Comparing the freezing process and the spin-glass phenomenon of the nanopolarization based on the MnO additives PFW–PT relaxors

In this paper, pure and MnO added (1 − x)Pb(Fe2/3W1/3)O3–xPbTiO3 [(1 − x)PFW–xPT] ceramics are synthesized by using the conventional solid state oxide reaction method. The temperature dependence of the freezing processes is investigated by using the modified-Landau theory. This result is compared with the spin-glass phenomenon. According to the experimental data and the fitting results, the temperature-dependent local order parameters are derived from the modified-Landau theory and the spin-glass model with the experimental data separately and show similar tendencies. Furthermore, the derived local order parameters by using these two models show higher thermal stability by doping MnO additives and decreasing PbTiO3 contents. In conclusion, the ordering degree of B-site cations is enhanced by increasing PbTiO3 compositions and is reduced by doping MnO additives. This result is the main mechanism that induces the changes of the temperature-dependent local ordering parameters.