Growth of MgGa₂O₄ Crystals by PbO-PbF₂-B₂O₃ Flux Method

Abstract

An attempt to grow crystals of MgGa2O^2- was made by slow cooling of Pb0-PbF2-132O^2- flux with varying B2O^2- amount, in which MgO and Ga2O^2- were dissolved as solutes. The growth was conducted by heating mixtures at 1200, 1100 or 1000° C for 10 hours followed by cooling to 500° C at a rate of 5° C/hr. Results obtained were summarized as follows:
( 1 ) When the soaking temperature was 1200° C, the optimum composition of mixture to grow the crystal was MgO (12 mol%)-Ga2O^2-(8 mol%)-Pb0(35 mol%)-PbF2(35 mol%)-B2O^2-(10 mol%). Crystals grown in PbO-PbF2 flux containing a proper quantity of B2O^2- were bigger, more colorless and more transparent than those grown in Pb0-PbF2 flux.
( 2 ) When the optimum composition was used, a tendency for the crystal to grow bigger was increased as the soaking temperature was raised.
( 3 ) A maximum weight of the crystal grown in the mixture of 50 g in weight was about 168 mg (about 5 mm in size). The crystals were basically octahedral form with {111} faces, colorless and transparent.
( 4 ) A density of crystals, picnometrically determined, was 5.32 g/cm3. This value was in good agreement with the one reported in a literature.