Study of the Valence State of the Manganese Ions in PbTiO₃ Ceramics by Means of ESR

Abstract

ESR measurements have been carried out on Mn ions in PbTiO 3 ceramics. Mn ions in the PbTiO 3 ceramics are incorporated at Ti 4+ sites with mixed valence states of Mn 2+ and Mn 4+ . The proportion of Mn 2+ ions is the highest for the calcined powder and changes during the firing process. After the firing it decreases with increasing the firing temperature in the range from 800°C and 1100°C, and increases at temperatures above 1150°C. Additionally, the proportion changes with the amount of Mn ions. The proportion of Mn 2+ decreases with increasing Mn dopants up to 0.20 wt%. In the range from 0.20 wt% and 0.25 wt% of MnO 2 it increases steeply, and the Mn 2+ and Mn 4+ ratio is not varied when more than 0.25 wt% MnO 2 is doped. Piezoelectric properties of Mn doped PbTiO 3 can be explained by the changes of the valence states of Mn ions.