumination wavelength is attributed to the light absorption depth and the competition between the photochemical and photoelectric deposition processes. To explore the transition from surface to bulk screening of the polarization charge, oxygen implanted PPLN surfaces were prepared and used for the Ag photoinduced deposition. Consistent with the transition to internal (bulk) screening, the Ag nanoparticle formation on the oxygen implanted PPLN surfaces showed suppressed boundary nanowire formation.

  17. Charge Transfer Stabilization of Late Transition Metal Oxide Nanoparticles on a Layered Niobate Support.

    PubMed

    Strayer, Megan E; Senftle, Thomas P; Winterstein, Jonathan P; Vargas-Barbosa, Nella M; Sharma, Renu; Rioux, Robert M; Janik, Michael J; Mallouk, Thomas E

    2015-12-30

    Interfacial interactions between late transition metal/metal oxide nanoparticles and oxide supports impact catalytic activity and stability. Here, we report the use of isothermal titration calorimetry (ITC), electron microscopy and density functional theory (DFT) to explore periodic trends in the heats of nanoparticle-support interactions for late transition metal and metal oxide nanoparticles on layered niobate and silicate supports. Data for Co(OH)2, hydroxyiridate-capped IrOx·nH2O, Ni(OH)2, CuO, and Ag2O nanoparticles were added to previously reported data for Rh(OH)3 grown on nanosheets of TBA0.24H0.76Ca2Nb3O10 and a layered silicate. ITC measurements showed stronger bonding energies in the order Ag < Cu ≈ Ni ≈ Co < Rh < Ir on the niobate support, as expected from trends in M-O bond energies. Nanoparticles with exothermic heats of interaction were stabilized against sintering. In contrast, ITC measurements showed endothermic interactions of Cu, Ni, and Rh oxide/hydroxide nanoparticles with the silicate and poor resistance to sintering. These trends in interfacial energies were corroborated by DFT calculations using single-atom and four-atom cluster models of metal/metal oxide nanoparticles. Density of states and charge density difference calculations reveal that strongly bonded metals (Rh, Ir) transfer d-electron density from the adsorbed cluster to niobium atoms in the support; this mixing is absent in weakly binding metals, such as Ag and Au, and in all metals on the layered silicate support. The large differences between the behavior of nanoparticles on niobate and silicate supports highlight the importance of d-orbital interactions between the nanoparticle and support in controlling the nanoparticles' stability. PMID:26651875

  18. Nanosecond terahertz optical parametric oscillator with a novel quasi phase matching scheme in lithium niobate.

    PubMed

    Molter, D; Theuer, M; Beigang, R

    2009-04-13

    We present an optical parametric oscillator pumped by a single mode Q-switched nanosecond Nd:YVO(4) laser for terahertz generation in periodically poled lithium niobate with a new phase matching scheme. This new method leads to an emission of terahertz radiation close to the Cherenkov angle and to a parallel propagation of the pump and signal wave. The emission frequency of this novel source is chosen by the poling period to 1.5 THz. For spectral narrowing the signal wave of the OPO is injection seeded. In the optical spectrum also cascaded processes are observed demonstrating a powerful generation of terahertz waves. PMID:19365488

  19. Characterization of lithium niobate electro-optic modulators at cryogenic temperatures

    SciTech Connect

    Morse, J.; McCammon, K.; McConaghy, C.; Masquelier, D.; Garrett, H.; Lowry, M.

    1994-01-01

    This paper reports on the operation of lithium niobate electro-optic waveguide modulators at temperatures down to 15{degrees}K. Commercial and laboratory fiber pigtailed devices have successfully been cooled without any increases in insertion loss from temperature induced stresses in device packaging. Three x-cut devices exhibited a linear increase in V{pi} voltage of 8%{plus_minus}1% when cooled from room temperature to {approximately} 20{degree}K. The broadband frequency response improved at lower temperature. A velocity-matched experimental modular has shown increased bandwidth when cooled to liquid nitrogen temperature.

  20. The role of defects in light induced domain inversion in lithium niobate

    NASA Astrophysics Data System (ADS)

    Sandmann, Christian; Dierolf, Volkmar

    2005-01-01

    Using the tightly focussed laser beam within a confocal luminescence microscope we were able to induce electric space charge fields through photoionization of trace defects in lithium niobate. These fields are sufficient to selectively induce domain inversion when a additional external field is applied that is below the regular coercive field. Once a domain is nucleated it grows laterally in a direction that can be dictated by the laser. We studied the presence and the range of the space charge fields utilizing the electro-optical effect and the Stark shifts observed in emission spectra of Er3+ ions.

  1. Shock-induced luminescence from X-cut quartz and Z-cut lithium niobate

    SciTech Connect

    Brannon, P.J.; Morris, R.W.; Asay, J.R.

    1983-01-01

    The spectral and spatial properties of shock-induced luminescence from X-cut quartz and Z-cut lithium niobate are observed using optical pyrometry and fast framing photography. In both cases the spatial emission patterns are heterogeneous for stresses just above dynamic yielding; the pattern becomes homogeneous to within the spatial resolution of the experiment as the stress is increased further. In addition, the luminescence in both cases increases abruptly after dynamic yielding. The emission spectrum from both samples is bank-like rather than blackbody and in the case of X-cut quartz is similar to the photoluminescence from structural defects.

  2. Mixed conduction and grain boundary effect in lithium niobate under high pressure

    SciTech Connect

    Wang, Qinglin; Liu, Cailong; Han, Yonghao E-mail: cc060109@qq.com; Gao, Chunxiao E-mail: cc060109@qq.com; Gao, Yang; Ma, Yanzhang

    2015-03-30

    The charge transport behavior of lithium niobate has been investigated by in situ impedance measurement up to 40.6 GPa. The Li{sup +} ionic conduction plays a dominant role in the transport process. The relaxation process is described by the Maxwell-Wagner relaxation arising at the interfaces between grains and grain boundaries. The grain boundary microstructure rearranges after the phase transition, which improves the bulk dielectric performance. The theoretical calculations show that the decrease of bulk permittivity with increasing pressure in the Pnma phase is caused by the pressure-induced enhancement of electron localization around O atoms, which limits the polarization of Nb-O electric dipoles.

  3. Niobium-complex-based syntheses of sodium niobate nanowires possessing superior photocatalytic properties.

    PubMed

    Saito, Kenji; Kudo, Akihiko

    2010-03-01

    Sodium niobates with nanowire morphology (NaNbO(3)-NW) were synthesized in a large scale by use of a niobium oxooxalate complex as the starting material. This NaNbO(3)-NW showed definitely enhanced photocatalytic activity for H(2) or O(2) evolution in the presence of sacrificial reagents and an overall water splitting under UV-light irradiation, as compared with a bulky counterpart (NaNbO(3)-B). This is the first example that an overall water splitting into H(2) and O(2) proceeded on the semiconductor nanowire photocatalyst. PMID:20104852

  4. Bidomain structures formed in lithium niobate and lithium tantalate single crystals by light annealing

    NASA Astrophysics Data System (ADS)

    Kubasov, I. V.; Kislyuk, A. M.; Bykov, A. S.; Malinkovich, M. D.; Zhukov, R. N.; Kiselev, D. A.; Ksenich, S. V.; Temirov, A. A.; Timushkin, N. G.; Parkhomenko, Yu. N.

    2016-03-01

    The bidomain structures produced by light external heating in z-cut lithium niobate and lithium tantalate single crystals are formed and studied. Interdomain regions about 200 and 40 μm wide in, respectively, LiNbO3 and LiTaO3 bidomain crystals are visualized and studied by optical microscopy and piezoresponse force microscopy. Extended chains and lines of domains in the form of thin layers with a width less than 10 μm in volume, which penetrate the interdomain region and spread over distances of up to 1 mm, are found.

  5. Simultaneous stimulated Raman scattering and second harmonic generation in periodically poled lithium niobate

    NASA Astrophysics Data System (ADS)

    McConnell, Gail; Ferguson, Allister I.

    2005-03-01

    Simultaneous stimulated Raman scattering (SRS) and second harmonic generation (SHG) are demonstrated in periodically poled lithium niobate (PPLN). Using a simple single-pass geometry, conversion efficiencies of up to 12% and 19% were observed for the SRS and SHG processes respectively. By changing the PPLN period interacting with the photonic crystal fibre based pump source and varying the PPLN temperature, the SHG signal was measured to be tunable from λ =584 nm to λ =679 nm. The SRS output spectrum was measured at λ=1583 nm, with a spectral full-width at half-maximum of λ =85 nm.

  6. Change in the structural imperfection of lithium niobate crystals doped with zinc

    SciTech Connect

    Litvinova, V. A. Litvinova, M. N.

    2015-01-15

    The changes in the degree of structural imperfection of lithium niobate (LiNbO{sub 3}) single crystals with an increase in the Li content and doping with zinc (to 1 wt %) have been investigated by the nonlinear optics methods and Raman spectroscopy. The conversion of broadband IR radiation in LiNbO{sub 3} crystals under noncritical (90°) phase-matching condition with vector interactions implemented is investigated. It is shown that the conversion efficiency, spectral width, and the position of maximum in the converted radiation spectrum depend on the ratio R = Li/Nb in LiNbO{sub 3} crystal and the impurity concentration.

  7. Fabrication of high-Q lithium niobate microresonators using femtosecond laser micromachining.

    PubMed

    Lin, Jintian; Xu, Yingxin; Fang, Zhiwei; Wang, Min; Song, Jiangxin; Wang, Nengwen; Qiao, Lingling; Fang, Wei; Cheng, Ya

    2015-01-01

    We report on fabrication of high-Q lithium niobate (LN) whispering-gallery-mode (WGM) microresonators suspended on silica pedestals by femtosecond laser direct writing followed by focused ion beam (FIB) milling. The micrometer-scale (diameter ~82 μm) LN resonator possesses a Q factor of ~2.5 × 10(5) around 1550 nm wavelength. The combination of femtosecond laser direct writing with FIB enables high-efficiency, high-precision nanofabrication of high-Q crystalline microresonators. PMID:25627294

  8. Suppression of optical damage at 532 nm in Holmium doped congruent lithium niobate.

    PubMed

    Barnes, Eftihia; O'Connell, Nathan H; Balli, Nicolas R; Pokhrel, Madhab; Movsesyan, Anush; Kokanyan, Edvard; Sardar, Dhiraj K

    2014-10-20

    Optical damage experiments were carried out in a series of Holmium doped congruent lithium niobate (Ho:cLN) crystals as a function of dopant concentration and laser intensity. The light induced beam distortion was recorded with a camera and a detector under the pseudo-Z-scan configuration. At 532 nm, strong suppression of the optical damage was observed for the 0.94 mol. % doped crystal. Increased resistance to optical damage was also observed at 488 nm. The suppression of the optical damage is predominantly attributed to the reduction of the Nb antisites due to the holmium doping. PMID:25401654

  9. Control of lateral domain spreading in congruent lithium niobate by selective proton exchange

    NASA Astrophysics Data System (ADS)

    Grilli, S.; Canalias, C.; Laurell, F.; Ferraro, P.; De Natale, P.

    2006-07-01

    Proton exchange was observed to increase the poling voltage for congruent lithium niobate. Patterned proton exchange was then used to control domain nucleation and inhibit broadening of reversed domains. Periodically proton exchanged samples were used to form domain gratings by electric field poling just using planar electrodes and without need for poling current control. The reversed domain gratings had a duty cycle faithfully reproducing that of the proton exchanged pattern with straight domain walls parallel to the x face, thus demonstrating that high-fidelity reversed domain patterning is possible to obtain by a relatively simple process.

  10. Structural, topographical and electrical properties of cerium doped strontium barium niobate (Ce:SBN60) ceramics

    NASA Astrophysics Data System (ADS)

    Raj, S. Gokul; Mathivanan, V.; Kumar, G. Ramesh; Yathavan, S.; Mohan, R.

    2016-05-01

    Tungsten bronze type cerium doped strontium barium niobate (Ce:SBN - Sr0.6B0.4Nb2O6) ceramics were synthesized by solid state process. Cerium was used as dopant to improve its electrical properties. Influence of Ce+ ions on the photoluminescence properties was investigated in detail. The grain size topographical behavior of SBN powders and their associated abnormal grain growth (AGG) were completely analyzed through SEM studies. Finally dielectric, measurement discusses about the broad phase transition observed due to cerium dopant The results were discussed in detail.

  11. Characterization of lithium niobate electro-optic modulators at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Morse, Jeffrey D.; McCammon, Kent G.; McConaghy, Charles F.; Masquelier, Don A.; Garrett, Henry E.; Lowry, Mark E.

    1994-05-01

    This paper reports on the operation of lithium niobate electro-optic waveguide modulators at temperatures down to 15 degree(s)K. Commercial and laboratory fiber pigtailed devices have successfully been cooled without any increases in insertion loss from temperature induced stresses in device packaging. Three x-cut devices exhibited a linear increase in Vpi voltage of 8% +/- 1% when cooled from room temperature to approximately 20 degree(s)K. The broadband frequency response improved at lower temperatures. A velocity-matched experimental modulator has shown increased bandwidth when cooled to liquid nitrogen temperature.

  12. Mode analysis of photonic crystal L3 cavities in self-suspended lithium niobate membranes

    SciTech Connect

    Diziain, Séverine Geiss, Reinhard; Zilk, Matthias; Schrempel, Frank; Kley, Ernst-Bernhard; Pertsch, Thomas; Tünnermann, Andreas

    2013-12-16

    We report on a multimodal analysis of photonic crystal L3 cavities milled in lithium niobate free-standing membranes. The classical L3 cavity geometry is compared to an L3 cavity containing a second lattice superimposed on the primary one. Those two different geometries are investigated in terms of vertical radiation and quality (Q) factor for each mode of the cavities. Depending on the cavity geometry, some modes undergo an enhancement of their vertical radiation into small angles while other modes experience a higher Q factor. Experimental characterizations are corroborated by three-dimensional finite difference time domain simulations.

  13. Effect of Ta doped on microstructure of sodium potassium niobate single crystal grown by flux method

    NASA Astrophysics Data System (ADS)

    Saravanan, R.; Rajesh, D.; Rajasekaran, S. V.; Perumal, R.; Chitra, M.; Jayavel, R.

