Processing by mechanosynthesis and properties of piezoelectric Pb(Mg1/3Nb2/3)O3–PbTiO3 with different compositions

The processing of piezoelectric (1 - x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–PT) with x = 0.2, 0.3, 0.35 and 0.4 ceramics from powders synthesized by mechanochemical activation of precursors has been studied. Conventional sintering, sintering in PbO-rich atmospheres and hot pressing were explored, and factors controlling the microstructure development were identified. Ceramics with a range of grain sizes between 0.2 and 5 (mu)m were obtained by varying the PbO partial pressure and temperature. Ceramic samples have a high crystallographic quality, most probably associated with a high chemical homogeneity, which makes them suitable for fundamental studies. A series of ceramics with the same microstructure but different values of x was prepared for the analysis of the properties as a function of composition and, therefore, of crystalline structure. Dielectric permittivity and losses as a function of temperature and frequency, ferroelectric hysteresis loops, and piezoelectric coefficients and losses, never reported before for this system, were studied and discussed in relation to the crystalline structure, the domain configuration and its dynamics.