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Lithium tantalate (LT) exhibits nonlinear optical properties that are comparable to those of lithium niobate (LN), yet the former surpasses the latter in several respects. These include an enhanced optical damage threshold, a wider transparency range, and lower birefringence. Consequently, LT is an excellent material for optical frequency conversion applications. In this study, we have devised a novel device based on thin-film lithium tantalate (TFLT) for the efficient generation of second-harmonic waves. The design employs modal phase-matching (MPM), which circumvents the intricacies of conventional poling techniques, and attains a normalised conversion efficiency of 120% W−1cm−2. In order to address the challenges presented by higher-order modes, a mode converter with an insertion loss of less than 0.1 dB has been developed, thereby ensuring the efficient utilisation of the second harmonic. This study not only demonstrates the potential of TFLT for high-performance SHG, but also promotes the development of integrated nonlinear TFLT platforms. [ABSTRACT FROM AUTHOR]

The fabrication of stable, tailored domain patterns in ferroelectric crystals has wide applications in optical and electronic industries. All-optical ferroelectric poling by pulse laser irradiation has been developed recently. In this work, we studied the creation of the domain structures in MgO-doped lithium tantalate by focused irradiation with a femtosecond near-infrared laser. Cherenkov-type second harmonic generation microscopy was used for domain imaging of the bulk. We have revealed the creation of enveloped domains around the induced microtracks under the action of the depolarization field. The domain growth is due to a pyroelectric field caused by a nonuniform temperature change. The domains in the bulk were revealed to have a three-ray star-shaped cross-section. It was shown that an increase in the field excess above the threshold leads to consequential changes in domain shape from a three-ray star to a triangular and a circular shape. The appearance of comb-like domains as a result of linear scanning was demonstrated. All effects were considered in terms of a kinetic approach, taking into account the domain wall motion by step generation and kink motion driven by excess of the local field over the threshold. The obtained knowledge is useful for the all-optical methods of domain engineering in ferroelectrics. [ABSTRACT FROM AUTHOR]

We report a new and more precise Sellmeier equation obtained by using the analysis of quasi-phase-matching curves of the optical parametric generation (OPG) in 1D periodically poled LiTaO3 (1D-PPLT) of different grating periods. [ABSTRACT FROM AUTHOR]

Lithium tantalate (LiTaO3) perovskite finds wide use in pyroelectric detectors, optical waveguides and piezoelectric transducers, stemming from its good mechanical and chemical stability and optical transparency. Herein, we present a method for synthesis of LiTaO3 nanoparticles using a scalable Flame Spray Pyrolysis (FSP) technology, that allows the formation of LiTaO3 nanomaterials in a single step. Raman, XRD and TEM studies allow for comprehension of the formation mechanism of the LiTaO3 nanophases, with particular emphasis on the penetration of Li atoms into the Ta-oxide lattice. We show that, control of the High-Temperature Particle Residence Time (HTPRT) in the FSP flame, is the key-parameter that allows successful penetration of the -otherwise amorphous- Li phase into the Ta2O5 nanophase. In this way, via control of the HTPRT in the FSP process, we synthesized a series of nanostructured LiTaO3 particles of varying phase composition from {amorphous Li/Ta2O5/LiTaO3} to {pure LiTaO3, 15–25 nm}. Finally, the photophysical activity of the FSP-made LiTaO3 was validated for photocatalytic H2 production from H2O. These data are discussed in conjunction with the role of the phase composition of the LiTaO3 nanoparticles. More generally, the present work allows a better understanding of the mechanism of ABO3 perovskite formation that requires the incorporation of two cations, A and B, into the nanolattice. [ABSTRACT FROM AUTHOR]

Lithium tantalate crystals, as a type of pyroelectric material, stand out from many other pyroelectric materials due to the advantages of high Curie temperature, large pyroelectric coefficient, high figure of merits, and environmental friendliness. Due to the pyroelectric effect caused by their spontaneous polarization, lithium tantalate crystals have broad application prospects in wide spectral bandwidth and uncooled pyroelectric detectors. This article reviews the pyroelectric properties of lithium tantalate crystals and evaluates methods for pyroelectric properties, methods for modulating pyroelectric properties, and pyroelectric detectors and their applications. The prospects of lithium tantalate thin films, doped lithium tantalate crystals, and near stoichiometric lithium tantalate crystals as response components for pyroelectric detectors are also discussed. [ABSTRACT FROM AUTHOR]

Lithium tantalate (LT) exhibits nonlinear optical properties that are comparable to those of lithium niobate (LN), yet the former surpasses the latter in several respects. These include an enhanced optical damage threshold, a wider transparency range, and lower birefringence. Consequently, LT is an excellent material for optical frequency conversion applications. In this study, we have devised a novel device based on thin-film lithium tantalate (TFLT) for the efficient generation of second-harmonic waves. The design employs modal phase-matching (MPM), which circumvents the intricacies of conventional poling techniques, and attains a normalised conversion efficiency of 120% W−1cm−2. In order to address the challenges presented by higher-order modes, a mode converter with an insertion loss of less than 0.1 dB has been developed, thereby ensuring the efficient utilisation of the second harmonic. This study not only demonstrates the potential of TFLT for high-performance SHG, but also promotes the development of integrated nonlinear TFLT platforms.

