WorldWideScience

Sample records for niobate ferroelectric crystals

  1. Influence of UV light and heat on the ferroelectric properties of lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Steigerwald, Hendrik

    2011-08-15

    One of the most important non-linear-optical materials is lithium niobate, due to its ease of fabrication, robustness, transparency in the visible-to-infrared and excellent nonlinear properties. In this thesis the issue of tailoring ferroelectric domain structures in lithium niobate crystals is approached from two sides: interaction of defect structures inside the crystal with growing ferroelectric domains is investigated and also actual domain patterning on all crystal faces by different methods is performed. Special emphasis is given to the Mg-doped material. The fundamental understanding and the methods of domain patterning developed in this thesis are then used to obtain tailored domain structures that meet the requirements of their intended application in non-linear optics. (orig.)

  2. Ferroelectric lead magnesium niobate-lead titanate single crystals for ultrasonic hydrophone applications

    International Nuclear Information System (INIS)

    Lau, S.T.; Lam, K.H.; Chan, H.L.W.; Choy, C.L.; Luo, H.S.; Yin, Q.R.; Yin, Z.W.

    2004-01-01

    Ferroelectric lead magnesium niobate-lead titanate (PMN-PT) single crystals with a composition around the rhombohedral-tetragonal morphotropic phase boundary (65 mol% of PMN) were used to fabricate single-element needle-type hydrophones for measuring the spatial and temporal characteristics of medical ultrasonic transducers. PMN-PT single crystal was grown by a modified Bridgman method. Discs (0.5 mm thick) with normal along the direction were cut and then poled by a dc field in the thickness direction. The single crystal has a high relative permittivity (ε r ∼4000) making it appropriate for small area hydrophone applications. Single-element needle-type hydrophones with this material as the sensing element have been fabricated and characterized. The hydrophones have flat frequency response and good receiving sensitivity over certain frequency range in the megahertz region

  3. Pyroelectric field assisted ion migration induced by ultraviolet laser irradiation and its impact on ferroelectric domain inversion in lithium niobate crystals

    International Nuclear Information System (INIS)

    Ying, C. Y. J.; Mailis, S.; Daniell, G. J.; Steigerwald, H.; Soergel, E.

    2013-01-01

    The impact of UV laser irradiation on the distribution of lithium ions in ferroelectric lithium niobate single crystals has been numerically modelled. Strongly absorbed UV radiation at wavelengths of 244–305 nm produces steep temperature gradients which cause lithium ions to migrate and result in a local variation of the lithium concentration. In addition to the diffusion, here the pyroelectric effect is also taken into account which predicts a complex distribution of lithium concentration along the c-axis of the crystal: two separated lithium deficient regions on the surface and in depth. The modelling on the local lithium concentration and the subsequent variation of the coercive field are used to explain experimental results on the domain inversion of such UV treated lithium niobate crystals

  4. Piezoelectric and ferroelectric properties of lead-free niobium-rich potassium lithium tantalate niobate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jun, E-mail: lijuna@hit.edu.cn [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Li, Yang [Department of chemistry, Harbin Institute of Technology, Harbin 150001 (China); Zhou, Zhongxiang [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Guo, Ruyan; Bhalla, Amar S. [Multifunctional Electronic Materials and Device Research Lab, Department of Electrical and Computer Engineering, The University of Texas at San Antonio, San Antonio 78249 (United States)

    2014-01-01

    Graphical abstract: - Highlights: • Lead-free K{sub 0.95}Li{sub 0.05}Ta{sub 1−x}Nb{sub x}O{sub 3} single crystals were grown using the top-seeded melt growth method. • The piezoelectric and ferroelectric properties of as-grown crystals were systematically investigated. • The piezoelectric properties are very attractive, e.g. for x = 0.60 composition, k{sub t} ≈ 70%, k{sub 31} ≈ 70%, k{sub 33} ≈ 77%, d{sub 31} ≈ 230 pC/N, d{sub 33} ≈ 600 pC/N. • The coercive fields of P–E hysteresis loops are quite small, about or less than 1 kV/mm. - Abstract: Lead-free potassium lithium tantalate niobate single crystals with the composition of K{sub 0.95}Li{sub 0.05}Ta{sub 1−x}Nb{sub x}O{sub 3} (abbreviated as KLTN, x = 0.51, 0.60, 0.69, 0.78) were grown using the top-seeded melt growth method. Their piezoelectric and ferroelectric properties in as-grown crystals have been systematically investigated. The phase transitions and Curie temperatures were determined from dielectric and pyroelectric measurements. Piezoelectric coefficients and electromechanical coupling factors in thickness mode, length-extensional mode and longitudinal mode were obtained. The piezoelectric properties are very attractive, e.g. for x = 0.60 composition, k{sub t} ≈ 70%, k{sub 31} ≈ 70%, k{sub 33} ≈ 77%, d{sub 31} ≈ 230 pC/N, d{sub 33} ≈ 600 pC/N are comparable to the lead-based PZT composition. The polarization versus electric field hysteresis loops show saturated shapes. In short, lead-free niobium-rich KLTN system possesses comparable properties to those in important lead-based piezoelectric material nowadays.

  5. Ar-ion etching effects on the XPS spectra of the ferroelectric potassium lithium niobate crystal

    International Nuclear Information System (INIS)

    Jun, Byeong-Eog; Kim, Chung-Sik; Kim, Hyung-Kook; Kim, Jung-Nam; Hwang, Yoon-Hwae; Chae, Jong-Suk

    2005-01-01

    Ar + -ion-sputtered surface of KLN crystal was studied by X-ray photoelectron spectroscopy in order to investigate the oxidation states and chemical environments of K, Li, Nb and O ions. As Ar + -sputtering time increased, the decreasing binding energy of Nb 3d and the peak broadening of mixed Nb 4s and Li 1s (namely Nb* 4s) levels were observed. Also, the binding-energy difference between O 1s and Nb* 4s increased as Ar + -ion-sputtering time increased. The broad peak of Nb* 4s was considered to be related to the site occupancy of Li ion in A1 and C in tetragonal tungsten-bronze structure.

  6. Lithium niobate. Defects, photorefraction and ferroelectric switching

    Energy Technology Data Exchange (ETDEWEB)

    Volk, Tatyana [Russian Academy of Sciences, Inst. for Crystallography, Moscow (Russian Federation); Woehlecke, Manfred [Osnabrueck Univ. (Germany). Fachbereich Physik

    2008-07-01

    The book presents the current state of studies of point defects, both intrinsic and extrinsic (impurities, radiation centers, etc.), in LiNbO{sub 3}. The contribution of intrinsic defects to photoinduced charge transport, i.e. to the photorefraction, is explained. The photorefractive and optical properties of LiNbO{sub 3} crystals with different stoichiometry and of those doped with so-called ''optical-damage resistant'' impurities controlling the intrinsic defect structure are described in detail. Applications included are to the problem of non-erasable recording of photorefractive holograms in LiNbO{sub 3} and the current situation of studies in the ferroelectric switching and domain structure of LiNbO{sub 3}, as well as the creation of periodically-poled structures for the optical frequency conversion. (orig.)

  7. Radiation-damage-assisted ferroelectric domain structuring in magnesium-doped lithium niobate

    Science.gov (United States)

    Jentjens, L.; Peithmann, K.; Maier, K.; Steigerwald, H.; Jungk, T.

    2009-06-01

    Irradiation of 5% magnesium-doped lithium niobate crystals (LiNbO3:Mg) with high-energy, low-mass 3He ions, which are transmitted through the crystal, changes the domain reversal properties of the material. This enables easier domain engineering compared to non-irradiated material and assists the formation of small-sized periodically poled domains in LiNbO3:Mg. Periodic domain structures exhibiting a width of ≈520 nm are obtained in radiation-damaged sections of the crystals. The ferroelectric poling behavior between irradiated and non-treated material is compared.

  8. Optical cleaning of lithium niobate crystals

    International Nuclear Information System (INIS)

    Koesters, Michael

    2010-01-01

    An all-optical method for the removal of photoexcitable electrons from photorefractive centers to get rid of optical damage in lithium niobate crystals is presented, the so-called ''optical cleaning''. The method combines the photovoltaic drift of electrons with ionic charge compensation at sufficiently high temperatures of about 180 C. Optimum choice of the light pattern plus heat dramatically decreases the concentration of photoexcitable electrons in the exposed region leading to a suppression of optical damage. Experiments with slightly iron-doped lithium niobate crystals have shown an increase of the threshold for optical damage of more than 1000 compared to those of untreated crystals. (orig.)

  9. Optical cleaning of lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Koesters, Michael

    2010-01-15

    An all-optical method for the removal of photoexcitable electrons from photorefractive centers to get rid of optical damage in lithium niobate crystals is presented, the so-called ''optical cleaning''. The method combines the photovoltaic drift of electrons with ionic charge compensation at sufficiently high temperatures of about 180 C. Optimum choice of the light pattern plus heat dramatically decreases the concentration of photoexcitable electrons in the exposed region leading to a suppression of optical damage. Experiments with slightly iron-doped lithium niobate crystals have shown an increase of the threshold for optical damage of more than 1000 compared to those of untreated crystals. (orig.)

  10. III-nitride integration on ferroelectric materials of lithium niobate by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Namkoong, Gon; Lee, Kyoung-Keun; Madison, Shannon M.; Henderson, Walter; Ralph, Stephen E.; Doolittle, W. Alan

    2005-01-01

    Integration of III-nitride electrical devices on the ferroelectric material lithium niobate (LiNbO 3 ) has been demonstrated. As a ferroelectric material, lithium niobate has a polarization which may provide excellent control of the polarity of III-nitrides. However, while high temperature, 1000 deg. C, thermal treatments produce atomically smooth surfaces, improving adhesion of GaN epitaxial layers on lithium niobate, repolarization of the substrate in local domains occurs. These effects result in multi domains of mixed polarization in LiNbO 3 , producing inversion domains in subsequent GaN epilayers. However, it is found that AlN buffer layers suppress inversion domains of III-nitrides. Therefore, two-dimensional electron gases in AlGaN/GaN heterojunction structures are obtained. Herein, the demonstration of the monolithic integration of high power devices with ferroelectric materials presents possibilities to control LiNbO 3 modulators on compact optoelectronic/electronic chips

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

    Science.gov (United States)

    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.

  12. Investigation of the cluster formation in lithium niobate crystals by computer modeling method

    Energy Technology Data Exchange (ETDEWEB)

    Voskresenskii, V. M.; Starodub, O. R., E-mail: ol-star@mail.ru; Sidorov, N. V.; Palatnikov, M. N. [Russian Academy of Sciences, Tananaev Institute of Chemistry and Technology of Rare Earth Elements and Mineral Raw Materials, Kola Science Centre (Russian Federation)

    2017-03-15

    The processes occurring upon the formation of energetically equilibrium oxygen-octahedral clusters in the ferroelectric phase of a stoichiometric lithium niobate (LiNbO{sub 3}) crystal have been investigated by the computer modeling method within the semiclassical atomistic model. An energetically favorable cluster size (at which a structure similar to that of a congruent crystal is organized) is shown to exist. A stoichiometric cluster cannot exist because of the electroneutrality loss. The most energetically favorable cluster is that with a Li/Nb ratio of about 0.945, a value close to the lithium-to-niobium ratio for a congruent crystal.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nava, G.; Minzioni, P.; Cristiani, I.; Degiorgio, V. [Department of Electrical, Computer, and Biomedical Engineering, and CNISM, University of Pavia, 27100 Pavia (Italy); Argiolas, N.; Bazzan, M.; Ciampolillo, M. V.; Pozza, G.; Sada, C. [Physics and Astronomy Departement, University of Padova, 35131 Padova (Italy)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Guang-hao; Bai, Yu-hang; Cui, Guo-xin; Li, Chen; Qiu, Xiang-biao; Wu, Di; Lu, Yan-qing, E-mail: yqlu@nju.edu.cn [National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Geng, De-qiang [Jinan Jingzheng Electronics Co., Ltd., Jinan 250100 (China)

    2016-07-15

    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. Photorefractive lithium niobate crystals for applications in photonics

    International Nuclear Information System (INIS)

    Hartwig, U.

    2006-12-01

    Lithium niobate crystals (LiNbO 3 ) generally show a photorefractive response, i.e., light-induced refractive index changes. Crystals are investigated at room temperature and at elevated temperatures. As a result 'classical' photorefractive holographic volume-phase gratings, originating from space charge fields and the electro-optic effect, and 'non-classical' photorefractive volume-phase gratings, which can be traced back to strong absorption gratings, emerge. Single domain and periodically poled crystals (PPLN) are investigated. PPLN is typically used in non-linear optics for frequency conversion. The crystals also show non-linear photorefractive response during holographic recording with isotropically polarized light beams of equal intensity and, in the case of PPLN, by mixing of domain and holographic gratings. The results are important for applications combining the photorefractive and non-linear optical properties of LiNbO 3 . (orig.)

  16. Photoluminescence of Copper-Doped Lithium Niobate Crystals

    Science.gov (United States)

    Gorelik, V. S.; Pyatyshev, A. Yu.; Sidorov, N. V.

    2018-05-01

    The photoluminescence (PL) of copper-doped lithium niobate single crystals is studied using different UV-Vis light-emitting diodes and a pulse-periodic laser with a wavelength of 266 nm as excitation radiation sources. With the resonance excitation from a 527-nm light-emitting diode, the intensity of PL increases sharply (by two orders of magnitude). When using a 467-nm light-emitting diode for excitation, the PL spectrum is characterized by the presence of multiphonon lines in the range of 520-620 nm.

  17. Systematic hardness studies on lithium niobate crystals

    Indian Academy of Sciences (India)

    Unknown

    crystals with different growth origins, and a Fe-doped sample. The problem of load ... The true hardness of LiNbO3 is found to be 630 ± 30 kg/mm2. .... Experimental. Pure lithium ... the index of d strikes at this simple and meaningful defini-.

  18. Twinning structures in near-stoichiometric lithium niobate single crystals

    International Nuclear Information System (INIS)

    Yao, Shuhua; Chen, Yanfeng

    2010-01-01

    A near-stoichiometric lithium niobate single crystal has been grown by the Czochralski method in a hanging double crucible with a continuous powder supply system. Twins were found at one of the three characteristic growth ridges of the as-grown crystal. The twin structure was observed and analyzed by transmission synchrotron topography. The image shifts ΔX and ΔY in the transmission synchrotron topograph were calculated for the 3 anti 2 anti 12 and 0 anti 222 reflections based on results from high-resolution X-ray diffractometry. It is confirmed that one of the {01 anti 1 anti 2} m planes is the composition face of the twin and matrix crystals. The formation mechanism of these twins is discussed. (orig.)

  19. UV laser-assisted fabrication of ridge waveguides in lithium niobate crystals

    OpenAIRE

    Sones, C.L.; Ying, C.Y.J.; Eason, R.W.; Mailis, S.; Ganguly, P.; Soergel, E.

    2010-01-01

    We present a UV laser-assisted method for the fabrication of ridge waveguides in lithium niobate. The UV laser irradiation step provides the refractive index change required for the vertical light confinement in the waveguide and also defines the ferroelectric domain pattern which produces the ridge structures after chemical etching.

  20. Generation of ionizing radiation from lithium niobate crystals

    Science.gov (United States)

    Orlikov, L. N.; Orlikov, N. L.; Arestov, S. I.; Mambetova, K. M.; Shandarov, S. M.

    2017-01-01

    The work done experimentally explores generation of electron and x-ray radiation in the process of heating and cooling monolithic and iron-doped crystals of lithium niobate. Iron doping to the concentrations in the range of 1023 m3 was carried out by adding ferric oxide into the melt during the process of crystal growth. The research into radiation generation was performed at 1-10 Pa. The speed of heating from -10 to 1070 C was 10-20 degrees a minute. Current pulses appeared at 17, 38, 56, 94, 98, 100, 105, 106, 1070 C with the interval of 1-3 minutes. The obtained electron current increased in direct proportion to the crystal surface area. The maximum current was 3mA at the design voltage 11 kV on the crystal with 14,5x10,5x10 mm3 surface area. The article describes the possibility to control the start of generation by introducing priming pulse. The results achieved are explained by the domain repolarization while heating the crystal and the appearance of electric field local strength. Bias and overcharge currents contribute to the appearance of electric strength, which stimulates breakdown and plasma formation. X-ray radiation appears both at the stage of discharge formation and during electron deceleration on gas and target material.

  1. Influence of Fe{sup 3+} substitution on the dielectric and ferroelectric characteristics of Lead Indium Niobate

    Energy Technology Data Exchange (ETDEWEB)

    Divya, A.S.; Kumar, V., E-mail: vkumar10@yahoo.com

    2015-07-15

    Highlights: • Prepared phase-pure Fe{sup 3+}-substituted Lead Indium Niobate, Pb[(In{sub 0.50−x}Fe{sub x})Nb{sub 0.50}]O{sub 3} by sol–gel method. • Spontaneous Relaxor (R) → Ferroelectric (FE) transition observed for the composition with x = 0.20. • Local structural rearrangement responsible for R → FE transition has been confirmed by Raman spectroscopy. - Abstract: Lead Indium Niobate, Pb(In{sub 0.50}Nb{sub 0.50})O{sub 3} (PIN) is a complex perovskite that exhibits Relaxor (R) characteristics. In this study, we report the synthesis of phase-pure compositions in the system Pb[(In{sub 0.50−x}Fe{sub x})Nb{sub 0.50}]O{sub 3} by sol–gel method and discuss the influence of isovalent substitution of Indium by Iron on the dielectric and ferroelectric characteristics. Spontaneous transition to the Ferroelectric (FE) phase has been observed for the composition having x = 0.20. Local structural rearrangements responsible for R → FE transition have also been studied by Raman spectroscopy and are discussed in detail.

  2. Rare-Earth Tantalates and Niobates Single Crystals: Promising Scintillators and Laser Materials

    Directory of Open Access Journals (Sweden)

    Renqin Dou

    2018-01-01

    Full Text Available Rare-earth tantalates, with high density and monoclinic structure, and niobates with monoclinic structure have been paid great attention as potential optical materials. In the last decade, we focused on the crystal growth technology of rare-earth tantalates and niobates and studied their luminescence and physical properties. A series of rare-earth tantalates and niobates crystals have been grown by the Czochralski method successfully. In this work, we summarize the research results on the crystal growth, scintillation, and laser properties of them, including the absorption and emission spectra, spectral parameters, energy levels structure, and so on. Most of the tantalates and niobates exhibit excellent luminescent properties, rich physical properties, and good chemical stability, indicating that they are potential outstanding scintillators and laser materials.

  3. Dielectric and ferroelectric properties of solid solutions based on lead meta niobate

    International Nuclear Information System (INIS)

    Umakantham, K.; Murty, S.N.; Bhanumathi, A.

    1986-01-01

    Pb/sub 2/KNb/sub 5/O/sub 15/ single crystals belong to tungsten bronze structure. Previous work on single crystals of this material has shown that they possess temperature compensated elastic properties and an electromechanical coupling coefficient which is seventeen times as high as quartz and hence are ideally suited for SAW device applications. Experimental work on SAW properties has not been reported so far due to nonavailability of large single crystals. The authors have prepared ceramics of Pb/sub 2/KNb/sub 5/O/sub 15/ modified with lanthanum by conventional sintering. The object of the work is to explore the possibility of using the ceramics for SAW devices. As a first step they have measured the dielectric and ferroelectric properties for different mole fractions of lanthanum

  4. Ferroelectric materials and their applications

    CERN Document Server

    Xu, Y

    2013-01-01

    This book presents the basic physical properties, structure, fabrication methods and applications of ferroelectric materials. These are widely used in various devices, such as piezoelectric/electrostrictive transducers and actuators, pyroelectric infrared detectors, optical integrated circuits, optical data storage, display devices, etc. The ferroelectric materials described in this book include a relatively complete list of practical and promising ferroelectric single crystals, bulk ceramics and thin films. Included are perovskite-type, lithium niobate, tungsten-bronze-type, water-soluable

  5. Ferroelectric and octahedral tilt twin disorder and the lead-free piezoelectric, sodium potassium niobate system

    International Nuclear Information System (INIS)

    Schiemer, Jason; Withers, Ray L.; Liu, Yun; Yi, Zhiguo

    2012-01-01

    Using electron diffraction, trends in the local structural behaviour of the K x Na 1−x NbO 3 (KNN x) ‘solid solution’ system are investigated and interpreted using an order/disorder based theoretical framework. At room temperature, electron diffraction shows a single plane of transverse polarised, diffuse intensity perpendicular to [0 1 0] p ⁎ (p for parent sub-structure) across the entire phase diagram, indicative of ferroelectric disorder along the [0 1 0] p direction co-existing with long range ferroelectric order along the orthogonal [1 0 0] p and [0 0 1] p directions. An additional characteristic pattern of diffuse scattering is also observed, involving rods of diffuse intensity running along the [1 0 0] p * and [0 0 1] p * directions of the perovskite sub-structure and indicative of octahedral tilt disorder about the [1 0 0] p and [0 0 1] p axes co-existing with long range ordered octahedral tilting around the [0 1 0] p direction. A possible crystal chemical explanation for the existence of this latter octahedral tilt disorder is explored through bond valence sum calculations. The possible influence of both types of disorder on the previously refined, room temperature space group/s and average crystal structure/s is examined. - Graphical abstract: [−3,0.−1]p zone axis EDP of K 0.46 Na 0.54 NbO 3 indexed according to both the relevant Pcm21 space groups (no subscripts) and the parent perovskite subcell (denoted by a subscript p). Highlights: ► Characterises ferroelectric and octahedral tilt disorder in the KNN solid solution. ► Discusses the possible driving forces for this disorder. ► Discusses the implications of this disorder for physical properties. ► Discusses the effects of this disorder on powder diffraction data.

  6. Interaction of light with impurities in lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Schwesyg, Judith Renate Marie-Luise

    2011-06-06

    Congruent lithium niobate (LiNbO{sub 3}) and 5-mol% MgO-doped LiNbO{sub 3} (MgO:LN) crystals are widely used as nonlinear-optical crystals in frequency-conversion devices due to their large nonlinear-optic coefficients. These devices usually require high optical pump powers, but absorption of photons by impurities limits their usability due to heat accumulation that leads to thermo-optic refractive index changes. These refractive index changes distort the beam shape and disturb the phase-matching condition. Furthermore pyroelectric fields can build up. In this thesis the residual optical absorption in congruent LiNbO{sub 3} (CLN) and MgO:LN crystals is studied. Absorption spectra of CLN and MgO:LN crystals between 400-2000 nm reveal a residual absorption up to 0.04 cm{sup -1}. This absorption is mainly caused by transition metal impurities. Between 2300-2800 nm unknown hydrogen absorption bands in CLN and MgO:LN are revealed on the order of 0.001 cm{sup -1}. High-temperature annealing is applied to the CLN and MgO:LN crystals, which decreases optical absorption by up to one order of magnitude. As an application, the operation of a 1550-nm pumped singly-resonant CW optical parametric oscillator, resonant around 2600 nm, using a low-loss, periodically-poled, annealed CLN crystal is demonstrated. Another issue that affects CLN is photorefractive damage (PRD), i.e. light-induced refractive index changes. In contrast, MgO:LN crystals do not suffer from PRD even at high optical intensities. However, it is shown in this thesis that PRD can occur within seconds in MgO:LN, using green laser light at light intensity levels as low as 100 mW/cm{sup 2}, if the crystal is heated by several degrees Celsius during or before illumination. Photorefractive damage does not occur in CLN crystals under the same conditions. We show that the pyroelectric effect together with an elevated photoconductivity compared to that of CLN causes this beam distortion and that this effect also

  7. Interaction of light with impurities in lithium niobate crystals

    International Nuclear Information System (INIS)

    Schwesyg, Judith Renate Marie-Luise

    2011-01-01

    Congruent lithium niobate (LiNbO 3 ) and 5-mol% MgO-doped LiNbO 3 (MgO:LN) crystals are widely used as nonlinear-optical crystals in frequency-conversion devices due to their large nonlinear-optic coefficients. These devices usually require high optical pump powers, but absorption of photons by impurities limits their usability due to heat accumulation that leads to thermo-optic refractive index changes. These refractive index changes distort the beam shape and disturb the phase-matching condition. Furthermore pyroelectric fields can build up. In this thesis the residual optical absorption in congruent LiNbO 3 (CLN) and MgO:LN crystals is studied. Absorption spectra of CLN and MgO:LN crystals between 400-2000 nm reveal a residual absorption up to 0.04 cm -1 . This absorption is mainly caused by transition metal impurities. Between 2300-2800 nm unknown hydrogen absorption bands in CLN and MgO:LN are revealed on the order of 0.001 cm -1 . High-temperature annealing is applied to the CLN and MgO:LN crystals, which decreases optical absorption by up to one order of magnitude. As an application, the operation of a 1550-nm pumped singly-resonant CW optical parametric oscillator, resonant around 2600 nm, using a low-loss, periodically-poled, annealed CLN crystal is demonstrated. Another issue that affects CLN is photorefractive damage (PRD), i.e. light-induced refractive index changes. In contrast, MgO:LN crystals do not suffer from PRD even at high optical intensities. However, it is shown in this thesis that PRD can occur within seconds in MgO:LN, using green laser light at light intensity levels as low as 100 mW/cm 2 , if the crystal is heated by several degrees Celsius during or before illumination. Photorefractive damage does not occur in CLN crystals under the same conditions. We show that the pyroelectric effect together with an elevated photoconductivity compared to that of CLN causes this beam distortion and that this effect also influences frequency conversion

  8. Distribution of the solute in the lithium niobate crystal grown by the Stepanov method in a periodically changing external electric field

    International Nuclear Information System (INIS)

    Zhdanov, A.; Nikolayeva, L.; Red'kin, B.

    2000-01-01

    The Iithium niobate crystals with the periodic domain structure are characterised by the capacity for the light frequency adoption of the laser light. Consequently, they are promising for the development of compact light sources. There are several methods of producing periodic ferroelectric domain structures of the lithium niobate crystals in the growth process. It is evident that the main method of production of the periodic structures in the lithium niobate is the Stepanov method. The development of the mathematical model of the variation of the concentration of the alloying solute with the periodic variation of the conditions of growth of the crystal in the growth of the crystal by the Stepanov methods in the conditions of periodic changes of the drawing rate of the crystal V and the temperature of the thermal junction T have been investigated elsewhere. The formation of the domain structure is also possible in the case of the periodic variation of the electric field, during the supply of the alternating voltage between the shaper and the seed. In this work, we proposed mathematical model discounting the process of formation of the domain structure in the alternating electric field during the growth of the lithium niobate crystal by the Stepanov method. In the mathematical modelling we obtain the numerical solutions of the unidimensional nonstationary problem of the Stepanov type, the diffusion equation for concentration, and the Laplace capillary equation. The proposed mathematical model is at the present and the most complete and accurate description of the variation of the concentration of the solute in the growing crystal. The semi-discrete Galerkin method was used for the equations

  9. Domain wall kinetics of lithium niobate single crystals near the hexagonal corner

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Ju Won [Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Ko, Do-Kyeong [Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Advanced Photonics Research Institute, GIST, 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Yu, Nan Ei, E-mail: neyu@gist.ac.kr, E-mail: jhro@pnu.edu [Advanced Photonics Research Institute, GIST, 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Kitamura, Kenji [National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Ro, Jung Hoon, E-mail: neyu@gist.ac.kr, E-mail: jhro@pnu.edu [Department of Biomedical Engineering, School of Medicine, Pusan National University, Busan 602-739 (Korea, Republic of)

    2015-03-09

    A mesospheric approach based on a simple microscopic 2D Ising model in a hexagonal lattice plane is proposed to explain macroscopic “asymmetric in-out domain wall motion” observation in the (0001) plane of MgO-doped stoichiometric lithium niobate. Under application of an electric field that was higher than the conventional coercive field (E{sub c}) to the ferroelectric crystal, a natural hexagonal domain was obtained with walls that were parallel to the Y-axis of the crystal. When a fraction of the coercive field of around 0.1E{sub c} is applied in the reverse direction, this hexagonal domain is shrunk (moved inward) from the corner site into a shape with a corner angle of around 150° and 15° wall slopes to the Y-axis. A flipped electric field of 0.15E{sub c} is then applied to recover the natural hexagonal shape, and the 150° corner shape changes into a flat wall with 30° slope (moved outward). The differences in corner domain shapes between inward and outward domain motion were analyzed theoretically in terms of corner and wall site energies, which are described using the domain corner angle and wall slope with respect to the crystal Y-axis, respectively. In the inward domain wall motion case, the energy levels of the evolving 150° domain corner and 15° slope walls are most competitive, and could co-exist. In the outward case, the energy levels of corners with angles >180° are highly stable when compared with the possible domain walls; only a flat wall with 30° slope to the Y-axis is possible during outward motion.

  10. Thermo-electric oxidization of iron in lithium niobate crystals

    International Nuclear Information System (INIS)

    Falk, Matthias

    2007-01-01

    Lithium niobate crystals (LiNbO 3 ) are a promising material for nonlinear-optical applications like frequency conversion to generate visible light, e.g., in laser displays, but their achievable output power is greatly limited by the ''optical damage'', i.e., light-induced refractive-index changes caused by excitation of electrons from iron impurities and the subsequent retrapping in unilluminated areas of the crystal. The resulting space-charge fields modify the refractive indices due to the electro-optic effect. By this ''photorefractive effect'' the phase-matching condition, i.e., the avoidance of destructive interference between light generated at different crystal positions due to the dispersion of the fundamental wave and the converted wave, is disturbed critically above a certain light intensity threshold. The influence of annealing treatments conducted in the presence of an externally applied electric field (''thermo-electric oxidization'') on the valence state of iron impurities and thereby on the optical damage is investigated. It is observed that for highly iron-doped LiNbO 3 crystals this treatment leads to a nearly complete oxidization from Fe 2+ to Fe 3+ indicated by the disappearance of the absorption caused by Fe 2+ . During the treatment an absorption front forms that moves through the crystal. The absorption in the visible as well as the electrical conductivity are decreased by up to five orders of magnitude due to this novel treatment. The ratio of the Fe 2+ concentration to the total iron concentration - a measure for the strength of the oxidization - is in the order of 10 -6 for oxidized crystals whereas it is about 10 -1 for untreated samples. Birefringence changes are observed at the absorption front that are explained by the removal of hydrogen and lithium ions from the crystal that compensate for the charges of the also removed electrons from Fe 2+ . A microscopic shock-wave model is developed that explains the observed absorption front by

  11. Tip-induced domain growth on the non-polar cuts of lithium niobate single-crystals

    Science.gov (United States)

    Alikin, D. O.; Ievlev, A. V.; Turygin, A. P.; Lobov, A. I.; Kalinin, S. V.; Shur, V. Ya.

    2015-05-01

    Currently, ferroelectric materials with designed domain structures are considered as a perspective material for new generation of photonic, data storage, and data processing devices. Application of external electric field is the most convenient way of the domain structure formation. Lots of papers are devoted to the investigation of domain kinetics on polar surface of crystals while the forward growth remains one of the most mysterious stages due to lack of experimental methods allowing to study it. Here, we performed tip-induced polarization reversal on X- and Y-non-polar cuts in single-crystal of congruent lithium niobate which allows us to study the forward growth with high spatial resolution. The revealed difference in the shape and length of domains induced on X- and Y-cuts is beyond previously developed theoretical approaches used for the theoretical consideration of the domains growth at non-polar ferroelectric surfaces. To explain experimental results, we used kinetic approach with anisotropy of screening efficiency along different crystallographic directions.

  12. Gamma radiation effects on photorefractive and photoelectric properties of lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vartanyan, Eh.S.; Ovsepyan, R.K.; Pogosyan, A.R.; Timofeev, A.L.

    1984-08-01

    Investigations into the gamma radiation effect on the photorefractive aned photoelectric properties of lithium niobate crystals have been carried out for the first time. Gamma irradiation has been found to lead to an increase in the photorefractive sensitivity. The effect of optical decoloration has been discovered for the first time along with photorelaxation currents resulting from radiation center decay under the action of light. It has been shown that an increase of photorefractive sensitivity in gamma-irradiated lithium niobate crystals is caused by a new photorefraction mechanism - photorelaxation currents.

  13. Efficient femtosecond mid-infrared pulse generation by dispersivewave radiation in bulk lithium niobate crystal

    DEFF Research Database (Denmark)

    Zhou, Binbin; Guo, Hairun; Bache, Morten

    2014-01-01

    We experimentally demonstrate efficient mid-infrared pulse generation by dispersive wave radiation in bulk lithium niobate crystal. Femtosecond mid-IR pulses centering from 2.8–2.92 µm are generated using the single pump wavelengths from 1.25–1.45 µm.......We experimentally demonstrate efficient mid-infrared pulse generation by dispersive wave radiation in bulk lithium niobate crystal. Femtosecond mid-IR pulses centering from 2.8–2.92 µm are generated using the single pump wavelengths from 1.25–1.45 µm....

  14. Alignment structures in ferroelectric liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Islam, N.U

    1998-07-01

    Although for many years liquid crystals were of purely scientific interest, they have now become ubiquitous in everyday life. The use of the nematic liquid crystal phase in flat panel display applications has been the main factor in this popularity. However, with the advent of the SuperTwist Nematic (STN) device, the limits to which this phase could be exploited for display applications was perhaps reached. With the discovery by Clark et al. of the Surface Stabilised Ferroelectric Liquid Crystal (SSFLC) configuration, the possibility arose of using chiral smectic liquid crystals to create large area, passively addressed, fast switching, flat panel displays. Unfortunately, the structures that form within smectic liquid crystals, and the dynamics of the switching within these, are still not fully understood. In this thesis we address the former of these, making a detailed the study of the structures that form within tilted smectic liquid crystal devices. We present here the first complete theoretical and experimental study of various different ferroelectric liquid crystal materials, where we employed theoretical models based on a simple set of assumptions to understand the behaviour of a set of increasingly complex experimental systems. We started with the simplest of these, Freely Suspended Smectic Films (FSSFs) and then worked with progressively more realistic systems in the form of homeotropically, and later, homogeneously aligned liquid crystal cells. The equilibrium structures that form get particularly complex in the last case, taking the form of tilted and chevron layering structures. In each of these cases, the predictions of the modelling are compared with our experimental results. Further, we present here the first model of the chevron cusp that seeks to include the effects of biaxiality in the S{sub C} phase. We also present a model that seeks to analyse the stability of the chevron layering structure and its relationship with tilted layers. This includes

  15. Alignment structures in ferroelectric liquid crystals

    International Nuclear Information System (INIS)

    Islam, N.U.

    1998-01-01

    Although for many years liquid crystals were of purely scientific interest, they have now become ubiquitous in everyday life. The use of the nematic liquid crystal phase in flat panel display applications has been the main factor in this popularity. However, with the advent of the SuperTwist Nematic (STN) device, the limits to which this phase could be exploited for display applications was perhaps reached. With the discovery by Clark et al. of the Surface Stabilised Ferroelectric Liquid Crystal (SSFLC) configuration, the possibility arose of using chiral smectic liquid crystals to create large area, passively addressed, fast switching, flat panel displays. Unfortunately, the structures that form within smectic liquid crystals, and the dynamics of the switching within these, are still not fully understood. In this thesis we address the former of these, making a detailed the study of the structures that form within tilted smectic liquid crystal devices. We present here the first complete theoretical and experimental study of various different ferroelectric liquid crystal materials, where we employed theoretical models based on a simple set of assumptions to understand the behaviour of a set of increasingly complex experimental systems. We started with the simplest of these, Freely Suspended Smectic Films (FSSFs) and then worked with progressively more realistic systems in the form of homeotropically, and later, homogeneously aligned liquid crystal cells. The equilibrium structures that form get particularly complex in the last case, taking the form of tilted and chevron layering structures. In each of these cases, the predictions of the modelling are compared with our experimental results. Further, we present here the first model of the chevron cusp that seeks to include the effects of biaxiality in the S C phase. We also present a model that seeks to analyse the stability of the chevron layering structure and its relationship with tilted layers. This includes an

  16. Crystallization of Reduced Strontium and Barium Niobate Perovskites from Borate Fluxes.

    NARCIS (Netherlands)

    Hessen, B.; Sunshine, S.A.; Siegrist, T.; Jimenez, R.

    1991-01-01

    Single crystals of three AxNbO3 (A = Sr, Ba) reduced niobate cubic perovskites have been obtained by recrystallization of reduced ternary ceramic precursors from borate fluxes under high-vacuum. Product formation could be influenced by variation of the alkaline-earth metal oxide content of the flux,

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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. (orig.)

  18. Visualization of ferroelectric domain structures in lithium niobate by means of confocal nonlinear microscopy; Visualisierung ferroelektrischer Domaenenstrukturen in Lithiumniobat mittels konfokaler nichtlinearer Mikroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Berth, Gerhard

    2010-07-01

    In the field of integrated optics nonlinear-optical effects play a central role. A typical example for the commercial use of such phenomena is the frequency conversion. A deciding parameter is here the phase matching, which determines the quantity of the constructive interaction range of contributing optical fields. In view of a high efficiency of such processes the dispersion of a crystal must be balanced for the contributing frequencies. In nonlinear components on the base of optical waveguides the principle of the ''quasi-phase matching'' is applied, which uses the microdomain inversion. Phase jumps occuring at the domain boundaries compensate in the mean the different phase velocities. The application range of such periodical structures depends essentially on sharpness, homogeneity, depth extent, and period of the domain structure. The nonlinear confocal laser scanning microscopy makes a mapping of this transferred ferroelectric domain structure possible. Primary aim of this thesis is the characterization and mapping of the transferred ferroelectric domain structure in lithium niobate. A modularly kept confocal microscope makes here a nonlinear analysis in reflection and transmission geometry possible. In both geometries systematic studies as function of important process parameters were performed. It was shown that because of the larger nonlinear coherence length in the transmission modus the SHG ensues above all in forward direction. By depth-resolved studies at Z-cut PPLN structured between the surface region and the volume crystal a flippling of the SHG contrast could be observed. In samples with circular pole structure additionally in the crystal a transition to a hexagonal structure took place. In the Ti:PPLN strip waveguide a strong and specific increasement of the nonlinear signal of the domain walls was discovered. Here also the usual SHG surface contrast between dhe domains and the boundaries is inverted. Also differently processed

  19. Near-field-optical-microscopy studies of micro-modifications caused by femtosecond laser irradiation in lithium niobate crystals

    International Nuclear Information System (INIS)

    Lamela, J.; Jaque, D.; Rodenas, A.; Jaque, F.; Torchia, G.A.; Vazquez, J.R.; Mendez, C.; Roso, L.

    2008-01-01

    Near-field-optical-microscopy has been used to study the micro-modifications caused by femtosecond laser pulses focused at the surface and in the volume of lithium niobate crystals. We have found experimental evidence of the existence, close to femtosecond ablation craters, of periodic modifications in the surface reflectivity. In addition, the potential application of near-field-optical microscopy for the spatial location of permanent modifications caused by femtosecond pulses focused inside lithium niobate crystals has been also demonstrated. (orig.)

  20. Propagation of light in the lithium niobate crystal along directions close to an optical axis

    International Nuclear Information System (INIS)

    Volkov, V.V.; Egorova, G.A.; Lonskij, Eh.S.; Potapov, E.V.; Rakov, A.V.

    1978-01-01

    Theoretical and experimental results are given of studying some characteristics of electrooptical modulator from lithium niobate when propagating in it linear-polarized light in directions close to the optical axis, the electric field being applied along the X axis. It has been shown that an increase in an angle of deviation from the optical axis of a light beam passing in the crystal changes the value of the controlling voltage. This is accompanied by the rotation of the polarization plane and the change in the intensity of the light being passed. The methods have been proposed of increasing the modulator aperture, determining the main refraction indices and some electrooptical coefficients fo the lithium niobate crystal

  1. Conversion of broadband thermal radiation in lithium niobate crystals of various compositions

    Science.gov (United States)

    Syuy, A. V.; Litvinova, M. N.; Goncharova, P. S.; Sidorov, N. V.; Palatnikov, M. N.; Krishtop, V. V.; Likhtin, V. V.

    2013-05-01

    The conversion of the broadband thermal radiation in stoichiometric ( R = 1) lithium niobate single crystals that are grown from melt with 58.6 mol % of LiO2, congruent ( R = Li/Nb = 0.946) melt with the K2O flux admixture (4.5 and 6.0 wt %), and congruent melt and in congruent single crystals doped with the Zn2+, Gd3+, and Er3+ cations is studied. It is demonstrated that the conversion efficiency of the stoichiometric crystal that is grown from the melt with 58.6 mol % of LiO2 is less than the conversion efficiency of congruent crystal. In addition, the stoichiometric and almost stoichiometric crystals and the doped congruent crystals exhibit the blue shift of the peak conversion intensity in comparison with a nominally pure congruent crystal. For the congruent crystals, the conversion intensities peak at 520 and 495 nm, respectively.

  2. Continuous wave ultraviolet radiation induced frustration of etching in lithium niobate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mailis, S.; Riziotis, C.; Smith, P.G.R.; Scott, J.G.; Eason, R.W

    2003-02-15

    Illumination of the -z face of congruent lithium niobate single crystals with continuous wave (c.w.) ultraviolet (UV) laser radiation modifies the response of the surface to subsequent acid etching. A frequency doubled Ar{sup +} laser ({lambda}=244 nm) was used to illuminate the -z crystal face making it resistive to HF etching and thus transforming the illuminated tracks into ridge structures. This process enables the fabrication of relief patterns in a photolithographic manner. Spatially resolved Raman spectroscopy indicates preservation of the good crystal quality after irradiation.

  3. All-optical switching based on a tunable Fano-like resonance in nonlinear ferroelectric photonic crystals

    International Nuclear Information System (INIS)

    Chai, Zhen; Hu, Xiaoyong; Gong, Qihuang

    2013-01-01

    A low-power all-optical switching is presented based on the all-optical tunable Fano-like resonance in a two-dimensional nonlinear ferroelectric photonic crystal made of polycrystalline lithium niobate. An asymmetric Fano-like line shape is achieved in the transmission spectrum by using two cascaded and uncoupled photonic crystal microcavities. The physical mechanism underlying the all-optical switching is attributed to the dynamic shift of the Fano-like resonance peak caused by variations in the dispersion relations of the photonic crystal structure induced by pump light. A large switching efficiency of 61% is reached under excitation of a weak pump light with an intensity as low as 1 MW cm −2 . (paper)

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

    Energy Technology Data Exchange (ETDEWEB)

    Neumayer, Sabine M.; Rodriguez, Brian J., E-mail: brian.rodriguez@ucd.ie [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4 (Ireland); Strelcov, Evgheni; Kravchenko, Ivan I.; Kalinin, Sergei V. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Manzo, Michele; Gallo, Katia [Department of Applied Physics, KTH - Royal Institute of Technology, Roslagstullbacken 21, 10691 Stockholm (Sweden); Kholkin, Andrei L. [Department of Physics and CICECO-Aveiro Institute of Materials, 3810-193 Aveiro, Portugal and Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation)

    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. In addition, local introduction of proton exchanged phases allows for inhibition of domain nucleation or destabilization, which can be utilized to modify domain patterns. Polarization dependent current flow, attributed to charged domain walls and band bending, demonstrates the rectifying ability of Mg:LN in combination with suitable metal electrodes that allow for further tailoring of conductivity.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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. In addition, local introduction of proton exchanged phases allows for inhibition of domain nucleation or destabilization, which can be utilized to modify domain patterns. Polarization dependent current flow, attributed to charged domain walls and band bending, demonstrates the rectifying ability of Mg:LN in combination with suitable metal electrodes that allow for further tailoring of conductivity

  6. Photorefractive lithium niobate crystals for applications in photonics; Photorefraktive Lithiumniobatkristalle fuer Anwendungen in der Photonik

    Energy Technology Data Exchange (ETDEWEB)

    Hartwig, U.

    2006-12-15

    Lithium niobate crystals (LiNbO{sub 3}) generally show a photorefractive response, i.e., light-induced refractive index changes. Crystals are investigated at room temperature and at elevated temperatures. As a result 'classical' photorefractive holographic volume-phase gratings, originating from space charge fields and the electro-optic effect, and 'non-classical' photorefractive volume-phase gratings, which can be traced back to strong absorption gratings, emerge. Single domain and periodically poled crystals (PPLN) are investigated. PPLN is typically used in non-linear optics for frequency conversion. The crystals also show non-linear photorefractive response during holographic recording with isotropically polarized light beams of equal intensity and, in the case of PPLN, by mixing of domain and holographic gratings. The results are important for applications combining the photorefractive and non-linear optical properties of LiNbO{sub 3}. (orig.)

  7. Ab-initio and atomistic study of the ferroelectric properties of Cu doped potassium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Koerbel, Sabine; Elsaesser, Christian [Fraunhofer-Institut fuer Werkstoffmechanik IWM, Woehlerstrasse 11, 79108 Freiburg (Germany)

    2011-07-01

    KNbO{sub 3} is one end member of the solid solution (K,Na)NbO{sub 3} (KNN), which has promising ferroelectric properties to become a future lead-free substitute for lead zirconate titanate Pb(Zr,Ti)O{sub 3} (PZT) in piezoelectric actors and sensors. Both KNN and PZT exhibit a phase transition with composition and a morphotropic phase boundary, at which enhanced piezoelectric coefficients are obtained. The material properties of PZT and KNN are commonly optimized by doping. E.g., CuO can be added when fabricating KNN as a sintering aid. Ab initio density functional theory and atomistic simulation using a classical shell model potential have been combined to investigate low Cu concentrations in the KNbO{sub 3}-CuNbO{sub 3} system. The atomistic model predicts a morphotropic phase boundary at a few percent Cu, analogous to the one found in the LiNbO{sub 3}-KNbO{sub 3} system.

  8. Effect of domains configuration on crystal structure in ferroelectric ...

    Indian Academy of Sciences (India)

    2017-09-09

    Sep 9, 2017 ... It is well known that domains and crystal structure control the physical properties of ferroelectrics. ... The as-prepared ceramics were crushed to fine pow- ders. ..... [1] Gao J, Xue D, Wang Y, Wang D, Zhang L, Wu H et al 2011.

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

    Energy Technology Data Exchange (ETDEWEB)

    Trull, J.; Wang, B.; Parra, A.; Vilaseca, R.; Cojocaru, C. [Departament de Física i Enginyeria Nuclear, Universitat Politècnica Catalunya, Terrassa 08222 (Spain); Sola, I. [Grupo de Investigación en Óptica Extrema (GIOE), Departamento de Física Aplicada, Universidad de Salamanca, Plaza de la Merced s/n, 37008 Salamanca (Spain); Krolikowski, W. [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Science Program, Texas A and M University at Qatar, Doha (Qatar); Sheng, Y. [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

    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.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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

  11. Domain-Reversed Lithium Niobate Single-Crystal Fibers are Potentially for Efficient Terahertz Wave Generation

    Directory of Open Access Journals (Sweden)

    Yalin Lu

    2008-01-01

    Full Text Available Nonlinear frequency conversion remains one of the dominant approaches to efficiently generate THz waves. Significant material absorption in the THz range is the main factor impeding the progress towards this direction. In this research, a new multicladding nonlinear fiber design was proposed to solve this problem, and as the major experimental effort, periodic domain structure was introduced into lithium niobate single-crystal fibers by electrical poling. The introduced periodic domain structures were nondestructively revealed using a crossly polarized optical microscope and a confocal scanning optical microscope for quality assurance.

  12. Lithium niobate bulk crystallization promoted by CO2 laser radiation

    Science.gov (United States)

    Ferreira, N. M.; Costa, F. M.; Nogueira, R. N.; Graça, M. P. F.

    2012-09-01

    The crystallization induced by laser radiation is a very promising technique to promote glass/ceramic transformation, being already used to produce crystalline patterns on glass surfaces. In this work, a SiO2-Li2O-Nb2O5 glass, prepared by the sol-gel route, was submitted to CO2 laser radiation and conventional heat-treatments in order to induce the LiNbO3 crystallization. The structure and morphology of the samples prepared by both routes was analyzed as a function of exposure time, radiation power and heat-treatment temperatures by XRD, Raman spectroscopy and SEM. The results reveal a correlation between the crystallization degree of LiNbO3 particles and glass matrix with the heat treatment type and experimental parameters. An heat-treatment at 650 °C/4 h was necessary to induce crystallization in heat treatments samples while 4 W/500 s was enough for laser radiation ones, corresponding a reduction time processing of ˜14 000 s.

  13. Acoustic emission mechanism at switching of ferroelectric crystals

    International Nuclear Information System (INIS)

    Belov, V.V.; Morozova, G.P.; Serdobol'skaya, O.Yu.

    1986-01-01

    Process of acoustic emission (AE) in lead germanate (PGO) representing pure ferroelectric, and gadolinium molybdate (GMO) representing ferroelectric-ferroelastic, for which switching may be conducted both by the field and pressure, were studied. A conclusion has been drawn that piezoelectric excitation of a crystal from the surface by pulses of overpolarization current in the process of domain coalescence is the main AE source in PGO. Not only piezoresponse, but also direct sound generation in the moment of domain penetration and collapse is considered as AE mechanism in GMO

  14. Acoustic emission mechanism at switching of ferroelectric crystals

    Energy Technology Data Exchange (ETDEWEB)

    Belov, V V; Morozova, G P; Serdobol' skaya, O Yu

    1986-01-01

    Process of acoustic emission (AE) in lead germanate (PGO) representing pure ferroelectric, and gadolinium molybdate (GMO) representing ferroelectric-ferroelastic, for which switching may be conducted both by the field and pressure, were studied. A conclusion has been drawn that piezoelectric excitation of a crystal from the surface by pulses of overpolarization current in the process of domain coalescence is the main AE source in PGO. Not only piezoresponse, but also direct sound generation in the moment of domain penetration and collapse is considered as AE mechanism in GMO.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Dahuai; Yao, Jiaying [School of Physics, Nankai University, Tianjin 300071 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Kong, Yongfa, E-mail: kongyf@nankai.edu.cn [School of Physics, Nankai University, Tianjin 300071 (China); MOE Key Laboratory of Weak-Light Nonlinear Photonics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China); R and D Center, Taishan Sports Industry Group, Leling 253600 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Liu, Shiguo [School of Physics, Nankai University, Tianjin 300071 (China); Zhang, Ling; Chen, Shaolin [MOE Key Laboratory of Weak-Light Nonlinear Photonics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China); Xu, Jingjun [School of Physics, Nankai University, Tianjin 300071 (China); MOE Key Laboratory of Weak-Light Nonlinear Photonics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China)

    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.

  17. Piezo-optic surfaces of lithium niobate crystals

    International Nuclear Information System (INIS)

    Mytsyk, B. G.; Dem'yanyshyn, N. M.

    2006-01-01

    A method of construction of the spatial distribution of the piezo-optic effect in crystals is proposed. A particular case of this method is the known technique of construction of indicator surfaces of the piezo-optic effect. The essence of the proposed method consists in determining the difference in the radius vectors of the optical indicatrix perturbed by stress and the free optical indicatrix. It is shown that this difference in the radius vectors is mathematically identical to the law of transformation of the piezo-optic tensor during the rotation of the coordinate system

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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. (paper)

  19. Crystal structure and phase transitions of sodium potassium niobate perovskites

    Science.gov (United States)

    Tellier, J.; Malic, B.; Dkhil, B.; Jenko, D.; Cilensek, J.; Kosec, M.

    2009-02-01

    This paper presents the crystal structure and the phase transitions of K xNa 1- xNbO 3 (0.4 ≤ x ≤ 0.6). X-ray diffraction measurements were used to follow the change of the unit-cell parameters and the symmetry in the temperature range 100-800 K. At room temperature all the compositions exhibited a monoclinic metric of the unit cell with a small monoclinic distortion (90.32° ≤ β ≤ 90.34°). No major change of symmetry was evidenced in the investigated compositional range, which should be characteristic of the morphotropic phase-boundary region. With increasing temperature, the samples underwent first-order monoclinic-tetragonal and tetragonal-cubic transitions. Only the potassium-rich phases were rhombohedral at 100 K.

  20. Material modifications in lithium niobate and lithium tantalate crystals by ion irradiation

    International Nuclear Information System (INIS)

    Raeth, Niels Lennart

    2017-01-01

    The artificially produced crystals lithium niobate (LiNbO 3 ) and the closely related lithium tantalate (LiTaO 3 ) are proven starting materials for producing active and passive devices that can guide, amplify, switch and process light. For this purpose, it is often necessary to be able to influence the refractive index of the substrate targeted, which is possible in addition to other methods by irradiation of the materials with fast light ions. In this work, lithium niobate and lithium tantalate crystals are irradiated with alpha particles, 3 He ions, deuterons, and protons at projectile energies of up to 14 MeV / nucleon. Energy and crystal thickness are chosen so that the projectiles penetrate the entire sample and are not implanted. All isotopes responsible for the unwanted nuclear activation of the crystals due to the irradiation are relatively short-lived and overall the activation decreases fast enough to allow the safe handling of the irradiated samples after a storage period of a few days to a few weeks. The refractive index changes produced in lithium niobate and lithium tantalate by irradiation with the different projectiles are determined interferometrically and can also be measured by suitable choice of the sample geometry as a function of the ion penetration depth: In LiNbO 3 the ordinary refractive index decreases, the extraordinary increases equally. In LiTaO 3 , both the ordinary and the extraordinary refractive indices decrease as a result of the irradiation; the ordinary refractive index change is many times stronger than the extraordinary one. There is an enormous long-term stability at room temperature for both crystal systems: Even after eleven (LiNbO 3 ) or three (LiTaO 3 ) years, no decrease in the ion beam-induced refractive index change can be observed. The ion beam-induced refractive index changes are probably the result of atomic displacements such as vacancies, defect clusters or ''latent tracks''. An explanation for

  1. X-ray absorption spectroscopy investigation of structurally modified lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vitova, Tonya

    2008-02-15

    The type and concentration of impurity centers in different valence states are crucial for tuning the photorefractive properties of doped Lithium Niobate (LN) crystals. X-ray Absorption Spectroscopy (XAS) is an appropriate tool for studying the local structure of impurity centers. XAS combined with absorption in UV/VIS/IR and High Resolution X-ray Emission Spectroscopy (HRXES) provide information about the valence state of the dopant ions in as-grown, reduced or oxidized doped LN crystals. Cu (Cu{sup 1+} and Cu{sup 2+}) and Fe (Fe{sup 2+} and Fe{sup 3+}) atoms are found in two different valence states, whereas there are indications for a third Mn valency, in addition to Mn{sup 2+} and Mn{sup 3+} in manganese-doped LN crystals. One of the charge compensation mechanisms during reduction of copper- doped LN crystals is outgassing of oxygen atoms. Cu ions in the reduced crystals have at least two different site symmetries: twofold (Cu{sup 1+}) and sixfold (Cu{sup 2+}) coordinated by O atoms. Fe and Mn atoms are coordinated by six O atoms. Cu and Fe ions are found to occupy only Li sites, whereas Mn ions are also incorporated into Li and Nb sites. The refractive index change in LN crystals irradiated with {sup 3}He{sup 2+} ions is caused by structurally disordered centers, where Nb atoms are displaced from normal crystallographic sites and Li or/and O vacancies are present. (orig.)

  2. X-ray absorption spectroscopy investigation of structurally modified lithium niobate crystals

    International Nuclear Information System (INIS)

    Vitova, Tonya

    2008-02-01

    The type and concentration of impurity centers in different valence states are crucial for tuning the photorefractive properties of doped Lithium Niobate (LN) crystals. X-ray Absorption Spectroscopy (XAS) is an appropriate tool for studying the local structure of impurity centers. XAS combined with absorption in UV/VIS/IR and High Resolution X-ray Emission Spectroscopy (HRXES) provide information about the valence state of the dopant ions in as-grown, reduced or oxidized doped LN crystals. Cu (Cu 1+ and Cu 2+ ) and Fe (Fe 2+ and Fe 3+ ) atoms are found in two different valence states, whereas there are indications for a third Mn valency, in addition to Mn 2+ and Mn 3+ in manganese-doped LN crystals. One of the charge compensation mechanisms during reduction of copper- doped LN crystals is outgassing of oxygen atoms. Cu ions in the reduced crystals have at least two different site symmetries: twofold (Cu 1+ ) and sixfold (Cu 2+ ) coordinated by O atoms. Fe and Mn atoms are coordinated by six O atoms. Cu and Fe ions are found to occupy only Li sites, whereas Mn ions are also incorporated into Li and Nb sites. The refractive index change in LN crystals irradiated with 3 He 2+ ions is caused by structurally disordered centers, where Nb atoms are displaced from normal crystallographic sites and Li or/and O vacancies are present. (orig.)

  3. Nanostructured sodium lithium niobate and lithium niobium tantalate solid solutions obtained by controlled crystallization of glass

    International Nuclear Information System (INIS)

    Radonjic, L.; Todorovic, M.; Miladinovic, J.

    2005-01-01

    Transparent, nanostructured glass ceramics based on ferroelectric solid solutions of the type Na 1-x Li x NbO 3 (in very narrow composition regions for x = 0.12 and 0.93) and LiNb 1-y Ta y O 3 (y = 0.5 unlimited solid solubility), can be obtained by controlled crystallization of glass. The parent glass samples were prepared by conventional melt-quenching technique. Heat-treatment of the parent glasses was performed at the various temperatures, for the same time. The glass structure evolution during the controlled crystallization was examined by FT-IR spectroscopy analysis. Crystalline phases were identified by X-ray diffraction analysis and SEM was used for microstructure characterization. Densities of the crystallized glasses were measured by Archimedean principle. The capacitance and dielectric loss tangent were measured at a frequency of 1 kHz, at the room temperature. It was found that in the all investigated systems crystallize solid solutions Na 1-x Li x NbO 3 and LiNb 1-y Ta y O 3 in the glassy matrix, have crystal size on nanoscale (less than 100 nm), which is one of requirements to get a transparent glass ceramic that could be a good ferroelectric material regarding to the measured properties

  4. Losses in Ferroelectric Materials

    Science.gov (United States)

    Liu, Gang; Zhang, Shujun; Jiang, Wenhua; Cao, Wenwu

    2015-01-01

    Ferroelectric materials are the best dielectric and piezoelectric materials known today. Since the discovery of barium titanate in the 1940s, lead zirconate titanate ceramics in the 1950s and relaxor-PT single crystals (such as lead magnesium niobate-lead titanate and lead zinc niobate-lead titanate) in the 1980s and 1990s, perovskite ferroelectric materials have been the dominating piezoelectric materials for electromechanical devices, and are widely used in sensors, actuators and ultrasonic transducers. Energy losses (or energy dissipation) in ferroelectrics are one of the most critical issues for high power devices, such as therapeutic ultrasonic transducers, large displacement actuators, SONAR projectors, and high frequency medical imaging transducers. The losses of ferroelectric materials have three distinct types, i.e., elastic, piezoelectric and dielectric losses. People have been investigating the mechanisms of these losses and are trying hard to control and minimize them so as to reduce performance degradation in electromechanical devices. There are impressive progresses made in the past several decades on this topic, but some confusions still exist. Therefore, a systematic review to define related concepts and clear up confusions is urgently in need. With this objective in mind, we provide here a comprehensive review on the energy losses in ferroelectrics, including related mechanisms, characterization techniques and collections of published data on many ferroelectric materials to provide a useful resource for interested scientists and engineers to design electromechanical devices and to gain a global perspective on the complex physical phenomena involved. More importantly, based on the analysis of available information, we proposed a general theoretical model to describe the inherent relationships among elastic, dielectric, piezoelectric and mechanical losses. For multi-domain ferroelectric single crystals and ceramics, intrinsic and extrinsic energy

  5. Losses in Ferroelectric Materials.

    Science.gov (United States)

    Liu, Gang; Zhang, Shujun; Jiang, Wenhua; Cao, Wenwu

    2015-03-01

    Ferroelectric materials are the best dielectric and piezoelectric materials known today. Since the discovery of barium titanate in the 1940s, lead zirconate titanate ceramics in the 1950s and relaxor-PT single crystals (such as lead magnesium niobate-lead titanate and lead zinc niobate-lead titanate) in the 1980s and 1990s, perovskite ferroelectric materials have been the dominating piezoelectric materials for electromechanical devices, and are widely used in sensors, actuators and ultrasonic transducers. Energy losses (or energy dissipation) in ferroelectrics are one of the most critical issues for high power devices, such as therapeutic ultrasonic transducers, large displacement actuators, SONAR projectors, and high frequency medical imaging transducers. The losses of ferroelectric materials have three distinct types, i.e., elastic, piezoelectric and dielectric losses. People have been investigating the mechanisms of these losses and are trying hard to control and minimize them so as to reduce performance degradation in electromechanical devices. There are impressive progresses made in the past several decades on this topic, but some confusions still exist. Therefore, a systematic review to define related concepts and clear up confusions is urgently in need. With this objective in mind, we provide here a comprehensive review on the energy losses in ferroelectrics, including related mechanisms, characterization techniques and collections of published data on many ferroelectric materials to provide a useful resource for interested scientists and engineers to design electromechanical devices and to gain a global perspective on the complex physical phenomena involved. More importantly, based on the analysis of available information, we proposed a general theoretical model to describe the inherent relationships among elastic, dielectric, piezoelectric and mechanical losses. For multi-domain ferroelectric single crystals and ceramics, intrinsic and extrinsic energy

  6. Conical light scattering in strontium barium niobate crystals related to an intrinsic composition inhomogeneity

    International Nuclear Information System (INIS)

    Bastwoeste, K; Sander, U; Imlau, M

    2007-01-01

    Conical light scattering is uncovered in poly- and mono-domain, nominally pure and Eu-doped strontium barium niobate (SBN) crystals over a wide temperature regime. The appearance of two scattering cones, a scattering line and a corona is observed and can be explained comprehensively within the Ewald sphere concept. Photorefraction, scattering from domain boundaries or from growth striations can be excluded from explaining the origin of the scattering. It is shown that the temperature-persistent scattering process is related to a growth-induced seeding rod, i.e. a composition inhomogeneity primarily localized at the centre of the SBN sample. The rod is directed parallel to the c axis and yields a refractive-index inhomogeneity with spatial frequencies on the micro-scale

  7. Remarkable Strontium B-Site Occupancy in FerroelectricPb(Zr1-xTix)O3 Solid Solutions Doped with Cryolite-Type StrontiumNiobate

    Energy Technology Data Exchange (ETDEWEB)

    Feltz, A.; Schmidt-Winkel, P.; Schossman, M.; Booth, C.H.; Albering, J.

    2007-04-26

    New high-performance ferroelectric materials based on Pb(Zr{sub 1-x}Ti{sub x})O{sub 3} (PZT) that are doped with cryolite-type strontium niobate (SNO, Sr{sub 4}(Sr{sub 2-2y/3}Nb{sub 2+2y/3})O{sub 11+y}V{sub 0,1-y} with 0 {le} y {le} 1), hence denoted PZT:SNO, and their microscopic structure are described. The combination of exceptional piezoelectric properties, i.e. a piezoelectric strain constant of d{sub 33} {approx} 760 pm/V, with excellent stability and degradation resistance makes ferroelectric PZT:SNO solid solutions very attractive for use in novel and innovative piezoelectric actuator and transducer applications. Extended X-ray absorption fine-structure (EXAFS) analyses of PZT:SNO samples revealed that {approx}10 % of the Sr cations occupy the nominal B-sites of the perovskite-type PZT host lattice. This result was supported by EXAFS analyses of both a canonical SrTiO{sub 3} perovskite and two SNO model and reference compounds. Fit models that do not account for Sr cations on B-sites were ruled out. A clear Sr-Pb peak in Fourier transformed EXAFS data visually confirmed this structural model. The generation of temporary oxygen vacancies and the intricate defect chemistry induced by SNO-doping of PZT are crucial for the exceptional materials properties exhibited by PZT:SNO materials.

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

    International Nuclear Information System (INIS)

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

    2006-01-01

    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) 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) 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

  9. Old and new ideas in ferroelectric liquid crystal technology

    Science.gov (United States)

    Lagerwall, Sven T.; Matuszczyk, M.; Matuszczyk, T.

    1998-02-01

    Ferroelectric liquid crystals (FLC) are to conventional liquid crystal what Gallium Arsenide is to Silicon in the semiconductor area. The first generation of FLC displays in now present on the market and has some outstanding features based on the symmetric bistability which may be achieved in these materials. One of the greatest challenges for the next generation is to achieve an analog grey scale out of an essentially digital principle. We will analyze in some detail which major problems had to be solved to reach the present state and show how the final steps could be taken toward a new state-of-the-art level in liquid crystal devices. In the last decade university research and industrial R and D have almost equally contributed to treat the very serious complications caused by the so-called chevron structures We will review this important topic in particular detail.

