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ABSTRACT: In this paper, a single crystal of 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 with dimensions of Φ 30×10mm 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 (T
m, ε
m) 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 1kHz for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal. The optimum poling conditions were
obtained by investigating the piezoelectric constants d
33 as a function of poling temperature and poling electric field. For the 〈001〉 and 〈110〉 crystal samples, the maximum d
33 values of 146 and 117 pC/N are obtained when a poling electric field of 3.5kV/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.
Applied Physics A 05/2012; 95(3):761-767. · 1.63 Impact Factor
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ABSTRACT: A 0.92Na0.5Bi0.5TiO3-0.08 K0.5Bi0.5TiO3 (0.92NBT-0.08KBT) lead-free piezoelectric single crystal with dimensions of Φ 35 × 10 mm was successfully grown by the top-seeded solution growth method. The effective segregation coefficient for K was calculated to be 0.27. An x-ray powder diffraction measurement showed that the as-grown crystal possesses a rhombohedral perovskite structure at room temperature. The room-temperature dielectric constants for poled 〈001〉, 〈110〉, and 〈111〉 oriented crystal samples are found to be 683, 567, and 435 at 1 kHz, respectively. The (Tm, ɛm) values for 〈001〉, 〈110〉, and 〈111〉 oriented crystals are (316 °C, 4318), (317 °C, 4160), and (318 °C, 4348) at 1 kHz, which indicate that the dielectric parameters of the as-grown crystals show weaker anisotropy. The curves, ɛ(T), for the three crystallographic orientations show two anomalies at about 170 and 320 °C, respectively, relating to the ferroelectric-antiferroelectric phase and the antiferroelectric-paraelectric phase. There is a thermal hysteresis, ΔT ≈ 35 °C for the ferroelectric-antiferroelectric phase transformation between heating and cooling. The antiferroelectric phase, the thermal hysteresis, and the dielectric relaxor behavior around 170 °C can be attributed to the formation of an intermediate orthorhombic modulated phase at 170–320 °C. For the 〈001〉, 〈110〉, and 〈111〉 crystal samples, the room-temperature piezoelectric constants, d33, reach 175, 130, and 70 pC/N, respectively. The remanent polarization for the 〈001〉, 〈110〉, and 〈111〉 crystal samples are 8.1, 10.8, and 13.5 μC/cm2, respectively, and the ratio is 1:1.33:1.67, close to 1::. The diffusive factors, α, are found to be 1.94, 1.91, and 1.50 for the 〈001〉, 〈110〉, and 〈111〉 oriented crystal samples, which indicate that the antiferroelectric-paraelectric phase transition of the as-grown 0.92NBT-0.08KBT crystal is a strong diffuse one. The electromechanical coupling coefficients for the 〈001〉, 〈110〉, and 〈111〉 oriented 0.92NBT-0.08KBT crystals at room temperature are 52, 50, and 48%, respectively. The values of kt for the three main crystallographic orientations change slightly with the increase of temperature from 15 to 140 °C, demonstrating a relatively stable thermal electromechanical coupling property.
Journal of Applied Physics 06/2011; 109(12):124113-124113-8. · 2.17 Impact Factor
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ABSTRACT: A systematic study of the optimized orientation and temperature dependence of shear-mode piezoelectric properties for ternary Pb ( In <sub>1/2</sub> Nb <sub>1/2</sub>) O <sub>3</sub>– Pb ( Mg <sub>1/3</sub> Nb <sub>2/3</sub>) O <sub>3</sub>– PbTiO <sub>3</sub> (PIN–PMN–PT or PIMNT) piezocrystals was carried out. It was found that [111]-poled samples presented the best shear piezoelectric properties when driving along [1 1 0] (the thickness direction). The electromechanical coupling coefficient k<sub>15</sub> and piezoelectric coefficient d<sub>15</sub> and g<sub>15</sub> were found to be 96.4%, 5966 pC/N, and 0.047 Vm/N, respectively, for optimum-cut samples with platinum (Pt) electrode. Besides, the maximum service temperature for shear mode is around 105 ° C , which is much higher than PMNT single crystals.