    2013-06-01

    Single crystals of sodium potassium niobate (K0.5Na0.5)NbO3 (KNN) and 0.5mol%, 1mol% and 1.5 mol% tantalum oxide Ta2O5 doped KNN were grown by flux method. The formation of microstructure and domain structure was investigated for both pure and Ta doped KNN single crystals. The partial substitution of the B-site ion Nb5+ by the Ta5+ ion in the KNN single crystal results show that the decrease in the domain size and increase in the surface roughness with increasing concentration of dopants.

  14. Growth and morphological studies of sodium potassium niobate single crystal grown by flux method

    NASA Astrophysics Data System (ADS)

    Saravanan, R.; Rajesh, D.; Rajasekaran, S. V.; Perumal, R.; Chitra, M.; Jayavel, R.

    2015-06-01

    Single crystals of sodium potassium niobate (K0.5Na0.5)NbO3 (KNN) have been successfully grown by flux method. The flux used during crystal growth is K2CO3- Na2CO3 solid solution with addition of small amounts of B2O3 for lowering the growth temperature. From SEM and AFM analysis, surface morphology and the roughness value were investigated. The surface roughness was estimated to be about 6.96nm and surface morphology of grown crystals shows step and kink growth pattern due to change in supersaturation.

  15. Synchronously pumped optical parametric oscillation in periodically poled lithium niobate with 1-w average output power.

    PubMed

    Graf, T; McConnell, G; Ferguson, A I; Bente, E; Burns, D; Dawson, M D

    1999-05-20

    We report on a rugged all-solid-state laser source of near-IR radiation in the range of 1461-1601 nm based on a high-power Nd:YVO(4) laser that is mode locked by a semiconductor saturable Bragg reflector as the pump source of a synchronously pumped optical parametric oscillator with a periodically poled lithium niobate crystal. The system produces 34-ps pulses with a high repetition rate of 235 MHz and an average output power of 1 W. The relatively long pulses lead to wide cavity detuning tolerances. The comparatively narrow spectral bandwidth of <15 GHz is suitable for applications such as pollutant detection. PMID:18319928

  16. Estimation of random duty-cycle error in periodically poled lithium niobate by simple diffraction experiment

    NASA Astrophysics Data System (ADS)

    Dwivedi, Prashant Povel; Choi, Hee Joo; Kim, Byoung Joo; Cha, Myoungsik

    2014-02-01

    Random duty-cycle errors (RDE) in ferroelectric quasi-phase-matching (QPM) devices not only affect the frequency conversion efficiency, but also generate non-phase-matched background noise. Although such noise contribution can be evaluated by measuring second-harmonic generation (SHG) spectrum with tunable narrow-band lasers, the limited tuning ranges usually results in inaccurate measurement of pure noise. Instead of SHG, we took a diffraction pattern which is mathematically equivalent to the SHG spectrum, but can be obtained with greater simplicity. With our proposed method applied to periodically poled lithium niobate, RDE could be evaluated more accurately from the pure background noise measurement.

  17. Fabrication of high-Q lithium niobate microresonators using femtosecond laser micromachining

    PubMed Central

    Lin, Jintian; Xu, Yingxin; Fang, Zhiwei; Wang, Min; Song, Jiangxin; Wang, Nengwen; Qiao, Lingling; Fang, Wei; Cheng, Ya

    2015-01-01

    We report on fabrication of high-Q lithium niobate (LN) whispering-gallery-mode (WGM) microresonators suspended on silica pedestals by femtosecond laser direct writing followed by focused ion beam (FIB) milling. The micrometer-scale (diameter ~82 μm) LN resonator possesses a Q factor of ~2.5 × 105 around 1550 nm wavelength. The combination of femtosecond laser direct writing with FIB enables high-efficiency, high-precision nanofabrication of high-Q crystalline microresonators. PMID:25627294

  18. High-Q lithium niobate microdisk resonators on a chip for efficient electro-optic modulation.

    PubMed

    Wang, Jie; Bo, Fang; Wan, Shuai; Li, Wuxia; Gao, Feng; Li, Junjie; Zhang, Guoquan; Xu, Jingjun

    2015-09-01

    Lithium niobate (LN) microdisk resonators on a LN-silica-LN chip were fabricated using only conventional semiconductor fabrication processes. The quality factor of the LN resonator with a 39.6-μm radius and a 0.5-μm thickness is up to 1.19 × 10(6), which doubles the record of the quality factor 4.84 × 10(5) of LN resonators produced by microfabrication methods allowing batch production. Electro-optic modulation with an effective resonance-frequency tuning rate of 3.0 GHz/V was demonstrated in the fabricated LN microdisk resonator. PMID:26368411

  19. Backswitch poling in lithium niobate for high-fidelity domain patterning and efficient blue light generation

    NASA Astrophysics Data System (ADS)

    Batchko, Robert G.; Shur, Vladimir Y.; Fejer, Martin M.; Byer, Robert L.

    1999-09-01

    In nonlinear optics applications employing quasiphase matching, short-pitch domain gratings are generally required for the efficient generation of visible and ultraviolet light. Here we introduce an improved electric-field poling technique, which incorporates spontaneous backswitching and leads to uniform short-pitch domain structures. The total volume of backswitched material, and hence the duty cycle of the backswitched domain grating, can be accurately controlled. First-order single-pass continuous-wave second harmonic generation of 60 mW at 460 nm is achieved at 6.1%/W efficiency in 0.5-mm-thick 4-μm-period backswitch-poled lithium niobate.

  20. Porosity Dependence of Piezoelectric Properties for Porous Potassium Niobate System Ceramics

    NASA Astrophysics Data System (ADS)

    Wada, S.; Mase, Y.; Shimizu, S.; Maeda, K.; Fujii, I.; Nakashima, K.; Pulpan, P.; Miyajima, N.

    2011-10-01

    Porous potassium niobate (KNbO3, KN) system ceramics were prepared by a conventional sintering method using carbon black (CB) nanoparticles. First, KN nanoparticles with a size of 100 nm was mixed with CB nanoparticles and binder using ball milling with ethanol. The mixture was dried, and pressed into pellets using uniaxial pressing. After binder burnout, these ceramics was sintered in air. Their piezoelectric properties were measured and discussed a relationship between porosity and piezoelectric properties. As the results, with increasing porosity, piezoelectric g33 constant increased significantly, which suggested that porous ceramics were effective for stress sensor application.

  1. Ultrashort pulse chirp measurement via transverse second-harmonic generation in strontium barium niobate crystal

    SciTech Connect

    Trull, J.; Wang, B.; Parra, A.; Vilaseca, R.; Cojocaru, C.; Sola, I.; Sheng, Y.

    2015-06-01

    Pulse compression in dispersive strontium barium niobate crystal with a random size and distribution of the anti-parallel orientated nonlinear domains is observed via transverse second harmonic generation. The dependence of the transverse width of the second harmonic trace along the propagation direction allows for the determination of the initial chirp and duration of pulses in the femtosecond regime. This technique permits a real-time analysis of the pulse evolution and facilitates fast in-situ correction of pulse chirp acquired in the propagation through an optical system.

  2. Direct writing of ferroelectric domains on strontium barium niobate crystals using focused ultraviolet laser light

    SciTech Connect

    Boes, Andreas; Crasto, Tristan; Steigerwald, Hendrik; Mitchell, Arnan; Wade, Scott; Frohnhaus, Jakob; Soergel, Elisabeth

    2013-09-30

    We report ferroelectric domain inversion in strontium barium niobate (SBN) single crystals by irradiating the surface locally with a strongly focused ultraviolet (UV) laser beam. The generated domains are investigated using piezoresponse force microscopy. We propose a simple model that allows predicting the domain width as a function of the irradiation intensity, which indeed applies for both SBN and LiNbO{sub 3}. Evidently, though fundamentally different, the domain structure of both SBN and LiNbO{sub 3} can be engineered through similar UV irradiation.

  3. Synthesis and study of the luminescent properties of europium-doped yttrium niobate

    NASA Astrophysics Data System (ADS)

    Mester, A. Yu.; Mozharov, A. M.; Trofimov, A. N.; Zamoryanskaya, M. V.

    2016-05-01

    A method of synthesis of single-phase europium-doped yttrium niobate powders without using additional fluxes is developed. Using this method, a series of samples with different europium concentrations are synthesized. The phase composition, grain size, and luminescent properties of the synthesized powders are studied. The optimal dopant concentration corresponding to the maximum luminescence intensity is determined. It is shown that the decay time of the most intense luminescence line of europium decreases with increasing europium concentration. Comparative analysis of the luminescent properties of calcium tungstate and the luminescent properties of a synthesized sample with the highest luminescence intensity is performed.

  4. Ferroelectric domain gratings and Barkhausen spikes in potassium lithium tantalate niobate

    SciTech Connect

    Tong, X.; Yariv, A.; Zhang, M.; Agranat, A.J.; Hofmeister, R.; Leyva, V.

    1997-04-01

    The observation of Barkhausen current spikes during the recording of volume phase holograms in potassium lithium tantalate niobate is reported on. These spikes are due to the ferroelectric domain reversal induced by photorefractive space charge fields. Both {open_quotes}small{close_quotes} (1 nA) and {open_quotes}large{close_quotes} (100 nA) spikes are observed, which correspond to micro and macro domain reversal, respectively. The diffraction efficiency can change as much as 50{percent} during a single macrodomain switching. {copyright} {ital 1997 American Institute of Physics.}

  5. Field induced polarization and magnetization behaviour of Gd-doped lead magnesium niobate ceramics

    NASA Astrophysics Data System (ADS)

    Pandey, Adityanarayan; Gupta, Surya Mohan; Nigam, Arun Kumar

    2016-05-01

    Both superparaelectric and superparamagnetic behaviour has been observed in rare earth magnetic ion Gd3+ doped Lead Magnesium Niobate (Gd-PMN). Field induced polarization and magnetization studies reveal hystresis loss free P-E and M-H loop at 300K and 5K, respectively. Temperature dependence of inverse susceptibility plot shows deviation at a temperature "td" when fitted with the Curie-Weiss law. This deviation has been attributed to transition from paramagnetic to superparamagnetic behaviour as reported in amorphous Pd-Ni-Fe-P alloys.

  6. RECLAMATION OF ALKALINE ASH PILES

    EPA Science Inventory

    The objective of the study was to develop methods for reclaiming ash disposal piles for the ultimate use as agricultural or forest lands. The ashes studied were strongly alkaline and contained considerable amounts of salts and toxic boron. The ashes were produced from burning bit...

  7. Isolation of alkaline mutagens from complex mixtures

    SciTech Connect

    Ho, C.H.; Guerin, M.R.; Clark, B.R.; Rao, T.K.; Epler, J.L.

    1981-05-01

    A method for the preparative-scale enrichment of alkaline mutagens from complex natural and anthropogenic mixtures is described. Mutagenic alkaline fractions were isolated from cigarette smoke, crude petroleum, and petroleum substitutes derived from coal and shale.

  8. Nucleotide sequences encoding a thermostable alkaline protease

    DOEpatents

    Wilson, David B.; Lao, Guifang

    1998-01-01

    Nucleotide sequences, derived from a thermophilic actinomycete microorganism, which encode a thermostable alkaline protease are disclosed. Also disclosed are variants of the nucleotide sequences which encode a polypeptide having thermostable alkaline proteolytic activity. Recombinant thermostable alkaline protease or recombinant polypeptide may be obtained by culturing in a medium a host cell genetically engineered to contain and express a nucleotide sequence according to the present invention, and recovering the recombinant thermostable alkaline protease or recombinant polypeptide from the culture medium.

  9. Nucleotide sequences encoding a thermostable alkaline protease

    DOEpatents

    Wilson, D.B.; Lao, G.

    1998-01-06

    Nucleotide sequences, derived from a thermophilic actinomycete microorganism, which encode a thermostable alkaline protease are disclosed. Also disclosed are variants of the nucleotide sequences which encode a polypeptide having thermostable alkaline proteolytic activity. Recombinant thermostable alkaline protease or recombinant polypeptide may be obtained by culturing in a medium a host cell genetically engineered to contain and express a nucleotide sequence according to the present invention, and recovering the recombinant thermostable alkaline protease or recombinant polypeptide from the culture medium. 3 figs.

  10. Low Temperature 1D-Ising-like Behaviour of Cobalt Niobate

    NASA Astrophysics Data System (ADS)

    Munsie, Timothy; Kinross, Alison; Dube, Paul; Pomaranski, David; Kycia, Jan; Luke, Graeme

    2013-03-01

    Cobalt niobate, CoNb2O6, is a material that exhibits 1D-Ising-like behaviour at low temperatures, based primarily on chains of spins of the Co2+ atoms. Specific heat and magnetic susceptibility measurements on cobalt niobate have found magnetic transitions at 1.9 K and 2.9 K, in agreement with previous work. Specifically, we have performed specific heat measurements in zero field down to 330 mK and have mapped some of the field dependence of the specific heat above 2 K. The low temperature specific heat measurements show an increasingly long relaxation time, implying that the spins become increasingly decoupled from the lattice with decreasing temperature. We have also been the first group to examine the magnetic properties of this material with muon spin rotation (μSR). This work found that the cobalt moments remain largely dynamic on the microsecond timescale for temperatures well below 1.9 K, indicating that the ground state of CoNb2O6 is more complex than previously thought.

  11. Spectral evolution of Eu3+ doped Y3NbO7 niobate induced by temperature

    NASA Astrophysics Data System (ADS)

    Kim, K.-Y.; Durand, A.; Heintz, J.-M.; Veillere, A.; Jubera, V.

    2016-03-01

    A Eu3+ doped Y3NbO7 niobate powder was synthetized using a polymerizable complex route. It gave rise to nanometric particles that crystallized in the fluorine structure, corresponding to the Y3NbO7 phase. The thermal evolution of this powder was followed up to 1600 °C, using X-ray diffraction and optical characterizations. The fluorine structure was maintained in the whole temperature range. However, spectral evolution of the samples calcined above 900 °C showed a more complex situation. Emission spectra of powders heat treated at different temperatures showed an evolution of the emission lines that can be attributed first to a better crystallization of the niobate phase and second to its partial decomposition in favor of the formation of YNbO4 and Y2O3. Although the Y3NbO7 phase appeared stable up to 1650 °C, from X-ray diffraction analysis, spectral analysis showed that the local environment of the doping element is modified from 1100 °C.