  10. Photonic guiding structures in lithium niobate crystals produced by energetic ion beams

    Science.gov (United States)

    Chen, Feng

    2009-10-01

    A range of ion beam techniques have been used to fabricate a variety of photonic guiding structures in the well-known lithium niobate (LiNbO3 or LN) crystals that are of great importance in integrated photonics/optics. This paper reviews the up-to-date research progress of ion-beam-processed LiNbO3 photonic structures and reports on their fabrication, characterization, and applications. Ion beams are being used with this material in a wide range of techniques, as exemplified by the following examples. Ion beam milling/etching can remove the selected surface regions of LiNbO3 crystals via the sputtering effects. Ion implantation and swift ion irradiation can form optical waveguide structures by modifying the surface refractive indices of the LiNbO3 wafers. Crystal ion slicing has been used to obtain bulk-quality LiNbO3 single-crystalline thin films or membranes by exfoliating the implanted layer from the original substrate. Focused ion beams can either generate small structures of micron or submicron dimensions, to realize photonic bandgap crystals in LiNbO3, or directly write surface waveguides or other guiding devices in the crystal. Ion beam-enhanced etching has been extensively applied for micro- or nanostructuring of LiNbO3 surfaces. Methods developed to fabricate a range of photonic guiding structures in LiNbO3 are introduced. Modifications of LiNbO3 through the use of various energetic ion beams, including changes in refractive index and properties related to the photonic guiding structures as well as to the materials (i.e., electro-optic, nonlinear optic, luminescent, and photorefractive features), are overviewed in detail. The application of these LiNbO3 photonic guiding structures in both micro- and nanophotonics are briefly summarized.

  11. Conversion of broadband IR radiation and structural disorder in lithium niobate single crystals with low photorefractive effect

    Science.gov (United States)

    Litvinova, Man Nen; Syuy, Alexander V.; Krishtop, Victor V.; Pogodina, Veronika A.; Ponomarchuk, Yulia V.; Sidorov, Nikolay V.; Gabain, Aleksei A.; Palatnikov, Mikhail N.; Litvinov, Vladimir A.

    2016-11-01

    The conversion of broadband IR radiation when the noncritical phase matching condition is fulfilled in lithium niobate (LiNbO3) single crystals with stoichiometric (R = Li/Nb = 1) and congruent (R = 0.946) compositions, as well as in congruent single crystals doped with zinc has been investigated. It is shown that the spectrum parameters of converted radiation, such as the conversion efficiency, spectral width and position of maximum, depend on the ordering degree of structural units of the cation sublattice along the polar axis of crystal.

  12. Complex capacitance in the representation of modulus of the lithium niobate crystals

    International Nuclear Information System (INIS)

    Alim, Mohammad A.; Batra, A.K.; Bhattacharjee, Sudip; Aggarwal, M.D.

    2011-01-01

    The lithium niobate (LiNbO 3 or LN) single crystal is grown in-house. The ac small-signal electrical characterization is conducted over a temperature range 35≤T≤150 o C as a function of measurement frequency (10≤f≤10 6 Hz). Meaningful observation is noted only in a narrow temperature range 59≤T≤73 o C. These electrical data when analyzed via complex plane formalisms revealed single semicircular relaxation both in the complex capacitance (C * ) and in the modulus (M * ) planes. The physical meaning of this kind of observation is obtained on identifying the relaxation type, and then incorporating respective equivalent circuit model. The simplistic non-blocking nature of the equivalent circuit model obtained via M * -plane is established as the lumped relaxation is identified in the C * -plane. The feature of the eventual equivalent circuit model allows non-blocking aspect for the LN crystal attributing to the presence of the operative dc conduction process. Identification of this leakage dc conduction via C * -plane is portrayed in the M * -plane where the blocking nature is removed. The interacting interpretation between these two complex planes is successfully presented.

  13. Are lithium niobate (LiNbO{sub 3}) and lithium tantalate (LiTaO{sub 3}) ferroelectrics bioactive?

    Energy Technology Data Exchange (ETDEWEB)

    Vilarinho, Paula Maria, E-mail: paula.vilarinho@ua.pt; Barroca, Nathalie; Zlotnik, Sebastian; Félix, Pedro; Fernandes, Maria Helena

    2014-06-01

    The use of functional materials, such as ferroelectrics, as platforms for tissue growth in situ or ex situ, is new and holds great promise. But the usage of materials in any bioapplication requires information on biocompatibility and desirably on bioactive behavior when bone tissue engineering is envisaged. Both requirements are currently unknown for many ferroelectrics. Herein the bioactivity of LiNbO{sub 3} and LiTaO{sub 3} is reported. The formation of apatite-like structures on the surface of LiNbO{sub 3} and LiTaO{sub 3} powders after immersion in simulated body fluid (SBF) for different soaking periods indicates their bioactive potential. The mechanism of apatite formation is suggested. In addition, the significant release of lithium ions from the ferroelectric powders in the very first minutes of soaking in SBF is examined and ways to overcome this likely hurdle addressed. - Highlights: • LiNbO{sub 3} and LiTaO{sub 3} are bioactive ferroelectrics. • Cauliflower apatite type structures indicative of in-vitro bioactivity of LiNbO{sub 3} and LiTaO{sub 3.} • Negative surface charges anchor Ca{sup 2+} to which PO{sub 4}{sup 3−} attracts forming apatite structure nuclei. • Use of ferroelectrics as platforms for tissue growth in situ or ex situ is new and holds great promise.

  14. Piezoelectricity of a ferroelectric liquid crystal with a glass transition.

    Science.gov (United States)

    Jákli, A; Tóth-Katona, T; Scharf, T; Schadt, M; Saupe, A

    2002-07-01

    Pressure-electric (hydrostatic piezoelectric) measurements are reported on bookshelf textures of a ferroelectric smectic-C (Sm C*) liquid crystal with a glass transition. The continuous variation of a partially fluid state to the solid glass enables one to trace how the piezoelectric effect depends on the consistency of the material. It was observed that in the Sm C* samples with poled glass the piezoelectric constants are comparable to conventional piezoelectric crystals and poled piezoelectric polymers. This implies their application possibilities. The magnitude of the piezoelectric constant in the glassy state depends very much on the poling conditions. The studies indicate that there are two counteracting effects, which cancel each other out in the Sm C* phase near the glass transition. Our analysis indicates that the pressure-induced director tilt change has a dominating effect both in the fluid and the glassy Sm C* states.

  15. Linear diffraction of light waves on periodically poled domain structures in lithium niobate crystals: collinear, isotropic, and anisotropic geometries

    International Nuclear Information System (INIS)

    Shandarov, S M; Mandel, A E; Akylbaev, T M; Borodin, M V; Savchenkov, E N; Smirnov, S V; Akhmatkhanov, A R; Shur, V Ya

    2017-01-01

    The possible variants of experimental observation of light diffraction on periodically poled domain structures (PPDS) in the lithium niobate crystal with 180-degree domain Y-walls are considered. We experimentally investigated isotropic and anisotropic diffraction of coherent light (λ = 655nm) on the PPDS with spatial period Λ = 8.79 μm produced by poling method in a LiNbO 3 : 5% MgO crystal. The central wavelength of irradiation experiencing a collinear diffraction on these PPDS is estimated as λ c = 455 nm. (paper)

  16. Anisotropic surface acoustic waves in tungsten/lithium niobate phononic crystals

    Science.gov (United States)

    Sun, Jia-Hong; Yu, Yuan-Hai

    2018-02-01

    Phononic crystals (PnC) were known for acoustic band gaps for different acoustic waves. PnCs were already applied in surface acoustic wave (SAW) devices as reflective gratings based on the band gaps. In this paper, another important property of PnCs, the anisotropic propagation, was studied. PnCs made of circular tungsten films on a lithium niobate substrate were analyzed by finite element method. Dispersion curves and equal frequency contours of surface acoustic waves in PnCs of various dimensions were calculated to study the anisotropy. The non-circular equal frequency contours and negative refraction of group velocity were observed. Then PnC was applied as an acoustic lens based on the anisotropic propagation. Trajectory of SAW passing PnC lens was calculated and transmission of SAW was optimized by selecting proper layers of lens and applying tapered PnC. The result showed that PnC lens can suppress diffraction of surface waves effectively and improve the performance of SAW devices.

  17. Liquid crystals with novel terminal chains as ferroelectric liquid crystal hosts

    International Nuclear Information System (INIS)

    Cosquer, G.Y.

    2000-02-01

    Changes to the molecular structure of liquid crystals can have a significant effect upon their mesomorphism and ferroelectric properties. Most of the research in liquid crystal for display applications concentrates on the design and synthesis of novel mesogenic cores to which straight terminal alkyl or alkoxy chains are attached. However, little is known about the effects upon the mesomorphism and ferroelectric properties of varying the terminal chains. The compounds prepared in this work have a common core - a 2,3-difluoroterphenyl unit with a nine-atom alkyl (nonyl) or alkoxy (octyloxy) chain at the 4-position, but with an unusual chain at the 4''-position. In some cases the terminal chain contains hetero atoms such as silicon, oxygen, chlorine and bromine or has a bulky end group. In total 46 final materials were synthesised in an attempt to understand the effect of an unusual terminal chains on mesomorphism and for some of these compounds the effect upon the switching times when added to a standard ferroelectric mixture were investigated. It was found that most compounds containing a bulky end group only displayed a smectic C phase, compounds with a halogen substituent as an end unit displayed a smectic A phase and that increasing the chain flexibility by introducing an oxygen atom in the chain reduces the melting and clearing points. The electro-optical measurements carried out on ferroelectric mixtures containing a bulky end group compound showed that shorter switching times were produced than for the ferroelectric mixture containing a straight chain compound. It is suggested that a bulky end group diminishes te extent of interlayer mixing in the chiral smectic C phase and therefore the molecules move more easily with ferroelectric switching. (author)

  18. The origin of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution crystals

    Energy Technology Data Exchange (ETDEWEB)

    Li, Fei; Zhang, Shujun; Yang, Tiannan; Xu, Zhuo; Zhang, Nan; Liu, Gang; Wang, Jianjun; Wang, Jianli; Cheng, Zhenxiang; Ye, Zuo-Guang; Luo, Jun; Shrout, Thomas R.; Chen, Long-Qing (Penn); (Xian Jiaotong); (CIW); (Simon); (TRS Techn); (Wollongong)

    2016-12-19

    The discovery of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution single crystals is a breakthrough in ferroelectric materials. A key signature of relaxor-ferroelectric solid solutions is the existence of polar nanoregions, a nanoscale inhomogeneity, that coexist with normal ferroelectric domains. Despite two decades of extensive studies, the contribution of polar nanoregions to the underlying piezoelectric properties of relaxor ferroelectrics has yet to be established. Here we quantitatively characterize the contribution of polar nanoregions to the dielectric/piezoelectric responses of relaxor-ferroelectric crystals using a combination of cryogenic experiments and phase-field simulations. The contribution of polar nanoregions to the room-temperature dielectric and piezoelectric properties is in the range of 50–80%. A mesoscale mechanism is proposed to reveal the origin of the high piezoelectricity in relaxor ferroelectrics, where the polar nanoregions aligned in a ferroelectric matrix can facilitate polarization rotation. This mechanism emphasizes the critical role of local structure on the macroscopic properties of ferroelectric materials.

  19. The origin of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution crystals.

    Science.gov (United States)

    Li, Fei; Zhang, Shujun; Yang, Tiannan; Xu, Zhuo; Zhang, Nan; Liu, Gang; Wang, Jianjun; Wang, Jianli; Cheng, Zhenxiang; Ye, Zuo-Guang; Luo, Jun; Shrout, Thomas R; Chen, Long-Qing

    2016-12-19

    The discovery of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution single crystals is a breakthrough in ferroelectric materials. A key signature of relaxor-ferroelectric solid solutions is the existence of polar nanoregions, a nanoscale inhomogeneity, that coexist with normal ferroelectric domains. Despite two decades of extensive studies, the contribution of polar nanoregions to the underlying piezoelectric properties of relaxor ferroelectrics has yet to be established. Here we quantitatively characterize the contribution of polar nanoregions to the dielectric/piezoelectric responses of relaxor-ferroelectric crystals using a combination of cryogenic experiments and phase-field simulations. The contribution of polar nanoregions to the room-temperature dielectric and piezoelectric properties is in the range of 50-80%. A mesoscale mechanism is proposed to reveal the origin of the high piezoelectricity in relaxor ferroelectrics, where the polar nanoregions aligned in a ferroelectric matrix can facilitate polarization rotation. This mechanism emphasizes the critical role of local structure on the macroscopic properties of ferroelectric materials.

  20. Ferroelectric BaTiO3 and LiNbO3 Nanoparticles Dispersed in Ferroelectric Liquid Crystal Mixtures: Electrooptic and Dielectric (Postprint)

    Science.gov (United States)

    2016-10-14

    strength for non- doped LF4 and LiNbO3/LF4 nanocolloids at temperature 30C. 146 R. K . SHUKLA ET AL. 6 Distribution A. Approved for public release (PA...AFRL-RX-WP-JA-2017-0210 FERROELECTRIC BaTiO3 AND LiNbO3 NANOPARTICLES DISPERSED IN FERROELECTRIC LIQUID CRYSTAL MIXTURES: ELECTROOPTIC...COMMAND UNITED STATES AIR FORCE Ferroelectric BaTiO3 and LiNbO3 nanoparticles dispersed in ferroelectric liquid crystal mixtures: Electrooptic and

  1. A Review of Domain Modelling and Domain Imaging Techniques in Ferroelectric Crystals

    Directory of Open Access Journals (Sweden)

    John E. Huber

    2011-02-01

    Full Text Available The present paper reviews models of domain structure in ferroelectric crystals, thin films and bulk materials. Common crystal structures in ferroelectric materials are described and the theory of compatible domain patterns is introduced. Applications to multi-rank laminates are presented. Alternative models employing phase-field and related techniques are reviewed. The paper then presents methods of observing ferroelectric domain structure, including optical, polarized light, scanning electron microscopy, X-ray and neutron diffraction, atomic force microscopy and piezo-force microscopy. Use of more than one technique for unambiguous identification of the domain structure is also described.

  2. Ferroelectricity and Piezoelectricity in Free-Standing Polycrystalline Films of Plastic Crystals.

    Science.gov (United States)

    Harada, Jun; Yoneyama, Naho; Yokokura, Seiya; Takahashi, Yukihiro; Miura, Atsushi; Kitamura, Noboru; Inabe, Tamotsu

    2018-01-10

    Plastic crystals represent a unique compound class that is often encountered in molecules with globular structures. The highly symmetric cubic crystal structure of plastic crystals endows these materials with multiaxial ferroelectricity that allows a three-dimensional realignment of the polarization axes of the crystals, which cannot be achieved using conventional molecular ferroelectric crystals with low crystal symmetry. In this work, we focused our attention on malleability as another characteristic feature of plastic crystals. We have synthesized the new plastic/ferroelectric ionic crystals tetramethylammonium tetrachloroferrate(III) and tetramethylammonium bromotrichloroferrate(III), and discovered that free-standing translucent films can be easily prepared by pressing powdered samples of these compounds. The thus obtained polycrystalline films exhibit ferroelectric polarization switching and a relatively large piezoelectric response at room temperature. The ready availability of functional films demonstrates the practical utility of such plastic/ferroelectric crystals, and considering the vast variety of possible constituent cations and anions, a wide range of applications should be expected for these unique and attractive functional materials.

  3. Using a helium--neon laser to convert infrared radiation to visible emission on lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Aurtyunyan, E.A.; Kostanyan, R.B.; Mkrtchyan, V.S.; Mkrtchyan, M.A.

    1975-01-01

    The conversion of infrared emission to the visible region was investigated by mixing with helium-neon laser emission in lithium niobate crystals. The infrared source was a Globar, and the laser was the LG-75. Emission of the sum frequencies was filtered out. The spectral composition of the converted radiation was analyzed by the ISP-51 spectrograph with an FEU-79 photomultiplier at the output. The amplified photomultiplier signal was recorded by the ChZ-33 frequency meter. By varying the angle between the optical axis of the crystal and the incident emission, infrared radiation in the 1.75 to 3.3 ..mu..m wavelength band could be converted to visible emission. It is suggested that measurement of the wavelength of converted emission might be used to study the distribution of concentration nonhomogeneities in crystals.

  4. Fatigue effect in ferroelectric crystals: Growth of the frozen domains

    Science.gov (United States)

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

    2012-06-01

    The model of the fatigue effect during cyclic switching caused by growth of the frozen domain area with charged domain walls has been proposed. It was claimed on the basis of the previous experimental results that for switching in increasing field the frozen domain area started to grow at the given sub-threshold field value and stopped at the threshold field. The influence of the shape and frequency of the field pulses used for cyclic switching has been considered. The uniaxial ferroelectric stoichiometric lithium tantalate single crystals produced by vapor transport equilibration with record low value of coercive field have been chosen as a model material for experimental verification of the model. The formation of the charged domain walls as a result of cyclic switching has been revealed by analysis of the domain images obtained by optical and Raman confocal microscopy. It has been shown that the fatigue degree is equal to the fraction of the frozen domain area. The experimental dependence of the switched charge on the cycle number has been successfully fitted by modified Kolmogorov-Avrami formula. The experimentally observed frequency independence of fatigue profile for rectangular pulses and frequency dependence for triangular pulses has been explained by proposed model.

  5. First principles study of CaTIO3 crystal in paraelectric and ferroelectric phases

    International Nuclear Information System (INIS)

    Hashemi, H.; Kompany, A.; Hosseini, M.

    2005-01-01

    Electronic properties of CaTiO 3 crystal in paraelectric and ferroelectric phases have been studied by first principles, using Hohenberg-kohn-sham density functional theory. In paraelectric phase the results show an indirect band gap of about at 2eV at Γ-R direction in the Brillouin zone and a strong hybridization between Ti-3d an O-2P orbital. In ferroelectric phase a direct band gap of about 1 eV is seen at ***Γ point. Up to our knowledge no data has been reported on the ferroelectric phase so far, therefore our results might be useful for the future works

  6. Self-templated synthesis of single-crystal and single-domain ferroelectric nanoplates

    KAUST Repository

    Chao, Chunying; Ren, Zhaohui; Zhu, Yihan; Xiao, Zhen; Liu, Zhenya; Xú , Gang; Mai, Jiangquan; Li, Xiang; Shen, Ge; Han, Gaorong

    2012-01-01

    Free-standing single-crystal PbTiO 3 nanoplates (see picture) were synthesized by a facile hydrothermal method. A "self-templated" crystal growth is presumed to lead to the formation of the PbTiO 3 nanoplates, which have ferroelectric single

  7. Biaxial potential of surface-stabilized ferroelectric liquid crystals

    Science.gov (United States)

    Kaznacheev, Anatoly; Pozhidaev, Evgeny; Rudyak, Vladimir; Emelyanenko, Alexander V.; Khokhlov, Alexei

    2018-04-01

    A biaxial surface potential Φs of smectic-C* surface-stabilized ferroelectric liquid crystals (SSFLCs) is introduced in this paper to explain the experimentally observed electric-field dependence of polarization P˜cell(E ) , in particular the shape of the static hysteresis loops. Our potential consists of three independent parts. The first nonpolar part Φn describes the deviation of the prime director n (which is the most probable orientation of the long molecular axes) from the easy alignment axis R , which is located in the boundary surface plane. It is introduced in the same manner as the uniaxial Rapini potential. The second part Φp of the potential is a polar term associated with the presence of the polar axis in a FLC. The third part Φm relates to the inherent FLC biaxiality, which has not been taken into consideration previously. The Φm part takes into account the deviations of the secondary director m (which is the most probable orientation of the short molecular axes) from the normal to the boundary surface. The overall surface potential Φs, which is a sum of Φn,Φp , and Φm, allows one to model the conditions when either one, two, or three minima of the SSFLC cell free energy are realized depending on the biaxiality extent. A monodomain or polydomain structure, as well as the bistability or monostability of SSFLC cells, depends on the number of free-energy minima, as confirmed experimentally. In this paper, we analyze the biaxiality impact on the FLC alignment. We also answer the question of whether the bistable or monostable structure can be formed in an SSFLC cell. Our approach is essentially based on a consideration of the biaxial surface potential, while the uniaxial surface potential cannot adequately describe the experimental observations in the FLC.

  8. Non-Resonant Magnetoelectric Energy Harvesting Utilizing Phase Transformation in Relaxor Ferroelectric Single Crystals

    Directory of Open Access Journals (Sweden)

    Peter Finkel

    2015-12-01

    Full Text Available Recent advances in phase transition transduction enabled the design of a non-resonant broadband mechanical energy harvester that is capable of delivering an energy density per cycle up to two orders of magnitude larger than resonant cantilever piezoelectric type generators. This was achieved in a [011] oriented and poled domain engineered relaxor ferroelectric single crystal, mechanically biased to a state just below the ferroelectric rhombohedral (FR-ferroelectric orthorhombic (FO phase transformation. Therefore, a small variation in an input parameter, e.g., electrical, mechanical, or thermal will generate a large output due to the significant polarization change associated with the transition. This idea was extended in the present work to design a non-resonant, multi-domain magnetoelectric composite hybrid harvester comprised of highly magnetostrictive alloy, [Fe81.4Ga18.6 (Galfenol or TbxDy1-xFe2 (Terfenol-D], and lead indium niobate–lead magnesium niobate–lead titanate (PIN-PMN-PT domain engineered relaxor ferroelectric single crystal. A small magnetic field applied to the coupled device causes the magnetostrictive element to expand, and the resulting stress forces the phase change in the relaxor ferroelectric single crystal. We have demonstrated high energy conversion in this magnetoelectric device by triggering the FR-FO transition in the single crystal by a small ac magnetic field in a broad frequency range that is important for multi-domain hybrid energy harvesting devices.

  9. Enhanced Cherenkov phase matching terahertz wave generation via a magnesium oxide doped lithium niobate ridged waveguide crystal

    Directory of Open Access Journals (Sweden)

    K. Takeya

    2017-01-01

    Full Text Available When combined with a nonlinear waveguide crystal, Cherenkov phase matching allows for highly effective generation of high power and broadband terahertz (THz waves. Using a ridged Lithium Niobate (LiNbO3 waveguide coupled with a specially designed silicon lens, we successfully generated THz waves with intensity of approximately three orders of magnitude stronger than those from conventional photoconductive antenna. The broadband spectrum was from 0.1 THz to 7 THz with a maximum dynamic range of 80 dB. The temporal shape of time domain pulse is a regular single cycle which could be used for high depth resolution time of flight tomography. The generated THz wave can also be easily monitored by compact room-temperature THz camera, enabling us to determine the spatial characteristics of the THz propagation.

  10. Control of coercive field in lithium niobate crystals with repeated polarization reversal

    International Nuclear Information System (INIS)

    Ro, Jung Hoon; Jeong, Doun; Park, Taeyong; Kim, Chulhan; Kwon, Soon-Bok; Cha, Myoungsik; Choi, Byeong Cheol; Yu, Nanei; Kurimura, Sunao; Jeon, Gyerok

    2005-01-01

    In this study, the amount of decrease in coercive field of congruent lithium niobate during repeated poling and back-poling was measured. The polarization is reversed in 300 ms and then back-poled during the rest period. The coercive field can be decreased around 1 kV/mm with a repeated poling interval of 5 s. As the interval prolonged, the poling field decrease became smaller, and a stretched exponential function is suggested for the experimental fitting resulting in a set of meaningful parameters. These values are essential for the design of high quality domain engineering

  11. Ferroelectric and ferroelastic domain structures in piezoelectric ceramics

    International Nuclear Information System (INIS)

    Bursill, L.A.; Julin Peng.

    1990-01-01

    A discussion of the results of conventional and high-resolution high-voltage electron microscopic studies of two ferroelectrics, barium sodium niobate and lead zirconium titanate is presented. It is shown that a rich variety of information such as ferroelectric and/or ferroelastic domains discommensurations versus antiphase boundaries, extended versus localized chemical defects and multiphase versus grain boundaries, become accessible in both single crystal and polycrystalline piezoelectrics, when a combination of high-resolution and conventional electron optical techniques is used. 15 refs., 8 figs

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

    Energy Technology Data Exchange (ETDEWEB)

    Mackwitz, P., E-mail: peterm@mail.upb.de; Rüsing, M.; Berth, G.; Zrenner, A. [Department Physik, Universität Paderborn, 33095 Paderborn (Germany); Center for Optoelectronics and Photonics Paderborn, 33095 Paderborn (Germany); Widhalm, A.; Müller, K. [Department Physik, Universität Paderborn, 33095 Paderborn (Germany)

    2016-04-11

    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/SiO{sub 2} 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. Studies of switching structures in ferroelectric liquid crystal devices

    International Nuclear Information System (INIS)

    Pabla, D.S.

    1998-01-01

    The fast, bistable electro-optic response of ferroelectric liquid crystal (FLC) devices has made them prime candidates for use in display applications. However, before these applications can become widely commercially viable a number of key issues relating to the switching within these devices need to be addressed. One of these is related to the fact that while there has been much work done on modelling the switching process in FLC devices, with some moderate success, in the main these models have not accurately accounted for the physical processes taking place. In order to rectify this situation we present a simple, multi-variable approach which includes important physical phenomenon such as stressed states, partial and domain switching. Through using this model we learn more about the dynamic molecular profiles which may exist in devices, and use this as a springboard to undertake a comprehensive theoretical and experimental study of the molecular profiles of chevron structures under different types of addressing pulses and voltages. This entails modelling the dynamic profiles using a simple non flow reorientation theory and comparing these simulations directly with experimental data obtained through the use of two different optical characterisation techniques. Our findings show quite conclusively that for monopolar addressing within low and high voltage regimes and for low voltage bipolar pulses during the early stages of switching, the dynamic reorientation near the surfaces and central regions of the device lags the reorientation within the bulk. The reverse however being true for the high voltage bipolar addressing case. These results for chevron structures differ from previous theoretical predictions made by others using equations derived from the flow coupled chiral smectic C continuum theory. These flow coupled simulations however, refer to reorientation in bookshelf structures rather than the chevron type structures thought to exist in FLC devices. As

  14. Studies of switching structures in ferroelectric liquid crystal devices

    Energy Technology Data Exchange (ETDEWEB)

    Pabla, D.S

    1998-07-01

    The fast, bistable electro-optic response of ferroelectric liquid crystal (FLC) devices has made them prime candidates for use in display applications. However, before these applications can become widely commercially viable a number of key issues relating to the switching within these devices need to be addressed. One of these is related to the fact that while there has been much work done on modelling the switching process in FLC devices, with some moderate success, in the main these models have not accurately accounted for the physical processes taking place. In order to rectify this situation we present a simple, multi-variable approach which includes important physical phenomenon such as stressed states, partial and domain switching. Through using this model we learn more about the dynamic molecular profiles which may exist in devices, and use this as a springboard to undertake a comprehensive theoretical and experimental study of the molecular profiles of chevron structures under different types of addressing pulses and voltages. This entails modelling the dynamic profiles using a simple non flow reorientation theory and comparing these simulations directly with experimental data obtained through the use of two different optical characterisation techniques. Our findings show quite conclusively that for monopolar addressing within low and high voltage regimes and for low voltage bipolar pulses during the early stages of switching, the dynamic reorientation near the surfaces and central regions of the device lags the reorientation within the bulk. The reverse however being true for the high voltage bipolar addressing case. These results for chevron structures differ from previous theoretical predictions made by others using equations derived from the flow coupled chiral smectic C continuum theory. These flow coupled simulations however, refer to reorientation in bookshelf structures rather than the chevron type structures thought to exist in FLC devices. As

  15. Dielectric properties of KDP-type ferroelectric crystals in the ...

    Indian Academy of Sciences (India)

    Hamiltonian for KDP-type ferroelectrics, expressions for field-dependent shift, width, ... For the calculation, method of statistical double-time temperature- ... roelectric phase transition and dielectric behaviour of KDP and its isomorphs is .... The dissipation of power in dielectric material can conveniently be expressed as.

  16. Bidimensional distortion in ferroelectric liquid crystals with strong ...

    Indian Academy of Sciences (India)

    characterized by bistability and optical memory in the surface-stabilized bookshelf [2,3] ... tic layers, which lies in a plane parallel to the cell walls (see figure 1). Up to now ... Theory. We consider a liquid crystalline material exhibiting ferroelectric phase organized in book- ... By applying an external electric field Eext along.

  17. Effect of amino acid doping on the growth and ferroelectric properties of triglycine sulphate single crystals

    International Nuclear Information System (INIS)

    Raghavan, C.M.; Sankar, R.; Mohan Kumar, R.; Jayavel, R.

    2008-01-01

    Effect of amino acids (L-leucine and isoleucine) doping on the growth aspects and ferroelectric properties of triglycine sulphate crystals has been studied. Pure and doped crystals were grown from aqueous solution by low temperature solution growth technique. The cell parameter values were found to significantly vary for doped crystals. Fourier transform infrared analysis confirmed the presence of functional groups in the grown crystal. Morphology study reveals that amino acid doping induces faster growth rate along b-direction leading to a wide b-plane and hence suitable for pyroelectric detector applications. Ferroelectric domain structure has been studied by atomic force microscopy and hysteresis measurements reveal an increase of coercive field due to the formation of single domain pattern

  18. Tunable double-channel filter based on two-dimensional ferroelectric photonic crystals

    International Nuclear Information System (INIS)

    Jiang, Ping; Ding, Chengyuan; Hu, Xiaoyong; Gong, Qihuang

    2007-01-01

    A tunable double-channel filter is presented, which is based on a two-dimensional nonlinear ferroelectric photonic crystal made of cerium doped barium titanate. The filtering properties of the photonic crystal filter can be tuned by adjusting the defect structure or by a pump light. The influences of the structure disorders caused by the perturbations in the radius or the position of air holes on the filtering properties are also analyzed

  19. Tunable double-channel filter based on two-dimensional ferroelectric photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Ping [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Ding, Chengyuan [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Hu, Xiaoyong [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China)]. E-mail: xiaoyonghu@pku.edu.cn; Gong, Qihuang [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China)]. E-mail: qhgong@pku.edu.cn

    2007-04-02

    A tunable double-channel filter is presented, which is based on a two-dimensional nonlinear ferroelectric photonic crystal made of cerium doped barium titanate. The filtering properties of the photonic crystal filter can be tuned by adjusting the defect structure or by a pump light. The influences of the structure disorders caused by the perturbations in the radius or the position of air holes on the filtering properties are also analyzed.

  20. Longitudinal and transverse pyroelectric effects in a chiral ferroelectric liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Yablonskii, S. V., E-mail: yablonskii2005@yandex.ru; Bondarchuk, V. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Soto-Bustamante, E. A.; Romero-Hasler, P. N. [Universidad de Chile (Chile); Ozaki, M. [Osaka University, Department of Electronic Engineering, Faculty of Engineering (Japan); Yoshino, K. [Shimane Institute for Industrial Technology (Japan)

    2015-04-15

    In this study, we compare the results of experimental investigations of longitudinal and transverse pyroelectric effects in a chiral ferroelectric crystal. In a transverse geometry, we studied freely suspended liquid-crystal films. In both geometries, samples exhibited bistability, demonstrating stable pyroelectric signals of different polarities at zero voltage. It is shown that a bistable cell based on a freely suspended film requires 40 times less energy expenditures as compared to the conventional sandwich-type cell.

  1. Improved ferroelectric and pyroelectric parameters in iminodiacetic acid doped TGS crystal

    Science.gov (United States)

    Rai, Chitharanjan; Sreenivas, K.; Dharmaprakash, S. M.

    2010-01-01

    Single crystals of Iminodiacetic acid (HN(CH 2COOH) 2) doped Triglycine sulphate (IDATGS) has been grown from aqueous solution at constant temperature by slow evaporation technique. The concentration of the dopant in the TGS solution was 2 mol%. The X-ray diffraction analysis indicates that there is significant change in the lattice parameters compared to pure TGS crystal. The IDATGS crystal has larger transition temperature and observed higher and uniform figure of merit over most part of the ferroelectric phase. These crystals also exhibit higher internal bias field and micro-hardness number compared to pure TGS. Therefore IDATGS may be a potential material for IR detectors.

  2. Flexible, ferroelectric nanoparticle doped polymer dispersed liquid crystal devices for lower switching voltage and nanoenergy generation

    Science.gov (United States)

    Nimmy John, V.; Varanakkottu, Subramanyan Namboodiri; Varghese, Soney

    2018-06-01

    Flexible polymer dispersed liquid crystal (F-PDLC) devices were fabricated using transparent conducting ITO/PET film. Polymerization induced phase separation (PIPS) method was used for pure and ferroelectric BaTiO3 (BTO) and ZnO doped PDLC devices. The distribution of nanoparticles in the PDLC and the formation of micro cavities were studied using field emission scanning electron microscopy (FESEM). It was observed that the addition of ferroelectric BTO nanoparticles has reduced the threshold voltage (Vth) and saturation voltage (Vsat) of FNP-PDLC by 85% and 41% respectively due to the spontaneous polarization of ferroelectric nanoparticles. The ferroelectric properties of BTO and ZnO in the fabricated devices were investigated using dynamic contact electrostatic force microscopy (DC EFM). Flexing the device can generate a potential due to the piezo-tribo electric effect of the ferroelectric nanomaterial doped in the PDLC matrix, which could be utilized as an energy generating system. The switching voltage after multiple flexing was also studied and found to be in par with non-flexing situations.

  3. Combined optical and electrical effects in ferroelectric crystal for high laser intensities

    Science.gov (United States)

    Kukhtarev, N. V.; Kukhtareva, T. V.; Stargell, G.; Wang, J. C.

    2009-08-01

    In this study, we have derived equations for the pyroelectric and photogalvanic contribution to the electrical charging of the photosensitive ferroelectric crystal. Standard photorefractive equations are supplemented by the equation of state for the polarization density following the Devonshire-Ginsburg-Landau (DGL) approach. The photogalvanic voltage and current is considered for a wide intensity range, which includes the CW and the pulsed photo-excitation with high intensities when the impurity is fully ionized and when the traditional linear-recombination approach is not valid. The crystal electrostatic accelerators, based on charging of ferroelectric crystals by pyroelectric and photogalvanic effects, are discussed in relation to the generation of the self-focused electron beam, X-rays, and neutrons.

  4. Fluorinated tolane and dioxane liquid crystals for ferroelectric display applications

    International Nuclear Information System (INIS)

    Chu Chuan Dong

    1994-05-01

    The aim of this thesis was to make low viscosity, low birefringence, large negative dielectric anisotropy liquid-crystalline materials for use in ferroelectric liquid crystal mixtures to be used in high speed display devices. Saturated heterocyclic rings, dioxane and dioxaborinane, were chosen separately to be linked with a difluorophenyl system as the main component of the mesogenic core. In order to optimise the physical properties and to reduce the cost of the chiral materials, the strategy of making dopant-host mixtures was used. In addition to the difluorobiphenyl dioxaborinanes, three types of compounds were prepared possessing difluorophenyl rings and a dioxane ring: (i) difluorophenyl dioxanes and difluorobiphenyl dioxanes with the fluorinated ring in the middle of or at the end of the core; (ii) a number of compounds with linking groups, dimethylene (CH 2 CH 2 ), ester (COO), ethenylene (CH=CH) and ethynylene (C≡C) between adjacent benzene rings or between a dioxane ring and a benzene ring; (iii) difluorobiphenyl dioxanes possessing a chiral aliphatic chain were chosen as chiral dopants whose structure matched those of the host materials. Other compounds which have been synthesised are the difluorotolanes and difluorophenyl-ethynyl compounds, which were targeted because of the low viscosity of the tolane compounds and the negative dielectric anisotropy of the difluorophenyl ring. Fifty-six 2-(2,3-difluorobiphenyl-4'-yl)-1,3-dioxanes (n = 5-9, m = 5-10 or O5-O9; or n = 9, R' = OCH 2 CH(CH 3 )C 4 H 9 ) were prepared. Smectic C and nematic phases were observed for most of the alkyl-alkoxy homologues. Conversely, most of the dialkyl compounds exhibited smectic C, smectic A and nematic phases. The birefringences (Δn) and the dielectric anisotropies (Δε) of a number of materials have been determined. Three 2-(2,3-difluorobiphenyl-4-yl)-5-alkyl-1,3-dioxanes (n = 7, m = O7-O9) were prepared and only exhibit nematic phases. Two difluorophenyl dioxanes were

  5. The effect of rotational viscosity on the memory effect in ferroelectric liquid crystal

    International Nuclear Information System (INIS)

    Kaur, S.; Thakur, A.K.; Chauhan, R.; Bawa, S.S.; Biradar, A.M.

    2004-01-01

    Memory effect in deformed helix ferroelectric liquid crystal (DHFLC) is not a new phenomenon. Although it was reported 12 years ago yet its exact physical behavior is not explained. It has been thought by various researchers all over the world that it might be a transient memory effect. In the present study, it has been observed and predicted that memory effect is of long duration and shows remarkable dependencies on the voltage and frequency of the driving electrical pulse, which is entirely different from the memory effect in surface-stabilized ferroelectric liquid crystal (SSFLC). The memory effect in SSFLC is primarily due to surface effect but in DHFLC, its ultra-short pitch plays a dominant role. So, it has been observed that the memory effect in DHFLC is due to its high viscosity and inter/intra layer dipolar interactions

  6. Composition, ferroelectric and antiferroelectric ordering in Pb2InNbO6 crystals

    International Nuclear Information System (INIS)

    Bokov, A.A.; Raevskij, I.P.; Smotrakov, V.G.

    1984-01-01

    Effect of thermal treatment on temperatures of phase transitions and electrical properties has been studied in Pb 2 InNbO 6 crystals with the high-temperature phase transition of the order-disorder type in In and Nb cations disposition in crystallographic positions. The order-disorder transition temperature (Tsub(t) approximately 1020 deg C) has been directly determined for the first time using the method of electric conductivity investigation. It has been shown that Pb 2 InNbO 6 in the ordered state represents the antiferroelectric material with the Curie point of 195 deg C, and it represents the ferroelectric material with a smeared transition to the paraelectric phase in the temperature range of 60 deg C in the disordered state. With temperature decrease crystals with the mean ordering degree-paraelectric phase pass to the antiferroelectric phase and then to the ferroelectric phase

  7. Advances in the Growth and Characterization of Relaxor-PT-Based Ferroelectric Single Crystals

    Directory of Open Access Journals (Sweden)

    Jun Luo

    2014-07-01

    Full Text Available Compared to Pb(Zr1−xTixO3 (PZT polycrystalline ceramics, relaxor-PT single crystals offer significantly improved performance with extremely high electromechanical coupling and piezoelectric coefficients, making them promising materials for piezoelectric transducers, sensors and actuators. The recent advances in crystal growth and characterization of relaxor-PT-based ferroelectric single crystals are reviewed in this paper with emphases on the following topics: (1 the large crystal growth of binary and ternary relaxor-PT-based ferroelectric crystals for commercialization; (2 the composition segregation in the crystals grown from such a solid-solution system and possible solutions to reduce it; (3 the crystal growth from new binary and ternary compositions to expand the operating temperature and electric field; (4 the crystallographic orientation dependence and anisotropic behaviors of relaxor-PT-based ferroelectriccrystals; and (5 the characterization of the dielectric, elastic and piezoelectric properties of the relaxor-PT-based ferroelectriccrystals under small and large electric fields.

  8. Image plane digital holographic microscope for the inspection of ferroelectric single crystals.

    Czech Academy of Sciences Publication Activity Database

    Psota, Pavel; Mokrý, Pavel; Lédl, Vít; Vojtíšek, Petr

    2016-01-01

    Roč. 55, č. 12 (2016), č. článku 121731. ISSN 0091-3286 R&D Projects: GA ČR(CZ) GA14-32228S Institutional support: RVO:61389021 Keywords : Digital holography * barium titanate * domain pattern * ferroelectric crystals * holographic microscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.082, year: 2016 http://dx.doi.org/10.1117/1.OE.55.12.121731

  9. Characterizing new compositions of [001]C relaxor ferroelectric single crystals using a work-energy model

    Science.gov (United States)

    Gallagher, John A.

    2016-04-01

    The desired operating range of ferroelectric materials with compositions near the morphotropic phase boundary is limited by field induced phase transformations. In [001]C cut and poled relaxor ferroelectric single crystals the mechanically driven ferroelectric rhombohedral to ferroelectric orthorhombic phase transformation is hindered by antagonistic electrical loading. Instability around the phase transformation makes the current experimental technique for characterization of the large field behavior very time consuming. Characterization requires specialized equipment and involves an extensive set of measurements under combined electrical, mechanical, and thermal loads. In this work a mechanism-based model is combined with a more limited set of experiments to obtain the same results. The model utilizes a work-energy criterion that calculates the mechanical work required to induce the transformation and the required electrical work that is removed to reverse the transformation. This is done by defining energy barriers to the transformation. The results of the combined experiment and modeling approach are compared to the fully experimental approach and error is discussed. The model shows excellent predictive capability and is used to substantially reduce the total number of experiments required for characterization. This decreases the time and resources required for characterization of new compositions.

  10. New ways for the optimization of the photorefractive response of lithium niobate crystals

    International Nuclear Information System (INIS)

    Luennemann, M.

    2003-11-01

    In the framework of this thesis three different approaches for the increasement of the photorefractive response of LiNbO 3 crystals are pursued: First an extremely large external electric field is applied as additional charge driver in order to support the photorefractive process and to improve the characteristic quantities. Furthermore the photorefractive properties of LiNbO 3 crystals doped with manganese are studied, because iron-doped crystals exhibit a relatively low practical upper limit of the doping concentration. The third approach for the optimization of the photorefractive response in LiNbO 3 crystals is the sensibilization of LiNbO 3 :Fe for infrared light by a temperature-dependent absorption change

  11. High Performance Relaxor-Based Ferroelectric Single Crystals for Ultrasonic Transducer Applications

    Directory of Open Access Journals (Sweden)

    Yan Chen

    2014-07-01

    Full Text Available Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3O3-PbTiO3 (PMN-PT have drawn much attention in the ferroelectric field because of their excellent piezoelectric properties and high electromechanical coupling coefficients (d33~2000 pC/N, kt~60% near the morphotropic phase boundary (MPB. Ternary Pb(In1/2Nb1/2O3-Pb(Mg1/3Nb2/3O3-PbTiO3 (PIN-PMN-PT single crystals also possess outstanding performance comparable with PMN-PT single crystals, but have higher phase transition temperatures (rhombohedral to tetragonal Trt, and tetragonal to cubic Tc and larger coercive field Ec. Therefore, these relaxor-based single crystals have been extensively employed for ultrasonic transducer applications. In this paper, an overview of our work and perspectives on using PMN-PT and PIN-PMN-PT single crystals for ultrasonic transducer applications is presented. Various types of single-element ultrasonic transducers, including endoscopic transducers, intravascular transducers, high-frequency and high-temperature transducers fabricated using the PMN-PT and PIN-PMN-PT crystals and their 2-2 and 1-3 composites are reported. Besides, the fabrication and characterization of the array transducers, such as phased array, cylindrical shaped linear array, high-temperature linear array, radial endoscopic array, and annular array, are also addressed.

  12. Electro-optic tunable multi-channel filter in two-dimensional ferroelectric photonic crystals

    International Nuclear Information System (INIS)

    Fu, Yulan; Zhang, Jiaxiang; Hu, Xiaoyong; Gong, Qihuang

    2010-01-01

    An electro-optic tunable multi-channel filter is presented, which is based on a two-dimensional ferroelectric photonic crystal made of barium titanate. The filtering properties of the photonic crystal filter can be tuned by an applied voltage or by adjusting the structural parameters. The channel shifts about 30 nm under excitation of an applied voltage of 54.8 V. The influences of the structural disorders caused by the perturbations in the radius or the position of air holes on the filtering properties are also analyzed

  13. Self-templated synthesis of single-crystal and single-domain ferroelectric nanoplates

    KAUST Repository

    Chao, Chunying

    2012-08-15

    Free-standing single-crystal PbTiO 3 nanoplates (see picture) were synthesized by a facile hydrothermal method. A "self-templated" crystal growth is presumed to lead to the formation of the PbTiO 3 nanoplates, which have ferroelectric single-domain structures, whose polarization areas can be manipulated by writing and reading. The nanoplates are also effective catalysts for the oxidation of carbon monoxide. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Pulsed Traveling-wave Quadrature Squeezing Using Quasi-phase Matched Lithium Niobate Crystals

    Science.gov (United States)

    Chen, Chao-Hsiang

    Interests in generating higher quantum noise squeezing in order to develop methods to enhance optical measurement below the shot-noise limit in various applications has grown in recent years. The noise suppression from squeezing can improve the SNR in coherent optical systems when the returning signal power is weak, such as optical coherence tomography, LADAR, confocal microscopy and low-light coherent imaging. Unlike the generation of squeezing with a continuous wave, which is currently developed mainly for gravitational wave detection in LIGO project, the study of pulsed-traveling waves is focused on industrial, medical and other commercial interests. This dissertation presents the experimental results of pulsed traveling wave squeezing. The intention of the study is to explore the possibility of using quasi-phase matched crystals to generate the highest possible degree of quadrature squeezing. In order to achieve this goal, efforts to test the various effects from spatial Gaussian modes and relative beam waist placement for the second-harmonic pump were carried out in order to further the understanding of limiting factors to pulsed traveling wave squeezing. 20mm and 30mm-long periodically poled lithium noibate (PPLN) crystals were used in the experiment to generate a squeezed vacuum state. A maximum of 4.2+/-0.2dB quadrature squeezing has been observed, and the measured anti-squeezing exceeds 20dB.The phase sensitive amplification (PSA) gain and de-gain performance were also measured to compare the results of measured squeezing. The PPLN crystals can produce high conversion efficiency of second-harmonic generation (SHG) without a cavity. When a long PPLN crystal is used in a squeezer, the beam propagation in the nonlinear medium does not follow the characteristics in thin crystals. Instead, it is operated under the long-crystal criteria, which the crystal length is multiple times longer than the Rayleigh range of the injected beam i n the crystals. Quasi

  15. Optical properties of mesoporous photonic crystals, filled with dielectrics, ferroelectrics and piezoelectrics

    Directory of Open Access Journals (Sweden)

    V. S. Gorelik

    2017-12-01

    Full Text Available At present, it is very important to create new types of mirrors, nonlinear light frequency transformers and optical filters with controlled optical properties. In this connection, it is of great interest to study photonic crystals. Their dielectric permittivity varies periodically in space with a period permitting Bragg diffraction of light. In this paper, we have investigated the optical properties of mesoporous three-dimensional (3D opal-type and one-dimensional (1D anodic alumina photonic crystals, filled with different dielectrics, ferroelectrics and piezoelectrics. We have compared the optical properties of initial mesoporous photonic crystals and filled with different substances. The possibility of mesoporous photonic crystals using selective narrow-band light filters in Raman scattering experiments and nonlinear mirrors has been analyzed. The electromagnetic field enhancing in the case of exciting light frequency close to the stop band edges has been established. The optical harmonics and subharmonics generation in mesoporous crystals, filled with ferroelectrics and piezoelectrics was proposed.

  16. Lithium niobate bulk crystallization promoted by CO{sub 2} laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, N.M., E-mail: nmferreira@ua.pt [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Costa, F.M. [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Nogueira, R.N. [Instituto de Telecomunicacoes, 3810-193 Aveiro (Portugal); Graca, M.P.F. [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Crystallization of LiNbO{sub 3} nanocrystals in a SiO{sub 2} matrix by CO{sub 2} laser irradiation process. Black-Right-Pointing-Pointer Samples heat-treated at 650 Degree-Sign C (4 h) and laser treated (4 W/500 s) show similar morphology. Black-Right-Pointing-Pointer Glass-ceramics produced by laser process requires a very low processing time. - Abstract: The crystallization induced by laser radiation is a very promising technique to promote glass/ceramic transformation, being already used to produce crystalline patterns on glass surfaces. In this work, a SiO{sub 2}-Li{sub 2}O-Nb{sub 2}O{sub 5} glass, prepared by the sol-gel route, was submitted to CO{sub 2} laser radiation and conventional heat-treatments in order to induce the LiNbO{sub 3} crystallization. The structure and morphology of the samples prepared by both routes was analyzed as a function of exposure time, radiation power and heat-treatment temperatures by XRD, Raman spectroscopy and SEM. The results reveal a correlation between the crystallization degree of LiNbO{sub 3} particles and glass matrix with the heat treatment type and experimental parameters. An heat-treatment at 650 Degree-Sign C/4 h was necessary to induce crystallization in heat treatments samples while 4 W/500 s was enough for laser radiation ones, corresponding a reduction time processing of {approx}14 000 s.

  17. Variation of the energy gap of the SbSI crystals at ferroelectric phase transition

    International Nuclear Information System (INIS)

    Audzijonis, A.; Zaltauskas, R.; Zigas, L.; Vinokurova, I.V.; Farberovich, O.V.; Pauliukas, A.; Kvedaravicius, A.

    2006-01-01

    Variation of the forbidden gap of SbSI crystals in the phase transition region is analyzed on the pseudopotential method for antiferroelectric and ferroelectric phase. The band gap at several special points of the Brillouin zone and some characteristic parameters of the band are considered. During the phase transition, the most significant changes are observed with the valence band top at points Q, C, R, H, E and with the conduction band bottom at points H, T and E of the Brillouin zone. At the ferroelectric phase transition, the valence and conduction bands change due to displacement of Sb and S atoms with respect to I and with respect to each other as a result of order-disorder and displacement-type transition. The obtained band gap values agree quite well with the experiment. This is apparently due to application of neutral rather than ionic atomic functions and inclusion of sufficiently many plane waves in the basis set for calculation

  18. Synchrotron X-ray topographic studies of para-ferroelectric transition in ammonium sulphate crystal

    International Nuclear Information System (INIS)

    Bhat, H.L.; Roberts, K.J.

    1993-01-01

    Ammonium sulphate undergoes a para-ferroelectric transition at 223 K. The transition is presumably first order in nature. White radiation topographic studies of this transition are presented here. The existence of pre-transition effects due to lattice deformation leading to severe strain is noticed. This sometimes resulted in dislocation generation. The well defined phase boundary observed in this crystal confirms the first order nature of this transition. The zigzag nature of the phase boundary with preferably oriented segments has been attributed to the specific properties of the strain tensors of the transition. Ferroelectric domains have also been detected by faint dynamical x-ray contrast of their images. (author). 7 refs., 1 fig

  19. Crystal Structure and Ferroelectric Properties of ε-Ga2O3 Films Grown on (0001)-Sapphire.

    Science.gov (United States)

    Mezzadri, Francesco; Calestani, Gianluca; Boschi, Francesco; Delmonte, Davide; Bosi, Matteo; Fornari, Roberto

    2016-11-21

    The crystal structure and ferroelectric properties of ε-Ga 2 O 3 deposited by low-temperature MOCVD on (0001)-sapphire were investigated by single-crystal X-ray diffraction and the dynamic hysteresis measurement technique. A thorough investigation of this relatively unknown polymorph of Ga 2 O 3 showed that it is composed of layers of both octahedrally and tetrahedrally coordinated Ga 3+ sites, which appear to be occupied with a 66% probability. The refinement of the crystal structure in the noncentrosymmetric space group P6 3 mc pointed out the presence of uncompensated electrical dipoles suggesting ferroelectric properties, which were finally demonstrated by independent measurements of the ferroelectric hysteresis. A clear epitaxial relation is observed with respect to the c-oriented sapphire substrate, with the Ga 2 O 3 [10-10] direction being parallel to the Al 2 O 3 direction [11-20], yielding a lattice mismatch of about 4.1%.

  20. Formulation of electroclinic, ferroelectric and antiferroelectric liquid crystal mixtures suitable for display devices

    Science.gov (United States)

    Debnath, Asim; Goswami, Debarghya; Mandal, Pradip Kumar

    2018-04-01

    Most of the liquid crystal display (LCD) devices starting from simplest wrist watches or calculators to complex laptops or flat TV sets are based on nematics. Although a tremendous improvement in the quality of display as well as reduction of manufacturing cost has taken place over the years, there are many issues which the LC industry is trying hard to address. Ferroelectric liquid crystals (FLC) are of current interest in the LCD industry since among various other advantages FLC based displays have micro-second order switching compared to milli-second order switching in nematic based displays. To meet the market demand much effort has been made to optimize the physical parameters of FLCs, such as temperature range, spontaneous polarization (PS), helical pitch (p), switching time (τ), tilt angle (θ) and rotational viscosity (γ). Multicomponent mixtures are, therefore, formulated to optimize all the required properties for practical applications since no single FLC compound can satisfy the above requirements. To the best of our knowledge electroclinic, ferroelectric and antiferroelectric liquid crystal mixtures have been formulated first time by any Indian group which have properties suitable for FLC based display devices and at par with mixtures used in the industry.

  1. Experimental demonstration of a ferroelectric liquid crystal tunable filter for fast demodulation of FBG sensors

    Science.gov (United States)

    Mathews, Sunish; Semenova, Yuliya; Rajan, Ginu; Farrell, Gerald

    2009-05-01

    A discretely tunable Surface-Stabilized Ferroelectric Liquid Crystal based Lyot Filter, with tuning speeds in the order of microseconds, is demonstrated experimentally as a channel dropper for the demodulation of multiple Fibre Bragg Grating sensors. The 3-stage Lyot Filter designed and experimentally verified can be used together with the high-speed ratiometric wavelength measurement system employing a fibre bend loss edge filter. Such systems can be used for the demodulation of distributed Fibre Bragg Grating sensors employed in applications such as structural monitoring, industrial sensing and haptic telerobotic surgical systems.

  2. Effect of lateral methoxy substitution on mesomorphic and structural properties of ferroelectric liquid crystals

    Czech Academy of Sciences Publication Activity Database

    Bubnov, Alexej M.; Kašpar, Miroslav; Novotná, Vladimíra; Hamplová, Věra; Glogarová, Milada; Kapernaum, N.; Giesselmann, F.

    2008-01-01

    Roč. 35, č. 11 (2008), s. 1329-1337 ISSN 0267-8292 R&D Projects: GA ČR GA202/05/0431; GA AV ČR IAA100100710 Grant - others:DAAD-ASCR(XE) D11-CZ7/06-07; DAAD-ASCR(XE) D7-CZ8/08-09 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectric liquid crystal * chiral materials * x-ray diffraction * dielectric properties * layer shrinkage * spontaneous polarisation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.132, year: 2008

  3. Electrically tunable spatially variable switching in ferroelectric liquid crystal/water system

    Science.gov (United States)

    Choudhary, A.; Coondoo, I.; Prakash, J.; Sreenivas, K.; Biradar, A. M.

    2009-04-01

    An unusual switching phenomenon in the region outside conducting patterned area in ferroelectric liquid crystal (FLC) containing about 1-2 wt % of water has been observed. The presence of water in the studied heterogeneous system was confirmed by Fourier transform infrared spectroscopy. The observed optical studies have been emphasized on the "spatially variable switching" phenomenon of the molecules in the nonconducting region of the cell. The observed phenomenon is due to diffusion of water between the smectic layers of the FLC and the interaction of the curved electric field lines with the FLC molecules in the nonconducting region.

  4. Design considerations for quasi-phase-matching in doubly resonant lithium niobate hexagonal microresonators

    CSIR Research Space (South Africa)

    Sono, Tleyane J

    2017-08-01

    Full Text Available Fabrication capabilities of high optical quality hexagonal superstructures by chemical etching of inverted ferroelectric domains in lithium niobate platform suggests a route for efficient implementation of compact hexagonal microcavities...

  5. Preparation of Lead Magnesium Niobate-Lead Zirconate Titanate Films and Their Crystallization Behaviors

    International Nuclear Information System (INIS)

    Tursiloadi, Silvester

    2002-01-01

    The thin films with composition near morpotropic phase boundary (MPB) of the system xPb(Mg 1 /3, Nb 2 /3) O 3 -yPbTiO 3 -zPbZrO 3 (x = 0-0.35, y = 0.47 and z = 0.53), were prepared by sol-gel method. The starting materials were consisted of Pb(iso-OC 3 H 7 ) 2 , Zr(n-OC 4 H 9 ) 4 , Ti(iso-OC 3 H 7 ) 4 , Mg(CH 3 COO) 2 4H 2 O and Nb(OC 2 H 5 ) 5 . The l-propanol was used as solvent. The concentration of PMN-PT-PZ in coating solution was 0.7 M, and the pH of the solution was 4.5. The thin films were prepared by dip coating and spin coating. The crystallization behaviors of the PMN-PT-PZ thin films showed that the formation of perovskite phase at low temperature becomes difficult with increasing the content of PMN. The amounts of pyrochlore and perovskite phase in PMN-PT-PZ films depended on the heating temperatures, and PMN contents. Single-phase perovskite was found for the coated films containing 0 and 12.5 mol% after calculating at 600 o C, 21 mol% after calculating at 700 o C, and 30 mol% after calculating at 750 o C. Single-phase perovskite of coated films will never be found when the content of PMN was 35 mol%

  6. Surface topography and crystal and domain structures of films of ferroelectric copolymer of vinylidene difluoride and trifluoroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Kochervinskii, V. V., E-mail: kochval@mail.ru [Karpov Institute of Physical Chemistry, Branch (Russian Federation); Kiselev, D. A.; Malinkovich, M. D. [National University of Science and Technology MISiS (Russian Federation); Korlyukov, A. A.; Lokshin, B. V. [Russian Academy of Sciences, Nesmeyanov Institute of Organoelement Compounds (Russian Federation); Volkov, V. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics” (Russian Federation); Kirakosyan, G. A. [Russian Academy of Sciences, Kurnakov Institute of General and Inorganic Chemistry (Russian Federation); Pavlov, A. S. [Karpov Institute of Physical Chemistry, Branch (Russian Federation)

    2017-03-15

    The crystallization of a copolymer from a solution at room temperature is found to lead to the formation of a metastable structure, characterized by the coexistence of ferroelectric and paraelectric phases. The fraction of the latter decreases after annealing above the Curie point. Atomic force microscopy (AFM) has revealed a difference in the surface topographies between the films contacting with air and the films contacting with a glass substrate. The microstructure of copolymer chains has been investigated by {sup 19}F NMR spectroscopy. The chain fragments with “defect” attached monomeric units are ejected to the surface. The character of the ferroelectric domains formed during crystallization and their size distribution are analyzed.

  7. Relaxor ferroelectricity, ferromagnetic and optical second harmonic properties in lanthanum lithium niobate (La0.05Li0.85NbO3) nanoparticles

    International Nuclear Information System (INIS)

    Díaz-Moreno, Carlos A.; Ding, Yu; Li, Chunqiang; Portelles, Jorge; Heiras, J.; Hurtado-Macias, A.; Farias, J.R.; González-Hernández, J.; Yacamán, M.J.

    2017-01-01

    Relaxor ferroelectricity, ferromagnetism and Second Harmonic Generation properties were founded and studied as a function of a reduction heat treatment at 650 °C in a Ar-5%H 2 atmosphere in stoichiometric La 0.05 Li 0.85 NbO 3 nanoparticles of 40 nm. A diffuse dielectric anomaly related with relaxor behavior from 25 °C to 800 °C in a frequency range from 100 Hz to 1 MHz was founded. It also shows ferromagnetic anhysterestic type and ferroelectric hysteresis loops at room temperature with a magnetic spin remnant of 2.5 × 10 −3 emu/g and polarization saturation of 0.235 μC/cm 2 , remnant polarization of 0.141 μC/cm 2 , coercive field of 1.35 kV/cm, respectively. It shows very good second harmonic generation signal at 450 nm and 500 nm. High Resolution Transmission Electron Microscopy, X-ray Photoelectron Spectroscopy and Raman spectroscopy, indicate an ABO 3 perovskite structure, new electronic binding energy structure for La (5s, 4d), Li (1s), Nb (4s, 3d, 4p) and oxygen (1s, 2s) and new vibrations modes on octahedron NbO 6 related to multiferroic single phase nanoparticles, respectively.

  8. Relaxor ferroelectricity, ferromagnetic and optical second harmonic properties in lanthanum lithium niobate (La0.05Li0.85NbO3) nanoparticles

    Science.gov (United States)

    Díaz-Moreno, Carlos A.; Ding, Yu; Li, Chunqiang; Portelles, Jorge; Heiras, J.; Hurtado-Macias, A.; Farias, J. R.; González-Hernández, J.; Yacamán, M. J.; López, Jorge

    2017-07-01

    Relaxor ferroelectricity, ferromagnetism and Second Harmonic Generation properties were founded and studied as a function of a reduction heat treatment at 650 °C in a Ar-5%H2 atmosphere in stoichiometric La0.05Li0.85NbO3 nanoparticles of 40 nm. A diffuse dielectric anomaly related with relaxor behavior from 25 °C to 800 °C in a frequency range from 100 Hz to 1 MHz was founded. It also shows ferromagnetic anhysterestic type and ferroelectric hysteresis loops at room temperature with a magnetic spin remnant of 2.5 × 10-3 emu/g and polarization saturation of 0.235 μC/cm2, remnant polarization of 0.141 μC/cm2, coercive field of 1.35 kV/cm, respectively. It shows very good second harmonic generation signal at 450 nm and 500 nm. High Resolution Transmission Electron Microscopy, X-ray Photoelectron Spectroscopy and Raman spectroscopy, indicate an ABO3 perovskite structure, new electronic binding energy structure for La (5s, 4d), Li (1s), Nb (4s, 3d, 4p) and oxygen (1s, 2s) and new vibrations modes on octahedron NbO6 related to multiferroic single phase nanoparticles, respectively.

  9. Giant Magnetoelectric Energy Conversion Utilizing Inter-Ferroelectric Phase Transformations in Ferroics

    Science.gov (United States)

    Finkel, Peter; Staruch, Margo

    Phase transition-based electromechanical transduction permits achieving a non-resonant broadband mechanical energy conversion see (Finkel et al Actuators, 5 [1] 2. (2015)) , the idea is based on generation high energy density per cycle , at least 100x of magnitude larger than linear piezoelectric type generators in stress biased [011]cut relaxor ferroelectric Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystal can generate reversible strain >0.35% at remarkably low fields (0.1 MV/m) for tens of millions of cycles. Recently we demonstrated that large strain and polarization rotation can be generated for over 40 x 106cycles with little fatigue by realization of reversible ferroelectric-ferroelectric phase transition in [011] cut PIN-PMN-PT relaxor ferroelectric single crystal while sweeping through the transition with a low applied electric field <0.18 MV/m under mechanical stress. This methodology was extended in the present work to propose magnetoelectric (ME) composite hybrid system comprised of highly magnetostrictive alloymFe81.4Ga18.6 (Galfenol), and lead indium niobate-lead magnesium niobate-lead titanate (PIN-PMN-PT) domain engineered relaxor ferroelectric single crystal. A small time-varying magnetic field applied to this system causes the magnetostrictive element to expand, and the resulting stress forces the phase change in the relaxor ferroelectric single crystal. ME coupling coefficient was fond to achieve 80 V/cm Oe near the FR-FO phase transition that is at least 100X of magnitude higher than any currently reported values.

  10. Indentation plasticity of barium titanate single crystals: Dislocation influence on ferroelectric domain walls

    Energy Technology Data Exchange (ETDEWEB)

    Liu, D. [Department of Mechanical Engineering, University of Houston, 4800 Calhoun Road, Houston, TX 77204 (United States)]. E-mail: duo.liu@mail.uh.edu; Chelf, M. [Department of Mechanical Engineering, University of Houston, 4800 Calhoun Road, Houston, TX 77204 (United States); White, K.W. [Department of Mechanical Engineering, University of Houston, 4800 Calhoun Road, Houston, TX 77204 (United States)

    2006-10-15

    The plastic behaviors of barium titanate (001) and (110) single crystals are studied with atomic force microscopy and piezoresponse force microscopy (PFM) following nanoindendation damage. Plastic deformation mechanisms of ferroelectric barium titanate single crystals are discussed with a focus on the interaction between PFM response and dislocation activities. Nanoindentation tests indicate that the theoretical strength is approached prior to the first pop-in event, consistent with the creation of dislocation nucleation sites required for the onset of plasticity. Surface topographic and piezoelectric analyses indicate that pile-ups around indents result from dislocation activities on the primary slip system, {l_brace}110{r_brace}{sub pc}<11-bar 0>{sub pc}. The more complex indentation-induced domain patterns observed on (110) barium titanate are also discussed.

  11. Indentation plasticity of barium titanate single crystals: Dislocation influence on ferroelectric domain walls

    International Nuclear Information System (INIS)

    Liu, D.; Chelf, M.; White, K.W.

