ESR measurements have been carried out on Mn ions in PbTiO3 ceramics.
Mn ions in the PbTiO3 ceramics are incorporated at Ti4+ sites with mix
ed valence states of Mn2+ and Mn4+. The proportion of Mn2+ ions is the
highest for the calcined powder and changes during the firing process
. After the filing it decreases with increasing the firing temperature
in the range from 800 degrees C and 1100 degrees C, and increases at
temperatures above 1150 degrees C. Additionally, the proportion change
s with the amount of Mn ions. The proportion of Mn2+ decreases with in
creasing Mn dopants up to 0.20 wt%. In the range from 0.20 wt% and 0.2
5 wt% of MnO2 it increases steeply, and the Mn2+ and Mn4+ ratio is not
varied when more than 0.25 wt% MnO2 is doped. Piezoelectric propertie
s of Mn doped PbTiO3 can be explained by the changes of the valence st
ates of Mn ions.