Near-stoichiometric lithium tantalate (NSLT) wafers with different Li contents were prepared by vapour transfer equilibrium (VTE) method and fabricated into surface acoustic wave filters. The temperature coefficient of frequency, insertion loss, and bandwidth of the surface acoustic wave filters were tested using a special chip test bench and a network analyzer. The results show that the temperature coefficient of frequency shows a trend of first decreasing and then increasing with the increase in Li content, and the temperature stability of the surface acoustic wave filters is best when the Li content is 49.75%. It is also found that the surface acoustic wave filter fabricated from NSLT wafers has 21.18% lower temperature coefficient of frequency, 7.3% lower insertion loss, and 2.8% lower bandwidth than those fabricated from congruent lithium tantalate wafers. Therefore, NSLT crystals are more suitable for applications in acoustic devices, providing a new idea for performance enhancement of 5G communication devices. [ABSTRACT FROM AUTHOR]

Poling and structuring of ferroelectric domains form the basis for developing prospective applications using materials from the lithium‐niobate (LN) family. Applications range from second harmonic generation to electro‐optic modulators or surface acoustic wave devices. In the work presented here, hysteresis measurements are used as a standard method to quantitatively determine the poling properties of these ferroelectrics, including their spontaneous polarization Ps as well as their forward and reverse coercive fields Ec,+ and Ec,−. Systematic measurements that depend on parameters such as the ramp rate R of the applied poling voltage and the waiting time twait between domain inversions are investigated and compared between the congruent variants of LN, lithium tantalate (LT), their magnesium‐doped analogues, and stoichiometric LN. For bulk magnesium‐doped LN, for example, it is found that the resulting coercive field strongly depends on the speed of the voltage ramp, with Ec$E_{\text{c}}$ values ranging from 11 to 21 kV mm−1. These investigations are used as fundamental input for poling ferroelectric lithium niobate‐tantalate solids (LNT), a system that offers a high potential for tuning the material parameters beyond what is possible for LN or LT. [ABSTRACT FROM AUTHOR]

The fabrication of stable, tailored domain patterns in ferroelectric crystals has wide applications in optical and electronic industries. All-optical ferroelectric poling by pulse laser irradiation has been developed recently. In this work, we studied the creation of the domain structures in MgO-doped lithium tantalate by focused irradiation with a femtosecond near-infrared laser. Cherenkov-type second harmonic generation microscopy was used for domain imaging of the bulk. We have revealed the creation of enveloped domains around the induced microtracks under the action of the depolarization field. The domain growth is due to a pyroelectric field caused by a nonuniform temperature change. The domains in the bulk were revealed to have a three-ray star-shaped cross-section. It was shown that an increase in the field excess above the threshold leads to consequential changes in domain shape from a three-ray star to a triangular and a circular shape. The appearance of comb-like domains as a result of linear scanning was demonstrated. All effects were considered in terms of a kinetic approach, taking into account the domain wall motion by step generation and kink motion driven by excess of the local field over the threshold. The obtained knowledge is useful for the all-optical methods of domain engineering in ferroelectrics.

In the current work, nanocrystalline powders with different compositions, namely Li0.98Pr0.02NbO3, Li0.93Pr0.02Mg0.05NbO3 and Li0.98Pr0.02TaO3 were synthesized for the first time using the method of high-energy ball milling of the starting materials (Li2CO3, Nb2O5, Ta2O5, MgO, Pr6O11), followed by high-temperature annealing. XRD data analysis confirmed the absence of parasitic phases in the obtained nanocrystalline compounds. The estimated particle sizes ranged from 20 to 80 nm. From the obtained nanopowders, ceramic samples were prepared using specially developed equipment, which allowed for pressing at elevated temperatures with a simultaneous application of a constant electric field. The obtained photoluminescence spectra exhibit characteristic features of Pr3+ ions in the crystal structure of LiNbO3 and LiTaO3 and are most efficiently excited by UV light. Samples pressed with an electric field application show higher intensity of photoluminescence. Investigations of the temperature dependence of electrical conductivity of the Li0.98Pr0.02NbO3 sample, pressed with the application of an electric field, indicate that the conductivity mechanism is similar to that of LiNbO3 single crystals and, at high temperatures, is attributed to the lithium conduction mechanism.

