Growth and characterization of acentric BaHf(BO3)2 and BaZr(BO3)2

Abstract Growth, single crystal X-ray diffraction, polarized Raman and infrared (IR) studies of BaHf(BO 3 ) 2 are presented. Raman and IR spectra of polycrystalline BaZr(BO 3 ) 2 are also reported to facilitate assignment of modes. BaHf(BO 3 ) 2 borate crystallizes in trigonal system, space group R 3 c , with lattice parameters: a =5.1540(4) A, c =33.901(3) A. It accommodates dolomite-like structure doubled in the c direction, which is built of alternating layers of HfO 6 octahedra and BaO 6 distorted trigonal prisms that are connected through borate groups. The obtained structural as well as spectroscopic data show that BaHf(BO 3 ) 2 is isostructural with BaZr(BO 3 ) 2 and the deviations from centrosymmetry is small.