Large Electromechanical Coupling Factor Research Articles

Attempt for excellent piezoelectric performance in Sb-free (K,Na)NbO3-based ceramics

Piezoelectric temperature stability is often a very important item for piezoelectric materials when putting them into practical applications like filters and ultrasonic transducers. Phase transitions of (K,Na)NbO3-based compositions that contain neither toxic Pb nor Sb elements were tailored to simultaneously acquire enhanced piezoelectric properties and good piezoelectric temperature stability in this study. Specifically, dense 0.94(K0.48Na0.52)NbO3-0.03BaZrO3-0.01BaSnO3-0.02(Bi0.5Na0.5)ZrO3 ceramic and its further compositionally modified one by 1 wt% MnO2 were prepared. Both of these two ceramics display quite weak piezoelectric temperature dependence in the usage temperature range between −30 °C–100 °C, but the one modified by MnO2 has the significantly improved piezoelectric properties with a high piezoelectric coefficient d33 of 310 pC/N and large electromechanical coupling factors kp and k33 of 0.57 and 0.73 at room temperature. The obtained excellent piezoelectric performance is considered to be associated closely with the stable piezoelectric characteristic of the orthorhombic phase and the diffused rhombohedral-orthorhombic and orthorhombic-tetragonal phase transitions.

SAW velocity reduction and spurious modes suppression on the layer structure

This paper discusses the use of the layered structure for the SAW velocity reduction. First, it is shown that the insertion of SiO2 is crucial between the piezoelectric layer and the base substrate to keep a large electromechanical coupling factor even when the SAW velocity is reduced. It is also shown that the use of a high-velocity substrate such as Si is also crucial for bringing spurious resonances much higher than the main resonance. The impact of Si orientation is also discussed. Next, suppression of transverse mode resonances and lateral leakage is studied. It is shown that the double busbar structure offers Q enhancement through good lateral energy confinement, and its combination with the piston design also gives good transverse mode suppression. Furthermore, discussions are extended to a strong spurious resonance that appears near the anti-resonance.

Simulation and Optimization of Surface Acoustic Wave Devices With High Electromechanical Coupling Factor and Zero Temperature Coupling Coefficient by Pattern Piezoelectric Layer

Recently, a more popular patterned surface acoustic wave (SAW) device with better performance was proposed. This structure has a large electromechanical coupling factor. To make surface acoustic wave devices easy to be applied to integrated circuit technology, a multilayer structure based on patterned Al/ZnO/Si is designed by using finite element method (FEM). Firstly, dependence of ZnO piezoelectric material on electromechanical coupling factor is studied systematically. The results show that Al/ZnO/Si structure excites Rayleigh mode and Sezawa mode with high electromechanical coupling factor. The patterning of piezoelectric materials could be achieved by etching. The electromechanical coupling factor of Rayleigh mode is as high as 7.98%, and the electromechanical coupling factor of Sezawa mode is up to 9.68%. As we all know, temperature will affect the characteristics of SAW devices. Therefore, the temperature characteristics based on this structure are systematically studied. To achieve zero temperature coupling coefficient, SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is used as an intercalation layer for temperature compensation. The structure of Rayleigh mode and Sezawa mode with the thinner SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> layer is easier to achieve zero temperature coupling coefficient than that of conventional structure. Meanwhile, the electromechanical coupling factor of Sezawa mode based on patterned Al/ZnO/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Si structure does not change significantly with the increase of SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> thickness, with the maximum value of 10.78%, and the minimum value of 10.62%, which is 1.1% larger than that of structure without SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> .