    2006-01-01

    The plastic behaviors of barium titanate (001) and (110) single crystals are studied with atomic force microscopy and piezoresponse force microscopy (PFM) following nanoindendation damage. Plastic deformation mechanisms of ferroelectric barium titanate single crystals are discussed with a focus on the interaction between PFM response and dislocation activities. Nanoindentation tests indicate that the theoretical strength is approached prior to the first pop-in event, consistent with the creation of dislocation nucleation sites required for the onset of plasticity. Surface topographic and piezoelectric analyses indicate that pile-ups around indents result from dislocation activities on the primary slip system, {110} pc pc . The more complex indentation-induced domain patterns observed on (110) barium titanate are also discussed

  12. Optical properties of calcium barium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Heine, Urs; Betzler, Klaus [Department of Physics, University of Osnabrueck (Germany); Burianek, Manfred; Muehlberg, Manfred [Institute of Crystallography, University of Cologne (Germany)

    2010-07-01

    We report on optical measurements on the novel tungsten bronze type calcium barium niobate. [001]-oriented transparent and colorless single crystals were grown by the Czochralski method with dimensions of 12 mm in diameter and about 80 mm in length. With its relatively high Curie temperature of about 538 K for the congruently melting composition of 28.1 mole% calcium and its high nonlinear coefficients, CBN is a promising material for future applications. Recent experiments revealed, that the application of an external electric field of several kV/cm to CBN at room temperature leads to an increasing opacity of the sample. This might be a drawback considering the future usability of CBN in optical systems. We present investigations on the transmittance behaviour of CBN under external electric fields, demonstrating the erasement of the clouding without affecting the polarization. Experiments have been performed at temperatures ranging from room temperature to approximately 480 K. When heating up the sample, its colorless appearance changes to a light yellow, which can be attributed to a shift of the band edge to longer wavelengths with increasing temperature. To further investigate the transmittance properties of CBN, measurements of the band edge under various temperatures up to the ferroelectric phase transition have been performed.

  13. X-band EPR studies of ferroelectric lead titanate (PT), piezoelectric lead magnesium niobate (PMN), and PMN/PT powders at 10 and 85 K

    International Nuclear Information System (INIS)

    Huang, J.; Fitzgerald, J.J.; Chasteen, N.D.

    1998-01-01

    X-band EPR spectra of lead titanate (PT) and lead magnesium niobate (PMN) powders prepared by different synthetic methods and a PMN/PT powder of the composition 0.9 PMN/01 PT were obtained at 85 and 10 K. Several EPR signals due to adventitious Fe 3+ ion impurities, a signal due to the Ti 3+ ion, and a signal due to the Pb 3+ ion are observed for PT, PMN, and PMN/PT powders. The EPR signals observed at g = 2.0 and 6.0 are assigned to Fe 3+ ions in the B-sites of the perovskite lattice structure of lad titanate with axial symmetry. The EPR signals observed at g = 1.99 and 4.25 are assigned to Fe 3+ ions in the B-sites of the perovskite lattice structure of PMN and 0.9 PMN/0.1 PT materials with cubic and rhombic symmetries, respectively. The sharp EPR signal observed at g = 1.94 is assigned to Ti 3= ion for PT and 0.9 PMN/0.1 PT powders. In addition, a broader EPR signal at g = 2.28--2.30 for PMN obtained by the molten salt method is assigned to axial Pb 3+ ion sites in this PMN material. EPR results obtained here for the e 3+ ions in the B-sites of the PMN materials, in particular, suggest that both cubic and rhombic symmetry sites corresponding to a range of Nb(OMg) x (ONb) 6-x site configurations exist in the PMN. These EPR results indicate that PMN likely exists with partial B-site cation (Mg/Nb) ordering in the perovskite lattice structure

  14. Synthesis, growth, morphology and characterization of ferroelectric glycine phosphite single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Devi, K. Renuka; Srinivasan, K. [Crystal Growth Laboratory, Department of Physics, School of Physical Sciences, Bharathiar University, Tamil Nadu (India)

    2011-12-15

    Glycine phosphite (NH{sub 3}CH{sub 2}COO.H{sub 3}PO{sub 3}), a potential ferroelectric material, was grown as single crystals from aqueous solutions by slow evaporation and slow cooling methods. Laboratory synthesized title compound was purified by recrystallization method and confirmed by Fourier transform infrared and Laser Raman studies. Temperature dependent solubility in double distilled water in the range between 288 and 328 K was determined by gravimetric method. Morphological importance of various growth faces were studied by optical goniometry. Powder x-ray diffraction study performed on the grown crystals confirms the crystal system and lattice parameters of the unit cell. Optical transparency of the grown crystals in the ultraviolet-visible -near infrared region was studied by spectroscopic method. Thermal stability of the grown crystals in the temperature region above ambient until melting was studied using differential scanning calorimetry. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Nonlinear excitations and charge transport in lithium niobate crystals investigated using femtosecond-light gratings; Nichtlineare Anregungen und Ladungstransport in Lithiumniobatkristallen untersucht mit Femtosekunden-Lichtgittern

    Energy Technology Data Exchange (ETDEWEB)

    Maxein, Karl Dominik

    2009-12-15

    Lithium niobate (LiNbO{sub 3}) is a widely employed material in nonlinear optics and photonics. Its usage is hampered by the photorefractive effect, which can destroy beam profiles and phase matching conditions. Existing methods to suppress photorefraction fail for the interesting regime of very high intensities and short pulses. Therefore, the photorefractive effect is investigated using femtosecond laser pulses: By utilizing so-called 2K holography, the occupation of energetically shallow traps is observed to occur in less than 100 fs after a two-photon excitation. Writing of photorefractive gratings into oxidized iron-doped LiNbO{sub 3} is much faster with pulses than with cw light. This is explained by the sensitization of the crystal due to charge trapping in photorefractive centers after nonlinear excitations. Finally, light-induced scattering of pulse light is suppressed compared to the scattering of cw light due to the small coherence length of pulses. (orig.)

  16. Ferroelectric InMnO{sub 3}: Growth of single crystals, structure and high-temperature phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Bekheet, Maged F., E-mail: maged.bekheet@ceramics.tu-berlin.de [Fachbereich Material‐ und Geowissenschaften, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Fachgebiet Keramische Werkstoffe / Chair of Advanced Ceramic Materials, Institut für Werkstoffwissenschaften und -technologien, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin (Germany); Svoboda, Ingrid; Liu, Na [Fachbereich Material‐ und Geowissenschaften, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Bayarjargal, Lkhamsuren [Institut für Geowissenschaften, Goethe-Universität, Altenhöferallee 1, d-60438 Frankfurt a.M. (Germany); Irran, Elisabeth [Institut für Chemie, Technische Universität Berlin, Straße des 17, Juni 135, 10623 Berlin (Germany); Dietz, Christian; Stark, Robert W.; Riedel, Ralf [Fachbereich Material‐ und Geowissenschaften, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Gurlo, Aleksander [Fachgebiet Keramische Werkstoffe / Chair of Advanced Ceramic Materials, Institut für Werkstoffwissenschaften und -technologien, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin (Germany)

    2016-09-15

    To understand the origin of the ferroelectricity in InMnO{sub 3}, single crystals with average size of 1 mm were grown in PbF{sub 2} flux at 950 °C. The results of single crystal X-ray diffraction, second harmonic generation and piezoresponse force microscopy studies of high-quality InMnO{sub 3} single crystals reveal that the room-temperature state in this material is ferroelectric with P6{sub 3}cm symmetry. The polar InMnO{sub 3} specimen undergoes a reversible phase transition from non-centrosymmetric P6{sub 3}cm structure to a centrosymmetric P6{sub 3}/mmc structure at 700 °C as confirmed by the in situ high-temperature Raman spectroscopic and synchrotron X-ray diffraction experiments. - Graphical abstract: Piezoresponse fore microscopy (PFM) studies of high quality InMnO{sub 3} single crystal revealed that the room-temperature state of this material is ferroelectric with a clear cloverleaf pattern corresponding to six antiphase ferroelectric domains with alternating polarization ±P{sub z}. Display Omitted - Highlights: • InMnO{sub 3} single crystals with average size of 1 mm were grown in PbF{sub 2} flux at 950 °C. • The room-temperature state of InMnO{sub 3} is ferroelectric with polar P6{sub 3}cm structure. • PolarInMnO{sub 3} reversibly transforms to a centrosymmetric P6{sub 3}/mmc structure above 700 °C.

  17. Shock-wave compression of lithium niobate from 2.4 to 44 GPa

    International Nuclear Information System (INIS)

    Stanton, P.L.; Graham, R.A.

    1979-01-01

    Shock compression of lithium niobate above the Hugoniot elastic limit (about 2.5 GPa) reveals a succession of unusual features. Just above the Hugoniot elastic limit, the shock velocity is observed to be well below the bulk sound speed, indicative of a drastic reduction of shear strength. The shock velocity is observed to increase with particle velocity at an unusually large rate due to the reduction of strength in a very stiff material and an anomalously large pressure derivative of the bulk modulus. This later behavior may be due to the effects of localized shock heating resulting from heterogeneous shear deformation in ferroelectrics like lithium niobate and lithium tantalate in which increases in temperature are shown to have a strong effect on bulk modulus. A shock-induced polymorphic phase transition occurs at 13.9 GPa. Above the transition point the slope of the Hugoniot curve relating shock velocity and particle velocity is unusually low, indicative of a broad mixed phase region of undetermined extent. Limited work is reported on the isomorphous crystal, lithium tantalate, which exhibits features similar to lithium niobate with a Hugoniot elastic limit of 4 GPa and a phase transition in the vicinity of 19 GPa

  18. Determination of Metastable Zone Width, Induction Period and Interfacial Energy of a Ferroelectric Crystal - Potassium Ferrocyanide Trihydrate (KFCT

    Directory of Open Access Journals (Sweden)

    R. Kanagadurai

    2010-01-01

    Full Text Available An order-disorder type potassium ferrocyanide trihydrate (KFCT is a coordination compound forming lemon- yellow monoclinic ferroelectric crystals with curie temperature 251 K. KFCT crystals have been grown by temperature lowering solution growth technique. Solubility of KFCT has been determined for various temperatures. Metastable zone width, induction period and interfacial energy were determined for the aqueous solution of KFCT. Bulk crystal of potassium ferrocyanide trihydrate was grown with the optimized growth parameters. The grown crystal possesses good optical transmission in the entire UV-Visible region

  19. Behaviour of nematic liquid crystals doped with ferroelectric nanoparticles in the presence of an electric field

    Science.gov (United States)

    Emdadi, M.; Poursamad, J. B.; Sahrai, M.; Moghaddas, F.

    2018-06-01

    A planar nematic liquid crystal cell (NLC) doped with spherical ferroelectric nanoparticles is considered. Polarisation of the nanoparticles are assumed to be along the NLC molecules parallel and antiparallel to the director with equal probability. The NLC molecules anchoring to the cell walls are considered to be strong, while soft anchoring at the nanoparticles surface is supposed. Behaviour of the NLC molecules and nanoparticles in the presence of a perpendicular electric field to the NLC cell is theoretically investigated. The electric field of the nanoparticles is taken into account in the calculations. Freedericksz transition (FT) threshold field in the presence of nanoparticles is found. Then, the director and particles reorientations for the electric fields larger than the threshold field are studied. Measuring the onset of the nanoparticles reorientation is proposed as a new method for the FT threshold measurement.

  20. Dielectric and electro-optical parameters of two ferroelectric liquid crystals: a comparative study

    International Nuclear Information System (INIS)

    Kumar Misra, Abhishek; Kumar Srivastava, Abhishek; Shukla, J P; Manohar, Rajiv

    2008-01-01

    Dielectric relaxation and an electro-optical study of two ferroelectric liquid crystals having different spontaneous polarizations (Felix 16/100 and Felix 17/000) showing SmC* and SmA phases have been performed in the temperature range 30-80 compfn C. The experimental data have been used to determine different relaxation parameters, viz. distribution parameter, relaxation frequency, dielectric strength and rotational viscosity. The Goldstone mode of dielectric permittivity has been well observed for both the samples under investigation. The activation energy of both the samples has also been determined by the best theoretical fitting of the Arrhenius plot. We have also evaluated the optical response time and anchoring energy coefficients from electro-optical measurement techniques for these samples.

  1. Effect of smectic A temperature width on the soft mode in ferroelectric liquid crystals

    Science.gov (United States)

    Choudhary, A.; Kaur, S.; Prakash, J.; Sreenivas, K.; Bawa, S. S.; Biradar, A. M.

    2008-08-01

    The behavior of soft mode range with respect to the temperature width of smectic A (Sm A) phase has been studied in four different ferroelectric liquid crystal (FLC) materials in the frequency range 10Hz-10MHz. The studies have been carried out in a planarly well aligned cells at different temperatures and different bias fields in Sm C* and Sm A phases. Dielectric studies of these FLCs near Sm C*-Sm A phase transition show that the temperature range of soft mode relaxation frequency phenomenon varies with the temperature width of Sm A phase. The dependence of tilt angle on temperature shows the nature of the order of transition at Sm C*-Sm A phase. The coupling between order parameters of Sm C* and Sm A phase influences the soft mode and phase transition in Sm C* and Sm A phases.

  2. Fibonacci Sequences Quasiperiodic A5B6C7 Ferroelectric Based Photonic Crystal: FDTD analysis

    Directory of Open Access Journals (Sweden)

    S. Simsek

    2017-10-01

    Full Text Available In this study, we present an investigation of the optical properties and band structures for the conventional and Fibonacci photonic crystals (PCs based on some A5B6C7 ferroelectrics (SbSBr and BiTeCl. Here, we use one dimensional SbSBr and BiTeCl based layers in air background. We have theoretically calculated the photonic band structure and transmission spectra of SbSBr and BiTeCl based PC superlattices. The position of minima in the transmission spectrum correlates with the gaps obtained in the calculation. The intensity of the transmission depths is more intense in the case of higher refractive index contrast between the layers. In our simulation, we employed the finite-difference time domain  technique and the plane wave expansion method, which implies the solution of Maxwell equations with centered finite-difference expressions for the space and time derivatives.

  3. Fast switchable ferroelectric liquid crystal gratings with two electro-optical modes

    International Nuclear Information System (INIS)

    Ma, Ying; Srivastava, A. K.; Chigrinov, V. G.; Kwok, H.-S.; Wang, Xiaoqian

    2016-01-01

    In this article, we reveal a theoretical and experimental illustration of the Ferroelectric liquid crystal (FLC) grating fabricated by mean of patterned alignment based on photo-alignment. The complexity related to the mismatching of the predefined alignment domains on the top and bottom substrate has been avoided by incorporating only one side photo aligned substrate while the other substrate does not have any alignment layer. Depending on the easy axis in the said alignment domains and the azimuth plane of the impinging polarized light, the diffracting element can be tuned in two modes i.e. DIFF/OFF switchable and DIFF/TRANS switchable modes, which can be applied to different applications. The diffraction profile has been illustrated theoretically that fits well with the experimental finding and thus the proposed diffraction elements with fast response time and high diffraction efficiency could find application in many modern devices.

  4. Nonlinear Raman spectroscopy of liquid crystals: orientational alignment and switching behaviour in a ferroelectric liquid crystal mixture

    Science.gov (United States)

    Grofcsik, Andras

    Picosecond inverse Raman spectroscopy has been employed to probe the alignment behaviour and switching characteristics of a 6 mum thick ferroelectric liquid crystal based on a host mixture of fluorinated phenyl biphenylcarboxylates and a chiral dopant. Optical bistability is observed in the Raman signal on application of dc electric fields of opposite polarity. For particular polarities of the applied field, the Raman signals display a cos4theta dependence on the angle of rotation around the beam direction. Reorientational rate constants of 300 mus and 590 mus are observed for the aromatic core at the high-voltage limit for the rise and decay of the 1600 cm-1 Raman signal on application of a switching ac electric field.

  5. Neutron diffraction study of crystal structures of deuterated glycinium phosphite in paraelectric and ferroelectric phases

    International Nuclear Information System (INIS)

    Machida, Mitsuo; Uchida, Hiroyuki; Ishibashi, Toku; Taniguchi, Hiroki; Komukae, Masaru; Osaka, Toshio; Koyano, Nobumitsu

    2004-01-01

    Crystal structure of deuterated glycinium phosphite was studied in the paraelectric (P) phase at 348 K and in the ferroelectric (F) phase at 223 K by means of the single crystal neutron diffraction. Deuteration rate is estimated to be 0.939 by the least-squares refinement. In the P phase, quasi-one-dimensional hydrogen bond chains are built by mutually linking the DPO 3 2- anions through two different types of hydrogen bonds with the bond angles of 179.2 and 171.6deg. Two independent deuterons within the hydrogen bonds forming the chains are disordered over two sites separated by 0.545 and 0.539A. In the F phase, they order at a position nearly equal to one of two sites related by the disorder in the P phase. With the ordering of the deuterons, the P-O bonds with covalently bonded deuteron elongate, and those without covalently bonded deuteron reduce their lengths to some extend from the values determined in the P phase. Two oxygens involved in the hydrogen bond with the bond angle 179.2deg exhibits especially large displacements in the F phase. This suggests strongly an importance of this hydrogen bond in the polarization appearance and in the ferroelectric transition. Comparison with results of non-deuterated salt indicates that only the hydrogen bonds forming the chains show significant isotope shift. In particular, the hydrogen bond with the bond angle 179.2deg exhibits the most pronounced shift on the angle parameter defined by the angle between the line connecting two sites of disordered proton or deuteron and the line connecting two oxygens involved in the hydrogen bond. (author)

  6. Structural matching of ferroelectric domains and associated distortion in potassium titanyl phosphate crystals

    CERN Document Server

    Pernot-Rejmankova, P; Cloetens, P; Lyford, T; Baruchel, J

    2003-01-01

    The surface deformation and atomic-level distortions associated with crystal structural matching at ferroelectric inversion domain walls are investigated in periodically poled potassium titanyl phosphate (KTP) crystals. A deformation, of the order of 10 sup - sup 8 m in scale and having the periodicity of the domains, is observed at the surfaces by optical interferometry. It is discussed in terms of the piezoelectric effect. The matching of the crystal structures at the domain walls is studied by combining the hard x-ray Fresnel phase-imaging technique with Bragg diffraction imaging methods ('Bragg-Fresnel imaging') and using synchrotron radiation. Quantitative analysis of the contrast of the Bragg-Fresnel images recorded as a function of the propagation distance is demonstrated to allow the determination of how the domains are matched at the atomic (unit cell) level, even though the spatial resolution of the images is on the scale of micrometres. The atom P(1) is determined as the linking atom for connecting...

  7. Iron site location in Fe-diffused lithium niobate crystals by combined RBS-PIXE-NRA analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zaltron, A. [University of Padova and CNISM, Via Marzolo 8, 35131 Padova (Italy); Argiolas, N., E-mail: nicola.argiolas@unipd.it [University of Padova and CNISM, Via Marzolo 8, 35131 Padova (Italy); Laboratori Nazionali di Legnaro, Istituto Nazionale Fisica Nucleare, Viale dell' Universita 2, 35020 Legnaro (Padova) (Italy); De Salvador, D.; Bazzan, M. [University of Padova and CNISM, Via Marzolo 8, 35131 Padova (Italy); Laboratori Nazionali di Legnaro, Istituto Nazionale Fisica Nucleare, Viale dell' Universita 2, 35020 Legnaro (Padova) (Italy); Ciampolillo, M.V.; Bacci, L.; Sada, C. [University of Padova and CNISM, Via Marzolo 8, 35131 Padova (Italy)

    2012-03-15

    Iron diffused x-cut lithium niobate samples have been studied from a structural point of view by ion beam analysis techniques in channeling conditions. The aim of this work is to determine the most probable position of iron atoms after high temperature diffusion treatment in pure oxygen atmosphere and to verify their location after an additional full reducing annealing at low temperature. The results are compared with the bulk doping case that can be considered the final equilibrium state of the diffusion process. By comparing the iron signal with niobium and lithium counterparts in angular scans along proper crystallographic directions, we demonstrate that iron occupies in any case the lithium site or a very close position regardless of the reduction degree, just as in the case of bulk doped samples.

  8. Macroscopic polarization and thermoluminescence of barium niobate - sodium niobate

    International Nuclear Information System (INIS)

    Gorban', I.S.; Gumenyuk, A.F.; Omel'yanenko, V.A.

    1989-01-01

    Thermoluminescence (TL) of initial and thermally treated purposely undoped crystals of barium niobate - sodium has been studied within 85-400 K. The TL intensity is found to depend on the temperature to which the sample has been heated. A conclusion is drawn that nonstationarity of the TL properties is due to slowly occuring processes of compensation of pyrocharge, which depend on the temperatural prehistory of the sample. A mechanism of the traps transformation in a strong pyrofield of high-impedance crystals is discussed

  9. Submicrosecond electro-optic switching in the liquid-crystal smectic A phase: The soft-mode ferroelectric effect

    Science.gov (United States)

    Andersson, G.; Dahl, I.; Keller, P.; Kuczyński, W.; Lagerwall, S. T.; Skarp, K.; Stebler, B.

    1987-08-01

    A new liquid-crystal electro-optic modulating device similar to the surface-stabilized ferroelectric liquid-crystal device is described. It uses the same kind of ferroelectric chiral smectics and the same geometry as that device (thin sample in the ``bookshelf '' layer arrangement) but instead of using a tilted smectic phase like the C* phase, it utilizes the above-lying, nonferroelectric A phase, taking advantage of the electroclinic effect. The achievable optical intensity modulation that can be detected through the full range of the A phase is considerably lower than for the surface-stabilized device, but the response is much faster. Furthermore, the response is strictly linear with respect to the applied electric field. The device concept is thus appropriate for modulator rather than for display applications. We describe the underlying physics and present measurements of induced tilt angle, of light modulation depth, and of rise time.

  10. The influence of the coexistence of ferroelectric and antiferroelectric states on the lead lanthanum zirconate titanate crystal structure

    International Nuclear Information System (INIS)

    Ishchuk, V M; Baumer, V N; Sobolev, V L

    2005-01-01

    We present results of detailed investigation of the crystal structure of Pb 1-3x/2 La x (Zr 1-y Ti y )O 3 solid solutions. In this letter our attention is concentrated on the series of solid solutions with x = 6% usually referred to as relaxor ferroelectrics. We have established the reasons for the non-cubic crystal structure of these solid solutions at the temperatures below T C . It is demonstrated that the peculiarities of the properties of Pb 1-3x/2 La x (Zr 1-y Ti y )O 3 depend on the position of a particular solid solution with respect to the hysteresis ferroelectric-antiferroelectric region in the 'Ti-content-temperature' phase diagram. (letter to the editor)

  11. Electro-optic switching and dielectric spectroscopy studies of ferroelectric liquid crystals with low and high spontaneous polarization

    Czech Academy of Sciences Publication Activity Database

    Malik, P.; Raina, K.K.; Bubnov, Alexej; Choudhary, A.; Singh, R.

    Roč. 519, č. 3 ( 2010 ), 1052-1055 ISSN 0040-6090 R&D Projects: GA AV ČR IAA100100911; GA AV ČR(CZ) GA202/09/0047 Grant - others:RFASI(RU) 02.740.11.5166 Institutional research plan: CEZ:AV0Z10100520 Keywords : spontaneous polarization * ferroelectric liquid crystal * relaxation frequency * Goldstone mode Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.909, year: 2010

  12. Advantages and Challenges of Relaxor-PbTiO3 Ferroelectric Crystals for Electroacoustic Transducers- A Review

    Science.gov (United States)

    Zhang, Shujun; Li, Fei; Jiang, Xiaoning; Kim, Jinwook; Luo, Jun; Geng, Xuecang

    2014-01-01

    Relaxor-PbTiO3 (PT) based ferroelectric crystals with the perovskite structure have been investigated over the last few decades due to their ultrahigh piezoelectric coefficients (d33 > 1500 pC/N) and electromechanical coupling factors (k33 > 90%), far outperforming state-of-the-art ferroelectric polycrystalline Pb(Zr,Ti)O3 ceramics, and are at the forefront of advanced electroacoustic applications. In this review, the performance merits of relaxor-PT crystals in various electroacoustic devices are presented from a piezoelectric material viewpoint. Opportunities come from not only the ultrahigh properties, specifically coupling and piezoelectric coefficients, but through novel vibration modes and crystallographic/domain engineering. Figure of merits (FOMs) of crystals with various compositions and phases were established for various applications, including medical ultrasonic transducers, underwater transducers, acoustic sensors and tweezers. For each device application, recent developments in relaxor-PT ferroelectric crystals were surveyed and compared with state-of-the-art polycrystalline piezoelectrics, with an emphasis on their strong anisotropic features and crystallographic uniqueness, including engineered domain - property relationships. This review starts with an introduction on electroacoustic transducers and the history of piezoelectric materials. The development of the high performance relaxor-PT single crystals, with a focus on their uniqueness in transducer applications, is then discussed. In the third part, various FOMs of piezoelectric materials for a wide range of ultrasound applications, including diagnostic ultrasound, therapeutic ultrasound, underwater acoustic and passive sensors, tactile sensors and acoustic tweezers, are evaluated to provide a thorough understanding of the materials’ behavior under operational conditions. Structure-property-performance relationships are then established. Finally, the impacts and challenges of relaxor

  13. Lattice dynamics and central-mode phenomena in the dielectric response of ferroelectrics and related materials

    Czech Academy of Sciences Publication Activity Database

    Buixaderas, Elena; Kamba, Stanislav; Petzelt, Jan

    2004-01-01

    Roč. 308, - (2004), s. 131-192 ISSN 0015-0193 R&D Projects: GA ČR GA202/01/0612; GA AV ČR IAA1010213; GA MŠk OC 525.20 Institutional research plan: CEZ:AV0Z1010914 Keywords : phonons in crystal lattice * commensurate-incommensurate transitions * dielectric properties of solids and liquids * ferroelectricity and antiferroelectricity * niobates * tantantalates * PZT ceramics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.517, year: 2004

  14. Relaxor-based ferroelectric single crystals: growth, domain engineering, characterization and applications

    Science.gov (United States)

    Sun, Enwei; Cao, Wenwu

    2014-01-01

    In the past decade, domain engineered relaxor-PT ferroelectric single crystals, including (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT), (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT) and (1-x-y)Pb(In1/2Nb1/2)O3-yPb(Mg1/3Nb2/3)O3-xPbTiO3 (PIN-PMN-PT), with compositions near the morphotropic phase boundary (MPB) have triggered a revolution in electromechanical devices owing to their giant piezoelectric properties and ultra-high electromechanical coupling factors. Compared to traditional PbZr1-xTixO3 (PZT) ceramics, the piezoelectric coefficient d33 is increased by a factor of 5 and the electromechanical coupling factor k33 is increased from 90%. Many emerging rich physical phenomena, such as charged domain walls, multi-phase coexistence, domain pattern symmetries, etc., have posed challenging fundamental questions for scientists. The superior electromechanical properties of these domain engineered single crystals have prompted the design of a new generation electromechanical devices, including sensors, transducers, actuators and other electromechanical devices, with greatly improved performance. It took less than 7 years from the discovery of larger size PMN-PT single crystals to the commercial production of the high-end ultrasonic imaging probe “PureWave”. The speed of development is unprecedented, and the research collaboration between academia and industrial engineers on this topic is truly intriguing. It is also exciting to see that these relaxor-PT single crystals are being used to replace traditional PZT piezoceramics in many new fields outside of medical imaging. The new ternary PIN-PMN-PT single crystals, particularly the ones with Mn-doping, have laid a solid foundation for innovations in high power acoustic projectors and ultrasonic motors, hinting another revolution in underwater SONARs and miniature actuation devices. This article intends to provide a comprehensive review on the development of relaxor-PT single crystals, spanning material discovery, crystal growth

  15. Growth of large size lithium niobate single crystals of high quality by tilting-mirror-type floating zone method

    Energy Technology Data Exchange (ETDEWEB)

    Sarker, Abdur Razzaque, E-mail: razzaque_ru2000@yahoo.com [Department of Physics, University of Rajshahi (Bangladesh)

    2016-05-15

    Large size high quality LiNbO{sub 3} single crystals were grown successfully by tilting-mirror-type floating zone (TMFZ) technique. The grown crystals were characterized by X-ray diffraction, etch pits density measurement, Impedance analysis, Vibrating sample magnetometry (VSM) and UV-Visible spectrometry. The effect of mirror tilting during growth on the structural, electrical, optical properties and defect density of the LiNbO{sub 3} crystals were investigated. It was found that the defect density in the crystals reduced for tilting the mirror in the TMFZ method. The chemical analysis revealed that the grown crystals were of high quality with uniform composition. The single crystals grown by TMFZ method contains no low-angle grain boundaries, indicating that they can be used for high efficiency optoelectronic devices. (author)

  16. Silver niobates

    International Nuclear Information System (INIS)

    Tanirbergenov, B.; Rozhenko, S.P.

    1979-01-01

    By means of determination of residual concentrations and pH measurements investigated are the AgNO 3 -KNbO 3 -H 2 O, AgNO 3 -K 3 NbO 4 -H 2 O, AgNO 3 -K 8 Nb 16 O 19 -H 2 O systems and established is formation of meta-, ortho-and hexaniobates of silver. AgNbO 3 x H 2 O, Ag 8 Nb 6 O 19 x 6H 2 O and Ag 3 NbO 3 x 2.5H 2 O are separated from aqueous solution. Using the methods of differential-thermal, thermogravimetric and X-ray-phase analyses it is shown that silver metaniobate transforms into the crystal state at 530 deg C. Ortho- and hexaniobate of silver decompose at 500 deg C with formation of silver metaniobate and metal silver

  17. Material modifications in lithium niobate and lithium tantalate crystals by ion irradiation; Materialmodifikationen in Lithiumniobat- und Lithiumtantalat-Kristallen durch Ionenbestrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Raeth, Niels Lennart

    2017-02-17

    The artificially produced crystals lithium niobate (LiNbO{sub 3}) and the closely related lithium tantalate (LiTaO{sub 3}) are proven starting materials for producing active and passive devices that can guide, amplify, switch and process light. For this purpose, it is often necessary to be able to influence the refractive index of the substrate targeted, which is possible in addition to other methods by irradiation of the materials with fast light ions. In this work, lithium niobate and lithium tantalate crystals are irradiated with alpha particles, {sup 3}He ions, deuterons, and protons at projectile energies of up to 14 MeV / nucleon. Energy and crystal thickness are chosen so that the projectiles penetrate the entire sample and are not implanted. All isotopes responsible for the unwanted nuclear activation of the crystals due to the irradiation are relatively short-lived and overall the activation decreases fast enough to allow the safe handling of the irradiated samples after a storage period of a few days to a few weeks. The refractive index changes produced in lithium niobate and lithium tantalate by irradiation with the different projectiles are determined interferometrically and can also be measured by suitable choice of the sample geometry as a function of the ion penetration depth: In LiNbO{sub 3} the ordinary refractive index decreases, the extraordinary increases equally. In LiTaO{sub 3}, both the ordinary and the extraordinary refractive indices decrease as a result of the irradiation; the ordinary refractive index change is many times stronger than the extraordinary one. There is an enormous long-term stability at room temperature for both crystal systems: Even after eleven (LiNbO{sub 3}) or three (LiTaO{sub 3}) years, no decrease in the ion beam-induced refractive index change can be observed. The ion beam-induced refractive index changes are probably the result of atomic displacements such as vacancies, defect clusters or ''latent tracks

  18. Holographic recording in a doubly doped lithium niobate crystal with two wavelengths: a blue laser diode and a green laser

    Science.gov (United States)

    Komori, Yuichi; Ishii, Yukihiro

    2010-08-01

    A doubly-doped LiNbO3 (LN) crystal has been well used as a nonvolatile two-wavelength recording material. By using two levels of the crystal, two-kind holograms can be recorded on one crystal; a hologram is recorded with a 405-nm blue laser diode (LD) for a deep Mn level, and another hologram is with a 532-nm green laser for a shallow Fe level. The recording capacity doubles. A 780-nm LD is non-volatile reconstructing source since the LD line is insensitive to both levels. Multiplexed reconstructed images are demonstrated by using a sharp angular selectivity of a volume LN crystal keeping Bragg condition with spherical reconstructions.

  19. Ferroelectric crystals for photonic applications including nanoscale fabrication and characterization techniques

    CERN Document Server

    Ferraro, Pietro; De Natale, Paolo

    2015-01-01

    This book details the latest achievements in ferroelectric domain engineering and characterization at micro- and nano-scale dimensions and periods. It combines basic research of magnetic materials with device and production orientation.

  20. Effect of alkyl chains length on properties of ferroelectric liquid crystals with the keto group attached to the molecule core

    Czech Academy of Sciences Publication Activity Database

    Bubnov, Alexej; Novotná, Vladimíra; Pociecha, D.; Hamplová, Věra; Kašpar, Miroslav

    2012-01-01

    Roč. 85, č. 10 (2012), s. 849-860 ISSN 0141-1594 R&D Projects: GA ČR(CZ) GAP204/11/0723 Grant - others:AV ČR(CZ) M100101211; AV ČR(CZ) M100101204 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectric liquid crystal * keto group * lactic acid derivative * spontaneous quantities * SAXS * helix pitch Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.863, year: 2012 http://www.tandf.co.uk/journals/titles/01411594.asp

  1. Lithium niobate packaging challenges

    International Nuclear Information System (INIS)

    Murphy, E.J.; Holmes, R.J.; Jander, R.B.; Schelling, A.W.

    1988-01-01

    The use of lithium niobate integrated optic devices outside of the research laboratory is predicated on the development of a sound packaging method. The authors present a discussion of the many issues that face the development of a viable, robust packaging technology. The authors emphasize the interaction of lithium niobate's physical properties with available packaging materials and technologies. The broad range of properties (i.e. electro-optic, piezo-electric, pyro-electric, photorefractive...) that make lithium niobate an interesting material in many device applications also make it a packaging challenge. The package design, materials and packaging technologies must isolate the device from the environment so that lithium niobate's properties do not adversely affect the device performance

  2. Molecular ferroelectrics: where electronics meet biology.

    Science.gov (United States)

    Li, Jiangyu; Liu, Yuanming; Zhang, Yanhang; Cai, Hong-Ling; Xiong, Ren-Gen

    2013-12-28

    In the last several years, we have witnessed significant advances in molecular ferroelectrics, with the ferroelectric properties of molecular crystals approaching those of barium titanate. In addition, ferroelectricity has been observed in biological systems, filling an important missing link in bioelectric phenomena. In this perspective, we will present short historical notes on ferroelectrics, followed by an overview of the fundamentals of ferroelectricity. The latest developments in molecular ferroelectrics and biological ferroelectricity will then be highlighted, and their implications and potential applications will be discussed. We close by noting molecular ferroelectric as an exciting frontier between electronics and biology, and a number of challenges ahead are also described.

  3. Effect of the structure and mechanical properties of the near-surface layer of lithium niobate single crystals on the manufacture of integrated optic circuits

    Science.gov (United States)

    Sosunov, A. V.; Ponomarev, R. S.; Yur'ev, V. A.; Volyntsev, A. B.

    2017-01-01

    This paper shows that the near-surface layer of a lithium niobate single layer 15 μm in depth is essentially different from the rest of the volume of the material from the standpoint of composition, structure, and mechanical properties. The pointed out differences are due to the effect of cutting, polishing, and smoothing of the lithium niobate plates, which increase the density of point defects and dislocations. The increasing density of the structural defects leads to uncontrollable changes in the conditions of the formations of waveguides and the drifting of characteristics of integrated optical circuits. The results obtained are very important for the manufacture of lithium niobate based integrated optical circuits.

  4. Evolution of defect signatures at ferroelectric domain walls in Mg-doped LiNbO3

    International Nuclear Information System (INIS)

    Nataf, Guillaume F.; Guennou, Mael; Haussmann, Alexander; Barrett, Nick; Kreisel, Jens

    2016-01-01

    The domain structure of uniaxial ferroelectric lithium niobate single crystals is investigated using Raman spectroscopy mapping. The influence of doping with magnesium and poling at room temperature is studied by analysing frequency shifts at domain walls and their variations with dopant concentration and annealing conditions. It is shown that defects are stabilized at domain walls and that changes in the defect structures with Mg concentration can be probed by the shift of Raman modes. We show that the signatures of polar defects in the bulk and at the domain walls differ. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Evolution of defect signatures at ferroelectric domain walls in Mg-doped LiNbO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Nataf, Guillaume F. [Materials, Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, 4422, Belvaux (Luxembourg); Service de Physique de l' Etat Condense, DSM/IRAMIS/SPEC, CNRS UMR 3680, CEA Saclay, 91191, Gif sur Yvette cedex (France); Guennou, Mael [Materials, Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, 4422, Belvaux (Luxembourg); Haussmann, Alexander [Institut fuer Angewandte Photophysik, Technische Universitaet Dresden, George-Baehr-Str. 1, 01069, Dresden (Germany); Barrett, Nick [Service de Physique de l' Etat Condense, DSM/IRAMIS/SPEC, CNRS UMR 3680, CEA Saclay, 91191, Gif sur Yvette cedex (France); Kreisel, Jens [Materials, Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, 4422, Belvaux (Luxembourg); Physics and Materials Science Research Unit, University of Luxembourg, 41 Rue du Brill, 4422, Belvaux (Luxembourg)

    2016-03-15

    The domain structure of uniaxial ferroelectric lithium niobate single crystals is investigated using Raman spectroscopy mapping. The influence of doping with magnesium and poling at room temperature is studied by analysing frequency shifts at domain walls and their variations with dopant concentration and annealing conditions. It is shown that defects are stabilized at domain walls and that changes in the defect structures with Mg concentration can be probed by the shift of Raman modes. We show that the signatures of polar defects in the bulk and at the domain walls differ. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Two-dimensional ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Blinov, L M; Fridkin, Vladimir M; Palto, Sergei P [A.V. Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow, Russian Federaion (Russian Federation); Bune, A V; Dowben, P A; Ducharme, Stephen [Department of Physics and Astronomy, Behlen Laboratory of Physics, Center for Materials Research and Analysis, University of Nebraska-Linkoln, Linkoln, NE (United States)

    2000-03-31

    The investigation of the finite-size effect in ferroelectric crystals and films has been limited by the experimental conditions. The smallest demonstrated ferroelectric crystals had a diameter of {approx}200 A and the thinnest ferroelectric films were {approx}200 A thick, macroscopic sizes on an atomic scale. Langmuir-Blodgett deposition of films one monolayer at a time has produced high quality ferroelectric films as thin as 10 A, made from polyvinylidene fluoride and its copolymers. These ultrathin films permitted the ultimate investigation of finite-size effects on the atomic thickness scale. Langmuir-Blodgett films also revealed the fundamental two-dimensional character of ferroelectricity in these materials by demonstrating that there is no so-called critical thickness; films as thin as two monolayers (1 nm) are ferroelectric, with a transition temperature near that of the bulk material. The films exhibit all the main properties of ferroelectricity with a first-order ferroelectric-paraelectric phase transition: polarization hysteresis (switching); the jump in spontaneous polarization at the phase transition temperature; thermal hysteresis in the polarization; the increase in the transition temperature with applied field; double hysteresis above the phase transition temperature; and the existence of the ferroelectric critical point. The films also exhibit a new phase transition associated with the two-dimensional layers. (reviews of topical problems)

  7. Transmission electron microscope studies of phase transitions in single crystals and ceramics of ferroelectric Pb(Sc1/2Ta1/2)O3

    International Nuclear Information System (INIS)

    Baba-Kishi, K.Z.; Barber, D.J.

    1990-01-01

    An account is given of transmission electron microscope investigations of the phase transitions in single crystals and ceramics of the complex perovskite-structured ferroelectric 'relaxor' compound Pb(Sc 1/2 Ta 1/2 )O 3 . The crystal symmetries pertaining to both the non-polar paraelectric (PE) and polar ferroelectric (FE) states have been studied by the technique of convergent-beam electron diffraction. A new phase transition has been discovered in the temperature range for which the FE and PE states coexist. The new phase transition is interpreted as the creation of a modulated antiferroelectric state, and this is viewed as marking a departure from relaxor behaviour towards more 'normal' ferroelectric behaviour. (orig.)

  8. Piezo-optical and electro-optical behaviour of nematic liquid crystals dispersed in a ferroelectric copolymer matrix

    International Nuclear Information System (INIS)

    Ganesan, Lakshmi Meena; Wirges, Werner; Gerhard, Reimund; Mellinger, Axel

    2010-01-01

    Polymer-dispersed liquid crystals (PDLCs) are composite materials that consist of micrometre-sized liquid-crystal (LC) droplets embedded in a polymer matrix. From ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) and a nematic LC, PDLC films containing 10 and 60 wt% LC were prepared, and their electro-optical and piezo-optical behaviour was investigated. The electric field that is generated by the application of mechanical stress leads to changes in the transmittance of the PDLC film through a combination of piezoelectric and electro-optical effects. Such a piezo-optical PDLC material may be useful, e.g., in sensing and visualization applications.

  9. Elastic (stress-strain) halo associated with ion-induced nano-tracks in lithium niobate: role of crystal anisotropy

    International Nuclear Information System (INIS)

    Rivera, A; Garcia, G; Olivares, J; Crespillo, M L; Agulló-López, F

    2011-01-01

    The elastic strain/stress fields (halo) around a compressed amorphous nano-track (core) caused by a single high-energy ion impact on LiNbO 3 are calculated. A method is developed to approximately account for the effects of crystal anisotropy of LiNbO 3 (symmetry 3m) on the stress fields for tracks oriented along the crystal axes (X, Y or Z). It only considers the zero-order (axial) harmonic contribution to the displacement field in the perpendicular plane and uses effective Poisson moduli for each particular orientation. The anisotropy is relatively small; however, it accounts for some differential features obtained for irradiations along the crystallographic axes X, Y and Z. In particular, the irradiation-induced disorder (including halo) and the associated surface swelling appear to be higher for irradiations along the X- or Y-axis in comparison with those along the Z-axis. Other irradiation effects can be explained by the model, e.g. fracture patterns or the morphology of pores after chemical etching of tracks. Moreover, it offers interesting predictions on the effect of irradiation on lattice parameters.

  10. Propagation characteristics of a focused laser beam in a strontium barium niobate photorefractive crystal under reverse external electric field.

    Science.gov (United States)

    Guo, Q L; Liang, B L; Wang, Y; Deng, G Y; Jiang, Y H; Zhang, S H; Fu, G S; Simmonds, P J

    2014-10-01

    The propagation characteristics of a focused laser beam in a SBN:75 photorefractive crystal strongly depend on the signal-to-background intensity ratio (R=Is/Ib) under reverse external electric field. In the range 20>R>0.05, the laser beam shows enhanced self-defocusing behavior with increasing external electric field, while it shows self-focusing in the range 0.03>R>0.01. Spatial solitons are observed under a suitable reverse external electric field for R=0.025. A theoretical model is proposed to explain the experimental observations, which suggest a new type of soliton formation due to "enhancement" not "screening" of the external electrical field.

  11. Ferroelectric domain structures in -oriented K0.15Na0.85NbO3 lead-free single crystal

    Directory of Open Access Journals (Sweden)

    Yan Chen

    2015-03-01

    Full Text Available In this work, ferroelectric domain structures of -oriented K0.15Na0.85NbO3 single crystal are characterized. Transmission electron microscopy (TEM observation revealed high-density of laminate domain structures in the crystal and the lattices of the neighboring domains are found to be twisted in a small angle. Superlattice diffraction spots of 1 2 { eeo } and 1 2 { ooe } in electron diffraction patterns are observed in the crystal, revealing the a+a+c− tilting of oxygen octahedral in the perovskite structure. The piezoresponse of domains and in-situ poling responses of K0.15Na0.85NbO3 crystal are observed by piezoresponse force microscopy (PFM, and the results assure its good ferroelectric properties.

  12. Emergent Low-Symmetry Phases and Large Property Enhancements in Ferroelectric KNbO 3 Bulk Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lummen, Tom T. A. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 USA; Leung, J. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 USA; Kumar, Amit [School of Mathematics and Physics, Queen' s University Belfast, University Road, Belfast BT71NN Northern Ireland UK; Wu, X. [Department of Physics, University of Texas at Austin, Austin TX 78712 USA; Ren, Y. [Department of Physics, University of Texas at Austin, Austin TX 78712 USA; VanLeeuwen, Brian K. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 USA; Haislmaier, Ryan C. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 USA; Holt, Martin [Center for Nanoscale Materials, Argonne National Laboratory, Argonne IL 60439 USA; Lai, Keji [Department of Physics, University of Texas at Austin, Austin TX 78712 USA; Kalinin, Sergei V. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Gopalan, Venkatraman [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 USA

    2017-06-19

    The design of new or enhanced functionality in materials is traditionally viewed as requiring the discovery of new chemical compositions through synthesis. Large property enhancements may however also be hidden within already well-known materials, when their structural symmetry is deviated from equilibrium through a small local strain or field. Here, the discovery of enhanced material properties associated with a new metastable phase of monoclinic symmetry within bulk KNbO3 is reported. This phase is found to coexist with the nominal orthorhombic phase at room temperature, and is both induced by and stabilized with local strains generated by a network of ferroelectric domain walls. While the local microstructural shear strain involved is only approximate to 0.017%, the concurrent symmetry reduction results in an optical second harmonic generation response that is over 550% higher at room temperature. Moreover, the meandering walls of the low-symmetry domains also exhibit enhanced electrical conductivity on the order of 1 S m(-1). This discovery reveals a potential new route to local engineering of significant property enhancements and conductivity through symmetry lowering in ferroelectric crystals.

  13. Investigation of Ferroelectric Domain Walls by Raman Spectroscopy

    Science.gov (United States)

    Stone, Gregory A.

    Ferroelectric materials are characterized by an intrinsic spontaneous electric dipole moment that can be manipulated by the application of an electric field. Regions inside the crystal, known as domains, can have the spontaneous dipole moments oriented in a different direction than the surrounding crystal. Due to favorable piezoelectric, pyroelectric, electro-optic, and nonlinear optical properties, ferroelectric materials are attractive for commercial applications. Many devices, such as nonlinear frequency converters, require precisely engineered domain patterns. The properties of domains and their boundaries, known as domain walls, are vital to the performance and limitations of these devices. As a result, ferroelectric domains and the domain walls have been the focus of many scientific studies. Despite all this work, questions remain regarding their properties. This work is aimed at developing a better understanding of the properties of the domain wall using confocal Raman spectroscopy. Raman spectra taken from domain walls in Lithium Niobate and Lithium Tantalate reveal two distinct changes in the Raman spectra: (1) Shifts in frequency of the bulk Raman modes, which persists over a range of 0.2-0.5 mu m from the domain wall. The absence of this effect in defect free stoichiometric Lithium Tantalate indicates that the shifts are related to defects inside the crystal. (2) The presence of Raman modes corresponding to phonons propagating orthogonal to the laser beam axis, which are not collected in the bulk crystal. The phonons also preferential propagate normal to the domain wall. These modes are detected up to 0.35 mum from the domain wall. The observation and separation of these effects was made possible by the optimized spatial resolution (0.23 mum) of a home-built scanning confocal microscope and the fact that degeneracy of the transverse and longitudinal phonon polarization is lifted by polar phonons in Lithium Niobate and Lithium Tantalate. Raman

  14. Ferroelectric crystals for photonic applications including nanoscale fabrication and characterization techniques

    CERN Document Server

    Grilli, Simonetta

    2008-01-01

    This book deals with the latest achievements in the field of ferroelectric domain engineering and characterization at micron- and nano-scale dimensions and periods. The book collects the results obtained in the last years by world scientific leaders in the field, thus providing a valid and unique overview of the state of the art and also a view to future applications of those engineered materials in the field of photonics.

  15. Ferroelectric domain pattern in barium titanate single crystals studied by means of digital holographic microscopy

    Czech Academy of Sciences Publication Activity Database

    Mokrý, Pavel; Psota, Pavel; Steiger, Kateřina; Václavík, Jan; Doleček, Roman; Vápenka, David; Lédl, Vít

    2016-01-01

    Roč. 49, č. 25 (2016), č. článku 255307. ISSN 0022-3727 R&D Projects: GA ČR(CZ) GA14-32228S Institutional support: RVO:61389021 Keywords : ferroelectric domain patterns * electro-optical materials * digital holographic microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.588, year: 2016 http://iopscience.iop.org/article/10.1088/0022-3727/49/25/255307

  16. Influence of Bias on the Friction Imaging of Ferroelectric Domains in Single Crystal Barium Titanate Energy Storage Materials

    Directory of Open Access Journals (Sweden)

    Lan Chen

    2014-01-01

    Full Text Available The friction imaging of newlycleaved surface domains of single crystal BaTiO3 energy storage materials under both positive and negative voltage bias is investigated by scanning force microscope. When the bias was applied and reversed, three regions with different brightness and contrast in friction image indicated different response to the biases: the friction image of domain A displayed a great change in brightness while domains B and C displayed only a very small change. Possible mechanisms of the interesting phenomena originating from different static force between different charged tip and the periodical array of surface charges inside the inplane domains were proposed. These results provide a new method for the determination of the polarization direction for the domain parallel to the surface and may be useful in the investigation of ferroelectric energy storage materials, especially the relationship between the polarization direction of domain and the bias.

  17. Raman effect in ferroelectric Cd2Nb2O7 and in other crystals with pyrochlorine-type structure

    International Nuclear Information System (INIS)

    Pisarev, R.V.; Sinij, I.G.; Kuz'minov, E.G.; Myl'nikova, I.E.

    1976-01-01

    Vibrational structure of cadmium and lead pyroniobates and a number of other crystals with a pyrochlore structure has been investigated by Raman scattering. The scattering has been studied using a double monochromator, HeNe laser, and a photons counter. In the Raman spectrum of cadmium and lead pyroniobates three frequency band1 can be distinguished. In the spectrum of rhombohedral lead pyroniobate the band structure in resolved much better than in the spectrum of cubic cadmium pyroniobate. The spectrum of lead pyroniobate crystals doped with magnesium and zinc ions has a medium (in the sense of complexity) structure, because big lead ions deteriorate the pyrochlore structure but doping of lead pyroniobate with Mg 2+ and Zn 2+ ions improves it. More than six bands in the Raman spectrum is associated with the presence of impurities in cubic cadmium pyroniobate that deteriorate its cubic structure. The decrease of temperature leads to a big change of the Cd 2 Nb 2 O 7 spectrum. However, the spectrum of Pb 2 Nb 2 O 7 -Zn cubic crystal measured ar temperatures below 100 deg K remais unchanged. The chages of the Cd 2 Nb 2 O 7 spectrum are associated with phase transitions at 200 and 85 K and also with ferroelectric transition at 185 K

  18. Micro- and nanostructuration of lithium niobate

    International Nuclear Information System (INIS)

    Hartung, Holger

    2010-01-01

    In the framework of this thesis the application of the ion-beam-enhanced-etching (IBEE) technique for the fabrication of different optical elements, among these photonic crystals, in lithium niobate, was studied. The development of a mask technology fitted to the requirements of the IBEE technique as well as a simulation of the process were performed. Hereby the limitations of the technique in view on minimal structure sizes and structure quality were analyzed. In chapter 1 first the material lithium niobate with its properties and the structuration procedures studied hitherto in the literature is presented. Chapter 2 presents the functionality of the IBEE process and describes the studies on the application of IBEE in lithium niobate performed in the framework of this thesis. In chapter 3 the experimental conditions of all applied processes of the IBEE procedure, the processes used for the mask fabrication, as well all further applied methods and technologies are summarized. Chapter 4 deals with the mask fabrication. The requirements on the masks and the developments necessary for their fulfilment are studied. In chapter 5 the performed simulation of the irradiation, annealing, and etching process is described. This simulation makes the prediciton of the geometry of the components from the process parameters and vice versa the determination of parameters for the reaching of an optimal element geometry possible. In chapter 6 the application of the technique for the fabrication of photonic-crystal membranes and their optical characterization is described. Chapter 7 shows the fabrication of different waveguide and diffractive elements in lithium niobate by means of IBEE.

  19. Photovoltaic effect and photopolarization in Pb [(Mg1/3Nb2/3) 0.68Ti0.32] O3 crystal

    Science.gov (United States)

    Makhort, A. S.; Chevrier, F.; Kundys, D.; Doudin, B.; Kundys, B.

    2018-01-01

    Ferroelectric materials are an alternative to semiconductor-based photovoltaics and offer the advantage of above bandgap photovoltage generation. However, there are few known compounds, and photovoltaic efficiencies remain low. Here, we report the discovery of a photovoltaic effect in undoped lead magnesium niobate-lead titanate crystal and a significant improvement in the photovoltaic response under suitable electric fields and temperatures. The photovoltaic effect is maximum near the electric-field-driven ferroelectric dipole reorientation, and increases threefold near the Curie temperature (Tc). Moreover, at ferroelectric saturation, the photovoltaic response exhibits clear remanent and transient effects. The transient-remanent combinations together with electric and thermal tuning possibilities indicate photoferroelectric crystals as emerging elements for photovoltaics and optoelectronics, relevant to all-optical information storage and beyond.

  20. Optimized Pyroelectric Vidicon Thermal Imager. Volume II. Improper Ferroelectric Crystal Growth.

    Science.gov (United States)

    1980-09-01

    4.2.1 Apparatus .......................... 77 4.2.2 Growth from Acidic Media .................o 78 4.2.3 Hydrothermal Growth in Basic Media ...... 99...method of hydrothermal growth was examined using both acidic and basic solvents. (1) Standard Composition Our standard composition was derived from... Acid 10 Good, well formed crystals. Acrylic Acid 10 Very good, clear crystals. Glycine 10 Poor crystals. Oxalic Acid 10 Precipitation of calcium and

  1. Relaxor ferroelectricity, ferromagnetic and optical second harmonic properties in lanthanum lithium niobate (La{sub 0.05}Li{sub 0.85}NbO{sub 3}) nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Díaz-Moreno, Carlos A., E-mail: cdiazmoreno@utep.edu [Department of Physics of University of Texas at El Paso, 500 W. University Ave, El Paso, TX 79968 (United States); Ding, Yu; Li, Chunqiang [Department of Physics of University of Texas at El Paso, 500 W. University Ave, El Paso, TX 79968 (United States); Portelles, Jorge [Facultad de Física, Universidad de La Habana, San lázaro y L, 10400 (Cuba); Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología, km 107 Carretera Tijuana-Ensenada, Ensenada, B.C. 22860 (Mexico); Heiras, J. [Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología, km 107 Carretera Tijuana-Ensenada, Ensenada, B.C. 22860 (Mexico); Hurtado-Macias, A. [Centro de Investigación en Materiales Avanzados S.C., Miguel de Cervantes #120, Complejo Industrial Chihuahua, Chihuahua, C.P. 31109 (Mexico); Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 (United States); Farias, J.R. [Instituto de Ingeniería y Tecnología, UACJ, Avenida del Charro #450 N. Cd. Juárez, Chihuahua, C.P. 32310 (Mexico); González-Hernández, J. [Centro de Ingeniería y Desarrollo Industrial, Santiago de Querétaro 76130, Qro (Mexico); Yacamán, M.J. [Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 (United States); and others

    2017-07-01

    Relaxor ferroelectricity, ferromagnetism and Second Harmonic Generation properties were founded and studied as a function of a reduction heat treatment at 650 °C in a Ar-5%H{sub 2} atmosphere in stoichiometric La{sub 0.05}Li{sub 0.85}NbO{sub 3} nanoparticles of 40 nm. A diffuse dielectric anomaly related with relaxor behavior from 25 °C to 800 °C in a frequency range from 100 Hz to 1 MHz was founded. It also shows ferromagnetic anhysterestic type and ferroelectric hysteresis loops at room temperature with a magnetic spin remnant of 2.5 × 10{sup −3} emu/g and polarization saturation of 0.235 μC/cm{sup 2}, remnant polarization of 0.141 μC/cm{sup 2}, coercive field of 1.35 kV/cm, respectively. It shows very good second harmonic generation signal at 450 nm and 500 nm. High Resolution Transmission Electron Microscopy, X-ray Photoelectron Spectroscopy and Raman spectroscopy, indicate an ABO{sub 3} perovskite structure, new electronic binding energy structure for La (5s, 4d), Li (1s), Nb (4s, 3d, 4p) and oxygen (1s, 2s) and new vibrations modes on octahedron NbO{sub 6} related to multiferroic single phase nanoparticles, respectively.

  2. Nano and micro reoriented domains and their relation with the crystal structure in the new ferroelectric boracite Zn3B7O13Br

    International Nuclear Information System (INIS)

    Campa-Molina, J; Ulloa-Godinez, S; Barrera, A; Bucio, L; Mata, J

    2006-01-01

    A new zinc brome boracite Zn 3 B 7 O 13 Br has been grown by a chemical transport reaction in closed quartz ampoules at 920 K. The crystal structure was characterized by Rietveld refinement. Ferroelectric nano and micro reorientable domains were found in this material using polarizing optical microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Chemical analysis was performed with x-ray energy dispersive spectroscopy (EDX). In the crystal, a new structure transition at 586 K from orthorhombic (Pca 2 1 ) to cubic cell (F4-bar3c) has been found. This transition was corroborated by differential scanning calorimetry (DSC)

  3. Nano and micro reoriented domains and their relation with the crystal structure in the new ferroelectric boracite Zn3B7O13Br

    Science.gov (United States)

    Campa-Molina, J.; Ulloa-Godínez, S.; Barrera, A.; Bucio, L.; Mata, J.

    2006-05-01

    A new zinc brome boracite Zn3B7O13Br has been grown by a chemical transport reaction in closed quartz ampoules at 920 K. The crystal structure was characterized by Rietveld refinement. Ferroelectric nano and micro reorientable domains were found in this material using polarizing optical microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Chemical analysis was performed with x-ray energy dispersive spectroscopy (EDX). In the crystal, a new structure transition at 586 K from orthorhombic (Pca 21) to cubic cell (F\\overline 4 3c ) has been found. This transition was corroborated by differential scanning calorimetry (DSC).

  4. The effect of crystal symmetry on the maximum polarization of polycrystalline ferroelectric materials

    International Nuclear Information System (INIS)

    Jones, Jacob L.

    2010-01-01

    In polycrystalline ceramics, the degree of domain orientation in all possible crystal orientations contributes to the total realizable polarization. The extent to which domains are oriented towards an applied field can be described by a polarization distribution function. Such representations are calculated and presented in the present work for several different crystal systems including monoclinic symmetries that exhibit a polarization rotation mechanism. The relationship between the polarization distribution functions and the attainable macroscopic polarization is also developed for polycrystalline ceramics that are initially randomly oriented. In these cases, polarization rotation allows a significant degree of preferred orientation parallel to the electric field (>1000 multiples of a random distribution). However, the fraction of single crystal polarization that can be achieved (97.5%) is only marginally better than those of higher crystal symmetry.

  5. Electromechanical properties of engineered lead free potassium sodium niobate based materials =

    Science.gov (United States)

    Rafiq, Muhammad Asif

    vacancies whose concentration increases with Mn doping. Single crystals of potassium sodium niobate (KNN) were grown by a modified high temperature flux method. A boron-modified flux was used to obtain the crystals at a relatively low temperature. XRD, EDS and ICP analysis proved the chemical and crystallographic quality of the crystals. The grown KNN crystals exhibit higher dielectric permittivity (29,100) at the tetragonal-to-cubic phase transition temperature, higher remnant polarization (19.4 ?C/cm2) and piezoelectric coefficient (160 pC/N) when compared with the standard KNN ceramics. KNN single crystals domain structure was characterized for the first time by piezoforce response microscopy. It could be observed that - oriented potassium sodium niobate (KNN) single crystals reveal a long range ordered domain pattern of parallel 180° domains with zig-zag 90° domains. From the comparison of KNN Single crystals to ceramics, It is argued that the presence in KNN single crystal (and absence in KNN ceramics) of such a long range order specific domain pattern that is its fingerprint accounts for the improved properties of single crystals. These results have broad implications for the expanded use of KNN materials, by establishing a relation between the domain patterns and the dielectric and ferroelectric response of single crystals and ceramics and by indicating ways of achieving maximised properties in KNN materials. (Abstract shortened by ProQuest.).

  6. Pico-ampere current sensitivity and CdSe quantum dots assembly assisted charge transport in ferroelectric liquid crystal

    Science.gov (United States)

    Pratap Singh, Dharmendra; Boussoualem, Yahia; Duponchel, Benoit; Sahraoui, Abdelhak Hadj; Kumar, Sandeep; Manohar, Rajiv; Daoudi, Abdelylah

    2017-08-01

    Octadecylamine capped CdSe quantum dots (QDs) dispersed 4-(1-methyl-heptyloxy)-benzoic acid 4‧-octyloxy-biphenyl-4-yl ester ferroelectric liquid crystal (FLC) were deposited over gold coated quartz substrate using dip-coating. The topographical investigation discloses that the homogeneously dispersed QDs adopt face-on to edge-on assembly in FLC matrix owing to their concentration. Current-voltage (I-V) measurement was performed using conductive atomic force microscopy (CAFM) which yields ohmic to critical diode like I-V curves depending upon the concentration of QDs in FLC. The recorded pico-ampere (pA) current sensitivity in FLC-QDs composites is attributed to micro-second drift time of electron due to weak electronic coupling between the π-electrons on the FLC and s-electrons on the metal surface. The observed pico-ampere sensitivity is the least current sensitivity recorded so far. For FLC-QDs composites, almost 24% faster electro-optic response was observed in comparison to pure FLC. The pico-ampere current sensitivity can be utilized in touch screen displays whereas the change in polarization for low applied electric field ameliorates the increased electrical susceptibility counteracting the internal electric field and its use in electronic data storage and faster electro-optical devices.

  7. Observation of paramorphic phenomenon and non-tilted orthogonal smectic phases in hydrogen bonded ferroelectric liquid crystals for photonic applications

    Science.gov (United States)

    Subhasri, P.; Venugopal, D.; Jayaprakasam, R.; Chitravel, T.; Vijayakumar, V. N.

    2018-06-01

    A new class of hydrogen bonded ferroelectric liquid crystals (HBFLC) have been designed and synthesized by intermolecular hydrogen bonds between mesogenic 4-decyloxybenzoic acid (10OBA) and non-mesogenic (R)-(+)-Methylsuccinic acid (MSA) which have been confirmed through experimental and theoretical studies. Further, Mulliken population analysis clearly reveals that the existence of hydrogen bonds, strength and dynamic properties. Textural observation and its corresponding enthalpy values are analyzed by polarizing optical microscope (POM) and differential scanning calorimetry (DSC) respectively. Paramorphic changes in Sm C* phase due to the change of refractive index, which clearly reveal that the complex could be used for filtering action in photonic devices. The transition from lone pair to π* with large stabilization energy evidently exposes the chiral phases in the present HBFLC complex. Intermolecular interaction is analyzed by using natural bond orbital (NBO) studies. The highest energy in the HOMO-LUMO shows the stable phase in the HBFLC complex. Molecular structure of the HBFLC complex possesses the monoclinic which has been evinced through x-ray analysis. The randomly oriented bunch of homogeneous molecules in Sm A* phase of the HBFLC complex is reported.

  8. Reverse bistable effect in ferroelectric liquid crystal devices with ultra-fast switching at low driving voltage.

    Science.gov (United States)

    Guo, Qi; Zhao, Xiaojin; Zhao, Huijie; Chigrinov, V G

    2015-05-15

    In this Letter, reverse bistable effect with deep-sub-millisecond switching time is first reported in ferroelectric liquid crystal (FLC) devices using a homogeneous photo-alignment technique. It is indicated by our experimental results that both the anchoring energy and the dielectric property of the FLC's alignment layer is critical for the existence of the reverse bistable effect. In addition, with the derived criteria of the reverse bistable effect, we quantitatively analyze the switching dynamics of the reverse bistable FLC and the transition condition between the traditional bistability and our presented reverse bistability. Moreover, the fabricated FLC device exhibits an ultra-fast switching of ∼160  μs and a high contrast ratio of 1000:1, both of which were measured at a low driving voltage of 11 V. The featured deep-sub-millisecond switching time is really advantageous for our presented reverse bistable FLC devices, which enables a significant quality improvement of the existing optical devices, as well as a wide range of new applications in photonics and display areas.

  9. Polarization switching detection method using a ferroelectric liquid crystal for dichroic atomic vapor laser lock frequency stabilization techniques.

    Science.gov (United States)

    Dudzik, Grzegorz; Rzepka, Janusz; Abramski, Krzysztof M

    2015-04-01

    We present a concept of the polarization switching detection method implemented for frequency-stabilized lasers, called the polarization switching dichroic atomic vapor laser lock (PSDAVLL) technique. It is a combination of the well-known dichroic atomic vapor laser lock method for laser frequency stabilization with a synchronous detection system based on the surface-stabilized ferroelectric liquid crystal (SSFLC).The SSFLC is a polarization switch and quarter wave-plate component. This technique provides a 9.6 dB better dynamic range ratio (DNR) than the well-known two-photodiode detection configuration known as the balanced polarimeter. This paper describes the proposed method used practically in the VCSEL laser frequency stabilization system. The applied PSDAVLL method has allowed us to obtain a frequency stability of 2.7×10⁻⁹ and a reproducibility of 1.2×10⁻⁸, with a DNR of detected signals of around 81 dB. It has been shown that PSDAVLL might be successfully used as a method for spectra-stable laser sources.

