Crystal structure of La2MoO6 consists of La2O2 layers and MoO4 tetrahedra. It is similar in some aspects to that of high-temperature superconductor La2CuO4.

Several different types of tungstates and molybdates were studied. The most interesting of them are the rare-earth tungstates Ln₂WO₆ and molybdates Ln₂MoO₆, crystals A₂(WO₄)₃ (A = Al, Sc) and Dy₂(MoO₄) ₃.

The flux method was used to grow for the first time the series of Ln₂WO₆ and Ln₂MoO₆ single crystals and to refine their crystallographic characteristics, polymorphism, and physical properties. The structure of La₂WO₆ crystals is significantly different from that of other compounds of this group and is characterized by polytypism with ordered alternations of two types of layers of densely packed atoms stacked in the sequences of cacac (layer A) or cbcbc (layer B). The value of the c lattice parameter of these polytypes varies from 22.1 to 179.7 A.

A novel structure type was found also for BiLaWO₆ which can be considered as a transitional one between those of Ln₂WO₆ and Bi₂WO₆.

Single crystals of Al₂(WO₄)₃ and Dy₂(MoO₄)₃ were firstly grown and studied in our laboratory. The first of them undergo ferroelastic phase transition near -6^oC, can be readily doped with Cr and used as laser material. The Dy₂(MoO₄)₃ is an improper ferroelectric of the gadolinium molybdate family and has the Curie point of 140^oC.

1. Growth and basic properties of rare-earth and yttrium oxytungstate Ln₂WO₆ crystals.
   V.K.Yanovskii and V.I.Voronkova. Neorgan. Mater. , 1975, v.11, p.91.
2. Growth and basic properties of rare-earth and yttrium oxymolybdate Ln₂MoO₆ crystals.
   V.K.Yanovskii and V.I.Voronkova. Neorgan. Mater. , 1976, v.12, p. 140.
3. Growth of rare-earth oxytungstates Ln₂WO₆ from fluxed melts.
   V.I.Voronkova and V.K.Yanovskii. Kristallografiya, 1976, v.21, p.236.
4. Crystallography and properties of Ln₂WO₆ single crystals.
   V.K.Yanovskii and V.I.Voronkova. Kristallografiya, 1976, v.20, p. 579.
5. Polytypism of La₂WO₆ crystals.
   V.K.Yanovskii and V.I.Voronkova. Kristallografiya, 1981, v.26, p. 604.
6. Growth of beta-Ga₂O₃ and Al₂(WO₄)₃ crystals from sodium polytungstate flux.
   V.I.Voronkova, V.K.Yanovskii, and V.A.Koptsik. Vestnik Mosk. Univ., Fiz.,Astron. , 1968, v.23, p.109.
7. Growth and properties of Dy₂(MoO₄)₃ crystals.
   V.I.Voronkova, T.G.Kozinskaya, and V.K.Yanovskii. Kristallografiya, 1978, v.23, p. 865.