Effects of Mn doping on dielectric properties of ferroelectric relaxor PLZT ceramics

Abstract A series of PLZT (8/65/35) ceramics with different Mn 2 O 3 concentration (0.01, 0.1, 0.3, 1.0, and 3.0% by weight) have been synthesized to figure out its influence on their dielectric properties. The complex dielectric permittivity e* = e′−ie″ as function of frequency and temperature as well as polarisation loops P( E ) have been studied as a function of Mn concentration. It was found that Mn doping is restrained the Vogel-Fulcher law held in the unmodified PLZT compound producing essential change of the dependence of e* on temperature and frequency and of the shape of P( E ). The observed effects are explained by gradual involvement of Debye and Maxwell-Wagner polarisation mechanisms in relaxation processes with the growth of the concentration of Mn concentration admixture. A decrease of the e'( T ) maximum value and shift of the maximum to higher temperatures is observed. The observed effects are attributed to impacts of Mn 2+ and Mn 3+ ions: formation of oxygen vacancies paired with Mn 2+ as dipoles and Jahn-Teller distortion prompted by Mn 3+ ions.