Garnet melt viscosity, surface tension and drainage.

Good surface morphology and layer uniformity of LPE-grown films are favored by fast melt removal after growth. Three flux modifying oxides; MoO3, V2O5, and WO3 are compared with respect of viscosity, surface tension and melt drainage. The viscosities and drainage times of V2O5 and MoO3 modified melts were smaller than those of WO3 modified melts. The beneficial effects on melt drainage observed with V2O5 additions are not the result of lower viscosities per se but originate in the reduced amount of supercooling required. The liquid-gas surface tension was found to be temperature independent. The drainage process was strongly temperature dependent, 40 kcal/mole, and the viscosities of melts had activation energies of 11 to 15 kcal/mole. A simple model to account for the observation is suggested.