Hardness and etching studies on flux grown YFeO3 crystals

Results of Vicker´s microhardness (H_v), fracture toughness (K_c), brittleness (B_i), and dislocation etching characteristics on (110) and (001) planes of flux grown yttrium orthoferrite crystals are reported. The values of H_v, K_c, B_i are estimated to be 1235.08 Kg/mm², 0.1912 gm/μm^3/2, and 8.1955 μm^-1/2, respectively, for (110) plane, whereas for (001) plane the values of H_v, K_c, and B_i are 1027.12 kg/mm², 0.5975 gm/μm^3/2, and 1.875 μm^-1/2, respectively. The variation o H_v with applied load is explained to follow from the Hays and Kendalls law. Etching kinetics of YFeO₃ surfaces in H₃PO₄ 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_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_D) are 0.20 eV and 0.21 eV, respectively