  12. Periodic domain inversion in x-cut single-crystal lithium niobate thin film

    NASA Astrophysics Data System (ADS)

    Mackwitz, P.; Rüsing, M.; Berth, G.; Widhalm, A.; Müller, K.; Zrenner, A.

    2016-04-01

    We report the fabrication of periodically poled domain patterns in x-cut lithium niobate thin-film. Here, thin films on insulator have drawn particular attention due to their intrinsic waveguiding properties offering high mode confinement and smaller devices compared to in-diffused waveguides in bulk material. In contrast to z-cut thin film lithium niobate, the x-cut geometry does not require back electrodes for poling. Further, the x-cut geometry grants direct access to the largest nonlinear and electro-optical tensor element, which overall promises smaller devices. The domain inversion was realized via electric field poling utilizing deposited aluminum top electrodes on a stack of LN thin film/SiO2 layer/Bulk LN, which were patterned by optical lithography. The periodic domain inversion was verified by non-invasive confocal second harmonic microscopy. Our results show domain patterns in accordance to the electrode mask layout. The second harmonic signatures can be interpreted in terms of spatially, overlapping domain filaments which start their growth on the +z side.

  13. Heterogeneous microring and Mach-Zehnder modulators based on lithium niobate and chalcogenide glasses on silicon

    SciTech Connect

    Rao, Ashutosh; Patil, Aniket; Chiles, Jeff; Malinowski, Marcin; Novak, Spencer; Richardson, Kathleen; Rabiei, Payam; Fathpour, Sasan

    2015-08-20

    In this study, thin films of lithium niobate are wafer bonded onto silicon substrates and rib-loaded with a chalcogenide glass, Ge23Sb7S70, to demonstrate strongly confined single-mode submicron waveguides, microring modulators, and Mach-Zehnder modulators in the telecom C band. The 200 μm radii microring modulators present 1.2 dB/cm waveguide propagation loss, 1.2 × 105 quality factor, 0.4 GHz/V tuning rate, and 13 dB extinction ratio. The 6 mm long Mach-Zehnder modulators have a half-wave voltage-length product of 3.8 V.cm and an extinction ratio of 15 dB. The demonstrated work is a key step towards enabling wafer scale dense on-chip integration of high performance lithium niobate electro-optical devices on silicon for short reach optical interconnects and higher order advanced modulation schemes.

  14. Heterogeneous microring and Mach-Zehnder modulators based on lithium niobate and chalcogenide glasses on silicon

    DOE PAGESBeta

    Rao, Ashutosh; Patil, Aniket; Chiles, Jeff; Malinowski, Marcin; Novak, Spencer; Richardson, Kathleen; Rabiei, Payam; Fathpour, Sasan

    2015-08-20

    In this study, thin films of lithium niobate are wafer bonded onto silicon substrates and rib-loaded with a chalcogenide glass, Ge23Sb7S70, to demonstrate strongly confined single-mode submicron waveguides, microring modulators, and Mach-Zehnder modulators in the telecom C band. The 200 μm radii microring modulators present 1.2 dB/cm waveguide propagation loss, 1.2 × 105 quality factor, 0.4 GHz/V tuning rate, and 13 dB extinction ratio. The 6 mm long Mach-Zehnder modulators have a half-wave voltage-length product of 3.8 V.cm and an extinction ratio of 15 dB. The demonstrated work is a key step towards enabling wafer scale dense on-chip integration ofmore » high performance lithium niobate electro-optical devices on silicon for short reach optical interconnects and higher order advanced modulation schemes.« less

  15. When Halides Come to Lithium Niobate Nanopowders Purity and Morphology Assistance.

    PubMed

    Lamouroux, Emmanuel; Badie, Laurent; Miska, Patrice; Fort, Yves

    2016-03-01

    The preparation of pure lithium niobate nanopowders was carried out by a matrix-mediated synthesis approach. Lithium hydroxide and niobium pentachloride were used as precursors. The influence of the chemical environment was studied by adding lithium halide (LiCl or LiBr). After thermal treatment of the precursor mixture at 550 °C for 30 min, the morphology of the products was obtained from transmission electron microscopy and dynamic light scattering, whereas the crystallinity and phase purity were characterized by X-ray diffraction and UV-visible and Raman spectroscopies. Our results point out that the chemical environment during lithium niobate formation at 550 °C influences the final morphology. Moreover, direct and indirect band-gap energies have been determined from UV-visible spectroscopy. Their values for the direct-band-gap energies range from 3.97 to 4.36 eV with a slight dependence on the Li/Nb ratio, whereas for the indirect-band-gap energies, the value appears to be independent of this ratio and is 3.64 eV. No dependence of the band-gap energies on the average crystallite and nanoparticle sizes is observed. PMID:26859157

  16. Nanoparticles in the zirconia-europium niobate system via hydrothermal route.

    PubMed

    Hirano, Masanori; Dozono, Hayato

    2013-10-01

    The effect of the composition on the hydrothermal formation, structure, and properties of nanocrystalline luminescent materials in the zirconia (ZrO2)-europium niobate 1/4(Eu3NbO7) system was investigated. In the composition range 40 < or = ZrO2 mol% < or = 90, nanocrystalline particles with crystallite size 6.0-7.6 nm that were hydrothermally formed from the precursor solutions of NbCl5, ZrOCI2, and EuCl3 under weakly basic conditions at 240 degrees C showed cubic structure. The lattice parameter when estimated as a single cubic phase linearly decreased as the concentration of ZrO2 increased. The presence of zirconia component effectively promoted the formation of nanocrystals containing the niobate, Eu3NbO7 under hydrothermal condition. The nanocrystalline particles could be excited by ultraviolet light 395 nm (f-f transition) and emitted orange (590 nm) and red light (610 nm) corresponding to 5D0 --> 7F1 and 5D0 --> 7F2 transitions of Eu3+, respectively. The intensity of the electric dipole transition (5D0 --> 7F2) that was expressed in values relative to the magnetic dipole transition (5D0 --> 7F1) increased with increased heat-treatment temperature in the range from 950 to 1200 degrees C. PMID:24245134

  17. Heat capacity, enthalpy and entropy of bismuth niobate and bismuth tantalate

    SciTech Connect

    Hampl, M.; Strejc, A.; Sedmidubsky, D.; Ruzicka, K.; Hejtmanek, J.; Leitner, J. . E-mail: jindrich.leitner@vscht.cz

    2006-01-15

    The heat capacity and the heat content of bismuth niobate BiNbO{sub 4} and bismuth tantalate BiTaO{sub 4} were measured by the relaxation method and Calvet-type heat flux calorimetry. The temperature dependencies of the heat capacities in the form C{sub p} {sub m}=128.628+0.03340 T-1991055/T {sup 2}+136273131/T {sup 3} (J K{sup -1} mol{sup -1}) and 133.594+0.02539 T-2734386/T {sup 2}+235597393/T {sup 3} (J K{sup -1} mol{sup -1}) were derived for BiNbO{sub 4} and BiTaO{sub 4}, respectively, by the least-squares method from the experimental data. Furthermore, the standard molar entropies at 298.15 K S {sub m}(BiNbO{sub 4})=147.86 J K{sup -1} mol{sup -1} and S {sub m}(BiTaO{sub 4})=149.11 J K{sup -1} mol{sup -1} were assessed from the low temperature heat capacity measurements. To complete a set of thermodynamic data of these mixed oxides an attempt was made to estimate the values of the heat of formation from the constituent binary oxides. -- Graphical abstract: Heat content of bismuth niobate and bismuth tantalate-experimental points determined by the drop method and temperature dependencies obtained by the simultaneous fit of heat capacity and heat content data.

  18. Electrochemical reactions of layered niobate material as novel anode for sodium ion batteries

    NASA Astrophysics Data System (ADS)

    Nakayama, Hideki; Nose, Masafumi; Nakanishi, Shinji; Iba, Hideki

    2015-08-01

    The electrochemical performances of layered niobium oxide materials were investigated for the first time as novel anode active materials for the sodium-ion battery. The layered niobate with the formula KNb3O8 was synthesized by a solid-state reaction and has been evaluated as an anode electrode by a cyclic voltammetry technique and galvanostatic charge/discharge tests. The crystal structure of KNb3O8 contains the NbO6 octahedral units and potassium alkali-metal ions interlayer to form the layered structure. KNb3O8 has a redox reaction around 1 V vs. Na/Na+ and has a reversible capacity of 104 mAh/g corresponding to the 1.7 Na+ insertion/extraction in the KNb3O8 structure. The Nb K-edge X-ray absorption near edge structure (XANES) shows that the Nb oxidation state is converted from Nb5+ to Nb4+ during the Na+ insertion stage, and reversibly recovered to Nb5+ during the Na+ extraction stage. This is the first report that the layered niobate of KNb3O8 reversibly reacts with Na+ at the potential around 1 V vs. Na/Na+ via the Nb5+/4+ redox reaction.

  19. Bending waveguides made in x-cut lithium niobate crystals for technological applications

    NASA Astrophysics Data System (ADS)

    Guarepi, V.; Perrone, C.; Aveni, M.; Videla, F.; Torchia, GA

    2015-12-01

    In this paper we analyse the performance of several designs of integrated optical deviators made in x-cut lithium niobate crystals by means of femtosecond laser writing using the double line approach. Straight and bent guiding structures have been designed and implemented using this technique. Well-confined propagation modes at communication wavelengths (1.55 μm) were conducted in these structures with acceptable overall losses (less than 2 dB cm-1). Further, a discussion about the optical propagation losses for curved and straight deviators devices is included in this work. At a low aperture angle (less than 0.2°), as expected, low losses were determined for both structures; however, a weak output light was observed for large angles (greater than 0.2°) in the straight optical circuits. In contrast, a smooth variation of the output was measured for the bent structures. The results presented in this paper support the possibility of the technological implementation of integrated optical circuits for optical communications fabricated with ultrashort laser writing in lithium niobate crystals. In addition, some hypotheses of loss mechanisms that are normally not considered are discussed in order to explain the differences between the measured values and predictions obtained by calculating with the usual models.

  20. Guided resonances on lithium niobate for extremely small electric field detection investigated by accurate sensitivity analysis.

    PubMed

    Qiu, Wentao; Ndao, Abdoulaye; Lu, Huihui; Bernal, Maria-Pilar; Baida, Fadi Issam

    2016-09-01

    We present a theoretical study of guided resonances (GR) on a thin film lithium niobate rectangular lattice photonic crystal by band diagram calculations and 3D Finite Difference Time Domain (FDTD) transmission investigations which cover a broad range of parameters. A photonic crystal with an active zone as small as 13μm×13μm×0.7μm can be easily designed to obtain a resonance Q value in the order of 1000. These resonances are then employed in electric field (E-field) sensing applications exploiting the electro optic (EO) effect of lithium niobate. A local field factor that is calculated locally for each FDTD cell is proposed to accurately estimate the sensitivity of GR based E-field sensor. The local field factor allows well agreement between simulations and reported experimental data therefore providing a valuable method in optimizing the GR structure to obtain high sensitivities. When these resonances are associated with sub-picometer optical spectrum analyzer and high field enhancement antenna design, an E-field probe with a sensitivity of 50 μV/m could be achieved. The results of our simulations could be also exploited in other EO based applications such as EEG (Electroencephalography) or ECG (Electrocardiography) probe and E-field frequency detector with an 'invisible' probe to the field being detected etc. PMID:27607627

  1. Porous calcium niobate nanosheets prepared by an exfoliation-restacking route.

    PubMed

    Hashemzadeh, Fatemeh

    2016-01-01

    The single phase layered perovskite-type niobate KCa2Nb3O10 was obtained by a solid state reaction of the starting materials (K2CO3, CaCO3 and Nb2O5) at 1,200 °C. Then the H(+)-exchanged form (HCa2Nb3O10) was successfully exfoliated into colloidal porous single layers on the intercalating action of tetra(butyl)ammonium ion. The various characterization techniques such as X-ray diffraction (XRD), field-emission scanning electron microscopy, N2 absorption-desorption and diffuse reflectance UV-visible spectrometry gave important information on the unusual structural features of the perovskite-related niobate nanosheets. XRD analysis of the exfoliated nanosheets showed a unique profile with wide peaks that represented individual molecular aspects of the nanosheets. The Brunauer-Emmett-Teller isotherm of the exfoliated coiled nanosheets showed a sharp increase in the surface area by a factor of >30 in comparison to parent layered material, which is due to the exfoliation and restacking process. The nanosheets in this study were also found to act as a semiconductor with a wide band gap that is due to the quantum size effect. PMID:27003079

  2. Argon plasma inductively coupled plasma reactive ion etching study for smooth sidewall thin film lithium niobate waveguide application

    NASA Astrophysics Data System (ADS)

    Ulliac, G.; Calero, V.; Ndao, A.; Baida, F. I.; Bernal, M.-P.

    2016-03-01

    Lithium Niobate (LN) exhibits unique physical properties such as remarkable electro-optical coefficients and it is thus an excellent material for a wide range of fields like optic communications, lasers, nonlinear optical applications, electric field optical sensors etc. In order to further enhance the optical device performance and to be competitive with silicon photonics, sub-micrometric thickness lithium niobate films are crucial. A big step has been achieved with the development of LN thin films by using smart cut technology and wafer bonding and these films are nowadays available in the market. However, it is a challenge to obtain the requirements of the high quality thin LN film waveguide. In this letter, we show smooth ridge waveguides fabricated on 700 nm thickness thin film lithium niobate (TFLN). The fabrication has been done by developing and optimizing three steps of the technological process, the mask fabrication, the plasma etching, and a final cleaning wet etching step in order to remove the lithium niobate redeposition on the side walls. We have obtained single mode propagation with light overall losses of only 5 dB/cm.

  3. Development of alkaline fuel cells.

    SciTech Connect

    Hibbs, Michael R.; Jenkins, Janelle E.; Alam, Todd Michael; Janarthanan, Rajeswari; Horan, James L.; Caire, Benjamin R.; Ziegler, Zachary C.; Herring, Andrew M.; Yang, Yuan; Zuo, Xiaobing; Robson, Michael H.; Artyushkova, Kateryna; Patterson, Wendy; Atanassov, Plamen Borissov

    2013-09-01

    This project focuses on the development and demonstration of anion exchange membrane (AEM) fuel cells for portable power applications. Novel polymeric anion exchange membranes and ionomers with high chemical stabilities were prepared characterized by researchers at Sandia National Laboratories. Durable, non-precious metal catalysts were prepared by Dr. Plamen Atanassov's research group at the University of New Mexico by utilizing an aerosol-based process to prepare templated nano-structures. Dr. Andy Herring's group at the Colorado School of Mines combined all of these materials to fabricate and test membrane electrode assemblies for single cell testing in a methanol-fueled alkaline system. The highest power density achieved in this study was 54 mW/cm2 which was 90% of the project target and the highest reported power density for a direct methanol alkaline fuel cell.

