Search

The [111]‐oriented rhombohedral Mn‐doped 0.15Pb(In1/2Nb1/2)‐0.55Pb(Mg1/3Nb2/3)O3‐0.30PbTiO3 (Mn:PIMNT(15/55/30)) crystal and the [001]‐oriented tetragonal Mn‐doped 0.29Pb(In1/2Nb1/2)‐0.29Pb(Mg1/3Nb2/3)O3‐0.42PbTiO3 (Mn:PIMNT(29/29/42)) crystal were poled under different conditions. The pyroelectric performance of the two crystals as a function of poling temperature, as well as the relationship with ferroelectric domain configuration and phase structure was investigated systematically. The pyroelectric properties of the two crystals enhance with rising the poling temperature, which can be attributed to the improvement of the single state. And for the rhombohedral Mn:PIMNT(15/55/30) crystal locating near morphotropic phase boundary (MPB), the increase of tetragonal phase induces the deterioration of pyroelectric properties. Due to more residual tetragonal phase, the pyroelectric coefficient of the Mn:PIMNT(15/55/30) crystal poled at 150°C is lower than that poled at 100°C. In general, both the crystals poled above TC achieve nearly single state, exhibiting the best pyroelectric properties with relatively high Curie temperature (TC), where P = 9.71 × 10−4 C m−2 K−1, Fi = 3.88 × 10−10 m V−1, Fv = 0.068 m2 C−1 and Fd = 29.7 × 10−5 Pa−1/2 for the rhombohedral Mn:PIMNT(15/55/30) crystal (TC = 171°C) and P = 6.78 × 10−4 C m−2 K−1, Fi = 2.71 ×10−10 mV−1, Fv = 0.1 m2 C−1, Fd = 23.54 × 10−5 Pa−1/2 for the tetragonal Mn:PIMNT(29/29/42) single crystal (TC = 251°C), meeting the stable operation of infrared detector at relatively high environmental temperatures. [ABSTRACT FROM AUTHOR]

Piezoelectric constant and temperature vs dielectric constant measurements have been performed on the <001> and <011> oriented Pb(Mg[SUB1/3]Nb[SUB2/3])O[SUB3]-PbTiO[SUB3] crystals in the rhombohedral phase with compositions near the morphotropic phase boundary under different poling fields. The investigations have revealed that the dielectric and piezoelectric properties strongly depend on composition (PbTiO[SUB3] content), and on poling field for crystals in a narrow composition region. The influence of composition on the stability of orthorhombic ferroelectric phase has been identified by x-ray diffraction on the <011> oriented crystals. And the origin of high piezoelectric response for crystals in different composition regions was proposed. [ABSTRACT FROM AUTHOR]

In this paper, a single crystal of 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 with dimensions of Φ 30×10 mm was grown by the top-seeded-solution growth method. X-ray powder diffraction results show that the as-grown crystal possesses the rhombohedral perovskite-type structure. The dielectric, piezoelectric and electrical conductivity properties were systematically investigated with 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples. The room-temperature dielectric constants for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples are found to be 650, 740 and 400 at 1 kHz. The ( Tm, εm) values of the dielectric temperature spectra are almost independent of the crystal orientations; they are (306°C, 3718), (305°C, 3613) and (307°C, 3600) at 1 kHz for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal. The optimum poling conditions were obtained by investigating the piezoelectric constants d33 as a function of poling temperature and poling electric field. For the 〈001〉 and 〈110〉 crystal samples, the maximum d33 values of 146 and 117 pC/N are obtained when a poling electric field of 3.5 kV/mm and a poling temperature of 80°C were applied during the poling process. The as-grown 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 crystal possesses a relatively large dc electrical conductivity, especially at higher temperature, having a value of 1.98×10−11 Ω−1⋅m−1 and 3.95×10−9 Ω−1⋅m−1 at 25°C and 150°C for the 〈001〉 oriented crystal sample. [ABSTRACT FROM AUTHOR]

The dielectric and piezoelectric properties of the Mn-doped 0.71Pb(Mg1/3Nb2/3)O3–0.29PbTiO3 (PMNT) crystals oriented along <001> and <110> directions, respectively, have been investigated. The investigations have shown that 3 at.% Mn substitution results in (i) a large increment of coercive field at the cost of piezoelectric response, (ii) an increased Curie temperature and an enhanced stability of the ferroelectric rhombohedral phase, which enable a wider operation temperature range, and (iii) enhanced linearity in electric field induced strain with lower hysteresis. The hardened PMNT crystals favor their applications in high power transducers. [ABSTRACT FROM AUTHOR]

This letter presents the experimental results of self-pumped phase conjugation (SPPC) in barium titanate (BaTiO[sub 3]) crystals doped with Rh or Ce. It has been shown that the main parameters of SPPC depend very strongly on the concentration of dopants, the incident angles, and the cut type of the crystals. Some qualitative explanation of the experimental results are also given. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, polycrystalline material of 0.94Na0.5Bi0.5TiO3–0.06BaTiO3 (abbreviated as NBBT94/6) was synthesized by solid-state reaction techniques. DTA and TG analysis indicate the proper temperature for solid-state reaction is 1200°C. A single crystal with dimensions of 25mm×10mm was successfully grown by using the top-seeded solution growth (TSSG) method. X-ray fluorescence analysis revealed that the composition of the as-grown crystal is NBBT98/2. X-ray powder diffraction results show that the as-grown NBBT98/2 crystal possesses the perovskite structure and belongs to the rhombohedral system. The unit-cell constants of the as-grown NBBT98/2 crystal are a = b = c =3.8862Å and α = β = γ =89.2°. At room temperature, the dielectric constant of <001> oriented NBBT98/2 crystal is 770 at 10kHz and it decreases to 430 after poling under the E-field of 7kV/mm. Maximum d 33 values of 60, 65 and 30pC/N were obtained for <001>, <110> and <111> oriented NBBT98/2 crystal, respectively. [Copyright &y& Elsevier]

In this paper, 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 (PMNT69/31) single crystals have been investigated on their shear-mode piezoelectric properties as a function of crystal orientation and electrode material using resonance techniques. Three types of electrodes, coated graphite and sputtered Au or Cu, were applied. It was found that the largest stress is produced by applying a field along the 〈11¯0〉 direction combined with a poling along the 〈111〉 direction. In this case, piezoelectric coefficients d15, g15 and electromechanical coupling coefficient k15 had values of 3689 pC/N, 0.0318 V m/N and 93.3%, respectively, for samples with graphite electrode. However, much better piezoelectric properties with d15, g15, and k15 of 5980 pC/N, 0.056 V m/N and 97.0%, respectively, were obtained as the samples with Cu electrode. Our results suggest that these 〈111〉-oriented crystals are promising materials for shear transducer. [Copyright &y& Elsevier]