  10. Polarization reversal and ferroelectric domain structure observed in electroded cesium dihydrogen phosphate crystals using an X-ray anomalous dispersion effect

    International Nuclear Information System (INIS)

    Ozaki, Toru; Amau, Toshirou; Kawata, Hiroshi; Mizuno, Kaoru; Mori, Koichi.

    1997-01-01

    We have carried out an X-ray intensity measurement and X-ray topography on electroded b plates of ferroelectric cesium dihydrogen phosphate, CsH 2 PO 4 (CDP), using a synchrotron radiation with a wavelength of 2.482 A above the Cs L 3 -absorption edge. We have found that integrated intensities I(150) and I(1-bar5-bar0) show an anomalously large breakdown of Friedel's law, I(150)/I(1-bar5-bar0)=10.4 at 125 K, and display a ferroelectric hysteresis loop. The hysteresis loop determines that spontaneous polarization is antiparallel to the b axes set in both ferroelectric crystal structures related by inversions. The (150) diffraction topography shows that a single domain turns into a lamellar domain structure without fractal aspects after short-circuiting the b plate. The atomic displacement associated with polarization reversal is shown in a crystal structure model of 180deg domains observed in the X-ray topography. (author)

  11. Ferroelectric domains and phase evolution in (Fe:) KTa{sub 1−x}Nb{sub x}O{sub 3} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hongyang; Cai, Kang; Fan, Ziran; Huang, Zhideng [Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, Department of Materials Science and Engineering, Wuhan Institute of Technology, 693 Xiongchu Road, Wuhan 430073 (China); Ma, Zhibin, E-mail: mazb@wit.edu.cn [Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, Department of Materials Science and Engineering, Wuhan Institute of Technology, 693 Xiongchu Road, Wuhan 430073 (China); Jia, Tingting; Kimura, Hideo [National Institute for Materials Science, Sengen 1-2-1, Tsukuba 305-0047 (Japan); Yang, Yuguo [New Materials Research Institute, Shandong Academy of Sciences, No. 19, Keyuan Road, Jinan 250014 (China); Matsumoto, Takao; Tohei, Tetsuya; Shibata, Naoya; Ikuhara, Yuichi [Institute of Engineering Innovation, School of Engineering, University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2017-08-15

    Highlights: • Three phase transitions were observed: the R–O, O–T, T–C evolutions. • KTN ferroelectric domain switching is because of the nano-polar-regions. • The domain evolution showed KTN has triangle shape, but Fe: KTN has straight line. - Abstract: The domain structures and phase evolution in mixed ferroelectric (Fe): KTa{sub 1−x}Nb{sub x}O{sub 3} (KTN) crystals were investigated. Temperature dependent Raman spectra show that Curie temperatures of KTN and Fe: KTN are far below room temperature, but the ferroelectric domain switching was still visualized by scanning probe microscopy at room temperature. These observed domains origin from the nano-regions near the grain boundaries. In addition, the intrinsic domains (triangle for KTN and straight line/stripe for Fe: KTN) could only be observed at low temperature by transmission electron microscopy. Three phase transitions in Fe: KTN crystals were found by Raman spectroscopy and dielectric testing: 175 K for Rhombohedral-to-Orthorhombic (R–O), 210 K for Orthorhombic-to-Tetragonal (O–T) and 250 K for Tetragonal-to-Cubic (T–C), which is consistent with the domain behavior.

  12. Optimized Wavelength-Tuned Nonlinear Frequency Conversion Using a Liquid Crystal Clad Waveguide

    Science.gov (United States)

    Stephen, Mark A. (Inventor)

    2018-01-01

    An optimized wavelength-tuned nonlinear frequency conversion process using a liquid crystal clad waveguide. The process includes implanting ions on a top surface of a lithium niobate crystal to form an ion implanted lithium niobate layer. The process also includes utilizing a tunable refractive index of a liquid crystal to rapidly change an effective index of the lithium niobate crystal.

  13. Anisotropic thermal properties and ferroelectric phase transitions in layered CuInP2S6 and CuInP2Se6 crystals

    Science.gov (United States)

    Liubachko, V.; Shvalya, V.; Oleaga, A.; Salazar, A.; Kohutych, A.; Pogodin, A.; Vysochanskii, Yu. M.

    2017-12-01

    Thermal diffusivity and thermal conductivity have been studied for the layered crystals CuInP2S6, CuInP2Se6 from 30 K to 350 K, showing a relevant thermal anisotropy. Heat is much more efficiently transferred within the layers than perpendicular to them. The ferrielectric transition in CuInP2S6 is proven to be clearly first order while the ferroelectric one in CuInP2Se6 has a weak first order character. The behavior of the thermal conductivity as a function of temperature in the ferroelectric phases shows that heat conduction is phonon driven. Disorder in the paraelectric phases due to hopping motions of Cu ions significantly reduces the thermal conductivity to extremely low values.

  14. Polarization-switching dynamics and microstructures of ferroelectric (Bi0.5Na0.5)TiO3 single crystals

    Science.gov (United States)

    Yanai, Ken; Onozuka, Hiroaki; Kitanaka, Yuuki; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro; Kurushima, Kousuke; Mori, Shigeo

    2013-04-01

    Single crystals of ferroelectric (Bi0.5Na0.5)TiO3 were successfully grown by using the top-seeded solution growth method at a high oxygen pressure of 0.9 MPa and their polarization switching dynamics along the c direction and their domain structures were investigated. Piezoelectric force microscope (PFM) observations show that BNT crystals poled along the c direction. had 71-degree domains in which the spontaneous polarization ( P s ) vector was opposite to the direction of the poling electric field. Synchrotron-radiation single-crystal X-ray diffraction analyses and PFM observations revealed that the polarization switching in the BNT crystals along the c direction was achieved by a 71-degree rotation of the P s vector.

  15. Percolation Magnetism in Ferroelectric Nanoparticles

    Science.gov (United States)

    Golovina, Iryna S.; Lemishko, Serhii V.; Morozovska, Anna N.

    2017-06-01

    Nanoparticles of potassium tantalate (KTaO3) and potassium niobate (KNbO3) were synthesized by oxidation of metallic tantalum in molten potassium nitrate with the addition of potassium hydroxide. Magnetization curves obtained on these ferroelectric nanoparticles exhibit a weak ferromagnetism, while these compounds are nonmagnetic in a bulk. The experimental data are used as a start point for theoretical calculations. We consider a microscopic mechanism that leads to the emerging of a ferromagnetic ordering in ferroelectric nanoparticles. Our approach is based on the percolation of magnetic polarons assuming the dominant role of the oxygen vacancies. It describes the formation of surface magnetic polarons, in which an exchange interaction between electrons trapped in oxygen vacancies is mediated by magnetic impurity Fe3+ ions. The dependences of percolation radius on concentration of the oxygen vacancies and magnetic defects are determined in the framework of percolation theory.

  16. Percolation Magnetism in Ferroelectric Nanoparticles.

    Science.gov (United States)

    Golovina, Iryna S; Lemishko, Serhii V; Morozovska, Anna N

    2017-12-01

    Nanoparticles of potassium tantalate (KTaO 3 ) and potassium niobate (KNbO 3 ) were synthesized by oxidation of metallic tantalum in molten potassium nitrate with the addition of potassium hydroxide. Magnetization curves obtained on these ferroelectric nanoparticles exhibit a weak ferromagnetism, while these compounds are nonmagnetic in a bulk. The experimental data are used as a start point for theoretical calculations. We consider a microscopic mechanism that leads to the emerging of a ferromagnetic ordering in ferroelectric nanoparticles. Our approach is based on the percolation of magnetic polarons assuming the dominant role of the oxygen vacancies. It describes the formation of surface magnetic polarons, in which an exchange interaction between electrons trapped in oxygen vacancies is mediated by magnetic impurity Fe 3+ ions. The dependences of percolation radius on concentration of the oxygen vacancies and magnetic defects are determined in the framework of percolation theory.

  17. Macroscopic polarization and thermoluminescence of barium niobate - sodium niobate. Makroskopicheskaya polyarizatsiya i termolyuminestsentsiya niobata bariya - natriya

    Energy Technology Data Exchange (ETDEWEB)

    Gorban' , I S; Gumenyuk, A F; Omel' yanenko, V A [Kievskij Gosudarstvennyj Univ., Kiev (Ukrainian SSR)

    1989-11-01

    Thermoluminescence (TL) of initial and thermally treated purposely undoped crystals of barium niobate - sodium has been studied within 85-400 K. The TL intensity is found to depend on the temperature to which the sample has been heated. A conclusion is drawn that nonstationarity of the TL properties is due to slowly occuring processes of compensation of pyrocharge, which depend on the temperatural prehistory of the sample. A mechanism of the traps transformation in a strong pyrofield of high-impedance crystals is discussed.

  18. Visible light absorbance enhanced by nitrogen embedded in the surface layer of Mn-doped sodium niobate crystals, detected by ultra violet - visible spectroscopy, x-ray photoelectron spectroscopy, and electric conductivity tests

    Energy Technology Data Exchange (ETDEWEB)

    Molak, A., E-mail: andrzej.molak@us.edu.pl; Pilch, M. [Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice (Poland)

    2016-05-28

    Sodium niobate crystals doped with manganese ions, Na(NbMn)O{sub 3}, were annealed in a nitrogen N{sub 2} flow at 600, 670, and 930 K. It was verified that simultaneous doping with Mn ions and annealing in nitrogen enhanced the photocatalytic features of sodium niobate. The transmission in the ultraviolet-visible range was measured at room temperature. The absorbance edge is in the range from 3.4 to 2.3 eV. The optical band gap E{sub gap} = 1.2–1.3 eV was evaluated using the Tauc relation. Crystals annealed at 670 K and 930 K exhibited an additional shift of the absorption edge of ∼20–40 nm toward longer wavelengths. The optical energy gap narrowed as a result of the superimposed effect of Mn and N co-doping. The x-ray photoelectron spectroscopy test showed that N ions incorporated into the surface layer. The valence band consisted of O 2p states hybridized with Nb 4d, Mn 3d, and N 2s states. The disorder detected in the surroundings of Nb and O ions decreased due to annealing. The binding energy of oxygen ions situated within the surface layer was E{sub B} ≈ 531 eV. The other contributions were assigned to molecular contamination. The contribution centered at 535.5 eV vanished after annealing at 600 K and 670 K. The contribution centered at 534 eV vanished after annealing at 930 K. The N{sub 2} annealing partly removed carbonates from the surfaces of the samples. In the 480–950 K range, the electric conductivity activation energy, E{sub a} = 0.7–1.2 eV, was comparable with the optical E{sub gap}. The electric permittivity showed dispersion in the 0.1–800 kHz range that corresponds to the occurrence of defects.

  19. Crystal structure of ferroelectric Bi{sub 2}VO{sub 5.5}

    Energy Technology Data Exchange (ETDEWEB)

    Sooryanarayana, K.; Guru Row, T.N.; Varma, K.B.R. [Indian Inst. of Science, Bangalore (India)

    1997-12-01

    The structure of the {alpha}-phase of bismuth vanadate Bi{sub 2}VO{sub 5.5} has been determined using single crystal X-ray diffraction data in the space group Aba2. The refinement involves a well defined disorder at the vanadium site, which incorporates the features of the superlattice structure with vanadium tetrahedra and oxygen-deficient octahedra that is displaced about the twofold axis.

  20. Absorption and reflectivity of the lithium niobate surface masked with a graphene layer

    Directory of Open Access Journals (Sweden)

    O. Salas

    2017-01-01

    Full Text Available We performed simulations of the interaction of a graphene layer with the surface of lithium niobate utilizing density functional theory and molecular dynamics at 300K and atmospheric pressure. We found that the graphene layer is physisorbed on the lithium niobate surface with an adsorption energy of -0.8205 eV/(carbon-atom. Subsequently, the energy band structure, the optical absorption and reflectivity of the new system were calculated. We found important changes in these physical properties with respect to the corresponding ones of a graphene layer and of a lithium niobate crystal.

  1. Ferroelectric response in an achiral non-symmetric bent liquid crystal:C{sub 12}C{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Subrahmanyam, S.V.; Chalapathi, P.V. [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University Kakinada, Kakinada 533003 (India); Mahabaleshwara, S.; Srinivasulu, M. [Department of Chemistry, Manipal Institute of Technology, Manipal University, Manipal 576104 (India); George, A.K. [Department of Physics, College of Sciences, Sultan Qaboos University, PO Box-36, PC-123, Muscat (Oman); Potukuchi, D.M., E-mail: potukuchidm@yahoo.com [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University Kakinada, Kakinada 533003 (India)

    2014-10-01

    An achiral Non-Symmetric Bent Liquid Crystal (BLC) with a Oxadiazole based hetero cyclic central moiety, abbreviated as C{sub 12}C{sub 10} viz., dodecyl[4-{5-(4′-decyloxy)biphenyl-4-yl}-1,2,4-oxadiazol-3-yl]benzoate, exhibiting FerroElectric (FE) response is reported. Product is confirmed by {sup 1}H NMR, {sup 13}C NMR and elemental analysis. Characterization of BLC phases is carried out by Polarized Optical Microscopy (POM), Differential Scanning Calorimetry (DSC), Spontaneous Polarization (P{sub S}) and Low Frequency (10 Hz–10 MHz) Dielectric Relaxation studies. C{sub 12}C{sub 10} exhibits enantiotropic LC SmA, FE B{sub 2}, SmG, SmE phase variance. I–SmA, B{sub 2}–SmG and SmG–SmE transitions are of first order nature. FE B{sub 2} phases exhibits a moderate P{sub S} of ∼80 nC cm{sup −2}. B{sub 2} phase exhibits Curie–Weiss behavior to confirm FE nature. Off-centered low frequency (KHz) dispersion infers a scissor mode and a high frequency (MHz) mode to reflect the distinct time-scale response. Dielectric Dispersion is relatively susceptible in lower frequency KHz region. Arrhenius shift in Relaxation Frequency (f{sub R}) infers higher activation energy (E{sub a}) in non-FE phases for HF mode and lower value for KHz mode. Trends of f{sub R}, dielectric strength Δε, α-parameter and E{sub a} are discussed in view of the data reported in other LC compounds.

  2. Determination of intrinsic polarization for K{sub 2}ZnCl{sub 4} single crystal grown by Czochralski technique for ferroelectric applications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sonu [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi-7 (India); Ray, Geeta [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi-7 (India); Physics Department, Miranda House, University of Delhi, Delhi-7 (India); Sinha, Nidhi [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi-7 (India); Department of Electronics, SGTB Khalsa College, University of Delhi, Delhi-7 (India); Kumar, Binay, E-mail: b3kumar69@yahoo.co.in [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi-7 (India)

    2017-04-01

    Large sized single crystal of K{sub 2}ZnCl{sub 4} (KZC) was grown by Czochralski (Cz) technique. Structural parameters of KZC were determined by Single crystal X-ray diffraction (SCXRD). From DSC analysis and temperature dependent dielectric measurement, KZC crystal was found to show Curie phase transition at 151 °C. TG/DTA confirmed the melting point that was found to be 443 °C. The value of piezoelectric charge coefficient (d{sub 33}) for KZC crystal was found to be 32 pC/N demonstrating their applicability in transducers and piezoelectric devices. Ferroelectric P-E loop for the grown crystal was traced at room temperature and the intrinsic polarization obtained by PUND measurement was found to be 0.1398 μC/cm{sup 2} indicating its applicability in switching devices. The energy band gap for KZC single crystal was found to be 6.13 eV. Vickers micro-hardness test revealed soft nature of KZC single crystals. - Highlights: • Large sized K{sub 2}ZnCl{sub 4} (KZC) single crystal was grown by Czochralski technique. • It possesses high Curie temperature as 151 °C. • d{sub 33} coefficient was found to be 32 pC/N. • Intrinsic polarization measured by PUND. • Its direct band gap energy was calculated to be 6.13 eV.

  3. Phase transition sequence in ferroelectric Aurivillius compounds investigated by single crystal X-ray diffraction

    Science.gov (United States)

    Boullay, P.; Tellier, J.; Mercurio, D.; Manier, M.; Zuñiga, F. J.; Perez-Mato, J. M.

    2012-09-01

    The investigation of the phase transition sequence in SrBi2Ta2O9 (SBT) and SrBi2Nb2O9 (SBN) is reported using single-crystal X-ray diffraction. By monitoring specific reflections as a function of temperature, sensitive either to the superstructure formation or to polar displacements, it was possible to check the existence or not of an intermediate phase. This latter was confirmed in SBT, but within experimental accuracy could not be detected in SBN.

  4. Crystal structure and ferroelectric properties of Ca(Cu3−xMx)Ti4O12 (M = Fe and Ni) ceramics

    International Nuclear Information System (INIS)

    Moriyama, Tohru; Kan, Akinori; Ogawa, Hirotaka

    2013-01-01

    Highlights: ► M-substituted Ca(Cu 3−x M x )Ti 4 O 12 (CCMTO) ceramics, where M = Fe and Ni, were synthesized. ► The influence of M substitution for Cu on crystal structure and ferroelectric properties of CCMTO ceramics were investigated. ► Analysis of CCMTO ceramics revealed the single phase of CCMTO ceramics belongs to I23 non-centrosymmetric space group of I23. ► As a result, the P r and E c values of CCFTO ceramics at x = 0.05 were 1.8 μC/cm 2 and 40 kV/cm, respectively. -- Abstract: M-substituted Ca(Cu 3−x M x )Ti 4 O 12 (CCMTO) ceramics, where M = Fe and Ni, were synthesized and the influence of M substitutions for Cu on the crystal structure and ferroelectric properties of CCMTO ceramics were investigated in this study. From the variations in the lattice parameters of CCMTO ceramics, the solubility limit of Ni substitution for Cu in CaCu 3−x Ni x Ti 4 O 12 (CCNTO) ceramics was x = 0.2, whereas that of CaCu 3−x Fe x Ti 4 O 12 (CCFTO) ceramics was x = 0.05. The crystal structural analysis of CCMTO ceramics revealed that the single phase of CCMTO ceramics belongs to the I23 non-centrosymmetric space group of I23; as a result, the P r and E c values of CCFTO ceramics at x = 0.05 were 1.8 μC/cm 2 and 40 kV/cm, respectively. The ferroelectric behavior of CCMTO ceramics by the M substitutions for Cu may be related to the displacement of a Ti 4+ cation in the TiO 6 octahedra and tilting of the Ti–O–Ti angle because of the non-centrosymmetric space group

  5. Snapshot Mueller matrix polarimetry by wavelength polarization coding and application to the study of switching dynamics in a ferroelectric liquid crystal cell.

    Directory of Open Access Journals (Sweden)

    Le Jeune B.

    2010-06-01

    Full Text Available This paper describes a snapshot Mueller matrix polarimeter by wavelength polarization coding. This device is aimed at encoding polarization states in the spectral domain through use of a broadband source and high-order retarders. This allows one to measure a full Mueller matrix from a single spectrum whose acquisition time only depends on the detection system aperture. The theoretical fundamentals of this technique are developed prior to validation by experiments. The setup calibration is described as well as optimization and stabilization procedures. Then, it is used to study, by time-resolved Mueller matrix polarimetry, the switching dynamics in a ferroelectric liquid crystal cell.

  6. Indentation induced mechanical and electrical response in ferroelectric crystal investigated by acoustic mode AFM

    Science.gov (United States)

    Yu, H. F.; Zeng, H. R.; Ma, X. D.; Chu, R. Q.; Li, G. R.; Luo, H. S.; Yin, Q. R.

    2005-01-01

    The mechanical and electrical response of Pb (Mg1/3Nb2/3)- O3-PbTiO3 single crystals to micro-indentation are investigated using the newly developed low frequency scanning probe acoustic microscopy which is based on the atomic force microscope. There are three ways to release the stress produced by indentation. Plastic deformation emerged directly underneath the indentor and along the indentation diagonals. In addition, indentation-induced micro-cracks and new non-180° domain structures which are perpendicular to each other are also observed in the indented surface. Based on the experimental results, the relationship between the cracks and the domain patterns was discussed.

  7. Double hydrogen bonded ferroelectric liquid crystals: A study of field induced transition (FiT)

    Science.gov (United States)

    Vijayakumar, V. N.; Madhu Mohan, M. L. N.

    2009-12-01

    A novel series of chiral hydrogen bonded liquid crystals have been isolated. Hydrogen bond was formed between chiral nonmesogen ingredient levo tartaric acid and mesogenic p-n-alkoxybenzoic acids. Phase diagram was constructed from the transition temperatures obtained by DSC and polarizing optical microscopic (POM) studies. Thermal and electrical properties exhibited by three complexes namely LTA+8BA, LTA+7BA and LTA+5BA were discussed. Salient feature of the present work was the observation of a reentrant smectic ordering in LTA+8BA complex designated as C r∗ phase. This reentrant phenomenon was confirmed by DSC thermograms, optical textures of POM and temperature variation of capacitance and dielectric loss studies. Tilt angle was measured in smectic C ∗ and reentrant smectic C r∗ phases. Another interesting feature of the present investigation was the observation of a field induced transition (FiT) in the LTA+ nBA homologous series. Three threshold field values were noticed which give rise to two new phases (E 1 and E 2) induced by electric field and on further enhancement of the applied field the mesogen behaves like an optical shutter. FiT is reversible in the sense that when applied field is removed the original texture was restored.

  8. CuInS2/ZnS QD-ferroelectric liquid crystal mixtures for faster electro-optical devices and their energy storage aspects

    Science.gov (United States)

    Singh, Dharmendra Pratap; Vimal, Tripti; Mange, Yatin J.; Varia, Mahesh C.; Nann, Thomas; Pandey, K. K.; Manohar, Rajiv; Douali, Redouane

    2018-01-01

    CuInS2/ZnS core/shell quantum dots (CIS/ZnS QDs) dispersed ferroelectric liquid crystal (FLC) mixtures have been characterized for their application in electro-optical devices, energy storage, and solar cells. Physical properties of the CIS/ZnS QD-FLC (ferroelectric liquid crystal) mixtures have also been investigated with varying QD concentrations in order to optimize the critical concentration of QDs in mixtures. The presence of QDs breaks the geometrical symmetry in the FLC matrix, which results in a change in the physical properties of the mixtures. We observed the reduced values of primary and secondary order parameters (tilt angle and spontaneous polarization, respectively) for mixtures, which also depend on the concentration of QDs. The reduction of spontaneous polarization in QDs-FLC mixtures is attributed to the adverse role of flexoelectric contribution in the mixtures. The 92% faster electro-optic response and enhanced capacitance indicate the possible application of these mixtures in electro-optical devices and solar cells. Photoluminescence emission of pure FLC and QDs-FLC mixtures has been thermally tailored, which is explained by suitable models.

  9. Preparation and crystal structure of the phosphato-niobate Tl sub 3 NaNb sub 4 O sub 9 (PO sub 4 ) sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Fakhfakh, M. (Tunis Univ. (Tunisia). Faculte des Sciences); Verbaere, A. (Nantes Univ., 44 (France)); Jouini, N. (Ecole Normale Superieure de l' Enseignement Technique, Tunis (TN))

    1992-01-01

    Chemical preparation and crystal structure are described. The symmetry is orthorhombic, space group C2cm. The crystal structure has been determined using. The structure is built up from NbO{sub 6} octahedra sharing corners and PO{sub 4} tetrahedra sharing three of their corners with octahedra to form chains running along c. These chains are connected together by isolted NbO{sub 6} octahedra leasing to a three-dimensional framework which delimits cavities and tunnels occupied by the Tl and Na ions.

  10. Complete sets of elastic constants and photoelastic coefficients of pure and MgO-doped lithium niobate crystals at room temperature

    International Nuclear Information System (INIS)

    Andrushchak, A. S.; Laba, H. P.; Yurkevych, O. V.; Mytsyk, B. G.; Solskii, I. M.; Kityk, A. V.; Sahraoui, B.

    2009-01-01

    This paper presents the results of ultrasonic measurements of LiNbO 3 and LiNbO 3 :MgO crystals. The tensors of piezoelectric coefficients, elastic stiffness constants, and elastic compliances are determined for both crystals at room temperature. Combining these data with the results of piezo-optical measurements, a complete set of photoelastic tensor coefficients is also calculated. Doping of LiNbO 3 crystals by MgO does not lead to a considerable modification of their elastic and photoelastic properties. However, LiNbO 3 :MgO is characterized by a considerably higher resistance with respect to powerful light radiation, making it promising for future application in acousto-optic devices that deal with superpowerful laser radiation. Presented here are the complete tensor sets of elastic constants and photoelastic coefficients of LiNbO 3 and LiNbO 3 :MgO crystals that may be used for a geometry optimization of acousto-optical interaction providing the best diffraction efficiency of acousto-optical cells made of these materials.

  11. The effect of the ferroelectric domain walls in the scanning near field optical microscopy response of periodically poled Ba2NaNb5O15 and LiNbO3 crystals

    International Nuclear Information System (INIS)

    Han, T P J; Jaque, F; Lamela, J; Jaque, D; Lifante, G; Cusso, F; Kamiskii, A A

    2009-01-01

    A study of Ba 2 NaNb 5 O 15 and LiNbO 3 crystals with periodic ferroelectric domain structures using the scanning near field optical microscopy technique is reported. Optical contrast is observed in the regions of ferroelectric domain boundaries and it is analysed using beam propagation method modelling. This reveals that the optical contrast, a consequence of changes in the refractive index, is not due to variation of the waveguide-coupling efficiency, and supports the hypothesis that it is associated with the domain array, which is related to the size of the domain. (fast track communication)

  12. Ferroelectric devices

    CERN Document Server

    Uchino, Kenji

    2009-01-01

    Updating its bestselling predecessor, Ferroelectric Devices, Second Edition assesses the last decade of developments-and setbacks-in the commercialization of ferroelectricity. Field pioneer and esteemed author Uchino provides insight into why this relatively nascent and interdisciplinary process has failed so far without a systematic accumulation of fundamental knowledge regarding materials and device development.Filling the informational void, this collection of information reviews state-of-the-art research and development trends reflecting nano and optical technologies, environmental regulat

  13. Comparison of the properties of tonpilz transducers fabricated with 001 fiber-textured lead magnesium niobate-lead titanate ceramic and single crystals.

    Science.gov (United States)

    Brosnan, Kristen H; Messing, Gary L; Markley, Douglas C; Meyer, Richard J

    2009-11-01

    Tonpilz transducers are fabricated from 001 fiber-textured 0.72Pb(Mg(1/3)Nb(2/3))O(3)-0.28PbTiO(3) (PMN-28PT) ceramics, obtained by the templated grain growth process, and PMN-28PT ceramic and Bridgman grown single crystals of the same composition. In-water characterization of single element transducers shows higher source levels, higher in-water coupling, and more usable bandwidth for the 81 vol % textured PMN-28PT device than for the ceramic PMN-28PT element. The 81 vol % textured PMN-28PT tonpilz element measured under large signals shows linearity in sound pressure levels up to 0.23 MV/m drive field but undergoes a phase transition due to a lowered transition temperature from the SrTiO(3) template particles. Although the textured ceramic performs well in this application, it could be further improved with compositional tailoring to raise the transition temperature and better processing to improve the texture quality. With these improvements textured piezoelectric ceramics will be viable options for medical ultrasound, actuators, and sonar applications because of their ease of processing, compositional homogeneity, and potentially lower cost than single crystal.

  14. Giant piezoelectricity in potassium-sodium niobate lead-free ceramics.

    Science.gov (United States)

    Wang, Xiaopeng; Wu, Jiagang; Xiao, Dingquan; Zhu, Jianguo; Cheng, Xiaojing; Zheng, Ting; Zhang, Binyu; Lou, Xiaojie; Wang, Xiangjian

    2014-02-19

    Environment protection and human health concern is the driving force to eliminate the lead from commercial piezoelectric materials. In 2004, Saito et al. [ Saito et al., Nature , 2004 , 432 , 84 . ] developed an alkali niobate-based perovskite solid solution with a peak piezoelectric constant d33 of 416 pC/N when prepared in the textured polycrystalline form, intriguing the enthusiasm of developing high-performance lead-free piezoceramics. Although much attention has been paid on the alkali niobate-based system in the past ten years, no significant breakthrough in its d33 has yet been attained. Here, we report an alkali niobate-based lead-free piezoceramic with the largest d33 of ∼490 pC/N ever reported so far using conventional solid-state method. In addition, this material system also exhibits excellent integrated performance with d33∼390-490 pC/N and TC∼217-304 °C by optimizing the compositions. This giant d33 of the alkali niobate-based lead-free piezoceramics is ascribed to not only the construction of a new rhombohedral-tetragonal phase boundary but also enhanced dielectric and ferroelectric properties. Our finding may pave the way for "lead-free at last".

  15. Influence of KF substitution on the ferroelectric phase transition of lead titanate single crystals studied by Brillouin light scattering

    Directory of Open Access Journals (Sweden)

    Seonhyeop Shin

    2015-06-01

    Full Text Available The elastic properties of KF-substituted perovskite lead titanate (PbTiO3 were investigated by dielectric measurements and Brillouin light scattering. The ferroelectric phase transition occurred at substantially lower temperature due to KF substitution, which was attributed to the modification of the covalency in Pb–O and Ti–O bonds. The longitudinal acoustic (LA mode of KF-substituted PbTiO3 showed a frequency softening in the paraelectric phase, which was accompanied by increasing acoustic damping. This indicated that polarization fluctuations responsible for the acoustic anomalies were enhanced by KF substitution.

  16. Phase fragility and mechatronic reliability for Pb(Mg1/3Nb2/3O3–PbTiO3 ferroelectric single crystals — A review

    Directory of Open Access Journals (Sweden)

    F. Fang

    2014-01-01

    Full Text Available Single crystals of (1-xPb(Mg1/3Nb2/3O3–xPbTiO3(PMN–xPT near their morphotropic phase boundaries (MPBs are under extensive investigations for their extraordinary high dielectric and piezoelectric behavior. Applications of those single crystals facilitated the breakthrough in ultrasonic transducer materials and devices. Ferroelectric materials are known to be fragile which often leads to various reliability failures in applications involving electric loadings. In a mechanical sense, the failure modes concern the fracture under an intensive electric field, and the fatigue crack propagation under an alternating electric field. In an electrical sense, the failure is exhibited by degenerated hysteresis loop by shrinking the remnant polarization and expanding the coercive field. All these modes degrade the performance for ferroelectric devices. As a departure from the tetragonal (T ferroelectric materials, exemplified by BaTiO3 and Pb(ZrTiO3, the domain structures of PMN–PT around the MPB are versatile and intricate, depending sensitively on the composition variation, orientation and previous loading history. In this review, the attention is mainly focused on three aspects. First, the phase fragility and multiphase coexistence are presented for both [100]- and [101]-oriented PMN–PT single crystals. Second, investigations on electric field-induced fatigue crack propagation are described, along with the orientation effect on the crack propagation behavior. Third, the inverse effects of the phase transition and fatigue crack growth on the polarization behavior, or the interaction between the mechanical and electrical degradations will be elucidated. The review aims for better understanding the underlying mechanism for the ultrahigh performance of the PMN–PT single crystals, to bridge the studies of ferroelectric materials from the mechanical and electrical senses, as well as to evaluate the reliability of PMN–PT single crystals under device

  17. Crystal structure, dielectric, ferroelectric and energy storage properties of La-doped BaTiO3 semiconducting ceramics

    Directory of Open Access Journals (Sweden)

    Venkata Sreenivas Puli

    2015-09-01

    Full Text Available Polycrystalline La-doped BaTiO3 (Ba(1-xLax\tTiO3 [x=0,0.0005,0.001,0.003] ceramics (denoted as BTO,BLT1,BLT2,BLT3 were synthesized by conventional solid-state reaction method and characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, and Raman spectroscopy. XRD and Raman spectra revealed single-phase tetragonal perovskite crystalline structure. Well-saturated polarization–electric field (P–E hysteresis loops were observed with the measurement frequency of 50 Hz at room temperature and confirmed ferroelectric nature of these ceramics and a high recoverable electrical energy storage density of 0.350 J/cm3 with energy efficiency (n∼9%, which is useful in energy storage capacitor applications. Dielectric studies revealed anomalies around 415–420 K and near the Curie temperature. The latter is attributed to the ferroelectric to paraelectric phase transition. Better dielectric performances were obtained for La-doped samples sintered at 1350°C for 4 h. Grain growth is inhibited with lanthanum (La incorporation into the BTO lattice. Room temperature semiconducting behavior with positive temperature coefficient of resistivity (PTCR behavior at TC is attributed to electron compensation mechanism.

  18. Processing and characterization of lead-free ceramics on the base of sodium-potassium niobate

    Science.gov (United States)

    Politova, E. D.; Golubko, N. V.; Kaleva, G. M.; Mosunov, A. V.; Sadovskaya, N. V.; Stefanovich, S. Yu.; Kiselev, D. A.; Kislyuk, A. M.; Panda, P. K.

    Lead-free sodium-potassium niobate-based piezoelectric materials are most intensively studied in order to replace the widely used Pb-based ones. In this work, the effects of modification of compositions by donor and acceptor dopants in the A- and B-sites of perovskite lattice on structure, dielectric, ferroelectric, and piezoelectric properties of ceramics from Morphotropic Phase Boundary in the (1-x)(K0.5Na0.5)NbO3-xBaTiO3 system and in compositions with x=0.05 and 0.06 additionally doped by Ni3+ cations have been studied.

  19. Processing and characterization of lead-free ceramics on the base of sodium–potassium niobate

    Directory of Open Access Journals (Sweden)

    E. D. Politova

    2018-02-01

    Full Text Available Lead-free sodium–potassium niobate-based piezoelectric materials are most intensively studied in order to replace the widely used Pb-based ones. In this work, the effects of modification of compositions by donor and acceptor dopants in the A- and B-sites of perovskite lattice on structure, dielectric, ferroelectric, and piezoelectric properties of ceramics from Morphotropic Phase Boundary in the (1−x(K0.5Na0.5NbO3–xBaTiO3 system and in compositions with x=0.05 and 0.06 additionally doped by Ni3+ cations have been studied.

  20. Programming scale-free optics in disordered ferroelectrics.

    Science.gov (United States)

    Parravicini, Jacopo; Conti, Claudio; Agranat, Aharon J; DelRe, Eugenio

    2012-06-15

    Using the history dependence of a dipolar glass hosted in a compositionally disordered lithium-enriched potassium tantalate niobate (KTN:Li) crystal, we demonstrate scale-free optical propagation at tunable temperatures. The operating equilibration temperature is determined by previous crystal spiralling in the temperature/cooling-rate phase space.

  1. Programming scale-free optics in disordered ferroelectrics

    OpenAIRE

    Parravicini, Jacopo; Conti, Claudio; Agranat, Aharon J.; DelRe, Eugenio

    2012-01-01

    Using the history-dependence of a dipolar glass hosted in a compositionally-disordered lithium-enriched potassium-tantalate-niobate (KTN:Li) crystal, we demonstrate scale-free optical propagation at tunable temperatures. The operating equilibration temperature is determined by previous crystal spiralling in the temperature/cooling-rate phase-space.

  2. Domain wall width of lithium niobate poled during growth

    CERN Document Server

    Brooks, R; Hole, D E; Callejo, D; Bermudez, V; Diéguez, E

    2003-01-01

    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 mu m 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.

  3. Structure-Function Relationships of Ferroelectric Polymers.

    Science.gov (United States)

    Pavlopoulou, Eleni; Maiz, Jon; Spampinato, Nicoletta; Maglione, Mario; Hadziioannou, Georges

    Poly(vinylidene fluoride), PVDF, and its copolymers with trifluoroethylene, P(VDF-co-TrFE) have been long appreciated for their excellent ferroelectric properties. Although they have been mainly studied in the 80s and 90s, understanding their performance is still lacking. Yet the increasing use of P(VDF-co-TrFE) thin films in organic electronic devices during the last ten years revives the need for apprehending the function of these materials. In this work we investigate the structure of P(VDF-co-TrFE) films and correlate it to their ferroelectric properties. Our results show that ferroelectric performance is solely driven by the fraction of polymer that has been crystallized in the ferroelectric phases of PVDF. The relations between remnant polarization, coercive field and dipole switching rate of P(VDF-co-TrFE) with the ferroelectric crystallinity are demonstrated. The French Research Agency (ANR), the Aquitaine Region, Arkema and STMicroelectronics are kindly acknowledged for financial support.

  4. Single crystal magnetic, dielectric and thermal studies of the relaxor ferroelectric Pb(Fe2/3W1/3)O3

    International Nuclear Information System (INIS)

    Ye, Z.G.; Sato, M.; Kita, E.; Bursill, L.A.; Schmid, H.

    1998-01-01

    The magnetic, dielectric and thermal properties of the complex perovskite Pb(Fe 2/3 W 1/3 )O 3 [PFW] have been studied on single crystals by means of a SQUID magnetometer, dielectric measurements and thermal analysis. Anomalies in the temperature dependence of the magnetization have revealed magnetic phase transitions at T N1 =350 K and T N2 =20 K. These two steps of antiferromagnetic ordering are attributed to the microstructural feature of the complex perovskite, characterized by ordered and disordered arrangements on the B-site, giving rise to a strong superexchange interaction of - Fe 3 + - O - Fe 3+ - type with a higher ordering temperature, and to a weak superexchange interaction of the B-site ordered elpasolite type - Fe 3+ + - O - W - O - Fe 3+ - with a lower Neel temperature. The low temperature antiferromagnetic phase exhibits a weak ferromagnetism. The dielectric properties of PFW show a relaxor ferroelectric behaviour with a dispersive maximum of permittivity at Tm (170 -190 K). The magnetic phase transition at T N2 =20 K results in anomalies both of the real part of permittivity and the dissipation factor, suggesting a magneto-electric coupling via magneto-structural interactions

  5. Characterization of the local layer structure of a broad wall in a surface stabilized ferroelectric liquid crystal using synchrotron X-ray micro-diffraction

    International Nuclear Information System (INIS)

    Iida, Atsuo; Noma, Takashi; Miyata, Hirokatsu.

    1996-01-01

    The local layer structure of the broad wall of a zig-zag defect in a thin-surface stabilized ferroelectric liquid crystal cell was characterized using a synchrotron X-ray microbeam of less than 5 μm spatial resolution. By using a rocking curve measurement at the broad wall, multiple or broad peaks were observed between a pair of peaks due to a chevron structure. These new peaks are clear evidence of a modified pseudo-bookshelf structure at the wall. For 1.5 μm thick cells, a bookshelf layer is relatively flat, but is accompanied by small areas of inclined layer connecting the bookshelf and the chevron structures. For 10 μm thick cells, the pseudo-bookshelf structure bends or undulates both perpendicular and parallel to the rubbing direction. No appreciable change in the layer spacing was observed in the modified pseudo-bookshelf structure. The temperature dependence of the broad wall layer structure was also measured. (author)

  6. Characterization of the local layer structure of a broad wall in a surface stabilized ferroelectric liquid crystal using synchrotron X-ray micro-diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Atsuo [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan); Noma, Takashi; Miyata, Hirokatsu

    1996-01-01

    The local layer structure of the broad wall of a zig-zag defect in a thin-surface stabilized ferroelectric liquid crystal cell was characterized using a synchrotron X-ray microbeam of less than 5 {mu}m spatial resolution. By using a rocking curve measurement at the broad wall, multiple or broad peaks were observed between a pair of peaks due to a chevron structure. These new peaks are clear evidence of a modified pseudo-bookshelf structure at the wall. For 1.5 {mu}m thick cells, a bookshelf layer is relatively flat, but is accompanied by small areas of inclined layer connecting the bookshelf and the chevron structures. For 10 {mu}m thick cells, the pseudo-bookshelf structure bends or undulates both perpendicular and parallel to the rubbing direction. No appreciable change in the layer spacing was observed in the modified pseudo-bookshelf structure. The temperature dependence of the broad wall layer structure was also measured. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Patel, N. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Branch, D. W.; Cular, S. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Schamiloglu, E. [Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87106 (United States)

    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.

  8. Ferroelectricity in undoped hafnium oxide

    International Nuclear Information System (INIS)

    Polakowski, Patrick; Müller, Johannes

    2015-01-01

    We report the observation of ferroelectric characteristics in undoped hafnium oxide thin films in a thickness range of 4–20 nm. The undoped films were fabricated using atomic layer deposition (ALD) and embedded into titanium nitride based metal-insulator-metal (MIM) capacitors for electrical evaluation. Structural as well as electrical evidence for the appearance of a ferroelectric phase in pure hafnium oxide was collected with respect to film thickness and thermal budget applied during titanium nitride electrode formation. Using grazing incidence X-Ray diffraction (GIXRD) analysis, we observed an enhanced suppression of the monoclinic phase fraction in favor of an orthorhombic, potentially, ferroelectric phase with decreasing thickness/grain size and for a titanium nitride electrode formation below crystallization temperature. The electrical presence of ferroelectricity was confirmed using polarization measurements. A remanent polarization P r of up to 10 μC cm −2 as well as a read/write endurance of 1.6 × 10 5 cycles was measured for the pure oxide. The experimental results reported here strongly support the intrinsic nature of the ferroelectric phase in hafnium oxide and expand its applicability beyond the doped systems

  9. Ferroelectric domain engineering by focused infrared femtosecond pulses

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xin; Shvedov, Vladlen; Sheng, Yan, E-mail: yan.sheng@anu.edu.au [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Karpinski, Pawel [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Wroclaw University of Technology, Wybrzeze Wyspianskiego, Wroclaw (Poland); Koynov, Kaloian [Max-Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany); Wang, Bingxia; Trull, Jose; Cojocaru, Crina [Departament de Fisica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Rambla Sant Nebridi, 08222 Terrassa, Barcelona (Spain); Krolikowski, Wieslaw [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Texas A& M University at Qatar, Doha (Qatar)

    2015-10-05

    We demonstrate infrared femtosecond laser-induced inversion of ferroelectric domains. This process can be realised solely by using tightly focused laser pulses without application of any electric field prior to, in conjunction with, or subsequent to the laser irradiation. As most ferroelectric crystals like LiNbO{sub 3}, LiTaO{sub 3}, and KTiOPO{sub 4} are transparent in the infrared, this optical poling method allows one to form ferroelectric domain patterns much deeper inside a ferroelectric crystal than by using ultraviolet light and hence can be used to fabricate practical devices. We also propose in situ diagnostics of the ferroelectric domain inversion process by monitoring the Čerenkov second harmonic signal, which is sensitive to the appearance of ferroelectric domain walls.

  10. Topology and temperature dependence of the diffuse X-ray scattering in Na0.5Bi0.5TiO3 ferroelectric single crystals.

    Science.gov (United States)

    Gorfman, Semën; Keeble, Dean S; Bombardi, Alessandro; Thomas, Pam A

    2015-10-01

    The results of high-resolution measurements of the diffuse X-ray scattering produced by a perovskite-based Na 0.5 Bi 0.5 TiO 3 ferroelectric single crystal between 40 and 620 K are reported. The study was designed as an attempt to resolve numerous controversies regarding the average structure of Na 0.5 Bi 0.5 TiO 3 , such as the mechanism of the phase transitions between the tetragonal, P 4 bm , and rhombohedral | monoclinic, R 3 c  |  Cc , space groups and the correlation between structural changes and macroscopic physical properties. The starting point was to search for any transformations of structural disorder in the temperature range of thermal depoling (420-480 K), where the average structure is known to remain unchanged. The intensity distribution around the {032} pseudocubic reflection was collected using a PILATUS 100K detector at the I16 beamline of the Diamond Light Source (UK). The data revealed previously unknown features of the diffuse scattering, including a system of dual asymmetric L-shaped diffuse scattering streaks. The topology, temperature dependence, and relationship between Bragg and diffuse intensities suggest the presence of complex microstructure in the low-temperature R 3 c  |  Cc phase. This microstructure may be formed by the persistence of the higher-temperature P 4 bm phase, built into a lower-temperature R 3 c  |  Cc matrix, accompanied by the related long-range strain fields. Finally, it is shown that a correlation between the temperature dependence of the X-ray scattering features and the temperature regime of thermal depoling is present.

  11. Orientational and structural properties of ferroelectric liquid crystal with broad temperature range of the SmC* phase by .sup.13./sup.C NMR, x-ray scattering and dielectric spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Bubnov, Alexej M.; Domenici, V.; Hamplová, Věra; Kašpar, Miroslav; Veracini, C.A.; Glogarová, Milada

    2009-01-01

    Roč. 21, č. 3 (2009), 035102/1-035102/8 ISSN 0953-8984 R&D Projects: GA AV ČR(CZ) GA202/09/0047; GA ČR GA202/05/0431; GA MŠk OC 175; GA AV ČR IAA100100710 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectric liquid crystal * high spontaneous polarization * 13 C nuclear magnetic resonance * x-ray scattering * dielectric spectroscopy * viscosity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.964, year: 2009

  12. Study of structural differences between stoichiometric and congruent lithium niobate

    CERN Document Server

    Kling, A; Correia, J G; Da Silva, M F A; Diéguez, E; Agulló-López, F; Soares, J C

    1996-01-01

    The structural differences between stoichiometric and congruent (lithium deficient) lithium niobate single crystals were studied by RBS- and NRA-channeling as well as perturbed angular correlation (PAC) measurements. The d-PAC111Cd-PAC investigations point out that a second Li site can be detected in congruent material, while only one is present in stoichiometric. Channeling studies of different axes and the comparison of the results with computer simulations corroborated former indications that this additional lattice site can be attributed to the formation of ilmenite type stacking faults. A comparative study of the energy dependence of the dechanneling showed that a remarkable disorder is also present in the Nb sublattice of the congruent crystals and that these defects have a point-like character.

  13. Synthesis of lithium niobate and monocrystal growth by Czochralski method

    International Nuclear Information System (INIS)

    Balzuweit, K.

    1988-01-01

    The qualitative analysis of lithium niobate by x-ray analysis and optical microscopy is presented. The lithium niobate compound was obtained by synthesis using niobium oxides and lithium carbonates. The lithium niobate monocrystal growth was done by Czochralski method. (M.C.K.)

  14. Guest–host interaction in ferroelectric liquid crystal–nanoparticle

    Indian Academy of Sciences (India)

    Ferroelectric Cu-doped ZnO (Cu–ZnO) nanoparticles have been added to the pure ferroelectric liquid crystal (FLC) Felix 17/100. The nanoparticles are bigger in size as compared to FLC molecules; therefore, they distort the existing geometry of FLC matrix and set up an antiparallel correlation with the dipole moments of the ...

  15. High Frequency Magneto Dielectric Effects In Self Assembled Ferrite Ferroelectric Core Shell Nanoparticles

    Science.gov (United States)

    2014-09-10

    ferrimagnetic metals, alloys or oxides and ferroelectrics such as barium titanate (BTO), lead zirconate titanate ( PZT ), and lead magnesium niobate-lead...estimate the magneto-capacitance effect in BTO or PZT films on substrates of ferromagnetic alloys.25 This work is on the observation and theory of MDE...transmission and reflection coefficients were done to estimate the complex permittivity. During the measurements a bias static magnetic field was

  16. Acoustic wave filter based on periodically poled lithium niobate.

    Science.gov (United States)

    Courjon, Emilie; Bassignot, Florent; Ulliac, Gwenn; Benchabane, Sarah; Ballandras, Sylvain

    2012-09-01

    Solutions for the development of compact RF passive transducers as an alternative to standard surface or bulk acoustic wave devices are receiving increasing interest. This article presents results on the development of an acoustic band-pass filter based on periodically poled ferroelectric domains in lithium niobate. The fabrication of periodically poled transducers (PPTs) operating in the range of 20 to 650 MHz has been achieved on 3-in (76.2-mm) 500-μm-thick wafers. This kind of transducer is able to excite elliptical as well as longitudinal modes, yielding phase velocities of about 3800 and 6500 ms(-1), respectively. A new type of acoustic band-pass filter is proposed, based on the use of PPTs instead of the SAWs excited by classical interdigital transducers. The design and the fabrication of such a filter are presented, as well as experimental measurements of its electrical response and transfer function. The feasibility of such a PPT-based filter is thereby demonstrated and the limitations of this method are discussed.

  17. Reduced Dimensionality Lithium Niobate Microsystems

    Energy Technology Data Exchange (ETDEWEB)

    Eichenfield, Matt [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-01-01

    The following report describes work performed under the LDRD program at Sandia National Laboratories October 2014 and September 2016. The work presented demonstrates the ability of Sandia Labs to develop state-of-the-art photonic devices based on thin film lithium niobate (LiNbO3 ). Section 1 provides an introduction to integrated LiNbO3 devices and motivation for developing thin film nonlinear optical systems. Section 2 describes the design, fabrication, and photonic performance of thin film optical microdisks fabricated from bulk LiNbO3 using a bulk implantation method developed at Sandia. Sections 3 and 4 describe the development of similar thin film LiNbO3 structures fabricated from LiNbO3 on insulator (LNOI) substrates and our demonstration of optical frequency conversion with state-of-the-art efficiency. Finally, Section 5 describes similar microdisk resonators fabricated from LNOI wafers with a buried metal layer, in which we demonstrate electro-optic modulation.

  18. Ferroelectric ultrathin perovskite films

    Science.gov (United States)

    Rappe, Andrew M; Kolpak, Alexie Michelle

    2013-12-10

    Disclosed herein are perovskite ferroelectric thin-film. Also disclosed are methods of controlling the properties of ferroelectric thin films. These films can be used in a variety materials and devices, such as catalysts and storage media, respectively.

  19. X-ray analysis of phase coexistence and electric poling processing in alkaline niobate-based compositions

    International Nuclear Information System (INIS)

    Fu Jian; Zuo Ruzhong; Liu Yi

    2010-01-01

    The characteristic and origin of two-phase coexistence and the content of each phase in typical alkaline niobate-based lead-free compositions were investigated through the refinement of X-ray diffraction peaks and the measurement of dielectric constant versus temperature curves. The diffuse nature of polymorphic phase transition has resulted in the coexistence of two ferroelectric phases within a wide composition and temperature range. As a result, the optimum piezoelectric properties appear in the composition rich in tetragonal phases and there is a remarkable poling temperature effect. Discussions on the difference between morphotropic phase boundary and polymorphic phase boundary were made in combination with the variation of electrical properties.

  20. Crystallization and mechanical behavior of the ferroelectric polymer nonwoven fiber fabrics for highly durable wearable sensor applications

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Z.H. [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Center for Nanoscience & Nanotechnology, National Sun Yat-Sen University, Taiwan (China); National Science Council Core Facilities Laboratory for Nano-Science and Nano-Technology in Kaohsiung-Pingtung Area, Taiwan (China); Micro/Meso Mechanical Manufacturing R& D Department, Metal Industries Research and Development Centre, Kaohsiung 81160, Taiwan (China); Pan, C.T., E-mail: panct@mail.nsysu.edu.tw [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Center for Nanoscience & Nanotechnology, National Sun Yat-Sen University, Taiwan (China); National Science Council Core Facilities Laboratory for Nano-Science and Nano-Technology in Kaohsiung-Pingtung Area, Taiwan (China); Yen, C.K. [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Center for Nanoscience & Nanotechnology, National Sun Yat-Sen University, Taiwan (China); National Science Council Core Facilities Laboratory for Nano-Science and Nano-Technology in Kaohsiung-Pingtung Area, Taiwan (China); Lin, L.W. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Berkeley Sensor and Actuator Center, University of California, Berkeley, CA 94720 (United States); Huang, J.C. [Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Ke, C.A. [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China)

    2015-08-15

    Highlights: • Performance of the hollow cylindrical near-field electrospinning (HCNFES). • Well-aligned self-assembled PVDF nonwoven fiber fabrics. • Highly durable wearable sensors. • The mechanical characterization of HCNFES piezoelectric NFFs. • The formation of β-form extended-chain crystallites in the PVDF nanofibers. - Abstract: The mechanical characterization of the electrospinning polyvinylidene fluoride (PVDF) nonwoven fiber fabrics (NFFs) doped with multi-walled carbon nanotubes (MWCNTs) was investigated. Piezoelectric composite nanofibers of the PVDF/MWCNTs were directly electrospun by the hollow cylindrical near-field electrospinning (HCNFES) without any post-poling treatment. We have made the HCNFES NFFs consisted of high-orderly arranged nanofiber assemblies for further characterizing the effect of MWCNTs filling PVDF nanofibers. An in situ electrical poling and high uniaxial stretching imparted on the polymer jet during the HCNFES process, which naturally align the dipoles in the PVDF crystals and promote the formation of the polar β-crystalline phase within the fibers. Moreover, the reinforcement of the HCNFES PVDF nanofibers indicated the improvement in mechanical properties and the degree of high oriented extended-chain crystallites through adding adequate contents of MWCNTs. In the case of alignment of the all-trans polymer chains in the vicinity of MWCNTs along the fiber axis, X-ray diffraction (XRD) patterns showed the strongest diffraction peak of the β-crystalline phase. In the comparison of the near-field electrospinning (NFES), the HCNFES nanofibers with smooth surface and smaller diameter can easily form high density structural NFFs. After nano-indentation and tensile strength measurements, the results indicated that the mechanical properties of the HCNFES NFFs are better than the NFES ones. When 16 wt% PVDF solution doped with 0.03 wt% MWCNTs, the results reveal that Young's modulus, hardness, yield stress, yield strain

  1. Transparent Ferroelectric Capacitors on Glass

    Directory of Open Access Journals (Sweden)

    Daniele Sette

    2017-10-01

    Full Text Available We deposited transparent ferroelectric lead zirconate titanate thin films on fused silica and contacted them via Al-doped zinc oxide (AZO transparent electrodes with an interdigitated electrode (IDE design. These layers, together with a TiO2 buffer layer on the fused silica substrate, are highly transparent (>60% in the visible optical range. Fully crystallized Pb(Zr0.52Ti0.48O3 (PZT films are dielectrically functional and exhibit a typical ferroelectric polarization loop with a remanent polarization of 15 μC/cm2. The permittivity value of 650, obtained with IDE AZO electrodes is equivalent to the one measured with Pt electrodes patterned with the same design, which proves the high quality of the developed transparent structures.

  2. Integrated optics on Lithium Niobate for sensing applications

    Science.gov (United States)

    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.

  3. Mechanisms of aging and fatigue in ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Genenko, Yuri A. [Sonderforschungsbereich 595, Institut für Materialwissenschaft, Technische Universität Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt (Germany); Glaum, Julia [Department of Materials Science and Engineering, University of New South Wales, Sydney (Australia); Hoffmann, Michael J. [Institut für keramische Werkstoffe, Haid-und-Neu Str. 7, Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany); Albe, Karsten, E-mail: albe@mm.tu-darmstadt.de [Sonderforschungsbereich 595, Institut für Materialwissenschaft, Technische Universität Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt (Germany)

    2015-02-15

    Highlights: • Experiments on aging and fatigue of bulk ferroelectrics are thoroughly reviewed. • Lead-based PZT and lead-free BNT–BT and KNN materials are covered. • Various fatigue regimes and factors are classified. • Defect associate formation and alignment are analyzed by density functional theory. • Emerging of internal bias field is studied within drift-diffusion approach. - Abstract: A comprehensive review of aging and fatigue phenomena in bulk polycrystalline ferroelectrics is presented. Three material classes are covered, namely the most widely used Pb[Zr{sub 1−x}Ti{sub x}]O{sub 3} (PZT) ceramics and lead-free materials, including those based on bismuth sodium titanate Bi{sub 1/2}Na{sub 1/2}TiO{sub 3} (BNT) and alkali niobate [K{sub x}Na{sub 1−x}]NbO{sub 3} (KNN). Aging is studied in poled and unpoled states both experimentally and theoretically. The variety of different loading regimes for fatigue includes DC electric field, unipolar, sesquipolar and bipolar cycling and all these differently combined with mechanical loading at different frequencies and temperatures. The role of device geometries and electrode materials is addressed and models describing charge migration and defect dipole re-orientation are discussed in the context of recent experimental studies.

  4. Mechanisms of aging and fatigue in ferroelectrics

    International Nuclear Information System (INIS)

    Genenko, Yuri A.; Glaum, Julia; Hoffmann, Michael J.; Albe, Karsten

    2015-01-01

    Highlights: • Experiments on aging and fatigue of bulk ferroelectrics are thoroughly reviewed. • Lead-based PZT and lead-free BNT–BT and KNN materials are covered. • Various fatigue regimes and factors are classified. • Defect associate formation and alignment are analyzed by density functional theory. • Emerging of internal bias field is studied within drift-diffusion approach. - Abstract: A comprehensive review of aging and fatigue phenomena in bulk polycrystalline ferroelectrics is presented. Three material classes are covered, namely the most widely used Pb[Zr 1−x Ti x ]O 3 (PZT) ceramics and lead-free materials, including those based on bismuth sodium titanate Bi 1/2 Na 1/2 TiO 3 (BNT) and alkali niobate [K x Na 1−x ]NbO 3 (KNN). Aging is studied in poled and unpoled states both experimentally and theoretically. The variety of different loading regimes for fatigue includes DC electric field, unipolar, sesquipolar and bipolar cycling and all these differently combined with mechanical loading at different frequencies and temperatures. The role of device geometries and electrode materials is addressed and models describing charge migration and defect dipole re-orientation are discussed in the context of recent experimental studies

  5. Evaluation of domain randomness in periodically poled lithium niobate by diffraction noise measurement.

    Science.gov (United States)

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

    2013-12-16

    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 parasitic noise that can be detrimental to some applications. We demonstrate an accurate but simple method for measuring the RDE in periodically poled lithium niobate. Due to the equivalence between the undepleted harmonic generation spectrum and the diffraction pattern from the QPM grating, we employed linear diffraction measurement which is much simpler than tunable harmonic generation experiments [J. S. Pelc, et al., Opt. Lett.36, 864-866 (2011)]. As a result, we could relate the RDE for the QPM device to the relative noise intensity between the diffraction orders.

  6. A prediction of rate-dependent behaviour in ferroelectric polycrystals

    International Nuclear Information System (INIS)

    Kim, Sang-Joo

    2007-01-01

    Rate-dependent behaviour of a polycrystalline ferroelectric material is predicted based on thermal activation theory and a representative volume element model. First, the behaviour of a ferroelectric single crystal is calculated from a recently proposed three-dimensional free energy model [S.J. Kim, S. Seelecke, Int. J. Solids Struct. 44 (2007) 1196-1209]. Then, from the calculated single crystal responses, poling behaviour of a ferroelectric polycrystal is obtained in three different ways, two representative volume element models and Gaussian integration method. It is found that a dodecahedron representative volume element consisting of 210 crystallites is the best choice among the three methods. Finally, the behaviour of a ferroelectric polycrystal under various electric and stress loads is calculated using the chosen RVE model. The calculated responses are compared qualitatively with experimental observations, and the effects of crystal orientation and polycrystallinity are discussed

  7. Interface and thickness dependent domain switching and stability in Mg doped lithium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Neumayer, Sabine M.; Rodriguez, Brian J., E-mail: gallo@kth.se, E-mail: brian.rodriguez@ucd.ie [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4 (Ireland); Ivanov, Ilia N. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Manzo, Michele; Gallo, Katia, E-mail: gallo@kth.se, E-mail: brian.rodriguez@ucd.ie [Department of Applied Physics, KTH-Royal Institute of Technology, Roslagstullbacken 21, 10691 Stockholm (Sweden); Kholkin, Andrei L. [Department of Physics and CICECO-Aveiro Institute of Materials, 3810-193 Aveiro (Portugal); Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation)

    2015-12-14

    Controlling ferroelectric switching in Mg doped lithium niobate (Mg:LN) is of fundamental importance for optical device and domain wall electronics applications that require precise domain patterns. Stable ferroelectric switching has been previously observed in undoped LN layers above proton exchanged (PE) phases that exhibit reduced polarization, whereas PE layers have been found to inhibit lateral domain growth. Here, Mg doping, which is known to significantly alter ferroelectric switching properties including coercive field and switching currents, is shown to inhibit domain nucleation and stability in Mg:LN above buried PE phases that allow for precise ferroelectric patterning via domain growth control. Furthermore, piezoresponse force microscopy (PFM) and switching spectroscopy PFM reveal that the voltage at which polarization switches from the “up” to the “down” state increases with increasing thickness in pure Mg:LN, whereas the voltage required for stable back switching to the original “up” state does not exhibit this thickness dependence. This behavior is consistent with the presence of an internal frozen defect field. The inhibition of domain nucleation above PE interfaces, observed in this study, is a phenomenon that occurs in Mg:LN but not in undoped samples and is mainly ascribed to a remaining frozen polarization in the PE phase that opposes polarization reversal. This reduced frozen depolarization field in the PE phase also influences the depolarization field of the Mg:LN layer above due to the presence of uncompensated polarization charge at the PE-Mg:LN boundary. These alterations in internal electric fields within the sample cause long-range lattice distortions in Mg:LN via electromechanical coupling, which were corroborated with complimentary Raman measurements.

  8. Electric-field influence on the neutron diffuse scattering near the ferroelectric transition of Sr.sub.0.61./sub.Ba.sub.0.39./sub.Nb.sub.2./sub.O.sub.6./sub.

    Czech Academy of Sciences Publication Activity Database

    Ondrejkovič, Petr; Kempa, Martin; Savinov, Maxim; Bednyakov, Petr; Kulda, J.; Bourges, P.; Dec, J.; Hlinka, Jiří

    2016-01-01

    Roč. 89, 7-8 (2016), s. 808-815 ISSN 0141-1594 R&D Projects: GA ČR GA16-09142S Institutional support: RVO:68378271 Keywords : relaxor ferroelectrics * lead-free * strontium barium niobate * neutron scattering * dielectric spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.060, year: 2016

  9. Tuning characteristics of narrowband THz radiation generated via optical rectification in periodically poled lithium niobate.

    Science.gov (United States)

    Weiss, C; Torosyan, G; Meyn, J P; Wallenstein, R; Beigang, R; Avetisyan, Y

    2001-04-23

    The tuning properties of pulsed narrowband THz radiation generated via optical rectification in periodically poled lithium niobate have been investigated. Using a disk-shaped periodically poled crystal tuning was easily accomplished by rotating the crystal around its axis and observing the generated THz radiation in forward direction. In this way no beam deflection during tuning was observed. The total tuning range extended from 180 GHz up to 830 GHz and was limited by the poling period of 127 microm which determines the maximum THz frequency in forward direction.

  10. Aperture scaling effects with monolithic periodically poled lithium niobate optical parametric oscillators and generators.

    Science.gov (United States)

    Missey, M; Dominic, V; Powers, P; Schepler, K L

    2000-02-15

    We used elliptical beams to demonstrate aperture scaling effects in nanosecond single-grating and multigrating periodically poled lithium niobate (PPLN) monolithic optical parametric oscillators and generators. Increasing the cavity Fresnel number in single-grating crystals broadened both the beam divergence and the spectral bandwidth. Both effects are explained in terms of the phase-matching geometry. These effects are suppressed when a multigrating PPLN crystal is used because the individual gratings provide small effective subapertures. A flood-pumped multigrating optical parametric generator displayed a low output beam divergence and contained 19 pairs of signal and idler frequencies.

  11. Micro- and nanostructuration of lithium niobate; Mikro- und Nanostrukturierung von Lithiumniobat

    Energy Technology Data Exchange (ETDEWEB)

    Hartung, Holger

    2010-04-13

    In the framework of this thesis the application of the ion-beam-enhanced-etching (IBEE) technique for the fabrication of different optical elements, among these photonic crystals, in lithium niobate, was studied. The development of a mask technology fitted to the requirements of the IBEE technique as well as a simulation of the process were performed. Hereby the limitations of the technique in view on minimal structure sizes and structure quality were analyzed. In chapter 1 first the material lithium niobate with its properties and the structuration procedures studied hitherto in the literature is presented. Chapter 2 presents the functionality of the IBEE process and describes the studies on the application of IBEE in lithium niobate performed in the framework of this thesis. In chapter 3 the experimental conditions of all applied processes of the IBEE procedure, the processes used for the mask fabrication, as well all further applied methods and technologies are summarized. Chapter 4 deals with the mask fabrication. The requirements on the masks and the developments necessary for their fulfilment are studied. In chapter 5 the performed simulation of the irradiation, annealing, and etching process is described. This simulation makes the prediciton of the geometry of the components from the process parameters and vice versa the determination of parameters for the reaching of an optimal element geometry possible. In chapter 6 the application of the technique for the fabrication of photonic-crystal membranes and their optical characterization is described. Chapter 7 shows the fabrication of different waveguide and diffractive elements in lithium niobate by means of IBEE.

  12. Catalytic oxidation of soot over alkaline niobates

    International Nuclear Information System (INIS)

    Pecchi, G.; Cabrera, B.; Buljan, A.; Delgado, E.J.; Gordon, A.L.; Jimenez, R.

