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Raman scattering spectra in single crystals of lithium tantalate at 180-degree scattering geometry in a wide spectral frequency range (50 ÷ 2800 cm−1) were studied. Raman peaks were found in 1300 ÷...

A transformation of the initial three-layer domain structure in lithium tantalate with composition gradient and formation of charged domain wall (CDW) under application of ac electric field have be...

We considered the experimentally observed variety of domain shapes in crystals of lithium niobate and lithium tantalate family. The shapes were classified, and their formation was discussed in term...

The initial domain structure was investigated in Z-cut plates of lithium tantalate crystal with various spatially nonuniform distributions of Li concentration along the polar axis formed by...

The domain structure formation in the congruent lithium tantalate single crystals after IR laser irradiation by linear scanning of Z + polar surface has been studied. Two types of domain structures...

The bulk screening being the only possibility for decreasing residual depolarization field and stabilizing tailored domain structures is one of the main factors defining the domain kinetics...

Lithium tantalate is a well-known optical crystal. The dispersion relation of phonon-polaritons was studied in ferroelectric lithium tantalate crystals. The reflectivity spectra of E//x and...

The formation of domain arrays and domain wall shape instability induced by ion beam irradiation have been studied in congruent lithium tantalate crystal covered by dielectric layer. The dependences of domain radii on exposure dose and array period were obtained. The domain wall shape instability effect (appearance of periodical oriented fingers) for doses above 20 pC was revealed. It was shown that dose increase led to increase of total length of the domain wall with fingers, while the finger number remained approximately constant. The observed results were explained by the kinetic approach based on analogy with first order phase transitions.

Growth of LiTaO3 film on a type-p silicon substrate (100) was conducted using the Chemical Solution Deposition (CSD) and spin coating methods at a speed of 3000 rpm for 30 seconds. The film on the ...

A new concept of pyroelectric electrohydrodynamic system for deposition of the micron size droplets at the predetermined position on the substrate with high accuracy using pyroelectric field created by lithium tantalate with tailored domain structure has been proposed. The optimal geometry of the domain pattern has been obtained by computer simulation of the spatial distribution of surface pressure acting on liquid/vapor interface induced by pyroelectric field. The proposed technique was applied to dispense the silicon oil and the water solution of amino acid glycine.

Imaging of ferroelectric domains using scanning electron microscopy is challenging as ferroelectrics are usually highly insulating. However, micro and nanodomain patterns can be directly visualized in secondary electrons using proper parameters. Low accelerating voltage or local charge compensation allows visualizing isolated domains with sizes above 100 nm without any sample preparation. Nanodomain patterns can be visualized with resolution about 3 nm after proper preparation of the sample surface: controlled chemical etching to obtain nanoscale surface relief and subsequent covering of the crystal surface by conductive film. Features of visualization of various nanodomain structures by scanning electron microscopy are considered.

The present article investigates the characteristic of moving load and effect of irregularity, hydrostatic stress, and magneto-elastic coupling parameter on the stresses developed due to moving load on the surface of an irregular magneto-elastic monoclinic half-space subjected to the friction associated with a rough surface. Boundary conditions are listed for which corresponding analyses can be performed analogously. The expressions for stresses are obtained analytically. Numerical computation of the obtained results are carried out for three different materials with monoclinic symmetry (lithium niobate, lithium tantalate, and quartz); the significant effects of affecting parameters on these relations are distinctly marked by means of graphs.

In the paper we review the self-organized formation of exotic dendrite-shape domain structures in ferroelectric single crystals. The main attention is paid to our recent detail experimental study of the dendrite domain growth during polarization reversal in stoichiometric lithium niobate LiNbO3 at elevated temperature and in congruent lithium tantalate LiTaO3 after pulse laser heating. Optical, confocal Raman, scanning electron, and piezoelectric force microscopy have been used for domain visualization at the surface and in the bulk. The key roles of isotropic domain growth at elevated temperature, correlated nucleation effect, and ineffective screening of the depolarization field have been revealed.

The switching in the bulk only in lithium tantalate single crystals with modification of the surface layer by short-time low energy ion irradiation has been studied experimentally. It was shown by us earlier that in lithium niobate single crystals such irradiation led to spatially inhomogeneous increase of the bulk conductivity and allowed us to create by polarization reversal the stable domain structure with charged domain walls. In this paper, we compare the features of the domain structure evolution and growth of the charged domain walls in modified crystals of lithium tantalate and lithium niobate.

