Structural ordering and magnetic property of complex perovskite solid solution (1-x)Pb(Fe_2/3W_1/3)O₃ - xPb(Mg_1/2W_1/2)O₃

Pb(Fe_2/3W_1/3)O₃ was modified by doping Pb(Mg_1/2W_1/2)O₃ with Sol-Gel method using inorganic salts as precursors. At calcination temperature of 700°C, the resulted solid solution (1-x)Pb(Fe_2/3W_1/3)O₃ - xPb(Mg_1/2W_1/2)O₃ kept a perovskite structure in the whole doping range of 0≤x≤1. The obtained Pb(Mg_1/2W_1/2)O₃ (x=1) is fully ordered with a unit cell as two times as that of Pb(Fe_2/3W_1/3)O₃(x=0). Solid solution (1-x)Pb(Fe_2/3W_1/3)O₃ - xPb(Mg_1/2W_1/2)O₃ (0<x<1.0) also has an ordered crystal structure showing supperlattice peaks of 1/2 (111) and 1/2 (311) in X-ray diffraction, whose intensities become stronger as x increases. Combining electron diffraction and elemental analysis in transmission electron microscope, solid solution (1-x)Pb(Fe_2/3W_1/3)O₃ - xPb(Mg_1/2W_1/2)O₃ is verified as a single phase with perovskite structure, rather than a mixture of two phases. The particles of solid solution have a cubic morphology, and their grain size first decreases and then increases when doping coefficient x varies from 0.2 to 0.8. Due to the substitution of larger Mg²⁺ for smaller Fe³⁺ ions, its lattice constant increases linearly with the enhancement of x. According to the measured M-H curves, the magnetic performance of the solid solution decays as the doping coefficient x increases, because the formation of diamagnetic Pb(Mg_1/2W_1/2)O₃ could destroy the -Fe³⁺-W-O-W-Fe³⁺- and -Fe³⁺-O-Fe³⁺ - magnetic bonds in antiferromagnetic Pb(Fe_2/3W_1/3)O₃ phase.