  4. Processing and Reduced Sintering Temperature of Relaxor Ferroelectric Lead Zinc Niobate - Lead Nickel Niobate/lead Titanate Ceramics for Capacitor Applications

    NASA Astrophysics Data System (ADS)

    Vierheilig, Albert A.

    This dissertation investigates processing and property issues between relaxor ferroelectric Lead Zinc Niobate(PZN) and Lead Nickel Niobate(PNN), and the normal ferroelectric, Lead Titanate(PT). These materials were studied with regard to dielectric properties for potential usage in capacitor applications. Compositions in the xPZN-(1-x)PNN binary system were prepared over a range of x = 0 to x = 0.94. The use of the mixed oxide processing technique resulted in substantial pyrochlore phase formation while use of the B-site precursor technique significantly reduced the pyrochlore phase. Peak dielectric constant was a maximum at x = 0.70, with a value of 8,800 at a T_ c of 46 ^circC, following firing at 1125^circC/2 hours. The addition of PT to the PZN-PNN system was performed to optimize dielectric properties. A composition was identified which possessed a room temperature dielectric constant of 12,000 (0.46PZN-0.46PNN-0.08PT). To further optimize dielectric properties, several processing variables were studied, including excess PbO additions to starting batches, firing configuration, powder purity and post-fire thermal annealing. Thermal annealing was found to improve dielectric constant by 50% in the x = 0.65, x = 0.75 and 0.46PZN-0.46PNN -0.08PT systems. The x = 0.75 composition showed an increase in dielectric constant, despite the increased amount of pyrochlore phase present with increased annealing time. The other compositions showed negligible pyrochlore phase for all firing temperatures studied. The increase in K was due to increased grain development and decreased grain boundary phase. A reduction in processing temperature from 1075 to 950^circC using lithium -based fluxing sintering aids was demonstrated in the 0.46PZN -0.46PNN-0.08PT composition, with an improvement in density to 96% with only a 1% Li^+ concentration. Despite this large improvement, dielectric constant improved minimally. A systematic study comparing the effects of LiNO _3, Li_2CO_3 and Li

  5. Alkaline fuel cell performance investigation

    NASA Technical Reports Server (NTRS)

    Martin, R. E.; Manzo, M. A.

    1988-01-01

    An exploratory experimental fuel cell test program was conducted to investigate the performance characteristics of alkaline laboratory research electrodes. The objective of this work was to establish the effect of temperature, pressure, and concentration upon performance and evaluate candidate cathode configurations having the potential for improved performance. The performance characterization tests provided data to empirically establish the effect of temperature, pressure, and concentration upon performance for cell temperatures up to 300 F and reactant pressures up to 200 psia. Evaluation of five gold alloy cathode catalysts revealed that three doped gold alloys had more than two times the surface areas of reference cathodes and therefore offered the best potential for improved performance.

  6. Alkaline fuel cell performance investigation

    NASA Technical Reports Server (NTRS)

    Martin, R. E.; Manzo, M. A.

    1988-01-01

    An exploratory experimental fuel cell test program was conducted to investigate the performance characteristics of alkaline laboratory research electrodes. The objective of this work was to establish the effect of temperature, pressure, and concentration upon performance and evaluate candidate cathode configurations having the potential for improved performance. The performance characterization tests provided data to empirically establish the effect of temperature, pressure, and concentration upon performance for cell temperatures up to 300 F and reactant pressures up to 200 psia. Evaluation of five gold alloy cathode catalysts revealed that three doped gold alloys had more that two times the surface areas of reference cathodes and therefore offered the best potential for improved performance.

  7. Anode conductor for alkaline cells

    SciTech Connect

    Schrenk, D.J.; Murphy, P.E.

    1988-12-13

    This patent describes an electrochemical cell comprised of an anode comprised of zinc; a cathode; and alkaline electrolyte; and a current collector comprised of a silicon bronze alloy that is comprised of 85-98% by weight copper and 1-5% by weight silicon with the remainder being comprised of at least one of manganese, iron, zinc, aluminum, tin, lead, or mixtures thereof; and a strip of metal tab stock welded to the current collector, the tab stock being a metal other than silicon bronze alloy.

  8. Enhanced Photocatalytic Activity of TiO2 - niobate nanosheet composites

    SciTech Connect

    Liu, Jian; Nichols, Eric; Howe, Jane Y; Misture, S T

    2013-01-01

    Protonized niobate nanosheets H1.8Bi0.2CaNaNb3O10 were synthesized using a new, organic-free simultaneous ion-exchange and exfoliation process from the Aurivillius phase Bi2CaNaNb3O12. Nanosheet/TiO2 composites were prepared by thermal treatment of physical mixtures of commercially available anatase TiO2 and the nanosheet suspension. Methylene blue dye degradation studies for the composite show a clear correlation between the methylene blue surface adsorption and the degradation rate. The composite exhibits strongly enhanced photocatalytic activity as the calcination temperature increases, suggesting the possibility of the charge transfer at BCNN-TiO2 interface and the existence of Nb5+ and O2- acid-base pairs. Both phenomena are attributed to the processing approach, which includes topochemcial dehydration of the BCNN nanosheets during heat treatment.

  9. Photorefractive properties of paraelectric potassium lithium tantalate niobate crystal doped with iron

    NASA Astrophysics Data System (ADS)

    Tian, Hao; Zhou, Zhongxiang; Gong, Dewei; Wang, Haifeng; Jiang, Yongyuan; Hou, Chunfeng

    2008-03-01

    We report the successful growth of paraelectric potassium lithium tantalate niobate (KLTN) single crystal doped with iron. Detailed investigations have been made on the photorefractive properties of the as-grown crystal. The key parameters such as space-charge field, grating response time, photorefractive sensitivity and sign of the dominant charge carrier were obtained by two-wave mixing technique. 1.7 mm thick sample exhibits a high diffraction efficiency of 78% at the external field of 3.3 kV/cm and a sensitivity of 1.49 × 10-10E0 cm2/J. The two-wave mixing gain coefficient increases linearly with external field, and reaches a large value of 19.4 cm-1 at 4 kV/cm. Based on experimental results, iron is an effective dopant to KLTN which shows high diffraction efficiency and two-wave mixing gain coefficient.

  10. Potassium Niobate Nanolamina: A Promising Adsorbent for Entrapment of Radioactive Cations from Water

    PubMed Central

    Sun, Jin; Yang, Dongjiang; Sun, Cuihua; Liu, Long; Yang, Shuanglei; (Alec) Jia, Yi; Cai, Rongsheng; Yao, Xiangdong

    2014-01-01

    Processing and managing radioactive waste is a great challenge worldwide as it is extremely difficult and costly; the radioactive species, cations or anions, leaked into the environment are a serious threat to the health of present and future generations. We report layered potassium niobate (K4Nb6O17) nanolamina as adsorbent to remove toxic Sr2+, Ba2+ and Cs+ cations from wastewater. The results show that K4Nb6O17 nanolamina can permanently confine the toxic cations within the interlayer spacing via a considerable deformation of the metastable layered structure during the ion exchange process. At the same time, the nanolaminar adsorbent exhibits prompt adsorption kinetics, high adsorption capacity and selectivity, and superior acid resistance. These merits make it be a promising material as ion exchanger for the removal of radioactive cations from wastewater. PMID:25472721

  11. Spectral broadening in lithium niobate in a self-diffraction geometry using ultrashort pulses

    NASA Astrophysics Data System (ADS)

    Dharmadhikari, Jayashree A.; Dota, Krithika; Mathur, Deepak; Dharmadhikari, Aditya K.

    2016-05-01

    We report on broadband light generation in the impulsive regime in an un-doped lithium niobate (LiNbO3) crystal by two femtosecond laser pulses (36 fs) from a Ti-sapphire laser amplifier. We systematically investigate the role of incident intensity on spectral broadening. At relatively low incident intensity (0.7 TW cm-2), spectral broadening in the transmitted beam occurs due to the combined effect of self-phase modulation and cross-phase modulation. At higher incident intensity (10.2 TW cm-2), we observe generation of as many as 21 anti-Stokes orders due to coherent anti-Stokes Raman scattering in self-diffraction geometry. Moreover, we observe order-dependent spectral broadening of anti-Stokes lines that may be attributed to the competition with other nonlinear optical effects like cross-phase modulation.

  12. Multiplicity of europium centers in doped stoichiometric crystals of lithium niobate

    NASA Astrophysics Data System (ADS)

    Kaplyanskii, A. A.; Kapphan, S.; Kutsenko, A. B.; Polgar, K.; Skvortsov, A. P.

    2007-04-01

    The optical spectra of europium-doped stoichiometric lithium niobate (LiNbO3:Eu3+) crystals have been studied using combined excitation-luminescence spectroscopy in the range of 5D0 → 7F1, 7F0 optical transitions. Analysis of the results shows that Eu3+ ions can occupy 14 energetically nonequivalent positions in the LiNbO3 crystal lattice. This multiplicity of impurity centers is related to possible variants of the incorporation of Eu3+ ions into the LiNbO3 crystal lattice and the compensation of excess charge. Energy positions of the 5D0 level and the lowest sublevel of the 7F1 Stark multiplet are determined for Eu3+ centers of all 14 types.

  13. Three- and two-photon upconversion luminescence switching in Tm/Yb-codoped sodium niobate nanophosphor

    NASA Astrophysics Data System (ADS)

    Kumar, Kagola Upendra; Silva, Wagner Ferreira; Venkata Krishnaiah, Kummara; Jayasankar, Chalicheemalapalli Kulala; Jacinto, Carlos

    2014-01-01

    Intense infrared-to-visible upconversion (UC) emission in Tm/Yb-codoped sodium niobate (NaNbO) nanocrystals under resonant excitation at 976 nm is presented. The results showed that by increasing the pump power/intensity, a strong reduction is observed at the 800/480 nm emitted intensity ratio, characterizing what can be denominated as laser pump power-induced color tunability or luminescent switching. The physical origin is discussed with a focus on tailoring of luminescent switchers to operate at a large pump power range and, indeed, it is intrinsically associated with the competition of the two- and three-photon UC processes and with highly efficient UC emissions in the investigated material. The effect of Yb-ion concentration along with the theoretical aspects on luminescence switching has been investigated. The results obtained here could be useful in the field of sensors and networks for optical processing and optical communications.

  14. Erbium doping of lithium niobate by the ion exchange process for high-gain optical amplifiers

    NASA Astrophysics Data System (ADS)

    Caccavale, Frederico; Fedorov, Vyacheslav A.; Korkishko, Yuri N.; Morozova, Tamara V.; Sada, Cinzia; Segato, Francesco

    2000-04-01

    The erbium-lithium ion exchange is presented as a method for the erbium local doping of lithium niobate crystals. Ion exchange process is performed immersing the LiNbO3 substrates in a liquid melt, containing erbium ions; due to their high mobility, the lithium ions migrate from the crystal to the melt, and are replaced by erbium ions. A systematic analysis of the doping process is performed, and the influence of the process parameters is investigated: exchange time and temperature, crystal cut direction, composition and chemical reactivity of the Er ions liquid source. By structural (X-Ray Diffraction and Rutherford Backscattering Spectrometry), compositional (Secondary Ion Mass Spectrometry) and spectroscopic techniques (optical spectroscopy and micro-luminescence), the formation of lithium deficient phases and the incorporation of the Er ions into the LiNbO3 matrix is studied.

  15. Photo-luminescence studies of strontium barium niobate crystals doped with Cr 3+ ions

    NASA Astrophysics Data System (ADS)

    Han, T. P. J.; Jaque, F.; Jaque, D.; Ivleva, L.

    2006-01-01

    This paper reports the photo-luminescence spectroscopic results of Strontium-Barium-Niobate, Sr x,Ba 1- xNb 2O 5 (SBN, x = 0.61 for near congruent composition) crystals doped with Cr 2O, at cryogenic temperature (20 K). The experimental results reveal the need of re-assignment of the Cr 3+ ions defect centres in this material. For first time, a broad emission band in the near infrared region centred at ca. 950 nm is reported. This emission band has micro-seconds decaytime constant and a FWHM band-width > 1700 cm -1 and has been ascribed to the vibronically assisted 4T 2 → 4A 2 transition. A much narrower emission band centred at ca. 764 nm with milli-seconds decaytime constant and a FWHM band-width of ca. 170 cm -1 is correlated to the 2E → 4A 2 radiative transition (R-line).

  16. Formation of Nd 3+ doped Strontium Barium Niobate nanocrystals by two different methods

    NASA Astrophysics Data System (ADS)

    Haro-González, P.; Martín, L. L.; González-Pérez, S.; Martín, I. R.

    2010-08-01

    The study of two different methods to obtain Strontium Barium Niobate nanocrystals has been carried out. Previously, Nd 2O 3 doped SrO-BaO-Nb 2O 5-B 2O 3 glasses were fabricated using the melt quenching process. In the first method, a thermal treatment in an electrical furnace at 620 °C was used to obtain glass ceramic samples. In the second one, the nanocrystals were obtained under continuous Ar laser irradiation in a localized zone in the glass sample. The X-ray diffraction patterns confirmed the formation of SBN nanocrystals in both cases. The optical measurements indicate the incorporation of Nd 3+ ions into the nanocrystals which produces an increment of the luminescence intensity. Moreover, a calibration with the temperature has been carried out for the ratio of the Nd 3+ emissions. This result could let to control the temperature of the laser irradiated zone.

  17. Writing of rare-earth ion doped lithium niobate line patterns in glass by laser scanning

    NASA Astrophysics Data System (ADS)

    Honma, T.; Komatsu, T.; Zhao, D.; Jain, H.