The polarization reversal was studied in single crystals of lithium tantalate with intermediate deviation from stoichiometric composition (([Li]/([Li]+[Ta]) = 48.9%) with and without surface photoresist layer. The switching current was analyzed according to the stages of domain structure evolution revealed during in situ visualization of domain kinetics. The characteristic times of the switching process were extracted by fitting of the experimental data using modified Kolmogorov-Avrami model. The formation of the self-assembled domain chains was observed during polarization reversal with photoresist dielectric layer on one polar surface.

Formation of the micro- and nanodomain structures in congruent lithium tantalate single crystal under the action of pyroelectric field induced by pulse infrared laser irradiation at elevated temperatures was investigated. Three types of the self-organized domain structures were obtained: (1) the self-similar domain structure formed in crystal regions heated below Curie temperature, (2) the maze-type domain structure, and (3) irregular-shaped isolated domains formed in the regions heated above Curie temperature. The results of calculation of the time dependent spatial distribution of the temperature and pyroelectric field have been used for explanation of the peculiarities of domain structure formation.

The electronic conductivity was measured in single crystals of lithium niobate and lithium tantalate family at elevated temperatures using direct electrometric method with original technique of compensation of pyroelectric current. Experimentally measured temperature dependences of the bulk electrical conductivity along the polar direction followed the Arrhenius law with activation energy ranging from 1.0 to 1.2 eV. It was shown that bulk intrinsic conductivity became the main mechanism of screening at the temperatures above 160°C. The conductivity anisotropy was studied in MgOLN single crystals.

Undoped, 5%, and 10% lanthanum doped lithium tantalate thin films were annealed at 550°C temperature for 12.5 hours and their properties were characterized. The results showed that the dopant addition affects the crystal formation of LiTaO3, especially the 10% La2O5 dopant, where the lattice of a = 5.11 A, c = 13.30 A, and its crystal was hexagonal. The observed functional groups were O-H, N-H, C = C, Li-O, Ta-O. The higher La2O5 dopant concentration leads to the higher absorption of Ta-O and Li-O, the lower the energy gap, the higher the refractive index, and the smaller the particle size of thin films.

Stoichiometric lithium tantalate (SLT) powder was prepared by a solid-state combustion method from the raw powder of Li2CO3, Ta2O5, and urea, which is characterized by a short reaction time and relatively low temperatures. The urea, added into the mixture (Li2CO3 and Ta2O5), serves as a fuel and an inducer to produce intermediate compounds and cause a solid-state combustion reaction as well. Various temperatures and urea contents were employed to optimize the synthesis of SLT. The chemical process and the quality of LiTaO3 powder were investigated by X-ray diffraction, electron microscope, thermogravimetry, and Raman spectroscopy. The optimized synthesis shows great capability to reduce the volatilization of lithium-ion and presents an efficient way to manufacture high-quality SLT.

The active substrates with rings of silver nanoparticles arising by drying of sessile colloid drops were used for realization of the surface-enhanced Raman scattering. The colloids have been produced by laser ablation in water using pulse Yb fiber laser. The droplets with diameter down to 10 μm were dispensed by electrohydrodynamic technique by means of pyroelectric field produced by lithium tantalate plate. The optimal spatial distribution of hotspots was obtained for substrate covered by the micron-size rings of silver nanoparticles. The method was applied for various organic molecules rhodamine 6G, thymine, and RNA with enhancement factor up to 105.

The polarization reversal process has been studied in 8 mol.% MgO doped congruent lithium tantalate single crystal using in situ domain visualization and analysis of the switching current data based on original modification of the Kolmogorov-Avrami approach. Two revealed stages of domain structure evolution during cyclic switching representing slow growth of isolated domains and fast motion of macroscopic domain walls were taken into account during analysis of the switching current data. The coercive field for quasi-static switching about 1.2 kV/mm was revealed. The main parameters of the switching process have been compared with other representatives of lithium tantalate family.

The droplet generation under the action of the pyroelectric field created by uniform heating or cooling of the monodomain lithium tantalate plate was studied. The droplets of dielectric and conductive liquid with the volume below picoliter have been deposited on glass substrate with good reproducibility. It was shown that the drying of the dispensed colloid droplets allowed producing the uniform circular and ring-like micron-size patterns of Ag nanoparticles on the substrate. The numerical simulation of attractive force induced by pyroelectric field which is applied to the drop allowed us to explain the obtained results.

