CRYSTAL-GROWTH OF YVO4 USING THE LHPG TECHNIQUE

A laser heated pedestal growth (LHPG) technique utilizing a 50 W CO2 laser source was employed for the growth of YVO4. A growth method where only a small volume of the substance is melted was selected, since vanadium oxides vaporize readily at the melting point of YVO4 (1810-degrees-C). The feed and seed rods were prepared from ceramics made from different Y2O3-V2O5 compositions synthesized by both solid state and wet chemical methods. The congruent melting composition (CMC) was determined to be 49.3 mol% V2O5-50.7 mol% Y2O3. Two phases in addition to YVO4 were observed and found to be Y8V2O17 and a black crystalline YVO4-x (0 < x < 1) which can be deduced from the Y2O3-V2O5-V2O3 ternary phase diagram. The occurrence of these phases can be minimized by reducing the length of the float zone and using ceramic rods rich in V2O5.