材料期刊网

Nanosized YMnO3 powders of grain size below 100 nm were prepared and characterized by various techniques to understand the size effect of the microstructures and the stoichiometry of the as-prepared powders. It is revealed that the grain surface oxidization state depends on grain size, with a lower oxidization state for the smaller grains. Raman and infrared spectroscopy studies show a remarkable broadening of the reflection peaks with decreasing grain size, identifying the significant surface structure relaxation effect for small-size powders. The ferromagnetic-antiferromagnetic transition around 65-68 degreesC is determined by the specific-heat measurement, also indicating the remarkable size dependence.