Journal of Applied Physics 05/2010; · 2.17 Impact Factor
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ABSTRACT: We investigated the dielectric, ferroelectric, and pyroelectric properties of Mn-doped 0.74 Pb ( Mg <sub>1/3</sub> Nb <sub>2/3</sub>) O <sub>3</sub>–0.26 PbTiO <sub>3</sub> crystals. Compared with pure PMN-0.26PT, Mn substitutions resulted in reduced dielectric loss and enhanced coercive field. Furthermore, the pyroelectric coefficient and detectivity figures of merits were enhanced to 17.2×10<sup>-4</sup> C / m <sup>2</sup> K and 40.2×10<sup>-5</sup> Pa <sup>-1/2</sup> , respectively, which were the highest values so far reported among intrinsic pyroelectric materials with rhombohedral-tetragonal phase transition temperature greater than 90 ° C . The specific detectivity of infrared detector based on Mn-doped crystals was 1.07×10<sup>9</sup> cm Hz <sup>1/2</sup> W <sup>-1</sup> , and approximately doubles that of commercial LiTaO <sub>3</sub> crystals-based, which makes them promising candidates for infrared detectors applications.
Applied Physics Letters 12/2009; · 3.84 Impact Factor
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ABSTRACT: High piezoelectric and ferroelectric properties have been found in Mn-doped Na0.5Bi0.5TiO3–BaTiO3 single crystals, which were grown by a top-seeded solution method. The electrical resistivity, dielectric constant, and ferroelectric and piezoelectric properties were all found to be notably enhanced by Mn. The piezoelectric constant d33 and electromechanical coupling coefficients kt and k31 were found to be as high as 483 pC/N, 0.56, and 0.40, respectively. These values are much higher than those previously reported for Pb-free piezoelectric crystals, demonstrating the real potential for alternative lead-free systems for sensor and piezoelectric applications.
Applied Physics Letters 09/2009; 95(10):102904-102904-3. · 3.84 Impact Factor
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ABSTRACT: The phase transitions of as-grown (1-x)PbMg(1/3)Nb(2/3)O(3)-xPbTiO(3) (PMN-xPT) crystals with PT compositions of x = 0.31 and 0.38 under a dc electric field were observed in a polarization microscope. The optical transmissions of the crystals under dc electric fields were measured in the wavelength region around their optical absorption edges. The band gaps of the orthorhombic and tetragonal phases under the applied electric field were obtained. By combining both of the optical methods, the phase transition from the tetragonal to the orthorhombic phase was observed in PMN-0.38PT crystals when the electric field along the [110](cub) direction reaches up to 300 V mm(-1). Whereas the PMN-0.31PT crystals undergo the pseudo-phase-transition under a dc electric field along the [110](cub) direction. The pseudo-phase-transition possibly stems from the reorientation and growth of microdomains in PMN-0.31PT crystals.
Journal of Physics Condensed Matter 08/2009; 21(33):335902. · 2.55 Impact Factor
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ABSTRACT: The phase transitions of as-grown (1−x)PbMg1/3Nb2/3O3–xPbTiO3 (PMN–xPT) crystals with PT compositions of x = 0.31 and 0.38 under a dc electric field were observed in a polarization microscope. The optical transmissions of the crystals under dc electric fields were measured in the wavelength region around their optical absorption edges. The band gaps of the orthorhombic and tetragonal phases under the applied electric field were obtained. By combining both of the optical methods, the phase transition from the tetragonal to the orthorhombic phase was observed in PMN–0.38PT crystals when the electric field along the [110]cub direction reaches up to 300 V mm−1. Whereas the PMN–0.31PT crystals undergo the pseudo-phase-transition under a dc electric field along the [110]cub direction. The pseudo-phase-transition possibly stems from the reorientation and growth of microdomains in PMN–0.31PT crystals.