    2013-01-01

    Highlights: ► No previous reported studies about alkaline niobates as catalysts for soot oxidation. ► NaNbO 3 and KNbO 3 perovskite-type oxides show lower activation energy than other lanthanoid perovskite-type oxides. ► The alkaline niobate does not show deactivation by metal loss. - Abstract: The lack of studies in the current literature about the assessment of alkaline niobates as catalysts for soot oxidation has motivated this research. In this study, the synthesis, characterization and assessment of alkaline metal niobates as catalysts for soot combustion are reported. The solids MNbO 3 (M = Li, Na, K, Rb) are synthesized by a citrate method, calcined at 450 °C, 550 °C, 650 °C, 750 °C, and characterized by AAS, N 2 adsorption, XRD, O 2 -TPD, FTIR and SEM. All the alkaline niobates show catalytic activity for soot combustion, and the activity depends basically on the nature of the alkaline metal and the calcination temperature. The highest catalytic activity, expressed as the temperature at which combustion of carbon black occurs at the maximum rate, is shown by KNbO 3 calcined at 650 °C. At this calcination temperature, the catalytic activity follows an order dependent on the atomic number, namely: KNbO 3 > NaNbO 3 > LiNbO 3 . The RbNbO 3 solid do not follow this trend presumably due to the perovskite structure was not reached. The highest catalytic activity shown by of KNbO 3 , despite the lower apparent activation energy of NaNbO 3 , stress the importance of the metal nature and suggests the hypothesis that K + ions are the active sites for soot combustion. It must be pointed out that alkaline niobate subjected to consecutive soot combustion cycles does not show deactivation by metal loss, due to the stabilization of the alkaline metal inside the perovskite structure.

  13. An Automated Ab Initio Framework for Identifying New Ferroelectrics

    Science.gov (United States)

    Smidt, Tess; Reyes-Lillo, Sebastian E.; Jain, Anubhav; Neaton, Jeffrey B.

    Ferroelectric materials have a wide-range of technological applications including non-volatile RAM and optoelectronics. In this work, we present an automated first-principles search for ferroelectrics. We integrate density functional theory, crystal structure databases, symmetry tools, workflow software, and a custom analysis toolkit to build a library of known and proposed ferroelectrics. We screen thousands of candidates using symmetry relations between nonpolar and polar structure pairs. We use two search strategies 1) polar-nonpolar pairs with the same composition and 2) polar-nonpolar structure type pairs. Results are automatically parsed, stored in a database, and accessible via a web interface showing distortion animations and plots of polarization and total energy as a function of distortion. We benchmark our results against experimental data, present new ferroelectric candidates found through our search, and discuss future work on expanding this search methodology to other material classes such as anti-ferroelectrics and multiferroics.

  14. Ferroelectrics under the Synchrotron Light: A Review

    Science.gov (United States)

    Fuentes-Cobas, Luis E.; Montero-Cabrera, María E.; Pardo, Lorena; Fuentes-Montero, Luis

    2015-01-01

    Currently, an intensive search for high-performance lead-free ferroelectric materials is taking place. ABO3 perovskites (A = Ba, Bi, Ca, K and Na; B = Fe, Nb, Ti, and Zr) appear as promising candidates. Understanding the structure–function relationship is mandatory, and, in this field, the roles of long- and short-range crystal orders and interactions are decisive. In this review, recent advances in the global and local characterization of ferroelectric materials by synchrotron light diffraction, scattering and absorption are analyzed. Single- and poly-crystal synchrotron diffraction studies allow high-resolution investigations regarding the long-range average position of ions and subtle global symmetry break-downs. Ferroelectric materials, under the action of electric fields, undergo crystal symmetry, crystallite/domain orientation distribution and strain condition transformations. Methodological aspects of monitoring these processes are discussed. Two-dimensional diffraction clarify larger scale ordering: polycrystal texture is measured from the intensities distribution along the Debye rings. Local order is investigated by diffuse scattering (DS) and X-ray absorption fine structure (XAFS) experiments. DS provides information about thermal, chemical and displacive low-dimensional disorders. XAFS investigation of ferroelectrics reveals local B-cation off-centering and oxidation state. This technique has the advantage of being element-selective. Representative reports of the mentioned studies are described. PMID:28787814

  15. Ferroelectrics under the Synchrotron Light: A Review

    Directory of Open Access Journals (Sweden)

    Luis E. Fuentes-Cobas

    2015-12-01

    Full Text Available Currently, an intensive search for high-performance lead-free ferroelectric materials is taking place. ABO3 perovskites (A = Ba, Bi, Ca, K and Na; B = Fe, Nb, Ti, and Zr appear as promising candidates. Understanding the structure–function relationship is mandatory, and, in this field, the roles of long- and short-range crystal orders and interactions are decisive. In this review, recent advances in the global and local characterization of ferroelectric materials by synchrotron light diffraction, scattering and absorption are analyzed. Single- and poly-crystal synchrotron diffraction studies allow high-resolution investigations regarding the long-range average position of ions and subtle global symmetry break-downs. Ferroelectric materials, under the action of electric fields, undergo crystal symmetry, crystallite/domain orientation distribution and strain condition transformations. Methodological aspects of monitoring these processes are discussed. Two-dimensional diffraction clarify larger scale ordering: polycrystal texture is measured from the intensities distribution along the Debye rings. Local order is investigated by diffuse scattering (DS and X-ray absorption fine structure (XAFS experiments. DS provides information about thermal, chemical and displacive low-dimensional disorders. XAFS investigation of ferroelectrics reveals local B-cation off-centering and oxidation state. This technique has the advantage of being element-selective. Representative reports of the mentioned studies are described.

  16. Dimensional scaling of perovskite ferroelectric thin films

    Science.gov (United States)

    Keech, Ryan R.

    Dimensional size reduction has been the cornerstone of the exponential improvement in silicon based logic devices for decades. However, fundamental limits in the device physics were reached ˜2003, halting further reductions in clock speed without significant penalties in power consumption. This has motivated the research into next generation transistors and switching devices to reinstate the scaling laws for clock speed. This dissertation aims to support the scaling of devices that are based on ferroelectricity and piezoelectricity and to provide a roadmap for the corresponding materials performance. First, a scalable growth process to obtain highly {001}-oriented lead magnesium niobate - lead titanate (PMN-PT) thin films was developed, motivated by the high piezoelectric responses observed in bulk single crystals. It was found that deposition of a 2-3 nm thick PbO buffer layer on {111} Pt thin film bottom electrodes, prior to chemical solution deposition of PMN-PT reduces the driving force for Pb diffusion from the PMN-PT to the bottom electrode, and facilitates nucleation of {001}-oriented perovskite grains. Energy dispersive spectroscopy demonstrated that up to 10% of the Pb from a PMN-PT precursor solution may diffuse into the bottom electrode. PMN-PT grains with a mixed {101}/{111} orientation in a matrix of Pb-deficient pyrochlore phase were then promoted near the interface. When this is prevented, phase pure films with {001} orientation with Lotgering factors of 0.98-1.0, can be achieved. The resulting films of only 300 nm in thickness exhibit longitudinal effective d33,f coefficients of ˜90 pm/V and strain values of ˜1% prior to breakdown. 300 nm thick epitaxial and polycrystalline lead magnesium niobate - lead titanate (70PMN-30PT) blanket thin films were studied for the relative contributions to property thickness dependence from interfacial and grain boundary low permittivity layers. Epitaxial PMN-PT films were grown on SrRuO 3 /(001)SrTiO3, while

  17. Light-Activated Gigahertz Ferroelectric Domain Dynamics

    Science.gov (United States)

    Akamatsu, Hirofumi; Yuan, Yakun; Stoica, Vladimir A.; Stone, Greg; Yang, Tiannan; Hong, Zijian; Lei, Shiming; Zhu, Yi; Haislmaier, Ryan C.; Freeland, John W.; Chen, Long-Qing; Wen, Haidan; Gopalan, Venkatraman

    2018-03-01

    Using time- and spatially resolved hard x-ray diffraction microscopy, the striking structural and electrical dynamics upon optical excitation of a single crystal of BaTiO3 are simultaneously captured on subnanoseconds and nanoscale within individual ferroelectric domains and across walls. A large emergent photoinduced electric field of up to 20 ×106 V /m is discovered in a surface layer of the crystal, which then drives polarization and lattice dynamics that are dramatically distinct in a surface layer versus bulk regions. A dynamical phase-field modeling method is developed that reveals the microscopic origin of these dynamics, leading to gigahertz polarization and elastic waves traveling in the crystal with sonic speeds and spatially varying frequencies. The advances in spatiotemporal imaging and dynamical modeling tools open up opportunities for disentangling ultrafast processes in complex mesoscale structures such as ferroelectric domains.

  18. Study of lead free ferroelectrics using overlay technique on thick film microstrip ring resonator

    Directory of Open Access Journals (Sweden)

    Shridhar N. Mathad

    2016-03-01

    Full Text Available The lead free ferroelectrics, strontium barium niobates, were synthesized via the low cost solid state reaction method and their fritless thick films were fabricated by screen printing technique on alumina substrate. The X band response (complex permittivity at very high frequencies of Ag thick film microstrip ring resonator perturbed with strontium barium niobates (SrxBa1-xNb2O6 in form of bulk and thick film was measured. A new approach for determination of complex permittivity (ε′ and ε′′ in the frequency range 8–12 GHz, using perturbation of Ag thick film microstrip ring resonator (MSRR, was applied for both bulk and thick film of strontium barium niobates (SrxBa1-xNb2O6. The microwave conductivity of the bulk and thick film lie in the range from 1.779 S/cm to 2.874 S/cm and 1.364 S/cm to 2.296 S/cm, respectively. The penetration depth of microwave in strontium barium niobates is also reported.

  19. Ferroelectric properties of tungsten bronze morphotropic phase boundary systems

    International Nuclear Information System (INIS)

    Oliver, J.R.; Neurgaonkar, R.R.; Cross, L.E.; Pennsylvania State Univ., University Park, PA

    1989-01-01

    Tungsten bronze ferroelectrics which have a morphotropic phase boundary (MPB) can have a number or enhanced dielectric, piezoelectric, and electrooptic properties compared to more conventional ferroelectric materials. The structural and ferroelectric properties of several MPB bronze systems are presented, including data from sintered and hot-pressed ceramics, epitaxial thin films, and bulk single crystals. Included among these are three systems which had not been previously identified as morphotropic. The potential advantages and limitations of these MPB systems are discussed, along with considerations of the appropriate growth methods for their possible utilization in optical, piezoelectric, or pyroelectric device applications

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

    Energy Technology Data Exchange (ETDEWEB)

    Lengyel, K.; Péter, Á.; Kovács, L.; Corradi, G.; Dravecz, G.; Hajdara, I.; Szaller, Zs.; Polgár, K. [Wigner Research Centre for Physics, Hungarian Academy of Sciences, 1121 Budapest, Konkoly-Thege M. út 29-33 (Hungary); Pálfalvi, L.; Unferdorben, M. [Institute of Physics, University of Pécs, 7624 Pécs, Ifjúság útja 6 (Hungary); Hebling, J. [Institute of Physics, University of Pécs, 7624 Pécs, Ifjúság útja 6 (Hungary); MTA-PTE High Field Terahertz Research Group, 7624 Pécs (Hungary)

    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

  1. Effect of Ion Irradiation in Cadmium Niobate Pyrochlores

    International Nuclear Information System (INIS)

    Jiang, Weilin; Weber, William J.; Thevuthasan, Suntharampillai; Boatner, Lynn A.

    2003-01-01

    Irradiation experiments have been performed for cadmium niobate pyrochlore (CdNb2O) single crystals at both 150 and 300 K using 1.0 MeV Au ions over fluences ranging from 0.01 to 0.10 ions/nm. In-situ 3.0 MeV He Rutherford backscattering spectrometry along the -axial channeling direction (RBS/C) has been applied to study the damage states ranging from small defect concentrations to a fully amorphous state. Results show that the crystal can be readily amorphized under the irradiation conditions. Room-temperature recovery of the defects produced at 150 K has been observed, while the defects produced at 300 K are thermally stable at room temperature. Results also indicate that the RBS/C analysis used in this study induced negligible damage in the near-surface regime. In addition, irradiation at and below room temperature using He and C3 ions leads to surface exfoliation at the corresponding damage peaks

  2. Recent Achievements on Photovoltaic Optoelectronic Tweezers Based on Lithium Niobate

    Directory of Open Access Journals (Sweden)

    Angel García-Cabañes

    2018-01-01

    Full Text Available This review presents an up-dated summary of the fundamentals and applications of optoelectronic photovoltaic tweezers for trapping and manipulation of nano-objects on the surface of lithium niobate crystals. It extends the contents of previous reviews to cover new topics and developments which have emerged in recent years and are marking the trends for future research. Regarding the theoretical description of photovoltaic tweezers, detailed simulations of the electrophoretic and dielectrophoretic forces acting on different crystal configurations are discussed in relation to the structure of the obtained trapping patterns. As for the experimental work, we will pay attention to the manipulation and patterning of micro-and nanoparticles that has experimented an outstanding progress and relevant applications have been reported. An additional focus is now laid on recent work about micro-droplets, which is a central topic in microfluidics and optofluidics. New developments in biology and biomedicine also constitute a relevant part of the review. Finally, some topics partially related with photovoltaic tweezers and a discussion on future prospects and challenges are included.

  3. Synthesis and characterization of bismuth zinc niobate pyrochlore nanopowders

    Directory of Open Access Journals (Sweden)

    Sonia Maria Zanetti

    2007-09-01

    Full Text Available Bismuth zinc niobate pyrochlores Bi1.5ZnNb1.5O7 (alpha-BZN, and Bi2(Zn1/3Nb2/32O 7 (beta-BZN have been synthesized by chemical method based on the polymeric precursors. The pyrochlore phase was investigated by differential scanning calorimetry, infrared spectroscopy, and X ray diffraction. Powder and sintered pellets morphology was examined by scanning electron microscopy. The study of alpha-BZN phase formation reveals that, at 500 °C, the pyrochlore phase was already present while a single-phased nanopowder was obtained after calcination at 700 °C. The crystallization mechanism of the beta-BZN is quite different, occurring through the crystallization of alpha-BZN and BiNbO4 intermediary phases. Both compositions yielded soft agglomerated powders. alpha-BZN pellets, sintered at 800 °C for 2 hours, presented a relative density of 97.3% while those of beta-BZN, sintered at 900 °C for 2 hours, reached only 91.8%. Dielectric constant and dielectric loss, measured at 1 MHz, were 150 and 4 x/10-4 for a-BZN, and 97 and 8 x 10-4 for beta-BZN.

  4. PbBr3 Perovskite Crystals

    KAUST Repository

    Wei, Tzu-Chiao

    2018-01-31

    Researchers have recently revealed that hybrid lead halide perovskites exhibit ferroelectricity, which is often associated with other physical characteristics, such as a large nonlinear optical response. In this work, the nonlinear optical properties of single crystal inorganic–organic hybrid perovskite CH3NH3PbBr3 are studied. By exciting the material with a 1044 nm laser, strong two-photon absorption-induced photoluminescence in the green spectral region is observed. Using the transmission open-aperture Z-scan technique, the values of the two-photon absorption coefficient are observed to be 8.5 cm GW−1, which is much higher than that of standard two-photon absorbing materials that are industrially used in nonlinear optical applications, such as lithium niobate (LiNbO3), LiTaO3, KTiOPO4, and KH2PO4. Such a strong two-photon absorption effect in CH3NH3PbBr3 can be used to modulate the spectral and spatial profiles of laser pulses, as well as to reduce noise, and can be used to strongly control the intensity of incident light. In this study, the superior optical limiting, pulse reshaping, and stabilization properties of CH3NH3PbBr3 are demonstrated, opening new applications for perovskites in nonlinear optics.

  5. Ferroelectric switching of elastin

    Science.gov (United States)

    Liu, Yuanming; Cai, Hong-Ling; Zelisko, Matthew; Wang, Yunjie; Sun, Jinglan; Yan, Fei; Ma, Feiyue; Wang, Peiqi; Chen, Qian Nataly; Zheng, Hairong; Meng, Xiangjian; Sharma, Pradeep; Zhang, Yanhang; Li, Jiangyu

    2014-01-01

    Ferroelectricity has long been speculated to have important biological functions, although its very existence in biology has never been firmly established. Here, we present compelling evidence that elastin, the key ECM protein found in connective tissues, is ferroelectric, and we elucidate the molecular mechanism of its switching. Nanoscale piezoresponse force microscopy and macroscopic pyroelectric measurements both show that elastin retains ferroelectricity at 473 K, with polarization on the order of 1 μC/cm2, whereas coarse-grained molecular dynamics simulations predict similar polarization with a Curie temperature of 580 K, which is higher than most synthetic molecular ferroelectrics. The polarization of elastin is found to be intrinsic in tropoelastin at the monomer level, analogous to the unit cell level polarization in classical perovskite ferroelectrics, and it switches via thermally activated cooperative rotation of dipoles. Our study sheds light onto a long-standing question on ferroelectric switching in biology and establishes ferroelectricity as an important biophysical property of proteins. This is a critical first step toward resolving its physiological significance and pathological implications. PMID:24958890

  6. III-Nitrides growth and AlGaN/GaN heterostructures on ferroelectric materials

    International Nuclear Information System (INIS)

    Lee, Kyoung-Keun; Namkoong, Gon; Madison, Shannon M.; Ralph, Stephen E.; Doolittle, W. Alan; Losurdo, Maria; Bruno, Giovanni; Cho, Hyung Koun

    2007-01-01

    The growth of III-nitrides on the ferroelectric materials lithium niobate (LN) and lithium tantalate (LT) via molecular beam epitaxy (MBE) using rf plasma source has been investigated. We have found that gallium nitride (GaN) epitaxial layers have a crystalline relationship with lithium niobate (tantalate) as follows: (0 0 0 1) GaN || (0 0 0 1) LN (LT) with [10-10] GaN || [11-20] LN (LT). The surface stability of LN and LT substrates has been monitored by in situ spectroscopic ellipsometry in the vacuum chamber. Three different temperature zones have been discerned; surface degas and loss of OH group (100-350 deg. C); surface segregation/accumulation of Li and O-species (400-700 deg. C); surface evaporation of O-species and Li desorption (over 750 deg. C). However, LT shows only surface degassing in the range of 100-800 deg. C. Therefore, congruent LN substrates were chemically unstable at the growth temperature of 550-650 deg. C, and therefore developed an additional phase of Li-deficient lithium niobate (LiNb 3 O 8 ) along with lithium niobate (LiNbO 3 ), confirmed by X-ray diffraction. On the other hand, LT showed better chemical stability at these temperatures, with no additional phase development. The structural quality of GaN epitaxial layers has shown slight improvement on LT substrates over LN substrates, according to X-ray diffraction. Herein, we demonstrate AlGaN/GaN heterostructure devices on ferroelectric materials that will allow future development of multifunctional electrical and optical applications

  7. III-Nitrides growth and AlGaN/GaN heterostructures on ferroelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyoung-Keun [Georgia Institute of Technology, School of Electrical and Computer Engineering, 777 Atlantic Dr., Atlanta, GA 30332 (United States); Namkoong, Gon [Old Dominion University, Department of Electrical and Computer Engineering, Norfolk, VA 23529 (United States); Madison, Shannon M. [Georgia Institute of Technology, School of Electrical and Computer Engineering, 777 Atlantic Dr., Atlanta, GA 30332 (United States); Ralph, Stephen E. [Georgia Institute of Technology, School of Electrical and Computer Engineering, 777 Atlantic Dr., Atlanta, GA 30332 (United States); Doolittle, W. Alan [Georgia Institute of Technology, School of Electrical and Computer Engineering, 777 Atlantic Dr., Atlanta, GA 30332 (United States)]. E-mail: alan.doolittle@ece.gatech.edu; Losurdo, Maria [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, Department of Chemistry, University of Bari, via Orabona, 4 70126 Bari (Italy); Bruno, Giovanni [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, Department of Chemistry, University of Bari, via Orabona, 4 70126 Bari (Italy); Cho, Hyung Koun [Department of Materials Science and Engineering, Sung Kyun Kwan University, Suwon 440-746 (Korea, Republic of)

    2007-06-15

    The growth of III-nitrides on the ferroelectric materials lithium niobate (LN) and lithium tantalate (LT) via molecular beam epitaxy (MBE) using rf plasma source has been investigated. We have found that gallium nitride (GaN) epitaxial layers have a crystalline relationship with lithium niobate (tantalate) as follows: (0 0 0 1) GaN || (0 0 0 1) LN (LT) with [10-10] GaN || [11-20] LN (LT). The surface stability of LN and LT substrates has been monitored by in situ spectroscopic ellipsometry in the vacuum chamber. Three different temperature zones have been discerned; surface degas and loss of OH group (100-350 deg. C); surface segregation/accumulation of Li and O-species (400-700 deg. C); surface evaporation of O-species and Li desorption (over 750 deg. C). However, LT shows only surface degassing in the range of 100-800 deg. C. Therefore, congruent LN substrates were chemically unstable at the growth temperature of 550-650 deg. C, and therefore developed an additional phase of Li-deficient lithium niobate (LiNb{sub 3}O{sub 8}) along with lithium niobate (LiNbO{sub 3}), confirmed by X-ray diffraction. On the other hand, LT showed better chemical stability at these temperatures, with no additional phase development. The structural quality of GaN epitaxial layers has shown slight improvement on LT substrates over LN substrates, according to X-ray diffraction. Herein, we demonstrate AlGaN/GaN heterostructure devices on ferroelectric materials that will allow future development of multifunctional electrical and optical applications.

  8. Experimental and theoretical investigation of lattice defect structures in a series of Zn, Fe-doped nonstoichiometric lithium niobate

    International Nuclear Information System (INIS)

    Guo Fengyun; Lue Qiang; Sun Liang; Li Hongtao; Zhen Xihe; Xu Yuheng; Zhao Liancheng

    2006-01-01

    A series of the double doped lithium niobate (LiNbO 3 , LN) single crystals had been grown by Czochralski method. The Curie temperatures of various concentrations doped or [Li]/[Nb] ratio LN crystals measured by differential thermal analysis (DTA) were discussed to investigate their defect structures with Safaryan et al. new approach about LN lattice defect structure using Curie temperatures calculated. Infrared transmission spectra of various concentrations doped were used to compare the investigation above. The results show that the lithium vacancy model is the more probable to describe the lattice defect structure of the doped LN single crystal

  9. Ferroelectricity at the nanoscale basics and applications

    CERN Document Server

    Fridkin, Vladimir

    2014-01-01

    This book examines a wide range of ferroelectric materials. It explains the theoretical background of ultrathin ferroelectric films,  presents applications of ferroelectric materials, and displays the mechanism of switching of nanosized ferroelectric films.

  10. Growth of potassium niobate micro-hexagonal tablets with monoclinic phase and its excellent piezoelectric property

    Science.gov (United States)

    Chen, Zhong; Huang, Jingyun; Wang, Ye; Yang, Yefeng; Wu, Yongjun; Ye, Zhizhen

    2012-09-01

    Potassium niobate micro-hexagonal tablets were synthesized through hydrothermal reaction with KOH, H2O and Nb2O5 as source materials by using a polycrystalline Al2O3 as substrate. X-ray diffraction, Raman spectra and selected area electron diffraction analysis results indicated that the tablets exhibit monoclinic phase structure and are highly crystallized. Meanwhile, piezoelectric property of the micro-hexagonal tablets was investigated. The as-synthesized tablets exhibit excellent piezoactivities in the experiments, and an effective piezoelectric coefficient of around 80 pm/V was obtained. The tablets have huge potential applications in micro/nano-integrated piezoelectric and optical devices.

  11. Diffusion of iron in lithium niobate: a secondary ion mass spectrometry study

    Energy Technology Data Exchange (ETDEWEB)

    Ciampolillo, M.V.; Argiolas, N.; Zaltron, A.; Bazzan, M.; Sada, C. [University of Padova, Physics Department (Italy); CNISM, Padova (Italy)

    2011-10-15

    Iron-doped X-cut lithium niobate crystals were prepared by means of thermal diffusion from thin film varying in a systematic way the process parameters such as temperature and diffusion duration. Secondary Ion Mass Spectrometry was exploited to characterize the iron in-depth profiles. The evolution of the composition of the Fe thin film in the range between 600 C and 800 C was studied, and the diffusion coefficient at different temperatures in the range between 900 C and 1050 C and the activation energy of the diffusion process were estimated. (orig.)

  12. Rare earth niobate coordination polymers

    Science.gov (United States)

    Muniz, Collin N.; Patel, Hiral; Fast, Dylan B.; Rohwer, Lauren E. S.; Reinheimer, Eric W.; Dolgos, Michelle; Graham, Matt W.; Nyman, May

    2018-03-01

    Rare-earth (RE) coordination polymers are infinitely tailorable to yield luminescent materials for various applications. Here we described the synthesis of a heterometallic rare-earth coordination compound ((CH3)2SO)3(RE)NbO(C2O4)3((CH3)2SO) = dimethylsulfoxide, DMSO, (C2O2= oxalate), (RE=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb). The structure was obtained from single crystal X-ray diffraction of the La analogue. The Nb˭O and DMSO terminal-bonding character guides assembly of an open framework structure with noncentrosymmetric RE-coordination geometry, and large spacing between the RE centers. A second structure was observed by PXRD for the smaller rare earths (Dy, Ho, Er, Yb); this structure has not yet been determined. The materials were further characterized using FTIR, and photoluminescence measurements. Characteristic excitation and emission transitions were observed for RE = Nd, Sm, Eu, and Tb. Quantum yield (QY) measurements were performed by exciting Eu and Tb analoges at 394 nm (QY 66%) and 464 nm (QY 71%) for Eu; and 370 nm (QY=40%) for Tb. We attribute the high QY and bright luminescence to two main structure-function properties of the system; namely the absence of water in the structure, and absence of concentration quenching.

  13. Switching kinetics of a relaxor ferroelectric Sr0.75Ba0.25Nb2O6 observed by the second harmonic generation method

    International Nuclear Information System (INIS)

    Volk, Tatyana; Isakov, Dmitry; Belsley, Michael Scott; Ivleva, Lyudmila

    2009-01-01

    In this work we present a study of the ferroelectric switching kinetic process in strontium-barium niobate (SBN). The kinetics of polarization deduced from the dynamics of the diffuse second harmonic generation is in good qualitative agreement with thekinetics observed by more traditional polarization methods. Our work highlights the specific characteristics of polarization reversal in SBN, which is fundamentally different from that which occurs in model ferroelectrics. The presented optical measurements of the polarization processes provide several experimental advantages over traditional electrical measurements. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Growth and characterization of Pb(Lu{sub 1/2}Nb{sub 1/2})O{sub 3}-Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} ternary piezo-/ferroelectric crystals

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); College of Physics and Energy, Fujian Normal University, Fuzhou, Fujian 350117 (China); He, Chao [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Yang, Xiaoming [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); College of Physics and Energy, Fujian Normal University, Fuzhou, Fujian 350117 (China); Li, Xiuzhi; Wang, Zujian [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Huang, Zhigao; Lai, Fachun [College of Physics and Energy, Fujian Normal University, Fuzhou, Fujian 350117 (China); Long, Xifa, E-mail: lxf@fjirsm.ac.cn [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

    2016-08-05

    Piezo-/ferroelectric crystals of Pb(Lu{sub 1/2}Nb{sub 1/2})O{sub 3}-Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} ternary solid solution system with high Curie temperature, in the vicinity of morphotropic phase boundary (MPB) region, are grown by the top-seeded solution growth (TSSG) method for the first time. The compositions and structures of the crystals are analyzed, all the structures are found to have pure perovskite structure using X-ray diffraction analysis. Di-/piezo-/ferroelectric properties of the crystals are also characterized systematically. The Curie temperature T{sub c} and coercive field E{sub c}, increase gradually with increasing PbTiO{sub 3} content. In particular, the crystal with composition 0.34PLN-0.31PMN-0.35PT possesses excellent electric properties including the Curie temperature, the rhombohedral–tetragonal phase transition temperature, the piezoelectric coefficient, the remnant polarization and the coercive field, which are T{sub c} = 228 °C, T{sub RT} = 156 °C, d{sub 33} = 2092 pC N{sup −1}, Pr = 35.5 μC cm{sup −2} and E{sub c} = 8.1 kV cm{sup −1}, respectively, making it a promising material for transducers or detectors in a wide temperature range. - Highlights: • PLN-PMN-PT Piezo-/ferroelectric crystals are grown by TSSG method. • The Curie temperature and coercive field increase gradually with increasing PT. • The crystal of 0.34PLN-0.31PMN-0.35PT possesses excellent electric properties.

  15. Quantum mechanical studies of complex ferroelectric perovskites

    Science.gov (United States)

    Ramer, Nicholas John

    In many electronic device applications, there is a need to interconvert electrical energy and other types of energy. Ferroelectric materials, which possess a voltage-dependent polarization, can enable this energy conversion process. Because of the broad interest in ferroelectric materials for these devices, there is a critical research effort, both experimental and theoretical, to understand these materials and aid in the development of materials with improved properties. This thesis presents detailed quantum mechanical investigations of the behavior of a complex ferroelectric perovskite under applied stress. In particular, we have chosen to study the solid solution PbZr1-xTix O3 (PZT). Since the study of ferroelectricity involves understanding both its structural and electronic signatures in materials, it has necessitated the development of a novel theoretical technique which improves the accuracy of the pseudopotentials used in our density functional theory calculations as well as a new method for constructing three-dimensional atomistic responses to small amounts of external stress. To examine the material's behavior under larger amounts of stress, we have studied the behavior of a composition of PZT lying near a structural phase boundary. On either side of the phase boundary, the material is characterized by a different polarization direction and may easily be switched between phases by applying external stress. In addition to stress-induced phase transitions, most ferroelectric materials also have composition dependent phase boundaries. Since different compositions of PZT would require increased computational effort, we have formulated an improved virtual crystal approach that makes tractable the study of the entire composition range. Using this method, we have been able to show for the first time via first-principles calculations, a composition dependent phase transition in a ferroelectric material. This thesis has accomplished three important goals: new

  16. Atomic resolution imaging of ferroelectric domains

    International Nuclear Information System (INIS)

    Bursill, L.A.

    1997-01-01

    Electron optical principles involved in obtaining atomic resolution images of ferroelectric domains are reviewed, including the methods available to obtain meaningful interpretation and analysis of the image detail in terms of the atomic structures. Recent work is concerned with establishing the relationship between the essentially static chemical nanodomains and the spatial and temporal fluctuations of the nanoscale polar domains present in the relaxor class of materials, including lead scandium tantalate (PST) and lead magnesium niobate (PMN). Correct interpretation of the images required use of Next Nearest Neighbour Ising model simulations for the chemical domain textures upon which we must superimpose the polar domain textures; an introduction to this work is presented. A thorough analysis of the atomic scale chemical inhomogeneities, based upon the HRTEM results, has lead to an improved formulation of the theory of the dielectric response of PMN and PST, which is capable to predict the observed temperature and frequency dependence. HRTEM may be combined with solid state and statistical physics principles to provide a deeper understanding of structure/property relationships. 15 refs., 6 figs

  17. Analysis of Waveguides on Lithium Niobate Thin Films

    Directory of Open Access Journals (Sweden)

    Yiwen Wang

    2018-04-01

    Full Text Available Waveguides formed by etching, proton-exchange (PE, and strip-loaded on single-crystal lithium niobate (LN thin film were designed and simulated by a full-vectorial finite difference method. The single-mode condition, optical power distribution, and bending loss of these kinds of waveguides were studied and compared systematically. For the PE waveguide, the optical power distributed in LN layer had negligible change with the increase of PE thickness. For the strip-loaded waveguide, the relationships between optical power distribution in LN layer and waveguide thickness were different for quasi-TE (q-TE and quasi-TM (q-TM modes. The bending loss would decrease with the increase of bending radius. There was a bending loss caused by the electromagnetic field leakage when the neff of q-TM waveguide was smaller than that of nearby TE planar waveguide. LN ridge waveguides possessed a low bending loss even at a relatively small bending radius. This study is helpful for the understanding of waveguide structures as well as for the optimization and the fabrication of high-density integrated optical components.

  18. Magnetophotorefractive effect and interference filters in lithium niobate

    International Nuclear Information System (INIS)

    Dam-Hansen, C.

    1996-03-01

    This thesis deals with the fundamental photorefractive and photovoltaic properties of iron-doped lithium niobate crystals. Experimental observations of a strong magnetic field effect on the energy coupling and grating formation in a vectorial interaction scheme are presented. To the author's knowledge these are the first reported results in the field. It is shown that an enhancement of the diffraction efficiency of 60% is possible by applying even a moderate magnetic field of 0.23 T. A new theoretical model of the magnetophotorefractive effect in the vectorial interaction scheme is presented. It describes the space-charge field formation, two-wave mixing and grating formation under the influence of an externally applied magnetic field. Good agreement with the experimental results and the first measurement of nondiagonal components of the magnetophotovoltaic tensor are reported. A theoretical model for the temperature properties of photorefractive interference filters with subangstrom bandwidths are presented and compared favourably with experimental investigations. A novel method for determining the spectral response of these filters from a combined thermal and angular response measurements is described. (au) 9 tabs., 30 ills., 84 refs

  19. Concurrent transition of ferroelectric and magnetic ordering near room temperature.

    Science.gov (United States)

    Ko, Kyung-Tae; Jung, Min Hwa; He, Qing; Lee, Jin Hong; Woo, Chang Su; Chu, Kanghyun; Seidel, Jan; Jeon, Byung-Gu; Oh, Yoon Seok; Kim, Kee Hoon; Liang, Wen-I; Chen, Hsiang-Jung; Chu, Ying-Hao; Jeong, Yoon Hee; Ramesh, Ramamoorthy; Park, Jae-Hoon; Yang, Chan-Ho

    2011-11-29

    Strong spin-lattice coupling in condensed matter gives rise to intriguing physical phenomena such as colossal magnetoresistance and giant magnetoelectric effects. The phenomenological hallmark of such a strong spin-lattice coupling is the manifestation of a large anomaly in the crystal structure at the magnetic transition temperature. Here we report that the magnetic Néel temperature of the multiferroic compound BiFeO(3) is suppressed to around room temperature by heteroepitaxial misfit strain. Remarkably, the ferroelectric state undergoes a first-order transition to another ferroelectric state simultaneously with the magnetic transition temperature. Our findings provide a unique example of a concurrent magnetic and ferroelectric transition at the same temperature among proper ferroelectrics, taking a step toward room temperature magnetoelectric applications.

  20. A hybrid ferroelectric-flash memory cells

    Science.gov (United States)

    Park, Jae Hyo; Byun, Chang Woo; Seok, Ki Hwan; Kim, Hyung Yoon; Chae, Hee Jae; Lee, Sol Kyu; Son, Se Wan; Ahn, Donghwan; Joo, Seung Ki

    2014-09-01

    A ferroelectric-flash (F-flash) memory cells having a metal-ferroelectric-nitride-oxynitride-silicon structure are demonstrated, and the ferroelectric materials were perovskite-dominated Pb(Zr,Ti)O3 (PZT) crystallized by Pt gate electrode. The PZT thin-film as a blocking layer improves electrical and memorial performance where programming and erasing mechanism are different from the metal-ferroelectric-insulator-semiconductor device or the conventional silicon-oxide-nitride-oxide-silicon device. F-flash cells exhibit not only the excellent electrical transistor performance, having 442.7 cm2 V-1 s-1 of field-effect mobility, 190 mV dec-1 of substhreshold slope, and 8 × 105 on/off drain current ratio, but also a high reliable memory characteristics, having a large memory window (6.5 V), low-operating voltage (0 to -5 V), faster P/E switching speed (50/500 μs), long retention time (>10 years), and excellent fatigue P/E cycle (>105) due to the boosting effect, amplification effect, and energy band distortion of nitride from the large polarization. All these characteristics correspond to the best performances among conventional flash cells reported so far.

  1. Dual-wavelength green laser with a 4.5 THz frequency difference based on self-frequency- doubling in Nd3+ -doped aperiodically poled lithium niobate.

    Science.gov (United States)

    Maestre, H; Torregrosa, A J; Fernández-Pousa, C R; Rico, M L; Capmany, J

    2008-05-01

    We report a dual-wavelength continuous-wave laser at 542.4 and 546.8 nm based on an Nd(3+)-doped aperiodically poled lithium niobate crystal. Two fundamental infrared (IR) wavelengths at 1084.8 and 1093.6 nm are simultaneously oscillated and self-frequency-doubled to green. The aperiodic domain distribution patterned in the crystal allows for quasi-phase matched self-frequency-doubling of both IR fundamentals while avoiding their sum-frequency mixing.

  2. Growth of Ca, Zr co-doped BaTiO3 lead-free ferroelectric single crystal and its room-temperature piezoelectricity

    Directory of Open Access Journals (Sweden)

    Donglin Liu

    2017-09-01

    Full Text Available Lead-free Ca, Zr co-doped BaTiO3 (BCZT single crystal with a dimension up to 2mm×2mm×2mm was grown by a spontaneous nucleation technique using KF as the flux. The composition of the studied single crystal was defined to be Ba0.798Ca0.202Zr0.006Ti0.994O3, corresponding to a tetragonal phase at room temperature. The oriented single crystal exhibited a quasi-static piezoelectric constant of approximately 232 pC/N. The effective piezoelectric coefficient d33* of the single domain crystal obtained under a unipolar electric field of 35 kV/cm was 179 pm/V. Rayleigh analysis was used to identify the intrinsic and extrinsic contributions to the room-temperature piezoelectricity of BCZT single crystal. The extrinsic contribution was estimated up to 40% due to the irreversible domain wall movement. Furthermore a sixth-order polynomial of Landau expansion was employed to analyze the intrinsic contribution to piezoelectricity of BCZT single crystal. The large energy barriers inhibited polarization rotations, leading to the relatively low piezoelectricity.

  3. Crystallization and electrical characteristics of ferroelectric Bi{sub 3.15}Nd{sub 0.85}Ti{sub 3}O{sub 12} thin films prepared by a sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Y. [Department of Physics, Jianghan University, Wuhan 430056 (China); Department of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Lu, C.J. [Department of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China)], E-mail: chaojing_lu@yahoo.com; Qi, Y.J. [Department of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Zhou, Y.H. [Department of Physics, Jianghan University, Wuhan 430056 (China)

    2008-07-01

    Ferroelectric Bi{sub 3.15}Nd{sub 0.85}Ti{sub 3}O{sub 12} (BNdT) thin films were deposited on Pt/Ti/SiO{sub 2}/Si substrates using a sol-gel process and Bi(NO{sub 3}){sub 3} was used as one of starting materials. Upon heating the major weight loss of the wet films occurred below 320 deg. C and nitrogen was almost completely removed at 650 deg. C. The films began to crystallize around 520 deg. C. The films annealed at 750 deg. C contain grains of 50-100 nm in diameter. The BNdT film capacitors with Pt top electrodes exhibited well-saturated hysteresis loops with a remanent polarization (2P{sub r}) of 57.4 {mu}C/cm{sup 2} and a coercive field of 108.3 kV/cm. The Pt/BNdT/Pt capacitors did not show any significant fatigue up to 6x10{sup 10} read/write switching cycles, and the retained charges remained nearly constant up to 10{sup 4} s after applying a writing pulse. The leakage current density of the BNdT films is less than 5x10{sup -8} A/cm{sup 2} under a low external field below 73 kV/cm.

  4. Large ferroelectric polarization of TiN/Hf0.5Zr0.5O2/TiN capacitors due to stress-induced crystallization at low thermal budget

    Science.gov (United States)

    Kim, Si Joon; Narayan, Dushyant; Lee, Jae-Gil; Mohan, Jaidah; Lee, Joy S.; Lee, Jaebeom; Kim, Harrison S.; Byun, Young-Chul; Lucero, Antonio T.; Young, Chadwin D.; Summerfelt, Scott R.; San, Tamer; Colombo, Luigi; Kim, Jiyoung

    2017-12-01

    We report on atomic layer deposited Hf0.5Zr0.5O2 (HZO)-based capacitors which exhibit excellent ferroelectric (FE) characteristics featuring a large switching polarization (45 μC/cm2) and a low FE saturation voltage (˜1.5 V) as extracted from pulse write/read measurements. The large FE polarization in HZO is achieved by the formation of a non-centrosymmetric orthorhombic phase, which is enabled by the TiN top electrode (TE) having a thickness of at least 90 nm. The TiN films are deposited at room temperature and annealed at 400 °C in an inert environment for at least 1 min in a rapid thermal annealing system. The room-temperature deposited TiN TE acts as a tensile stressor on the HZO film during the annealing process. The stress-inducing TiN TE is shown to inhibit the formation of the monoclinic phase during HZO crystallization, forming an orthorhombic phase that generates a large FE polarization, even at low process temperatures.

  5. Optical evidences for an intermediate phase in relaxor ferroelectric Pb(In1/2Nb1/2O3-Pb(Mg1/3Nb2/3O3-PbTiO3 single crystals

    Directory of Open Access Journals (Sweden)

    Xiaolong Zhang

    2016-02-01

    Full Text Available The mechanism of low-temperature structural transformation and evolution of polar nano-structures in relaxor ferroelectric Pb(In1/2Nb1/2O3-Pb(Mg1/3Nb2/3O3-xPbTiO3 (x = 0.33, 0.35, and 0.42 single crystals have been investigated with the aid of temperature dependent low-wavenumber Raman scattering (LWRS and photoluminescence (PL spectra. The E(TO1 phonon mode reveals the characteristic relaxational polarization fluctuations associated with the reorientation of either polar nano-regions or polar nano-domains. It was found that these mechanisms are not independent and they can be ascribed to the phonon localization. In addition, a short-range monoclinic phase (Mc can be found below 250 K in the tetragonal phase region by LWRS, which is always associated with the morphotropic phase boundary (MPB and excellent electromechanical properties. It is interesting that PL spectra confirm these results. The present work indicates that external field modulation and change of composition can result in the monoclinic phase and co-existence of multi-phase.

  6. Micromachining Lithium Niobate for Rapid Prototyping of Resonant Biosensors

    International Nuclear Information System (INIS)

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

    2014-01-01

    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

  7. Thermodynamic studies on the ferroelectric phase transition in neutron irradiated (LixK1-x)2SO4 crystals at high temperature

    International Nuclear Information System (INIS)

    Kassem, M.E.; El-Khatib, A.M.; Ammar, E.A.; Denton, M.M.

    1989-05-01

    Thermodynamic studies of (Li x K 1-x ) 2 SO 4 , LKS, mixed crystals have been made in the concentration range (x=0.1,0.2,...,x=0.5). The thermal behavior has been investigated by differential thermal analysis, DTA, and differential scanning calorimeter, DSC, in the vicinity of high temperature phases. Also, the effect of the mixed neutron field of fast and thermal neutrons (10% of the reactor neutron pile is fast neutrons) on the thermal properties of mixed crystals was studied. The results showed a change in the transition temperature Tc, as well as the value of specific heat Cp at transition temperature, due to the change of stoichiometric ratio and radiation doses. The change of enthalpy and entropy of mixed crystals have been estimated numerically. The obtained small values of ΔS/R is characteristic of incommensurate phase transition as previously confirmed by the results of neutron diffraction technique. (author). 16 refs, 5 figs, 1 tab

  8. The compact converter of Bessel beams of zero and second orders on the basis of z-cut lithium niobate

    International Nuclear Information System (INIS)

    Paranin, V D; Karpeev, S V; Khonina, S N; Tukmakov, K N

    2016-01-01

    Transformation of zero-order Bessel beams into a second-order vortex beam in the process of propagation in a c-cut of lithium niobate LiNbO 3 crystal has been investigated experimentally. The possibility of controlling beam transformation by means of changing the curve radius of the illuminating beam is shown. The possibility of Bessel beam transforming by compact devices on the basis of thin c-cuts of uniaxial crystals with a diffraction mask formed on their surface is proved. (paper)

  9. Thick-film processing of Pb5Ge3O11-based ferroelectric glass-ceramics

    International Nuclear Information System (INIS)

    Cornejo, I.A.; Haun, M.J.

    1996-01-01

    Processing techniques were investigated to produce c-axis orientation, or texture, of ferroelectric Pb 5 Ge 3 O 11 -based glass-ceramic compositions during crystallization of amorphous thick-film printed samples from the Pb 5 Ge 3 O 11 -PbTiO 3 (PG-PT) and Pb 5 Ge 3 O 11 -Pb(Zr 1/2 Ti 1/2 )O 3 (PG-PZT) systems. In these systems the PG crystallized into a ferroelectric phase, producing a multiple ferroelectric phase composite at low temperatures, PG-PT or PG-PZT. In this way the non-ferroelectric component of traditional ferroelectric glass-ceramics was eliminated

  10. Orientational order parameters of a de Vries-type ferroelectric liquid crystal obtained by polarized Raman spectroscopy and x-ray diffraction

    Czech Academy of Sciences Publication Activity Database

    Sanchez-Castillo, A.; Osipov, M.A.; Jagiella, S.; Nguyen, Z.H.; Kašpar, Miroslav; Hamplová, Věra; Maclennan, J.; Giesselmann, F.

    2012-01-01

    Roč. 85, č. 6 (2012), "061703-1"-"061703-18" ISSN 1539-3755 Institutional research plan: CEZ:AV0Z10100520 Keywords : molecular and microscopic models * theories of liquid crystal structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.313, year: 2012

  11. Ferroelectrics principles, structure and applications

    CERN Document Server

    Merchant, Serena

    2014-01-01

    Ferroelectric physics is a theory on ferroelectric phase transition for explaining various related phenomena, which is different from dielectric physics. Ferroelectric materials are important functional materials for various applications such as NVRAMs, high energy density capacitors, actuators, MEMs, sonar sensors, microphones and scanning electron microscopes (SEM). This book investigates the dielectric, ferroelectric and energy storage properties of barium zirconate-titanate/barium calcium-titanate (BZT-BCT) based ceramic for high energy density capacitors. It also compares the energy storage capabilities of ceramic powders with polymer-ceramic nanocomposites; and discusses dielectric properties of ferroelectricity in composition distributions.

  12. Enhancement of Lithium Niobate nanophotonic structures via spin-coating technique for optical waveguides application

    Directory of Open Access Journals (Sweden)

    Fakhri Makram A.

    2017-01-01

    Full Text Available This work is dedicated to investigation of temperature effects in Lithium Niobate (LiNbO3 nanostructures. The LiNbO3 nanostructures were deposited on glass substrate by spin-coating technique. LiNbO3 was set down at 3000 rpm for 30 sec and annealed from 100 to 600 °C. The structures were characterized and analyzed by scanning electron microscopy (SEM and ultra-violet visible (UV-vis spectrophotometer. The measured results have showed that by increasing annealing temperatures, the structures start to be more crystallized and be more homogenized until the optimum arrangement was achieved. Once this was accomplished, it's applicable for optical waveguides development. Eventually, it starts to be less crystallization and non-homogeneous. Energy gap was recorded to be at average value of 3.9 eV.

  13. Effect of excess bismuth on the dielectric and piezoelectric properties of strontium bismuth niobate ceramics

    International Nuclear Information System (INIS)

    Verma, Maya; Tanwar, Amit; Sreenivas, K.

    2013-01-01

    Excess Bismuth Strontium Bismuth Niobate (Sr 2 Bi 2 Nb 2 O 9 + x wt% Bi 2 O 3 ) ceramics were prepared using conventional solid state reaction method by varying x in the range (x=0%wt - 20%wt). X-ray diffraction studies reveal no significant shift in the peak positions as the Bi content increases from 0.0 to 5%wt. However, at a higher content of Bi beyond x = 5wt% secondary phases relating to Bi 2 O 3 are identified. The c-axis orientation is found to be minimum for SBN ceramic prepared with 5% excess bismuth whereas with further increase in excess Bi 2 O 3 addition during processing, SBN ceramics show a much stronger c-axis orientation. Room temperature dielectric constant measured at 100 KHz is found to increase from 117 to 130 with increase in Bi content from x = 0 to 10wt% suggesting Bi addition has make up for the bismuth losses at higher sintering temperature (1200℃), however with further increase in Bi content (x > 10wt%), the dielectric constant decreases, and could be due to the increased probability of segregation of Bi on the grains of SBN ceramics. The improvement in ferroelectric properties were obtained when the bismuth excess is increased from 0% to 5%. It may be observed that on increasing the excess bismuth to 5%, the transition temperature increases from 424 to 450℃, while further increasing to 10%, transition becomes slightly diffused and phase transition temperature gets decreased to 398℃, which may be due to the formation of secondary phase. 5% excess Bi is found to enhance the dielectric and ferroelectricity properties, and any further increase of Bi in excess (>10%) during processing is found to degrade the electrical and functional properties of SBN. (author)

  14. Direct evidence of strong local ferroelectric ordering in a thermoelectric semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, Leena; Sekhon, Jagmeet S.; Arora, Ashima; Sheet, Goutam, E-mail: goutam@iisermohali.ac.in [Department of Physical Sciences, Indian Institute of Science Education and Research Mohali (IISER M), Sector 81, S. A. S. Nagar, Manauli PO-140306 (India); Guin, Satya N.; Negi, Devendra S.; Datta, Ranjan; Biswas, Kanishka, E-mail: kanishka@jncasr.ac.in [New Chemistry Unit and International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore 560064 (India)

    2014-09-15

    It is thought that the proposed new family of multi-functional materials, namely, the ferroelectric thermoelectrics may exhibit enhanced functionalities due to the coupling of the thermoelectric parameters with ferroelectric polarization in solids. Therefore, the ferroelectric thermoelectrics are expected to be of immense technological and fundamental significance. As a first step towards this direction, it is most important to identify the existing high performance thermoelectric materials exhibiting ferroelectricity. Herein, through the direct measurement of local polarization switching, we show that the recently discovered thermoelectric semiconductor AgSbSe{sub 2} has local ferroelectric ordering. Using piezo-response force microscopy, we demonstrate the existence of nanometer scale ferroelectric domains that can be switched by external electric field. These observations are intriguing as AgSbSe{sub 2} crystalizes in cubic rock-salt structure with centro-symmetric space group (Fm–3m), and therefore, no ferroelectricity is expected. However, from high resolution transmission electron microscopy measurement, we found the evidence of local superstructure formation which, we believe, leads to local distortion of the centro-symmetric arrangement in AgSbSe{sub 2} and gives rise to the observed ferroelectricity. Stereochemically active 5S{sup 2} lone-pair of Sb may also give rise to local structural distortion thereby creating ferroelectricity in AgSbSe{sub 2}.

  15. Guest–host interaction in ferroelectric liquid crystal–nanoparticle ...

    Indian Academy of Sciences (India)

    Administrator

    nanoparticles have been added to the pure ferroelectric liquid crystal (FLC) Felix 17/100. The nanoparticles .... To prepare the NPs, doped-FLC sample, an appropriate amount (in the .... permittivity and f the frequency while n, m and k are the.

  16. Phenomenological theory of the dielectric response of lead magnesium niobate and lead scandium tantalate

    International Nuclear Information System (INIS)

    Qian, H.; Bursill, L.A.

    1997-01-01

    The influence of the random field effects originating from charges chemical defects and non-domain textures of the formation and dynamics of polar clusters is analyzed. The spatial distribution of the local fields is not totally random but contains some correlations in direction and strength. Polar clusters are classified to be dynamic or frozen according to their dynamic characteristics in the random fields. The relaxation formula of a dipolar moment in an anisotropic double-well potential is deduced. Two percolation models are introduced, one to account for frustration effects associated with multiple orientations of polar clusters, which results in a broad diffuse dielectric response and the second to account for the case whereby there may be a phase transition to a ferroelectric state. The dielectric permittivity and dissipation factor of the typical relaxors lead magnesium niobate and lead scandium tantalate are predicted as a function of both temperature and frequency, which results are in good agreement with the experimental measurements. 30 refs., 9 figs

  17. Modification of both d33 and TC in a potassium-sodium niobate ternary system.

    Science.gov (United States)

    Wu, Bo; Wu, Jiagang; Xiao, Dingquan; Zhu, Jianguo

    2015-12-28

    In this work, we simultaneously achieved a giant d33 and a high TC in a lead-free piezoelectric ternary system of (1-x-y)K0.48Na0.52NbO3-xBiFeO3-yBi0.5Na0.5ZrO3 {(1-x-y)KNN-xBF-yBNZ}. Owing to the rhombohedral-orthorhombic-tetragonal (R-O-T) phase coexistence and the enhanced dielectric and ferroelectric properties, the ceramics with a composition of (x = 0.006, y = 0.04) show a giant d33 of ∼428 pC N(-1) together with a TC of ∼318 °C, thereby proving that the design of ternary systems is an effective way to achieve both high d33 and high TC in KNN-based materials. In addition, a good thermal stability for piezoelectricity was also observed in these ceramics (e.g., d33 > 390 pC N(-1), T ≤ 300 °C). This is the first time such a good comprehensive performance in potassium-sodium niobate materials has been obtained. As a result, we believe that this type of material system with both giant d33 and high TC is a promising candidate for high-temperature piezoelectric devices.

  18. Effect of chemical pressure on competition and cooperation between polar and antiferrodistortive distortions in sodium niobate

    Science.gov (United States)

    Jauhari, Mrinal; Mishra, S. K.; Mittal, R.; Sastry, P. U.; Chaplot, S. L.

    2017-12-01

    We present results obtained from a combination of dielectric and x-ray diffraction measurements for compositional design of (1 -x )NaNb O3-x BaTi O3(NNBT x ) , which can induce interferroelectric phase transitions. Anomalies are observed in dielectric measurements performed for various compositions at 300 K, as well as at different temperatures for NNBT03. We observed the appearance(disappearance) of the superlattice reflections along with change in the intensities of the main perovskite peaks in the powder x-ray diffraction data, which provide clear evidences for structural phase transitions with composition and temperature. We found that increasing the concentration of BaTi O3 leads to the suppression of out-of-phase rotation of octahedra and an increment in tetragonality (c /a ratio), which promotes the polar mode at room temperature. The temperature-dependent powder diffraction study shows that the ferroelectric rhombohedral phase of pure sodium niobate gets suppressed for the composition x =0.03 , and the monoclinic phase C c gets stabilized at low temperature. The monoclinic phase is believed to provide for a flexible polarization rotation and is considered to be directly linked to the high-performance piezoelectricity in materials due to presence of more easy axes for spontaneous polarizations than the rhombohedral phase.

  19. Phase transitions of sodium niobate powder and ceramics, prepared by solid state synthesis

    Science.gov (United States)

    Koruza, J.; Tellier, J.; Malič, B.; Bobnar, V.; Kosec, M.

    2010-12-01

    Phase transitions of sodium niobate, prepared by the solid state synthesis method, were examined using dielectric measurements, differential scanning calorimetry, and high temperature x-ray diffraction, in order to contribute to the clarification of its structural behavior below 400 °C. Four phase transitions were detected in the ceramic sample using dielectric measurements and differential scanning calorimetry and the obtained temperatures were in a good agreement with previous reports for the transitions of the P polymorph. The anomaly observed by dielectric measurements in the vicinity of 150 °C was frequency dependent and could be related to the dynamics of the ferroelectric nanoregions. The phase transitions of the as-synthesized NaNbO3 powder were investigated using differential scanning calorimetry and high temperature x-ray diffraction. The results show the existence of the Q polymorph at room temperature, not previously reported for the powder, which undergoes a transition to the R polymorph upon heating through a temperature region between 265 and 326.5 °C. This transition is mainly related to the displacement of Na into a more symmetric position and a minor change in the tilting system. The structures at room temperature, 250, 300, and 420 °C were refined by the Rietveld method and the evolution of the tilting system of the octahedral network and cationic displacement are reported.

  20. Phase transitions of sodium niobate powder and ceramics, prepared by solid state synthesis

    International Nuclear Information System (INIS)

    Koruza, J.; Tellier, J.; Malic, B.; Bobnar, V.; Kosec, M.

    2010-01-01

    Phase transitions of sodium niobate, prepared by the solid state synthesis method, were examined using dielectric measurements, differential scanning calorimetry, and high temperature x-ray diffraction, in order to contribute to the clarification of its structural behavior below 400 deg. C. Four phase transitions were detected in the ceramic sample using dielectric measurements and differential scanning calorimetry and the obtained temperatures were in a good agreement with previous reports for the transitions of the P polymorph. The anomaly observed by dielectric measurements in the vicinity of 150 deg. C was frequency dependent and could be related to the dynamics of the ferroelectric nanoregions. The phase transitions of the as-synthesized NaNbO 3 powder were investigated using differential scanning calorimetry and high temperature x-ray diffraction. The results show the existence of the Q polymorph at room temperature, not previously reported for the powder, which undergoes a transition to the R polymorph upon heating through a temperature region between 265 and 326.5 deg. C. This transition is mainly related to the displacement of Na into a more symmetric position and a minor change in the tilting system. The structures at room temperature, 250, 300, and 420 deg. C were refined by the Rietveld method and the evolution of the tilting system of the octahedral network and cationic displacement are reported.

  1. Label-free investigation of the effects of lithium niobate polarization on cell adhesion

    Science.gov (United States)

    Mandracchia, B.; Gennari, O.; Paturzo, M.; Grilli, S.; Ferraro, P.

    2017-06-01

    The determination of contact area is pivotal to understand how biomaterials properties influence cell adhesion. In particular, the influence of surface charges is well-known but still controversial, especially when new functional materials and methods are introduced. Here, we use for the first time Holographic Total Internal Reflection Microscopy (HoloTIRM) to study the influence of the spontaneous polarization of ferroelectric lithium niobate (LN) on the adhesion properties of fibroblast cells. The selective illumination of a very thin region directly above the substrate, achieved by Total Internal Reflection, provides high-contrast images of the contact regions. Holographic recording, on the other hand, allows for label-free quantitative phase imaging of the contact areas between cells and LN. Phase signal is more sensitive in the first 100nm and, thus more reliable in order to locate focal contacts. This work shows that cells adhering on negatively polarized LN present a significant increase of the contact area in comparison with cells adhering on the positively polarized LN substrate, as well as an intensification of contact vicinity. This confirms the potential of LN as a platform for investigating the role of charges on cellular processes. The similarity of cell adhesion behavior on negatively polarized LN and glass control also confirms the possibility to use LN as an active substrate without impairing cell behavior.

  2. Effect of powder processing conditions on the electromechanical properties of lithium doped potassium sodium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Mensur-Alkoy, E.; Berksoy-Yavuz, A.

    2016-07-01

    Lithium doped potassium sodium niobate ceramics with (K0.50−x/2Na0.50−x/2Lix)NbO3 composition where x=0.04 and 0.07 were fabricated by solid state calcination and pressureless sintering methods. However, two different powder processing and calcination routes were used in this study and their effect on the structural and electrical properties were investigated and discussed. The routes were namely loose calcination and compact calcination. A general trend of decreasing grain size was observed in the sintered ceramics prepared from these powders. The most drastic effect was observed on the electromechanical properties of the samples, where the maximum strain of 7% lithium modified sample under an E-field of 50kV/cm was increased from 0.09% to 0.12% by changing processing route. Furthermore, hysteretic behavior of the strain was found to decrease. This tendency was also valid for ferroelectric hysteresis property, with remnant polarization (2Pr) increasing from 23μC/cm2 to 46μC/cm2. The improvements observed in the electrical properties were discussed on the basis of chemical homogeneity and uniform ionic distribution. (Author)

  3. Electronic ferroelectricity in carbon-based systems: from reality of organic conductors to promises of polymers and graphene nano-ribbons

    International Nuclear Information System (INIS)

    Kirova, Natasha; Brazovskii, Serguei

    2014-01-01

    Ferroelectricity is a rising demand in fundamental and applied solid state physics. Ferroelectrics are used in microelectronics as active gate materials, in capacitors, electro-optical-acoustic modulators, etc. There is a particular demand for plastic ferroelectrics, e.g. as a sensor for acoustic imaging in medicine and beyond, in shapeable capacitors, etc. Microscopic mechanisms of ferroelectric polarization in traditional materials are typically ionic. In this talk we discuss the electronic ferroelectrics – carbon-based materials: organic crystals, conducting polymers and graphene nano-ribbons. The motion of walls, separating domains with opposite electric polarisation, can be influenced and manipulated by terahertz and infra-red range optics

  4. Surface acoustic waves in acoustic superlattice lithium niobate coated with a waveguide layer

    Science.gov (United States)

    Yang, G. Y.; Du, J. K.; Huang, B.; Jin, Y. A.; Xu, M. H.

    2017-04-01

    The effects of the waveguide layer on the band structure of Rayleigh waves are studied in this work based on a one-dimensional acoustic superlattice lithium niobate substrate coated with a waveguide layer. The present phononic structure is formed by the periodic domain-inverted single crystal that is the Z-cut lithium niobate substrate with a waveguide layer on the upper surface. The plane wave expansion method (PWE) is adopted to determine the band gap behavior of the phononic structure and validated by the finite element method (FEM). The FEM is also used to investigate the transmission of Rayleigh waves in the phononic structure with the interdigital transducers by means of the commercial package COMSOL. The results show that, although there is a homogeneous waveguide layer on the surface, the band gap of Rayleigh waves still exist. It is also found that increasing the thickness of the waveguide layer, the band width narrows and the band structure shifts to lower frequency. The present approach can be taken as an efficient tool in designing of phononic structures with waveguide layer.

  5. Irradiation-induced modification of the material parameters in magnesium-doped lithium niobate

    International Nuclear Information System (INIS)

    Jentjens, Lena

    2010-01-01

    In the framework of this thesis the material properties of lithium niobate are directedly influenced by the irradiation with 3 He ions with an energy of 40 MeV. In the first part the irradiation-induced material changes are intensively studied. Long-time stable changes of the refractive index are measured in the range of up to 6.10 -3 , which depend on the radiation dose and exhibit until now no saturation behaviour. Accompanied is this change by an also dose-dependent deformation as well as a brownish change of color of the crystals. Furthermore a by several orders of magnitude increased electrical dark- and photoconductivity, which depends on the ion dose and exhibits until now also no saturation behaviour. An effect independent on the ion dose is the reduction of the coercive field strength by about 10%. Furthermore it was stated the quantity of the effects not only depends on the absolute dose, but also on the irradiation direction in view of the crystallographic c-axis. The second part of this thesis deals with the generation of microscopic structures in lithium niobate. By an ion microbeam respectively a shiftable slit aperture the fabrication of refractive-index gratings is pursued. Grating with periodicity lengths in the range of 12-160 μm could until now be detected and promise in comparison with photorefractive gratings the advance of larger stability.

  6. Surface acoustic waves in acoustic superlattice lithium niobate coated with a waveguide layer

    Directory of Open Access Journals (Sweden)

    G. Y. Yang

    2017-04-01

    Full Text Available The effects of the waveguide layer on the band structure of Rayleigh waves are studied in this work based on a one-dimensional acoustic superlattice lithium niobate substrate coated with a waveguide layer. The present phononic structure is formed by the periodic domain-inverted single crystal that is the Z-cut lithium niobate substrate with a waveguide layer on the upper surface. The plane wave expansion method (PWE is adopted to determine the band gap behavior of the phononic structure and validated by the finite element method (FEM. The FEM is also used to investigate the transmission of Rayleigh waves in the phononic structure with the interdigital transducers by means of the commercial package COMSOL. The results show that, although there is a homogeneous waveguide layer on the surface, the band gap of Rayleigh waves still exist. It is also found that increasing the thickness of the waveguide layer, the band width narrows and the band structure shifts to lower frequency. The present approach can be taken as an efficient tool in designing of phononic structures with waveguide layer.

  7. Stability of lithium niobate on irradiation at elevated temperature

    International Nuclear Information System (INIS)

    Primak, W.; Gavin, A.P.; Anderson, T.T.; Monahan, E.

    1977-01-01

    In contrast to results obtained for neutron irradiation in a thermal reactor near room temperature, lithium niobate plates irradiated in the Experimental Breeder Reactor II (EBR-II) did not become metamict. This is attributed to the elevated temperature of the EBR-II. Ion bombardment experiments indicate that to avoid disordering of lithium niobate on irradiation, its temperature should be maintained above 673 K. Evidence for ionic conductivity was found at 873 K, indicating that it would be inadvisable to permit the temperature to rise that high, particularly with voltage across the plate. In reactor application as a microphone transducer, it is tentatively recommended that the lithium niobate be maintained in the middle of this temperature range for a major portion of reactor operating time

  8. Ferroelectric Negative Capacitance Domain Dynamics

    OpenAIRE

    Hoffmann, Michael; Khan, Asif Islam; Serrao, Claudy; Lu, Zhongyuan; Salahuddin, Sayeef; Pešić, Milan; Slesazeck, Stefan; Schroeder, Uwe; Mikolajick, Thomas

    2017-01-01

    Transient negative capacitance effects in epitaxial ferroelectric Pb(Zr$_{0.2}$Ti$_{0.8}$)O$_3$ capacitors are investigated with a focus on the dynamical switching behavior governed by domain nucleation and growth. Voltage pulses are applied to a series connection of the ferroelectric capacitor and a resistor to directly measure the ferroelectric negative capacitance during switching. A time-dependent Ginzburg-Landau approach is used to investigate the underlying domain dynamics. The transien...

