A. E. Lapshin

Crystal Structures of Na2ZnP2O7, K2ZnP2O7, and LiKZnP2O7 Phases in the M2O–ZnO–P2O5 Glass-Forming System (M = Li, Na, and K)

The crystal structures of Na2ZnP2O7 and K2ZnP2O7 are determined from X-ray powder diffraction data. The structure of LiKZnP2O7 is determined using a single-crystal sample. In the alkali zinc phosphates studied, the Zn2+ cation is coordinated by four oxygen atoms of the phosphate tetrahedra. In the first two compounds, the [ZnP2O7]2– anion has the form of a sheet consisting of Zn and P oxygen-containing tetrahedra that involves only five-membered rings. In the LiKZnP2O7 structure, the zinc phosphate anion of the same composition has the form of a three-dimensional skeleton with a three-dimensional system of channels. These channels are linked via six-membered, eight-membered, and ten-membered rings. The atomic coordinates and interatomic distances are reported.

Structure of dipotassium (nitrilo-κN-triacetato-κ3O,O'',O'''')oxoperoxovanadate(V)–water (1/2)

K 2 [V(C 6 H 6 NO 6 )O(O 2 )].2H 2 O, M r =401.28, orthorhombic, Pnam, a=7.597 (5), b=12.951 (3), c=13.131 (5) A, V=1291.9 (1) A 3 , Z=4, D x =2.06 g cm -3 , λ(Mo Kα)=0.71069 A, μ=14.4 cm -1 , F(000)=808, T=295 K, R=0.019 for 1820 unique reflections. Vanadium is surrounded by a sevenmembered coordinating pentagonal bipyramid formed by a tetradentate nitrilotriacetate ligand, a bidentate peroxo group and a vanadyl oxygen. The bipyramid is symmetrical relative to the mirror plane passing through the V atom, the apical O atoms, the equatorial N atom and the midpoint between the peroxo O atoms. The nitrilotriacetate ligand forms three glycinate rings with the V atom, one of which coincides with the mirror plane, the two others being symmetrical relative to the plane

Synthesis and crystal structure of strontium borate Sr4B14O25

The new compound Sr4B14O25 (4SrO · 7B2O3) corresponding to an oxide ratio of 4: 7 has been identified and synthesized in the SrO-B2O3 system. The crystal structure of the compound has been determined (space group Cmc21, a = 7.734(5) Å, b = 16.332(5) Å, c = 14.556(5) Å, Z = 4, 702 F(hkl), R = 0.078). The borate anions form a three-dimensional framework consisting of borate groups of two types: three-ring structures (2□, Δ) and BO3 triangles. Layers formed by 14-membered rings composed of boron-oxygen tetrahedra and triangles packed within the layer according to the herringbone pattern can be distinguished in the framework. The strontium atoms are located on the mirror symmetry planes between these layers. The compound is metastable and decomposes, on long-term storage, into strontium di- and metaborate.

Crystallization and thermochromism of annealed heterostructures containing titanium and tungsten oxide films

Crystalline phases in heterostructures containing titanium and tungsten oxide films are studied after step annealing in vacuum at temperatures between 500 and 750°C. The films are deposited on a silica glass substrate by dc reactive magnetron sputtering. It is found that crystalline phases in single layers and bilayer structures form in a different way. In the latter, crystallization is influenced by the order of layer arrangement on the substrate. Thermochromism in structures annealed in vacuum is due to the oxygen-deficient phase WO3 − x belonging to the hexagonal syngony. This phase intensely grows as the temperature rises from 650 to 750°C.

Synthesis and crystal structure of the low-temperature modification of lithium potassium zinc diphosphate LiKZnP2O7

A new polymorphic modification, α-LiKZnP2O7, has been synthesized, which is a low-temperature modification of the LiKZnP2O7 compound. The crystal structure is determined by the Rietveld method from the X-ray powder diffraction data. The compound crystallizes in the monoclinic system (space group Pc, a = 12.3621(3) Å, b = 5.0655(1) Å, c = 10.2365(3) Å, β = 90.88(1)°, Z = 2) and has a framework structure similar to that of the high-temperature β phase. The framework is formed by the diphosphate groups and the oxygen tetrahedra of the zinc and lithium atoms, which statistically uniformly occupy equivalent positions in the structure.

Crystal structure of the K2(Zn3P4O14) compound

Single crystals of potassium zinc phosphate, namely, K2(Zn3P4O14), are grown by crystallization of a glass of the related compound. The crystal structure of the compound is determined using single-crystal X-ray diffraction.

Investigation into the Properties of a New Precursor for Preparation of Tetragonal Zirconia

A finely crystalline tetragonal zirconia powder with a crystal size of less than 40 nm is synthesized from zirconium peroxide. The metastable tetragonal phase of zirconia contains ∼1–3% H2O, is stable up to approximately 500–600°C, and possesses a sufficient stability at room temperature. It is demonstrated that the temperatures of the formation of low-temperature phases and their structure and stability depend on the prehistory of the material and the reactants used. The irreversible phase transformation from metastable forms into stable forms is accompanied by changes in the structure and composition of the phases due to the liberation of impurities (OH–, H2O) stabilizing the metastable phases.

Composition and structure of copper oxide films synthesized by reactive magnetron sputtering with a hot target

The influence of the target operation mode on the chemical composition and crystalline structure of copper oxide films deposited onto a quartz glass substrate has been studied using Raman spectroscopy and X-ray phase analysis. The films have been synthesized in an Ar + O2 gaseous environment using two identical magnetrons, differing only by the method of target cooling.

Mixed alkali-zinc diphosphates: Synthesis, structure, and properties

A series of mixed alkali-zinc diphosphates in the form of poly- and single crystals have been synthesized. Their physical-chemical, structural, and thermal characteristics have been determined. The compounds Na2ZnP2O7 and K2ZnP2O7 have a layered structural type, whereas LiNaZnP2O7, LiKZnP2O7, NaKZnP2O7, Li12Zn4(P2O7)5, and K2Zn3(P2O7)2 have a framework structural type.

Structure and chemical composition of the new zeolite ISC -1 from the data of nanocluster modeling

The cluster analysis and modeling of self-assembly of the crystal structures of zeolites, i.e., zeolite RHO, paulingite PAU, and hypothetical zeolite ISC-1 separated as a local structure in the paulingite framework, have been performed. It has been established using the tiling method that the RHO, PAU, and ISC-1 frameworks contain two, seven, and five topological types of cavities, which are occupied by extraframework cations and/or water molecules. The zeolite structures have been described as ensembles of nanoclusters that represent local regions of the tetrahedral T framework and uniquely determine the topological features of the framework. The structure of the synthesized paulingite-Na,K,TEA (where TEA is tetraethylammonium) has been analyzed using X-ray powder diffraction. The chemical formula of the ISC-1 zeolite in the form Na14K24Al38Si202O480 · nH2O has been proposed from the data on the composition and structure of paulingite (minerals and synthetic phases).