    2009-02-01

    A glass of Er3+ doped Li2O-Nb2O5-SiO2-B2O3 with an addition of CuO or Sm2O3 crystallizing nonlinear optical lithium niobate LiNbO3 (LN) is developed. Crystalline lines of LN have been fabricated on the glass surface by continuous wave Yb fiber laser irradiations with a wavelength of 1080 nm. The laser written LN crystalline lines have been found, by means of electron back scattering method, micro-Raman and second harmonic experiments, to be well oriented along the laser scanning direction. For the testing of optical waveguides crystal lines exhibit light confinements due to the refractive index (n) changes between the patterned line (n~2.2) and the glass matrix (n=1.7). The analysis of the confocal micro-luminescence spectra obtained for the crystalline line indicates the incorporation of Er3+ ions into LN crystals.

  18. Electro-optically tunable, multi-wavelength optical parametric generators in aperiodically poled lithium niobates.

    PubMed

    Chen, Y H; Chung, H P; Chang, W K; Lyu, H T; Chang, J W; Tseng, C H

    2012-12-17

    We report on the design and demonstration of electro-optically tunable, multi-wavelength optical parametric generators (OPGs) based on aperiodically poled lithium niobate (APPLN) crystals. Two methods have been proposed to significantly enhance the electro-optic (EO) tunability of an APPLN OPG constructed by the aperiodic optical superlattice (AOS) technique. This is done by engineering the APPLN domain structure either in the crystal fabrication or in the crystal design process to increase the length or block-number difference of the two opposite-polarity domains used in the structure. Several orders of magnitude enhancement on the EO tuning rate of the APPLN OPGs constructed by the proposed techniques for simultaneous multiple signal wavelength generation over a conventional one has been demonstrated in a near infrared band (1500-1600 nm). PMID:23263140

  19. Observation of all-in type tetrahedral displacements in nonmagnetic pyrochlore niobates

    NASA Astrophysics Data System (ADS)

    Torigoe, S.; Ishimoto, Y.; Aoishi, Y.; Murakawa, H.; Matsumura, D.; Yoshii, K.; Yoneda, Y.; Nishihata, Y.; Kodama, K.; Tomiyasu, K.; Ikeda, K.; Nakao, H.; Nogami, Y.; Ikeda, N.; Otomo, T.; Hanasaki, N.

    2016-02-01

    We observed all-in type Nb tetrahedral displacement in nonmagnetic pyrochlore niobates A2Nb2O7 (A =Nd0.5Ca0.5 and Y0.5Ca0.5 ) through the analysis of the neutron pair distribution function and the extended x-ray absorption function spectroscopy. The all-in type Nb tetrahedral displacement, which has the character of a charge singlet state, is driven by the formation of the bonding orbital. The diffuse scattering in the x-ray diffraction, which has the resonant component in the Nb L3 edge, indicates that the all-in type Nb tetrahedral displacement has the periodicity with its short-range correlation.

  20. Lightwave Circuits in Lithium Niobate through Hybrid Waveguides with Silicon Photonics

    NASA Astrophysics Data System (ADS)

    Weigel, Peter O.; Savanier, Marc; Derose, Christopher T.; Pomerene, Andrew T.; Starbuck, Andrew L.; Lentine, Anthony L.; Stenger, Vincent; Mookherjea, Shayan

    2016-03-01

    We demonstrate a photonic waveguide technology based on a two-material core, in which light is controllably and repeatedly transferred back and forth between sub-micron thickness crystalline layers of Si and LN bonded to one another, where the former is patterned and the latter is not. In this way, the foundry-based wafer-scale fabrication technology for silicon photonics can be leveraged to form lithium-niobate based integrated optical devices. Using two different guided modes and an adiabatic mode transition between them, we demonstrate a set of building blocks such as waveguides, bends, and couplers which can be used to route light underneath an unpatterned slab of LN, as well as outside the LN-bonded region, thus enabling complex and compact lightwave circuits in LN alongside Si photonics with fabrication ease and low cost.

  1. A compact photonic crystal micro-cavity on a single-mode lithium niobate photonic wire

    NASA Astrophysics Data System (ADS)

    Cai, Lutong; Zhang, Shaomei; Hu, Hui

    2016-03-01

    The properties of the guided modes, including the single-mode conditions and the coupling of different polarized modes in the single-crystal lithium niobate photonic wires, were analyzed in detail. One-dimensional photonic crystal micro-cavities with several different patterns, which could be used as an ultra-compact optical filter, were designed and simulated in order to get high transmission at the resonant wavelength and the best preferment. The designed structure, with the whole size of 6.5 × 0.7 μm2, was fabricated on a single-mode photonic wire. A measured peak transmission of 0.34 at 1400 nm, an extinction ratio of 12.5 dB and a Q factor of 156 were obtained. The measured transmission spectrum was basically consistent with the simulation, although a slight shift of resonant wavelength occurred due to the fabrication errors.

  2. Iron-doped lithium niobate as a read-write holographic storage medium

    NASA Technical Reports Server (NTRS)

    Alphonse, G. A.; Phillips, W.

    1976-01-01

    The response of iron-doped lithium niobate under conditions corresponding to hologram storage and retrieval is described, and the material characteristics are discussed. The optical sensitivity can be improved by heavy chemical reduction of lightly doped crystals such that most of the iron is in the divalent state, the remaining part being trivalent. The best reduction process found to be reproducible so far is the anneal of the doped crystal in the presence of a salt such as lithium carbonate. It is shown by analysis and simulation that a page-oriented read-write holographic memory with 1000 bits per page would have a cycle time of about 60 msec and a signal-to-noise ratio of 27 dB. This cycle time, although still too long for a practical memory, represents an improvement of two orders of magnitude over that of previous laboratory prototypes using a thermoplastic storage medium

  3. Biocompatibility of ferroelectric lithium niobate and the influence of polarization charge on osteoblast proliferation and function.

    PubMed

    Carville, N Craig; Collins, Liam; Manzo, Michele; Gallo, Katia; Lukasz, Bart I; McKayed, Katey K; Simpson, Jeremy C; Rodriguez, Brian J

    2015-08-01

    In this work, the influence of substrate surface charge on in vitro osteoblast cell proliferation on ferroelectric lithium niobate (LN) crystal surfaces is investigated. LN has a spontaneous polarization along the z-axis and is thus characterized by positive and negative bound polarization charge at the +z and -z surfaces. Biocompatibility of LN was demonstrated via culturing and fluorescence imaging of MC3T3 osteoblast cells for up to 11 days. The cells showed enhanced proliferation rates and improved osteoblast function through mineral formation on the positively and negatively charged LN surfaces compared to electrostatically neutral x-cut LN and a glass cover slip control. These results highlight the potential of LN as a template for investigating the role of charge on cellular processes. PMID:25504748

  4. The photorefractive characteristics of bismuth-oxide doped lithium niobate crystals

    SciTech Connect

    Zheng, Dahuai; Yao, Jiaying; Kong, Yongfa; Liu, Shiguo; Zhang, Ling; Chen, Shaolin; Xu, Jingjun

    2015-01-15

    Bismuth-doped lithium niobate (LN:Bi) crystals were grown by Czochralski method and their optical damage resistance, photorefraction, absorption spectra, and defect energy levels were investigated. The experimental results indicate that the photorefractive properties of LN:Bi were enhanced as compared with congruent one, the photorefractive response time was greatly shortened, the photorefractive sensitivity was increased, and the diffraction efficiency of near-stoichiometric LN:Bi (SLN:Bi) reached 31.72% and 49.08% at 532 nm and 488 nm laser, respectively (light intensity of 400 mW/cm{sup 2}). An absorption peak at about 350 nm was observed in the absorption spectrum of LN:Bi. And the defect energy levels simulation indicates new defect levels appear in the forbidden gap of LN:Bi crystals. Therefore bismuth can act as photorefractive centers in LN crystals.

  5. Highly sensitive absorption measurements in lithium niobate using whispering gallery resonators

    NASA Astrophysics Data System (ADS)

    Leidinger, Markus; Buse, Karsten; Breunig, Ingo

    2015-02-01

    The absorption coefficient of undoped, congruently grown lithium niobate (LiNbO3) for ordinarily and extraordinarily polarized light is measured in the wavelength range from 390 to 2600 nm using whispering gallery resonators (WGRs). These monolithic cavities guide light by total internal reflection. Their high Q-factor provides several hundred meters of propagation for the coupled light in millimetre size resonators allowing for the measurement of absorption coefficients below 10-2 cm-1, where standard methods such as Fourier-transform or grating spectroscopy meet their limit. In this work the lowest measured value is 10-4 cm-1 at 1700 nm wavelength. Furthermore, the known OH- overtone at 1470 nm wavelength can be resolved clearly.

  6. A Novel Coupled Resonator Photonic Crystal Design in Lithium Niobate for Electrooptic Applications

    DOE PAGESBeta

    Ozturk, Birol; Yavuzcetin, Ozgur; Sridhar, Srinivas

    2015-01-01

    High-aspect-ratio photonic crystal air-hole fabrication on bulk Lithium Niobate (LN) substrates is extremely difficult due to its inherent resistance to etching, resulting in conical structures and high insertion losses. Here, we propose a novel coupled resonator photonic crystal (CRPC) design, combining a coupled resonator approach with that of Bragg gratings. CRPC design parameters were optimized by analytical calculations and FDTD simulations. CRPC structures with optimized parameters were fabricated and electrooptically tested on bulk LN annealed proton exchange waveguides. Low insertion loss and large electrooptic effect were observed with the fabricated devices, making the CRPC design a promising structure for electroopticmore » device applications.« less

  7. Integrated opto-microfluidics platforms in lithium niobate crystals for sensing applications

    NASA Astrophysics Data System (ADS)

    Bettella, G.; Pozza, G.; Zaltron, A.; Ciampolillo, M. V.; Argiolas, N.; Sada, C.; Chauvet, M.; Guichardaz, B.

    2015-02-01

    In micro-analytical chemistry and biology applications, droplet microfluidic technology holds great promise for efficient lab-on-chip systems where higher levels of integration of different stages on the same platform is constantly addressed. The possibility of integration of opto-microfluidic functionalities in lithium niobate (LiNbO3) crystals is presented. Microfluidic channels were directly engraved in a LiNbO3 substrate by precision saw cutting, and illuminated by optical waveguides integrated on the same substrate. The morphological characterization of the microfluidic channel and the optical response of the coupled optical waveguide were tested. In particular, the results indicate that the optical properties of the constituents dispersed in the fluid flowing in the microfluidic channel can be monitored in situ, opening to new compact optical sensor prototypes based on droplets generation and optical analysis of the relative constituents.

  8. Read-write holographic memory with iron-doped lithium niobate

    NASA Technical Reports Server (NTRS)

    Alphonse, G. A.; Phillips, W.

    1975-01-01

    The response of iron doped lithium niobate under conditions corresponding to hologram storage and retrieval is described, and the material's characteristics are discussed. The optical sensitivity can be improved by heavy chemical reduction of lightly doped crystals such that most of the iron is in the divalent state, the remaining part being trivalent. The best reduction process found to be reproducible so far is the anneal of the doped crystal in the presence of a salt such as lithium carbonate. It is shown by analysis and simulation that a page-oriented read-write holographic memory with 1,000 bits per page would have a cycle time of about 60 ms and a signal-to-noise ratio of 27 db. This cycle time, although still too long for a practical system, represents an improvement of two orders of magnitude over that of previous laboratory prototypes using different storage media.

  9. Polarization reversal induced by heating-cooling cycles in MgO doped lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Shur, V. Ya.; Mingaliev, E. A.; Lebedev, V. A.; Kuznetsov, D. K.; Fursov, D. V.

    2013-05-01

    Polarization reversal during heating-cooling cycles was investigated in MgO doped lithium niobate (MgO:LN) crystal using piezoresponse force microscopy. The essential dependence of the domain structure evolution scenario on the maximal temperature in the cycle has been revealed experimentally. It has been shown that the heating of the engineered domain matrix from room temperature to 85 °C leads to light size reduction of the isolated domains at the matrix edges, whereas the heating to 170 °C leads to essential reduction of the domain size. The opposite strong effect of the domain formation and growth during cooling after pulse heating have been revealed in single domain MgO:LN. The simulation of the time dependence of the pyroelectric field during heating-cooling cycle allowed to reveal the temperature hysteresis and to explain all observed effects taking into account the temperature dependence of the bulk conductivity.

  10. Fabrication of free-standing lithium niobate nanowaveguides down to 50 nm in width

    NASA Astrophysics Data System (ADS)

    Geiss, Reinhard; Sergeyev, Anton; Hartung, Holger; Solntsev, Alexander S.; Sukhorukov, Andrey A.; Grange, Rachel; Schrempel, Frank; Kley, Ernst-Bernhard; Tünnermann, Andreas; Pertsch, Thomas

    2016-02-01

    Nonlinear optical nanoscale waveguides are a compact and powerful platform for efficient wavelength conversion. The free-standing waveguide geometry opens a range of applications in microscopy for local delivery of light, where in situ wavelength conversion helps to overcome various wavelength-dependent issues, such as biological tissue damage. In this paper, we present an original patterning method for high-precision fabrication of free-standing nanoscale waveguides based on lithium niobate, a material with a strong second-order nonlinearity and a broad transparency window covering the visible and mid-infrared wavelength ranges. The fabrication process combines electron-beam lithography with ion-beam enhanced etching and produces nanowaveguides with lengths from 5 to 50 μm, widths from 50 to 1000 nm and heights from 50 to 500 nm, each with a precision of few nanometers. The fabricated nanowaveguides are tested in an optical characterization experiment showing efficient second-harmonic generation.

