Tailored Synthesis of a Nonlinear Optical Phosphate with a Short Absorption Edge.

The nonlinear optical, polycrystalline Ba5P6O20 is prepared by sintering a stoichiometric mixture of BaCO3 and (NH4)2HPO4 (1050 K, 120 h); single crystals are grown by spontaneous crystallization from a Cs2O-P2O5 flux using Ba5P6O20, Cs2CO3, and (NH4)2HPO4 in a molar ratio of 2:3:8, resp.