Ultrahigh Performance Piezoelectric Energy Harvester Using Lead-Free Piezoceramics with Large Electromechanical Coupling Factor

The output power of piezoelectric energy harvester (PEH) at the resonance frequency is dependent on the electromechanical coupling factor ( k p ) of the piezoceramic, which is proportional to d 33 / ε T 33 1 / 2 , where d 33 and ε T 33 are the piezoelectric change and dielectric constants, respectively. Therefore, the piezoceramic for the PEH should have a large d 33 and a small ε T 33 . [001]-texturing can be used for developing piezoceramics for PEH because it generally increases d 33 without increasing ε T 33 . The 0.96(K0.5Na0.5)(N1-zSz)O3-0.03(Bi0.5Ag0.5)ZrO3-0.01SrZrO3 [KN(N1-zSz)-BAZ-SZ] piezoceramics were textured along the [001] orientation, and the piezoceramic ( z = 0.01 ) showed a large k p of 0.77, which is the largest k p for KNN-related piezoceramics reported in the literature. The cantilever-type PEH manufactured using the KN(N0.99S0.01)-BAZ-SZ piezoceramic exhibited a large output power density of 7.86 mW/cm3 at resonance frequency because of its large k p . To date, this is the largest power density for PEHs manufactured utilizing lead-free piezoceramics. Hence, the [001]-textured KN(N0.99S0.01)-BAZ-SZ piezoceramic is an excellent candidate for PEH, and [001]-texturing is a very efficient method for developing piezoceramics for PEH.

High quality crystal growth and characterization of ferroelectric Ba0.77Ca0.23TiO3 single crystal

[Formula: see text][Formula: see text]TiO3 (BCT) single crystal has been widely studied as a promising lead-free ferroelectric material. In this work, high-quality BCT crystal was successfully grown by the Czochralski (CZ) method. The as-grown crystal is crack-free and shows black coloration. It possesses a high dielectric stability over a wide temperature range, while the dielectric loss is rather small below 90[Formula: see text]C. Furthermore, it possesses excellent ferroelectric properties with residual polarization strength ([Formula: see text]) and coercive field ([Formula: see text][Formula: see text]) of 17.93 [Formula: see text]C/cm2 and 8.47 kV/cm, respectively. Besides, BCT crystal shows large electromechanical coupling factors, with [Formula: see text][Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] of 0.535, 0.254, 0.714 and 0.721, respectively. The piezoelectric coefficients [Formula: see text], [Formula: see text] and [Formula: see text] are measured to be − 36.5, 130 and 246 pC/N, respectively.

A near spurious-free 6 GHz LLSAW resonator with large electromechanical coupling on X-cut LiNbO3/SiC bilayer substrate

The fast development of the fifth-generation (5G) wireless systems and substantial growth of data usage have imposed stringent requirements for high-frequency and wideband radio frequency devices. Here, it is reported on a longitudinal leaky surface acoustic wave (LLSAW) mode acoustic resonator with a large electromechanical coupling factor (kt2), high operating frequency, and efficient spurious suppression. Through systematical finite element method simulations, available design spaces such as supporting substrate, propagation angle, and lithium niobate (LN) thickness have been fully investigated with the aim of stimulating the intended LLSAW and suppressing spurious modes concurrently. Optimization results reveal that the LLSAW mode wave propagating in X-35°Y LN/SiC piezoelectric-on-insulator (POI) bilayer structure possesses a large kt2 without significant interference from other spurious modes. To verify the theoretical analyses, LLSAW resonators were fabricated and exhibited a near spurious-free response with the operating frequency over 6 GHz, and kt2 as large as 22.7%. This work demonstrates a high-performance LLSAW resonator on the POI platform with a simple prototype as well as potentially providing a high-frequency filtering solution for 5G applications in the 6-GHz spectrum.

Inch-Size Molecular Ferroelectric Crystal with a Large Electromechanical Coupling Factor on Par with Barium Titanate.

Molecular ferroelectrics with large piezoelectric responses have long been sought for their advantages of light weight, mechanical flexibility, and easy preparation, in contrast to the widely used inorganic counterparts. Representatively, a molecular ferroelectric crystal [Me3NCH2Cl]CdCl3 (TMCM-CdCl3) has been found to show a large piezoelectric coefficient d33 of 220 pC/N exceeding that of BaTiO3 (You et al. Science2017, 357, 306-309). However, although the d33 of molecular ferroelectrics has achieved great progress, their electromechanical coupling factor k33, which is essential for various piezoelectric applications, including ultrasonic transducers and actuators, was rarely explored and is far below the level of inorganic ferroelectrics. The major reason for this situation is the great challenge of growing large-size crystals which is a key limiting factor for measuring k33. Here, we grew inch-size crystals of organic-inorganic perovskite ferroelectric TMCM-CdCl3 with a high d33 (383 pC/N) for investigating its piezoelectric responses including the k33 (0.483) by the resonance method. Such high k33 (0.483) is much larger than those of other molecular ferroelectrics and competitive with that of BaTiO3 (0.5). In addition, TMCM-CdCl3 has a low elastic modulus of 13.03 GPa, an order of magnitude lower than that of BaTiO3. This finding sheds light on the exploration of large electromechanical coupling factors in molecular ferroelectrics for potential applications in flexible and portable piezoelectric devices.