  11. Lithium niobate nanoparticle-coated Y-coupler optical fiber for enhanced electro-optic sensitivity.

    PubMed

    Rao, Ch N; Sagar, S B; Harshitha, N G; Aepuru, Radhamanohar; Premkumar, S; Panda, H S; Choubey, R K; Kale, S N

    2015-02-15

    Single crystals of lithium niobate (LiNbO3), possessing high birefringence and anisotropic properties have been explored, for a long time, to harness their excellent electro-optic properties. However, their nanoforms are comparatively less explored. In this context, dielectric constant and polarization (P) versus electric-field (E) characteristics of LiNbO3 nanomaterials have been studied. A nonideal P-E loop and a dielectric constant of 20 at the onset of 1 kHz were seen. The electro-optic sensitivity was found to be 4 times as compared to the bulk LiNbO3 crystals. The results are attributed to oxygen vacancies, antisite defects, and grain boundary effects in an already congruent structural matrix of LiNbO3. PMID:25680132

  12. Performance enhancement of nonlinear lithium niobate couplers via double titanium and magnesium diffusion

    NASA Astrophysics Data System (ADS)

    Prudenzano, F.; Ciminelli, C.; D'Orazio, A.; Petruzzelli, V.; Sario, M. De

    The effects of double Ti and Mg diffusion into lithium niobate couplers exploiting cascaded second-order nonlinearity are theoretically investigated. We demonstrate that this technology may be employed to optimize the performance of a new type of coupler made by uniaxial crystal having an unusual dielectric tensor configuration, i.e. equatorial. An extended version of the simple effective index method is developed in order to take into account the complex nature of hybrid modes. A home-made computer code is utilized in the electromagnetic analysis of rotated anisotropic channel waveguides. As an example, the simulation results show that a magnesium diffusion, made in the external region of a Ti : LiNbO 3 coupler which induces negative extraordinary and ordinary changes of the refractive indices of LiNbO 3 Δn e( Mg) =-0.002 and Δ no(Mg)=-0.001, decreases the linear coupling length from Lc=73 to 44 mm.

  13. Lightwave Circuits in Lithium Niobate through Hybrid Waveguides with Silicon Photonics

    DOE PAGESBeta

    Weigel, Peter O.; Savanier, Marc; DeRose, Christopher T.; Pomerene, Andrew T.; Starbuck, Andrew L.; Lentine, Anthony L.; Stenger, Vincent; Mookherjea, Shayan

    2016-03-01

    Here we demonstrate a photonic waveguide technology based on a two-material core, in which light is controllably and repeatedly transferred back and forth between sub-micron thickness crystalline layers of Si and LN bonded to one another, where the former is patterned and the latter is not. In this way, the foundry-based wafer-scale fabrication technology for silicon photonics can be leveraged to form lithium-niobate based integrated optical devices. Using two different guided modes and an adiabatic mode transition between them, we demonstrate a set of building blocks such as waveguides, bends, and couplers which can be used to route light underneathmore » an unpatterned slab of LN, as well as outside the LN-bonded region, thus enabling complex and compact lightwave circuits in LN alongside Si photonics with fabrication ease and low cost.« less

  14. Ferroelectric domain inversion and its stability in lithium niobate thin film on insulator with different thicknesses

    NASA Astrophysics Data System (ADS)

    Shao, Guang-hao; Bai, Yu-hang; Cui, Guo-xin; Li, Chen; Qiu, Xiang-biao; Geng, De-qiang; Wu, Di; Lu, Yan-qing

    2016-07-01

    Ferroelectric domain inversion and its effect on the stability of lithium niobate thin films on insulator (LNOI) are experimentally characterized. Two sets of specimens with different thicknesses varying from submicron to microns are selected. For micron thick samples (˜28 μm), domain structures are achieved by pulsed electric field poling with electrodes patterned via photolithography. No domain structure deterioration has been observed for a month as inspected using polarizing optical microscopy and etching. As for submicron (540 nm) films, large-area domain inversion is realized by scanning a biased conductive tip in a piezoelectric force microscope. A graphic processing method is taken to evaluate the domain retention. A domain life time of 25.0 h is obtained and possible mechanisms are discussed. Our study gives a direct reference for domain structure-related applications of LNOI, including guiding wave nonlinear frequency conversion, nonlinear wavefront tailoring, electro-optic modulation, and piezoelectric devices.

  15. Potassium dihydrogen phosphate and potassium tantalate niobate pyroelectric materials and far-infrared detectors

    SciTech Connect

    Baumann, H. B.

    1993-10-01

    This thesis discusses characterization of two ferroelectric materials and the fabrication of bolometers. Potassium tantalate niobate (KTN) and potassium dihydrogen phosphate (KDP) are chosen because they can be optimized for operation near 100K. Chap. 2 reviews the physics underlying pyroelectric materials and its subclass of ferroelectric materials. Aspects of pyroelectric detection are discussed in Chap. 3 including measurement circuit, noise sources, and effects of materials properties on pyroelectric response. Chap. 4 discusses materials selection and specific characteristics of KTN and KDP; Chap. 5 describes materials preparation; and Chap. 6 presents detector configuration and a thermal analysis of the pyroelectric detector. Electrical techniques used to characterize the materials and devices and results are discussed in Chap. 7 followed by conclusions on feasibility of KDP and KTN pyroelectric detectors in Chap. 8.

  16. Photoreduction of metal nanostructures on periodically proton exchanged MgO-doped lithium niobate crystals

    SciTech Connect

    Balobaid, Laila; Craig Carville, N.; Collins, Liam; Rodriguez, Brian J.; Manzo, Michele; Gallo, Katia

    2013-10-28

    Local reactivity on periodically proton exchanged lithium niobate (PPE:LN) surfaces is a promising route for the fabrication of regularly spaced nanostructures. Here, using MgO-doped PPE:LN templates, we investigate the influence of the doping on the nanostructure formation as a function of the proton exchange (PE) depth. The deposition is found to occur preferentially along the boundary between MgO-doped LN and the PE region when the PE depth is at least 1.73 μm, however, for shallower depths, deposition occurs across the entire PE region. The results are found to be consistent with an increased photoconductivity of the MgO-doped LN.

  17. Microscopy and microRaman study of periodically poled domains in deeply thinned lithium niobate wafers

    NASA Astrophysics Data System (ADS)

    Bullen, P. S.; Huang, H.-C.; Yang, H.; Dadap, J. I.; Kymissis, I.; Osgood, R. M.

    2016-07-01

    The domain structure of poled deeply thinned lithium niobate is investigated as a function of sample thickness. Free-standing samples of thickness from 25 to 500 μm are prepared by a multiple-cycle polish and annealing procedure and then periodically poled. Using these samples and employing micro-Raman scattering and scanning electron, atomic force, and optical microscopy together, the domain broadening and poling voltage are found to vary in a regular and significant manner. The poled domains show a reduction in width spreading of 38% as the sample thickness is reduced from 500 to 25 μm. Micro-Raman probe measurements verify the quality and the uniformity of the poled domains and provide insight into their thickness-dependent poling contrast.

  18. Lightwave Circuits in Lithium Niobate through Hybrid Waveguides with Silicon Photonics

    PubMed Central

    Weigel, Peter O.; Savanier, Marc; DeRose, Christopher T.; Pomerene, Andrew T.; Starbuck, Andrew L.; Lentine, Anthony L.; Stenger, Vincent; Mookherjea, Shayan

    2016-01-01

    We demonstrate a photonic waveguide technology based on a two-material core, in which light is controllably and repeatedly transferred back and forth between sub-micron thickness crystalline layers of Si and LN bonded to one another, where the former is patterned and the latter is not. In this way, the foundry-based wafer-scale fabrication technology for silicon photonics can be leveraged to form lithium-niobate based integrated optical devices. Using two different guided modes and an adiabatic mode transition between them, we demonstrate a set of building blocks such as waveguides, bends, and couplers which can be used to route light underneath an unpatterned slab of LN, as well as outside the LN-bonded region, thus enabling complex and compact lightwave circuits in LN alongside Si photonics with fabrication ease and low cost. PMID:26927022

  19. Quasi-phase matching via femtosecond laser-induced domain inversion in lithium niobate waveguides.

    PubMed

    Chen, Xin; Karpinski, Pawel; Shvedov, Vladlen; Boes, Andreas; Mitchell, Arnan; Krolikowski, Wieslaw; Sheng, Yan

    2016-06-01

    We demonstrate an all-optical fabrication method of quasi-phase matching structures in lithium niobate (LiNbO3) waveguides using a tightly focused femtosecond near-infrared laser beam (wavelength of 800 nm). In contrast to other all-optical schemes that utilize a periodic lowering of the nonlinear coefficient χ(2) by material modification, here the illumination of femtosecond pulses directly reverses the sign of χ(2) through the process of ferroelectric domain inversion. The resulting quasi-phase matching structures, therefore, lead to more efficient nonlinear interactions. As an experimental demonstration, we fabricate a structure with the period of 2.74 μm to frequency double 815 nm light. A maximum conversion efficiency of 17.45% is obtained for a 10 mm long waveguide. PMID:27244376

  20. Lightwave Circuits in Lithium Niobate through Hybrid Waveguides with Silicon Photonics.

    PubMed

    Weigel, Peter O; Savanier, Marc; DeRose, Christopher T; Pomerene, Andrew T; Starbuck, Andrew L; Lentine, Anthony L; Stenger, Vincent; Mookherjea, Shayan

    2016-01-01

    We demonstrate a photonic waveguide technology based on a two-material core, in which light is controllably and repeatedly transferred back and forth between sub-micron thickness crystalline layers of Si and LN bonded to one another, where the former is patterned and the latter is not. In this way, the foundry-based wafer-scale fabrication technology for silicon photonics can be leveraged to form lithium-niobate based integrated optical devices. Using two different guided modes and an adiabatic mode transition between them, we demonstrate a set of building blocks such as waveguides, bends, and couplers which can be used to route light underneath an unpatterned slab of LN, as well as outside the LN-bonded region, thus enabling complex and compact lightwave circuits in LN alongside Si photonics with fabrication ease and low cost. PMID:26927022

  1. Waveguides in single-crystal lithium niobate thin film by proton exchange.

    PubMed

    Cai, Lutong; Han, Shuang Li Huangpu; Hu, Hui

    2015-01-26

    The proton exchanged (PE) planar and channel waveguides in a 500 nm thick single-crystal lithium niobate thin film (lithium niobate on insulator, LNOI) were studied. The mature PE technique and strong confinement of light in the LN single-crystal thin film were used. The single mode and cut-off conditions of the channel waveguides were obtained by finite difference simulation. The results showed that the single mode channel waveguide would form if the width of the PE region was between 0.75 μm and 2.1 μm in the β(4) phase. The channel waveguide in LNOI had a much smaller mode size than that in the bulk material due to the high-refractive-index contrast. The mode size reached as small as 0.6 μm(2). in simulation. In the experiment, the refractive index and phase transition after PE in LNOI were analyzed using the prism coupling method and X-ray diffraction. Three different width waveguides (5 μm, 7 μm and 11 μm) were optically characterized. Near-field intensity distribution showed that their mode sizes were 3.3 μm(2).,5 μm(2). and 7 μm(2). The propagation losses were evaluated to be about 16 dB/cm, 12 dB/cm and 11 dB/cm, respectively. The results indicate that PE is a promising method for building more complicated photonic integrated circuits in single-crystal LN thin film. PMID:25835882

  2. Niobium-93 MQMAS NMR spectroscopic study of alkali and lead niobates.

    PubMed

    Prasad, S; Zhao, P; Huang, J; Fitzgerald, J J; Shore, J S

    2001-01-01

    93Nb (I = 9/2) multiple-quantum magic-angle spinning (MQMAS) NMR spectra of a series of inorganic niobates have been measured. 93Nb MQMAS spectroscopy yields spectra with typically an order of magnitude higher resolution than that obtainable with 93Nb MAS spectroscopy and 93Nb dynamic-angle spinning (DAS) spectroscopy. For example, the full-width at half-maximums of the 93Nb resonances of LiNbO3 were 9 (MAS), 5.8 (DAS), and 0.7 kHz (MQMAS). Broadening of the 93Nb MAS and DAS spectra is due to the second-order quadrupolar and homonuclear dipolar interactions, respectively. The quadrupolar products (P(O)) and isotropic chemical shifts (delta(iso)) of the 93Nb resonances of LiNbO3, NaNbO3, PbNb2O6, Pb2Nb2O7, Pb3Nb2O8, Pb3Nb4O15, Pb3Nb4O13, and Pb1.83Nb1.71Mg0.29O6.39 were determined from MQMAS spectra and range from 13.6 to 26.8 MHz and from -951 to -1113 ppm, respectively. Resonances with relatively large quadrupolar coupling constants (> 30 MHz) were not observed using MQMAS spectroscopy, but were detected using nutation spectroscopy. The applicability and limitations of MQMAS spectroscopy in studying inorganic niobates containing multiple 93Nb resonances are addressed and compared with those of MAS, nutation, and DAS spectroscopies. PMID:11407602

  3. Grace DAKASEP alkaline battery separator

    NASA Technical Reports Server (NTRS)

    Giovannoni, R. T.; Lundquist, J. T.; Choi, W. M.

    1987-01-01

    The Grace DAKASEP separator was originally developed as a wicking layer for nickel-zinc alkaline batteries. The DAKASEP is a filled non-woven separator which is flexible and heat sealable. Through modification of formulation and processing variables, products with a variety of properties can be produced. Variations of DAKASEP were tested in Ni-H2, Ni-Zn, Ni-Cd, and primary alkaline batteries with good results. The properties of DAKASEP which are optimized for Hg-Zn primary batteries are shown in tabular form. This separator has high tensile strength, 12 micron average pore size, relatively low porosity at 46-48 percent, and consequently moderately high resistivity. Versions were produced with greater than 70 percent porosity and resistivities in 33 wt percent KOH as low as 3 ohm cm. Performance data for Hg-Zn E-1 size cells containing DAKASEP with the properties shown in tabular form, are more reproducible than data obtained with a competitive polypropylene non-woven separator. In addition, utilization of active material is in general considerably improved.

  4. Alkaline detergent recycling via ultrafiltration

    SciTech Connect

    Steffani, C.; Meltzer, M.

    1995-06-01

    The metal finishing industry uses alkaline cleaners and detergents to remove oils and dirt from manufactured parts, often before they are painted or plated. The use of these cleaners has grown because environmental regulations are phasing out ozone depleting substances and placing restrictions on the use and disposal of many hazardous solvents. Lawrence Livermore National Laboratory is examining ultrafiltration as a cleaning approach that reclaims the cleaning solutions and minimizes wastes. The ultrafiltration membrane is made from sheets of polymerized organic film. The sheets are rolled onto a supporting frame and installed in a tube. Spent cleaning solution is pumped into a filter chamber and filtered through the membrane that captures oils and dirt and allows water and detergent to pass. The membrane is monitored and when pressure builds from oil and dirt, an automatic system cleans the surface to maintain solution flow and filtration quality. The results show that the ultrafiltration does not disturb the detergent concentration or alkalinity but removed almost all the oils and dirt leaving the solution in condition to be reused.

