Investigation of the dielectric properties of MnO-additive Pb (Fe _2/3 W_1/3) -PbTi O₃ relaxors using the spin-glass model

The low-field dielectric responses of pure and 0.15 wt. % MnO-added (1-x) Pb (Fe23 W13) O3 -xPbTi O3 [(1-x) PFW-xPT] were investigated with the empirical model, the Curie-Weiss law and the spin-glass model. According to the experimental data and the fitting results, we conclude that (1) the lattice structure is changed and the electron compensation is induced with MnO addition. (2) The dielectric behaviors obey the Curie-Weiss law as the temperature is much far above Tm for all samples. (3) TCW, the temperature at which the dielectric behaviors deviate from the Curie-Weiss law, is higher and the diffuse phase characteristic is more obvious as decreasing PbTi O3 content or adding MnO. (4) The tailed temperature-dependent local order parameters, which are derived from the spin-glass model and the experimental results, for more diffuse phase transition relaxors show higher thermal stability in the spontaneous polarization microregions. (5) The temperature-dependent local ordering parameters change from a long-range-ordered ferroelectric state to a short-range-ordered relaxor with decreasing the PbTi O3 content or adding MnO.