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The low-field dielectric responses of pure and 0.15wt.% MnO-added (1−x)Pb(Fe2∕3W1∕3)O3–xPbTiO3 [(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 PbTiO3 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 PbTiO3 content or adding MnO.

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Articles you may be interested inEvolution of structure, dielectric properties, and re-entrant relaxor behavior in Ba5LaxSm1−xTi3Nb7O30 (x=0.1, 0.25, 0.5) tungsten bronze ceramics Magnetic glassy behavior in ferroelectric relaxor type solid solutions: Magnetoelectric relaxor Polarization loop deformations of an oxygen deficient Pb ( Zr 0.25 , Ti 0.75 ) O 3 ferroelectric thin filmTwo different methods, the conventional direct oxide synthesized method and the two-step indirect synthesized ͑IS͒ method, were employed to synthesize the 0.75Pb͑Fe 2/3 W 1/3 ͒O 3 -0.25PbTiO 3 ceramics. The low-field dielectric responses were investigated using the empirical law and the Curie-Weiss law. The temperature-dependent local ordering parameters were derived from the experimental results using the spin-glass model and the modified-Landau theory separately. According to the experimental data and the fitting results, it is concluded that the temperature-dependent local order parameters are changed from a short-range-ordered relaxor to a long-range-ordered ferroelectric state using the IS method. On the basis of the physical concepts of the spin-glass model, the modified-Landau theory and the ordering models, it is suggested that local polarizations are affected not only by degree of ordering but also by space charge polarization. In contrast, the glassy behavior of local polarization is affected only by degree of ordering but has nothing to do with space charge polarization. It is because local fields induced by space charge polarization have the same effect on local polarizations and are neutralized when calculating the correlation between neighboring polar microregions. On the other hand, the freezing process of local polarizations is affected by both degree of ordering and space charge polarization because local polarization affected by local fields cannot be neutralized when calculating the individual behavior of local polarization.