  5. Alkaline and alkaline earth metal phosphate halides and phosphors

    SciTech Connect

    Lyons, Robert Joseph; Setlur, Anant Achyut; Cleaver, Robert John

    2012-11-13

    Compounds, phosphor materials and apparatus related to nacaphite family of materials are presented. Potassium and rubidium based nacaphite family compounds and phosphors designed by doping divalent rare earth elements in the sites of alkaline earth metals in the nacaphite material families are descried. An apparatus comprising the phosphors based on the nacaphite family materials are presented herein. The compounds presented is of formula A.sub.2B.sub.1-yR.sub.yPO.sub.4X where the elements A, B, R, X and suffix y are defined such that A is potassium, rubidium, or a combination of potassium and rubidium and B is calcium, strontium, barium, or a combination of any of calcium, strontium and barium. X is fluorine, chlorine, or a combination of fluorine and chlorine, R is europium, samarium, ytterbium, or a combination of any of europium, samarium, and ytterbium, and y ranges from 0 to about 0.1.

  6. Probing the pseudo-1-D ion diffusion in lithium titanium niobate anode for Li-ion battery.

    PubMed

    Das, Suman; Dutta, Dipak; Araujo, Rafael B; Chakraborty, Sudip; Ahuja, Rajeev; Bhattacharyya, Aninda J

    2016-08-10

    Comprehensive understanding of the charge transport mechanism in the intrinsic structure of an electrode material is essential in accounting for its electrochemical performance. We present here systematic experimental and theoretical investigations of Li(+)-ion diffusion in a novel layered material, viz. lithium titanium niobate. Lithium titanium niobate (exact composition Li0.55K0.45TiNbO5·1.06H2O) is obtained from sol-gel synthesized potassium titanium niobate (KTiNbO5) by an ion-exchange method. The Li(+)-ions are inserted and de-inserted preferentially into the galleries between the octahedral layers formed by edge and corner sharing TiO6 and NbO6 octahedral units and the effective chemical diffusion coefficient, is estimated to be 3.8 × 10(-11) cm(2) s(-1) using the galvanostatic intermittent titration technique (GITT). Calculations based on density functional theory (DFT) strongly confirm the anisotropic Li(+)-ion diffusion in the interlayer galleries and that Li(+)-ions predominantly diffuse along the crystallographic b-direction. The preferential Li(+)-ion diffusion along the b-direction is assisted by line-defects, which are observed to be higher in concentration along the b-direction compared to the a- and c-directions, as revealed by high resolution electron microscopy. The Li-Ti niobate can be cycled to low voltages (≈0.2 V) and show stable and satisfactory battery performance over 100 cycles. Due to the possibility of cycling to low voltages, cyclic voltammetry and X-ray photoelectron spectroscopy convincingly reveal the reversibility of Ti(3+) ↔ Ti(2+) along with Ti(4+) ↔ Ti(3+) and Nb(5+) ↔ Nb(4+). PMID:27459636

  7. 3D pseudospectral time domain for modeling second-harmonic generation in periodically poled lithium niobate ridge-type waveguides

    NASA Astrophysics Data System (ADS)

    Devaux, Fabrice; Lantz, Eric; Chauvet, Mathieu

    2016-04-01

    We report an application of the tri-dimensional pseudo-spectral time domain algorithm, that solves with accuracy the nonlinear Maxwell's equations, to predict second harmonic generation in lithium niobate ridge-type waveguides with high index contrast. Characteristics of the nonlinear process such as conversion efficiency as well as impact of the multimode character of the waveguide are investigated as a function of the waveguide geometry in uniformly and periodically poled medium.

  8. Photo-induced morphological winding and unwinding motion of nanoscrolls composed of niobate nanosheets with a polyfluoroalkyl azobenzene derivative

    NASA Astrophysics Data System (ADS)

    Nabetani, Yu; Takamura, Hazuki; Uchikoshi, Akino; Hassan, Syed Zahid; Shimada, Tetsuya; Takagi, Shinsuke; Tachibana, Hiroshi; Masui, Dai; Tong, Zhiwei; Inoue, Haruo

    2016-06-01

    Photo-responsive nanoscrolls can be successfully fabricated by mixing a polyfluoroalkyl azobenzene derivative and a niobate nanosheet, which is exfoliated from potassium hexaniobate. In this study, we have found that the photo-responsive nanoscroll shows a morphological motion of winding and unwinding, which is basically due to the nanosheet sliding within the nanoscroll, by efficient photo-isomerization reactions of the intercalated azobenzene in addition to the interlayer distance change of the nanoscrolls. The relative nanosheet sliding of the nanoscroll is estimated to be ca. 280 nm from the AFM morphology analysis. The distance of the sliding motion is over 20 times that of the averaged nanosheet sliding in the azobenzene/niobate hybrid film reported previously. Photo-responsive nanoscrolls can be expected to be novel photo-activated actuators and artificial muscle model materials.Photo-responsive nanoscrolls can be successfully fabricated by mixing a polyfluoroalkyl azobenzene derivative and a niobate nanosheet, which is exfoliated from potassium hexaniobate. In this study, we have found that the photo-responsive nanoscroll shows a morphological motion of winding and unwinding, which is basically due to the nanosheet sliding within the nanoscroll, by efficient photo-isomerization reactions of the intercalated azobenzene in addition to the interlayer distance change of the nanoscrolls. The relative nanosheet sliding of the nanoscroll is estimated to be ca. 280 nm from the AFM morphology analysis. The distance of the sliding motion is over 20 times that of the averaged nanosheet sliding in the azobenzene/niobate hybrid film reported previously. Photo-responsive nanoscrolls can be expected to be novel photo-activated actuators and artificial muscle model materials. Electronic supplementary information (ESI) available: Fig. S1. Photo-isomerization reaction of nanoscrolls. See DOI: 10.1039/c6nr02177h

  9. All-optical format conversion using a periodically poled lithium niobate waveguide and a reflective semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Sun, Junqiang; Sun, Qizhen; Wang, Dalin; Zhou, Minjuan; Zhang, Xinliang; Huang, Dexiu; Fejer, M. M.

    2007-07-01

    In the present letter, the authors report on the realization of all-optical format conversion by using the cascaded sum- and difference-frequency generation in a periodically poled lithium niobate waveguide and the active mode locking in a reflective-semiconductor-optical-amplifier-based fiber ring laser. Tunable format conversions from nonreturn-to-zero pseudorandom binary sequence (PRBS) signal to return-to-zero PRBS idler at 10 and 20Gbit/s are observed in the experiment.

  10. Domain switching by electron beam irradiation of Z{sup +}-polar surface in Mg-doped lithium niobate

    SciTech Connect

    Shur, V. Ya. Chezganov, D. S.; Smirnov, M. M.; Alikin, D. O.; Neradovskiy, M. M.; Kuznetsov, D. K.

    2014-08-04

    The appearance of the static domains with depth above 200 μm in the bulk of MgO-doped lithium niobate single crystals as a result of focused electron beam irradiation of Z{sup +}-polar surface was demonstrated. The created domain patterns were visualized by high-resolution methods including piezoresponse force microscopy, scanning electron microscopy, and confocal Raman microscopy. The main stages of the domain structure formation were revealed and explained in terms of the original model.

  11. Hemoglobin niobate composite based biosensor for efficient determination of hydrogen peroxide in a broad pH range.

    PubMed

    Gao, Lu; Gao, Qiuming

    2007-02-15

    Inorganic layered niobates (HCa2Nb3O10) were used as immobilization matrices of hemoglobin (Hb) because of their tunable interlayer spaces, large surface areas and good biocompatibilities. A pair of well-defined, quasi-reversible cycle voltammertric peaks were obtained at the Hb-HCa2Nb3O10 modified pyrolytic graphite electrode, suggesting that the layered niobates facilitate the electron transfer between the proteins and the electrode. Hb-HCa2Nb3O10 modified electrode exhibited electrocatalytic response for monitoring H2O2 with a large linear detection range from 25 microM to 3.0 mM and a relatively high sensitivity of 172 microA mM-1 cm-2. Based on the stabilizing effect of the layered niobates, Hb-HCa2Nb3O10 modified electrode can detect H2O2 in strongly acidic and basic solutions with pH of 1-12, which greatly expands the application fields of biosensors. PMID:16887346

  12. Channel waveguides and y-junctions in x-cut single-crystal lithium niobate thin film.

    PubMed

    Cai, Lutong; Kong, Ruirui; Wang, Yiwen; Hu, Hui

    2015-11-01

    Proton exchanged channel waveguides in x-cut single-crystal lithium niobate thin film could avoid optical leakage loss which existed in the z-cut case. Indicated by simulations, the mechanism and condition of the optical leakage loss were studied. The light energy in the exchanged layer and the mode sizes were calculated to optimize the parameters for fabrication. By a very short time (3 minutes) proton exchange process without anneal, the channel waveguide with 2 μm width and 0.16 μm exchanged depth in the x-cut lithium niobate thin film had a propagation loss as low as 0.2 dB/cm at 1.55 μm. Furthermore, the Y-junctions based on the low-loss waveguide were designed and fabricated. For a Y-junction based on the 3 μm wide channel waveguide with 8000 μm bending radius, the total transmission could reach 85% ~90% and the splitting ratio maintained at a stable level around 1:1. The total length was smaller than 1 mm, much shorter than the conventional Ti-diffused and proton exchanged Y-junctions in bulk lithium niobate. PMID:26561191

  13. Determination of impurities in magnesium niobate by slurry introduction axially viewed inductively coupled plasma optical emission spectrometry.

    PubMed

    Wu, Dongmei; Qu, Haiyun; Dong, Min; Wang, Anbao; He, Pingang; Fang, Yuzhi

    2007-11-01

    A simple preparation scheme is described for the quantitative analysis of a magnesium niobate sample using slurry introduction axially viewed inductively coupled plasma optical emission spectrometry. Relationships between the stability of slurries and the conditions, such as particle size, pH, dispersant and amount of dispersant, were investigated experimentally. The MgNb(2)O(6) slurry sample was prepared by adding the dispersant sodium polyacrylate and agitation in an ultrasonic bath to ensure good dispersion. Under optimization of pH and amount of dispersant, an analysis of minor and trace impurities (Ba, Ca, Cr, Cu, Fe, Mn, Ni, Pb) in magnesium niobate was accomplished. Applying a paired t test, we showed that the results were in agreement at a 95% confidence level with the reference values obtained by a fusion method for a magnesium niobate sample, which verified that the calibration curves could be established by aqueous standards. Analytical results demonstrate that the factors that affected the accuracy of determination for MgNb(2)O(6) are mainly the particle size of the sample and the stability of slurry. PMID:17851651

  14. Process for extracting technetium from alkaline solutions

    SciTech Connect

    Moyer, B.A.; Sachleben, R.A.; Bonnesen, P.V.

    1994-12-31

    This invention relates generally to a process for extracting technetium from nuclear wastes and more particularly to a process for extracting technetium from alkaline waste solutions containing technetium and high concentrations of alkali metal nitrates. A process for extracting technetium values from an aqueous alkaline solution containing at least one alkali metal hydroxide and at least one alkali metal nitrate comprises the steps of: contacting the aqueous alkaline solution with a solvent consisting of a crown ether in a diluent, the diluent being a water-immiscible organic liquid in which the crown ether is soluble, for a period of time sufficient to selectively extract the technetium values from the aqueous alkaline solution into the solvent; separating the solvent containing the technetium values from the aqueous alkaline solution; and stripping the technetium values from the solvent by contacting the solvent with water.

  15. Alkaline-resistance model of subtilisin ALP I, a novel alkaline subtilisin.

    PubMed

    Maeda, H; Mizutani, O; Yamagata, Y; Ichishima, E; Nakajima, T

    2001-05-01

    The alkaline-resistance mechanism of the alkaline-stable enzymes is not yet known. To clarify the mechanism of alkaline-resistance of alkaline subtilisin, structural changes of two typical subtilisins, subtilisin ALP I (ALP I) and subtilisin Sendai (Sendai), were studied by means of physicochemical methods. Subtilisin NAT (NAT), which exhibits no alkaline resistance, was examined as a control. ALP I gradually lost its activity, accompanied by protein degradation, but, on the contrary, Sendai was stable under alkaline conditions. CD spectral measurements at neutral and alkaline pH indicated no apparent differences between ALP I and Sendai. A significant difference was observed on measurement of fluorescence emission spectra of the tryptophan residues of ALP I that were exposed on the enzyme surface. The fluorescence intensity of ALP I was greatly reduced under alkaline conditions; moreover, the reduction was reversed when alkaline-treated ALP I was neutralized. The fluorescence spectrum of Sendai remained unchanged. The enzymatic and optical activities of NAT were lost at high pH, indicating a lack of functional and structural stability in an alkaline environment. Judging from these results, the alkaline resistance is closely related to the surface structure of the enzyme molecule. PMID:11328588

  16. Inorganic-organic separators for alkaline batteries

    NASA Technical Reports Server (NTRS)

    Sheibley, D. W. (Inventor)

    1978-01-01

    A flexible separator is reported for use between the electrodes of Ni-Cd and Ni-Zn batteries using alkaline electrolytes. The separator was made by coating a porous substrate with a battery separator composition. The coating material included a rubber-based resin copolymer, a plasticizer and inorganic and organic fillers which comprised 55% by volume or less of the coating as finally dried. One or more of the filler materials, whether organic or inorganic, is preferably active with the alkaline electrolyte to produce pores in the separator coating. The plasticizer was an organic material which is hydrolyzed by the alkaline electrolyte to improve conductivity of the separator coating.

  17. Process for extracting technetium from alkaline solutions

    DOEpatents

    Moyer, Bruce A.; Sachleben, Richard A.; Bonnesen, Peter V.

    1995-01-01

    A process for extracting technetium values from an aqueous alkaline solution containing at least one alkali metal hydroxide and at least one alkali metal nitrate, the at least one alkali metal nitrate having a concentration of from about 0.1 to 6 molar. The solution is contacted with a solvent consisting of a crown ether in a diluent for a period of time sufficient to selectively extract the technetium values from the aqueous alkaline solution. The solvent containing the technetium values is separated from the aqueous alkaline solution and the technetium values are stripped from the solvent.

  18. Alkaline sorbent injection for mercury control

    DOEpatents

    Madden, Deborah A.; Holmes, Michael J.

    2002-01-01

    A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

  19. Alkaline sorbent injection for mercury control

    DOEpatents

    Madden, Deborah A.; Holmes, Michael J.

