New approaches to preparing powder and ceramics of double perovskite Sr2AlNbO6 (SAN) are presented. In addition to the conventional solid-state method, we employed organic solvents, sol-gel synthesis and liquid precursor plasma spraying (LPPS) to deposit SAN ceramic layers. For these purposes, we used a niobium oxalate complex forming stable solutions or gels in DMF with Sr2+ and Al3+ nitrates. We investigated the composition and thermal behavior of solutions, gels and prepared SAN samples and found that DMSO containing Nb precursor yields a stable impurity phase Sr4Al6O12(SO4) inside the final SAN powder. The measured linear thermal expansion coefficient (TEC) of sintered SAN is 12.4 & times; 10-6 K-1 at 1000 degrees C, which exceeds that for yttriastabilized zirconia, YSZ (11 & times; 10-6 K-1). The LPPS SAN coating contains two phases, identified as SAN and an amorphous oxide. The Young's modulus and Vickers nanohardness of SAN in LPPS-coating are also better than those of YSZ coating deposited with conventional atmospheric plasma spraying (APS).

The T-x phase diagram of the Na2MoO4-Li2MoO4 system was revised and two compounds, Na7Li(M & ocy;O4)4 (exists above 435 degrees C) and Na3-xLi1+x(MoO4)2 (0 <= x <= 0.2) were found, which melt incongruently at 544 and 515 degrees C, respectively. Orthorhombic Na7Li(M & ocy;O4)4 of a new structure type contains the [Li(MoO4)4]7- clusters of the central LiO4 tetrahedron sharing vertices with four MoO4 tetrahedra; the clusters are connected through NaO6 and NaO5 polyhedra in two types of layers, which alternate along the c axis. In monoclinic Na2.82Li1.18(MoO4)2, isostructural with Na3Li(MoO4)2, the trigonal bipyramids of NaO5 and (Na, Li)O5 share edges to form six- membered ribbons arranged along (101) in parquet-like layers resembling cuspidine-like layers with four- membered ribbons in Na7Li(M & ocy;O4)4. The layers in Na 2.82 Li 1.18 (MoO 4 ) 2 are connected by the MoO4 and LiO4 tetrahedra into a 3D framework. Under metastable crystallization conditions, the spinel-type Li2MoO4(sp) crystals were also obtained and structurally studied. Calculations of bond-valence-based energy barriers for potential diffusion of the lithium and sodium ions show probable 1D sodium-ion conductivity for Na7Li(M & ocy;O4)4. Possible 3D lithium-ion transport pathway in Li2MoO4(sp) passes through common triangular faces surrounding Li in octahedral 16d position and empty tetrahedral 8b site.

A 60-year-old problem with the atomic arrangements and exact compositions of alkali polytungstates related to hexagonal tungsten bronze (HTB) was solved. The systems A2WO4-WO3 (A = K, Rb) were restudied and the average monoclinic layered structures of stoichiometric polytungstates A4W11O35 (A = K, Rb, Cs, Tl) and A2W7O22 (A = K, Rb, Cs) were first successfully determined. The structures resemble those of "MoW11O36" and "MoW14O45" (J. Graham and A. D. Wadsley, Acta Crystallogr., 1961, 14, 379-383) and are derived from HTB by breaking into slabs parallel to (100) due to the ordered omission of some [WO]∞ chains along the hexagonal tunnels. The slabs in A4W11O35 (A = Cs, Tl) and A2W7O22 (A = Rb, Cs) are mutually shifted by the a/2 HTB unit cell axis. These data mainly confirmed our preliminary structural models of HTB-like alkali polytungstates (S. F. Solodovnikov, N. V. Ivannikova, Z. A. Solodovnikova and E. S. Zolotova, Inorg. Mater., 1998, 34, 845-853) and revealed a new similar thallium polytungstate. The structures of the HTB-like polytungstates and related compounds form a homologous series of layered complex oxides or fluorides An+2-xM3n+2X9n+8 where n = 2, 3 and 4 are equal to the numbers of HTB hexagonal tunnels across the polytungstate slab width for Tl2W4O13, A4W11O35 and A2W7O22 (A = K, Rb, Cs or Tl), respectively. The structures of the HTB-like polytungstates seem to intergrow with HTB-type AxWO3 to form, in particular, higher homologues of the series. Our group-supergroup analysis, measurements of nonlinear optical activity and electrical conductivity, and calculations of the bond-valence site energy barriers indicate possible ferroelectric/ferroelastic properties and moderate 2D oxide-ion mobility within the HTB-type slabs of the studied polytungstates.