  9. Nanoparticles Doped, Photorefractive Liquid Crystals

    National Research Council Canada - National Science Library

    Kaczmarek, Malgosia

    2005-01-01

    ...: The main objectives of this exploratory, short project will concern the study of the quality of liquid crystal cells with diluted suspensions of ferroelectric nanoparticles and their photorefractive properties...

  10. Multiwatt-level continuous-wave midwave infrared generation using difference frequency mixing in periodically poled MgO-doped lithium niobate.

    Science.gov (United States)

    Guha, Shekhar; Barnes, Jacob O; Gonzalez, Leonel P

    2014-09-01

    Over 3.5 W of continuous-wave power at 3.4 μm was obtained by single-pass difference frequency mixing of 1.064 and 1.55 μm fiber lasers in a 5 cm long periodically poled lithium niobate crystal. Good agreement was obtained between the observed temperature dependence of the generated power and the prediction from focused Gaussian beam theory.

  11. Ferroelectricity the fundamentals collection

    CERN Document Server

    Jimenez, Basilio

    2008-01-01

    This indispensable collection of seminal papers on ferroelectricity provides an overview over almost a hundred years of basic and applied research. Containing historic contributions from renowned authors, this book presents developments in an area of science that is still rapidly growing. Although primarily aimed at scientists and academics involved in research, this will also be of use to students as well as newcomers to the field.

  12. Cofiring behavior and interfacial structure of NiCuZn ferrite/PMN ferroelectrics composites for multilayer LC filters

    International Nuclear Information System (INIS)

    Miao Chunlin; Zhou Ji; Cui Xuemin; Wang Xiaohui; Yue Zhenxing; Li Longtu

    2006-01-01

    The cofiring behavior, interfacial structure and cofiring migration between NiCuZn ferrite and lead magnesium niobate (PMN)-based relaxor ferroelectric materials were investigated via thermomechanical analyzer (TMA), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Mismatched sintering shrinkage between NiCuZn ferrite and PMN was modified by adding an appropriate amount of sintering aids, Bi 2 O 3 , into NiCuZn ferrite. Pyrochlore phase appeared in the mixture of NiCuZn ferrite and PMN, which is detrimental to the final electric properties of LC filters. EDS results indicated that the interdiffusion at the heterogeneous interfaces in the composites, such as Fe, Pb, Zn, existed which can strengthen combinations between ferrite layers and ferroelectrics layers

  13. Luminescence life time and time-resolved spectroscopy of Cr3+ ions in strontium barium niobate

    International Nuclear Information System (INIS)

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

    2006-01-01

    This paper reports on the photo-luminescence spectroscopic results of congruent strontium-barium-niobate (SBN) crystals doped with Cr 2 O, 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 band-width full-width at half-maximum (FWHM) larger than 1700 cm -1 and has been ascribed to the vibronically assisted 4 T 2 →4 A 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 2 E →4 A 2 radiative transition (R-line)

  14. Note: High-power piezoelectric transformer fabricated with ternary relaxor ferroelectric Pb(Mg(1/3)Nb(2/3))O3-Pb(In(1/2)Nb(1/2))O3-PbTiO3 single crystal.

    Science.gov (United States)

    Wang, Qing; Ma, Chuanguo; Wang, Feifei; Liu, Bao; Chen, Jianwei; Luo, Haosu; Wang, Tao; Shi, Wangzhou

    2016-03-01

    A plate-shaped piezoelectric transformer was designed and fabricated using ternary relaxor ferroelectric single crystal Pb(Mg(1/3)Nb(2/3))O3-Pb(In(1/2)Nb(1/2))O3-PbTiO3. Both the input and output sections utilized the transverse-extensional vibration mode. The frequency and load dependences of the electrical properties for the proposed transformer were systematically studied. Results indicated that under a matching load resistance of 14.9 kΩ, a maximum output power of 2.56 W was obtained with the temperature rise less than 5 °C. The corresponding power density reached up to 50 W/cm(3). This ternary single-crystal transformer had potential applications in compact-size converters requiring high power density.

  15. Nanoscale organic ferroelectric resistive switches

    NARCIS (Netherlands)

    Khikhlovskyi, V.; Wang, R.; Breemen, A.J.J.M. van; Gelinck, G.H.; Janssen, R.A.J.; Kemerink, M.

    2014-01-01

    Organic ferroelectric resistive switches function by grace of nanoscale phase separation in a blend of a semiconducting and a ferroelectric polymer that is sandwiched between metallic electrodes. In this work, various scanning probe techniques are combined with numerical modeling to unravel their

  16. Sub-band-gap laser micromachining of lithium niobate

    DEFF Research Database (Denmark)

    Christensen, F. K.; Müllenborn, Matthias

    1995-01-01

    method is reported which enables us to do laser processing of lithium niobate using sub-band-gap photons. Using high scan speeds, moderate power densities, and sub-band-gap photon energies results in volume removal rates in excess of 106µm3/s. This enables fast micromachining of small piezoelectric...

  17. Frontiers of ferroelectricity a special issue of the journal of materials science

    CERN Document Server

    Lang, Sidney B

    2007-01-01

    The book presents theory, fundamentals and some applications of ferroelectricy. The 24 chapters comprise reviews and research reports covering the spectrum of ferroelectricity. It is intended to describe the current levels of understanding of various aspects of ferroelectricity as presented by authorities in the field. Topics include relaxors, piezoelectrics, microscale and nanoscale studies, polymers and composites, unusual properties, and techniques and devices. The information in this book is intended for physicists, engineers and materials scientists working with ferroelectric materials including ceramics, single crystals, polymers, composites and even some biological materials.

  18. The use of one-dimensional Niobate to improve MgH{sub 2} hydrogen sorption

    Energy Technology Data Exchange (ETDEWEB)

    Brum, M.C., E-mail: mbrum@metalmat.ufrj.br; Conceição, M.O.T. da; Jardim, P.M.; Santos, D.S. dos

    2014-12-05

    Highlights: • The 1-D Niobate W and Niobate C catalysts were synthesized. • The composites MgH{sub 2} + 5 wt.% catalysts were obtained by 20 min of mechanical milling. • The synthesized wired-like material 1-D Niobate W showed to be a promising catalyst. • A desorption capacity of 6.0 wt.%. of H{sub 2} was attained in 10 min with MgH{sub 2} + 5 wt.% 1-D Niobate W. - Abstract: A study was performed on the hydrogen absorption/desorption properties of MgH{sub 2} with the addition of Niobates synthesized by hydrothermal treatment of Nb{sub 2}O{sub 5} in 10 M NaOH. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) were used to evaluate their synthesis and show the morphological and crystallographic differences between Nb{sub 2}O{sub 5} used as a precursor and the Niobates produced, the one-dimensional wired type, 1-D Niobate W and the cuboid one, Niobate C. The ball milling of MgH{sub 2} with the Niobates was performed within only 20 min and afterwards the Differential Scanning Calorimetry (DSC) examination of MgH{sub 2} + 1-D Niobate W and MgH{sub 2} + Niobate C showed the shifting of the peaks for both composites in comparison to pure MgH{sub 2}. The influence of the two different types of Niobates and also the Nb{sub 2}O{sub 5} on the hydrogen absorption/desorption capacity was evaluated at 350 °C. The higher absorption and desorption values were attained by the MgH{sub 2} + 5 wt.% 1-D Niobate W composite, reaching, in 10 min, approximately 5.0 wt.% and 6.0 wt.%, respectively. The possible mechanism involved in such property improvement upon adding niobium based catalysts with different morphology and structure was discussed.

  19. Systematic prediction of new ferroelectric inorganic materials in point group 6

    International Nuclear Information System (INIS)

    Abrahams, S.C.

    1990-01-01

    A total of seven new families and sixteen structurally different inorganic materials with point group 6 are shown to satisfy the criteria presented previously by the present author for predicting ferroelectricity. In case each prediction is experimentally verified, the 183 individual entries for point group 6 listed in the Inorganic Crystal Structure Database will result in over 80 new ferroelectrics, of which about 30 are rare-earth isomorphs. The total number of 'pure'

  20. Raman and IR phonons in ferroelectric Sr.sub.0.35./sub.Ba.sub.0.69./sub.Nb.sub.2./sub.O.sub.6.04./sub. single crystals

    Czech Academy of Sciences Publication Activity Database

    Buixaderas, Elena; Gregora, Ivan; Hlinka, Jiří; Dec, J.; Lukasiewicz, T.

    2013-01-01

    Roč. 86, 2-3 (2013), s. 217-229 ISSN 0141-1594 R&D Projects: GA ČR GAP204/10/0616 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectrics * Raman spectroscopy * IR spectroscopy * phonons * relaxors * tungsten-bronze materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.044, year: 2013

  1. CuInP₂S₆ Room Temperature Layered Ferroelectric.

    Science.gov (United States)

    Belianinov, A; He, Q; Dziaugys, A; Maksymovych, P; Eliseev, E; Borisevich, A; Morozovska, A; Banys, J; Vysochanskii, Y; Kalinin, S V

    2015-06-10

    We explore ferroelectric properties of cleaved 2-D flakes of copper indium thiophosphate, CuInP2S6 (CITP), and probe size effects along with limits of ferroelectric phase stability, by ambient and ultra high vacuum scanning probe microscopy. CITP belongs to the only material family known to display ferroelectric polarization in a van der Waals, layered crystal at room temperature and above. Our measurements directly reveal stable, ferroelectric polarization as evidenced by domain structures, switchable polarization, and hysteresis loops. We found that at room temperature the domain structure of flakes thicker than 100 nm is similar to the cleaved bulk surfaces, whereas below 50 nm polarization disappears. We ascribe this behavior to a well-known instability of polarization due to depolarization field. Furthermore, polarization switching at high bias is also associated with ionic mobility, as evidenced both by macroscopic measurements and by formation of surface damage under the tip at a bias of 4 V-likely due to copper reduction. Mobile Cu ions may therefore also contribute to internal screening mechanisms. The existence of stable polarization in a van-der-Waals crystal naturally points toward new strategies for ultimate scaling of polar materials, quasi-2D, and single-layer materials with advanced and nonlinear dielectric properties that are presently not found in any members of the growing "graphene family".

  2. Modelling of creep hysteresis in ferroelectrics

    Science.gov (United States)

    He, Xuan; Wang, Dan; Wang, Linxiang; Melnik, Roderick

    2018-05-01

    In the current paper, a macroscopic model is proposed to simulate the hysteretic dynamics of ferroelectric ceramics with creep phenomenon incorporated. The creep phenomenon in the hysteretic dynamics is attributed to the rate-dependent characteristic of the polarisation switching processes induced in the materials. A non-convex Helmholtz free energy based on Landau theory is proposed to model the switching dynamics. The governing equation of single-crystal model is formulated by applying the Euler-Lagrange equation. The polycrystalline model is obtained by combining the single crystal dynamics with a density function which is constructed to model the weighted contributions of different grains with different principle axis orientations. In addition, numerical simulations of hysteretic dynamics with creep phenomenon are presented. Comparison of the numerical results and their experimental counterparts is also presented. It is shown that the creep phenomenon is captured precisely, validating the capability of the proposed model in a range of its potential applications.

  3. Spectral evolution of Eu{sup 3+} doped Y{sub 3}NbO{sub 7} niobate induced by temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K-Y.; Durand, A. [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Heintz, J-M.; Veillere, A. [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Bordeaux INP, ICMCB, UPR 9048, F-33600 Pessac (France); Jubera, V., E-mail: veronique.jubera@u-bordeaux.fr [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France)

    2016-03-15

    A Eu{sup 3+} doped Y{sub 3}NbO{sub 7} niobate powder was synthetized using a polymerizable complex route. It gave rise to nanometric particles that crystallized in the fluorine structure, corresponding to the Y{sub 3}NbO{sub 7} 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 YNbO{sub 4} and Y{sub 2}O{sub 3}. Although the Y{sub 3}NbO{sub 7} 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. - Graphical abstract: Spectral evolution of Eu{sup 3+} doped Y{sub 3}NbO{sub 7} niobate induced by temperature.

  4. crystal

    Science.gov (United States)

    Yu, Yi; Huang, Yisheng; Zhang, Lizhen; Lin, Zhoubin; Sun, Shijia; Wang, Guofu

    2014-07-01

    A Nd3+:Na2La4(WO4)7 crystal with dimensions of ϕ 17 × 30 mm3 was grown by the Czochralski method. The thermal expansion coefficients of Nd3+:Na2La4(WO4)7 crystal are 1.32 × 10-5 K-1 along c-axis and 1.23 × 10-5 K-1 along a-axis, respectively. The spectroscopic characteristics of Nd3+:Na2La4(WO4)7 crystal were investigated. The Judd-Ofelt theory was applied to calculate the spectral parameters. The absorption cross sections at 805 nm are 2.17 × 10-20 cm2 with a full width at half maximum (FWHM) of 15 nm for π-polarization, and 2.29 × 10-20 cm2 with a FWHM of 14 nm for σ-polarization. The emission cross sections are 3.19 × 10-20 cm2 for σ-polarization and 2.67 × 10-20 cm2 for π-polarization at 1,064 nm. The fluorescence quantum efficiency is 67 %. The quasi-cw laser of Nd3+:Na2La4(WO4)7 crystal was performed. The maximum output power is 80 mW. The slope efficiency is 7.12 %. The results suggest Nd3+:Na2La4(WO4)7 crystal as a promising laser crystal fit for laser diode pumping.

  5. Ferroelectric Plasma Thruster

    National Research Council Canada - National Science Library

    Kovaleski, Scott D; Kemp, Mark A

    2008-01-01

    .... When radiofrequency high voltage is applied between the electrodes, through the thickness of the crystal, a combination of triple point and piezoelectric effects produce dense plasma on the crystal surface...

  6. Recharging processes, radiation induced strain and changes of OH - bands under H + ion implantation in Ti doped lithium niobate

    Science.gov (United States)

    Kumar, P.; Moorthy Babu, S.; Bhaumik, I.; Ganesamoorthy, S.; Karnal, A. K.; Kumar, Praveen; Rodrigues, G. O.; Sulania, I.; Kanjilal, D.; Pandey, A. K.; Raman, R.

    2010-01-01

    A systematic analysis of variations in structural and optical characteristics of Z-cut plates of titanium doped congruent lithium niobate single crystals implanted with 120 keV proton beam at various fluences of 10 15, 10 16 and 10 17 protons/cm 2 is presented. Through, high resolution X-ray diffraction, atomic force microscopy, Fourier transform infrared and UV-visible-NIR analysis of congruent lithium niobate, the correlation of properties before and after implantation are discussed. HRXRD (0 0 6) reflection by Triple Crystal Mode shows that both tensile and compressive strain peak are produced by the high fluence implantation. A distinct tensile peak was observed from implanted region for a fluence of 10 16 protons/cm 2. AFM micrographs indicate mountain ridges, bumps and protrusions on target surface on implantation. UV-visible-NIR spectra reveal an increase in charge transfer between Ti 3+/Ti 4+ and ligand oxygen for implantation with 10 15 protons/cm 2, while spectra for higher fluence implanted samples show complex absorption band in the region from 380-1100 nm. Variations of OH - stretching vibration mode were observed for cLN Pure, cLNT2% virgin, and implanted samples with FTIR spectra. The concentration of OH - ion before and after implantation was calculated from integral absorption intensity. The effect of 120 keV proton implantation induced structural, surface and optical studies were correlated.

  7. In situ transmission electron microscopy study of the microstructural origins for the electric field-induced phenomena in ferroelectric perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hanzheng [Iowa State Univ., Ames, IA (United States)

    2014-12-15

    Ferroelectrics are important materials due to their extensive technological applications, such as non-volatile memories, field-effect transistors, ferroelectric tunneling junctions, dielectric capacitors, piezoelectric transducers, sensors and actuators. As is well known, the outstanding dielectric, piezoelectric, and ferroelectric properties of these functional oxides originate from their ferroelectric domain arrangements and the corresponding evolution under external stimuli (e.g. electric field, stress, and temperature). Electric field has been known as the most efficient stimulus to manipulate the ferroelectric domains through polarization switching and alignment. Therefore, direct observation of the dynamic process of electric field-induced domain evolution and crystal structure transformation is of significant importance to understand the microstructural mechanisms for the functional properties of ferroelectrics. In this dissertation, electric field in situ transmission electron microscopy (TEM) technique was employed to monitor the real-time evolution of the domain morphology and crystal structure during various electrical processes: (1) the initial poling process, (2) the electric field reversal process, and (3) the electrical cycling process. Two types of perovskite-structured ceramics, normal ferroelectrics and relaxor ferroelectrics, were used for this investigation. In addition to providing the microscopic insight for some wellaccepted phase transformation rules, discoveries of some new or even unexpected physical phenomena were also demonstrated.

  8. Phase transitions and electrical characterizations of (K 0.5Na 0.5) 2x(Sr 0.6Ba 0.4) 5-xNb 10O 30 (KNSBN) ceramics with 'unfilled' and 'filled' tetragonal tungsten-bronze (TTB) crystal structure

    KAUST Repository

    Yao, Yingbang

    2012-12-01

    Alkali-doped strontium barium niobate (K 0.5Na 0.5) 2x(Sr 0.6Ba 0.4) 5-xNb 10O 30 (KNSBN) ceramics has been prepared by a conventional solid-state reaction method. The alkali-dopant concentration x has been varied from 0.24 to 1.15 so that the crystal structure was transformed from \\'unfilled\\' to \\'filled\\' tetragonal tungsten-bronze (TTB) structure. Apart from the change in the structural properties, the effects of the alkali-dopants on the phase transition as well as ferroelectric, piezoelectric and pyroelectric properties have also been investigated. Phase transitions have been studied in the temperature range of -200°C to 350°C. The origins of these phase transitions are discussed. The addition of the alkali-dopants enhances the ferroelectric, piezoelectric and pyroelectric properties of the KNSBN ceramics. Alkali-doping also favors abnormal grain growth and thus results in a porous microstructure, which might contribute to the enhancement of the pyroelectric performance. © 2012 Elsevier Ltd.

  9. Phase transitions and electrical characterizations of (K 0.5Na 0.5) 2x(Sr 0.6Ba 0.4) 5-xNb 10O 30 (KNSBN) ceramics with 'unfilled' and 'filled' tetragonal tungsten-bronze (TTB) crystal structure

    KAUST Repository

    Yao, Yingbang; Mak, C. L.; Ploss, Bernd

    2012-01-01

    Alkali-doped strontium barium niobate (K 0.5Na 0.5) 2x(Sr 0.6Ba 0.4) 5-xNb 10O 30 (KNSBN) ceramics has been prepared by a conventional solid-state reaction method. The alkali-dopant concentration x has been varied from 0.24 to 1.15 so that the crystal structure was transformed from 'unfilled' to 'filled' tetragonal tungsten-bronze (TTB) structure. Apart from the change in the structural properties, the effects of the alkali-dopants on the phase transition as well as ferroelectric, piezoelectric and pyroelectric properties have also been investigated. Phase transitions have been studied in the temperature range of -200°C to 350°C. The origins of these phase transitions are discussed. The addition of the alkali-dopants enhances the ferroelectric, piezoelectric and pyroelectric properties of the KNSBN ceramics. Alkali-doping also favors abnormal grain growth and thus results in a porous microstructure, which might contribute to the enhancement of the pyroelectric performance. © 2012 Elsevier Ltd.

  10. Nonlinear optical oscillation dynamics in high-Q lithium niobate microresonators.

    Science.gov (United States)

    Sun, Xuan; Liang, Hanxiao; Luo, Rui; Jiang, Wei C; Zhang, Xi-Cheng; Lin, Qiang

    2017-06-12

    Recent advance of lithium niobate microphotonic devices enables the exploration of intriguing nonlinear optical effects. We show complex nonlinear oscillation dynamics in high-Q lithium niobate microresonators that results from unique competition between the thermo-optic nonlinearity and the photorefractive effect, distinctive to other device systems and mechanisms ever reported. The observed phenomena are well described by our theory. This exploration helps understand the nonlinear optical behavior of high-Q lithium niobate microphotonic devices which would be crucial for future application of on-chip nonlinear lithium niobate photonics.

  11. Interface modulated currents in periodically proton exchanged Mg doped lithium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Neumayer, Sabine M.; Rodriguez, Brian J., E-mail: brian.rodriguez@ucd.ie, E-mail: gallo@kth.se [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4 (Ireland); Manzo, Michele; Gallo, Katia, E-mail: brian.rodriguez@ucd.ie, E-mail: gallo@kth.se [Department of Applied Physics, KTH-Royal Institute of Technology, Roslagstullbacken 21, 10691 Stockholm (Sweden); Kholkin, Andrei L. [Department of Physics and CICECO-Aveiro Institute of Materials, 3810-193 Aveiro, Portugal and Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation)

    2016-03-21

    Conductivity in Mg doped lithium niobate (Mg:LN) plays a key role in the reduction of photorefraction and is therefore widely exploited in optical devices. However, charge transport through Mg:LN and across interfaces such as electrodes also yields potential electronic applications in devices with switchable conductivity states. Furthermore, the introduction of proton exchanged (PE) phases in Mg:LN enhances ionic conductivity, thus providing tailorability of conduction mechanisms and functionality dependent on sample composition. To facilitate the construction and design of such multifunctional electronic devices based on periodically PE Mg:LN or similar ferroelectric semiconductors, fundamental understanding of charge transport in these materials, as well as the impact of internal and external interfaces, is essential. In order to gain insight into polarization and interface dependent conductivity due to band bending, UV illumination, and chemical reactivity, wedge shaped samples consisting of polar oriented Mg:LN and PE phases were investigated using conductive atomic force microscopy. In Mg:LN, three conductivity states (on/off/transient) were observed under UV illumination, controllable by the polarity of the sample and the externally applied electric field. Measurements of currents originating from electrochemical reactions at the metal electrode–PE phase interfaces demonstrate a memresistive and rectifying capability of the PE phase. Furthermore, internal interfaces such as domain walls and Mg:LN–PE phase boundaries were found to play a major role in the accumulation of charge carriers due to polarization gradients, which can lead to increased currents. The insight gained from these findings yield the potential for multifunctional applications such as switchable UV sensitive micro- and nanoelectronic devices and bistable memristors.

  12. Ferroelectric capacitor with reduced imprint

    Science.gov (United States)

    Evans, Jr., Joseph T.; Warren, William L.; Tuttle, Bruce A.; Dimos, Duane B.; Pike, Gordon E.

    1997-01-01

    An improved ferroelectric capacitor exhibiting reduced imprint effects in comparison to prior art capacitors. A capacitor according to the present invention includes top and bottom electrodes and a ferroelectric layer sandwiched between the top and bottom electrodes, the ferroelectric layer comprising a perovskite structure of the chemical composition ABO.sub.3 wherein the B-site comprises first and second elements and a dopant element that has an oxidation state greater than +4. The concentration of the dopant is sufficient to reduce shifts in the coercive voltage of the capacitor with time. In the preferred embodiment of the present invention, the ferroelectric element comprises Pb in the A-site, and the first and second elements are Zr and Ti, respectively. The preferred dopant is chosen from the group consisting of Niobium, Tantalum, and Tungsten. In the preferred embodiment of the present invention, the dopant occupies between 1 and 8% of the B-sites.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bazzan, Marco, E-mail: marco.bazzan@unipd.it; Sada, Cinzia, E-mail: cinzia.sada@unipd.it [Dipartimento di Fisica e Astronomia “G. Galilei,” Università di Padova, Via Marzolo 8, 35131 Padova (Italy)

    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.

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

    International Nuclear Information System (INIS)

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

    1985-01-01

    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 μm. 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

  15. Dielectric properties in the vicinity of the ferroelectric phase transition in a mixed crystal of deuterated betaine phosphate{sub 0.03} betaine phosphite{sub 0.97}

    Energy Technology Data Exchange (ETDEWEB)

    Banys, J.; Macutkevic, J.; Kajokas, A.; Brilingas, A.; Grigas, J. [Faculty of Physics, Vilnius University, Sauletekio 9, Vilnius 2040 (Lithuania); Klimm, C.; Voelkel, G. [Fakultaet fuer Physik und Geowissenschaften, Universitaet Leipzig, Linnestr. 5, 04103 Leipzig (Germany)

    2004-02-01

    The dielectric behaviour of ferroelectric hydrogen bonded deuterated betaine phosphate{sub 0.03} betaine phosphite{sub 0.97} (DBP{sub 0.03}DBPI{sub 0.97})is investigated in the region of the ferroelectric phase transition. Dielectric dispersion is investigated in the frequency range up to 12 GHz. The dielectric dynamics shows a critical slowing down. The frequency of the relaxational soft mode in the paraelectric phase varies according to the quasi-one-dimensional Ising model and decreases up to 0.31 GHz at the phase transition temperature (T{sub C}=272 K). The obtained activation energy for the deuteron flipping motion {delta}U=2.3kT{sub C}=0.054 eV shows the order-disorder character of the ferroelectric phase transition. The spontaneous polarisation, obtained from pyroelectric measurements, is also well explained using the quasi-one-dimensional Ising model. At low temperatures, the freezing phenomena in DBP{sub 0.03}DBPI{sub 0.97} revealed the complex dielectric permittivity behaviour characteristic for the transition into the dipolar glass state. The activation energy of this low temperature process was found to be E{sub b}=1297 K (0.041 eV) and the glass temperature was estimated to 73 K. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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

    Czech Academy of Sciences Publication Activity Database

    Nekvindová, P.; Švecová, B.; Cajzl, J.; Macková, Anna; Malinský, Petr; Oswald, Jiří; Kolitsch, A.; Špirková, J.

    2012-01-01

    Roč. 34, č. 4 (2012), s. 652-659 ISSN 0925-3467 R&D Projects: GA MŠk(CZ) LC06041; GA ČR GA106/09/0125; GA ČR(CZ) GAP106/10/1477 Institutional research plan: CEZ:AV0Z10480505; CEZ:AV0Z10100521 Keywords : Lithium niobate * Erbium * Ion implantation * Luminescence Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.918, year: 2012

  17. Phase diagrams of ferroelectric nanocrystals strained by an elastic matrix

    Science.gov (United States)

    Nikitchenko, A. I.; Azovtsev, A. V.; Pertsev, N. A.

    2018-01-01

    Ferroelectric crystallites embedded into a dielectric matrix experience temperature-dependent elastic strains caused by differences in the thermal expansion of the crystallites and the matrix. Owing to the electrostriction, these lattice strains may affect polarization states of ferroelectric inclusions significantly, making them different from those of a stress-free bulk crystal. Here, using a nonlinear thermodynamic theory, we study the mechanical effect of elastic matrix on the phase states of embedded single-domain ferroelectric nanocrystals. Their equilibrium polarization states are determined by minimizing a special thermodynamic potential that describes the energetics of an ellipsoidal ferroelectric inclusion surrounded by a linear elastic medium. To demonstrate the stability ranges of such states for a given material combination, we construct a phase diagram, where the inclusion’s shape anisotropy and temperature are used as two parameters. The ‘shape-temperature’ phase diagrams are calculated numerically for PbTiO3 and BaTiO3 nanocrystals embedded into representative dielectric matrices generating tensile (silica glass) or compressive (potassium silicate glass) thermal stresses inside ferroelectric inclusions. The developed phase maps demonstrate that the joint effect of thermal stresses and matrix-induced elastic clamping of ferroelectric inclusions gives rise to several important features in the polarization behavior of PbTiO3 and BaTiO3 nanocrystals. In particular, the Curie temperature displays a nonmonotonic variation with the ellipsoid’s aspect ratio, being minimal for spherical inclusions. Furthermore, the diagrams show that the polarization orientation with respect to the ellipsoid’s symmetry axis is controlled by the shape anisotropy and the sign of thermal stresses. Under certain conditions, the mechanical inclusion-matrix interaction qualitatively alters the evolution of ferroelectric states on cooling, inducing a structural transition

  18. Stress effects in ferroelectric perovskite thin-films

    Science.gov (United States)

    Zednik, Ricardo Johann

    The exciting class of ferroelectric materials presents the engineer with an array of unique properties that offer promise in a variety of applications; these applications include infra-red detectors ("night-vision imaging", pyroelectricity), micro-electro-mechanical-systems (MEMS, piezoelectricity), and non-volatile memory (NVM, ferroelectricity). Realizing these modern devices often requires perovskite-based ferroelectric films thinner than 100 nm. Two such technologically important material systems are (Ba,Sr)TiO3 (BST), for tunable dielectric devices employed in wireless communications, and Pb(Zr,Ti)O3 (PZT), for ferroelectric non-volatile memory (FeRAM). In general, the material behavior is strongly influenced by the mechanical boundary conditions imposed by the substrate and surrounding layers and may vary considerably from the known bulk behavior. A better mechanistic understanding of these effects is essential for harnessing the full potential of ferroelectric thin-films and further optimizing existing devices. Both materials share a common crystal structure and similar properties, but face unique challenges due to the design parameters of these different applications. Tunable devices often require very low dielectric loss as well as large dielectric tunability. Present results show that the dielectric response of BST thin-films can either resemble a dipole-relaxor or follow the accepted empirical Universal Relaxation Law (Curie-von Schweidler), depending on temperature. These behaviors in a single ferroelectric thin-film system are often thought to be mutually exclusive. In state-of-the-art high density FeRAM, the ferroelectric polarization is at least as important as the dielectric response. It was found that these properties are significantly affected by moderate biaxial tensile and compressive stresses which reversibly alter the ferroelastic domain populations of PZT at room temperature. The 90-degree domain wall motion observed by high resolution

  19. Programmable ferroelectric tunnel memristor

    Directory of Open Access Journals (Sweden)

    Andy eQuindeau

    2014-02-01

    Full Text Available We report an analogously programmable memristor based on genuine electronic resistive switching combining ferroelectric switching and electron tunneling. The tunnel current through an 8 unit cell thick epitaxial Pb(Zr[0.2]Ti[0.8]O[3] film sandwiched between La[0.7]Sr[0.3]MnO[3] and cobalt electrodes obeys the Kolmogorov-Avrami-Ishibashi model for bidimensional growth with a characteristic switching time in the order of 10^-7 seconds. The analytical description of switching kinetics allows us to develop a characteristic transfer function that has only one parameter viz. the characteristic switching time and fully predicts the resistive states of this type of memristor.

  20. Lithium niobate ultrasonic transducer design for Enhanced Oil Recovery.

    Science.gov (United States)

    Wang, Zhenjun; Xu, Yuanming; Gu, Yuting

    2015-11-01

    Due to the strong piezoelectric effect possessed by lithium niobate, a new idea that uses lithium niobate to design high-power ultrasonic transducer for Enhanced Oil Recovery technology is proposed. The purpose of this paper is to lay the foundation for the further research and development of high-power ultrasonic oil production technique. The main contents of this paper are as follows: firstly, structure design technique and application of a new high-power ultrasonic transducer are introduced; secondly, the experiment for reducing the viscosity of super heavy oil by this transducer is done, the optimum ultrasonic parameters for reducing the viscosity of super heavy oil are given. Experimental results show that heavy large molecules in super heavy oil can be cracked into light hydrocarbon substances under strong cavitation effect caused by high-intensity ultrasonic wave. Experiment proves that it is indeed feasible to design high-power ultrasonic transducer for ultrasonic oil production technology using lithium niobate. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Vacuum-evaporated ferroelectric films and heterostructures of vinylidene fluoride/trifluoroethylene copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Draginda, Yu. A., E-mail: lbf@ns.crys.ras.ru; Yudin, S G; Lazarev, V V; Yablonskii, S V; Palto, S P [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2012-05-15

    The potential of the vacuum method for preparing ferroelectric films and photonic heterostructures from organic materials is studied. Vacuum-evaporated films of fluoropolymers and heterostructures on their basis are obtained and their ferroelectric and spectral properties are studied. In particular, homogeneous films of the well-known piezoelectric polymer polyvinylidene fluoride and ferroelectric material vinylidene fluoride/trifluoroethylene copolymer (P(VDF/TFE)) are produced. Experimental studies of vacuum-evaporated P(VDF/TFE) films confirmed their ferroelectric properties. The heterostructures composed of alternating layers of P(VDF/TFE) copolymer molecules and azodye molecules are fabricated by vacuum evaporation. Owing to the controlled layer thickness and a significant difference in the refractive indices of the P(VDF/TFE) copolymer and azodyes, these heterostructures exhibit properties of photonic crystals. This finding is confirmed by the occurrence of a photonic band in the absorption spectra of the heterostructures.

  2. Effect of manganese doping on PIN-PMN-PT single crystals for high power applications

    Science.gov (United States)

    Sahul, Raffi

    Single crystals based on relaxor-lead titanate (relaxor-PT) solid solutions have advanced the world of piezoelectric materials for the past two decades with their giant piezoelectric properties achieved by domain engineered configurations. When single crystals of lead magnesium niobate-lead titanate (PMN-PT) solid solution in the rhombohedral phase were poled along [001]c direction with "4R" domain configuration, they exhibited high piezoelectric charge coefficient (d33 >2000 pC/N) and high electromechanical coupling (k33 >0.9) which led to their widespread use in advanced medical imaging systems and underwater acoustic devices. However, PMN-PT crystals suffer from low phase transition temperature (Trt ˜85-95 °C) and lower coercive field (depolarizing electric field, Ec ˜2-3 kV/cm). Lead indium niobate - lead magnesium niobate - lead titanate (PIN-PMN-PT) ternary single crystals formed by adding indium as another constituent exhibit higher coercive field (E c ˜5kV/cm) and higher Curie temperature (Tc >210 °C) than the binary PMN-PT crystals (Ec ˜2.5 kV/cm and Tc high mechanical Q-factor (Qm >600) compared to the undoped binary crystals (Qm of PMN-PT 2000 pC/N for PMN-PT) occurs in the [001]c poled crystals, which is attributed to the polarization rotation mechanisms. Hence, domain engineering configurations induced by poling these crystals in orientations other than their polarization axis are critical for achieving large piezoelectric effects. Based on the phase diagram of these solid solutions, with the increase in PT content beyond the rhombohedral phase region, orthorhombic/monoclinic and tetragonal phases are formed. In the orthorhombic and tetragonal phases, the spontaneous polarization directions are in the [011]c and [001] c directions respectively. Similar to the "4R" domain configuration achieved in [001]c poled rhombohedral crystals, other domain configurations can be achieved by poling the single crystals in different orientations, leading to

  3. Electrooptic and piezoelectric measurements in photorefractive barium titanate and strontium barium niobate

    International Nuclear Information System (INIS)

    Ducharme, S.; Feinberg, J.; Neurgaonkar, R.R.

    1987-01-01

    The authors measured the low-frequency (''unclamped'') electrooptic and piezoelectric coefficients in undoped BaTiO/sub 3/ and Sr/sub x/Ba/sub 1-x/Nb/sub 2/O/sub 6/ (chi - 0.61) crystals using interferometric techniques. The contribution of the piezoelectric effect to the Pockels measurement is discussed. For an applied ac electric field in the range 0.1-200 V/cm, the electrooptic and piezoelectric effects are linear in the magnitude of of the applied field and independent of its frequency in the range of 10 Hz-100 kHz. The unclamped electrooptic coefficients of poled BaTiO/sub 3/ single crystals are r/sub 13/ = 19.5 +- 1 pm/V and r/sub 33/ = 97 +- 7 pm/V, and for strontium barium niobate are r/sub 13/ = 47 +- 5 pm/V and r/sub 33/ = 235 +- 21 pm/V, all measured at a wavelength of 514.5 nm and at T = 23 0 C. For the barium titanate samples the measured Pockels coefficient r/sub c/ identical to r/sub 33/ - (n/sub 1//n/sub 3/)/sup 3/r/sub 13/ = 79 +- 6 pm/V in good agreement with the value r/sub c/ = 76 +- 7 pm/V computed from the above values of r/sub 13/ and r/sub 33/, where n/sub 1/ and n/sub 3/ are the ordinary and extraordinary indexes of refraction, respectively. The measured piezoelectric coefficient is d/sub 23/ = +28.7 +- 2 pm/V for barium titanate, and is d/sub 23/ = +24.6 +- 2 pm/V for strontium barium niobate. They also measured the photoreflective coupling of two optical beams in the crystals, and they show that the dependence of the coupling strength on beam polarization is in fair agreement with the measured values of the Pockels coefficients

  4. Dielectric, piezoelectric properties of MnO2-doped (K0.5Na0.5)NbO3–0.05LiNbO3 crystal grown by flux-Bridgman method

    International Nuclear Information System (INIS)

    Liu, Ying; Xu, Guisheng; Liu, Jinfeng; Yang, Danfeng; Chen, Xiaxia

    2014-01-01

    Highlights: • KNN–0.05LN based single crystals were grown by flux-Bridgman method. • Dielectric, piezoelecrc and ferroelectric properties were studied. • The effect of MnO 2 doping on the crystals' properties. • Dielectric and other properties were improved due to MnO 2 doping. - Abstract: Lead-free potassium sodium niobate piezoelectric single crystals substituted with lithium and then doped with MnO 2 (K 0.5 Na 0.5 )NbO 3 –0.05LiNbO 3 –yMnO 2 (y = 0%, 1.0% and 1.5%) (abbreviated as KNN–0.05LN–yMnO 2 ) have been grown by flux-Bridgman method using KCl–K 2 CO 3 eutectic composition as the flux. Their actual composition as well as the dielectric and piezoelectric properties were studied. Their actual composition deviated from the ratio of the raw materials due to different segregation coefficients of K and Na. The orthorhombic–tetragonal (T o–t ) and tetragonal–cubic phase transition temperature (the Curie temperature T c ) of the single crystal appears at 186 °C and 441 °C, respectively, for KNN–0.05LN–1.0%MnO 2 , shift to higher temperatures compared with that of pure KNN–0.05LN crystals, according to the dielectric permittivity versus temperature loops. The KNN–0.05LN–1.0%MnO 2 (001) plate shows higher piezoelectric coefficient d 33 and dielectric permittivity ε r when compared with pure KNN–0.05LN crystal, being on the order of 226 pC/N and 799 (161 pC/N and 530 for KNN–0.05LN), respectively. These excellent properties show that MnO 2 dopant is effective in improving KNN–0.05LN based piezoelectric crystals

  5. Synthesis of ferroelectric nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Roervik, Per Martin

    2008-12-15

    The increasing miniaturization of electric and mechanical components makes the synthesis and assembly of nanoscale structures an important step in modern technology. Functional materials, such as the ferroelectric perovskites, are vital to the integration and utility value of nanotechnology in the future. In the present work, chemical methods to synthesize one-dimensional (1D) nanostructures of ferroelectric perovskites have been studied. To successfully and controllably make 1D nanostructures by chemical methods it is very important to understand the growth mechanism of these nanostructures, in order to design the structures for use in various applications. For the integration of 1D nanostructures into devices it is also very important to be able to make arrays and large-area designed structures from the building blocks that single nanostructures constitute. As functional materials, it is of course also vital to study the properties of the nanostructures. The characterization of properties of single nanostructures is challenging, but essential to the use of such structures. The aim of this work has been to synthesize high quality single-crystalline 1D nanostructures of ferroelectric perovskites with emphasis on PbTiO3 , to make arrays or hierarchical nanostructures of 1D nanostructures on substrates, to understand the growth mechanisms of the 1D nanostructures, and to investigate the ferroelectric and piezoelectric properties of the 1D nanostructures. In Paper I, a molten salt synthesis route, previously reported to yield BaTiO3 , PbTiO3 and Na2Ti6O13 nanorods, was re-examined in order to elucidate the role of volatile chlorides. A precursor mixture containing barium (or lead) and titanium was annealed in the presence of NaCl at 760 degrees Celsius or 820 degrees Celsius. The main products were respectively isometric nanocrystalline BaTiO3 and PbTiO3. Nanorods were also detected, but electron diffraction revealed that the composition of the nanorods was

  6. High-Q photonic resonators and electro-optic coupling using silicon-on-lithium-niobate

    Science.gov (United States)

    Witmer, Jeremy D.; Valery, Joseph A.; Arrangoiz-Arriola, Patricio; Sarabalis, Christopher J.; Hill, Jeff T.; Safavi-Naeini, Amir H.

    2017-04-01

    Future quantum networks, in which superconducting quantum processors are connected via optical links, will require microwave-to-optical photon converters that preserve entanglement. A doubly-resonant electro-optic modulator (EOM) is a promising platform to realize this conversion. Here, we present our progress towards building such a modulator by demonstrating the optically-resonant half of the device. We demonstrate high quality (Q) factor ring, disk and photonic crystal resonators using a hybrid silicon-on-lithium-niobate material system. Optical Q factors up to 730,000 are achieved, corresponding to propagation loss of 0.8 dB/cm. We also use the electro-optic effect to modulate the resonance frequency of a photonic crystal cavity, achieving a electro-optic modulation coefficient between 1 and 2 pm/V. In addition to quantum technology, we expect that our results will be useful both in traditional silicon photonics applications and in high-sensitivity acousto-optic devices.

  7. Ferroelectric negative capacitance domain dynamics

    Science.gov (United States)

    Hoffmann, Michael; Khan, Asif Islam; Serrao, Claudy; Lu, Zhongyuan; Salahuddin, Sayeef; Pešić, Milan; Slesazeck, Stefan; Schroeder, Uwe; Mikolajick, Thomas

    2018-05-01

    Transient negative capacitance effects in epitaxial ferroelectric Pb(Zr0.2Ti0.8)O3 capacitors are investigated with a focus on the dynamical switching behavior governed by domain nucleation and growth. Voltage pulses are applied to a series connection of the ferroelectric capacitor and a resistor to directly measure the ferroelectric negative capacitance during switching. A time-dependent Ginzburg-Landau approach is used to investigate the underlying domain dynamics. The transient negative capacitance is shown to originate from reverse domain nucleation and unrestricted domain growth. However, with the onset of domain coalescence, the capacitance becomes positive again. The persistence of the negative capacitance state is therefore limited by the speed of domain wall motion. By changing the applied electric field, capacitor area or external resistance, this domain wall velocity can be varied predictably over several orders of magnitude. Additionally, detailed insights into the intrinsic material properties of the ferroelectric are obtainable through these measurements. A new method for reliable extraction of the average negative capacitance of the ferroelectric is presented. Furthermore, a simple analytical model is developed, which accurately describes the negative capacitance transient time as a function of the material properties and the experimental boundary conditions.

  8. Ferroelectric and incipient ferroelectric properties of a novel Sr.sub.9-x./sub.Pb.sub.x./sub.Ce.sub.2./sub.Ti.sub.12./sub.O.sub.36./sub. (x=0-9) ceramic system

    Czech Academy of Sciences Publication Activity Database

    Kamba, Stanislav; Savinov, Maxim; Laufek, F.; Tkáč, O.; Kadlec, Christelle; Veljko, Sergiy; John, E.V.; Subodh, G.; Sebastian, M. T.; Klementová, Mariana; Bovtun, Viktor; Pokorný, Jan; Goian, Veronica; Petzelt, Jan

    2009-01-01

    Roč. 21, č. 5 (2009), s. 811-819 ISSN 0897-4756 R&D Projects: GA ČR(CZ) GA202/06/0403 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectrics * crystal structure * incipient ferroelectrics * soft mode Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 5.368, year: 2009 http://pubs.acs.org/doi/abs/10.1021/cm803058q

  9. ENDOR-investigations in the environment of the ferroelectric phase transition temperature of γ-irradiated TSCC

    International Nuclear Information System (INIS)

    Welter, M.

    1983-01-01

    The structure of the CH 3 NHCH 2 COOH radical in the paraelectric phase and during the transition into the ferroelectric phase has been determined by means of ENDOR measurements. The carboxyl group of the radical is a sensitive probe for the study of crystal field changes. Structural differences of the radical between the paraelectric and the ferroelectric phase were attributed to structural changes within the nearest environment

  10. Ferroelectric inverse opals with electrically tunable photonic band gap

    International Nuclear Information System (INIS)

    Li Bo; Zhou Ji; Li Longtu; Wang Xingjun; Liu Xiaohan; Zi Jian

    2003-01-01

    We present a scheme for tuning the photonic band gap (PBG) by an external electric field in a ferroelectric inverse opal structure. The inverse opals, consisting of ferroelectric (Pb,La)(Zr,Ti)O 3 (PLZT) ceramics, were synthesized by a sol-gel process. Optical reflection spectra show that the PBG of the PLZT inverse opals shifts continuously with the change in the applied electric field. As the photonic crystals (PCs) consist of the high-refractive-index constituent and possess an 'all-solid' structure, it should supply a more reliable mode to tune the PBG by the electric field for the superprism effect in PCs. It should be of high interest in device applications

  11. Tunable multiband ferroelectric devices for reconfigurable RF-frontends

    CERN Document Server

    Zheng, Yuliang

    2013-01-01

    Reconfigurable RF-frontends aim to cope with the continuous pursuit of wider frequency coverage, higher efficiency, further compactness and lower cost of ownership. They are expected to lay the foundations of future software defined or cognitive radios. As a potential enabling technology for the frontends, the tunable ferroelectric devices have shown not only enhanced performance but also new functionalities. This book explores the recent developments in the field. It provides a cross-sectional perspective on the interdisciplinary research. With attention to the devices based on ceramic thick-films and crystal thin-films, the book reviews the adapted technologies of material synthesis, film deposition and multilayer circuitry. Next, it highlights the original classes of thin-film ferroelectric devices, including stratified metal-insulator-metal varactors with suppression of acoustic resonance and programmable bi-stable high frequency capacitors. At the end the book analyzes how the frontends can be reformed b...

  12. Manipulating the ferroelectric polarization state of BaTiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Datta, S.; Rioult, M.; Stanescu, D.; Magnan, H.; Barbier, A., E-mail: antoine.barbier@cea.fr

    2016-05-31

    Controlling the ferroelectric polarization at macroscopic or microscopic levels is crucial in the framework of the development of ferroelectric materials used in yet challenging photo-electrochemical (PEC) cells and spintronic applications. We report here on polarization methods allowing to electrically polarize prototypical samples of BaTiO{sub 3} (001) films. Epitaxial single crystalline layers were grown up to a thickness of 25 nm by atomic oxygen assisted molecular beam epitaxy on 1 at.% Nb doped SrTiO{sub 3} (001) single crystals. The samples were both microscopically and macroscopically polarized using Piezoresponse Force Microscopy and electrochemical poling in an electrolyte respectively. In addition we demonstrate the possibility to retrieve a quasi-native mixed ferroelectric polarization state after annealing. These polarization methods may be applied to many other ferroelectric thin films. - Highlights: • Ferroelectricity of BaTiO{sub 3} layers can be micro- and macroscopically controlled. • Microscopic ferroelectric domains are defined with piezoresponse force microscopy. • Poling in a LiClO{sub 4} electrolyte is a macroscopic poling method. • Air annealing above the Curie temperature “resets” the polarization state.

  13. History and the future perspective of the ferroelectric memory; Kyoyudentai memory no rekishiteki haikei to tenbo

    Energy Technology Data Exchange (ETDEWEB)

    Tarui, Y [Waseda University, Tokyo (Japan)

    1998-10-01

    Development work is in progress on ferroelectric memory. The memory is a most suitable non-volatile memory which can be incorporated into IC cards, with its higher speed, lower voltage operation, smaller power consumption, and greater number of rewriting times than EEPROM, DRAM and SRAM. Taking as an opportunity the announcement on an experiment as performed by the authors to control semiconductor charge by using electric depolarization of ferroelectric materials, reports have been made one after another on experiments on thin metal films on TGS or BaTiO3, and experiments on semiconductor films formed on ferroelectric crystals or ceramics substrates by using vacuum deposition. In order to solve problems in ferroelectric materials, thin films of PZT and PLZT have emerged, whose good hysteresis characteristics have also been reported. Thereafter, an announcement was made on a material with bismuth layer like perovskite structure. The material is characterized with having very little film fatigue degradation after rewriting of about 10 {sup 12} times. In scaling a ferroelectric memory, if voltage is decreased in proportion with the size, the operation can be reduced proportionately according to the voltage reduction. This paper introduces a method to constitute a ferroelectric memory. 22 refs., 11 figs., 2 tabs.

  14. Three-dimensional, time-resolved profiling of ferroelectric domain wall dynamics by spectral-domain optical coherence tomography

    International Nuclear Information System (INIS)

    Haussmann, Alexander; Schmidt, Sebastian; Wehmeier, Lukas; Eng, Lukas M.; Kirsten, Lars; Cimalla, Peter; Koch, Edmund

    2017-01-01

    We apply here spectral-domain optical coherence tomography (SD-OCT) for the precise detection and temporal tracking of ferroelectric domain walls (DWs) in magnesium-doped periodically poled lithium niobate (Mg:PPLN). We reproducibly map static DWs at an axial (depth) resolution down to ∝ 0.6 μm, being located up to 0.5 mm well inside the single crystalline Mg:PPLN sample. We show that a full 3-dimensional (3D) reconstruction of the DW geometry is possible from the collected data, when applying a special algorithm that accounts for the nonlinear optical dispersion of the material. Our OCT investigation provides valuable reference information on the DWs' polarization charge distribution, which is known to be the key to the electrical conductivity of ferroelectric DWs in such systems. Hence, we carefully analyze the SD-OCT signal dependence both when varying the direction of incident polarization, and when applying electrical fields along the polar axis. Surprisingly, the large backreflection intensities recorded under extraordinary polarization are not affected by any electrical field, at least for field strengths below the switching threshold, while no significant signals above noise floor are detected under ordinary polarization. Finally, we employed the high-speed SD-OCT setup for the real-time DW tracking upon ferroelectric domain switching under high external fields. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Three-dimensional, time-resolved profiling of ferroelectric domain wall dynamics by spectral-domain optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Haussmann, Alexander; Schmidt, Sebastian; Wehmeier, Lukas; Eng, Lukas M. [Technische Universitaet Dresden, Institute of Applied Physics and Center for Advancing Electronics Dresden (cfaed), Dresden (Germany); Kirsten, Lars; Cimalla, Peter; Koch, Edmund [Technische Universitaet Dresden, Faculty of Medicine Carl Gustav Carus, Anesthesiology and Intensive Care Medicine, Clinical Sensoring and Monitoring, Dresden (Germany)

    2017-08-15

    We apply here spectral-domain optical coherence tomography (SD-OCT) for the precise detection and temporal tracking of ferroelectric domain walls (DWs) in magnesium-doped periodically poled lithium niobate (Mg:PPLN). We reproducibly map static DWs at an axial (depth) resolution down to ∝ 0.6 μm, being located up to 0.5 mm well inside the single crystalline Mg:PPLN sample. We show that a full 3-dimensional (3D) reconstruction of the DW geometry is possible from the collected data, when applying a special algorithm that accounts for the nonlinear optical dispersion of the material. Our OCT investigation provides valuable reference information on the DWs' polarization charge distribution, which is known to be the key to the electrical conductivity of ferroelectric DWs in such systems. Hence, we carefully analyze the SD-OCT signal dependence both when varying the direction of incident polarization, and when applying electrical fields along the polar axis. Surprisingly, the large backreflection intensities recorded under extraordinary polarization are not affected by any electrical field, at least for field strengths below the switching threshold, while no significant signals above noise floor are detected under ordinary polarization. Finally, we employed the high-speed SD-OCT setup for the real-time DW tracking upon ferroelectric domain switching under high external fields. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. The effects of dopants on the electrical resistivity in lead magnesium niobate multilayer ceramic capacitors

    International Nuclear Information System (INIS)

    Chang, D.D.; Ling, H.C.

    1989-01-01

    Electrical resistivity studies were performed on multilayer ceramic capacitors (MLC) based on lead magnesium niobate and containing dopants of lead titanate, lead zinc niobate, and lead cobalt niobate. The results showed that lead titanate and/or lead zinc niobate had no effect on the electrical resistivity while lead cobalt niobate decreased the resistivity. In samples without lead cobalt niobate, we observed a conduction mechanism with an activation energy of --1 eV, which is commonly observed in barium titanate based dielectrics. This is attributed to ionic conduction via the motion of oxygen vacancies. The increase in conductivity (or decrease in resistivity) resulting from the addition of lead cobalt niobate was rationalized as due to electronic conduction through charge hopping among the cations. This conduction mechanism was characterized by an activation energy of --0.5 eV. Since the activation energy associated with the long-term failure was previously determined by a matrix of temperature and voltage accelerated life tests to be -- 1 eV, they conclude that conduction through charge hopping is not affecting the long-term reliability of these devices

  17. Effects of laser light confinement in periodically poled orthorhombic non-centrosymmetric Ba2NaNb5O15 crystals

    International Nuclear Information System (INIS)

    Lamela, J; Ródenas, A; Lifante, G; Jaque, D; Jaque, F; Kaminskii, A A

    2008-01-01

    In this paper we report on experimental evidence of laser light confinement between ferroelectric domains in the neodymium doped Ba 2 NaNb 5 O 15 ferroelectric crystal. High contrast near field optical microscopy images have been obtained as a consequence of the periodic modulation in the refractive index caused by the presence of 2D antiparallel ferroelectric domains

  18. Strain tunable ferroelectric and dielectric properties of BaZrO3

    International Nuclear Information System (INIS)

    Zhang, Yajun; Liu, Man; Shimada, Takahiro; Kitamura, Takayuki; Wang, Jie

    2014-01-01

    The crucial role of epitaxial (in-plane) strain on the structural, electronic, energetic, ferroelectric, and dielectric properties of BaZrO 3 (BZO) is investigated using density-functional theory calculations. We demonstrate that the BZO crystal subjected to a critical compressive (or tensile) strain exhibits non-trivial spontaneous polarization that is higher than that of well-known ferroelectrics BaTiO 3 , while the BZO crystal is essentially paraelectric in the absence of strain. The electronic structure and Born-effective-charge analyses elucidate that the strain-induced paraelectric-to-ferroelectric transition is driven by the orbital hybridization of d-p electrons between zirconium and oxygen. Through the strain-induced paraelectric-to-ferroelectric phase transition, the dielectric response of BZO is significantly enhanced by the in-plane strain. The tensile strain increases the in-plane dielectric constant by a factor of seven with respect to that without the strain, while the compression tends to enhance the out-of-plane dielectric response. Therefore, strain engineering makes BZO an important electromechanical material due to the diversity in ferroelectric and dielectric properties.

  19. Polarization retention loss in PbTiO3 ferroelectric films due to leakage currents

    NARCIS (Netherlands)

    Morelli, A.; Venkatesan, Sriram; Palasantzas, G.; Kooi, B. J.; De Hosson, J. Th. M.

    2007-01-01

    The relationship between retention loss in single crystal PbTiO3 ferroelectric thin films and leakage currents is demonstrated by piezoresponse and conductive atomic force microscopy measurements. It was found that the polarization reversal in the absence of an electric field followed a stretched

  20. Ion-beam enhanced etching for the 3D structuration of lithium niobate

    International Nuclear Information System (INIS)

    Gischkat, Thomas

    2010-01-01

    The present thesis deals with the usage of the ion-beam enhanced etching (IBEE) for the 3D structuration of lithium niobate (LiNbO 3 ).Hereby the approach of the enhancement of the wet-chemical etching rate due to the irradiation with energetic ions is pursued. This method is very success promising for the realization of micro- and nanostructures with perpendicular structural walls as well as small roughnesses. The aim of this thesis consisted therein to form the foundations for the realization of three-dimensional micro- and nanostructures (for instance: Layer systems and photonic crystals) in LiNbO 3 with high optical quality and to demonstrate on selected examples. Conditions for the success of the IBEE structuration technique is first of all the understanding of the defect formation under ion irradiation as well as the radiation-induced structure changes in the crystal and the change of the chemical resistance connected with this. For this the defect formation was studied in dependence on th ion mass, the ion energy, and the irradiation temperature. Thermally induced influences and effects on the radiation damage, as they can occur in intermediate steps in the complex processing, must be known and were studied by means of subsequent temperature treatment. The results from the defect studies were subsequently applied for the fabrication of micro- and nanostructures in LiNbO 3 . Shown is the realization of lateral structure with nearly perpendicular structure walls as well as the realization of thin membranes and slits. The subsequent combination of lateral structuration with the fabrication of thin membranes and slits allowed the three-dimensional structuration of LiNbO 3 . This is exemplarily shown for a microresonator and for a 2D photonic crystal with below lying air slit. [de

  1. Graded ferroelectrics, transpacitors and transponents

    CERN Document Server

    Mantese, Joseph V

    2005-01-01

    The text details the experimental and theoretical aspects of newly emerging ferroelectric devices, and their extensions to other ferroic systems such as: ferromagnetics, ferroelastics, piezoelectrics, etc. The theory and experimental results pertaining to non-homogeneous active ferroic devices and structures are presented.

  2. Surface Acoustic Waves in ferroelectrics

    Czech Academy of Sciences Publication Activity Database

    Tarasenko A., Nataliya; Jastrabík, Lubomír; Tarasenko, Alexander

    2004-01-01

    Roč. 298, - (2004), s. 325-333 ISSN 0015-0193 R&D Projects: GA AV ČR IBS1010203 Keywords : Rayleigh waves * ferroelectric films * phase transition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.517, year: 2004

  3. Monolithic acoustic graphene transistors based on lithium niobate thin film

    Science.gov (United States)

    Liang, J.; Liu, B.-H.; Zhang, H.-X.; Zhang, H.; Zhang, M.-L.; Zhang, D.-H.; Pang, W.

    2018-05-01

    This paper introduces an on-chip acoustic graphene transistor based on lithium niobate thin film. The graphene transistor is embedded in a microelectromechanical systems (MEMS) acoustic wave device, and surface acoustic waves generated by the resonator induce a macroscopic current in the graphene due to the acousto-electric (AE) effect. The acoustic resonator and the graphene share the lithium niobate film, and a gate voltage is applied through the back side of the silicon substrate. The AE current induced by the Rayleigh and Sezawa modes was investigated, and the transistor outputs a larger current in the Rayleigh mode because of a larger coupling to velocity ratio. The output current increases linearly with the input radiofrequency power and can be effectively modulated by the gate voltage. The acoustic graphene transistor realized a five-fold enhancement in the output current at an optimum gate voltage, outperforming its counterpart with a DC input. The acoustic graphene transistor demonstrates a paradigm for more-than-Moore technology. By combining the benefits of MEMS and graphene circuits, it opens an avenue for various system-on-chip applications.

  4. Photorefractive effects in ferroelectrics as manifestation of structural violations on mesoscales

    CERN Document Server

    Kanaev, I F

    1998-01-01

    The nature of violations in ferroelectric structures that lead to the emergence of direct photocurrents without application of external fields is discussed. We suppose that the main role in transfer processes and photovoltaic effect $9 emergence belongs to macro- and meso-scopic inhomogeneities of the crystal. The boundaries between fairly perfect crystallites have the size of several constants of the crystal lattice and strongly changes the group (pyro-, piezo-, $9 and ferroelectric) properties of the crystal. The presence of inhomogeneities and local electric fields in them determines the charge transfer mechanism: affected by light, the electrons are generated in discretely distributed defect $9 regions and transported from one inhomogeneity to another taking into account the magnitude and sign of the held. In the framework of new concepts, experimental data on recording of the shifted and nonshifted holograms in LiNbO /sub $9 3/ crystals are analyzed. (8 refs).

  5. Nanotechnology in lithium niobate for integrated optic frequency conversion in the UV

    Science.gov (United States)

    Busacca, Alessandro C.; Santini, Claudia; Oliveri, Luigi; Riva-Sanseverino, Stefano; Parisi, Antonino; Cino, Alfonso C.; Assanto, Gaetano

    2017-11-01

    In the domain of Earth Explorer satellites nanoengineered nonlinear crystals can optimize UV tunable solid-state laser converters. Lightweight sources can be based on Lithium Niobate (LN) domain engineering by electric field poling and guided wave interactions. In this Communication we report the preliminary experimental results and the very first demonstration of UltraViolet second-harmonic generation by first-order quasi-phase-matching in a surface-periodically-poled proton-exchanged LN waveguide. The pump source was a Ti-Sapphire laser with a tunability range of 700- 980 nm and a 40 GHz linewidth. We have measured UV continuous-wave light at 390 nm by means of a lock-in amplifier and of a photodiode with enhanced response in the UV. Measured conversion efficiency was about 1%W-1cm-2. QPM experiments show good agreement with theory and pave the way for a future implementation of the technique in materials less prone to photorefractive damage and wider transparency in the UV, such as Lithium Tantalate.

  6. Hybrid dual gate ferroelectric memory for multilevel information storage

    KAUST Repository

    Khan, Yasser; Caraveo-Frescas, Jesus Alfonso; Alshareef, Husam N.

    2015-01-01

    Here, we report hybrid organic/inorganic ferroelectric memory with multilevel information storage using transparent p-type SnO semiconductor and ferroelectric P(VDF-TrFE) polymer. The dual gate devices include a top ferroelectric field

  7. Ion irradiation effects on lithium niobate etalons for tunable spectral filters

    Science.gov (United States)

    Garranzo, D.; Ibarmia, S.; Alvarez-Herrero, A.; Olivares, J.; Crespillo, M.; Díaz, M.

    2017-11-01

    Solar Orbiter is a mission dedicated to solar and heliospheric physics. It was selected as the first mediumclass mission of ESA's Cosmic Vision 2015-2025 Programme. Solar Orbiter will be used to examine how the Sun creates and controls the heliosphere, the vast bubble of charged particles blown by the solar wind into the interstellar medium. One of the scientific payload elements of Solar Orbiter is the Polarimetric and Helioseismic Imager (PHI). The PHI instrument consists of two telescopes, a High Resolution Telescope (HRT) that will image a fraction of the solar disk at a resolution reaching {150 km at perihelion, and a Full Disk Telescope (FDT) to image the full solar disk during all phases of the orbit. PHI is a diffraction limited, wavelength tunable, quasi-monochromatic, polarisation sensitive imager. These capabilities are needed to infer the magnetic field and line-of-sight (LOS) velocity of the region targeted by the spacecraft. For the spectral analysis, PHI will use an order-sorting filter to isolate a bandpass of the order of 100 mÅ . The FilterGraph (FG) contains an etalon in single pass configuration as tunable spectral filter located inside a temperature stabilized oven. This filter will be made by means of a z-cut LiNbO3 crystal (about 300 microns thick) and multilayer coatings including a conductive one in order to apply a high voltage (up to 5 kV) and induce the required electric field to tune the filter. Solar Orbiter observing mission around the Sun will expose the PHI instrument to extreme radiation conditions, mainly dominated by solar high-energy particles released during severe solar events (protons with energies typically ranging from few keV up to several GeV) and the continuous isotropic background flux of galactic cosmic rays (heavy ions, from Z=1 to Z=92). The main concerns are whether the cumulated radiation damage can degrade the functionality of the filter or, in the worst case, the impact of a single highly ionizing particle

  8. Ferroelectric materials for piezoelectric actuators by optimal design

    International Nuclear Information System (INIS)

    Jayachandran, K.P.; Guedes, J.M.; Rodrigues, H.C.

    2011-01-01

    Research highlights: → Microstructure optimization of ferroelectric materials by stochastic optimization. → Polycrystalline ferroelectrics possess better piezo actuation than single crystals. → Randomness of the grain orientations would enhance the overall piezoelectricity. - Abstract: Optimization methods provide a systematic means of designing heterogeneous materials with tailored properties and microstructures focussing on a specific objective. An optimization procedure incorporating a continuum modeling is used in this work to identify the ideal orientation distribution of ferroelectrics (FEs) for application in piezoelectric actuators. Piezoelectric actuation is dictated primarily by the piezoelectric strain coefficients d iμ . Crystallographic orientation is inextricably related to the piezoelectric properties of FEs. This suggests that piezoelectric properties can be tailored by a proper choice of the parameters which control the orientation distribution. Nevertheless, this choice is complicated and it is impossible to analyze all possible combinations of the distribution parameters or the angles themselves. Stochastic optimization combined with a generalized Monte Carlo scheme is used to optimize the objective functions, the effective piezoelectric coefficients d 31 and d 15 . The procedure is applied to heterogeneous, polycrystalline, FE ceramics which are essentially an aggregate of variously oriented grains (crystallites). Global piezoelectric properties are calculated using the homogenization method at each grain configuration chosen by the optimization algorithm. Optimal design variables and microstructure that would generate polycrystalline configurations that multiply the macroscopic piezoelectricity are identified.

