Magnetic properties of Bi$_{1-x}$Ca$_{x}$FeO$_{3-\delta}$ nanocrystals

Nanocrystalline magnetically ordered materials based on Ca-doped bismuth orthoferrite were synthesized by glycine-nitrate combustion method. The samples were characterized by X-ray diffractometry, helium pycnometry, Brunauer–Emmett–Teller method, scanning electron microscopy and elemental energy dispersive microanalysis. It was shown that all samples were isostructural to bismuth orthoferrite. The particles of nanopowders (with average particle size of about 0.3 $\mu$m) were composed of nanocrystals (with average crystallite size of about 40 nm). The difference between magnetic properties of Ca-doped samples and pure bismuth orthoferrite were demonstrated by Mössbauer spectroscopy and magnetometry. It was found that the samples contain nanocrystals with modified magnetic parameters and a small amount of fine fraction of other phases with a magnetic order.