Lithium tantalate crystals, as a type of pyroelectric material, stand out from many other pyroelectric materials due to the advantages of high Curie temperature, large pyroelectric coefficient, high figure of merits, and environmental friendliness. Due to the pyroelectric effect caused by their spontaneous polarization, lithium tantalate crystals have broad application prospects in wide spectral bandwidth and uncooled pyroelectric detectors. This article reviews the pyroelectric properties of lithium tantalate crystals and evaluates methods for pyroelectric properties, methods for modulating pyroelectric properties, and pyroelectric detectors and their applications. The prospects of lithium tantalate thin films, doped lithium tantalate crystals, and near stoichiometric lithium tantalate crystals as response components for pyroelectric detectors are also discussed.

In the current work, nanocrystalline powders with different compositions, namely Li0.98Pr0.02NbO3, Li0.93Pr0.02Mg0.05NbO3 and Li0.98Pr0.02TaO3 were synthesized for the first time using the method of high-energy ball milling of the starting materials (Li2CO3, Nb2O5, Ta2O5, MgO, Pr6O11), followed by high-temperature annealing. XRD data analysis confirmed the absence of parasitic phases in the obtained nanocrystalline compounds. The estimated particle sizes ranged from 20 to 80 nm. From the obtained nanopowders, ceramic samples were prepared using specially developed equipment, which allowed for pressing at elevated temperatures with a simultaneous application of a constant electric field. The obtained photoluminescence spectra exhibit characteristic features of Pr3+ ions in the crystal structure of LiNbO3 and LiTaO3 and are most efficiently excited by UV light. Samples pressed with an electric field application show higher intensity of photoluminescence. Investigations of the temperature dependence of electrical conductivity of the Li0.98Pr0.02NbO3 sample, pressed with the application of an electric field, indicate that the conductivity mechanism is similar to that of LiNbO3 single crystals and, at high temperatures, is attributed to the lithium conduction mechanism. [ABSTRACT FROM AUTHOR]

In this work, we studied the pyroelectric activity of thin polycrystalline lithium niobate films fabricated by radio frequency magnetron sputtering and laser ablation, and thin polycrystalline lithium tantalate films fabricated by radio frequency magnetron sputtering. Using the dynamic method of studying the pyroelectric effect, it was found that all samples have self-polarization that occurs during the post-growth thermal annealing of the structure. An estimate of the pyroelectric coefficient showed that the values of the pyroelectric coefficient of lithium niobate and lithium tantalate thin films are several times lower than the values of the pyroelectric coefficient for bulk crystals of the corresponding materials. This may be due to the fact that the polarization vector of some grains lies in the film plane, as well as to the traps existing in the film volume and at the film/substrate interface, on which charge carriers recombine and do not participate in the generation of the pyroelectric current.

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Lithium tantalate (LiTaO3, or LT) crystal is widely used in optical applications, infrared detection, and acoustic surface wave devices because of its excellent piezoelectric, pyroelectric, and nonlinear optical properties. In this paper, we discuss the defect structure of LT; the preparation method for LT; the influence of doping on LT; and LT's application in optical, acoustic, and electrical devices. We mainly analyzed the structure and physical properties of LT crystal, the preparation of LT crystal and LT thin films, the periodic polarization of LT crystal, the reduction of LT wafers, and the application potential of LT crystals in lasers and acoustic surface filters according to the most recent research. We also provide an overview of future research directions for LT in the fields of acoustics, optics, and other fields. The applications of LT in 5G, 6G, SAW filters, nonlinear optical devices, and waveguides are expected to provide additional breakthroughs. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Near-stoichiometric lithium tantalate (NSLT) wafers with different Li contents were prepared by vapour transfer equilibrium (VTE) method and fabricated into surface acoustic wave filters. The temperature coefficient of frequency, insertion loss, and bandwidth of the surface acoustic wave filters were tested using a special chip test bench and a network analyzer. The results show that the temperature coefficient of frequency shows a trend of first decreasing and then increasing with the increase in Li content, and the temperature stability of the surface acoustic wave filters is best when the Li content is 49.75%. It is also found that the surface acoustic wave filter fabricated from NSLT wafers has 21.18% lower temperature coefficient of frequency, 7.3% lower insertion loss, and 2.8% lower bandwidth than those fabricated from congruent lithium tantalate wafers. Therefore, NSLT crystals are more suitable for applications in acoustic devices, providing a new idea for performance enhancement of 5G communication devices.

