Synthesis, structure and characterization of a new nonlinear optical calcium borate [Ca2B5O9]·[H(OH)2]

A new nonlinear optical crystal [Ca2B5O9]·[H(OH)2]− built by B5O12 cluster units has been made under hydrothermal condition, which displays a SHG response of about 3.5 times that of KDP and is phase matchable, as well as has a high thermal stability up to 500 °C. Furthermore, the puc B-O net and hcb Ca-O net are further interpenetrated to form the final total Schläfli symbol of {412·63}.79