Journal of Physics Condensed Matter 07/2009; 21(33):335902. · 2.55 Impact Factor
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Jing Chen,
Dan Zhou,
Feifei Wang,
Laihui Luo,
Bo Ren,
Yanting Lin,
Wenning Di,
Chao Chen,
Xiangyong Zhao,
Xiaoming Pan, Di Lin,
Haosu Luo
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ABSTRACT: The temperature dependence of the coupling constants kμν and piezoelectric constants dμν, gμν of transverse and shear mode 0.71Pb(Mg1/3Nb2/3)O3–0.29PbTiO3 (PMN–29%PT) single crystals with optimal orientation from room temperature to 115 °C were reported. From 20 °C to approximately 80 °C, k31 increases slightly from 91.0% to 93.5%, while d31 increases from 1900.0 to 4500.0 pC N−1. When the temperature exceeds 80 °C, both k31 and d31 begin to drop. Similarly, the coupling factor k15 increases from 95% to 97%, while the piezoelectric constant d15 increases from 4769.4 to 14293.2 pC N−1when the temperature rises from room temperature to 93 °C. When the temperature goes beyond 93 °C, the shear-mode piezoelectric properties start to decay. We also study the temperature dependence of the elastic compliances and , both of which show strong dependence of the temperature. The service temperature for PMN–29%PT is determined to be lower than 80 °C for transverse vibration and lower than 93 °C for shear-mode samples. These would effectively guide the correlative device designs and practical applications.
Journal of Physics D Applied Physics 12/2008; 42(3):035415. · 2.54 Impact Factor
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Wenwei Ge,
Hong Liu,
Xiangyong Zhao,
Bijun Fang,
Xiaobing Li,
Feifei Wang,
Dan Zhou,
Ping Yu,
Xiaoming Pan, Di Lin,
Haosu Luo
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ABSTRACT: A large single crystal of 0.95Na0.5Bi0.5TiO3–0.05BaTiO3 (0.95NBT–0.05BT) with dimensions of 35 mm diameter × 10 mm length was grown by the top-seeded-solution growth method (TSSG). X-ray powder diffraction results indicate that the as-grown 0.95NBT–0.05BT crystal is of a perovskite structure and belongs to the rhombohedral system. The dielectric, ferroelectric and piezoelectric properties were investigated in detail. The room temperature dielectric constants for unpoled 0 0 1, 1 1 0 and 1 1 1 oriented crystal samples are 1450, 1650 and 1750 at 1 kHz and decrease to 1050, 800 and 480 after poling. The remanent polarizations Pr of 0 0 1, 1 1 0 and 1 1 1 oriented crystal samples are 16.44 µC cm−2, 23.69 µC cm−2 and 27.63 µC cm−2 with the coercive fields Ec of 32.72 kV cm−1, 31.20 kV cm−1 and 28.15 kV cm−1, respectively. Interestingly, the piezoelectric constant d33 of the 0.95NBT–0.05BT crystal shows apparent anisotropy along its pseudocubic 0 0 1, 1 1 0 and 1 1 1 directions. The 0 0 1 poled 0.95NBT–0.05BT crystals show excellent piezoelectric properties with d33 = 280 pC N−1. However, the d33 values of the 1 1 1 oriented 0.95NBT–0.05BT crystal are only 90 pC N−1. The origin of apparent anisotropy in piezoelectric properties has been discussed in detail.
Journal of Physics D Applied Physics 05/2008; 41(11):115403. · 2.54 Impact Factor
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ABSTRACT: The elastic, piezoelectric, and dielectric properties of tetragonal 0.65 Pb ( Mg <sub>1/3</sub> Nb <sub>2/3</sub>) O <sub>3</sub>–0.35 Pb Ti O <sub>3</sub> (PMN-35%PT) single crystals were determined. The piezoelectric constant d<sub>33</sub> is ∼1250 pC / N ; the electromechanical coefficients k<sub>15</sub> , k<sub>31</sub> , k<sub>33</sub> , and k<sub>t</sub> are 0.70, 0.48, 0.91, and 0.61, respectively. The dielectric properties were measured as a function of temperature for (001)-oriented crystals. Compared with the crystals with compositions in the morphotropic phase boundary, PMN-35%PT crystals have much more stable phase structure from room temperature to Curie temperature, which makes them promising materials for high power applications in fabricating transducers, actuators, and generators.