Raman spectra have been excited by the radiation of lasers generatingon in the visible (532 nm) and near-IR (785 nm) ranges in a LiTaO3:Cr3+ (0.005 wt%) crystal. The obtained spectra were compared. Recorded Raman spectra contained bands in the range of <900 cm−1 (first order) up to 2000 cm−1 (second order). The Raman spectra of the second order, excited by near-IR laser radiation, were located against the background of a wide, luminescent halo. The frequency of a single low-intensity band exceeded the exact frequency of an overtone corresponding to the completely symmetric fundamental 4A1(z)LO mode. The attribution of other second-order bands with higher frequencies remains unclear. [ABSTRACT FROM AUTHOR]

Recently, it was established that the X-ray generation intensity increases in a certain range of temperature variation rates (6–8°C/min) of lithium tantalate single crystal (LiTaO3). In this work, the pyroelectric current generation is studied as a function of the temperature variation rate. Four stages of the pyroelectric current generation dynamics are determined. In the same rate range (6–8°C/min), an anomalously long stage of current saturation is observed, which is most likely the cause of the observed effect of an increase in the X-ray intensity. The observed anomaly is described, as well as systematic features in the pyroelectric current dynamics with varying the pyroelectric material temperature with a constant rate. [ABSTRACT FROM AUTHOR]

This paper presents a comparative study of three types of surface acoustic waves sensors used for particulate matter detection along with a theoretical study tackling the possibility to switch to innovative materials called Piezoelectric-on-Insulator. These sensors are placed in a cascade impactor as impaction plates. Monitoring their phase variation allows us to measure the quantity of fine particles present in the air with high accuracy. Until now, the sensors used in our prototype are built on quartz substrate and present a sufficient sensitivity to fine particles. One major concern in our application is the fouling of the sensor's surface with particles upon long periods of exposure. This shaped our drive to develop a self-cleaning sensor relying on other substrates with stronger electromechanical coupling coefficient (k2) [1]. Hence, the aim of this study is to demonstrate the possibility of using strongly coupled modes on different piezoelectric substrates for an accurate PM detection. Among these, different POI substrates are considered to assess their physical and acoustic properties, especially in terms of k2 and thermal stability, for further optimization enabling their exploitation in the self-cleaning system that is being developed. [ABSTRACT FROM AUTHOR]

This article discusses the main issues of designing filters based on surface acoustic waves. A type of band-pass filter based on longitudinal resonant modes is presented. The features of the calculation based on two approaches are considered: the coupled mode model and the finite element method. Practical recommendations are proposed for reducing the time of filter calculation in numerical simulation. The results of calculating and measuring the transmission coefficient of a filter on a leaky surface acoustic waves on a 36 YX-cut lithium tantalate substrate are presented and compared. The main aspects and directions in which the considered modeling methods can be compared are highlighted and analyzed. It is shown that the use of different modeling approaches increases the development efficiency, and fast analytical models are required for the synthesis and optimization of filter parameters.

Femto-/nanosecond pulse-induced, red and near-infrared absorption is studied in $\text{LiNb}_{1-x}\text{Ta}_x\text{O}_3$ ( $0\unicode{x2A7D} x \unicode{x2A7D}1$ , LNT) solid solutions with the aim of studying transient optical nonlinearities associated with the formation, transport and recombination of optically generated small bound electron polarons with strong coupling to the lattice. As a result, a pronounced, long-lived transient absorption is uncovered for LNT which exceeds lifetimes and starting amplitudes of $\text{LiNbO}_3$ (LN) and $\text{LiTaO}_3$ (LT) by a factor of up to 100 and 10, respectively. The transients reveal a stretched-exponential decay behavior and a thermally activated process which provide strong evidence for an underlying hopping transport mechanism of small bound polarons. All findings are discussed in comparison to the model systems LN and LT within the framework of appropriate band models and optical generation of polarons via two-photon excitation. To explain the significant differences, the simultaneous presence of $\text{Nb}_\text{Li}^{5+}$ , $\text{Ta}_\text{Li}^{5+}$ antisites, and $\text{Ta}_\text{V}^{5+}$ interstitial defects, i.e. a mixture of the intrinsic defects widely established for LN and LT, is assumed for LNT.

We studied terahertz (THz) optical and dielectric properties of stoichiometric lithium tantalate (sLT) from room down to liquid nitrogen temperature in the range of 0.15–1.8 THz using terahertz time-domain spectroscopy. Two-oscillator Lorentz models were fitted well to the crystal properties for both ordinary and extraordinary waves. We also studied changes in sLT ultraviolet (UV) absorption from room to liquid nitrogen temperature. The measurements showed a significant drop in absorption in both the THz and UV ranges with cooling. According to these results cooling should increase lithium tantalate potential in optical-to-terahertz conversion of high-power 800-nm radiation. The measured properties can be used in designing nonlinear optical conversion schemes and devices based on sLT. [ABSTRACT FROM AUTHOR]

