Abstract: The microstructure and the piezoelectric properties as well as the valency of Mn in
Pb[(Zr_0.52Ti_0.48)_0.95(Mn_1/3Nb_2/3)_0.05]O₃ (PMnN-PZT) ceramics sintered at different temperatures
from 1070℃ to 1280℃ were investigated by XRD, SEM, TEM, XPS. The experimental results suggest that grain sizes, tetragonality and k_p
of the ceramics increase with the increase of sintering temperature, and Q_m fluctuates with the increase of sintering temperature. The obtained results by X-ray
photoelectron spectrum and TEM suggest that there exist apparently the liquid phase of PbO and stoichiometric composition departure during the sintering.
Low temperature induces the existence of the Mn²⁺, producing more oxygen vacancies, and therefore the fluctuation of mechanical quality
factor (Q_m) with the sintering temperature occurs.

Key words: PMnN-PZT, sintering temperature, valency of Mn, oxygen vacancies