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

    Science.gov (United States)

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

    2012-12-01

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

  10. Relation between ferroelectric and antiferromagnetic order in RMn2O5

    International Nuclear Information System (INIS)

    Noda, Yukio; Kimura, Hiroyuki; Kamada, Youichi; Osawa, Toshihiro; Fukuda, Yosikazu; Ishikawa, Yoshihisa; Kobayashi, Satoru; Wakabayashi, Yusuke; Sawa, Hiroshi; Ikeda, Naoshi; Kohn, Kay

    2006-01-01

    RMn 2 O 5 (R=Y and rare earth) shows successive magnetic and ferroelectric phase transitions at about 45, 40, 39, 20 and 10K. We have reinvestigated the magnetic structure of YMn 2 O 5 at the commensurate phase (T=25K) using a single crystal four-circle diffractometer in order to discuss the mechanism of magnetoelectric interaction and the origin of ferroelectricity. We also observed the lattice modulation vectors (q L ) to compare the magnetic propagation vectors (q M ) by synchrotron X-ray diffraction. Improved magnetic structure data are compared with the theory recently proposed

  11. Nb 3d and O 1s core levels and chemical bonding in niobates

    International Nuclear Information System (INIS)

    Atuchin, V.V.; Kalabin, I.E.; Kesler, V.G.; Pervukhina, N.V.

    2005-01-01

    A set of available experimental data on binding energies of Nb 3d 5/2 and O 1s core levels in niobates has been observed with using energy difference (O 1s-Nb 3d 5/2 ) as a robust parameter for compound characterization. An empirical relationship between (O 1s-Nb 3d 5/2 ) values measured with XPS for Nb 5+ -niobates and mean chemical bond length L(Nb-O) has been discussed. A range of (O 1s-Nb 3d 5/2 ) values possible in Nb 5+ -niobates has been defined. An energy gap ∼1.4-1.8 eV is found between (O 1s-Nb 3d 5/2 ) values reasonable for Nb 5+ and Nb 4+ states in niobates

  12. Nb 3d and O 1s core levels and chemical bonding in niobates

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation)]. E-mail: atuchin@thermo.isp.nsc.ru; Kalabin, I.E. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Kesler, V.G. [Technical Center, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Pervukhina, N.V. [Laboratory of Crystal Chemistry, Institute of Inorganic Chemistry, SB RAS, Novosibirsk 630090 (Russian Federation)

    2005-02-01

    A set of available experimental data on binding energies of Nb 3d{sub 5/2} and O 1s core levels in niobates has been observed with using energy difference (O 1s-Nb 3d{sub 5/2}) as a robust parameter for compound characterization. An empirical relationship between (O 1s-Nb 3d{sub 5/2}) values measured with XPS for Nb{sup 5+}-niobates and mean chemical bond length L(Nb-O) has been discussed. A range of (O 1s-Nb 3d{sub 5/2}) values possible in Nb{sup 5+}-niobates has been defined. An energy gap {approx}1.4-1.8 eV is found between (O 1s-Nb 3d{sub 5/2}) values reasonable for Nb{sup 5+} and Nb{sup 4+} states in niobates.

  13. Ridge Waveguide Structures in Magnesium-Doped Lithium Niobate, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In this NASA Phase I STTR effort, the feasibility of fabricating isolated ridge waveguides in 5% magnesium-doped lithium niobate (5% MgO:LN) will be established....

  14. Structural studies of different types of ferroelectric liquid crystalline substances

    Czech Academy of Sciences Publication Activity Database

    Obadović, D.Ž.; Stojanović, M.; Bubnov, Alexej; Éber, N.; Cvetinov, M.; Vajda, A.

    2011-01-01

    Roč. 35, č. 1 (2011), s. 3-13 ISSN 1450-7404 R&D Projects: GA AV ČR IAA100100911; GA AV ČR(CZ) GA202/09/0047; GA ČR(CZ) GAP204/11/0723 Grant - others:RFASI(RU) 02.740.11.5166 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectric liquid crystals * phase transition * structure of liquid crystalline phases * molecular parameters Subject RIV: BM - Solid Matter Physics ; Magnetism

  15. Ferroelectric fluoride compositions and methods of making and using same

    Science.gov (United States)

    Halasyamani, P Shiv; Chang, Hong-Young

    2015-04-07

    A method for synthesis of a ferroelectric material characterized by the general formula A.sub.xB.sub.yF.sub.z where A is an alkaline earth metal, B is transition metal or a main group metal, x and y each range from about 1 to about 5, and z ranges from about 1 to about 20 comprising contacting an alkaline earth metal fluoride, a difluorometal compound and a fluoroorganic acid in a medium to form a reaction mixture; and subjecting the reaction mixture to conditions suitable for hydrothermal crystal growth.

  16. Recharging processes, radiation induced strain and changes of OH{sup -} bands under H{sup +} ion implantation in Ti doped lithium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, P. [Crystal Growth Centre, Anna University, Chennai 600025, Tamil Nadu (India); Moorthy Babu, S., E-mail: smoorthybabu@yahoo.co [Crystal Growth Centre, Anna University, Chennai 600025, Tamil Nadu (India); Bhaumik, I.; Ganesamoorthy, S.; Karnal, A.K. [LMDD Division, RRCAT, Indore 452013, Madhya Pradesh (India); Kumar, Praveen; Rodrigues, G.O.; Sulania, I.; Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg 110067, New Delhi (India); Pandey, A.K.; Raman, R. [Solid State Physics Laboratory, Timarpur 110 054, New Delhi (India)

    2010-01-15

    A systematic analysis of variations in structural and optical characteristics of Z-cut plates of titanium doped congruent lithium niobate single crystals implanted with 120 keV proton beam at various fluences of 10{sup 15}, 10{sup 16} and 10{sup 17} protons/cm{sup 2} is presented. Through, high resolution X-ray diffraction, atomic force microscopy, Fourier transform infrared and UV-visible-NIR analysis of congruent lithium niobate, the correlation of properties before and after implantation are discussed. HRXRD (0 0 6) reflection by Triple Crystal Mode shows that both tensile and compressive strain peak are produced by the high fluence implantation. A distinct tensile peak was observed from implanted region for a fluence of 10{sup 16} protons/cm{sup 2}. AFM micrographs indicate mountain ridges, bumps and protrusions on target surface on implantation. UV-visible-NIR spectra reveal an increase in charge transfer between Ti{sup 3+}/Ti{sup 4+} and ligand oxygen for implantation with 10{sup 15} protons/cm{sup 2}, while spectra for higher fluence implanted samples show complex absorption band in the region from 380-1100 nm. Variations of OH{sup -} stretching vibration mode were observed for cLN Pure, cLNT2% virgin, and implanted samples with FTIR spectra. The concentration of OH{sup -} ion before and after implantation was calculated from integral absorption intensity. The effect of 120 keV proton implantation induced structural, surface and optical studies were correlated.

  17. Quantum fluctuations in insulating ferroelectrics

    International Nuclear Information System (INIS)

    Riseborough, Peter S.

    2010-01-01

    Graphical abstract: It has been proposed that in a ferroelectric insulator, an applied magnetic field may couple the transverse phonon modes and produce left and right circularly polarized phonon modes which are no longer degenerate. We quantize the theory and examine the effects of quantal fluctuations. In particular, we show that the zero point fluctuations result in a large diamagnetic contribution to the magnetic susceptibility. - Abstract: It has been proposed that in a ferroelectric insulator, an applied magnetic field may couple the transverse phonon modes and produce left and right circularly polarized phonon modes which are no longer degenerate. We quantize the theory and examine the effects of quantal fluctuations. In particular, we show that the zero-point fluctuations result in a large diamagnetic contribution to the magnetic susceptibility.

  18. Fabrication and performance of porous lithium sodium potassium niobate ceramic

    Science.gov (United States)

    Chen, Caifeng; Zhu, Yuan; Ji, Jun; Cai, Feixiang; Zhang, Youming; Zhang, Ningyi; Wang, Andong

    2018-02-01

    Porous lithium sodium potassium niobate (LNK) ceramic has excellent piezoelectric properties, chemical stability and great chemical compatibility. It has a good application potential in the field of biological bone substitute. In the paper, porous LNK ceramic was fabricated with egg albumen foaming agent by foaming method. Effects of preparation process of the porous LNK ceramic on density, phase structure, hole size and piezoelectric properties were researched and characterized. The results show that the influence factors of LNK solid content and foaming agent addition are closely relevant to properties of the porous LNK ceramic. When solid content is 65% and foaming agent addition is 30%, the porous LNK ceramic has uniform holes and the best piezoelectric properties.

  19. Guest Editoria, Ferroelectrics, 323, 1

    OpenAIRE

    Krupanidhi, SB

    2005-01-01

    The Fourth Asian Meeting on Ferroelectricity (AMF-4)was organized at the Indian Institute of Science, Bangalore, INDIA during December 12–15, 2003. The organization of the conferencewas cosponsored by various agencies which included the Department of Science & Technology (DST), Defense R&D Organization (DRDO), Council of Scientific and Industrial Research (CSIR), Materials Research Society of India (MRSI), Indian Institute of Science (IISC), IEEE UFFC (USA), Taylor and Francis Scientific P...

  20. Domain wall conductivity in semiconducting hexagonal ferroelectric TbMnO3 thin films

    International Nuclear Information System (INIS)

    Kim, D J; Gruverman, A; Connell, J G; Seo, S S A

    2016-01-01

    Although enhanced conductivity of ferroelectric domain boundaries has been found in BiFeO 3 and Pb(Zr,Ti)O 3 films as well as hexagonal rare-earth manganite single crystals, the mechanism of the domain wall conductivity is still under debate. Using conductive atomic force microscopy, we observe enhanced conductance at the electrically-neutral domain walls in semiconducting hexagonal ferroelectric TbMnO 3 thin films where the structure and polarization direction are strongly constrained along the c-axis. This result indicates that domain wall conductivity in ferroelectric rare-earth manganites is not limited to charged domain walls. We show that the observed conductivity in the TbMnO 3 films is governed by a single conduction mechanism, namely, the back-to-back Schottky diodes tuned by the segregation of defects. (paper)

  1. Optically controlled electroresistance and electrically controlled photovoltage in ferroelectric tunnel junctions

    KAUST Repository

    Jin Hu, Wei; Wang, Zhihong; Yu, Weili; Wu, Tao

    2016-01-01

    Ferroelectric tunnel junctions (FTJs) have recently attracted considerable interest as a promising candidate for applications in the next-generation non-volatile memory technology. In this work, using an ultrathin (3 nm) ferroelectric Sm0.1Bi0.9FeO3 layer as the tunnelling barrier and a semiconducting Nb-doped SrTiO3 single crystal as the bottom electrode, we achieve a tunnelling electroresistance as large as 105. Furthermore, the FTJ memory states could be modulated by light illumination, which is accompanied by a hysteretic photovoltaic effect. These complimentary effects are attributed to the bias- and light-induced modulation of the tunnel barrier, both in height and width, at the semiconductor/ferroelectric interface. Overall, the highly tunable tunnelling electroresistance and the correlated photovoltaic functionalities provide a new route for producing and non-destructively sensing multiple non-volatile electronic states in such FTJs.

  2. Optically controlled electroresistance and electrically controlled photovoltage in ferroelectric tunnel junctions

    KAUST Repository

    Jin Hu, Wei

    2016-02-29

    Ferroelectric tunnel junctions (FTJs) have recently attracted considerable interest as a promising candidate for applications in the next-generation non-volatile memory technology. In this work, using an ultrathin (3 nm) ferroelectric Sm0.1Bi0.9FeO3 layer as the tunnelling barrier and a semiconducting Nb-doped SrTiO3 single crystal as the bottom electrode, we achieve a tunnelling electroresistance as large as 105. Furthermore, the FTJ memory states could be modulated by light illumination, which is accompanied by a hysteretic photovoltaic effect. These complimentary effects are attributed to the bias- and light-induced modulation of the tunnel barrier, both in height and width, at the semiconductor/ferroelectric interface. Overall, the highly tunable tunnelling electroresistance and the correlated photovoltaic functionalities provide a new route for producing and non-destructively sensing multiple non-volatile electronic states in such FTJs.

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

    Science.gov (United States)

    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.

  4. Polymer Ferroelectric Memory for Flexible Electronics

    KAUST Repository

    Khan, Mohd Adnan

    2013-11-01

    With the projected growth of the flexible and plastic electronics industry, there is renewed interest in the research community to develop high performance all-polymeric memory which will be an essential component of any electronic circuit. Some of the efforts in polymer memories are based on different mechanisms such as filamentary conduction, charge trapping effects, dipole alignment, and reduction-oxidation to name a few. Among these the leading candidate are those based on the mechanism of ferroelectricity. Polymer ferroelectric memory can be used in niche applications like smart cards, RFID tags, sensors etc. This dissertation will focus on novel material and device engineering to fabricate high performance low temperature polymeric ferroelectric memory for flexible electronics. We address and find solutions to some fundamental problems affecting all polymer ferroelectric memory like high coercive fields, fatigue and thermal stability issues, poor breakdown strength and poor p-type hole mobilities. Some of the strategies adopted in this dissertation are: Use of different flexible substrates, electrode engineering to improve charge injection and fatigue properties of ferroelectric polymers, large area ink jet printing of ferroelectric memory devices, use of polymer blends to improve insulating properties of ferroelectric polymers and use of oxide semiconductors to fabricate high mobility p-type ferroelectric memory. During the course of this dissertation we have fabricated: the first all-polymer ferroelectric capacitors with solvent modified highly conducting polymeric poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) [PEDOT:PSS] electrodes on plastic substrates with performance as good as devices with metallic Platinum-Gold electrodes on silicon substrates; the first all-polymer high performance ferroelectric memory on banknotes for security applications; novel ferroelectric capacitors based on blends of ferroelectric poly(vinylidene fluoride

  5. Polymer Ferroelectric Memory for Flexible Electronics

    KAUST Repository

    Khan, Mohd Adnan

    2013-01-01

    With the projected growth of the flexible and plastic electronics industry, there is renewed interest in the research community to develop high performance all-polymeric memory which will be an essential component of any electronic circuit. Some of the efforts in polymer memories are based on different mechanisms such as filamentary conduction, charge trapping effects, dipole alignment, and reduction-oxidation to name a few. Among these the leading candidate are those based on the mechanism of ferroelectricity. Polymer ferroelectric memory can be used in niche applications like smart cards, RFID tags, sensors etc. This dissertation will focus on novel material and device engineering to fabricate high performance low temperature polymeric ferroelectric memory for flexible electronics. We address and find solutions to some fundamental problems affecting all polymer ferroelectric memory like high coercive fields, fatigue and thermal stability issues, poor breakdown strength and poor p-type hole mobilities. Some of the strategies adopted in this dissertation are: Use of different flexible substrates, electrode engineering to improve charge injection and fatigue properties of ferroelectric polymers, large area ink jet printing of ferroelectric memory devices, use of polymer blends to improve insulating properties of ferroelectric polymers and use of oxide semiconductors to fabricate high mobility p-type ferroelectric memory. During the course of this dissertation we have fabricated: the first all-polymer ferroelectric capacitors with solvent modified highly conducting polymeric poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) [PEDOT:PSS] electrodes on plastic substrates with performance as good as devices with metallic Platinum-Gold electrodes on silicon substrates; the first all-polymer high performance ferroelectric memory on banknotes for security applications; novel ferroelectric capacitors based on blends of ferroelectric poly(vinylidene fluoride

  6. Evidence for existence of functional monoclinic phase in sodium niobate based solid solution by powder neutron diffraction

    Science.gov (United States)

    Mishra, S. K.; Jauhari, Mrinal; Mittal, R.; Krishna, P. S. R.; Reddy, V. R.; Chaplot, S. L.

    2018-04-01

    We have carried out systematic temperature-dependent neutron diffraction measurements in conjunction with dielectric spectroscopy from 6 to 300 K for sodium niobate based compounds (1-x) NaNbO3-xBaTiO3 (NNBTx). The dielectric constant is measured as a function of both temperature and frequency. It shows an anomaly at different temperatures in cooling and heating cycles and exhibits a large thermal hysteresis of ˜150 K for the composition x = 0.03. The dielectric constant is found to be dispersive in nature and suggests a relaxor ferroelectric behavior. In order to explore structural changes as a function of temperature, we analyzed the powder neutron diffraction data for the compositions x = 0.03 and 0.05. Drastic changes are observed in the powder profiles near 2θ ˜ 30.6°, 32.1°, and 34.6° in the diffraction pattern below 200 K during cooling and above 190 K in heating cycles, respectively. The disappearance of superlattice reflection and splitting in main perovskite peaks provide a signature for structural phase transition. We observed stabilization of a monoclinic phase (Cc) at low temperature. This monoclinic phase is believed to provide a flexible polarization rotation and considered to be directly linked to the high performance piezoelectricity in materials. The thermal hysteresis for composition x = 0.03 is larger than that for x = 0.05. This suggests that the addition of BaTiO3 to NaNbO3 suppresses the thermal hysteresis. It is also observed that the structural phase transition temperature decreases upon increasing the dopant concentration.

  7. Noise Analysis of Second-Harmonic Generation in Undoped and MgO-Doped Periodically Poled Lithium Niobate

    Directory of Open Access Journals (Sweden)

    Yong Wang

    2008-01-01

    Full Text Available Noise characteristics of second-harmonic generation (SHG in periodically poled lithium niobate (PPLN using the quasiphase matching (QPM technique are analyzed experimentally. In the experiment, a0.78 μm second-harmonic (SH wave was generated when a 1.56 μm fundamental wave passed through a PPLN crystal (bulk or waveguide. The time-domain and frequency-domain noise characteristics of the fundamental and SH waves were analyzed. By using the pump-probe method, the noise characteristics of SHG were further analyzed when a visible light (532 nm and an infrared light (1090 nm copropagated with the fundamental light, respectively. The noise characterizations were also investigated at different temperatures. It is found that for the bulk and waveguide PPLN crystals, the SH wave has a higher relative noise level than the corresponding fundamental wave. For the same fundamental wave, the SH wave has lower noise in a bulk crystal than in a waveguide, and in MgO-doped PPLN than in undoped PPLN. The 532 nm irradiation can lead to higher noise in PPLN than the 1090 nm irradiation. In addition, increasing temperature of device can alleviate the problem of noise in conjunction with the photorefractive effect incurred by the irradiation light. This is more significant in undoped PPLN than in MgO-doped one.

  8. Integration of first-principles methods and crystallographic database searches for new ferroelectrics: Strategies and explorations

    International Nuclear Information System (INIS)

    Bennett, Joseph W.; Rabe, Karin M.

    2012-01-01

    In this concept paper, the development of strategies for the integration of first-principles methods with crystallographic database mining for the discovery and design of novel ferroelectric materials is discussed, drawing on the results and experience derived from exploratory investigations on three different systems: (1) the double perovskite Sr(Sb 1/2 Mn 1/2 )O 3 as a candidate semiconducting ferroelectric; (2) polar derivatives of schafarzikite MSb 2 O 4 ; and (3) ferroelectric semiconductors with formula M 2 P 2 (S,Se) 6 . A variety of avenues for further research and investigation are suggested, including automated structure type classification, low-symmetry improper ferroelectrics, and high-throughput first-principles searches for additional representatives of structural families with desirable functional properties. - Graphical abstract: Integration of first-principles methods with crystallographic database mining, for the discovery and design of novel ferroelectric materials, could potentially lead to new classes of multifunctional materials. Highlights: ► Integration of first-principles methods and database mining. ► Minor structural families with desirable functional properties. ► Survey of polar entries in the Inorganic Crystal Structural Database.

  9. Retention of intermediate polarization states in ferroelectric materials enabling memories for multi-bit data storage

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dong; Asadi, Kamal; Blom, Paul W. M.; Leeuw, Dago M. de, E-mail: deleeuw@mpip-mainz.mpg.de [Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany); Katsouras, Ilias [Holst Centre, High Tech Campus 31, 5656AE Eindhoven (Netherlands); Groen, Wilhelm A. [Holst Centre, High Tech Campus 31, 5656AE Eindhoven (Netherlands); Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1 2629 HS, Delft (Netherlands)

    2016-06-06

    A homogeneous ferroelectric single crystal exhibits only two remanent polarization states that are stable over time, whereas intermediate, or unsaturated, polarization states are thermodynamically instable. Commonly used ferroelectric materials however, are inhomogeneous polycrystalline thin films or ceramics. To investigate the stability of intermediate polarization states, formed upon incomplete, or partial, switching, we have systematically studied their retention in capacitors comprising two classic ferroelectric materials, viz. random copolymer of vinylidene fluoride with trifluoroethylene, P(VDF-TrFE), and Pb(Zr,Ti)O{sub 3}. Each experiment started from a discharged and electrically depolarized ferroelectric capacitor. Voltage pulses were applied to set the given polarization states. The retention was measured as a function of time at various temperatures. The intermediate polarization states are stable over time, up to the Curie temperature. We argue that the remarkable stability originates from the coexistence of effectively independent domains, with different values of polarization and coercive field. A domain growth model is derived quantitatively describing deterministic switching between the intermediate polarization states. We show that by using well-defined voltage pulses, the polarization can be set to any arbitrary value, allowing arithmetic programming. The feasibility of arithmetic programming along with the inherent stability of intermediate polarization states makes ferroelectric materials ideal candidates for multibit data storage.

  10. Retention of intermediate polarization states in ferroelectric materials enabling memories for multi-bit data storage

    Science.gov (United States)

    Zhao, Dong; Katsouras, Ilias; Asadi, Kamal; Groen, Wilhelm A.; Blom, Paul W. M.; de Leeuw, Dago M.

    2016-06-01

    A homogeneous ferroelectric single crystal exhibits only two remanent polarization states that are stable over time, whereas intermediate, or unsaturated, polarization states are thermodynamically instable. Commonly used ferroelectric materials however, are inhomogeneous polycrystalline thin films or ceramics. To investigate the stability of intermediate polarization states, formed upon incomplete, or partial, switching, we have systematically studied their retention in capacitors comprising two classic ferroelectric materials, viz. random copolymer of vinylidene fluoride with trifluoroethylene, P(VDF-TrFE), and Pb(Zr,Ti)O3. Each experiment started from a discharged and electrically depolarized ferroelectric capacitor. Voltage pulses were applied to set the given polarization states. The retention was measured as a function of time at various temperatures. The intermediate polarization states are stable over time, up to the Curie temperature. We argue that the remarkable stability originates from the coexistence of effectively independent domains, with different values of polarization and coercive field. A domain growth model is derived quantitatively describing deterministic switching between the intermediate polarization states. We show that by using well-defined voltage pulses, the polarization can be set to any arbitrary value, allowing arithmetic programming. The feasibility of arithmetic programming along with the inherent stability of intermediate polarization states makes ferroelectric materials ideal candidates for multibit data storage.

  11. A concept of ferroelectric microparticle propulsion thruster

    International Nuclear Information System (INIS)

    Yarmolich, D.; Vekselman, V.; Krasik, Ya. E.

    2008-01-01

    A space propulsion concept using charged ferroelectric microparticles as a propellant is suggested. The measured ferroelectric plasma source thrust, produced mainly by microparticles emission, reaches ∼9x10 -4 N. The obtained trajectories of microparticles demonstrate that the majority of the microparticles are positively charged, which permits further improvement of the thruster

  12. Guided Wave Propagation in a Gold Electrode Film on a Pb(Mg1/3Nb2/3)O3−33%PbTiO3 Ferroelectric Single Crystal Substrate

    International Nuclear Information System (INIS)

    Huang Nai-Xing; LÜ Tian-Quan; Zhang Rui; Wang Yu-Ling; Cao Wen-Wu

    2014-01-01

    Dispersion relations of Love mode acoustic guided waves propagation in Pb(Mg 1/3 Nb 2/3 )O 3 −33%PbTiO 3 (PMN-0.33 PT) single crystal with a gold electrode film are calculated. There is no cross coupling among Love wave modes, which is conducive to eliminating the cross interference between modes. The general formula is derived to precisely measure the thickness of the electrode. More acoustic energy would be concentrated inside the electrode with the increase of film thickness for a given frequency. Compared with the PZT-5 ceramic, [001] c poled PMN-33%PT single crystal has a slower attenuation of the amplitude of the acoustic guided wave. Therefore, single crystal is extremely suitable for making low loss acoustic wave devices with a high operating frequency

  13. Photoelectron spectroscopic and microspectroscopic probes of ferroelectrics

    Science.gov (United States)

    Tǎnase, Liviu C.; Abramiuc, Laura E.; Teodorescu, Cristian M.

    2017-12-01

    This contribution is a review of recent aspects connected with photoelectron spectroscopy of free ferroelectric surfaces, metals interfaced with these surfaces, graphene-like layers together with some exemplifications concerning molecular adsorption, dissociations and desorptions occurring from ferroelectrics. Standard photoelectron spectroscopy is used nowadays in correlation with other characterization techniques, such as piezoresponse force microscopy, high resolution transmission electron spectroscopy, and ferroelectric hysteresis cycles. In this work we will concentrate mainly on photoelectron spectroscopy and spectro-microscopy characterization of ferroelectric thin films, starting from atomically clean ferroelectric surfaces of lead zirco-titanate, then going towards heterostructures using this material in combination with graphene-like carbon layers or with metals. Concepts involving charge accumulation and depolarization near surface will be revisited by taking into account the newest findings in this area.

  14. Ferroelectric Electron Emission Principles and Technology

    CERN Document Server

    Riege, H

    1997-01-01

    The spontaneous electrical polarization of ferroelectric materials can be changed either by reversal or by phase transition from a ferroelectric into a non-ferroelectric state or vice versa. If spontaneous polarization changes are induced with fast heat, mechanical pressure, laser or electric field pulses on a submicrosecond time scale, strong uncompensated surface charge densities and related polarization fields are generated, which may lead to the intense self-emission of electrons from the negatively charged free surface areas of the ferroelectric sample. Hence, electron guns can be built with extraction-field-free ferroelectric cathodes, which may be easily separated from the high-field regions of post-accelerating gap structures. The intensity, the energy, the temporal and spatial distribution, and the repetitition rate of the emitted electron beams can be controlled within wide limits via the excitation pulses and external focusing and accelerating electromagnetic fields. The technological advantages an...

  15. Comparative study of 0° X-cut and Y + 36°-cut lithium niobate high-voltage sensing

    Science.gov (United States)

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

    2015-08-01

    A comparison study between Y + 36° and 0° X-cut lithium niobate (LiNbO3) was performed to evaluate the influence of crystal cut on the acoustic propagation to realize a piezoelectric high-voltage sensor. The acoustic time-of-flight for each crystal cut was measured when applying direct current (DC), alternating current (AC), and pulsed voltages. Results show that the voltage-induced shift in the acoustic wave propagation time scaled quadratically with voltage for DC and AC voltages applied to X-cut crystals. For the Y + 36° crystal, the voltage-induced shift scales linearly with DC voltages and quadratically with AC voltages. When applying 5 μs voltage pulses to both crystals, the voltage-induced shift scaled linearly with voltage. For the Y + 36° cut, the voltage-induced shift from applying DC voltages ranged from 10 to 54 ps and 35 to 778 ps for AC voltages at 640 V over the frequency range of 100 Hz-100 kHz. Using the same conditions as the Y + 36° cut, the 0° X-cut crystal sensed a shift of 10-273 ps for DC voltages and 189-813 ps for AC voltage application. For 5 μs voltage pulses, the 0° X-cut crystal sensed a voltage induced shift of 0.250-2 ns and the Y + 36°-cut crystal sensed a time shift of 0.115-1.6 ns. This suggests a frequency sensitive response to voltage where the influence of the crystal cut was not a significant contributor under DC, AC, or pulsed voltage conditions. The measured DC data were compared to a 1-D impedance matrix model where the predicted incremental length changed as a function of voltage. When the voltage source error was eliminated through physical modeling from the uncertainty budget, the combined uncertainty of the sensor (within a 95% confidence interval) decreased to 0.0033% using a Y + 36°-cut crystal and 0.0032% using an X-cut crystal for all the voltage conditions used in this experiment.

  16. Comparative study of 0° X-cut and Y + 36°-cut lithium niobate high-voltage sensing

    International Nuclear Information System (INIS)

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

    2015-01-01

    A comparison study between Y + 36° and 0° X-cut lithium niobate (LiNbO 3 ) was performed to evaluate the influence of crystal cut on the acoustic propagation to realize a piezoelectric high-voltage sensor. The acoustic time-of-flight for each crystal cut was measured when applying direct current (DC), alternating current (AC), and pulsed voltages. Results show that the voltage-induced shift in the acoustic wave propagation time scaled quadratically with voltage for DC and AC voltages applied to X-cut crystals. For the Y + 36° crystal, the voltage-induced shift scales linearly with DC voltages and quadratically with AC voltages. When applying 5 μs voltage pulses to both crystals, the voltage-induced shift scaled linearly with voltage. For the Y + 36° cut, the voltage-induced shift from applying DC voltages ranged from 10 to 54 ps and 35 to 778 ps for AC voltages at 640 V over the frequency range of 100 Hz–100 kHz. Using the same conditions as the Y + 36° cut, the 0° X-cut crystal sensed a shift of 10–273 ps for DC voltages and 189–813 ps for AC voltage application. For 5 μs voltage pulses, the 0° X-cut crystal sensed a voltage induced shift of 0.250–2 ns and the Y + 36°-cut crystal sensed a time shift of 0.115–1.6 ns. This suggests a frequency sensitive response to voltage where the influence of the crystal cut was not a significant contributor under DC, AC, or pulsed voltage conditions. The measured DC data were compared to a 1-D impedance matrix model where the predicted incremental length changed as a function of voltage. When the voltage source error was eliminated through physical modeling from the uncertainty budget, the combined uncertainty of the sensor (within a 95% confidence interval) decreased to 0.0033% using a Y + 36°-cut crystal and 0.0032% using an X-cut crystal for all the voltage conditions used in this experiment

  17. Kinetics of Domain Switching by Mechanical and Electrical Stimulation in Relaxor-Based Ferroelectrics

    Science.gov (United States)

    Chen, Zibin; Hong, Liang; Wang, Feifei; An, Xianghai; Wang, Xiaolin; Ringer, Simon; Chen, Long-Qing; Luo, Haosu; Liao, Xiaozhou

    2017-12-01

    Ferroelectric materials have been extensively explored for applications in high-density nonvolatile memory devices because of their ferroelectric-ferroelastic domain-switching behavior under electric loading or mechanical stress. However, the existence of ferroelectric and ferroelastic backswitching would cause significant data loss, which affects the reliability of data storage. Here, we apply in situ transmission electron microscopy and phase-field modeling to explore the unique ferroelastic domain-switching kinetics and the origin of this in relaxor-based Pb (Mg1 /3Nb2 /3)O3-33 % PbTiO3 single-crystal pillars under electrical and mechanical stimulations. Results showed that the electric-mechanical hysteresis loop shifted for relaxor-based single-crystal pillars because of the low energy levels of domains in the material and the constraint on the pillars, resulting in various mechanically reversible and irreversible domain-switching states. The phenomenon can potentially be used for advanced bit writing and reading in nonvolatile memories, which effectively overcomes the backswitching problem and broadens the types of ferroelectric materials for nonvolatile memory applications.

  18. Nanoscale mechanical switching of ferroelectric polarization via flexoelectricity

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Yijia; Hong, Zijian; Britson, Jason; Chen, Long-Qing [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-01-12

    Flexoelectric coefficient is a fourth-rank tensor arising from the coupling between strain gradient and electric polarization and thus exists in all crystals. It is generally ignored for macroscopic crystals due to its small magnitude. However, at the nanoscale, flexoelectric contributions may become significant and can potentially be utilized for device applications. Using the phase-field method, we study the mechanical switching of electric polarization in ferroelectric thin films by a strain gradient created via an atomic force microscope tip. Our simulation results show good agreement with existing experimental observations. We examine the competition between the piezoelectric and flexoelectric effects and provide an understanding of the role of flexoelectricity in the polarization switching. Also, by changing the pressure and film thickness, we reveal that the flexoelectric field at the film bottom can be used as a criterion to determine whether domain switching may happen under a mechanical force.

  19. Chemical Synthesis of Porous Barium Titanate Thin Film and Thermal Stabilization of Ferroelectric Phase by Porosity-Induced Strain.

    Science.gov (United States)

    Suzuki, Norihiro; Osada, Minoru; Billah, Motasim; Bando, Yoshio; Yamauchi, Yusuke; Hossain, Shahriar A

    2018-03-27

    Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its well-balanced ferroelectricity, piezoelectricity, and dielectric constant. In addition, BT does not contain any toxic elements. Therefore, it is considered to be an eco-friendly material, which has attracted considerable interest as a replacement for lead zirconate titanate (PZT). However, bulk BT loses its ferroelectricity at approximately 130 °C, thus, it cannot be used at high temperatures. Because of the growing demand for high-temperature ferroelectric materials, it is important to enhance the thermal stability of ferroelectricity in BT. In previous studies, strain originating from the lattice mismatch at hetero-interfaces has been used. However, the sample preparation in this approach requires complicated and expensive physical processes, which are undesirable for practical applications. In this study, we propose a chemical synthesis of a porous material as an alternative means of introducing strain. We synthesized a porous BT thin film using a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles were used as an organic template. Through a series of studies, we clarified that the introduction of pores had a similar effect on distorting the BT crystal lattice, to that of a hetero-interface, leading to the enhancement and stabilization of ferroelectricity. Owing to its simplicity and cost effectiveness, this fabrication process has considerable advantages over conventional methods.

  20. Alloying in an Intercalation Host: Metal Titanium Niobates as Anodes for Rechargeable Alkali-Ion Batteries.

    Science.gov (United States)

    Das, Suman; Swain, Diptikanta; Araujo, Rafael B; Shi, Songxin; Ahuja, Rajeev; Row, Tayur N Guru; Bhattacharyya, Aninda J

    2018-02-02

    We discuss here a unique flexible non-carbonaceous layered host, namely, metal titanium niobates (M-Ti-niobate, M: Al 3+ , Pb 2+ , Sb 3+ , Ba 2+ , Mg 2+ ), which can synergistically store both lithium ions and sodium ions via a simultaneous intercalation and alloying mechanisms. M-Ti-niobate is formed by ion exchange of the K + ions, which are specifically located inside galleries between the layers formed by edge and corner sharing TiO 6 and NbO 6 octahedral units in the sol-gel synthesized potassium titanium niobate (KTiNbO 5 ). Drastic volume changes (approximately 300-400 %) typically associated with an alloying mechanism of storage are completely tackled chemically by the unique chemical composition and structure of the M-Ti-niobates. The free space between the adjustable Ti/Nb octahedral layers easily accommodates the volume changes. Due to the presence of an optimum amount of multivalent alloying metal ions (50-75 % of total K + ) in the M-Ti-niobate, an efficient alloying reaction takes place directly with ions and completely eliminates any form of mechanical degradation of the electroactive particles. The M-Ti-niobate can be cycled over a wide voltage range (as low as 0.01 V) and displays remarkably stable Li + and Na + ion cyclability (>2 Li + /Na + per formula unit) for widely varying current densities over few hundreds to thousands of successive cycles. The simultaneous intercalation and alloying storage mechanisms is also studied within the density functional theory (DFT) framework. DFT expectedly shows a very small variation in the volume of Al-titanium niobate following lithium alloying. Moreover, the theoretical investigations also conclusively support the occurrence of the alloying process of Li ions with the Al ions along with the intercalation process during discharge. The M-Ti-niobates studied here demonstrate a paradigm shift in chemical design of electrodes and will pave the way for the development of a multitude of improved electrodes

  1. High-temperature thermal conductivity of uranium chromite and uranium niobate

    International Nuclear Information System (INIS)

    Fedoseev, D.V.; Varshavskaya, I.G.; Lavrent'ev, A.V.; Oziraner, S.N.; Kuznetsova, D.G.

    1979-01-01

    The technique of determining thermal conductivity coefficient of uranium niobate and uranium chromite on heating with laser radiation is described. Determined is the coefficient of free-convective heat transfer (with provision for a conduction component) by means of a standard specimen. The thermal conductivity coefficients of uranium chromite and niobate were measured in the 1300-1700 K temperature range. The results are presented in a diagram form. It has been calculated, that the thermal conductivity coefficient for uranium niobate specimens is greater in comparison with uranium chromite specimens. The thermal conductivity coefficients of the materials mentioned depend on temperature very slightly. Thermal conductivity of the materials considerably depends on their porosity. The specimens under investigation were fabricated by the pressing method and had the following porosity: uranium chromite - 30 %, uranium niobate - 10 %. Calculation results show, that thermal conductivity of dense uranium chromite is higher than thermal conductivity of dense uranium niobate. The experimental error equals approximately 20 %, that is mainly due to the error of measuring the temperature equal to +-25 deg, with a micropyrometer

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    Samples of undoped yttrium and gadolinium tantalo-niobates with common formulae RE(Nb x Ta 1−x )O 4 , 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 GdNb 0.2 Ta 0.8 O 4 showed the light output around 13 times larger than PbWO 4 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. -- Highlights: •Structural, optical and scintillation properties of the rare earth tantalo-niobates were studied. •Light output shows about gradual increase with Nb content in GdTa x Nb 1−x O 4 . •Light output increases by 2–7 times relatively to yttrium tantalate and niobate in YTa x Nb 1−x O 4 . •GdTa 0.8 Nb 0.2 O 4 demonstrates the most promising scintillation parameters

  3. Irradiation-induced modification of the material parameters in magnesium-doped lithium niobate; Bestrahlungsinduzierte Modifikation der Materialparameter in Magnesiumdotiertem Lithiumniobat

    Energy Technology Data Exchange (ETDEWEB)

    Jentjens, Lena

    2010-07-01

    In the framework of this thesis the material properties of lithium niobate are directedly influenced by the irradiation with {sup 3}He ions with an energy of 40 MeV. In the first part the irradiation-induced material changes are intensively studied. Long-time stable changes of the refractive index are measured in the range of up to 6.10{sup -3}, which depend on the radiation dose and exhibit until now no saturation behaviour. Accompanied is this change by an also dose-dependent deformation as well as a brownish change of color of the crystals. Furthermore a by several orders of magnitude increased electrical dark- and photoconductivity, which depends on the ion dose and exhibits until now also no saturation behaviour. An effect independent on the ion dose is the reduction of the coercive field strength by about 10%. Furthermore it was stated the quantity of the effects not only depends on the absolute dose, but also on the irradiation direction in view of the crystallographic c-axis. The second part of this thesis deals with the generation of microscopic structures in lithium niobate. By an ion microbeam respectively a shiftable slit aperture the fabrication of refractive-index gratings is pursued. Grating with periodicity lengths in the range of 12-160 {mu}m could until now be detected and promise in comparison with photorefractive gratings the advance of larger stability.

  4. Inelastic light scattering in crystals

    Science.gov (United States)

    Sushchinskii, M. M.

    The papers presented in this volume are concerned with a variety of problems in optics and solid state physics, such as Raman scattering of light in crystals and disperse media, Rayleigh and inelastic scattering during phase transitions, characteristics of ferroelectrics in relation to the general soft mode concept, and inelastic spectral opalescence. A group-theory approach is used to classify the vibrational spectra of the crystal lattice and to analyze the properties of idealized crystal models. Particular attention is given to surface vibrational states and to the study of the surface layers of crystals and films by light scattering methods.

  5. Structural Consequences of Ferroelectric Nanolithography

    Energy Technology Data Exchange (ETDEWEB)

    J Young Jo; P Chen; R Sichel; S Bake; R Smith; N Balke; S Kalinin; M Holt; J Maser; et al.

    2011-12-31

    Domains of remnant polarization can be written into ferroelectrics with nanoscale precision using scanning probe nanolithography techniques such as piezoresponse force microscopy (PFM). Understanding the structural effects accompanying this process has been challenging due to the lack of appropriate structural characterization tools. Synchrotron X-ray nanodiffraction provides images of the domain structure written by PFM into an epitaxial Pb(Zr,Ti)O{sub 3} thin film and simultaneously reveals structural effects arising from the writing process. A coherent scattering simulation including the superposition of the beams simultaneously diffracted by multiple mosaic blocks provides an excellent fit to the observed diffraction patterns. Domains in which the polarization is reversed from the as-grown state have a strain of up to 0.1% representing the piezoelectric response to unscreened surface charges. An additional X-ray microdiffraction study of the photon-energy dependence of the difference in diffracted intensity between opposite polarization states shows that this contrast has a crystallographic origin. The sign and magnitude of the intensity contrast between domains of opposite polarization are consistent with the polarization expected from PFM images and with the writing of domains through the entire thickness of the ferroelectric layer. The strain induced by writing provides a significant additional contribution to the increased free energy of the written domain state with respect to a uniformly polarized state.

  6. CW frequency doubling of 1029 nm radiation using single pass bulk and waveguide PPLN crystals

    Czech Academy of Sciences Publication Activity Database

    Chiodo, N.; Du Burck, F.; Hrabina, Jan; Candela, Y.; Wallerand, J. P.; Acef, O.

    2013-01-01

    Roč. 311, 15 January (2013), s. 239-244 ISSN 0030-4018 R&D Projects: GA ČR GPP102/11/P820 Institutional support: RVO:68081731 Keywords : IR laser * second harmonic generation * waveguide and bulk crystals * periodically poled lithium niobate * 1029 nm wavelength Subject RIV: BH - Optics , Masers, Lasers Impact factor: 1.542, year: 2013

  7. Chemical segregation and self polarisation in ferroelectrics

    Directory of Open Access Journals (Sweden)

    Bernard E. Watts

    2009-06-01

    Full Text Available Chemical partitioning or segregation is commonly encountered in solid-state syntheses. It is driven by compositional, thermal and electric field gradients. These phenomena can be quite extreme in thin films and lead to notable effects on the electrical properties of ferroelectrics. The segregation in ferroelectric thin films will be illustrated and the mechanisms explained in terms of diffusion processes driven by a potential gradient of the oxygen. The hypothesis can also explain self polarisation and imprint in ferroelectric hysteresis.

  8. Probing nanoscale ferroelectricity by ultraviolet Raman spectroscopy.

    Science.gov (United States)

    Tenne, D A; Bruchhausen, A; Lanzillotti-Kimura, N D; Fainstein, A; Katiyar, R S; Cantarero, A; Soukiassian, A; Vaithyanathan, V; Haeni, J H; Tian, W; Schlom, D G; Choi, K J; Kim, D M; Eom, C B; Sun, H P; Pan, X Q; Li, Y L; Chen, L Q; Jia, Q X; Nakhmanson, S M; Rabe, K M; Xi, X X

    2006-09-15

    We demonstrated that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature (Tc) in ferroelectric ultrathin films and superlattices. We showed that one-unit-cell-thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are not only ferroelectric (with Tc as high as 250 kelvin) but also polarize the quantum paraelectric SrTiO3 layers adjacent to them. Tc was tuned by approximately 500 kelvin by varying the thicknesses of the BaTiO3 and SrTiO3 layers, revealing the essential roles of electrical and mechanical boundary conditions for nanoscale ferroelectricity.

  9. Static Characteristics of the Ferroelectric Transistor Inverter

    Science.gov (United States)

    Mitchell, Cody; Laws, crystal; MacLeond, Todd C.; Ho, Fat D.

    2010-01-01

    The inverter is one of the most fundamental building blocks of digital logic, and it can be used as the foundation for understanding more complex logic gates and circuits. This paper presents the characteristics of an inverter circuit using a ferroelectric field-effect transistor. The voltage transfer characteristics are analyzed with respect to varying parameters such as supply voltage, input voltage, and load resistance. The effects of the ferroelectric layer between the gate and semiconductor are examined, and comparisons are made between the inverters using ferroelectric transistors and those using traditional MOSFETs.

  10. Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

    Energy Technology Data Exchange (ETDEWEB)

    Daranciang, Dan

    2012-02-15

    We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond timescales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screening currents, associated with the displacement of electrons first antiparallel to and then parallel to the ferroelectric polarization direction.

  11. Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

    International Nuclear Information System (INIS)

    Daranciang, Dan

    2012-01-01

    We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond timescales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screening currents, associated with the displacement of electrons first antiparallel to and then parallel to the ferroelectric polarization direction.

  12. Gold particle formation via photoenhanced deposition on lithium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Zaniewski, A.M., E-mail: azaniews@asu.edu; Meeks, V.; Nemanich, R.J.

    2017-05-31

    Highlights: • Gold chloride is reduced into solid gold nanoparticles at the surface of a polarized semiconductor. • Reduction processes are driven by ultraviolet light. • Gold nanoparticle and silver nanoparticle deposition patterns are compared. - Abstract: In this work, we report on a technique to reduce gold chloride into sub-micron particles and nanoparticles. We use photoelectron transfer from periodically polarized lithium niobate (PPLN) illuminated with above band gap light to drive the surface reactions required for the reduction and particle formation. The particle sizes and distributions on the PPLN surface are sensitive to the solution concentration, with inhibited nucleation and large particles (>150 nm) for both low (2E−8M to 9E−7M) and high (1E−5M to 1E−3M) concentrations of gold chloride. At midrange values of the concentration, nucleation is more frequent, resulting in smaller sized particles (<150 nm). We compare the deposition process to that for silver, which has been previously studied. We find that the reduction of gold chloride into nanoparticles is inhibited compared to silver ion reduction, due to the multi-step reaction required for gold particle formation. This also has consequences for the resulting deposition patterns: while silver deposits into nanowires along boundaries between areas with opposite signed polarizations, such patterning of the deposition is not observed for gold, for a wide range of concentrations studied (2E−8 to 1E−3M).

  13. An EPR investigation of room temperature radiation damage and molecular motion in the ferroelectric phosphates

    International Nuclear Information System (INIS)

    Dalal, N.S.; Herak, J.N.; McDowell, C.A.

    1976-01-01

    Several types of paramagnetic centers have been detected in the room temperature irradiated KH 2 PO 4 , KD 2 PO 4 , KH 2 PO 4 -KH 2 AsO 4 , KD 2 PO 4 -KD 2 AsO 4 and in the newly discovered ferroelectric NaTh 2 (PO 4 ) 3 . Comparative studies of temperature dependence in the EPR spectra show that as in KH 2 PO 4 -type crystals, the ferroelectric phase transition in NaTh 2 (PO 4 ) 3 crystals also seems to be related to the motion of the PO 4 units. The results help to clarify some earlier observed anomalies on the effects of γ-irradiation on dielectric properties of KH 2 PO 4 and in particular, show that the extent of the damage can be controlled by changing the impurity content of the unirradiated samples. (Auth.)

  14. Laser generated soliton waveguides in photorefractive crystals

    International Nuclear Information System (INIS)

    Vlad, V.I.; Fazio, E.; Bertolotti, M.; Bosco, A.; Petris, A.

    2005-01-01

    Non-linear photo-excited processes using the photorefractive effect are revisited with emphasis on spatial soliton generation in special laser beam propagation conditions. The soliton beams can create reversible or irreversible single-mode waveguides in the propagating materials. The important features are the 3D orientation and graded index profile matched to the laser fundamental mode. Bright spatial solitons are theoretically demonstrated and experimentally observed for the propagation of c.w. and pulsed femtosecond laser beams in photorefractive materials such as Bi 12 SiO 20 (BSO) and lithium niobate crystals. Applications in high coupling efficiency, adaptive optical interconnections and photonic crystal production are possible

  15. Development of “fragility” in relaxor ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi-zhen, E-mail: wangyizhen80@gmail.com [College of Physics and Electronic Engineering, Hainan Normal University, Haikou 571158 (China); Bioengineering Program and Mechanical Engineering and Mechanics Department, Lehigh University, 19 Memorial Drive West, Bethlehem, Pennsylvania 18015 (United States); State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Chen, Lan; Xiong, Xiao-min; Zhang, Jin-xiu [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Wang, Hai-yan [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Guangzhou Institute of Measurement and Testing Technology, Guangzhou 510663 (China); Frank Zhang, X. [Bioengineering Program and Mechanical Engineering and Mechanics Department, Lehigh University, 19 Memorial Drive West, Bethlehem, Pennsylvania 18015 (United States); Fu, Jun [College of Physics and Electronic Engineering, Hainan Normal University, Haikou 571158 (China)

    2014-02-07

    Relaxor ferroelectrics (RFs), a special class of the disordered crystals or ceramics, exhibit a pronounced slowdown of their dynamics upon cooling as glass-forming liquids, called the “Super-Arrhenius (SA)” relaxation. Despite great progress in glass-forming liquids, the “fragility” property of the SA relaxation in RFs remains unclear so far. By measuring the temperature-dependent dielectric relaxation in the typical relaxor Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-x%PbTiO{sub 3} (PMN − x%PT) with 0 ≤ x ≤ 20.0, we in-depth study the “fragility” properties of the SA relaxation in PMN − x%PT. Such fascinating issues as the mechanism of the “fragility” at an atomic scale, the roles of the systematic configurational entropy change and interaction among relaxing units (RUs, including polar nanoregions and free dipoles) and the relation between “fragility” and ferroelectric order are investigated. Our results show that both the “fragility” of the temperature-dependent SA relaxation and ferroelectric order in the PMN − x%PT systems investigated arise thermodynamically from the configurational-entropy loss due to the attractive interaction among RUs, and develops as a power law, possibly diverging at the finite critical temperature T{sub c}. A reasonable physical scenario, based on our “configurational-entropy-loss” theory and Nowick's “stress-induced-ordering” theory, was proposed.

  16. Development of “fragility” in relaxor ferroelectrics

    International Nuclear Information System (INIS)

    Wang, Yi-zhen; Chen, Lan; Xiong, Xiao-min; Zhang, Jin-xiu; Wang, Hai-yan; Frank Zhang, X.; Fu, Jun

    2014-01-01

    Relaxor ferroelectrics (RFs), a special class of the disordered crystals or ceramics, exhibit a pronounced slowdown of their dynamics upon cooling as glass-forming liquids, called the “Super-Arrhenius (SA)” relaxation. Despite great progress in glass-forming liquids, the “fragility” property of the SA relaxation in RFs remains unclear so far. By measuring the temperature-dependent dielectric relaxation in the typical relaxor Pb(Mg 1/3 Nb 2/3 )O 3 -x%PbTiO 3 (PMN − x%PT) with 0 ≤ x ≤ 20.0, we in-depth study the “fragility” properties of the SA relaxation in PMN − x%PT. Such fascinating issues as the mechanism of the “fragility” at an atomic scale, the roles of the systematic configurational entropy change and interaction among relaxing units (RUs, including polar nanoregions and free dipoles) and the relation between “fragility” and ferroelectric order are investigated. Our results show that both the “fragility” of the temperature-dependent SA relaxation and ferroelectric order in the PMN − x%PT systems investigated arise thermodynamically from the configurational-entropy loss due to the attractive interaction among RUs, and develops as a power law, possibly diverging at the finite critical temperature T c . A reasonable physical scenario, based on our “configurational-entropy-loss” theory and Nowick's “stress-induced-ordering” theory, was proposed

  17. A Diagram of the Structure Evolution of Pb(Zn1/3Nb2/3 O3-9%PbTiO3 Relaxor Ferroelectric Crystals with Excellent Piezoelectric Properties

    Directory of Open Access Journals (Sweden)

    Hua Zhou

    2017-05-01

    Full Text Available Piezoelectric properties are of significant importance to medical ultrasound, actuators, sensors, and countless other device applications. The mechanism of piezoelectric properties can be deeply understood in light of structure evolutions. In this paper, we report a diagram of the structure evolutions of Pb(Zn1/3Nb2/30.91Ti0.09O3 (PZN-9PT crystals with excellent piezoelectric properties among orthorhombic, tetragonal, and cubic phases, with a temperature increasing from room temperature to 220 °C. Through fitting the temperature-dependent XRD curves with Gauss and Lorenz functions, we obtained the evolutions of the content ratio of three kinds of phases (orthorhombic, tetragonal and cubic and the lattice parameters of the PZN-9PT system with the changes of temperature. The XRD fitting results together with Raman and dielectric spectra show that the phase transitions of PZN-9PT are a typical continuous evolution process. Additionally, resonance and anti-resonance spectra show the excellent piezoelectric properties of these crystals, which probably originate from the nano twin domains, as demonstrated by TEM images. Of particular attention is that the thickness electromechanical coupling factor kt is up to 72%.

  18. Optimal design of DC-based polarization beam splitter in lithium niobate on insulator

    Science.gov (United States)

    Gong, Zisu; Yin, Rui; Ji, Wei; Wang, Junbao; Wu, Chonghao; Li, Xiao; Zhang, Shicheng

    2017-08-01

    We propose a DC-based polarization beam splitter (PBS) in lithium niobate on insulator (LNOI). Utilizing the high birefringence property of Lithium Niobate (LiNbO3, LN), the device is achieved by simple structure in a short length. With the use of beam propagation method (BPM), the simulation results show that the device has a good performance for the separation of TE and TM polarizations with a high extinction ratio (about 35 dB). The simulated fabrication tolerance for the variation of the waveguide width is about 100 nm and the bandwidth is about 65 nm when the extinction ratio is higher than 10 dB.

  19. Writing single-mode waveguides in lithium niobate by ultra-low intensity solitons

    International Nuclear Information System (INIS)

    Fazio, E.; Ramadan, W.; Petris, A.; Chauvet, M.; Bosco, A.; Vlad, V.I.; Bertolotti, M.

    2005-01-01

    Optical waveguides can be conveniently written in photorefractive materials by using spatial solitons. We have generated bright spatial solitons inside lithium niobate which allow single-mode light propagation. Efficient waveguides have been generated with CW light powers as high as few microwatts. According to the soliton formation, waveguides can be formed with different shapes. Due to the slow response time of the lithium niobate, both for soliton formation and relaxation, the soliton waveguide remains memorised for a long time, of the order of months

  20. Tunable dual-wavelength filter and its group delay dispersion in domain-engineered lithium niobate

    Directory of Open Access Journals (Sweden)

    Guang-hao Shao

    2016-12-01

    Full Text Available A tunable dual-wavelength filter is experimentally demonstrated in domain-engineered lithium niobate. Application of an electric field on the y-surfaces of the sample results in the optical axes rotating clockwise and anticlockwise, which makes selective polarization rotation. The quasi phase-matching wavelengths could be adjusted through suitable domain design. A unique dual valley spectrum is obtained in a periodically poled lithium niobate structure with a central defect if the sample is placed between two parallel polarizers. The expected bandwidth could be varied from ∼1 nm to ∼40 nm. Moreover, both the spectral response and group delay dispersion could be engineered.

  1. Modeling of Toroidal Ordering in Ferroelectric Nanodots

    National Research Council Canada - National Science Library

    Crone, Joshua C; Chung, Peter W

    2007-01-01

    .... Beginning with an introduction of basic concepts, the report reviews the current state-of-the-art of ferroelectric nanodot technology through a literature review and identifies areas of need for continued study...

  2. Negative capacitance in a ferroelectric capacitor.

    Science.gov (United States)

    Khan, Asif Islam; Chatterjee, Korok; Wang, Brian; Drapcho, Steven; You, Long; Serrao, Claudy; Bakaul, Saidur Rahman; Ramesh, Ramamoorthy; Salahuddin, Sayeef

    2015-02-01

    The Boltzmann distribution of electrons poses a fundamental barrier to lowering energy dissipation in conventional electronics, often termed as Boltzmann Tyranny. Negative capacitance in ferroelectric materials, which stems from the stored energy of a phase transition, could provide a solution, but a direct measurement of negative capacitance has so far been elusive. Here, we report the observation of negative capacitance in a thin, epitaxial ferroelectric film. When a voltage pulse is applied, the voltage across the ferroelectric capacitor is found to be decreasing with time--in exactly the opposite direction to which voltage for a regular capacitor should change. Analysis of this 'inductance'-like behaviour from a capacitor presents an unprecedented insight into the intrinsic energy profile of the ferroelectric material and could pave the way for completely new applications.

  3. Four-state ferroelectric spin-valve

    Czech Academy of Sciences Publication Activity Database

    Quindeau, A.; Fina, I.; Martí, Xavier; Apachitei, G.; Ferrer, P.; Nicklin, C.; Pippel, E.; Hesse, D.; Alexe, M.

    2015-01-01

    Roč. 5, May (2015), 09749 ISSN 2045-2322 Institutional support: RVO:68378271 Keywords : electronic and spintronic devices * ferroelectrics and multiferroics Subject RIV: BE - Theoretical Physics Impact factor: 5.228, year: 2015

  4. Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

    Science.gov (United States)

    2016-04-19

    the free energy of the system [3,4,8]. Intensive research has been aimed at bypassing the intrinsic size limits imposed by the depolarization field...Page 1 of 21   Ultrafast photovoltaic response in ferroelectric nanolayers Dan Daranciang1,2, Matthew J. Highland3, Haidan Wen4, Steve M. Young5...ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on

  5. Ferroelectric Phase Diagram of PVDF:PMMA

    OpenAIRE

    Li, Mengyuan; Stingelin, Natalie; Michels, Jasper J.; Spijkman, Mark-Jan; Asadi, Kamal; Feldman, Kirill; Blom, Paul W. M.; de Leeuw, Dago M.

    2012-01-01

    We have investigated the ferroelectric phase diagram of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA). The binary nonequilibrium temperature composition diagram was determined and melting of alpha- and beta-phase PVDF was identified. Ferroelectric beta-PVDF:PMMA blend films were made by melting, ice quenching, and subsequent annealing above the glass transition temperature of PMMA, close to the melting temperature of PVDF. Addition of PMMA suppresses the crystallizatio...

  6. Tensile strain effect in ferroelectric perovskite oxide thin films on spinel magnesium aluminum oxide substrate

    Science.gov (United States)

    Zhou, Xiaolan

    Ferroelectrics are used in FeRAM (Ferroelectric random-access memory). Currently (Pb,Zr)TiO3 is the most common ferroelectric material. To get lead-free and high performance ferroelectric material, we investigated perovskite ferroelectric oxides (Ba,Sr)TiO3 and BiFeO3 films with strain. Compressive strain has been investigated intensively, but the effects of tensile strain on the perovskite films have yet to be explored. We have deposited (Ba,Sr)TiO3, BiFeO3 and related films by pulsed laser deposition (PLD) and analyzed the films by X-ray diffractometry (XRD), atomic force microscopy (AFM), etc. To obtain inherently fully strained films, the selection of the appropriate substrates is crucial. MgAl2O4 matches best with good quality and size, yet the spinel structure has an intrinsic incompatibility to that of perovskite. We introduced a rock-salt structure material (Ni 1-xAlxO1+delta) as a buffer layer to mediate the structural mismatch for (Ba,Sr)TiO3 films. With buffer layer Ni1-xAlxO1+delta, we show that the BST films have high quality crystallization and are coherently epitaxial. AFM images show that the films have smoother surfaces when including the buffer layer, indicating an inherent compatibility between BST-NAO and NAO-MAO. In-plane Ferroelectricity measurement shows double hysteresis loops, indicating an antiferroelectric-like behavior: pinned ferroelectric domains with antiparallel alignments of polarization. The Curie temperatures of the coherent fully strained BST films are also measured. It is higher than 900°C, at least 800°C higher than that of bulk. The improved Curie temperature makes the use of BST as FeRAM feasible. We found that the special behaviors of ferroelectricity including hysteresis loop and Curie temperature are due to inherent fully tensile strain. This might be a clue of physics inside ferroelectric stain engineering. An out-of-plane ferroelectricity measurement would provide a full whole story of the tensile strain. However, a

  7. Neutron and x-ray scattering studies of ferroelectric phase transitions

    International Nuclear Information System (INIS)

    Dolling, G.

    1982-08-01

    The subject of ferroelectric type phase transitions is introduced by means of examples of two main classes (a) displacive transitions, e.g. KNbO 3 , and (b) order-disorder transitions, e.g. NaNO 2 . The significance of crystal structure and crystal dynamics (i.e. the phonon dispersion relations) for ferroelectric behaviour is emphasized. The chief methods for structure determination are x-ray and neutron diffraction, while the most powerful of all techniques for studying phonon properties is that of coherent inelastic neutron scattering. The most useful type of neutron spectrometer for phase transition studies, the triple axis crystal spectrometer, is discussed in detail. The history of the soft mode theory of displacive phase transitions, and its application to the antiferroelectric and 'almost ferroelectric' transitions in SrTiO 3 , provides an introduction to more recent developments in this area, including over-damped soft modes, central peaks and critical scattering, incommensurate phase transitions (e.g. K 2 SeO 4 ), amplitudons, phasons and finally solitions. The treatment throughout is descriptive and introductory, designed for graduate students

  8. Enhanced electrical properties in bilayered ferroelectric thin films

    Science.gov (United States)

    Zhang, Hao; Long, WeiJie; Chen, YaQing; Guo, DongJie

    2013-03-01

    Sr2Bi4Ti5O18 (SBTi) single layered and Sr2Bi4Ti5O18/Pb(Zr0.53Ti0.47)O3 (SBTi/PZT) bilayered thin films have been prepared on Pt/TiO2/SiO2/Si substrates by pulsed-laser deposition (PLD). The related structural characterizations and electrical properties have been comparatively investigated. X-ray diffraction reveals that both films have crystallized into perovskite phases and scanning electron microscopy shows the sharp interfaces. Both films show well-saturated ferroelectric hysteresis loops, however, compared with the single layered SBTi films, the SBTi/PZT bilayered films have significantly increased remnant polarization ( P r) and decreased coercive field ( E c), with the applied field of 260 kV/cm. The measured P r and E c of SBTi and SBTi/PZT films were 7.9 μC/cm2, 88.1 kV/cm and 13.0 μC/cm2, 51.2 kV/cm, respectively. In addition, both films showed good fatigue-free characteristics, the switchable polarization decreased by 9% and 11% of the initial values after 2.2×109 switching cycles for the SBTi single layered films and the SBTi/PZT bilayered films, respectively. Our results may provide some guidelines for further optimization of multilayered ferroelectric thin films.

  9. Annealing behaviour of MeV erbium implanted lithium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Gortmaker, P; McCallum, J C [Royal Melbourne Inst. of Tech., VIC (Australia)

    1994-12-31

    Lithium niobate (LiNbO{sub 3}) is a crystalline ceramic commonly used in the fabrication of optoelectronic devices. Recently, rare earth doping of LiNbO{sub 3} has become a topic of particular interest. The electronic configuration of rare earth elements such as Erbium (Er) and Neodymium (Nd) allows them to lase in nearly any host matrix making fabrication of a whole range of new optoelectronic devices possible. At present, the doping technique, for LiNbO{sub 3} are centred upon diffusion technology, but the diffusion profiles for the rare earths are not generally well-matched to the optical modes of the device. The aim of this research is to develop MeV implantation and annealing conditions of rare earth doped LiNbO{sub 3} that would be compatible with optoelectronic device fabrication. To determine the characteristics of the rare earth elements in the LiNbO{sub 3} host material over the depth range of interest in optoelectronic device applications, high energy Rutherford backscattering spectrometry and ion channeling (RBS-C) must be used. Presented here are the Er depth profile and lattice damage results obtained from 5 MeV RBS-C measurements on samples of LiNbO{sub 3} implanted with various doses of MeV Erbium and subsequently thermally annealed at a temperature of 1000 deg C. It was found that there is a peak implant concentration (2 x 10{sup 16} Er/cm{sup 2}) for which erbium no longer goes substitutional in the lattice, and the implantation damage is not fully removed by annealing. 8 refs., 3 figs.

  10. Synthesis and thermoluminescent characterization of lithium niobate doped with erbium

    International Nuclear Information System (INIS)

    Landavazo, M.; Brown, F.; Cubillas, F.; Munoz, I.; Cruz Z, E.

    2015-10-01

    Full text: Lithium niobate (Nl) is a synthetic dielectric and is mainly used in optical devices. There are reports on the thermoluminescent property of Nl monocrystals doped with rare earths and excited with X and gamma rays. In this study the Nl was synthesized and doped with erbium (Er) at concentrations of 1, 2 and 4 % mol and was characterized by its Tl property. The synthesis was realized by solid state reaction at 1000 degrees C for 22 hours and the formation of Nl:Er was confirmed by X-ray diffraction, scanning electron microscopy and EDS analysis, finding a new phase (ErNbO 4 ). Was studied the dose-response gamma in a range of 1-1000 Gy, the material showed linear behavior of 1-600 Gy. The brightness curves have maxima at 185 and 285 degrees C to 1% in 183 and 301 degrees C for 2%, respectively. While for the concentration of 4% a maximum in 177 degrees C accompanied by a smaller peak at higher temperature of the glow curve was observed. The Tl response of Nl:Er 4% to 450 Gy was increased 271 times compared to pure Nl. The reproducibility of the Tl signal at ten cycles of irradiation-reading, present a standard deviation of 5%. In Nl:Er 1% Tl signal fades in 21.3% after 24 hours, while in 2 and 4% an unusual fading occurs. The Tl characteristics of Nl:Er synthesized material is of interest to gamma radiation dosimetry of high doses. (Author)

  11. Ridge Waveguide Structures in Magnesium-Doped Lithium Niobate

    Science.gov (United States)

    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

  12. Annealing behaviour of MeV erbium implanted lithium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Gortmaker, P.; McCallum, J.C. [Royal Melbourne Inst. of Tech., VIC (Australia)

    1993-12-31

    Lithium niobate (LiNbO{sub 3}) is a crystalline ceramic commonly used in the fabrication of optoelectronic devices. Recently, rare earth doping of LiNbO{sub 3} has become a topic of particular interest. The electronic configuration of rare earth elements such as Erbium (Er) and Neodymium (Nd) allows them to lase in nearly any host matrix making fabrication of a whole range of new optoelectronic devices possible. At present, the doping technique, for LiNbO{sub 3} are centred upon diffusion technology, but the diffusion profiles for the rare earths are not generally well-matched to the optical modes of the device. The aim of this research is to develop MeV implantation and annealing conditions of rare earth doped LiNbO{sub 3} that would be compatible with optoelectronic device fabrication. To determine the characteristics of the rare earth elements in the LiNbO{sub 3} host material over the depth range of interest in optoelectronic device applications, high energy Rutherford backscattering spectrometry and ion channeling (RBS-C) must be used. Presented here are the Er depth profile and lattice damage results obtained from 5 MeV RBS-C measurements on samples of LiNbO{sub 3} implanted with various doses of MeV Erbium and subsequently thermally annealed at a temperature of 1000 deg C. It was found that there is a peak implant concentration (2 x 10{sup 16} Er/cm{sup 2}) for which erbium no longer goes substitutional in the lattice, and the implantation damage is not fully removed by annealing. 8 refs., 3 figs.