A theoretical review of the linear electro-optic effect using the optical indicatrix method is proposed. Various configurations of the linear electro-optic effect are considered, and the optimal configuration for creating an electro-optic modulator is selected. A description of the electro-optic modulator is presented. Using lithium tantalate as an example, the linear electro-optic effect of the chosen configuration is discussed, and the parameters of the crystal changed under the influence of the field are calculated. The structure that allows temperature compensation of the lithium tantalate–based electro-optic modulator is considered, and the corresponding analytical expressions for the phase difference and half-wave (control) voltage are given. The effect of low temperatures on the lithium tantalate crystal is considered, and the corresponding calculations for the half-wave voltage at extremely low temperatures are conducted. Conclusions about the feasibility of lithium tantalate–based electro-optic modulators at extremely low temperatures in emergency operation are made. [ABSTRACT FROM AUTHOR]

Photonic manipulation of large-capacity data with the advantages of high speed and low power consumption is a promising solution for explosive growth demands in the era of post-Moore. A well-developed lithium-niobate-on-insulator (LNOI) platform has been widely explored for high-performance electro-optic (EO) modulators to bridge electrical and optical signals. However, the photonic waveguides on the x-cut LNOI platform suffer serious polarization-mode conversion/coupling issues because of strong birefringence, making it hard to realize large-scale integration. Here, low-birefringence photonic integrated circuits (PICs) based on lithium-tantalate-on-insulator (LTOI) are proposed and demonstrated, which enables high-performance passive photonic devices as well as EO modulators, showing great potential for large-scale photonic chips. Analysis of mode conversion and evolution behaviors with both low- and high-birefringence shows undesired mode hybridizations can be effectively suppressed. A simple and universal fabrication process is developed and various representative passive photonic devices are demonstrated with impressive performances. Finally, a wavelength-division-multiplexed optical transmitter is developed with a data rate of 1.6 Tbps by monolithically integrating 8 EO modulators and an 8-channel arrayed waveguide grating. Therefore, the demonstrated low-birefringence LTOI platform shows strong ability in both passively and actively controlling photon behaviors on a chip, indicating great potential for ultrafast processing and communicating large-capacity data., (© 2025 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

The size uniformity and spatial dispersion of nanoparticles (NPs) formed by ion implantation must be further improved due to the characteristics of the ion implantation method. Therefore, specific swift heavy ion irradiation and thermal annealing are combined in this work to regulate the size and spatial distributions of embedded Au NPs formed within LiTaO3 crystals. Experimental results show that small NPs migrate to deeper depths induced by 656 MeV Xe35+ ion irradiation. During thermal annealing, the growth of large Au NPs is limited due to the reductions in the number of small Au NPs, and the migrated Au NPs aggregate at deeper depths, resulting in a more uniform size distribution and an increased spatial distribution of Au NPs. The present work presents a novel method to modify the size and spatial distributions of embedded NPs. [ABSTRACT FROM AUTHOR]

Color is an important property of lithium disilicate (LD) glass–ceramics for a variety of applications. For example, the color of dental glass–ceramics needs to be tuned to match the color of natural teeth. The present study examines the optical properties of LD glass–ceramics containing lithium tantalate as a secondary phase via ultraviolet–visible spectroscopy. A large data set is analyzed to investigate the relationship between heat treatments and optical properties, specifically the L*a*b* color coordinates. The color coordinates are dependent on the heat treatment following previously acquired phase data. The data are used to train a two‐step machine learning model to predict what heat treatment is needed to obtain a given set of color coordinates. [ABSTRACT FROM AUTHOR]

The Raman spectra of a lithium tantalate crystal doubly doped with chromium and neodymium LiTaO3:Cr(0.2):Nd(0.45 wt%) have been studied in this paper. Raman spectra of the first and second orders have been found to be located against the background of a luminescent halo with a maximum at ≈1250 cm−1. Several Raman bands have been detected in the frequency range of 900–2000 cm−1. Their frequencies were 940, 1034, 1113, 1171, 1250, 1343, 1428, 1491, 1582, 1735, 1838, and 1925 cm−1. These bands correspond to overtone processes. We have determined that the frequencies of 1838 and 1925 cm−1 bands are significantly higher than the exact value of the overtone frequency corresponding to the fundamental mode 4A1(z)LO (864 cm−1). [ABSTRACT FROM AUTHOR]

Lithium tantalate (LiTaO3, or LT) crystal is widely used in optical applications, infrared detection, and acoustic surface wave devices because of its excellent piezoelectric, pyroelectric, and nonlinear optical properties. In this paper, we discuss the defect structure of LT; the preparation method for LT; the influence of doping on LT; and LT’s application in optical, acoustic, and electrical devices. We mainly analyzed the structure and physical properties of LT crystal, the preparation of LT crystal and LT thin films, the periodic polarization of LT crystal, the reduction of LT wafers, and the application potential of LT crystals in lasers and acoustic surface filters according to the most recent research. We also provide an overview of future research directions for LT in the fields of acoustics, optics, and other fields. The applications of LT in 5G, 6G, SAW filters, nonlinear optical devices, and waveguides are expected to provide additional breakthroughs.