The formation of self-organized structures of submicron domains under application of the uniform electric field was studied in single crystals of magnesium doped near stoichiometric lithium tantalate grown by double crucible Czochralski method. It was shown that the period of the domain structure (about 1 μm) appeared on Z− polar surface after polarization reversal was almost independent on the electric field. This fact confirms the self-organized nature of the phenomenon. The obtained dependence of the structure geometry on the switching conditions was discussed. The noticeable increase of the low-frequency dielectric permittivity was demonstrated in the samples with charged domain walls.

Formation of nanodomain structures during cooling after pulse heating by infrared laser has been studied in congruent lithium tantalate (CLT) and lithium niobate (CLN) single crystals. In situ study of the domain structure evolution allowed to reveal that in CLN the isolated domains appeared at the edges of the irradiated zone and grew to the center. In contrast, the quasi-regular stripe domain structure appeared in CLT near the edge of irradiated zone. The difference has been attributed to lower Curie temperature and larger pyroelectric coefficient of CLT. The self-organized domain structures can be used for periodical poling with submicron periods.

International audience; This study presents an examination of the temperature influence of an EO-modulation system on the basis of its thermo-optic (TO) behavior. We have considered the first order contribution of the temperature to the EO modulator response with emphasis on the direct influence of temperature on the birefringence and on the dimensions of the active part existing between both electrodes. The role of the transverse configuration is examined in comparison with its corresponding longitudinal configuration. Finally, we illustrate this work using some significant results obtained with a lithium tantalatemodulator crystal, which is considered as a promising material for EO modulation applications.

In the present paper we report the first results of the study of the polar state of the surface structure of single crystal of potassium tantalate doped with Li + ions (KLT-3%) by the piezoresponse force microscopy technique in the temperature range 10–295 K. The results obtained demonstrate the existence of polar nanoregions on the surface of the KLT-3% single crystal at temperatures 10 – 80 K. Spatial distribution and temperature evolution of these polar nanoregions are analyzed. Observation of the structure of polar nanoregions of KLT-3% crystal in zero field heating after zero field cooling regime gives the evidence of the existence of spontaneous polarization in the low-temperature phase.

The recent achievements in domain nanotechnology in single crystals of lithium niobate and lithium tantalate family have been reviewed. The formation of nanoscale domain structures has been studied with high spatial resolution using modern experimental methods of domain visualization. Criteria of the investigated ferroelectric material selection and recent experimental achievements have been presented. The physical basis of the nanodomain engineering based on the role of nanoscale domains in formation of the domain patterns in highly non-equilibrium switching conditions has been discussed. The obtained knowledge allows us to manufacture the highly efficient periodically poled crystals for laser light frequency conversion.

Formation of the micro- and nanodomain structures under the action of pyroelectric field induced by pulse IR laser heating was studied in congruent lithium tantalate. Two types of the self-organized domain structures were found. The three-dimensional maze-type structure with average period about 100 nm appeared in the central part of the irradiated zone heated above Tc. The self-similar structure of oriented domain rays with nanoscale width formed at the edge of the irradiated zone. The obtained increase of the average distance between the nanodomain rays for irradiation at the elevated temperatures was attributed to the decrease of the pyroelectric field.

Ceramics of Li0.98-x Ta1.004-x/5 O3 solid solutions with 0 ≤ × ≤ 0.20 are studied by a new theoretical approach. From the experience, we have proposed the new vacancy models which are able to describe substitutional mechanism in Ni-doped lithium tantalate. Theoretical approach combined with generalised vacancy models allows us to establish a new expression of electrical conductivity which takes into account the defect structure of Ni-doped lithium tantalate. Calculation of the Curie temperature in Ni-doped non stoichiometric lithium tantalate reveals good correspondence with experimental results.

The polarization reversal has been studied in congruent single crystalline lithium tan-talate, LiTaO3, in temperature range from room temperature to 250°C. The fitting of the switching current data by modified Kolmogorov-Avrami formula allowed to reveal the main stages of the polarization reversal and to propose the original method of the threshold field measuring. The two times decrease of the threshold field was observed for 250°C. Essential change of the domain kinetics and shape of isolated domains at both polar surfaces was observed at temperatures above 200°C. The observed facts were attributed to effective bulk screening due to bulk conductivity increase. Copyright © Taylor & Francis Group, LLC.

