Bair G. Bazarov

The formation and structural parameters of new double molybdates RbLn(MoO4)2 (Ln = Pr, Nd, Sm, Eu)

The structures of double molybdates with general compositions ALn(MoO4)2 (A – alkaline metals, Cu or Tl) have been considered and compared. It has been shown that the ionic radii ratio RLn/RA is a key factor governing crystal symmetry. Different structure fields in ALn(MoO4)2 (A = Li+, Na+, K+, Cu+, Rb+, Ag+, Cs+, Tl+) molybdates have been defined as a function of element composition.

Structural field of K2Al2B2O7-family crystals

The known crystal structures of borate compounds with general composition AI 2MIII 2B2O7 (AI: Na, K, Cs, Rb) have been considered. The structures in space groups P63/m, P-31c, P321 and P21/c have been found depending on cation combination. Criterion k = (r(MIII)+r(B)+2r(O))/r(AI) has been formulated and it controls the formation of trigonal K2Al2B2O7 (KABO) type structure. The existence of noncentrosymmetric KABO-type borates is possible over the range of k = 2.7 – 2.06. This range is promising for searching new borate crystals and solid solutions with pronounced nonlinear optical properties.

Synthesis, structural and vibrational properties of rare-earth molybdates MNd(MoO 4 ) 2 (M=Rb, Tl) and TlPr(MoO 4 ) 2

Microcrystals of MNd(MoO<inf>4</inf>)<inf>2</inf> (M=Rb, Tl) and TlPr(MoO<inf>4</inf>)<inf>2</inf> have been formed with solid state synthesis by the same synthesis route. Final products have been studied by XRD and SEM. Vibrational properties have been evaluated with Raman spectroscopy. More than 20 narrow Raman lines were observed in the experimental spectrum of the microcrystals.

Synthesis, micromorphology and structural properties of rubidium neodymium molybdate, RbNd(MoO 4 ) 2

Rubidium neodymium molybdate, RbN(MoO<inf>4</inf>)<inf>2</inf> has been synthesized by solid state reaction at T = 350°−600°C for 50 h in air. Morphology of RbNd(MoO<inf>4</inf>)<inf>2</inf> micrograins has been observed with SEM. Phase purity of final product is confirmed with XRD analysis. Crystal structure related to KY(MoO<inf>4</inf>)<inf>2</inf>-type, space group Pbcn, is supposed by XRD pattern comparison.