Xin Yin

Elastic, dielectric, and piezoelectric properties of BaTeMo2O9 single crystal

BaTeMo2O9 is a noncentrosymmetric single crystal for nonlinear optical applications. In this letter, we report complete set of elastic, dielectric, and piezoelectric constants of BaTeMo2O9 single crystal determined by resonance technique and impedance analysis, the relative constants have been obtained and discussed. Our results show that BaTeMo2O9 crystal has excellent piezoelectric property (d34=30.25pC∕N, s44=36.46pm2∕N) and could be a promising candidate for piezoelectric applications.

Electro-optic properties of BaTeMo2O9 single crystal

The electro-optic (EO) properties of monoclinic BaTeMo2O9 (BTM) single crystals are studied using the interference technique by applying the external electric field. The measured room temperature free EO coefficients at 632.8 nm are 10.2 and 9.0 pm/V for γ12 and γ41, respectively. The EO effect (−12ni3γijE) of BTM is about three times as high as that of KH2PO4 (KDP) crystal, which makes it a very promising candidate for the EO applications.

Electro-optic and electromechanical properties of poled polymer thin films

A simple interferometric technique has been developed to sequentially measure the piezoelectric and electro-optic (EO) coefficient of the poled polymer films. This technique, similar to the Michelson interferometer, is based on compensating the change of the optical path due to the piezoelectric and electric-optic effect of the poled polymer films by opposite piezoelectric effect of a quartz crystal. Our technique has advantages of simplicity, high sensitivity, and improved accuracies over the previous ones. The experimental values of the EO coefficients agree with the values predicted by the two-level model.

Investigation of the dielectric, elastic, and piezoelectric properties of Cs2TeMo3O12 crystals

The complete sets of dielectric, elastic, and piezoelectric constants of Cs2TeMo3O12 crystals at room temperature were determined by means of the resonant technique and impedance analysis. The piezoelectric strain constants d33 and d15 were on the order of 20.3 and 29.2 pC/N, respectively, with the electromechanical coupling coefficients being k33 = 36.6% and k15 = 14.3%. Moreover, temperature dependence of the electro-elastic coefficients was measured in the range of 0–150 °C, where the elastic constant s44 was found to possess relatively low temperature coefficient (Ts44(1) = 77 × 10−6/ °C), and the variations of d33 and k33 were less than 3.5% and 1.0%, respectively.

Dielectric and ferroelectric properties of (Na0.8K0.2)0.5Bi0.5TiO3 thin films prepared by metalorganic solution deposition

(Na0.8K0.2)0.5Bi0.5TiO3 thin films have been prepared on Pt∕TiO2∕SiO2∕Si and p-type Si substrates using a metalorganic solution deposition method. The films annealed at 700 °C crystallize well and present perovskite phase. The films exhibit a well-defined hysteresis loop at an applied voltage of 4 V, with a remanent polarization of 4.7μC∕cm2 and a coercive field of 38kV∕cm. The films also show fatigue-free response up to 1.5×1010 switching cycles. The relaxor behavior of the films is confirmed by the frequency-dependence of capacitance-temperature relation. The capacitance-voltage curves show that the films are polarization-type switching and the memory window is about 2.5 V at ±4V applied dc bias voltages. The changes of dielectric constant and dissipation factor with frequency are also investigated briefly.

Temperature dependence of elastic properties and piezoelectric applications of BaTeMo2o9 single crystal [Correspondence]

BaTeMo2O9 (BTM) single crystal, as a lead-free piezoelectric material, belongs to the monoclinic system, space group P21. We report the temperature dependence of the elastic constants by the transmission method over the range -50°C to 150°C. The first-order temperature coefficients of the elastic constant s44 is about 180 × 10-6/°C. Piezoelectric resonators based on BTM crystal using the thickness-stretching vibration and the shear vibration modes were designed and evaluated, which eliminated or minimized the influence of the off-principal axis coefficients. The Qm of one of the resonators is about 600. Our results show that the elastic constants have good temperature stability, and the resonators have already met the requirements for some piezoelectric applications. This study on the BTM crystal has revealed the application for the low-symmetry crystal.

Refractive index dispersion measurement on nonlinear optical polymer using V-prism refractometer

By using V-prism refractometer, the refractive indices of a polyetherketone (PEK-c) guest-host polymer system were measured with the polymer in solutions. The Lorenz-Lorentz local field formalism was used in the calculation of the refractive indices of the polymers from the measured indices of the polymer solutions and the pure solvent by using V-prism refractometer. The refractive index dispersions of the polymers were obtained by fitting the measured indices of the polymers to Sellmeyer equation. The method allows for an accuracy in index of 0.7% in the determination of the polymer indices. In addition, a large difference between the indices of the polymer and the solvent, and a higher polymer volume fraction in the measured polymer solution are favorable for a high accuracy

Growth and electro‐elastic properties of K(H1−xDx)2PO4 single crystals

A series of K(H1−xDx)2PO4 crystals were grown from deuterated aqueous solution by using a point-seed rapid-growth method. The elastic, piezoelectric and dielectric constants of these crystals were determined using the resonance technique and impedance analysis, respectively. The elastic compliance constant s11 measured in this experiment is larger than that in previous experiments, and the reliability of the results presented herein has been verified. These results show that, with increasing content of deuterium, s11, s44, s66, d36, e36 and k36 are gradually increased, whereas s12, s13, s33, d14, e14 and k14 have no demonstrable variation. The reasons for the composition dependence of these constants were analyzed based on the variation of the crystal structures resolved by single-crystal X-ray diffraction.

PREPARATION AND CHARACTERISTICS OF Sm-DOPED Bi2Ti2O7 THIN FILMS

Crack-free Sm-doped Bi2Ti2O7 (Sm:Bi2Ti2O7) thin films with a strong (111) orientation have been prepared on p-Si(111) by chemical solution deposition (CSD). The structural properties and crystallizations were studied by X-ray diffraction. The surface morphology and quality were examined using atomic force microscopy (AFM). The dielectric constant and loss factor at different frequencies were also evaluated at room temperature. Their insulation was studied, too. The films exhibit better insulating property than does the pure Bi2Ti2O7.

Detwinning and domain removing of KIO3 crystal

This letter reports the detwinning and domain removing of KIO3 crystal. As a result, single domain KIO3 crystal with a size of 30×15×15 mm3 has been obtained.