Layers from tens to hundreds of microns thick of a different phase composition and stoichiometry are shown to form in lithium tantalate crystals subjected to treatment by vapor transport equilibration in lithium vapour. The 500 microns thick stoichiometric (Li/Ta ≈ 1) layers have ten times lower values of the coercive field compared with congruent lithium tantalate. As electrical measurements suggest, a new polar structure of phase transition at ∼120°C is possibly formed within a thin (30 μm) surface layer of the lithium tantalate sample after vapour transport equilibration treatment.

Single crystals K0.95Li0.05Ta1-x Nb x O3 (KLTN) - x = 0.6 are grown and the transmission spectra show the UV absorption edge is about 400 nm for the transparent KLTN crystal sample. The refractive index and the frequency dependent of linear electro-optic coefficients of KLTN single crystals in the tetragonal phase are characterized at room temperature. The minimum deviation method is used for the refractive index measurements and the electro-optic properties have been investigated using the senarmont method and the auto scanning mach-zehnder interferometer technique. The EO measurements were taken with the continuous low frequency of applied ac field from 100 Hz to 100 KHz. Large electro-optic responses are observed and the coefficients, γ33 = 216.7 pm/V, γ13 = −21.2 pm/V, and γc = 242.9 pm/V at 1 kHz are measured for the crystals. The E-O properties show that the high quality KLTN single crystals have the potential in the field of optical modulation and deflection field devices.

The vapour transport equilibration (VTE) is used to change the Li/Ta ratio in lithium tantalate single crystals of different crystallographic orientations (Z-cut and Y/128°-cut). Treatment by VTE is shown to provide thin layers in lithium tantalate plates composition of which is close to stoichiometric while the values of the coercive field are different, much smaller compared with congruent single crystals. There are several mechanisms of diffusion of the Li+ ions in LiTaO3 under conditions of VTE the contribution of each being dependent on the crystallographic orientation of the sample.

An electric field controlled two-dimensional higher order diffraction optical beam splitter has been realized based on a photorefractive higher order diffraction grating. In experiments, the splitter was produced by wave coupling (632.8 nm, 532.0 nm) at a small incident angle with a potassium lithium tantalate niobate single crystal. In the process of splitting, the incident beam of different wavelengths (632.8 nm, 532.0 nm) could be split into multi-output beams by the splitter. The influence of an externally applied electric field was studied and results show that the intensity of higher order diffraction could be controlled by the electric field. The polarization properties of higher order diffraction were discussed. An electric field controlled five–three optical beam splitter was investigated theoretically.

The recent achievements in study and interpretation of the formation of self-assembled nanodomain structures in the single crystals of lithium niobate and lithium tantalate under the highly non-equilibrium switching conditions have been reviewed. The experimentally used switching conditions include: 1) spontaneous backswitching, 2) modification of the surface layers, and 3) pulse laser irradiation. Various evolution scenarios of nanoscale structures consisting of the oriented chains of isolated nanodomains and the growth of nanodomain rays have been revealed and discussed. It is confirmed that the screening ineffectiveness and switching field value unambiguously determined the proper scenario of domain evolution.

In this work, a set of local electron irradiations has been used to fabricate domain gratings in conventional lithium tantalate crystals. The Z and Y-cuts of the crystals were irradiated in the SEM at 25 kV, using different distributions of square point writing by an e-beam. Peculiarities of the domain-inverted gratings that were located near the surface of the Y- cuts and in the crystal bulk of the Z-cuts have been investigated at the different drawing motives, doses of irradiations and crystallographic directions of e-beam movement during writing. The domain structures were examined in optical microscopes after chemical etching of the irradiated samples. The crystallographic Y directions were found to be important in e-beam drawing on Z-cut surfaces. Account should be taken of the crystallographic Z direction during e-beam writing and long domain-inverted grating fabrication on the Y-cuts. For both polar cuts, the reduction of intervals between the sequences of local irradiated areas down to 2–3 μm was ...

Kinetics of bulk screening of depolarization field was studied in single crystalline lithium niobate and lithium tantalate of various compositions by analysis of the switching current, birefringence contrast, and diffraction of coherent light on the domain walls. The bulk screening process was quantitatively characterized by several essential parameters, such as a type of relaxation law, relaxation time constants, and maximum value of bulk screening field. Advantages and disadvantages of used experimental methods were discussed. The comparison of the obtained and previously published results was carried out.