This paper discusses the applicability of double busbar design to surface acoustic wave (SAW) devices employing low-cut lithium tantalate (LT) with a multi-layered structure. This design offers good energy confinement, scattering loss suppression and transverse mode suppression for a wide frequency range. In addition, the effectiveness of manipulating the slowness curve shape for transverse mode suppression is demonstrated. First, three different lateral edge designs are applied to the layered SAW configuration on low-cut LT, and their performances are compared using the periodic three-dimensional finite-element method powered by the hierarchical cascading technique. Then, the discussion is extended to the influence of the SAW slowness shape to the transverse mode suppression. [ABSTRACT FROM AUTHOR]

An infrared sensor with Au/SiO2/Au metamaterial perfect absorber (MPA) structure and Crystal ion slicing (CIS) fabricated LiTaO3 single crystal film to realize wavelength-selective function was proposed and fabricated in this paper. The Au/SiO2/Au multilayer MPA exhibited outstanding wavelength selectivity at $4.04\mu \text{m}$ with a maximum absorbance of 98% and the spectral voltage response of sensor highly agreed with it. Meanwhile, the sensor performed stable angle independency with radiation incident angle from 0° to 50°. After integration, this sensor showed maximum voltage responsivity of ${1.7} \times {10}^{{4}}\text{V}$ /W, maximum detectivity of ${1.7} \times {10}^{{8}}$ cmHz1/2/W, and 5.8ms response time. These results demonstrate the promising application prospect of high specific and fast response pyroelectric infrared sensor achieved by integrating MPA with LiTaO3 thin film. [ABSTRACT FROM AUTHOR]

This paper presents a short review of the microwave acoustics area, where exciting material innovations and performance advancements have been made in the past decade. The ever-growing demand for more sophisticated passive signal processing functions on-chip has fueled these developments. As a result, microwave acoustic devices have maintained performance leadership in mobile applications. By evaluating three fundamental parameters, namely electromechanical coupling (k2), quality factors, and frequency scalability, of microwave acoustics, this paper aims to, extensively but not exhaustively, capture the rationales behind approaches achieving higher performance microsystems. Outlooks for different material systems and addressing their underlying challenges are also offered in hopes of establishing a balanced roadmap for future microwave acoustics development.

Counting on its remarkable electro‐optical, pyroelectric, and piezoelectric properties, lithium tantalate (LT) has been applied in optical modulator, infrared sensors, and other devices. LT thin film with different crystal orientation is necessary for different applications and crystal ion slicing technology has fabricated single‐crystalline LT film successfully. During crystal ion slicing, the relation of defects and implantation ions is crucial for film fabrication. Comprehensive and nondestructive method is a good choice to figure out the relation and have a guide in crafting process. Z‐cut LT crystal wafers implanted with different H‐ion fluences are investigated in this research. Optical spectra, Raman spectra, and X‐ray diffraction spectra are measured, corresponding to the thermal annealing exfoliation experiment, to analyze the interactive of implantation, defects, and exfoliation. Based on the results and analysis, oxygen vacancies and H‐ion interstitials affect the crystal lattice and behave as strain increase in lattice. Strain increase contributes to the activation energy Ea decrease and once the Ea decreases to a limit value, exfoliation is able to happen. Depending on this analysis method, a direction to optimize exfoliation of H‐ion implanted LT has been found. Moreover, this method can also be used by optimizing crystal ion slicing technology in other materials. [ABSTRACT FROM AUTHOR]

Abstract The electrical conductivity of lithium tantalate thin film on the silicon substrate was studied. The film structure was prepared by RF magnetron sputtering. In general, the current-voltage characteristics were asymmetric and similar to that of a diode. The current-voltage characteristics had several sections associated with various transport mechanisms of current carriers. The main conductivity mechanism was related to the space-charge-limited current. The current-voltage characteristics showed that there was a mismatch between the forward and backward runs. One of the reasons for such behavior is a space charge accumulation due to charge carriers which were injected from the electrode and did not relax.

Raman spectra have been excited by the radiation of lasers generatingon in the visible (532 nm) and near-IR (785 nm) ranges in a LiTaO3:Cr3+ (0.005 wt%) crystal. The obtained spectra were compared. Recorded Raman spectra contained bands in the range of −1 (first order) up to 2000 cm−1 (second order). The Raman spectra of the second order, excited by near-IR laser radiation, were located against the background of a wide, luminescent halo. The frequency of a single low-intensity band exceeded the exact frequency of an overtone corresponding to the completely symmetric fundamental 4A1(z)LO mode. The attribution of other second-order bands with higher frequencies remains unclear.

