Low Temperature Sintering And Properties Of PMMNS Piezoelectric Ceramics

In recent years, as the electronic equipments integrated and becoming smaller, the tradition electromagnetic transformers dose not adapted to the electronic equipm ents development because of many weakness, such as big bulk,ponderosity and easily interfered by electromagnetism.Thus the development of a new generation of transfo rmers becomes a hot topic in the world, the nicer quality of piezoelectric transformer could resolved the electromagnetic transformer's problem. so, the piezoelectric transfo rmer has great application prospect. and the technical difficulty to develop the multi-layer piezoelectric transformer is to obtain piezoelectric ceramics with highperform ance and low sintering temperature. In order to resolve this problem, investigation has beem performed in this dissertation, including:The influence of the addition of SiO2 on crystallographic phase and electromechanical properties of the PMMNS piezoele ctric ceramics; The PMMNS of low sintering temperature using CuO-SiO2-Bi2O3-Ni2O3-Co2O3-Li2CO3 as sintering agents; studied and improved the PMMNS formula using orthogonal design.grip the effect of every sintering agents and the changing tre nd of experiment result as the variety of addition.PMMNS+xSiO2 quintuple piezoelectric ceramics were prepared by solid-solution processing,and the effects of different addition of SiO2 on the microstructure and ele-ctric properties were investigated.The experimental results indicate that pure perovsk-ite structure was obtained in the sintering temperature range. With the increasing of the addition phases shift from tetragonal phase to rhombohedral phase,and the mechan ical quality factor Qm,Dielectric constantεr electromechanical coupling factor Kp and piezoelectric constant d33 increase with the increasing of the addition and then decrease, whereas, dielectric loss tanδreduce.When x was 0.10 wt%, the optimum d33, Kp Qm tanδandεr were obtained, they are Kp=0.51,d33=323 PC/N,Qm=1475,tanδ=0.0038,εr= 1762 respectively.on the basis of understanding of the PMMNS, devised the PMMNS formula using the orthogonal design.The effects of addition the CuO-SiO2-Bi2O3-Ni2O3-Co2O3-Li2CO3 as sintering agents on the microstructure and electric properties were investigated.Results show that phase structure, piezoelectric and dielectric properties of PMMNS ceramics had different sensitivity to the addition. And the experimental results were different as the changeing of addition. We could find the best formula while we did the lest experiment.