Hardness and etching studies on flux grown YFeO/sub 3/ crystals

Results of Vicker's microhardness (H/sub v/), fracture toughness (K/sub c/), brittleness (B/sub i/), and dislocation etching characteristics on [110] and [001] planes of flux grown yttrium orthoferrite crystals are reported. The values of H/sub v/, K/sub c/, B/sub i/ are estimated to be 1235.08 Kg/mm/sup 2/, 0.1912 gm/ mu m/sup 3/2/, and 8.1955 mu m/sup -1/2/, respectively, for [110] plane, whereas for [001] plane the values of H/sub v/, K/sub c/, and B/sub i/ are 1027.12 kg/mm/sup 2/, 0.5975 gm/ mu m/sup 3/2/, and 1.875 mu m/sup -1/2/, respectively. The variation o H/sub v/ with applied load is explained to follow from the Hays and Kendalls law. Etching kinetics of YFeO/sub 3/ surfaces in H/sub 3/PO/sub 4/ at different temperatures leads to activation energy values for etch pits; the activation energies for dissolution parallel to [110] and [001] planes (i.e., lateral dissolution E/sub L/) are 0.41 eV and 0.34 eV, respectively. The activation energies for dissolution perpendicular to [110] and [001] planes (i.e., vertical dissolution E/sub D/) are 0.20 eV and 0.21 eV, respectively.<>