Exploration of structural, thermal, vibrational and spectroscopic properties of new noncentrosymmetric double borate Rb3NdB6O12

Atuchin, V. V.; Subanakov, A. K.; Aleksandrovsky, A. S.; Bazarov, S. G.; Bazarova, J. G.; Dorzhieva, S. G.; Gavrilova, T. A.; Krylov, A. S.; Molokeev, M. S.; Oreshonkov, A. S.; Pugachev, A. M.; Tushinova, Yu. L.; Yelisseyev, A. P. ADVANCED POWDER TECHNOLOGY, 28 (5):1309-1315; Doi: 10.1016/j.apt.2017.02.019 MAY 2017

New noncentrosymmetric rare earth borate Rb₃NdB₆O₁₂ is found in the ternary system Rb₂O–Nd₂O₃–B₂O₃. The Rb₃NdB₆O₁₂ powder was fabricated by solid state synthesis at 1050 K for 72 h and the crystal structure was obtained by the Rietveld method. Rb₃NdB₆O₁₂ crystallized in space group R32 with unit cell parameters a = 13.5236(4), c = 31.162(1) Å, Z = 3. From DSC measurements, the reversible phase transition (I type) in Rb₃NdB₆O₁₂ is observed at 852–936 K. The 200 μm thick tablet is transparent over the spectral range of 0.3–6.5 μm and the band gap is found as E_g ∼ 6.29 eV. Nonlinear optical response of Rb₃NdB₆O₁₂ tested via SHG is estimated to be higher than that of K₃YB₆O₁₂. Blue shift of Nd luminescent lines is found in comparison with other borates. The vibrational parameters of Rb₃NdB₆O₁₂ are evaluated by experimental methods.