In this article, the studies of the polarization currents and current–voltage characteristics (J–V) are presented. The measurements of the J–V in low and high temperatures as well as at low and high voltages have permitted to recognize certain details of local energy levels in forbidden gap. It has been possible to calculate energy trap levels and their concentration. Calculated trap energy and concentration, under the condition of single trap energy levels, are equal: Et = 0.55 eV, Nt = 2.97 · 1023 m?3 for the sample y = 0.44 and Et = 0.59 eV, Nt = 1.5 · 1023 m?3 for the sample y = 0.47. Knowing the J–V characteristic and the Seebeck coefficient the carriers concentration and their mobility can also be calculated. The carriers concentration and their mobility are equal: n = 3.8 · 1018 m?3, µ = 1.4 · 10?12 m2 V?1 · s?1 for sample y = 0.44 and n = 6.9 · 1016 m?3, µ = 1.3·10?11 m2 V?1 · s?1 for the sample y = 0.47. 相似文献
The effect of antimony dopant on phase transition, dielectric response and relaxor behaviour of (Pb0.75Ba0.25)(Zr0.70Ti0.30)O3 ceramics was studied. Ceramic samples, with various Sb concentration from the range 1 to 4 at.%, were prepared by a conventional mixed oxide method. The crystal structure of the investigated ceramics was determined by an X-ray diffraction at room temperature that allowed to determine the unit cell parameters. Dielectric relaxation typical for ferroelectric relaxors was observed in the vicinity of diffuse ferroelectric–paraelectric phase transition. All parameters describing the relaxor behaviour determined from the Vogel–Fulcher relationship depend on the concentration of Sb dopant. The strong influence of antimony on grain structure and on remanent polarisation was confirmed as well. 相似文献
The objective of this work is to investigate the dependence of the electric behavior on shock pressure in Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 (PZT 95/5-2Nb) and Pb0.99[(Zr0.90Sn0.10)0.96Ti0.04]0.98Nb0.02O3 (PZST) ferroelectric ceramics under shock wave compression. PZT 95/5-2Nb and PZST ceramics were subjected to high dynamic pressure generated by plate impacts. The output currents were measured under the short-circuit condition in the pressure range from 0.23 to 4.50 GPa. The evolution of the electric response exhibits three distinct regions: (1) Below the critical phase transition pressure (σC), alternate negative and positive piezoelectric currents are observed and the corresponding piezoelectric constant is e31. (2) Above σC and below the complete phase transition pressure (σH), released charge increases with increasing shock pressure, illustrating the transition of ferroelectric to antiferroelectric phase. (3) Above σH, the output current is insensitive to the shock pressure. A similar evolutionary process is also observed in hydrostatic and uniaxial stress experiments. 相似文献
Perovskite type Ba1?xSrxTi0.6Zr0.4O3 (with x = 0.0, 0.1, 0.2, 0.4 and 0.5) ceramics have been synthesized through solid oxide reaction route. The room temperature XRD study suggests the compositions have single phase cubic symmetry. Microstructural studies have shown a step decrease in grain size. The dielectric study reveals that the materials are of relaxor type and undergo a diffuse type ferroelectric phase transition. The diffusivity increases with increase in Sr contents in the studied composition range. The transition temperature decreases with increase in Sr contents due to the decrease in grain size. 相似文献
The multiferroic Pb(Fe1/2V1/2)O3 (PFV) bulk ceramic was fabricated by a conventional ceramic sintering method. The strong visible‐light photovoltaic effect in Sn‐doped‐In2O3(ITO)/PFV/ITO structure capacitor was observed. The open‐circuit voltage was up to ～0.7 V, which was much higher than the value (～0.3 V) in BiFeO3 film. The photo‐excited electric current is almost proportional to the incident light illumination intensity. The good visible‐light photovoltaic makes PFV ceramic a potential candidate for practical application in solar cell devices.