Micro and nano-scale domain structures were revealed in the surface layer of the Y-cuts in congruent LiTaO 3 crystals by point electron beam drawing in a scanning electron microscope. The various periodic domain structures were formed by point e-beam irradiation with different distances between the points along the X and Z directions in the Y-cuts. The dependence of domain continuity on the e-beam jump direction at the drawing was observed. Peculiarities of the switching of spontaneous electric polarization on the Y-cuts were investigated at different point doses and the point arrangements during electron beam drawing.

A method for modifying the surface free energy of lithium tantalate ferroelectric crystals is reported. Ultraviolet illumination and low-energy electron irradiation have been used for tuning the surface free energy resulting in a wide range of wettability contact angles. The UV illumination makes the crystal polar face superhydrophilic while the electron irradiation strongly decreases the surface wetting. Basic thermodynamic approaches such as Zisman, Owens-Wendt, and Van Oss-Chaudhury-Good have been applied to calculations of elementary interactions responsible for bonding of solids. Fabrication of various wetting configurations allows to demonstrate high quality direct bonding of lithium tantalate plates with hydrophilic polar faces.

LiTaO 3 thin films were deposited on RuO 2 electrode by RF magnetron sputtering with a Li 2 O 2 /Ta 2 O 5 (50%–50%) target. This article presents a morphological, structural, dielectric and pyroelectric study of LiTaO 3 thin films. The originality of this work resides on the choice of the substrate: silicon nitride on Si (SiN x /Si) membrane. The final aim is to improve the pyroelectric coefficient for infrared pyroelectric detectors applications. The best pyroelectric coefficient of LiTaO 3 thin films (400 nm) is equal to 60 μC/m 2 K. It was obtained for deposited temperature of 400°C, and a pressure of 10 mTorr.

Testing representations of inhomogeneous composition of 36°Y-X LiTaO3 single crystal for SAW devices are investigated using HRTAXRD and elaborate structure of infrared absorption spectrum of OH-stretch mode in 3450–3550 cm− 1, contrasting them with Curie temperature (Tc) and ultraviolet absorption edge. Lineshape and relative intensity of OH spectrum vary with composition inhomogeneity of sample. Change of Lattice constants by HRTAXRD is sensitive. Change of constant “c” is more conceivable rather than “a” and Local scan with 32 times of OH spectrum in 3450–3550 cm− 1 are more intuitionistic than T c and UV absorption edge to reflect inhomogeneity by Li deficiency. Results of various method adopted are approved each other.

Static domain patterns produced by application of the external electric field in single crystals of congruent, stoichiometric and MgO doped lithium niobate LiNbO3 (LN) and lithium tantalate LiTaO3 (LT) were investigated experimentally. The study of the domain kinetics by computer simulation and by switching of the model structure showed applicability of the kinetic approach to explanation of the experimentally observed evolution of domain shape and domain structure.The step-by-step domain growth was realized during the model experiment. The evolution of two-dimensional (2D) domain patterns produced by application of external electric field using lithographic 2D electrode grating has been investigated in congruent LN. It was shown that the domain kinetics is governed by merging of individual domains and the formed macro-scale domains are similar to the ones obtained in real samples including full variety of shapes from triangles to hexagons and even concave ones. The domain shape details were easily distinguished by optical microscopy for used 10-μm-period grating.Computer simulation in terms of cellular automata using simple local switching rules for step-by-step domain growth allows us to obtain the domain patterns very similar to the domain images observed experimentally. Proposed kinetic model allows US to explain all of observed domain shapes both in macro-and micro-scales. It was shown that the domain shape is strongly affected by such experimental conditions as electric field pulse parameters and screening properties. Several original scenarios of the domain structure evolution were revealed experimentally and the decisive role of the retardation of the screening process was clearly demonstrated.It was shown that the domain evolution during decay of the highly-nonequilibrium state represents a self-organizing process, in which the screening plays the role of feedback during polarization reversal. For short electric pulses the screening is ineffective and uncompensated depolarization field drastically change the domain kinetics thus producing the equidistant arranged arrays of small sub-micron (nanoscale) domains.

Polarization-reversed optical (PRO) devices in ferroelectric LiNbO3 (LN) and LiTaO3 (LT), and non-ferroelectric crystal quartz are reviewed. Efficient wavelength converters to mid-infrared and visible light and a low-frequency-chirp intensity modulator for high-speed fiber communication are demonstrated with polarization-reversed structures. Spatial modulation of second-order susceptibility opens a new window to functionalize conventional materials, and will pave a road to integrated optical devices.