  13. Numerical analysis of continuous charge of lithium niobate in a double-crucible Czochralski system using the accelerated crucible rotation technique

    Science.gov (United States)

    Kitashima, Tomonori; Liu, Lijun; Kitamura, Kenji; Kakimoto, Koichi

    2004-05-01

    The transport mechanism of supplied raw material in a double-crucible Czochralski system using the accelerated crucible rotation technique (ACRT) was investigated by three-dimensional and time-dependent numerical simulation. The calculation clarified that use of the ACRT resulted in enhancement of the mixing effect of the supplied raw material. It is, therefore, possible to maintain the composition of the melt in an inner crucible during crystal growth by using the ACRT. The effect of the continuous charge of the raw material on melt temperature was also investigated. Our results showed that the effect of feeding lithium niobate granules on melt temperature was small, since the feeding rate of the granules is small. Therefore, solidification of the melt surface due to the heat of fusion in this system is not likely.

  14. Continuous-wave sodium D2 resonance radiation generated in single-pass sum-frequency generation with periodically poled lithium niobate.

    Science.gov (United States)

    Yue, J; She, C-Y; Williams, B P; Vance, J D; Acott, P E; Kawahara, T D

    2009-04-01

    With two cw single-mode Nd:YAG lasers at 1064 and 1319 nm and a periodically poled lithium niobate crystal, 11 mW of 2 kHz/100 ms bandwidth single-mode tunable 589 nm cw radiation has been detected using single-pass sum-frequency generation. The demonstrated conversion efficiency is approximately 3.2%[W(-1) cm(-1)]. This compact solid-state light source has been used in a solid-state-dye laser hybrid sodium fluorescence lidar transmitter to measure temperatures and winds in the upper atmosphere (80-105 km); it is being implemented into the transmitter of a mobile all-solid-state sodium temperature and wind lidar under construction.

  15. Modification of phase transitions in swift heavy ion irradiated and MMA-grafted ferroelectric fluoro-polymers

    International Nuclear Information System (INIS)

    Petersohn, E.; Betz, N.; Le Moel, A.

    1994-01-01

    Ferroelectric polyvinylidene fluoride (β) and copolymers of vinylidene fluoride trifluoroethylene (P(VDF/TrFE)) films were irradiated with swift heavy ions and post irradiation grafted with methyl methacrylate (MMA). We have studied the influence of irradiation parameters such as the ion fluence, the type of ion and the electronic stopping power, on the melting and crystallization temperatures and the ferroelectric-paraelectric phase transitions, by differential scanning calorimetry (DSC) and dielectric measurements. The relation between the shift in the transition temperatures and the ion fluence is described by a single term equation. Ion track grafting with MMA affects the ferroelectric-paraelectric phase transitions in P(VDF/TrFE) and leads to a strong amorphization of the polymer films. The grafting in β PVDF occurs mainly on the surface of the samples and no change in the transition temperatures is observed. (authors). 12 refs., 6 figs., 2 tabs

  16. A two-step annealing process for enhancing the ferroelectric properties of poly(vinylidene fluoride) (PVDF) devices

    KAUST Repository

    Park, Jihoon

    2015-01-01

    We report a simple two-step annealing scheme for the fabrication of stable non-volatile memory devices employing poly(vinylidene fluoride) (PVDF) polymer thin-films. The proposed two-step annealing scheme comprises the crystallization of the ferroelectric gamma-phase during the first step and enhancement of the PVDF film dense morphology during the second step. Moreover, when we extended the processing time of the second step, we obtained good hysteresis curves down to 1 Hz, the first such report for ferroelectric PVDF films. The PVDF films also exhibit a coercive field of 113 MV m-1 and a ferroelectric polarization of 5.4 μC cm-2. © The Royal Society of Chemistry 2015.

  17. Chemical transport of niobium(V) oxide and of lithium niobate with sulphur

    International Nuclear Information System (INIS)

    Schaefer, H.

    1988-01-01

    Niobium(V) oxide is transported by means of sulphur (calculated for 10 bar at 1223 K) from 1273 → 1173 K. The same applies for lithium niobate. Similar experiments of lithium oxide lead to turbidity of the quartz ampoule. (author)

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

    NARCIS (Netherlands)

    Wolf, S.; Rensberg, J.; Johannes, A.; Thomae, R.; Smit, F.; Neveling, R.; Moodley, M.; Bierschenk, T.; Rodriquez, M.; Afra, B.; Hasan, Shakeeb Bin; Rockstuhl, C.; Ridgway, M.; Bharuth-Ram, K.; Ronning, C.

    2016-01-01

    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

  19. All-optical switching in lithium niobate directional couplers with cascaded nonlinearity

    NARCIS (Netherlands)

    Schiek, R.; Baek, Y.; Krijnen, Gijsbertus J.M.; Stegeman, G.I.; Baumann, I.; Sohler, W.

    1996-01-01

    We report on intensity-dependent switching in lithium niobate directional couplers. Large nonlinear phase shifts that are due to cascading detune the coupling between the coupler branches, which makes all-optical switching possible. Depending on the input intensity, the output could be switched

  20. Erbium medium temperature localised doping into lithium niobate and sapphire: A comparative study

    Czech Academy of Sciences Publication Activity Database

    Nekvindová, P.; Macková, Anna; Peřina, Vratislav; Červená, Jarmila; Čapek, P.; Schrofel, J.; Špirková, J.; Oswald, Jiří

    90-91, - (2003), s. 559-564 ISSN 1012-0394 Institutional research plan: CEZ:AV0Z1048901 Keywords : lithium niobate * sapphire * erbium Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.687, year: 2003

  1. Safe disposal of radioactive iodide ions from solutions by Ag2O grafted sodium niobate nanofibers.

    Science.gov (United States)

    Mu, Wanjun; Li, Xingliang; Liu, Guoping; Yu, Qianhong; Xie, Xiang; Wei, Hongyuan; Jian, Yuan

    2016-01-14

    Radioactive iodine isotopes are released into the environment by the nuclear industry and medical research institutions using radioactive materials, and have negative effects on organisms living within the ecosystem. Thus, safe disposal of radioactive iodine is necessary and crucial. For this reason, the uptake of iodide ions was investigated in Ag2O nanocrystal grafted sodium niobate nanofibers, which were prepared by forming a well-matched phase coherent interface between them. The resulting composite was applied as an efficient adsorbent for I(-) anions by forming an AgI precipitate, which also remained firmly attached to the substrates. Due to their one-dimensional morphology, the new adsorbents can be easily dispersed in liquids and readily separated after purification. This significantly enhances the adsorption efficiency and reduces the separation costs. The change in structure from the pristine sodium niobate to Ag2O anchored sodium niobate and to the used adsorbent was examined by using various characterization techniques. The effects of Ag(+) concentration, pH, equilibration time, ionic strength and competing ions on the iodide ion removal ability of the composite were studied. The Ag2O nanocrystal grafted sodium niobate adsorbent showed a high adsorption capacity and excellent selectivity for I(-) anions in basic solutions. Our results are useful for the further development of improved adsorbents for removing I(-) anions from basic wastewater.

  2. Flexible Piezoelectric Touch Sensor by Alignment of Lead-Free Alkaline Niobate Microcubes in PDMS

    NARCIS (Netherlands)

    Deutz, D.B.; Mascarenhas, N.T.; Schelen, J.B.J.; de Leeuw, D.M.; van der Zwaag, S.; Groen, W.A.

    2017-01-01

    A highly sensitive, lead-free, and flexible piezoelectric touch sensor is reported based on composite films of alkaline niobate K0.485Na0.485Li0.03NbO3 (KNLN) powders aligned in a polydimethylsiloxane (PDMS) matrix. KNLN powder is fabricated by

  3. Enhancement of Dielectric Breakdown Strength and Energy Conversion Efficiency of Niobate Glass-Ceramics by Sc2O3 Doping

    Science.gov (United States)

    Xiao, Shi; Xiu, Shaomei; Yang, Ke; Shen, Bo; Zhai, Jiwei

    2018-01-01

    Niobate glass-ceramics K2O-SrO-Nb2O5-B2O3-Al2O3-SiO2 (KSN-BAS) doped with different amounts of Sc2O3 have been prepared through a melt quenching/controlled crystallization method, and the influence of the Sc2O3 content on their phase composition, microstructure, dielectric performance, and charge-discharge properties investigated. X-ray powder diffraction results showed that the peak positions of the KSr2Nb5O15 phase shifted to higher angle and the glass-ceramic microstructures were significantly improved by Sc2O3 addition. Based on these results, 0.5 mol.% Sc2O3 doping was found to achieve remarkable enhancement in energy storage density, which reached 9.63 ± 0.39 J/cm3 at dielectric breakdown strength of 1450.38 ± 29.01 kV/cm with high conversion efficiency of ˜ 92.1%. For pulsed power applications, discharge speed of 17 ns and power density of 0.48 MW/cm3 were obtained in the glass-ceramic with 0.5 mol.% Sc2O3. These results could provide a new design strategy for high-performance dielectric capacitors.

  4. Thermal expansion of LATGS crystals

    International Nuclear Information System (INIS)

    Kassem, M.E.; Kandil, S.H.; Hamed, A.E.; Stankowska, J.

    1989-04-01

    The thermal expansion of triglycine sulphate crystals doped with L-α alanine (LATGS) has been studied around the phase transition temperature (30-60 deg. C) using thermomechanical analysis TMA. With increasing the content of admixture, the transition temperature (T c ) was shifted towards higher values, while the relative changes in the dimension of the crystals (ΔL/L 0 ) of the studied directions varied both in the para- and ferroelectric phases. The transition width in the case of doped crystals was found to be broad, and this broadening increases with increasing the content of L-α alanine. (author). 12 refs, 3 figs

  5. Multiple-octave spanning high-energy mid-IR supercontinuum generation in bulk quadratic nonlinear crystals

    DEFF Research Database (Denmark)

    Zhou, Binbin; Bache, Morten

    2016-01-01

    Bright and broadband coherent mid-IR radiation is important for exciting and probing molecular vibrations. Using cascaded nonlinearities in conventional quadratic nonlinear crystals like lithium niobate, self-defocusing near-IR solitons have been demonstrated that led to very broadband...

  6. Organic ferroelectric/semiconducting nanowire hybrid layer for memory storage

    NARCIS (Netherlands)

    Cai, R.; Kassa, H.G.; Haouari, R.; Marrani, A.; Geerts, Y.H.; Ruzié, C.; Breemen, A.J.J.M. van; Gelinck, G.H.; Nysten, B.; Hu, Z.; Jonas, A.M.

    2016-01-01

    Ferroelectric materials are important components of sensors, actuators and non-volatile memories. However, possible device configurations are limited due to the need to provide screening charges to ferroelectric interfaces to avoid depolarization. Here we show that, by alternating ferroelectric and

  7. Flexible graphene–PZT ferroelectric nonvolatile memory

    International Nuclear Information System (INIS)

    Lee, Wonho; Ahn, Jong-Hyun; Kahya, Orhan; Toh, Chee Tat; Özyilmaz, Barbaros

    2013-01-01

    We report the fabrication of a flexible graphene-based nonvolatile memory device using Pb(Zr 0.35 ,Ti 0.65 )O 3 (PZT) as the ferroelectric material. The graphene and PZT ferroelectric layers were deposited using chemical vapor deposition and sol–gel methods, respectively. Such PZT films show a high remnant polarization (P r ) of 30 μC cm −2 and a coercive voltage (V c ) of 3.5 V under a voltage loop over ±11 V. The graphene–PZT ferroelectric nonvolatile memory on a plastic substrate displayed an on/off current ratio of 6.7, a memory window of 6 V and reliable operation. In addition, the device showed one order of magnitude lower operation voltage range than organic-based ferroelectric nonvolatile memory after removing the anti-ferroelectric behavior incorporating an electrolyte solution. The devices showed robust operation in bent states of bending radii up to 9 mm and in cycling tests of 200 times. The devices exhibited remarkable mechanical properties and were readily integrated with plastic substrates for the production of flexible circuits. (paper)

  8. Impact induced depolarization of ferroelectric materials

    Science.gov (United States)

    Agrawal, Vinamra; Bhattacharya, Kaushik

    2018-06-01

    We study the large deformation dynamic behavior and the associated nonlinear electro-thermo-mechanical coupling exhibited by ferroelectric materials in adiabatic environments. This is motivated by a ferroelectric generator which involves pulsed power generation by loading the ferroelectric material with a shock, either by impact or a blast. Upon impact, a shock wave travels through the material inducing a ferroelectric to nonpolar phase transition giving rise to a large voltage difference in an open circuit situation or a large current in a closed circuit situation. In the first part of this paper, we provide a general continuum mechanical treatment of the situation assuming a sharp phase boundary that is possibly charged. We derive the governing laws, as well as the driving force acting on the phase boundary. In the second part, we use the derived equations and a particular constitutive relation that describes the ferroelectric to nonpolar phase transition to study a uniaxial plate impact problem. We develop a numerical method where the phase boundary is tracked but other discontinuities are captured using a finite volume method. We compare our results with experimental observations to find good agreement. Specifically, our model reproduces the observed exponential rise of charge as well as the resistance dependent Hugoniot. We conclude with a parameter study that provides detailed insight into various aspects of the problem.

  9. Flexible graphene-PZT ferroelectric nonvolatile memory.

    Science.gov (United States)

    Lee, Wonho; Kahya, Orhan; Toh, Chee Tat; Ozyilmaz, Barbaros; Ahn, Jong-Hyun

    2013-11-29

    We report the fabrication of a flexible graphene-based nonvolatile memory device using Pb(Zr0.35,Ti0.65)O3 (PZT) as the ferroelectric material. The graphene and PZT ferroelectric layers were deposited using chemical vapor deposition and sol–gel methods, respectively. Such PZT films show a high remnant polarization (Pr) of 30 μC cm−2 and a coercive voltage (Vc) of 3.5 V under a voltage loop over ±11 V. The graphene–PZT ferroelectric nonvolatile memory on a plastic substrate displayed an on/off current ratio of 6.7, a memory window of 6 V and reliable operation. In addition, the device showed one order of magnitude lower operation voltage range than organic-based ferroelectric nonvolatile memory after removing the anti-ferroelectric behavior incorporating an electrolyte solution. The devices showed robust operation in bent states of bending radii up to 9 mm and in cycling tests of 200 times. The devices exhibited remarkable mechanical properties and were readily integrated with plastic substrates for the production of flexible circuits.

  10. Hierarchical nitrogen doped bismuth niobate architectures: Controllable synthesis and excellent photocatalytic activity

    International Nuclear Information System (INIS)

    Hou, Jungang; Cao, Rui; Wang, Zheng; Jiao, Shuqiang; Zhu, Hongmin

    2012-01-01

    Graphical abstract: Efficient visible-light-driven photocatalysts of peony-like nitrogen doped Bi 3 NbO 7 hierarchical architectures and silver-layered Bi 3 NbO 7−x Nx heterostructures were successfully synthesized in this discovery. Highlights: ► N-Bi 3 NbO 7 architectures were synthesized via two-step hydrothermal process. ► Electronic structure calculations indicated that N replaced O in samples. ► Growth mechanism is proposed for transformation of nanoparticles to microflowers. ► Excellent activities of N-Bi 3 NbO 7 architectures were obtained for degradation. ► Enhanced photocatalytic performance was observed for Ag/N-Bi 3 NbO 7 architectures. - Abstract: Nitrogen doped bismuth niobate (N-Bi 3 NbO 7 ) hierarchical architectures were synthesized via a facile two-step hydrothermal process. XRD patterns revealed that the defect fluorite-type crystal structure of Bi 3 NbO 7 remained intact upon nitrogen doping. Electron microscopy showed the N-Bi 3 NbO 7 architecture has a unique peony-like spherical superstructure composed of numerous nanosheets. UV–vis spectra indicated that nitrogen doping in the compound results in a red-shift of the absorption edge from 450 nm to 470 nm. XPS indicated that [Bi/Nb]-N bonds were formed by inducing nitrogen to replace a small amount of oxygen in Bi 3 NbO 7−x N x , which is explained by electronic structure calculations including energy band and density of states. Based on observations of architectures formation, a possible growth mechanism was proposed to explain the transformation of polyhedral-like nanoparticles to peony-like microflowers via an Ostwald riping mechanism followed by self-assembly. The N-Bi 3 NbO 7 architectures due to the large specific surface area and nitrogen doping exhibited higher photocatalytic activities in the decomposition of organic pollutant under visible-light irradiation than Bi 3 NbO 7 nanoparticles. Furthermore, an enhanced photocatalytic performance was also observed for Ag

  11. Computational study of textured ferroelectric polycrystals: Dielectric and piezoelectric properties of template-matrix composites

    Science.gov (United States)

    Zhou, Jie E.; Yan, Yongke; Priya, Shashank; Wang, Yu U.

    2017-01-01

    Quantitative relationships between processing, microstructure, and properties in textured ferroelectric polycrystals and the underlying responsible mechanisms are investigated by phase field modeling and computer simulation. This study focuses on three important aspects of textured ferroelectric ceramics: (i) grain microstructure evolution during templated grain growth processing, (ii) crystallographic texture development as a function of volume fraction and seed size of the templates, and (iii) dielectric and piezoelectric properties of the obtained template-matrix composites of textured polycrystals. Findings on the third aspect are presented here, while an accompanying paper of this work reports findings on the first two aspects. In this paper, the competing effects of crystallographic texture and template seed volume fraction on the dielectric and piezoelectric properties of ferroelectric polycrystals are investigated. The phase field model of ferroelectric composites consisting of template seeds embedded in matrix grains is developed to simulate domain evolution, polarization-electric field (P-E), and strain-electric field (ɛ-E) hysteresis loops. The coercive field, remnant polarization, dielectric permittivity, piezoelectric coefficient, and dissipation factor are studied as a function of grain texture and template seed volume fraction. It is found that, while crystallographic texture significantly improves the polycrystal properties towards those of single crystals, a higher volume fraction of template seeds tends to decrease the electromechanical properties, thus canceling the advantage of ferroelectric polycrystals textured by templated grain growth processing. This competing detrimental effect is shown to arise from the composite effect, where the template phase possesses material properties inferior to the matrix phase, causing mechanical clamping and charge accumulation at inter-phase interfaces between matrix and template inclusions. The computational

  12. Magnetic enhancement of ferroelectric polarization in a self-grown ferroelectric-ferromagnetic composite

    Science.gov (United States)

    Kumar, Amit; Narayan, Bastola; Pachat, Rohit; Ranjan, Rajeev

    2018-02-01

    Ferroelectric-ferromagnetic multiferroic composites are of great interest both from the scientific and technological standpoints. The extent of coupling between polarization and magnetization in such two-phase systems depends on how efficiently the magnetostrictive and electrostrictive/piezoelectric strain gets transferred from one phase to the other. This challenge is most profound in the easy to make 0-3 ferroelectric-ferromagnetic particulate composites. Here we report a self-grown ferroelectric-ferromagnetic 0-3 particulate composite through controlled spontaneous precipitation of ferrimagnetic barium hexaferrite phase (BaF e12O19 ) amid ferroelectric grains in the multiferroic alloy system BiFe O3-BaTi O3 . We demonstrate that a composite specimen exhibiting merely ˜1% hexaferrite phase exhibits ˜34% increase in saturation polarization in a dc magnetic field of ˜10 kOe. Using modified Rayleigh analysis of the polarization field loop in the subcoercive field region we argue that the substantial enhancement in the ferroelectric switching is associated with the reduction in the barrier heights of the pinning centers of the ferroelectric-ferroelastic domain walls in the stress field generated by magnetostriction in the hexaferrite grains when the magnetic field is turned on. Our study proves that controlled precipitation of the magnetic phase is a good strategy for synthesis of 0-3 ferroelectric-ferromagnetic particulate multiferroic composite as it not only helps in ensuring a good electrical insulating character of the composite, enabling it to sustain high enough electric field for ferroelectric switching, but also the factors associated with the spontaneity of the precipitation process ensure efficient transfer of the magnetostrictive strain/stress to the surrounding ferroelectric matrix making domain wall motion easy.

  13. Uncooled monolithic ferroelectric IRFPA technology

    Science.gov (United States)

    Belcher, James F.; Hanson, Charles M.; Beratan, Howard R.; Udayakumar, K. R.; Soch, Kevin L.

    1998-10-01

    Once relegated to expensive military platforms, occasionally to civilian platforms, and envisioned for individual soldiers, uncooled thermal imaging affords cost-effective solutions for police cars, commercial surveillance, driving aids, and a variety of other industrial and consumer applications. System prices are continuing to drop, and swelling production volume will soon drive prices substantially lower. The impetus for further development is to improve performance. Hybrid barium strontium titanate (BST) detectors currently in production are relatively inexpensive, but have limited potential for improved performance. The MTF at high frequencies is limited by thermal conduction through the optical coating. Microbolometer arrays in development at Raytheon have recently demonstrated performance superior to hybrid detectors. However, microbolometer technology lacks a mature, low-cost system technology and an abundance of upgradable, deployable system implementations. Thin-film ferroelectric (TFFE) detectors have all the performance potential of microbolometers. They are also compatible with numerous fielded and planned system implementations. Like the resistive microbolometer, the TFFE detector is monolithic; i.e., the detector material is deposited directly on the readout IC rather than being bump bonded to it. Imaging arrays of 240 X 320 pixels have been produced, demonstrating the feasibility of the technology.

  14. Quantum switching of polarization in mesoscopic ferroelectrics

    International Nuclear Information System (INIS)

    Sa de Melo, C.A.

    1996-01-01

    A single domain of a uniaxial ferroelectric grain may be thought of as a classical permanent memory. At the mesoscopic level this system may experience considerable quantum fluctuations due to tunneling between two possible memory states, thus destroying the classical permanent memory effect. To study these quantum effects the concrete example of a mesoscopic uniaxial ferroelectric grain is discussed, where the orientation of the electric polarization determines two possible memory states. The possibility of quantum switching of the polarization in mesoscopic uniaxial ferroelectric grains is thus proposed. To determine the degree of memory loss, the tunneling rate between the two polarization states is calculated at zero temperature both in the absence and in the presence of an external static electric field. In addition, a discussion of crossover temperature between thermally activated behavior and quantum tunneling behavior is presented. And finally, environmental effects (phonons, defects, and surfaces) are also considered. copyright 1996 The American Physical Society

  15. Electrostatic micromotor based on ferroelectric ceramics

    Science.gov (United States)

    Baginsky, I. L.; Kostsov, E. G.

    2004-11-01

    A new electrostatic micromotor is described that utilizes the electromechanical energy conversion principle earlier described by the authors. The electromechanical energy conversion is based on reversible electrostatic rolling of thin metallic films (petals) on a ferroelectric surface. The motor's active media are layers of ferroelectric ceramics (about 100 µm in thickness). The characteristics of the electrostatic rolling of the petals on different ceramic surfaces are studied, as well as the dynamic characteristics of the micromotors. It is shown that the use of antiferroelectric material allows one to reach a specific energy capacitance comparable to that of the micromotors based on ferroelectric films and to achieve a specific power of 30-300 µW mm-2.

  16. Flexoelectricity: strain gradient effects in ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Ma Wenhui [Department of Physics, Shantou Unversity, Shantou, Guangdong 515063 (China)

    2007-12-15

    Mechanical strain gradient induced polarization effect or flexoelectricity in perovskite-type ferroelectric and relaxor ferroelectric ceramics was investigated. The flexoelectric coefficients measured at room temperature ranged from about 1 {mu} C m{sup -1} for lead zirconate titanate to 100 {mu} C m{sup -1} for barium strontium titanate. Flexoelectric effects were discovered to be sensitive to chemical makeup, phase symmetry, and domain structures. Based on phenomenological discussion and experimental data on flexoelectricity, the present study proposed that mechanical strain gradient field could influence polarization responses in a way analogous to electric field. Flexoelectric coefficients were found to be nonlinearly enhanced by dielectric permittivity and strain gradient. Interfacial mismatch in epitaxial thin films can give rise to high strain gradients, enabling flexoelectric effects to make a significant impact in properly engineered ferroelectric heterostructure systems.

  17. Ferroelectric domain continuity over grain boundaries

    DEFF Research Database (Denmark)

    Mantri, Sukriti; Oddershede, Jette; Damjanovic, Dragan

    2017-01-01

    Formation and mobility of domain walls in ferroelectric materials is responsible for many of their electrical and mechanical properties. Domain wall continuity across grain boundaries has been observed since the 1950's and is speculated to affect the grain boundary-domain interactions, thereby...... impacting macroscopic ferroelectric properties in polycrystalline systems. However detailed studies of such correlated domain structures across grain boundaries are limited. In this work, we have developed the mathematical requirements for domain wall plane matching at grain boundaries of any given...... orientation. We have also incorporated the effect of grain boundary ferroelectric polarization charge created when any two domains meet at the grain boundary plane. The probability of domain wall continuity for three specific grain misorientations is studied. Use of this knowledge to optimize processing...

  18. Light-induced space-charge fields for the structuration of dielectric materials; Lichtinduzierte Raumladungsfelder zur Strukturierung dielektrischer Materialien

    Energy Technology Data Exchange (ETDEWEB)

    Eggert, H A

    2006-11-15

    Light-induced space-charge fields in lithium-niobate crystals are used for patterning of dielectric materials. This includes tailored ferroelectric domains in the bulk of the crystal, different sorts of micro and nanoparticles on a crystal surface, as well as poling of electrooptic chromophores. A stochastical model is introduced, which can describe the spatial inhomogeneous domain inversion. (orig.)

  19. Light-induced space-charge fields for the structuration of dielectric materials

    International Nuclear Information System (INIS)

    Eggert, H.A.

    2006-11-01

    Light-induced space-charge fields in lithium-niobate crystals are used for patterning of dielectric materials. This includes tailored ferroelectric domains in the bulk of the crystal, different sorts of micro and nanoparticles on a crystal surface, as well as poling of electrooptic chromophores. A stochastical model is introduced, which can describe the spatial inhomogeneous domain inversion. (orig.)

  20. Internal bias field in glycine phosphite crystal

    International Nuclear Information System (INIS)

    Nayeem, Jannatul; Wakabayashi, Hiroshi; Kikuta, Toshio; Yamazaki, Toshinari; Nakatani, Noriyuki

    2003-01-01

    The distributions of internal bias field E b have been investigated under the carbon-powder pattern and mercury electrode techniques in GPI ferroelectric crystals. Polarity and intensity of E b are distributed depending on crystal growth sectors. Crystal symmetry 2/m is observed obviously in the distribution of E b . The polarities of E b are head-to-head manner in those growth sectors where a surface is growing parallel to the crystallographic a-axis and tail-to-tail manner in the other growth sectors in the crystal. The maximum intensity of E b is found in the sectors (010) where the growing surfaces are perpendicular to the ferroelectric b-axis

  1. Ferroelectric Cathodes in Transverse Magnetic Fields

    International Nuclear Information System (INIS)

    Alexander Dunaevsky; Yevgeny Raitses; Nathaniel J. Fisch

    2002-01-01

    Experimental investigations of a planar ferroelectric cathode in a transverse magnetic field up to 3 kGs are presented. It is shown that the transverse magnetic field affects differently the operation of ferroelectric plasma cathodes in ''bright'' and ''dark'' modes in vacuum. In the ''bright'' mode, when the surface plasma is formed, the application of the transverse magnetic field leads to an increase of the surface plasma density. In the ''dark'' mode, the magnetic field inhibits the development of electron avalanches along the surface, as it does similarly in other kinds of surface discharges in the pre-breakdown mode

  2. Composition driven structural instability in perovskite ferroelectrics

    Directory of Open Access Journals (Sweden)

    Chao Xu

    2017-04-01

    Full Text Available Ferroelectric solid solutions usually exhibit enhanced functional properties at the morphotropic phase boundary separating two ferroelectric phases with different orientations of polarization. The underlying mechanism is generally associated with polarization rotational instability and the flattened free energy profile. In this work we show that the polarization extensional instability can also be induced at the morphotropic phase boundary beyond the reported polar-nonpolar phase boundary. The piezoelectricity enhanced by this mechanism exhibits excellent thermal stability, which helps to develop high performance piezoelectric materials with good temperature stability.

  3. Switching Characteristics of Ferroelectric Transistor Inverters

    Science.gov (United States)

    Laws, Crystal; Mitchell, Coey; MacLeod, Todd C.; Ho, Fat D.

    2010-01-01

    This paper presents the switching characteristics of an inverter circuit using a ferroelectric field effect transistor, FeFET. The propagation delay time characteristics, phl and plh are presented along with the output voltage rise and fall times, rise and fall. The propagation delay is the time-delay between the V50% transitions of the input and output voltages. The rise and fall times are the times required for the output voltages to transition between the voltage levels V10% and V90%. Comparisons are made between the MOSFET inverter and the ferroelectric transistor inverter.

  4. Dielectric and magnetic properties, and electronic structure of multiferroic perovskite PbFe.sub.0.5./sub.Ta.sub.0.5./sub.O.sub.3./sub. and incipient ferroelectric pyrochlore Pb.sub.2./sub.Fe.sub.0.34./sub.Ta.sub.1.84./sub.O.sub.7.11./sub. single crystals and ceramics

    Czech Academy of Sciences Publication Activity Database

    Kania, A.; Miga, S.; Talik, E.; Gruszka, I.; Szubka, M.; Savinov, Maxim; Prokleška, J.; Kamba, Stanislav

    2016-01-01

    Roč. 36, č. 14 (2016), s. 3369-3381 ISSN 0955-2219 R&D Projects: GA ČR GA15-08389S Institutional support: RVO:68378271 Keywords : lead iron tantalate * perovskite multiferroic * pyrochlore * incipient ferroelectric * X-ray photoelectron spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.411, year: 2016

  5. Cascaded quadratic soliton compression of high-power femtosecond fiber lasers in Lithium Niobate crystals

    DEFF Research Database (Denmark)

    Bache, Morten; Moses, Jeffrey; Wise, Frank W.

    2008-01-01

    The output of a high-power femtosecond fiber laser is typically 300 fs with a wavelength around $\\lambda=1030-1060$ nm. Our numerical simulations show that cascaded quadratic soliton compression in bulk LiNbO$_3$ can compress such pulses to below 100 fs.......The output of a high-power femtosecond fiber laser is typically 300 fs with a wavelength around $\\lambda=1030-1060$ nm. Our numerical simulations show that cascaded quadratic soliton compression in bulk LiNbO$_3$ can compress such pulses to below 100 fs....

  6. Laser induced Erasable Patterns in a N* Liquid Crystal on an Iron Doped Lithium Niobate (Postprint)

    Science.gov (United States)

    2017-10-12

    4685; Clearance Date: 22 Sep 2017. This document contains color . Journal article published in Optics Express, Vol. 25, No. 21, 22 Sep 2017. © 2017...be applied selectively to erase these patterns. Thus, a promising method is reported to generate reconfigurable patterns, photonic motives , and...erase these patterns. Thus, a promising method is reported to generate reconfigurable patterns, photonic motives , and touch sensitive devices in a

  7. Refractive-index changes in lithium niobate crystals by radiation damages

    International Nuclear Information System (INIS)

    Zamani Meymian, Mohammad Reza

    2007-01-01

    For the study in this thesis 3 He 2+ ions with the energy of about 40 MeV were applied. The results of these studies show a timely very stable anisotrope refractive-index change in the range of some 10 -3 . The radiation damages caused by ions cause a decreasement of the ordinary refractive index n o and an increasement of the extra-ordinary refractive index n e . While the absolute values for Δn o and Δn e are nearly equal the birefringence of the material (n e -n o ) smaller. The generated refractive-index change is dose dependent and the curve Δn has at increasing dose a strongly nonlinear slope with a characteristic stage at the radiation dose of about 2 x 10 20 ions/m 2

  8. Annealed proton exchanged optical waveguides in lithium niobate differences between the X- and Z-cuts

    CERN Document Server

    Nekvindova, P; Cervena, J; Budnar, M; Razpet, A; Zorko, B; Pelicon, P; 10.1016/S0925-3467(01)00186-0

    2002-01-01

    Summarizes results and assessments of our systematic fabrication and characterization of proton exchanged (PE) and annealed proton exchanged (APE) waveguides in lithium niobate. This study focused on different behavior of crystallographically diverse X(1120) and Z (0001) substrate cuts during waveguide fabrication, and differences in characteristics of the resulting waveguides. Non-toxic adipic acid was used as a proton source, and the waveguides properties were defined by mode spectroscopy (waveguide characteristics) and neutron depth profiling (NDP, lithium concentration and distribution), infrared vibration spectra and elastic recoil detection analysis (ERDA, concentration and depth distribution of hydrogen). It was discovered that the X-cut structure is more permeable for moving particles (lithium and hydrogen ions), which leads to a higher effectiveness of the PE process within the X-cut. The explanation of this phenomenon is based on fitting X-cut orientation towards cleavage planes of lithium niobate c...

  9. Design of multi-wavelength tunable filter based on Lithium Niobate

    Science.gov (United States)

    Zhang, Ailing; Yao, Yuan; Zhang, Yue; Song, Hongyun

    2018-05-01

    A multi-wavelength tunable filter is designed. It consists of multiple waveguides among multiple waveguide gratings. A pair of electrodes were placed on both sides of each waveguide. The tunable filter uses the electro-optic effect of Lithium Niobate to tune the phase caused by each waveguide. Consequently, the wavelength and wavelength spacing of the filter are tuned by changing external voltages added on the electrode pairs. The tunable property of the filter is analyzed by phase matching condition and transfer-matrix method. Numerical results show that not only multiple wavelengths with narrow bandwidth are tuned with nearly equal spacing by synchronously changing the voltages added on all electrode pairs, but also the number of wavelengths is determined by the number of phase shifts caused by electrode pairs. Furthermore, due to the electro-optic effect of Lithium Niobate, the tuning speed of the filter can reach the order of ns.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    Spherical silver nanoparticles were prepared by means of ion beam synthesis in lithium niobate. The embedded nanoparticles were then irradiated with energetic "8"4Kr and "1"9"7Au 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. (paper)

  11. Properties of complex tungstates, niobates, translated with fluorite-like structure

    International Nuclear Information System (INIS)

    Vetkina, S.N.; Zolin, V.F.; Sirotinkin, V.P.; Smirnov, S.A.

    1989-01-01

    Spectra of ternary tungstates, niobates and tantalates (MeLa 2 WO 7 , La 3 TO 7 ; Me=Ba, Sr; T=Ta, Nb) related to the layered fluorite group are analyzed. The laser pumping and time resolved luminescence are used for selecting spectra of unequivalent centers. The symmetry of the first center is near to the distorted cubic one. The vibrational spectra of europium in Eu 3 NbO 7 and SrLa 2 WO 7 are due to the chain-like structure of niobates and to the net-like structure of tantalates. The stimulated emission of Nd 3+ in powders of BaLa 2 WO 7 and La 3 NbO 7 is observed at wavelengths of 1.07 and 1.063 μm, respectively

  12. Organic ferroelectric opto-electronic memories

    NARCIS (Netherlands)

    Asadi, K.; Li, M.; Blom, P.W.M.; Kemerink, M.; Leeuw, D.M. de

    2011-01-01

    Memory is a prerequisite for many electronic devices. Organic non-volatile memory devices based on ferroelectricity are a promising approach towards the development of a low-cost memory technology based on a simple cross-bar array. In this review article we discuss the latest developments in this

  13. Distribution of correlation radii in disordered ferroelectrics

    Czech Academy of Sciences Publication Activity Database

    Glinchuk, M. D.; Eliseev, E. A.; Stepanovich, V. A.; Jastrabík, Lubomír

    2002-01-01

    Roč. 81, č. 25 (2002), s. 4808-4810 ISSN 0003-6951 R&D Projects: GA MŠk LN00A015 Institutional research plan: CEZ:AV0Z1010914 Keywords : disordered ferroelectrics * distribution of correlation radii * polar nanoregions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.207, year: 2002

  14. Organic Nonvolatile Memory Devices Based on Ferroelectricity

    NARCIS (Netherlands)

    Naber, Ronald C. G.; Asadi, Kamal; Blom, Paul W. M.; de Leeuw, Dago M.; de Boer, Bert

    2010-01-01

    A memory functionality is a prerequisite for many applications of electronic devices. Organic nonvolatile memory devices based on ferroelectricity are a promising approach toward the development of a low-cost memory technology. In this Review Article we discuss the latest developments in this area

  15. Organic nonvolatile memory devices based on ferroelectricity

    NARCIS (Netherlands)

    Naber, R.C.G.; Asadi, K.; Blom, P.W.M.; Leeuw, D.M. de; Boer, B. de

    2010-01-01

    A memory functionality is a prerequisite for many applications of electronic devices. Organic nonvolatile memory devices based on ferroelectricity are a promising approach toward the development of a low-cost memory technology. In this Review Article we discuss the latest developments in this area

  16. Giant electrocaloric effect in a cracked ferroelectrics

    Science.gov (United States)

    Huang, Cheng; Yang, Hai-Bing; Gao, Cun-Fa

    2018-04-01

    The electrocaloric effect (ECE) is the temperature change in a material induced by electrical field variation under adiabatic condition. Considering an external electric load applied on a cracked ferroelectric solid, a non-uniform electric field would be induced at the crack tip, and thus, incompatible strain field and local stress concentration would be generated around it. Furthermore, the enormous strain energy and the electrostatic energy would affect the polarization switching of the ferroelectric solid, important for the electrocaloric response. In this paper, the large negative and positive ECEs in a ferroelectric sheet with a conducting crack are investigated by the phase field method with the consideration of time-dependent Ginzburg-Landau equation. The numerical calculations indicated that the polarization field generates a sharp rise during the domain transition from polydomain to monodomain under a certain electric load. Large negative ECEs, about -10.21 K and -7.55 K, are obtained at 135 °C and 85 °C, respectively. The domain transition temperature is much lower than the Curie temperature, which enlarges the existence scope of the large ECE in ferroelectrics. The results also imply that the domain transition from a multi-domain state to a single domain takes place with the minimization of total free energy, which involves the courses of the electric field, stress field, temperature, and polarization interaction. Therefore, the non-uniform distributions of the stress-electric fields induced by the crack play an important role in ECE.

  17. From antiferroelectricity to ferroelectricity in smectic mesophases ...

    Indian Academy of Sciences (India)

    are not ferroelectric in the ground state, but upon alignment within an electric field .... Figure 3. Molecular organisation within polar smectic phases and possible ways to escape from a macroscopic polarisation in mesophases built up by polar layers. .... in which the molecules adapt a twisted orientation from the top to bottom.

  18. Data retention in organic ferroelectric resistive switches

    NARCIS (Netherlands)

    Khikhlovskyi, V.; Breemen, A.J.J.M. van; Janssen, R.A.J.; Gelinck, G.H.; Kemerink, M.

    2016-01-01

    Solution-processed organic ferroelectric resistive switches could become the long-missing non-volatile memory elements in organic electronic devices. To this end, data retention in these devices should be characterized, understood and controlled. First, it is shown that the measurement protocol can

  19. Electrical characterization of thin film ferroelectric capacitors

    NARCIS (Netherlands)

    Tiggelman, M.P.J.; Reimann, K.; Klee, M.; Beelen, D.; Keur, W.; Schmitz, Jurriaan; Hueting, Raymond Josephus Engelbart

    2006-01-01

    Tunable capacitors can be used to facilitate the reduction of components in wireless technologies. The tunability of the capacitors is caused by the sensitivity of the relative dielectric constant to a change in polarization with electric field. Thin film ferroelectric MIM capacitors on silicon

  20. Photovoltaic effect in ferroelectric ceramics

    Science.gov (United States)

    Epstein, D. J.; Linz, A.; Jenssen, H. P.

    1982-01-01

    The ceramic structure was simulated in a form that is more tractable to correlation between experiment and theory. Single crystals (of barium titanate) were fabricated in a simple corrugated structure in which the pedestals of the corrugation simulated the grain while the intervening cuts could be filled with materials simulating the grain boundaries. The observed photovoltages were extremely small (100 mv).

  1. Temperature dependence of the thermoelectric coeffiicients of lithium niobate and lithium tantalate

    International Nuclear Information System (INIS)

    Khachaturyan, O.A.; Gabrielyan, A.I.; Kolesnik, S.P.

    1988-01-01

    Thermoelectric Zeebeck,Thomson, Peltier coefficients for LiNbO 3 and LiTaO 3 monocrystals and their dependence on temperature in 300-1400 K range were investigated. It is shown that Zeebeck (α) coefficient changes its sign, depending on temperature change - the higher is α, the higher is material conductivity in the corresponding temperature region. Thomson and Peltier coefficients were calculated analytically for lithium niobate and tantalate

  2. Generation of tunable narrow-band surface-emitted terahertz radiation in periodically poled lithium niobate.

    Science.gov (United States)

    Weiss, C; Torosyan, G; Avetisyan, Y; Beigang, R

    2001-04-15

    Generation of tunable narrow-band terahertz (THz) radiation perpendicular to the surface of periodically poled lithium niobate by optical rectification of femtosecond pulses is reported. The generated THz radiation can be tuned by use of different poling periods and different observation angles, limited only by the available bandwidth of the pump pulse. Typical bandwidths were 50-100 GHz, depending on the collection angle and the number of periods involved.

  3. Generating Efficient Femtosecond Mid-infrared Pulse by Single Near-infrared Pump Wavelength in Bulk Nonlinear Crystal Without Phase-matching

    DEFF Research Database (Denmark)

    Zhou, Binbin; Guo, Hairun; Bache, Morten

    2014-01-01

    We experimentally demonstrate efficient mid-infrared pulse generation by dispersive wave radiation in bulk lithium niobate crystal. Femtosecond mid-IR pulses centering from 2.8-2.92 μm are generated using the single pump wavelengths from 1.25-1.45 μm. © 2014 Optical Society of America...

  4. Aggregate linear properties of ferroelectric ceramics and polycrystalline thin films: Calculation by the method of effective piezoelectric medium

    Science.gov (United States)

    Pertsev, N. A.; Zembilgotov, A. G.; Waser, R.

    1998-08-01

    The effective dielectric, piezoelectric, and elastic constants of polycrystalline ferroelectric materials are calculated from single-crystal data by an advanced method of effective medium, which takes into account the piezoelectric interactions between grains in full measure. For bulk BaTiO3 and PbTiO3 polarized ceramics, the dependences of material constants on the remanent polarization are reported. Dielectric and elastic constants are computed also for unpolarized c- and a-textured ferroelectric thin films deposited on cubic or amorphous substrates. It is found that the dielectric properties of BaTiO3 and PbTiO3 polycrystalline thin films strongly depend on the type of crystal texture. The influence of two-dimensional clamping by the substrate on the dielectric and piezoelectric responses of polarized films is described quantitatively and shown to be especially important for the piezoelectric charge coefficient of BaTiO3 films.

  5. Optimal configuration of microstructure in ferroelectric materials by stochastic optimization

    Science.gov (United States)

    Jayachandran, K. P.; Guedes, J. M.; Rodrigues, H. C.

    2010-07-01

    An optimization procedure determining the ideal configuration at the microstructural level of ferroelectric (FE) materials is applied to maximize piezoelectricity. Piezoelectricity in ceramic FEs differs significantly from that of single crystals because of the presence of crystallites (grains) possessing crystallographic axes aligned imperfectly. The piezoelectric properties of a polycrystalline (ceramic) FE is inextricably related to the grain orientation distribution (texture). The set of combination of variables, known as solution space, which dictates the texture of a ceramic is unlimited and hence the choice of the optimal solution which maximizes the piezoelectricity is complicated. Thus, a stochastic global optimization combined with homogenization is employed for the identification of the optimal granular configuration of the FE ceramic microstructure with optimum piezoelectric properties. The macroscopic equilibrium piezoelectric properties of polycrystalline FE is calculated using mathematical homogenization at each iteration step. The configuration of grains characterized by its orientations at each iteration is generated using a randomly selected set of orientation distribution parameters. The optimization procedure applied to the single crystalline phase compares well with the experimental data. Apparent enhancement of piezoelectric coefficient d33 is observed in an optimally oriented BaTiO3 single crystal. Based on the good agreement of results with the published data in single crystals, we proceed to apply the methodology in polycrystals. A configuration of crystallites, simultaneously constraining the orientation distribution of the c-axis (polar axis) while incorporating ab-plane randomness, which would multiply the overall piezoelectricity in ceramic BaTiO3 is also identified. The orientation distribution of the c-axes is found to be a narrow Gaussian distribution centered around 45°. The piezoelectric coefficient in such a ceramic is found to

  6. Stable Ferroelectric Behavior of Nb-Modified Bi0.5K0.5TiO3-Bi(Mg0.5Ti0.5)O3 Lead-Free Relaxor Ferroelectric Ceramics

    Science.gov (United States)

    Zaman, Arif; Malik, Rizwan Ahmed; Maqbool, Adnan; Hussain, Ali; Ahmed, Tanveer; Song, Tae Kwon; Kim, Won-Jeong; Kim, Myong-Ho

    2018-03-01

    Crystal structure, dielectric, ferroelectric, piezoelectric, and electric field-induced strain properties of lead-free Nb-modified 0.96Bi0.5K0.5TiO3-0.04Bi(Mg0.5Ti0.5)O3 (BKT-BMT) piezoelectric ceramics were investigated. Crystal structure analysis showed a gradual phase transition from tetragonal to pseudocubic phase with increasing Nb content. The optimal piezoelectric property of small-signal d 33 was enhanced up to ˜ 68 pC/N with a lower coercive field ( E c) of ˜ 22 kV/cm and an improved remnant polarization ( P r) of ˜ 13 μC/cm2 for x = 0.020. A relaxor-like behavior with a frequency-dependent Curie temperature T m was observed, and a high T m around 320°C was obtained in the investigated system. This study suggests that the ferroelectric properties of BKT-BMT was significantly improved by means of Nb substitution. The possible shift of depolarization temperature T d toward high temperature T m may have triggered the spontaneous relaxor to ferroelectric phase transition with long-range ferroelectric order without any traces of a nonergodic relaxor state in contradiction with Bi0.5Na0.5TiO3-based systems. The possible enhancement in ferroelectric and piezoelectric properties near the critical composition x = 0.020 may be attributed to the increased anharmonicity of lattice vibrations which may facilitate the observed phase transition from a low-symmetry tetragonal to a high-symmetry cubic phase with a decrease in the lattice anisotropy of an undoped sample. This highly flexible (at a unit cell level) narrow compositional range triggers the enhancement of d 33 and P r values.

  7. An EPMA study on KNbO3 and NaNbO3 single crystals - potential reference materials for quantitative microanalysis

    International Nuclear Information System (INIS)

    Samardzzija, Z.; Bernik, S.; Malic, B.; Ceh, M.; Marinenko, R.B.

    2004-01-01

    Single crystals of KNbO 3 and NaNbO 3 were selected from the limited number of suitable alkali compounds that are available and evaluated as possible reference materials for the electron-probe microanalysis (EPMA) of alkaline niobates with a composition described by the general formula K 1-x Na x NbO 3 . The EPMA study verified that KNbO 3 and NaNbO 3 single crystals are stable under the electron beam and compositionally homogeneous. A quantitative microanalysis confirmed the composition of pure KNbO 3 , while the NaNbO 3 crystal contained 0.3 mass fraction % of Ca. A significant improvement in the accuracy of the quantitative EPMA of polycrystalline potassium-sodium niobates was achieved using these single crystals as standards. The crystals can also be useful as reference materials for the analysis of sodium and potassium in other materials. (author)

  8. Modelling Ferroelectric Nanoparticles in Nematic Liquid Crystals (FERNANO)

    Science.gov (United States)

    2015-02-26

    DIPARTIMENTO DI CHIMICA FISICA ED INORGANICA VIALE DEL RISORGIMENTO 4 BOLOGNA, 40136 ITALY EOARD GRANT #FA8655-11-1-3046 Report...AND ADDRESS(ES) DIPARTIMENTO DI CHIMICA FISICA ED INORGANICA VIALE DEL RISORGIMENTO 4 BOLOGNA, 40136 ITALY 8. PERFORMING ORGANIZATION

  9. Giant Electrocaloric Effect in Ferroelectrics with Tailored Polaw-Nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qiming [Pennsylvania State Univ., University Park, PA (United States)

    2015-06-24

    systems with nano- and meso-scale disorders. Through the efforts of this DoE program, we have developed understandings for many questions and materials approaches for many hypotheses listed above. The major accomplishments include: (i) The first one to show that a giant ECE can be obtained in bulk materials of ferroelectric P(VDF-TrFE) copolymer, which has a large ß coefficient and high polarization, near FE-PE transition.[1,3,12] (ii) The first who developed the theoretical analyses on the upper bound of dipolar entropy change in polar-materials and the general approach to maximize the coexisting phases with vanishingly small switching fields among the coexisting phases[10,23] Experimental results confirm these theoretical predictions.[24] (iii) The first to show that the relaxor ferroelectrics, due to built-in defects structures at nano- and meso scale, exhibit a giant ECE over a broad temperature range.[1,3,7,14] (iv) The first to show that a large ECE can be obtained near order-disorder transition in dielectric fluids such as liquid crystals with large dielectric anisotropy. Also the study developed a general approach for developing dielectric fluids to achieve a large electric field induced entropy change.[26] (v) We are starting to explore the multi-field effect (multiferroic effect) in nanocomposites in which there exist large dielectric contrasts between the matrix and nanofilelrs and showed that a significantly enhanced ECE compared with polymer matrix.[36] (vi) By facially tuning the nano- and meso-scale dipolar coupling, we are the first to show that an anomalous ECE can be obtained in a relaxor/normal ferroelectric blend.[39] (vii) Introduced and demonstrated that the internal bias field approach can be effective in enhancing the EC response at low electric field. The result is significant since for practical applications, a low applied field is highly desired. (viii) A high sensitivity ECE characterization system has been developed. This program has made

  10. The relative contribution of ferroelastic and ferroelectric texture to the character of a hard PZT ceramic

    Science.gov (United States)

    Key, Thomas Stallings

    The development of ferroelastic (90°) texture in addition to ferroelectric (180°) texture is essential to maximizing the piezoelectric properties of many hard tetragonal PZTs, including Piezoetechnologies K270. Ferroelastic texture results from motion of domain walls that is dependent on an individual crystals orientation. Increases in ferroelastic texture raises the maximum net polarization that can be achieved by changes in ferroelectric texture. By studying a hard PZT poled under various temperature conditions, insight was gained into factors affecting the development of ferroelastic texture and how ferroelastic texture contributes to piezoelectric properties. Depinning proved to be the major barrier to preventing ferroelastic domain wall motion where strain based domain interactions and polar defect complexes on the domain level appear to be the dominant factors. Insight into the affect of increased domain texture on the relationship between the increasing magnitude of the remnant polarization (|Pr|) and the magnitude of the coercive field (|EC|) was gained by plotting |EC| vs. |Pr| as a function of poling time for a variety of poling temperatures. At low |Pr| values, |EC| increased rapidly as a function of increases in |Pr| regardless of the poling temperature. This relationship was characteristic of samples poled at 25 °C where increases in ferroelastic texture were largely suppressed. Because increases in polarization were still observable changes in ferroelectric texture most responsible for the polarization increase and like play a strong role in the initial |EC| vs. |Pr| relationship. As |Pr| increased beyond 5 to 8 iC/cm2, the slope of |EC| vs. |Pr| decreased where the reduction in slope increased with poling temperature. This only occurred in samples poled at elevated temperatures where ferroelastic texture was know to ultimately develop during the poling process, leading to the suggestion that the change in slope was due to increases in combined

  11. Out-of-Plane Piezoelectricity and Ferroelectricity in Layered α-In2Se3 Nanoflakes.

    Science.gov (United States)

    Zhou, Yu; Wu, Di; Zhu, Yihan; Cho, Yujin; He, Qing; Yang, Xiao; Herrera, Kevin; Chu, Zhaodong; Han, Yu; Downer, Michael C; Peng, Hailin; Lai, Keji

    2017-09-13

    Piezoelectric and ferroelectric properties in the two-dimensional (2D) limit are highly desired for nanoelectronic, electromechanical, and optoelectronic applications. Here we report the first experimental evidence of out-of-plane piezoelectricity and ferroelectricity in van der Waals layered α-In 2 Se 3 nanoflakes. The noncentrosymmetric R3m symmetry of the α-In 2 Se 3 samples is confirmed by scanning transmission electron microscopy, second-harmonic generation, and Raman spectroscopy measurements. Domains with opposite polarizations are visualized by piezo-response force microscopy. Single-point poling experiments suggest that the polarization is potentially switchable for α-In 2 Se 3 nanoflakes with thicknesses down to ∼10 nm. The piezotronic effect is demonstrated in two-terminal devices, where the Schottky barrier can be modulated by the strain-induced piezopotential. Our work on polar α-In 2 Se 3 , one of the model 2D piezoelectrics and ferroelectrics with simple crystal structures, shows its great potential in electronic and photonic applications.

  12. Local switching of two-dimensional superconductivity using the ferroelectric field effect

    Science.gov (United States)

    Takahashi, K. S.; Gabay, M.; Jaccard, D.; Shibuya, K.; Ohnishi, T.; Lippmaa, M.; Triscone, J.-M.

    2006-05-01

    Correlated oxides display a variety of extraordinary physical properties including high-temperature superconductivity and colossal magnetoresistance. In these materials, strong electronic correlations often lead to competing ground states that are sensitive to many parameters-in particular the doping level-so that complex phase diagrams are observed. A flexible way to explore the role of doping is to tune the electron or hole concentration with electric fields, as is done in standard semiconductor field effect transistors. Here we demonstrate a model oxide system based on high-quality heterostructures in which the ferroelectric field effect approach can be studied. We use a single-crystal film of the perovskite superconductor Nb-doped SrTiO3 as the superconducting channel and ferroelectric Pb(Zr,Ti)O3 as the gate oxide. Atomic force microscopy is used to locally reverse the ferroelectric polarization, thus inducing large resistivity and carrier modulations, resulting in a clear shift in the superconducting critical temperature. Field-induced switching from the normal state to the (zero resistance) superconducting state was achieved at a well-defined temperature. This unique system could lead to a field of research in which devices are realized by locally defining in the same material superconducting and normal regions with `perfect' interfaces, the interface being purely electronic. Using this approach, one could potentially design one-dimensional superconducting wires, superconducting rings and junctions, superconducting quantum interference devices (SQUIDs) or arrays of pinning centres.

  13. Synthesis and ferroelectric properties of rare earth compounds with tungsten bronze-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Bouziane, M., E-mail: bouzianemeryem@yahoo.fr [Laboratoire de Chimie du Solide Appliquee, Faculte des Sciences, Avenue Ibn Batouta, BP 1014, Rabat (Morocco); Taibi, M. [Laboratoire de Physico-Chimie des Materiaux, LAF 502, Ecole Normale Superieure, BP 5118, Rabat (Morocco); Boukhari, A. [Laboratoire de Chimie du Solide Appliquee, Faculte des Sciences, Avenue Ibn Batouta, BP 1014, Rabat (Morocco)

    2011-10-03

    Highlights: {center_dot} Polycrystalline materials with the tungsten bronze-type structure have been synthesized and characterized. {center_dot} Effect of the incorporation of rare earth ions and paramagnetic cations (Fe{sup 3+}) into a matrix ferroelectrically active was studied. {center_dot} Ferroelectric transition is pronounced by a large thermal hysteresis during the heating and cooling cycles. {center_dot} Phase transitions around T{sub c} were confirmed by differential scanning calorimetry (DSC) measurements. - Abstract: Polycrystalline materials with a general formula Pb{sub 2}Na{sub 0.8}R{sub 0.2}Nb{sub 4.8}Fe{sub 0.2}O{sub 15} (R = Dy, Eu, Sm, Nd, La) have been synthesized, in air by a high temperature solid state reaction method. X-ray diffraction study, at room temperature, revealed that they crystallize in the tungsten bronze-type structure. Dielectric properties were performed, in the temperature range 25-500 deg. C, at three different frequencies 10, 100 and 1000 kHz. The ferroelectric transition is pronounced by a large thermal hysteresis during the heating and cooling cycles. The determined Curie temperature values T{sub c} were discussed as a function of rare earth size. Phase transitions around T{sub c} for the investigated compounds were confirmed by differential scanning calorimetry (DSC) measurements.

  14. Gamma Radiation Damage Evaluation Studies on Ferroelectric La and Nb doped PZT Related Ceramics

    International Nuclear Information System (INIS)

    Cruz, Carlos M.; Pinnera, Ibrahin; Rodriguez, Arturo; Durruti, Ma. Dolores; Hernandez, Moises; Yannez-Limon, J. M.

    2015-01-01

    It is reported the research results of the gamma radiation damage evaluation on La (crystalline sites A) and / or Nb (crystalline sites B) doped ferroelectric PZT ceramics, which were irradiated with 60 Co gamma rays by applying two irradiation regimes: up to 125 lGy (irradiation steps of 25 kGy) and up to 700 kGy (irradiation steps of 100 kGy) exposition doses. The X Ray Diffraction pattern profiles of the irradiated sample were analyzed and the induced crystalline structure changes are reported and correlated with the observed irradiation induced changes on their ferroelectric properties on regard of the irradiation doses. Through the application of the MCCM atom displacements calculations algorithm and code, total dpa profiles were calculated for the studied samples, as well as, the dpa contributions of the different atomics species, where the atom displacements threshold energies were extrapolated from the values calculated by Molecular Dynamic methods for BaTiO 3 system. An evaluation of the reported dpa calculated values on regard of the observed crystal structure and radiation response of the ferroelectric properties is presented. (Author)

  15. Ferroelectric devices using lead zirconate titanate (PZT) nanoparticles.

    Science.gov (United States)

    Paik, Young Hun; Kojori, Hossein Shokri; Kim, Sung Jin

    2016-02-19

    We successfully demonstrate the synthesis of lead zirconate titanate nanoparticles (PZT NPs) and a ferroelectric device using the synthesized PZT NPs. The crystalline structure and the size of the nanocrystals are studied using x-ray diffraction and transmission electron microscopy, respectively. We observe PZT NPs and this result matches dynamic light scattering measurements. A solution-based low-temperature process is used to fabricate PZT NP-based devices on an indium tin oxide substrate. The fabricated ferroelectric devices are characterized using various optical and electrical measurements and we verify ferroelectric properties including ferroelectric hysteresis and the ferroelectric photovoltaic effect. Our approach enables low-temperature solution-based processes that could be used for various applications. To the best of our knowledge, this low-temperature solution processed ferroelectric device using PZT NPs is the first successful demonstration of its kind.

  16. Patterned piezo-, pyro-, and ferroelectricity of poled polymer electrets

    International Nuclear Information System (INIS)

    Qiu, Xunlin

    2010-01-01

    Polymers with strong piezo-, pyro-, and ferroelectricity are attractive for a wide range of applications. In particular, semicrystalline ferroelectric polymers are suitable for a large variety of piezo- and pyroelectric transducers or sensors, while amorphous polymers containing chromophore molecules are particularly interesting for photonic devices. Recently, a new class of polymer materials has been added to this family: internally charged cellular space-charge polymer electrets (so-called “ferroelectrets”), whose piezoelectricity can be orders of magnitude higher than that of conventional ferroelectric polymers. Suitable patterning of these materials leads to improved or unusual macroscopic piezo-, pyro-, and ferroelectric or nonlinear optical properties that may be particularly useful for advanced transducer or waveguide applications. In the present paper, the piezo-, pyro-, and ferroelectricity of poled polymers is briefly introduced, an overview on the preparation of polymer electrets with patterned piezo-, pyro-, and ferroelectricity is provided and a survey of selected applications is presented.

  17. Coexistence of weak ferromagnetism and ferroelectricity in the high pressure LiNbO3-type phase of FeTiO3.

    Science.gov (United States)

    Varga, T; Kumar, A; Vlahos, E; Denev, S; Park, M; Hong, S; Sanehira, T; Wang, Y; Fennie, C J; Streiffer, S K; Ke, X; Schiffer, P; Gopalan, V; Mitchell, J F

    2009-07-24

    We report the magnetic and electrical characteristics of polycrystalline FeTiO_{3} synthesized at high pressure that is isostructural with acentric LiNbO_{3} (LBO). Piezoresponse force microscopy, optical second harmonic generation, and magnetometry demonstrate ferroelectricity at and below room temperature and weak ferromagnetism below approximately 120 K. These results validate symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and weak ferromagnetism in a series of transition metal titanates crystallizing in the LBO structure.

  18. Two-photon spectroscopy study of edge absorption peculiarities in oxygen-octahedric ferroelectrics

    International Nuclear Information System (INIS)

    Shablaev, S.I.; Danishevskij, A.M.; Subashiev, V.K.

    1984-01-01

    Two-photon absorption (TPA) spectra of ferroelectric crystals with BaTiO 3 , KTaO 3 and SrTiO 3 perovskite strUcture Were obtained. The detailed investigation of temperature dependence of edge spectrum regions was conducted and on the basis of their analysis the indirect character of edge absorption was concluded for all mentioned crystals. TPA spectra of BaTiO 3 and KTaO 3 are characterized by the regions corresponding to one indirect edge TPA spectra of SrTiO 3 - to two indirect edges. The corresponding inter-zone gaps were determined for all investigated crystals, the energy of phonons, participating in indirect two photon transitions, inter-zone gaps, corresponding to direct transitions were determined as well

  19. Electrical characterisation of ferroelectric field effect transistors based on ferroelectric HfO2 thin films

    International Nuclear Information System (INIS)

    Yurchuk, Ekaterina

    2015-01-01

    Ferroelectric field effect transistor (FeFET) memories based on a new type of ferroelectric material (silicon doped hafnium oxide) were studied within the scope of the present work. Utilisation of silicon doped hafnium oxide (Si:HfO 2 ) thin films instead of conventional perovskite ferroelectrics as a functional layer in FeFETs provides compatibility to the CMOS process as well as improved device scalability. The influence of different process parameters on the properties of Si:HfO 2 thin films was analysed in order to gain better insight into the occurrence of ferroelectricity in this system. A subsequent examination of the potential of this material as well as its possible limitations with the respect to the application in non-volatile memories followed. The Si:HfO 2 -based ferroelectric transistors that were fully integrated into the state-of-the-art high-k metal gate CMOS technology were studied in this work for the first time. The memory performance of these devices scaled down to 28 nm gate length was investigated. Special attention was paid to the charge trapping phenomenon shown to significantly affect the device behaviour.

  20. Interplay of Cation Ordering and Ferroelectricity in Perovskite Tin Iodides: Designing a Polar Halide Perovskite for Photovoltaic Applications

    Energy Technology Data Exchange (ETDEWEB)

    Gou, Gaoyang; Young, Joshua; Liu, Xian; Rondinelli, James M.

    2016-09-28

    Owing to its ideal semiconducting band gap and good carrier transport properties, the fully inorganic perovskite CsSnI3 has been proposed as a visible-light absorber for photovoltaic (PV) applications. However, compared to the organic inorganic lead halide perovskite CH3NH3PbI3, CsSnI3 solar cells display very low energy conversion efficiency. In this work, we propose a potential route to improve the PV properties of CsSnI3. Using first-principles calculations, we examine the crystal structures and electronic properties of CsSnI3, including its structural polymorphs. Next, we purposefully order Cs and Rb cations on the A site to create the double perovskite (CsRb)Sn2I6. We find that a stable ferroelectric polarization arises from the nontrivial coupling between polar displacements and octahedral rotations of the SnI6 network. These ferroelectric double perovskites are predicted to have energy band gaps and carrier effective masses similar to those of CsSnI3. More importantly, unlike nonpolar CsSnI3, the electric polarization present in ferroelectric (CsRb)Sn2I6 can effectively separate the photoexcited carriers, leading to novel ferroelectric PV materials with,potentially enhanced energy conversion efficiency.