Growth of new optical crystals from boron-containing fluxed melts

The reactivity of viscous melts has been analyzed as a function of the degree of anion polymerization. Precise techniques are proposed for detecting the phase relations and kinetics of high-temperature crystallization of new materials in four-to-six-component borate and tantalate systems. For rare earth polyfunctional borates RAl₃(BO₃)₄ (R = Y or lanthanides), efficient frequency conversion with parameters greatly exceeding the corresponding parameters for known media has been demonstrated for the first time. The conditions for fabrication of refractory optical single crystals having high thermal conductivity and other record characteristics (in comparison with the known diode-pumped lasers) for femtosecond integrated optics have been optimized. Bases of the laboratory technology of growth of such crystals are considered.