Preparation and simulation of lead free NBBT/epoxy 1–3 piezoelectric composites for high frequency medical ultrasound

This paper presents the modeling and fabrication of the (1-x)Na0.5Bi0.5TiO3-xBaTiO3 single crystal/epoxy 1–3 piezoelectric composite (NBBT 1–3 composite) with large electromechanical coupling factor (kt) for high frequency ultrasonic transducers. The NBBT 1–3 composite has been modeled by performing the finite element method using the COMSOL Multiphysics software. The parameters related to NBBT crystal are refined in the modeling process and the simulation results agree well with that of the experiment. The composite has been fabricated by the dice-and-fill method with a pitch of 12 μm. The measured resonance frequency, antiresonance frequency and electromechanical coupling factor (kt) with the values of 31.88 MHz, 43.16 MHz and 71.06% are obtained, respectively. The excellent performance of NBBT/epoxy 1–3 piezoelectric composite is comparable to that of lead-based Pb(Mg1/3Nb2/3)O3–PbTiO3/epoxy 1–3 piezoelectric composites. The excellent performance and the lead-free advantages make the NBBT/epoxy 1–3 piezoelectric composites quite attractive in high frequency medical ultrasound applications especially within the human body like intravascular ultrasound imaging (IVUS).

Piezoelectric acoustic wave characteristics of Pb(In0.5Nb0.5)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal substrate: A comparative study with and without SiO2 overlay

This paper investigates the excitation and propagation characteristics of a piezoelectric acoustic wave propagating in a rotated Y-cut X-propagating Pb(In0.5Nb0.5)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) relaxor-based ferroelectric single crystal substrate. Numerical simulations were performed to evaluate the acoustic wave properties by FEM software COMSOL. For comparison, two types of structures are taken into consideration: one is the traditional metal electrode/YX-PIN-PMN-PT and the other is silicon dioxide (SiO2) overlay/metal electrode/YX-PIN-PMN-PT substrate. It is shown that shear-horizontal (SH)-type piezoelectric boundary acoustic waves (PBAW) exist in the SiO2 overlay/metal electrode/YX-PIN-PMN-PT substrate and offer a fairly large electromechanical coupling factor K2 of 30%. Compared to a surface acoustic wave excited in the metal electrode/YX-PIN-PMN-PT substrate, enlarged phase velocity and significantly improved quality factor (∼3500) are simultaneously obtained for SH-type PBAW, which are promising for electromechanical transducer applications with high performance.

Structure with thin SiOx/SiNx bilayer and Al electrodes for high-frequency, large-coupling, and low-cost surface acoustic wave devices

With the development of fifth-generation wireless systems, the Internet of Things, and health services, surface acoustic wave (SAW)-based filters and sensors have attracted considerable interest. This study presents a new structure for high-frequency, large-coupling, and low-cost SAW devices that helps implement high-frequency and wideband filters and enhances the sensitivity of sensors. The structure is based on 15°Y-X LiNbO3, thin SiOx/SiNx bilayer overlay, and Al electrodes. Furthermore, a low-cost fabrication process for SAW devices based on this structure was designed. Simulation and experimental results show that the bilayer substantially weakens the leaky nature of shear-horizontal-type SAWs with a phase velocity higher than that of a slow-shear bulk wave in LiNbO3. Thus, the limitation related to the velocity of 4029 m/s was overcome, and the phase velocity reached approximately 4500 m/s, which means an increase of 50% compared with that of conventional Cu/15°Y-X LiNbO3 devices. Consequently, the frequency dramatically increases, and the quality of the SAW response is ensured. Simultaneously, a large electromechanical coupling factor close to 20% can be achieved, which is still suitable for wideband filters and sensors with high energy transduction coefficients. This new structure is expected to become a major candidate for SAW devices in the future.