The dielectric and pyroelectric responses of MgO-modified Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 ceramics were investigated near FR(LT)–FR(HT) phase transition. It was found that MgO additive reduced the FR(LT)–FR(HT) phase transition temperature from 41 °C to room temperature (24 °C). Superior room-temperature pyroelectric properties were obtained in the composition of 0.10 wt% MgO addition without DC bias. The largest pyroelectric coefficient, 65 × 10−8 C cm−2 K−1, was detected. Accordingly, the detectivity figures of merit Fd had maximum values of 20 × 10−5 Pa−1/2, and especially the voltage responsivity Fv = 0.91 m2C−1 is the highest value reported so far among all pyroelectric materials. It shows promising potential for application in uncooled pyroelectric infrared detector. 相似文献
High Curie temperature (TC) xBi(Ni1/2Ti1/2)O3-(1-x)Pb(Zr1/2Ti1/2)O3 (xBNT-(1-x)PZT, BNT-PZT) piezoelectric ceramics were prepared by the conventional ceramic processing. The composition-induced morphotropic phase boundary (MPB) and its influences on structure and electrical performance were investigated. The synthesized BNT-PZT ceramics exhibit rather pure perovskite structure, and densified microstructure morphology with uniform elementals distribution in both grains and grain boundaries. With increasing the content of Bi(Ni1/2Ti1/2)O3 (BNT), crystal structure of the BNT-PZT ceramics transform from tetragonal phase to rhombohedral phase, and dielectric response peaks change from narrow shape to very broad shape but all presenting dielectric frequency dispersion. The diffused and relaxation dielectric behavior can be fitted well by the quadratic law, and the Vogel-Fulcher law fitting provides additional information on the relaxation characteristic. The MPB effects are confirmed further by ferroelectric and piezoelectric properties measurements. High-TC combined with excellent piezoelectric performance can be realized in the BNT-PZT system, which presents promising applications in geothermal exploration, aerospace and related elevated temperatures fields. 相似文献
The dielectric and piezoelectric properties of pyrochlore-free lead zirconate titanate-lead zinc niobate ceramics were investigated systematically as a function of Sr doping. The powders of Pb(1?x)Srx[0.7(Zr1/2Ti1/2)–0.3(Zn1/3Nb2/3)]O3, where x?=?0–0.06 were prepared using the columbite-(wolframite) precursor method. The ceramic materials were characterized using X-ray diffraction, dielectric spectra, hysteresis and electromechanical measurements. The phase-pure perovskite phase of Sr-doped PZN--PZT ceramics was obtained over a wide compositional range. The results showed that the optimized electrical properties were also achieved at composition x?=?0.0, which were KP?=?0.69, d33?=?670?pC?N?1, Pr?=?31.9?µC?cm?2 and εrmax?=?18600. Maximum dielectric constant values of the systems decreased rapidly with increasing Sr concentration. Moreover, with increasing Sr concentration dielectric constant versus temperature curves become gradually broader. The diffuseness parameter increased significantly with Sr doping. Furthermore, Sr doping has been shown to produce a linear reduction in the transition temperature (Tm)?=?294.1–12.7x°C with concentration (x). Sr shifts the transition temperature of this system at a rate of 12.7°C?mol?1%. 相似文献
Effects of BiFeO3 (BFO) content on the microstructure and electrical properties of Ba0.85Ca0.15Ti0.90Zr0.10O3 (BCTZ) ceramics prepared by normal sintering in air were investigated. A stable solid solution is formed between BCTZ and BFO. The grain size gradually becomes smaller, and the ceramics become denser with increasing the BFO content. The Curie temperature, dielectric constant, and dielectric loss of BCTZ ceramics decrease simultaneously with the introduction of BFO. Moreover, the remanent polarization reaches a maximum at x = 0.2 mol%, and the coercive field continuously increases with increasing the BFO content due to the introduction of BFO with a higher coercive field. Improved piezoelectric properties (d33 ∼ 405 pC/N and kp ∼ 0.44) are demonstrated for the BCTZ ceramic with x = 0.2 mol%. 相似文献
The binary system of 0.8Pb(Zr1/2Ti1/2)O3–0.2Pb(Ni1/3Nb2/3)O3 ceramics were synthesized by conventional mixed oxide and columbite method. X-ray diffraction analysis demonstrated the coexistence of both the rhombohedral and tetragonal phases for the columbite prepared sample. Rhombohedral to tetragonal phase transition for columbite method was different compared with those of the mixed oxide method. The permittivity shows a shoulder at the rhombohedral to tetragonal phase transition temperature TRho–Tetra = 195 °C, and then a maximum permittivity (36,000 at 10 kHz) at the transition temperature Tm = 277 °C on ceramics prepared with the columbite method. However, piezoelectric coefficient (d33) was measured to be 282 pC/N for the conventional method and higher than the columbite method. The results were related to the phase compositions and porosity of the ceramics. 相似文献