    2003-01-01

    A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

  20. Localized desvitrifiation in Er3+-doped strontium barium niobate glass by laser irradiation

    NASA Astrophysics Data System (ADS)

    Haro-González, P.; Martin, I. R.; Lahoz, F.; González-Pérez, S.; Capuj, N. E.; Jaque, D.

    2008-12-01

    Localized desvitrifiation in strontium barium niobate glass doped with Er3+ under laser irradiation has been carried out. The samples of this study have been fabricated by the melt quenching method and doped with 5% mol of Er3+. A 1.5-W cw Ar laser was focused on the sample to obtain desvitrifiation of the glass. Evidence of the changes induced by the Ar laser has been observed through the analysis of the photoluminescence of the Er3+ ions. The transitions corresponding to 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 have been studied to analyze structure changes. Microluminescence measurements have been carried out to spatially select positions inside and outside the irradiated area. We have observed changes in the emission bands corresponding to these transitions. The emission bands from Er3+ ions in the irradiated zone show a resolved structure while they are broadened outside that area. These changes in the optical properties of the Er3+ ions indicate that the Ar-laser irradiation has produced a change in the local structure of the material. These results show that a localized desvitrifiation has been produced after the laser action and the transition from glass to glass ceramic has been completed.

  1. Electric field controlled higher-order diffraction images of paraelectric potassium lithium tantalate niobate

    NASA Astrophysics Data System (ADS)

    Gong, Dewei; Chen, Changqing; Tian, Hao; Zhou, Zhongxiang

    2012-09-01

    We report some electric field controlled photorefractive higher-order diffraction phenomena of a paraelectric phase potassium lithium tantalate niobate crystal doped with iron. In experiments, a p-polarized semiconductor laser (532 nm) was used to record grating at a small incident angle. Higher-order diffraction images were observed when the signal beam was focused behind and in front of the crystal. Then the higher-order diffraction images were reconstructed by a p-polarized He-Ne laser (632.8 nm) in the direction perpendicular to the surface. The higher-order diffraction images could be controlled by the external electric field. A theory about the higher-order diffraction images of the K and 2K grating is developed. The results show that the even order diffraction images of the K grating and the odd order diffraction of the 2K grating overlap each other. The odd order diffraction images of the K grating are diffracted in unattached direction. The electric field controlled higher-order diffraction image provides a useful method for optical information processing.

  2. Resistance degradation due to interstitial hydrogen in photorefractive potassium lithium tantalate niobate single crystals

    NASA Astrophysics Data System (ADS)

    Ivker, M.; Agranat, A. J.

    2004-12-01

    Resistance degradation in potassium lithium tantalate niobate (KLTN) doped with iron and titanium was measured in a single sample containing various concentrations of interstitial hydrogen. In this crystal the degradation arose from the migration of interstitial hydrogen and not oxygen vacancies, as reported in previous research. Interstitial hydrogen and oxygen vacancy defects both arise to compensate the valence shortfall of the substitutional iron impurities and the thermodynamic balance between the two compensation mechanisms can be controlled using reaction chemistry techniques. Through appropriate annealing treatments a single crystal of KLTN was prepared in three states: hydrogen-rich oxidized, hydrogen-poor reduced, and hydrogen-rich reduced. The characteristic degradation times for the three cases were 29, 2710, and 26min, respectively. The degradation rate is correlated with hydrogen concentration and not oxidation state of the crystal. Infrared absorption from near the two electrodes of the hydrogen-rich reduced crystal after degradation confirmed polarization of the hydrogen concentration. Electrocoloration was also found to correlate with hydrogen—it was observed in both hydrogen-rich states, but was absent from the hydrogen-poor crystal.

  3. Investigation of pyroelectric electron emission from monodomain lithium niobate single crystals

    NASA Astrophysics Data System (ADS)

    Bourim, El Mostafa; Moon, Chang-Wook; Lee, Seung-Woon; Kyeong Yoo, In

    2006-09-01

    The behaviors of thermally stimulated electron emission from pyroelectric monodomain lithium niobate single crystal (LiNbO 3) were investigated by utilizing a Si p-n junction photodiode as electron detector and a receptive electron beam resist (E-beam resist) as electron collector. In high vacuum (10 -6 Torr), the pyroelectric electron emission (PEE) was found to depend on the exposed emitting polar crystal surface (+ Z face or - Z face) and was significantly influenced by the emitter-electron receiver gap distances. Thus, the PEE from + Z face was detected during heating and was activated, in small gaps (<2 mm), by field emission effect on which was superposed an intense field ionization effect that primed intermittent runway ionizations (plasma breakdown into a glow discharge). In large gaps (>2 mm) the emission was simply mastered by field emission effect. Whereas, The PEE from - Z face was detected during cooling and was solely due to the field ionization effect. Therewith, for small gaps (<2 mm) the emission was governed by intermittent runway ionization ignitions resulting from a high ionization degree leading to dense plasma formation, and for large gaps (>2 mm) PEE was governed by field ionization generating a soft and continuous plasma ambient atmosphere. Significant decrease of electron emission current was observed from + Z face after successive thermal cycles. A fast and fully emission recovery was established after a brief exposure of crystal to a poor air vacuum of 10 -1 Torr.

  4. Strong effect of low-dimensional Fe-doped cobalt niobate on a strongly ferrimagnetic system

    NASA Astrophysics Data System (ADS)

    Nlebedim, Cajetan; Jiles, David

    2015-03-01

    In this work, the first investigation of the effect of Fe-doped cobalt niobate (CoNb2O6) imbedded in the matrix of a strongly ferrimagnetic cobalt-iron oxide, is presented. The temperature dependence of the magnetic properties and how they change with variations in the concentration of CoNb2O6 is also presented. CoNb2O6 is a prototypical low-dimensional material belonging to the pyrochlore-type AB2O6 systems. Its low-dimensional magnetic characteristics can help in understanding the magnetic properties of higher order systems. It has been investigated for applications in resonators and capacitors. This work shows that the magnetization of the ferrimagnetic phase is strongly affected by the concentration of Co ions in the low-dimensional phase, below 15 K but changes in coercivity with temperature were predominantly due to the ferrimagnetic phase. The systematic variation in the concentration of both phases and the cation ratio in each phase, enable us to understand the variation of the magnetic properties with temperature. This work provides useful insights into tuning the magnetism in strongly magnetic materials with transition metal AB2O6 systems imbedded in their matrices. This work was supported by the USDoE, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division. The research was performed at Ames Laboratory, operated for the USDoE by Iowa State University (Contract # DE-AC02-07CH11358).

  5. Characterization of strontium barium niobate optical thin film grown by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Liu, H.; Li, S.; Fernandez, F. E.; Jia, W.; Liu, G.

    1999-12-01

    Optical quality thin films of strontium barium niobate SrxBa1-xNb2O6 either undoped or Eu3+-doped has been successfully grown on fused quartz substrates using pulsed laser deposition (PLD) technique. The optical properties were characterized in either time domain or in frequency domain. Undoped SBN thin films show a broad-band emission at UV, extending to the visible, which attributes to the exciton luminescence of the SBN host in the film. High-resolution nonlinear optical response in the picosecond region, as well as the third-order susceptibility were characterized by degenerate four-wave-mixing (DFWM) measurements. A considerable enhancement, by 2 orders of magnitude, of the third order nonlinear susceptibility χ(3) in transverse alignment was observed with respect to the bulk values. Eu3+-doped SBN films show a significant change in optical properties with annealing process. The fine structure of 5D0 to 7F multiplet emission was well resolved in the annealed sample. In a hole-burning experiment, a hole of width 100 MHz with depth as high as 30% was burnt using laser pumping at 5774 Å. It is suggested that Eu3+ ions may substitute Nb, occupying 6-fold sites.

  6. Characterization of strontium barium niobate optical thin film grown by pulsed laser deposition

    SciTech Connect

    Liu, H.; Fernandez, F. E.; Jia, W.; Li, S.; Liu, G.

    1999-12-02

    Optical quality thin films of strontium barium niobate Sr{sub x}Ba{sub 1-x}Nb{sub 2}O{sub 6} either undoped or Eu{sup 3+}-doped has been successfully grown on fused quartz substrates using pulsed laser deposition (PLD) technique. The optical properties were characterized in either time domain or in frequency domain. Undoped SBN thin films show a broad-band emission at UV, extending to the visible, which attributes to the exciton luminescence of the SBN host in the film. High-resolution nonlinear optical response in the picosecond region, as well as the third-order susceptibility were characterized by degenerate four-wave-mixing (DFWM) measurements. A considerable enhancement, by 2 orders of magnitude, of the third order nonlinear susceptibility {chi}{sup (3)} in transverse alignment was observed with respect to the bulk values. Eu{sup 3+}-doped SBN films show a significant change in optical properties with annealing process. The fine structure of {sup 5}D{sub 0} to {sup 7}F multiplet emission was well resolved in the annealed sample. In a hole-burning experiment, a hole of width 100 MHz with depth as high as 30% was burnt using laser pumping at 5774 A. It is suggested that Eu{sup 3+} ions may substitute Nb, occupying 6-fold sites.

  7. Structural changes induced on strontium barium niobate glass by femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Haro-González, P.; Martín, I. R.; González-Pérez, S.; Martin, L. L.; Lahoz, F.; Puerto, D.; Solís, J.

    2010-03-01

    Localized modification of the optical properties of erbium doped strontium barium niobate (SBN) glass has been performed using femtosecond laser irradiation. The samples, with composition SrO-BaO-Nb2O5-B2O5 and doped with 5%mol of Er3+, were fabricated using a melt-quenching method. The samples were irradiated with different number of pulses per spot (1-50 pulses) at two different laser fluences (2.6 and 5.6 J/cm2) by using an fs laser amplifier operating at 800 nm and generating pulses with a duration of 120 fs. Micro-luminescent microscopy, using an Ar+ laser as excitation source, has been used to analyze the modifications of the luminescent properties of the sample upon fs laser exposure. The emissions of the Er3+: 4I11/2→4I15/2 and 4I13/2→4I15/2 transitions allow appreciating the structural modifications caused by femtosecond laser exposure. The lifetimes of the levels involved in these transitions were measured inside and outside the laser irradiated region. These measurements have been compared with those obtained in bulk glass ceramic sample, which is obtained from the glass precursor by a thermal treatment in order to estimate the optimal conditions to produce nanocrystals in a localized region by ultrafast laser irradiation.

  8. Influence of annealing on the photodeposition of silver on periodically poled lithium niobate

    NASA Astrophysics Data System (ADS)

    Carville, N. Craig; Neumayer, Sabine M.; Manzo, Michele; Baghban, Mohammad-Amin; Ivanov, Ilia N.; Gallo, Katia; Rodriguez, Brian J.

    2016-02-01

    The preferential deposition of metal nanoparticles onto periodically poled lithium niobate surfaces, whereby photogenerated electrons accumulate in accordance with local electric fields and reduce metal ions from solution, is known to depend on the intensity and wavelength of the illumination and the concentration of the solution used. Here, it is shown that for identical deposition conditions (wavelength, intensity, concentration), post-poling annealing for 10 h at 200 °C modifies the surface reactivity through the reorientation of internal defect fields. Whereas silver nanoparticles deposit preferentially on the +z domains on unannealed crystals, the deposition occurs preferentially along 180° domain walls for annealed crystals. In neither case is the deposition selective; limited deposition occurs also on the unannealed -z domain surface and on both annealed domain surfaces. The observed behavior is attributed to a relaxation of the poling-induced defect frustration mediated by Li+ ion mobility during annealing, which affects the accumulation of electrons, thereby changing the surface reactivity. The evolution of the defect field with temperature is corroborated using Raman spectroscopy.

  9. Disordered lithium niobate rock-salt materials prepared by hydrothermal synthesis.

    PubMed

    Modeshia, Deena R; Walton, Richard I; Mitchell, Martin R; Ashbrook, Sharon E

    2010-07-14

    An investigation of the one-step hydrothermal crystallisation of lithium niobates reveals that reaction between Nb(2)O(5) and aqueous LiOH at 240 degrees C yields materials with a disordered rock-salt structure where the metals are statistically distributed over the cation sites. This contrasts with the well-studied reaction between Nb(2)O(5) and NaOH or KOH that produces ANbO(3) (A = Na, K) perovskites. Powder neutron diffraction shows that materials prepared at short reaction times and lower LiOH concentration (2.5 M) are lithium deficient and have a slight excess of niobium, but that at longer periods of reaction in 5 M LiOH, close to the ideal, stoichiometric Li(0.75)Nb(0.25)O composition is produced. Upon annealing this phase cleanly transforms into the known ordered rock-salt material Li(3)NbO(4), a process we have followed using thermodiffractometry, which indicates that transformation begins at approximately 700 degrees C. Solid-state (93)Nb and (7)Li NMR of the disordered and ordered rock-salt phases shows that both contain single metal sites but there is clear evidence for local disorder in the disordered samples. For the ordered material, NMR parameters derived from experiment are also compared to those calculated using density functional theory and are shown to be in good agreement. PMID:20442945

  10. Thickness, humidity, and polarization dependent ferroelectric switching and conductivity in Mg doped lithium niobate

    SciTech Connect

    Neumayer, Sabine M.; Strelcov, Evgheni; Manzo, Michele; Gallo, Katia; Kravchenko, Ivan I.; Kholkin, Andrei L.; Kalinin, Sergei V.; Rodriguez, Brian J.

    2015-12-28

    Mg doped lithium niobate (Mg:LN) exhibits several advantages over undoped LN such as resistance to photorefraction, lower coercive fields, and p-type conductivity that is particularly pronounced at domain walls and opens up a range of applications, e.g., in domain wall electronics. Engineering of precise domain patterns necessitates well founded knowledge of switching kinetics, which can differ significantly from that of undoped LN. In this work, the role of humidity and sample composition in polarization reversal has been investigated under application of the same voltage waveform. Control over domain sizes has been achieved by varying the sample thickness and initial polarization as well as atmospheric conditions. Additionally, local introduction of proton exchanged phases allows for inhibition of domain nucleation or destabilization, which can be utilized to modify domain patterns. In polarization dependent current flow, attributed to charged domain walls and band bending, it the rectifying ability of Mg: LN in combination with suitable metal electrodes that allow for further tailoring of conductivity is demonstrated.