Differential phase contrast scanning transmission electron microscopy (DPC STEM) is a powerful technique for directly visualizing electromagnetic fields inside materials at high spatial resolution. Electric field observation within ferroelectric materials is potentially possible by DPC STEM, but concomitant diffraction contrast hinders the quantitative electric field evaluation. Diffraction contrast is basically caused by the diffraction-condition variation inside a field of view, but in the case of ferroelectric materials, the diffraction conditions can also change with respect to the polarization orientations. To quantitatively observe electric field distribution inside ferroelectric domains, the formation mechanism of diffraction contrast should be clarified in detail. In this study, we systematically simulated diffraction contrast of ferroelectric domains in DPC STEM images based on the dynamical diffraction theory, and clarify the issues for quantitatively observing electric fields inside ferroelectric domains. Furthermore, we conducted experimental DPC STEM observations for a ferroelectric material to confirm the influence of diffraction contrast predicted by the simulations., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Japanese Society of Microscopy.)

Formation of the original dendrite snowflake-shape domains during fast cooling after heating above phase transition temperature by pulse laser irradiation was revealed in congruent lithium tantalate crystals. The effect was attributed to polarization reversal under the action of spatially nonuniform pyroelectric field. Two stages of the domain shape evolution at the surface were separated: (1) growth of circular domains by sideways motion of the domain walls and (2) backswitching leading to formation of the snowflake domains. The simulated spatial distribution of the pyroelectric field in regular two-dimensional structure was used for an explanation of the obtained results. The backswitching process in the surface layer has been attributed to change of the sign of the pyroelectric field at the domain wall. The snowflake domain shape is caused by the formation of isolated nanodomain fingers and hampering of their merging. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, we present a new vacancy model which proves that both lithium and tantalate (niobium) vacancies can coexist in the lattice structure of lithium tantalate and lithium niobate. Using the theoretical approach to the defect structure analysis, which is developed by Safaryan, a comparison between three defect models (tantalate/niobium vacancies, lithium vacancies, and mixed vacancies) has been proposed. The calculated values of the Curie temperature for different compositions of nonstoichiometric lithium tantalate and lithium niobite show that the mixed vacancy model can effectively describe the defect structure in nonstoichiometric lithium tantalate and lithium niobate. Also, it can reveal good correspondence with experimental results. [ABSTRACT FROM AUTHOR]

Lithium disilicate glass‐ceramics were discovered in the 1950s, and the evolution of the main target phase of these materials is well known. However, the lithium disilicate system is still an area of active research, especially when a secondary phase is introduced since the phase evolution of secondary phases is not currently understood. The present study examines the main target phases, as well as a secondary phase of lithium tantalate, via X‐ray diffraction. A large data set is obtained to investigate the evolution of all phases. It is found that the nucleation of the precursor lithium metasilicate phase is coupled to both the nucleation of the primary target phase, lithium disilicate, and the nucleation of lithium tantalate. A reaction equation describing this relationship is proposed. [ABSTRACT FROM AUTHOR]

Lithium niobate (LiNbO3) and lithium tantalate (LiTaO3) are among the most important and most widely used materials of coherent and nonlinear optics, as well as acoustics. The strict requirements on the uniformity and reproducibility of characteristics have become the base of the industrial technology for the production of high-quality crystals, mastered by many enterprises around the world. However, using LiNbO3 and LiTaO3 is not limited to the areas listed above due to their pronounced piezo and ferroelectric properties. One of the promising areas of using crystals is the creation, based on them, of electromechanical converters for precision sensors and actuators. At the same time, the high thermal stability of the piezoelectric and mechanical properties, as well as the absence of hysteresis and creep, make it possible to create electromechanical transducers capable of operating in a wide temperature range unattainable for ferroelectric materials commonly used for these purposes. The main advantage of LiNbO3 and LiTaO3 over other monocrystalline piezoelectrics is the possibility of a directed effect on the characteristics of devices by controlling the ferroelectric domain structure of crystals. One of the most striking examples of the use of domain engineering to create electromechanical converters based on crystals is the formation in them of the so-called bidomain structure: two macroscopic domains located in one crystal plate, having oppositely directed vectors of spontaneous polarization separated by a charged domain wall. Highly coercive switching fields make the inverse domains stable up to the Curie temperature (about 1140°C for LiNbO3 and 600°C for LiTaO3). This review discusses the main achievements in the field of the formation of a bidomain structure and near-surface inverse domains in LiNbO3 and LiTaO3 crystals. Methods for visualizing the domain structure in crystals and nondestructive methods for monitoring the position of the interdomain boundary are presented. A comparative analysis of the methods for the formation of inverse domains in crystals is carried out, and the regularities and technological methods of controlling the domain structure are discussed. The main physical models proposed in the literature to explain the effect of the formation of inverse domains are presented, and their strengths and weaknesses are considered. Methods for choosing a crystallographic cut to create devices that use bidomain crystals (BCs) are briefly listed. Examples of implementation of devices based on BCs are given: actuators, sensors, acoustic transducers, and waste energy collection systems. [ABSTRACT FROM AUTHOR]

