The Investigation Of Properties And Preparation Process Of Barium Titanate Base Lead-free Electrostriction Ceramics

Barium titanate base ceramic is one of the important ferroelectric materials withperovskite structure, which has been used as multi-layer ceramic capacitor and soforth because of its excellent piezoelectric, pyroelTahrgee s thrayisnte irse saiss hbilgohc kass～its1%ap ipnl icthaeti ofonrsm a so fa baacrtiuuamlto etcri ttariancna dta enm sdii cnfrgeolr erod icesrlpyelscattcarelisc properties.m, ehnotw deevveirc eamaterial. The0.5Ba(Zr_xTi_1-x)O₃-0.5(Ba_0.75Ca_0.25)TiO₃（x=0.25,0.30,0.35,0.40） ceramicspecimens were prepared by a conventional solid-state reaction route using powdersof BaCO₃, CaCO₃, TiO₂and ZrO₂as starting materials in this paper. Firstly, theeffects of zirconium content and sintering temperature on the microstructures,dielectric and electrostrictive properties of0.5Ba (Zr_xTi_1-x)O₃-0.5(Ba_0.75Ca_0.25)TiO₃ceramics had been investigated systematically. Secondly, it is necessary to reduce thesintering temperature because of this system with higher sintering temperature anddifficult to burn into the product with high density. The Al2O₃-SiO₂-CaO was used toachieve the goal of reducing the sintering temperature. The effects of sintering agentcontent on the microstructures, dielectric and electrostrictive properties of0.5Ba(Zr_0.35Ti_0.65)O₃-0.5(Ba_0.75Ca_0.25)TiO₃ceramics had also been investigated.Through the study in this paper, it shows a diffuse phase transition around thetransition temperature, the diffuse transition behavior is enhanced with increasing Zrcontent, indicating a composition-induced diffuse transition and Curie temperaturemove to room temperature. The corresponding maximum strain were0.156%,0.110%,0.082%, and0.071%, electrostrictive coefficient were0.079m⁴C^-2,0.063m⁴C^-2,0.053m⁴C^-2and0.059m⁴C^-2, respectively, for0.5Ba(Zr_xTi_1-x)O₃-0.5(Ba_0.75Ca_0.25)TiO₃（x=0.25,0.30,0.35,0.40） ceramic sintering at1450°C.The improvement of sinteringtemperature has less effects on dielectric constant and dielectric loss of the ceramicwith x=0.35.With the increasing sintering temperature, the maximum strain andelectrostrictive coefficient of the ceramic with x=0.35decreases.The sintering agent had huge influence on properties of ceramic, especially on it’sdielectric properties. The SEM showed that0.5Ba(Zr_0.35Ti_0.65)O₃-0.5(Ca_0.25Ba_0.75)TiO₃sintering at1200°C couldn’t be sintered completely and grain size didn’t grow up, andXRD patterns showed the second phase Ba2TiSi2O8existed, but the second phasedisappeared when sintering temperature improved; with the increase in sintering agentcontent, the maximum strain were0.042%,0.055%,0.064%and0.055%, the electrostrictive coefficient were0.027m⁴C^-2,0.063m⁴C^-2,0.142m⁴C^-2and0.263m⁴C^-2, respectively, when sintering at1250°C.