A modified sol-gel method is used for synthesizing Nd ion doped lead zirconate titanate nanopowders Pb1–3x/2NdxZr0.52Ti0.48O3 (PNZT) in an ethylene glycol system with zirconium nitrate as zirconium source. The results show that it is critical to add lead acetate after the reaction of zirconium nitrate with tetrabutyl titanate in the ethylene glycol system for preparing PNZT with an exact fraction of titanium content. It has been observed that the dopant of excess Nd ions can effectively improve the sintered densification and activity of the PNZT ceramics. Piezoelectric, dielectric and ferroelectric properties of the PNZT ceramics are remarkably enhanced as compared with those of monolithic lead zirconate titanate (PZT). Especially, the supreme values of piezoelectric constant (d33) and dielectric constant () for the PNZT are both about two times that of the monolithic PZT and moreover, the remnant polarization (Pr) also increases by 30%. According to the analysis of the structures and properties, we attribute the improvement in electrical properties to the lead vacancies caused by the doping of Nd ions.

http://iopscience.iop.org/article/10.1088/1674-1056/18/6/079/pdf

Structural and electrical properties of Nd ion modified lead zirconate titanate nanopowders and ceramics

Pyrolytic carbon-Si 3 N 4 ceramics (PyC-Si 3 N 4 ) with gradient PyC distribution (Gradient-PyC-Si 3 N 4 ) is fabricated by directional oxidation. After directional oxidation for 1.0 h, the electromagnetic absorptivity of Gradient-PyC-Si 3 N 4 increases significantly from 0.8 to 50.1% with the obvious reduction of electromagnetic reflectivity from 99.2 to 43.8%. The Gradient-PyC-Si 3 N 4 is a good electromagnetic absorbing material meeting the requirement of self-concealing technology.

Electromagnetic properties of pyrolytic carbon-Si3N4 ceramics with gradient PyC distribution

Electromagnetic properties of porous Si3N4 ceramics with gradient distributions of SiC and pores fabricated by directional in–situ nitridation reaction

Preparation and performance of electromagnetic wave absorbing foamed ceramics with high closed porosity and gradient SiC distribution

Pb(Zr0.53, Ti0.47)O3 (PZT) films with thicknesses of 0.8μm, 2μm and 4μm are prepared by a sol-gel method and their longitudinal piezoelectric coefficients are analysed. The results show that the PZT thick films, whose density is closer to bulk PZT, has the better crystallization, with d33 and density much larger than those of PZT thin films. A piezoelectric microcantilever actuated by a 4-μm-thick PZT film is fabricated and its displacement is measured in different frequencies and voltages. The displacement increases linearly with the increasing bias, and the maximum displacement of 0.544 μm is observed at 30kHz for 5V bias. The resonant frequency obtained in the experiment matches quite well with the theoretical result, and it is shown that the resonant frequency of PZT microcantilever could be controlled and predicated.

https://iopscience.iop.org/article/10.1088/0256-307X/25/11/079/pdf

Electromechanical Properties of Microcantilever Actuated by Enhanced Piezoelectric PZT Thick Film

Design of Functionally Graded Materials towards RAM and their Microwave Reflectivity

A sol-gel technology to fabricate PZT thick film for cantilever beam was investigated. In this process, PZT nano-powder is dispersed into a PZT sol solution, which is identical with the powder in composition, and then the PZT suspension and clean PZT sol solution were deposited alternately on an Au/Cr/SiO2/Si substrate using spin-coating route. Above process was repeated in order to deposit the desired thickness. The results showed that the perovskite PZT thick film with thickness of about 4 μm was obtained after annealing at 650 °C for 2 h and it has the saturation polarization of 54 μC/cm2, the remnant polarization of 30 μC/cm2 and the coercive field of 50 kV/cm.

Cheng Jun Qiu

Papers

Design of Functionally Graded Materials towards RAM and their Microwave Reflectivity

Fabrication of Piezoelectric Cantilever Beam Based on Nanostructured PZT Film