VALENCY STATES AND DISTRIBUTION OF MANGANESE IONS IN PZT CERAMICS SIMULTANEOUSLY DOPED WITH MN AND NB

EPR, X-ray spectral microanalysis, and dielectric investigations are performed on Pb [Mn0.02(Zr0.52Ti0.48)(1-0.02-x)Nb(x)]O3 solid solutions. Changes of Mn ion valency states and Mn ion distribution changes between grains and grain boundary layers as well as dielectric losses are studied as function of Nb content. It is shown that a rise of Nb content results in a successive lowering of Mn valency states (Mn4+ --> Mn3+ --> Mn2+). EPR spectra reveal the lowest concentration of Mn2+ and Mn4+ at n-degrees(Nb) almost-equal-to 0.0175 mol%. X-ray spectral microanalysis proves that for Nb content lower than n-degrees(Nb) Mn is concentrated mostly in grain boundary layers, for n(Nb) > n-degrees(Nb) diffusion of Mn ions into grains is observed. A jump in loss factor at n-degrees(Nb) is found; the origin of the jump is discussed.