Dielectric properties and relaxor behavior of rare-earth (La, Sm, Eu, Dy, Y) substituted barium zirconium titanate ceramics

摘要

Based on the Ti-vacancy defect compensation model, (Ba_(1-x)Ln_x)Zr_(0.2)Ti_(0.8-x/4)O_3 (Ln =La,Sm,Eu,Dy,Y) ceramics have been fabricated via the conventional solid-state reaction method. The microstructures, dielectric properties, and ferroelectric relaxor behavior of (Ba_(1-x)Ln_x)Zr_(0.2)Ti_(0.8-x/4)O_3 ceramics have been investigated. The results indicate that rare-earth ions with various ionic radii enter the unit cell to substitute for A-site Ba~(2+) ions and inhibit the grain growth. The typical ferroelectric relaxor behavior is induced due to the rare-earth ions substitution. The diffuseness of the phase transition and the degree of ferroelectric relaxor behavior are enhanced, the T_c is remarkably shifted to lower temperature, and the tunability is suppressed with the increase of x value and substituted ionic radius for (Ba_(1-x)Ln_x)Zr_(0.2)Ti_(0.8-x/4)O_3 (x=0.005-0.04, Ln =La,Sm,Eu,Dy, Y) ceramics. Tunable ferroelectric materials with moderate dielectric constant and low dielectric loss can be obtained by manipulating the doping amount of suitable rare-earth ions.