Yu.A. Titov

Crystal structure of the high-pressure modification of NdTaO4

Abstract The crystal structure of the metastable NdTaO 4 high-pressure modification (HPM) has been studied by X-ray powder diffraction. It was found that the crystal structure of HPM NdTaO 4 belongs to the monoclinic LaTaO 4 -type structure (space group P2 1 /c , a =7.5920(7) A, b =5.4673(5) A, c =7.7022(7) A, β =100.032(6)°, Z =4). The difference in structure between LnTaO 4 with Ln=Nd–Lu (fergusonite-type structure) and that with Ln=La–Pr (monoclinic LaTaO 4 -type structure) is most likely due to the difference in size of the rare-earth cations.

Synthesis, structure and ferroelectric properties of heteroblock slab phases in La2Ti2O7–LaTaO4 system

Abstract The succession of phase transformations in the La 2 Ti 2 O 7 –LaTaO 4 system on heat treatment of the co-precipitated crystallized hydroxides has been studied. We have studied the possibility of the formation of a number of heteroblock polar slab phases La 4p+2 q Ti 4 p Ta 2 q O 14 p +8 q ( p =1, q =1, 2, 3, 5) having an ordered arrangement of alternating perovskite-type blocks of two and four BO 6 octahedron slabs. The crystal structure has been determined and the spontaneous polarization has been estimated.

Peculiarities of polymorphic transformations in YbTaO4 and crystal structure of its modifications

Abstract The succession of phase transformations upon YbTaO 4 synthesis from a mixture of co-precipitated hydroxides has been determined. Some peculiarities of the polymorphic transformations in YbTaO 4 ( M - and M I -fergusonite structure types) have been studied. Details of the crystal structure of the M - and M I -modifications of YbTaO 4 have been determined using X-ray powder diffraction.

Crystal structure of the high-pressure modification of LaNbO4

Abstract The crystal structure of the metastable LaNbO4 high-pressure modification (HPM) has been studied by X-ray powder diffraction. It was found that the crystal structure of HPM LaNbO4 belongs to- the room temperature BaMCF4 -type structure (space group Cmc21, a = 3,941(1)Å, b= 14,460(4) Å, c = 5,681(2) Å, Z = 4).

Mechanisms for the formation of layered A4B3O12 compounds from coprecipitated hydroxocarbonate and hydroxide systems

We have established and analyzed the sequences of phase transitions in synthesis of layered compounds in the AnBn–1O3n family (

Mechanisms for the formation of laminar titanates AIIn-4La4Tin-1O3n from coprecipitated component systems

{\text{A}}_3^{\text{II}}{\text{LnB}}_3^{\text{V}}{{\text{O}}_{{12}}}

Synthesis and luminescent investigation of the Sr 3 LaTa 3 O 12 layered perovskite

(AII = Ba, Sr, Ln = La, Nd, BV = Nb, Ta) and La4Ti3O12 with n = 4) from coprecipitated hydroxocarbonate and hydroxide systems, including steps involving the formation, solid-phase reaction, or structural rearrangement of intermediates.

Phase Transformations in Formation of Layered Perovskites from Coprecipitated Components

Abstract The succession of phase transformations with heat treatment of co-precipitated hydroxy-carbonates with the ratio Sr/La/Ta=2:1:3 has been established. The possibility has been shown to obtain Sr2LaTa3O11. It is the first representative of a series of slab perovskite-like compounds of the AnBnO3n+2-type with n=3. Sr2LaTa3O11 belongs to a new (own) structure type. The formation mechanism and the existence conditions have been investigated. Also the peculiarities of the Sr2LaTa3O11 slab perovskite-like structure have been determined.