The investigation of the local polarization switching including direct domain writing, local hysteresis measurements, and domain stability testing was carried out in single-crystalline stoichiometric lithium tantalate using the Scanning Probe Microscope. Piezoresponse Force Microscopy was utilized for domain visualization and recording of local switching characteristics. Two variants of domain patterning were shown: “direct writing” and “self-assembled formation.” The polarization reversal in direction opposite to applied field (“anti-parallel switching”) was studied in details and attributed to screening of external field.

The main aspects of domain engineering in LiNbO 3 and LiTaO 3 representing field induced formation of the tailored domains are discussed. The special attention is paid to sideways domain wall motion. Experimentally observed wall motion scenarios have been classified. It is discovered that the realization of the given scenario is defined by degree of deviation of the switching conditions from equilibrium characterized by ratio between switching and screening rates. It has been proved that the domain growth acceleration after merging is due to formation of super-fast X-oriented walls. The loss of wall shape stability and formation of nano-domains have been considered.

A shear horizontal-mode surface acoustic wave (SH-SAW) has the unique characteristic of complete reflection at a free edge normal to the direction of propagation, making it possible to construct a reflective delay line. A passive SAW strain sensor based on such a reflective delay line is presented. The reflective delay line is constructed on a 36° YX LiTaO 3 substrate. The SH-SAW velocity is shown to provide a reliable measure of the strain of a propagation surface, and incorporation of an oscillator circuit is demonstrated to allow wireless remote monitoring of strain using this sensor.

Among various lithium tantalate family ceramic solid solution systems, the ceramic material where a part of LiTaO3 was substituted by CaTiO3, seemed worth noticing because of its highly sintered desity more than 97% and excellent electrical properties at high temperatures which make it possible to be poled. In the solid solution system, (1 - x)LiTaO 3--xCaTiO3, 0 ≤q x ≤q 0.2, Curie temperature, identified from the dielectric maximum, was lowered with increasing amounts of x value with an approximate rate of 16°C/mol%. Corresponding to the phase diagram of Li2 O-Ta2O5 system, where LiTaO3 phase spreads from the stoichiometric composition toward Ta-rich direction, stable solid solution ceramics were obtained in a little Ta or Ti-rich composition. Lamb wave was successfully generated and detected in a ceramic attached with a pair of arch shaped interdigital transducers with an insertion loss of 30 dB.

Experimental and analytical study of the Curie temperature and density for different compositions of nonstoichiometric lithium tantalate are presented in this work. Our results show that the Curie temperature decreases and the density increases linearly with increasing composition. Using the theoretical approach to the defect structure analysis, developed by Safaryan, a comparison between three defects models (oxygen vacancies, tantalate vacancies and lithium vacancies) has been proposed. The calculated and measured values show that the lithium vacancy model effectively describes the defect structure in nonstoichiometric lithium tantalate. The experimental procedures employed indicate that the errors in the formulae obtained have been estimated to be about 0.8% for Li, 1% for Ta and in the crystal parameters they have been estimated to be about 0.001 A for a and 0.005 A for c. Communicated by Dr. George W. Taylor

Ferroelectrics have created considerable interest as promising storage media. In this paper, an investigation for ultra high-density ferroelectric data storage based on scanning nonlinear dielectric microscopy (SNDM) was carried out. For the purpose of obtaining the fundamental knowledge of high-density ferroelectric data storage, several experiments of nano-domain formation in lithium tantalate (LiTaO3 ) single crystal were conducted. As a result, domain dot array with areal density of 1.5 Tbit/inch2 was written in congruent LiTaO3 (CLT). We also found that quite fast nano second domain switching was possible by reducing a sample thickness even in CLT with a lot of Li vacancy defects which played a role of pinning sites against domain wall movement.

As a part of sequential work developing new lead-free piezoelectric ceramics, the solid solution system (1-x)LiTaO3–xCaTiO3, 0 ≤ x ≤ 0.20, has been investigated. Samples sintered at 1250°C for 5 h in air have resulted in dense and white ceramics with single phase lithium niobate structure. The Curie temperature of LiTaO3 was lowered with increasing CaTiO3 content, accompanying with a feature of diffused phase transition. The ceramics showed clear vibration resonance in radial and thickness modes.