Thin-film lithium niobate-on-insulator (LNOI) shear horizontal surface acoustic wave resonators

This work investigates the design methodology to obtain large electromechanical coupling factor () and high quality factor (Q) of shear-horizontal surface acoustic wave (SH-SAW) resonators based on the thin-film lithium niobate-on-insulator (LNOI) technology. The guided SH wave can be excited through interdigital transducers and propagate at the very surface of the material stackings. Such a guided SH wave in LN/SiO2 double layer structure is expected to offer high by confining the elastic strain energy in the piezoelectric thin film. To capture the optimum design window for high-performance LNOI SH-SAW devices, the impact of electrode material and its thickness on the dispersive characteristics are intensively investigated by finite element method (FEM). In this study, various one-port resonators with wavelengths from 2.8 μm to 8 μm were fabricated on a LNOI wafer with LN and SiO2 thickness of 0.7 and 2 μm, respectively. The 100 nm thick gold film was chosen as the electrode of the devices, which demonstrate a similar dispersive behavior to the FEM simulation with small discrepancy. Among the measurement results over several tested samples, a high- of 25.5% and Q of 960 was recorded at a resonance frequency of 581 MHz (FOM = = 245), revealing great potential for the application of wide-band frequency selection in telecommunications.

Squared figures of merit and electromechanical coupling factors of a novel lead-free 1–3–0 composite for sensor and energy-harvesting applications

Piezoelectric sensitivity and energy-harvesting parameters are studied for a novel lead-free 1–3–0 composite where domain-engineered single-crystal rods are surrounded by a polymer matrix containing two types of air pores. Correlation between some effective parameters, concerned with the high piezoelectric sensitivity of the composite, and the elastic properties of its porous matrix is first stated. Diagrams are first built to show volume-fraction ranges wherein conditions for large squared figures of merit (Q33*)2=d33* g33*≥200⋅10−12 Pa−1 (longitudinal) and (Qh*)2=dh* gh*≥50⋅10−12 Pa−1 (hydrostatic) hold, where d33*, dh*. g33*, and gh* are piezoelectric coefficients of the composite. The studied composite is also of interest due to its large electromechanical coupling factors kt* ≈ 0.8–0.9 (thickness) and kh* ≈ 0.5–0.6 (hydrostatic). Piezoelectric sensitivity, electromechanical coupling factors and other characteristics are compared to those of a lead-containing 1–3–0 composite and a few 1–3 composites. Correlation between the effective parameters of the 1–3–0 composite and elastic properties of its porous matrix is discussed. Replacing the parallelepiped-shaped single-crystal rods with the cylindrical rods in the 1–3–0 composite leads to minor changes in the aforementioned parameters. The performance of the studied lead-free 1–3–0 composite proves its suitability for modern piezoelectric sensors, energy-harvesting and hydroacoustic devices.

Comparison of effective parameters of lead-free 1–3-type composites based on ferroelectric single crystals

The article reports results of the comparative study on the performance of lead-free 1–3-type composites based on domain-engineered lead-free ferroelectric single crystals. Of interest are the 1–3–0 ferroelectric single crystal/porous polymer and 1–0–3 ferroelectric single crystal/piezoelectric single crystal/polymer composites with heterogeneous matrices. In the 1–3–0 composite this matrix is a polymer medium with the system of spheroidal air pores. In the 1–0–3 composite the polymer matrix contains a system of spheroidal piezoelectric single crystal inclusions, and the arrangement of these inclusions is similar to that of the pores in the matrix of the related 1–3–0 composite. Volume-fraction and aspect-ratio dependences of the piezoelectric properties, squared figure of merit and electromechanical coupling factors of the 1–3-type composites are analysed, and comparison of the effective parameters of the composites is made. The role of the composite microgeometry in forming the piezoelectric anisotropy and squared figures of merit is discussed. Due to large electromechanical coupling factors, squared figures of merit and anisotropy factors, the studied lead-free 1–3-type composites are of interest as advanced materials suitable for piezoelectric transducer, sensor and energy-harvesting applications.