Journal of Applied Physics 11/2006; · 2.17 Impact Factor
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Yanxue Tang,
Laihui Luo,
Yanmin Jia,
Haosu Luo,
Xiangyong Zhao,
Haiqing Xu, Di Lin,
Jinglan Sun,
Xiangjian Meng,
Junhao Zhu,
Mohammed Es-Souni
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ABSTRACT: 3 mol %Mn-doped 0.71Pb(Mg1/3Nb2/3)O3–0.29PbTiO3 single crystals were grown by a modified Bridgman technique. The pyroelectric properties and thermal stability of the crystals were investigated. Mn substitution resulted in an enhanced pyroelectric coefficient and a lower dielectric loss, which led to the improvement of the detectivity figure of merit of doped crystals by about a factor of 4 at 50 Hz compared with that of pure crystals. Moreover, the thermal stability was enhanced by Mn substitution. The mechanism of doping effect is explained by the fact that the domain walls are pinned by the dopant dipolar defects, which optimizes the pyroelectric performance of 0.71Pb(Mg1/3Nb2/3)O3–0.29PbTiO3 for uncooled infrared focal plane arrays applications.
Applied Physics Letters 10/2006; 89(16):162906-162906-3. · 3.84 Impact Factor
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ABSTRACT: The optical properties of 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 (PMN–0.35PT) single crystals were investigated by means of the optical transmittance spectrum. The refractive indices were measured in the visible region, and the dispersion behaviours of ordinary and extraordinary lights were well described in terms of the Wemple–Didomenico single oscillator dispersion model. The optical band gap values were obtained from the Tauc model. For (1 − x) Pb(Mg1/3Nb2/3)O3 − xPbTiO3 single crystals, as the PbTiO3 content increases, the refractive index increases, while the optical band gap energy decreases.
Journal of Physics D Applied Physics 09/2006; 39(20):4337. · 2.54 Impact Factor
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ABSTRACT: Electric-field-induced transverse strain behavior of (1−x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMNT/x) crystals with different cuts and compositions was investigated for using as electromechanical actuators. High transverse strain with low hysteresis was achieved for rhombohedral crystals near morphotropic phase boundary (28 ⩽ x ⩽ 30). Optimum crystallographic cut was found to be pseudocubic [001]L×[10]W×[110]T for rhombohedral crystals, exhibiting high transverse strain S1 ∼ −0.33% with hysteresis ∼ 8% and ultrahigh piezoelectric coefficient (d31) ∼ −3100 pC/N. When E field <6 kV/cm, the strain versus E-field curve is approximately linear, without obvious hysteresis. negative E field of −1.5 kV/cm can be applied to PMNT/x crystals with minimal hysteresis. However, strain behavior of PMNT/x crystals cut into [01]L×[11]W×[111]T or [100]L×[010]W×[001]T did not exhibit excellent properties as we expected. High transverse strain with low hysteresis makes PMNT/x crystals promising candidates for high-performance strain actuators.
Journal of Applied Physics 01/2006; 99(2):024104-024104-4. · 2.17 Impact Factor
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ABSTRACT: The pyroelectric properties of (1-x) Pb ( Mg <sub>1/3</sub> Nb <sub>2/3</sub>) O <sub>3</sub>–x Pb Ti O <sub>3</sub> ( PMN –x PT ) single crystals have been investigated over a broad composition range of 0.13≤x≤0.40 . The best pyroelectric performances are achieved in <111>-oriented PMN–0.26PT single crystal. At room temperature, the figures of merit for voltage responsivity and detectivity reach up to 0.11 m <sup>2</sup>/ C and 15.3×10<sup>-5</sup> Pa <sup>-1/2</sup> , respectively. These properties are superior to those of conventional pyroelectric ceramics that have been widely used in device applications. PMN–0.26PT single crystal also possesses a relative high Curie temperature (∼120 ° C ) and a low thermal diffusivity (∼4.4×10<sup>-7</sup> m <sup>2</sup>/ s ) . Furthermore, the pyroelectric properties of PMN –x PT (x≥0.26) single crystals are weak dependent on temperature and nearly independent of frequency in the experimental temperature range of 20–55 ° C and frequency range of 50–10 000 Hz . The superior pyroelectric performances of the single crystal make it a promising candidate for high-performance uncooled infrared detectors and thermal imagers.
