Ternary composition of V2O3-MgO-SiO2

This patent describes a method of preparing a composition involving V2O3, MgO and SiO2 that is crystallized from a liquid with which the composition is in equilibrium on the liquidus surface and wherein the liquid has a composition that falls within a polygon shaped shaded area ABCDE as shown in the disclosed FIGURE for a ternary composition diagram of V2O3, MgO and SiO2. It comprises: heating V2O5 powder having a particle size of less than about 50 microns in an atmosphere in which the partial pressure of oxygen is in the range of 10-5 to 10-10 atmosphere while gradually increasing the temperature over a temperature range of about 600 degrees C. to 1300 degrees C. and holding the final temperature for a period to ensure complete reduction of all vanadium to V3+; heating MgO and SiO2 powders each having a particle size of less than about 50 microns for a period of about 10 to 14 hrs. at a temperature in the range of about 1000 degrees C to 1200 degrees C.; thoroughly grinding together an amount of V2O3 in the range of about 30 to about 98 wt %, with an amount of MgO, in the range of greater than 0 to about 50 wt %, and an amount of SiO2 in the range of greater than 0 to about 40 wt. % to produce a mixture having a grain size of less than about 50 microns, pelletizing the mixture, at a pressure of about 5,000 psi; heating the pellets at a temperature in the range of about 1400 degrees C to 1800 degrees C for a period in the range of about 12 to 48 hrs. in an atmosphere in which the partial pressure of oxygen is in the range of 10-10 to 10-15 atmosphere to produce a melt; and cooling the melt and crystallizing out the composition involving V2O3, MgO and SiO2, and separating the composition involving V2O3, MgO and SiO2 from the rest of the melt