Exploring the high-performance (1-x)BaTiO3-xCaZrO3 piezoceramics with multiphase coexistence (R-O-T) from internal lattice distortion and domain features

Although the multiphase coexistence has made great achievements in improving the piezoelectric properties of barium titanate-based (BT) ceramics, the problems such as internal lattice distortion and external physical mechanism at the phase boundary still remain. Here, we have studied the phase structure, atomic parameters and domain structure of (1-x)BaTiO3-xCaZrO3 (abbreviated as BT-xCZ) ceramics. By regulating the phase transition temperatures, the rhombohedral-orthorhombic-tetragonal (R-O-T) multiphase coexistence (x = 0.06) is realized at room temperature. Notably, high piezoelectric constant of d33 ∼ 445 ± 20 pC/N and large electromechanical coupling factor of kp = 55% are obtained at x = 0.06. With the doping of CaZrO3 (CZ), the lattice of ceramics is distorted, thereby increasing the ferroelectricity and piezoelectricity. Importantly, the domain structure of BT-xCZ ceramics observed by the acid etching technology further proves that the high piezoelectricity is attributed to the multiphase coexistence and reduction of the domain wall energy density.

Electromechanical properties of ternary BiFeO3−0.35BaTiO3–BiGaO3 piezoelectric ceramics

In the present work, composition dependent crystal structure, ferroelectric, piezoelectric, and temperature dependent dielectric properties of the BiGaO3-modified (1–x)(0.65Bi1.05FeO3–0.35BaTiO3) (BFBT35–xBG, where x = 0.00–0.03) lead-free ceramics were systematically investigated by solid-state reaction method, followed by water quenching process. The substitution of BG successfully diffuses into the lattice of the BFBT ceramics, without changing the pseudo-cubic structure of the samples. The scanning electron microscopy (SEM) results revealed that the average grain size was increased with BG-content in BFBT system. The BFBT–xBG ceramics showed a maximum in permittivity (ɛmax) at temperatures (Tmax) above 500 °C in the compositional range of 0.00 ≤ x ≤ 0.03. The electro-strain is measured to be 0.125% (d*33 ~ 250 pm/V) under unipolar fields (5 kV/mm) for BFBT–0.01BG ceramics. The same composition (x = 0.01), large static piezoelectric constant (d33 ~ 165 pC/N) and electromechanical coupling factor (kp ~ 25%) were obtained. The above investigated characterizations suggests that BFBT–BG material is favorable for piezoelectric and high temperature applications.

Highly temperature-stable piezoelectric properties of 0.96(K0.48Na0.52)(Nb0.96Sb0.04)O3–0.03BaZrO3–0.01(Bi0.50Na0.50)ZrO3 ceramic in common usage temperature range

Piezoelectric temperature stability is often a critical issue for the (K,Na)NbO3-based lead-free ceramics when used in some technical products like filters and ultrasonic devices. In this letter, we report the excellent piezoelectric performance of a dense 0.96(K0.48Na0.52)(Nb0.96Sb0.04)O3–0.03BaZrO3–0.01(Bi0.50Na0.50)ZrO3 ceramic, which shows high piezoelectric coefficient d33 = 300 pC/N and large electromechanical coupling factors kp = 0.56, k33 = 0.69 at room temperature and weak piezoelectric temperature dependences in the common usage temperature range between −30 °C and 100 °C. It seems that the obtained excellent piezoelectric performance associates closely with the diffused R-O phase transition and the stable piezoelectric nature of orthorhombic phase.

Anisotropy Factors and Electromechanical Coupling in Lead-Free 1-3-Type Composites.

