Olga M. Basovich

Formation laws for scheelite-like triple molybdates LiMLn2(MoO4)4

The size factor is shown to be decisive in the structure formation of triple molybdates LiMLn2(MoO4)4. The LiMLn2(MoO4)4 compounds (where M is a large alkali metal) are formed when 0.48 Å ≤ rM+ − rLn3+ ≤ 0.60 Å.

The double molybdate Na9Sc(MoO4)6 refined from powder XRD data.

Na9Sc(MoO4)6 {nonasodium scandium hexakis[tetraoxidomolybdate(II)]} was synthesised by a solid-state method. The basic structure units are polyhedral clusters composed of an ScO6 octahedron and three NaO6 octahedra sharing total edges. The clusters are connected by sharing vertices with bridging MoO4 tetrahedra, forming a three-dimensional framework where the cavities are occupied by the other two crystallographically independent Na atoms.

Spectral-luminescent properties of LiRbLa2 − x Eu x (MoO4)4 solid solutions

The luminescent properties of LiRbLa2 − xEux(MoO4)4 (x = 0.002, 0.02, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0) solid solutions are investigated under laser excitation {λex = 337.1 nm). It is established that the composition containing 50 at % Eu3+ is the brightest of the considered set of phosphors and has the highest quantum yield.

Synthesis, crystal structure and properties of alluaudite-like triple molybdate Na{sub 25}Cs{sub 8}Fe{sub 5}(MoO{sub 4}){sub 24}

A new triple molybdate Na25Cs8Fe5(MoO4)24 was synthesized using solid state reactions and studied with X-ray powder diffraction, second harmonic generation (SHG) technique, differential scanning calorimetry, Mossbauer and dielectric impedance spectroscopy. Single crystals of Na25Cs8Fe5(MoO4)24 were obtained and its structure was solved (the space group P1¯, a=12.5814(5), b=13.8989(5), c=28.4386(9) A, α=90.108(2), β=90.064(2), γ=90.020(2)°, V=4973.0(3) A3, Z=2, R=0.0440). Characteristic features of the structure are polyhedral layers composed of pairs of edge-shared FeO6 and (Fe, Na)O6 octahedra, which are connected by bridging МоО4 tetrahedra. The layers share common vertices with bridging МоО4 tetrahedra to form an open 3D framework with the cavities occupied by the Cs+ and Na+ cations. The compound undergoes first-order phase transformation at 642 K and above this phase transition, electrical conductivity reaches 10−3–10−2 S cm−1. Thus, Na25Cs8Fe5(MoO4)24 may be considered as a promising compound for developing new materials with high ionic conductivity.

New double molybdate Na{sub 9}Fe(MoO{sub 4}){sub 6}: Synthesis, structure, properties

A new double molybdate Na9Fe(MoO4)6 was synthesized using solid state reactions and studied with X-ray powder diffraction, second harmonic generation (SHG) technique, differential scanning calorimetry, X-ray fluorescence analysis, Mossbauer and dielectric impedance spectroscopy. Single crystals of Na9Fe(MoO4)6 were obtained and its structure was solved (the space group R3, a¼14.8264(2), c ¼19.2402(3) A, V¼3662.79(9) A 3 , Z ¼6, R ¼0.0132). The structure is related to that of sodium ion

Spectral-luminescent properties of AgLa1 − xEux(MoO4)2 solid solutions

The luminescent properties of AgLa1 − xEux(MoO4)2 (x = 0.1, 0.2, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0) under laser excitation (λ = 337.1 nm) are studied. It is shown that, upon substitution of Eu3+ for La3+, the symmetry of luminescence centers does not vary. According to the X-ray diffraction data, all samples have scheelite-like structure; the pattern of variation in volumes of their unit cells counts in favor of the presence of a continuous series of solid solutions. It is found that an increase in the europium concentration in AgLa1 − xEux(MoO4)2 leads to an increase in the luminescence intensity with a maximum at x = 0.9.