Synthesis, crystal structure and magnetic studies of ZnY2O4 oxide

Abstract

ZnY₂O₄ oxide is prepared by sol-gel method via nitrate-citrate route. Powder X-ray diffraction (XRD) study shows orthorhombic unit cell with lattice parameters: a = 10.8290 Ǻ, b = 7.4518 Ǻ, c = 6.0985 Ǻ, space group Pccn and Z=4. Average crystallite sizes determined by Scherrer relation are found to be ~26-59 nm showing the formation of nanopaticles in the oxide. On Rietveld refinement of the unit cell structure, the agreement factors are lowered to: R_p=97.02%, R_wp=95.91% and R_exp=0.23%. The selected bond lengths are: Y₂-O₁: 3.7389 Å, Y₁-O₂: 3.0492 Å, Y₂-O₃: 2.1847 Å and Zn-O₁: 1.4088 Å, Zn-O₂: 3.7035 Å, Zn-O₃: 2.2777 Å. Formation of hysteresis loop in the range from-7.0 kG to +7.0 kG indicates the soft ferromagnetic nature of ZnY₂O₄ at 300 K. Density functional theory (DFT) calculation shows the valence band (VB) is spread over the range ~-9.0 to 0.0 and comprises mainly of O 2p and Y 4p, 4d, 5s orbitals, and the conduction band (CB) in the range from ~0.0 to 3.0 eV and comprises mainly of Y 4s, 4p and 4d orbitals. Very low value of energy band gap ~0.011 eV indicates weak semiconducting nature of ZnY₂O₄.