The effective electromechanical properties and anisotropy factors of novel lead-free 1-3-type composites are studied to demonstrate their large piezoelectric anisotropy and considerable level of electromechanical coupling. The composites studied contain two single-crystal (SC) components and a polymer component. The first piezoactive component is a domain-engineered [001]-poled SC based on ferroelectric alkali niobates-tantalates, and this component is in the form of a system of long rods that are parallel to the poling axis . The second SC component is a system of spheroidal piezoelectric Li2B4O7 inclusions aligned in a continuous and relatively large polymer matrix. The SC rods are surrounded by an SC/polymer matrix, and the connectivity of the composite is 1-0-3. It is shown that the conditions , which indicates a large degree of anisotropy of the piezoelectric coefficients, and and , which indicate a large anisotropy of the electromechanical coupling factors (ECFs), can be achieved simultaneously in specific ranges of the component volume fractions and inclusion aspect ratios. Moreover, in the same volume-fraction and aspect-ratio ranges, large ECFs ( -0.9) are also achieved. In this context, the important role of the elastic properties of the continuous anisotropic matrix is discussed. The properties and anisotropy factors of the lead-free 1-3-type composites are compared to the similar parameters of conventional lead-containing piezoelectric materials, and the advantages of the composite system studied are described.

Ferroelectric, elastic, piezoelectric, and dielectric properties of Ba(Ti0.7Zr0.3)O3-x(Ba0.82Ca0.18)TiO3 Pb-free ceramics

We designed and synthesized a pseudo-binary Pb-free system, Ba(Ti0.7Zr0.3)O3-x(Ba0.82Ca0.18)TiO3, by combining a rhombohedral end (with only cubic to rhombohedral ferroelectric phase transition) and a tetragonal end (with only cubic to tetragonal ferroelectric phase transition). The established composition-temperature phase diagram is characterized by a tricritical point type morphotropic phase boundary (MPB), and the MPB composition has better ferroelectric, piezoelectric, and dielectric properties than the compositions deviating from MPB. Moreover, a full set of material constants (including elastic stiffness constants, elastic compliance constants, piezoelectric constants, dielectric constants, and electromechanical coupling factors) of the MPB composition are determined using a resonance method. The good piezoelectric performance of the MPB composition can be ascribed to the high dielectric constants, elastic softening, and large electromechanical coupling factor.

Enhanced piezoelectricity in (K, Na)NbO3-based ceramics by optimizing composition and texture process

In this study, <00l>-textured (1-x)(K0.5Na0.5)0.95Li0.05Nb0.93Sb0.07O3-xBaZrO3 [abbreviated as (1-x)KNLNS-xBZ, x = 0.01, 0.02, 0.04, 0.06, 0.08] lead-free ceramics are prepared by template grain growth (TGG) method using NaNbO3 templates. The effects of BZ content on the phase structure, microstructure, as well as electrical properties of ceramics are investigated. Large piezoelectric constant d33 (∼234 pC/N) and planar electromechanical coupling factor kp (∼38.42%) are obtained in the ceramics with x = 0.02, and high field-induced strain (d33∗ ∼ 403.5 pm/V) is also achieved in the rhombohedral-orthorhombic-tetragonal phase coexistent area due to multiphase coexistence. These results show that the introduction of BaZrO3 is a very effective way to improve the electrical properties of textured (K0.5Na0.5)0.95Li0.05Nb0.93Sb0.07O3 lead-free piezoelectric ceramics.

Loss reduction of leaky surface acoustic wave by loading with high-velocity thin film

The propagation properties of a leaky surface acoustic wave (LSAW) on rotated Y-cut X-propagating lithium niobate (YX-LN) substrates loaded with an aluminum nitride (AlN) thin film with a higher phase velocity than that of the substrate were investigated theoretically and experimentally. From the theoretical calculation, it was found that the minimum attenuation can be obtained at a certain thickness of the AlN thin film for a cut angle ranging from 0 to 60° because the cut angle giving the minimum attenuation shifts toward a smaller cut angle as the film thickness is increased. The propagation properties of an LSAW on several rotated YX-LN substrates were measured by using an interdigital transducer (IDT) pair with a wavelength λ of 8 µm, and the predicted shifts of the minimum attenuation toward a smaller cut angle were demonstrated experimentally. For 0° and 10°YX-LN samples, the measured insertion loss and propagation loss were markedly reduced by loading with the AlN thin film. A larger electromechanical coupling factor (16.9%) than that at the cut angle giving zero attenuation without a film and a propagation loss less of 0.02 dB/λ were obtained simultaneously at a film thickness of 0.125 λ for the 10°YX-LN sample.