Journal of Applied Physics 11/2005; · 2.17 Impact Factor
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ABSTRACT: A systematic study of the optical properties of tetragonal Pb ( Mg <sub>1/3</sub> Nb <sub>2/3</sub>)<sub>0.62</sub> Ti <sub>0.38</sub> O <sub>3</sub> single crystals was calculated out at room temperature. It was found that the crystal is transparent in the visible region and rolls off in near 450 nm. The optical absorption edge is around 400 nm under both unpoled and poled conditions. The refractive indices and their dispersion were accurately measured with the minimum deviation method. The parameters A<sub>i</sub>, B<sub>i</sub>, C<sub>i</sub>, and D<sub>i</sub> of Sellmeier’s equation for both n<sub>o</sub> and n<sub>e</sub> are also obtained in terms of least-squares fit. Then, the refractive indices in the wavelength range of 435.8–3100 nm can be calculated. Using the Senarmont compensator method, the effective electro-optic coefficient r<sub>c</sub>=42.8 pm / V was also obtained. Some discussions about the octahedral BO <sub>6</sub> structure are presented on the optical properties of the material. © 2003 American Institute of Physics.
Journal of Applied Physics 05/2003; · 2.17 Impact Factor
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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 25 mm × 10 mm 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 = 3.8862 Å and α = β = γ = 89.2°. At room temperature, the dielectric constant of <0 0 1> oriented NBBT98/2 crystal is 770 at 10 kHz and it decreases to 430 after poling under the E-field of 7 kV/mm. Maximum d33 values of 60, 65 and 30 pC/N were obtained for <0 0 1>, <1 1 0> and <1 1 1> oriented NBBT98/2 crystal, respectively.
Journal of Alloys and Compounds.
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ABSTRACT: The method to distinguish two types of monoclinic phases (MA and MB) in perovskite crystals by polarized light microscopy was developed. The MA-type monoclinic phase was observed in xPb(In1/2Nb1/2)O3–yPb(Mg1/3Nb2/3)O3–zPbTiO3 ternary crystal by polarized light microscopy at room temperature. The phase transition of these monoclinic phases under dc electric field along [1 1 0]cub direction was investigated in real time. Two dielectric peaks were found in ferroelectric phases of the as-grown ternary single crystals near the morphotropic phase boundary (MPB) with increasing temperature, which indicate the phase transition of monoclinic MA → orthorhombic (O) → tetragonal (T).
Materials Chemistry and Physics 122:350-353. · 2.23 Impact Factor
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ABSTRACT: Relaxor-based ferroelectric single crystals Mn doped 0.72Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 (Mn–PMN–0.28PT) were grown by the modified Bridgman technique. The effects of nitrogen annealing on structural quality, defect and electrical properties of [1 1 1]-oriented Mn–PMN–0.28PT were systematically investigated. X-ray rocking curves (XRC) were used and the results indicated that the quality of single crystals could be significantly improved by appropriate annealing. X-ray photoelectron spectroscopy (XPS) was used to investigate the content and valence states of main elements in Mn–PMN–0.28PT, including oxygen vacancies. The conduction mechanisms at different temperature ranges were discussed. The dielectric loss of annealed samples decreased about 50% compared to the unannealed one, which should be attributed to the motion of domain walls pinned by defects. The pinning effect caused by oxygen vacancies on domain wall motion was enhanced through nitrogen annealing and the pyroelectric performances were optimized.
Journal of Crystal Growth 318(1):865-869. · 1.73 Impact Factor
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ABSTRACT: A ternary relaxor ferroelectric single crystal Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 was grown by the modified Bridgman method. The real compositions, phase structures and performances of different regions in the boule were characterized. The real composition deviated from the nominal composition, but the In/Pb ratio in the crystal remained nearly a constant. The piezoelectric coefficient d33, electromechanical coupling factor k33 and coercive field Ec after 〈0 1 1〉 poling can reach up to 1500 pC/N, 0.90 and 4 kV/cm, respectively. More importantly, the rhombohedral to tetragonal phase transition temperature (Trt) in PIN–PMN–PT single crystal with rhombohedral composition increased to 114 °C, which made the ternary system single crystal fit for the applications in wider temperature range.
Journal of Crystal Growth 318(1):890-894. · 1.73 Impact Factor
