Shaobo Guo

Enhanced pyroelectric properties of Cax(Sr0.5Ba0.5)1−xNb2O6 lead-free ceramics

Cax(Sr0.5Ba0.5)1−xNb2O6 [CSBN(x), x = 0.00, 0.10, 0.15, and 0.20] lead-Free ceramics were prepared by a traditional solid-state reaction technique. Dielectric, ferroelectric, and pyroelectric properties of CSBN(x) lead-Free ceramics were systematically investigated. The pyroelectric properties of CSBN(x) have been enhanced remarkably due to Ca addition and reached the maximum values at x = 0.15, with pyroelectric coefficient of 3.61 × 10−8 C/cm2 K and pyroelectric figure of merit of Fi = 172 pm/V, Fv = 0.021 m2/C, and Fd = 11.5 μPa−1/2, which are superior to other lead-free ferroelectric ceramics. These results indicate the potential of CSBN(x) ceramics for infrared detector applications.

High performance Bi0.5Na0.5TiO3-BiAlO3-K0.5Na0.5NbO3 lead-free pyroelectric ceramics for thermal detectors

Both high pyroelectric properties and good temperature stability of ferroelectric materials are desirable when used for applications in infrared thermal detectors. In this work, we report lead-free ternary 0.97(0.99Bi0.5Na0.5TiO3-0.01BiAlO3)-0.03K0.5Na0.5NbO3 (BNT-BA-KNN) ceramics, which not only exhibits a large pyroelectric coefficient (p ∼ 3.7 × 10−8 C cm−2 K−1) and figures of merit (Fi, Fv, and Fd) but also shows excellent thermal stable properties. At room temperature, Fi, Fv, and Fd are determined as high as 1.32 × 10−10 m/V, 2.89 × 10−2 m2/C, and 1.15 × 10−5 Pa−1/2 at 1 kHz and 1.32 × 10−10 m/V, 2.70 × 10−2 m2/C, and 1.09 × 10−5 Pa−1/2 at 20 Hz, respectively. During the temperature range of RT to 85 °C, the achieved p, Fi, Fv, and Fd do not vary too much. The high depolarization temperature and the undispersed ferroelectric-ergodic relaxor phase transition with a sharp pyroelectric coefficient peak value of ∼400 × 10−8 C cm−2 K−1 are suggested to be responsible for this thermal stability, which ens...

Enhanced pyroelectric properties of Pb0.3Ca0.15Sr0.55TiO3 ceramic with first-order dominated phase transition under low bias field

We introduce a system of ferroelectric materials, Pb0.3CaxSr0.7-xTiO3 [PCST(x), x = 0.00, 0.05, 0.10, and 0.15], which exhibit good pyroelectric properties near room temperature. The enhanced field-induced pyroelectric coefficient of PCST(0.15) reached 81.8 × 10−8 C/cm2 K and it exhibited the largest voltage response with a dynamic black-body radiation measurement under a DC bias field of 200 V/mm. Systematic dielectric and phase transition analysis of the PCST(x) ceramics demonstrated that the phase transition gradually changed from a second-order to first-order dominated one with increasing Ca ion substitution. The enhanced pyroelectric properties under such a low bias field in the vicinity of room temperature of the PCST(0.15) ceramic are highly desirable for infrared detecting applications.

Conduction of (Na,Ce) doped Bi5Ti3FeO15 ceramics after different annealing processes

Abstract Abstract Bi5−xNax/2Cex/2Ti3FeO15 (BNTF-100x, x = 0, 0·05, 0·10, 0·20, 0·30, 0·40 and 0·60) ceramics were prepared via solid state sintering process. With x increasing, the resistivity increases at first and then decreases. The lower the concentration of oxygen vacancies, caused by more (Na,Ce) dopant adding, the less the deep trap energies in the band gap for the activated electrons to be mobile. For the samples containing high concentration of oxygen vacancies, the conductivities are higher when they are annealed in the air and oxygen than that in the vacuum. On the contrary, for the samples containing low concentration of oxygen vacancies, the conductivities of the samples in different annealing conditions behave quite the same way. Most (Na,Ce) doped Bi5Ti3FeO15 ceramics exhibit intrinsic conduction at high temperatures with corresponding activation energies of 1·1–1·6 eV, while the extrinsic conduction has a close relationship with the concentration of oxygen vacancies and the activation ability of electrons.

Properties Evaluation of Piezoelectric Materials in Application of Cochlear Implant

Piezoelectric materials for their particular acoustic-electric transition characteristics could be used to cochlear implant. A series experiments both in vitro and vivo were described in this paper so as to understand the function of different parameters for acoustic-electric transition in the hydrostatic environment of inner ear. The vitro experiment indicated that the voltages produced by piezoelectric materials were mainly concerned with the hydrostatic piezoelectric voltage coefficient gh. The vivo experiment substantiated the feasibility of piezoelectric cochlear again and further analysis showed that factor of merit could be a better parameter to evaluate the properties of piezoelectric materials in application of cochlear implant.