Structural, magnetic, dielectric properties of multiferroic GaFeO3 prepared by solid state reaction and sol–gel methods

Polycrystalline GaFeO3 prepared by a solid state (SR) and a sol–gel (SG) procedure crystallize in the orthorhombic system with space group Pc21n. Neutron powder diffraction revealed iron ions fractions over the four sites Ga1, Ga2, Fe1 and Fe2: (0.2, 0.55, 0.70, 0.55) and (0.04, 0.75, 0.51, 0.72) for GaFeO3 (SR) and GaFeO3 (SG), respectively. The Curie temperature (TC) for GaFeO3 (SR) is about 190 K and increases to room temperature when the temperature of annealing is decreased from 1400 to 900 °C. The dielectric constant and dielectric loss are temperature and frequency independent for both samples. Below the transition temperature, TC, a ferrimagnetic order with a propagation vector k = 0 was derived from neutron powder diffraction data. The Fe3+ magnetic moments are ordered along the c-axis with a small component along a and b. At 3 K, the magnetic moments of Fe3+ are 3.47(9) and 4.40(1)μB for GaFeO3 (SR) and GaFeO3 (SG), respectively. Both, the cation and magnetic ordering depend strongly on the preparation conditions.