A new potassium rare earth oxyborate K_2La_2(BO_3)_2O

摘要

A series of potassium rare earth oxyborates, K_2La_2(BO_3)_2O (RE = La, Nd, Sm and Eu), have been synthesized. Single crystal of the first member of the series, K_2La_2(BO_3)_2O, has been grown by the flux method. Its structure, determined by single crystal X-ray diffraction, shows that it belongs to the monoclinic system, space group P2_1/c with unit cell parameters of a = 11.422(2) A, b = 6.6803(13) A, c=10.813(2)A, ? = 17.23(3)° and Z = 4. Optical transmission spectrum shows that the K_2La_2(BO_3)_2O crystal is highly transparent from 215 nm to 2750 nm.