J. Waliszewski

The Magnetic Properties of GaFeO_3 by Neutron Diffraction and Mössbauer Spectroscopy

The multiferroic GaFeO3 synthesized by a sol gel method and conventional solid state reaction show remarkably di erent magnetic transition temperatures. Both samples have orthorhombic crystal structure Pc21n. Results of a new analysis of neutron di raction and Mössbauer data are presented. Full agreement between parameters was achieved using the Mössbauer data as the constraints in the re nement of neutron di raction data at low and at high temperature. Magnetic moments are reported.

Magnetic and structural properties of Fe3−xCrxAl0.5Si0.5

Results of X-ray, neutron, magnetization and M?ssbauer measurements on polycrystalline samples of Fe3?xCrxAl0.5Si0.5 (x = 0, 0.125, 0.250, 0.375 and 0.5) alloys are presented. The alloys crystallize in the structure of DO3 type, and their unit cell volumes are practically independent of the chromium concentration. X-ray and neutron diffraction confirmed the phase homogeneity of all the samples. Neutron and Mossbauer measurements disclosed that Cr atoms occupy preferentially B-sites, while D sites are almost entirely occupied by Al and Si. The total magnetisation as well as the site and individual magnetic moments ?Fe(A,C), ?Fe(B) and ?Cr(B,D) have been found to be linearly dependent on the chromium concentration.

Phase composition and magnetism of sol–gel synthesized Ga–Fe–O nanograins

ABSTRACT We have succeeded in synthesizing orthorhombic Ga(1−x)Fe(1+x)O3 (−0.05 x0.5), hexagonal GayFe(2−y)O3 (0y1.8) and cubic Ga(1+z)Fe(2−z)O4 (−0.1z0.8) nanograins of gallium ferrites using conventional precursors and an organic environment of Pechini scenario under atmospheric-pressure conditions (SG method). Phase composition and homogeneity were analyzed using X-ray diffraction. Small angle neutron scattering disclosed ellipsoidal particle shapes of gallium iron oxides (GFO) crystallizing in orthorhombic (o-GFO) and hexagonal (h-GFO) symmetry and parallelepiped shapes of Ga(1+y)Fe(2−y)O4 (c-GFO) grains. Despite local agglomeration among the magnetic grains, the scanning electron microscopy and transmission electron microscopy images point to faced-elliptical shapes. The Mössbauer spectroscopy with magnetization measurements was carried out in the temperature range of 5–295 K. The analysis of gallium ferrites magnetism demonstrates that iron atoms locate with various probabilities in crystallographic positions and the spontaneous magnetization preserves up to room temperature (RT).