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In this study, we have investigated the effects of grain size on the structural and magnetic properties of La0.8Sr0.2MnO3 powder samples. The Williamson-Hall method was employed on the x-ray peak profile of these powder samples to determine the lattice microstrain. It was found that the microstrain increases by decreasing grain size. The magnetization decreases by decreasing grain size. A decrease in magnetization by decreasing grain size indicates formation of magnetically dead layer at the surface of grains. The thickness of such a magnetically dead layer increases by decreasing particle size. It seems that one of the sources for the formation of this magnetically dead surface layer is the microstrain. By subsequently annealing at a temperature of 800°C, the microstrain was released partially and magnetic properties were improved.

BixY3–xFe5O12 (x = 0.0, 0.9, 1, 1.1, 1.2, and 1.3) were synthesized by the sol–gel method to investigate the effect of Bi substitution on the structural and magnetic properties of YIG. The XRD results indicate that all the diffraction peaks belong to the pure phase. The Mössbauer analysis shows an increase in the Fetrue(dtrue)3+/Fetrue[atrue]3+ ratio and also a line broadening at tetrahedral sites, which suggests a relocation of yttrium ions at dodecahedral sites with iron ions at octahedral sites. The saturation magnetization fluctuates with increasing bismuth content, which has been explained based on Mössbauer results. The change in vibrational band broadening and the observation of a new band in the far‐FTIR spectra confirm the proposed cation relocation.

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