Two new isostructural compounds, M2Cd3B16O28 (M = Rb, Cs), have been synthesized by a high-temperature solid-state reaction for the first time. M2Cd3B16O28 (M = Rb, Cs) crystallize in the monoclinic space group C2/c, with a = 21.4856(10) angstrom, b = 7.6852(4) angstrom, c = 13.3694(8) angstrom, beta = 91.705(3)degrees, Z = 4 for Rb2Cd3B16O28 and a = 21.621(3) angstrom, b = 7.6820(11) angstrom, c = 13.4170(18) angstrom, beta = 91.068(8)degrees, Z = 4 for Cs2Cd3B16O28. The compounds crystallize with (B16O34)(infinity) double layers bridged by Cd2+ cations to form three dimensional (3D) structures. The M+ (M = Rb, Cs) cations reside in the tunnels of the (B16O34)(infinity) double layers. First-principle electronic structure calculations show that the calculated band gaps of M2Cd3B16O28 (M = Rb, Cs) are 4.67 and 4.71 eV, respectively, which are in good agreement with the experimental values estimated from UV/Vis/NIR absorption spectroscopy by using the Kubelka-Munk equation, and the observed absorption peak is assigned as a charge transfer from the O 2p state to the Cd 5s state.
Chinese Acad Sci, Xinjiang Tech Inst Phys & Chem, Xinjiang Key Lab Elect Informat Mat & Devices, Urumqi 830011, Peoples R China;Univ Chinese Acad Sci, Beijing 100039, Peoples R China
Dong Xiaoyu,Shi Yunjing,Zhou Zhongxiang,et al. M2Cd3B16O28 (M = Rb, Cs): Two Isostructural Alkali Cadmium Borates with a New Type of Borate Layer[J]. EUROPEAN JOURNAL OF INORGANIC CHEMISTRY,2013(2):203-207.