This paper presents the results of ultrasonic measurements in trigonal LiTaO3 crystals. The samples of direct section with faces perpendicular to the main crystallographic axes and X/45 sections of LiTaO3 crystals were manufactured for experimental studies. The velocities of longitudinal and transverse acoustic waves along the three principal crystallographic axes and two additional axes in theYZ plane in trigonal crystals of point group 3m LiTaO3 crystals were measured using the pulse-echo overlap method. In the piezoelectric crystals, elastic and electrical properties are related and the propagation of an acoustic wave is accompanied by the appearance of electric fields, which must be taken into account in the calculations. The relations for the complete determination of all components of the matrices of elastic stiffness and piezoelectric coefficients based on all necessary acoustic wave velocities measured were derived from the Christoffel equation for the piezoelectric crystals. Using the obtained ratios, all components of the tensors of piezoelectric coefficients, elastic stiffness constants, as well as all elastic compliances of LiTaO3 crystals are calculated. The obtained results are consistent with the literature data and will be used in further measurements and calculation of the spatial anisotropy of induced (electro-, piezo- and acousto-optical) effects on the same crystal samples in order to select the most effective geometry of their possible practical use. [ABSTRACT FROM AUTHOR]

The microstructure of ceramic lithium tantalite LiTaO3, obtained on the basis of finely dispersed microcrystalline monophasic powder, was studied by the probe microscopy. A comparative study of the dispersion of the complex impedance Z*(ω) of LiTaO3 and a crystalline sample of a non-polar X-orientation slice, grown by the Czochralski method, was carried out. Using measured Z and φ values, the real and imaginary components of the complex dielectric constant and impedance (admittance) are determined.

The Raman spectra of a lithium tantalate crystal doubly doped with chromium and neodymium LiTaO3:Cr(0.2):Nd(0.45 wt%) have been studied in this paper. Raman spectra of the first and second orders have been found to be located against the background of a luminescent halo with a maximum at ≈1250 cm−1. Several Raman bands have been detected in the frequency range of 900–2000 cm−1. Their frequencies were 940, 1034, 1113, 1171, 1250, 1343, 1428, 1491, 1582, 1735, 1838, and 1925 cm−1. These bands correspond to overtone processes. We have determined that the frequencies of 1838 and 1925 cm−1 bands are significantly higher than the exact value of the overtone frequency corresponding to the fundamental mode 4A1(z)LO (864 cm−1).

High energy heavy ion irradiation has been performed in LiTaO 3 in a broad set of experimental conditions to study the synergistic effects in the damage generation between the nuclear and the electronic energy loss mechanisms. Optical waveguides have been fabricated in LiTaO 3 , using 20–25 MeV F and 40 MeV Si ions, and their refractive index profiles were used as a very accurate method for the in-depth damage profile determination and its correlation with the energy loss curves. In-situ optical reflectance of low energy irradiations (500 keV F and 300 keV Si ions) has been performed to estimate the nuclear damage kinetics of the buried regions of the high energy irradiations that are not optically accessible with the optical waveguide characterization in the fluence regime when the electronic damage is intense. The angle of incidence has been varied to enhance the damage and further ascertain the existence of a synergistic mechanism. [ABSTRACT FROM AUTHOR]

Crystal ion slicing (CIS) technology has been widely applied to fabricate single-crystalline quality thin film, although the ion implantation process can cause lattice strain and electric properties changes in the fabricated film. In this paper, CIS-fabricated Z-cut LiTaO3 (LT) thin films were annealed under different temperatures and times by rapid thermal annealing (RTA). The effects of annealing parameters on microstructure and dielectric properties of LT films were studied. It is found that the lattice strain can be partially released by RTA according to the XRD diffraction peak shift and this lattice release also has an influence on the permittivity and dielectric loss. Additionally, anomalous recrystallization behavior has been observed in the samples annealed at higher temperature or longer time according to the abnormal grain growth revealed by AFM. Besides, unusual permittivity and dielectric loss increase in sample annealed at 600℃ was measured and it may result from the abnormal grain growth. In summary, it is indicated by the results that RTA is an effective way to release lattice strain and it can impact electric properties of CIS-fabricated LT thin film. [ABSTRACT FROM AUTHOR]