The phase formation in the Na 2 MoO 4 -Cs 2 MoO 4 -NiMoO 4 system is studied using the solid-state synthesis and flux crystallization. The formation of a cesium-containing solid solution based on double molybdate Na 4-2 x Ni 1+ x (MoO 4 ) 3 of the alluaudite type and new triple molybdate of a related structure is established. Their structures contain layers of МоО 4 tetrahedra and coupled (Ni, Na)O 6 octahedra bridged by МоО 4 tetrahedra into three-dimensional open frameworks with tunnels along the c axis filled by sodium cations. By the example of isostructural Na 3.39 Ni 1.31 (MoO 4 ) 3 (I) and Na 3.18 Cs 0.29 Ni 1.26 (MoO 4 ) 3 (II), it is shown that in the alluaudite-type solid solution, cesium ions partially replace sodium cations in the framework tunnels, which provides the sodium ion conductivity. The structure of triple molybdate Na 2.64 Cs 0.64 Ni 1.36 (MoO 4 ) 3 (III) is a new type of the alluaudite superstructure deformed and tripled in volume. Its formation is caused by a significant differentiation of cations at (Ni, Na) and (Na, Cs) positions. In terms of the degree of deformation, this structure is intermediate between alluaudite and (pseudo)orthorhombic Na 10 Cs 4 M 5 (MoO 4 ) 12 ( M = Mn, Co) and Na 25 Cs 8 R 5 (MoO 4 ) 24 ( R = Fe, Sc, In). Among the crystallization products in the Na 2 MoO 4 -Cs 2 MoO 4 -NiMoO 4 system, crystals with a similar incommensurate modulation of the alluaudite structure along the c axis are found. Calculations of bond valence sum maps for sodium ions in the structures of I–III confirm the possibility of the one-dimensional sodium-ion conductivity for them at its lowest threshold for double molybdate for which the two-dimensional transport is also probable at elevated temperatures.

С помощью твердофазного синтеза и раствор-расплавной кристаллизации изучено фазообразование в системе Na2MoO4-Cs2MoO4-NiMoO4, установлено образование цезийсодержащего твердого раствора на основе двойного молибдата Na4-2xNi1+x(MoO4)3 типа аллюодита и нового тройного молибдата родственного строения. Их структуры содержат слои МоО4-тетраэдров и спаренных октаэдров (Ni, Na)O6, которые связаны мостиковыми МоО4-тетраэдрами в трехмерные ажурные каркасы с туннелями вдоль оси c, заполненными катионами натрия. На примере изоструктурных Na3.39Ni1.31(MoO4)3 (I) и Na3.18Cs0.29Ni1.26(MoO4)3 (II) показано, что ионы цезия в твердом растворе типа аллюодита частично замещают катионы натрия в туннелях каркаса, которые обеспечивают натрий-ионную проводимость. Структура тройного молибдата Na2.64Cs0.64Ni1.36(MoO4)3 (III) является новым типом деформированной и утроенной по объему сверхструктуры аллюодита, образование которой вызвано значительной дифференциацией катионов в позициях (Ni, Na) и (Na, Cs). Эта структура по степени деформации занимает промежуточное положение между аллюодитом и (псевдо)ромбическими Na10Cs4M5(MoO4)12 (M = Mn, Co) и Na25Cs8R5(MoO4)24 (R = Fe, Sc, In). Среди продуктов кристаллизации в системе Na2MoO4-Cs2MoO4-NiMoO4 найдены кристаллы с аналогичной несоразмерной модуляцией структуры аллюодита вдоль оси c. Расчеты карт сумм валентных усилий для ионов натрия в структурах I–III подтвердили для них возможность одномерной натрий-ионной проводимости при наиболее низком ее пороге у двойного молибдата, для которого при повышенных температурах вероятен и двухмерный транспорт.

Министерство науки и высшего образования Российской Федерации Российское химическое общество им.Д.И.Менделеева Секция по химической термодинамике и термохимии Научного совета РАН по физической химии Сибирское Отделение Российской Академии Наук Институт неорганической химии им.А.В.Николаева СО РАН

Forest typology holds the central position in modern forestry.We give an overview of research on forest typology in Russia.Forest typology in Russia actively developed and improved with respect to requests forestry throughout the entire period of its existence.It remains the necessary basis for preserving the biodiversity of land ecosystems and ensuring sustainable forest management amid the growing anthropogenic impact and climate change.The birth of scientific forest typology is associated with the name of G.F. Morozov.A biogeocoenotic approach to forest classification was offered by V.N.Sukachev.V.N.Sukachev developed classifications for boreal forests which had been little affected by economic activity.The biogeocoenotic approach proved effective there.However, when literally applied to commercial forests, the biogeocoenotic approach sometimes failed to deliver satisfying results.The exponential shrinkage of natural forests and the increasing share of dynamic secondary growth brought about the need to reflect the time-related forest changes in classifications.The origins of the genetic approach can be found in the writings of G.F. Morozov.The first satisfactory geo-genetic forest classification was built by B.A. Ivashkevich.B.P. Kolesnikov provided the theoretical grounding and main postulates for the approach.According to B.P. Kolesnikov, a geographical and genetic classification means a classification based on the forest origin and evolution patterns which takes account of all the forest ecosystem stages and can be used to predict their future changes.Currently forest typology develops as an interdisciplinary science.It integrates forestry, geobotanics, forest taxation, soil sciences, biogeography, geology, and landscape ecology.A new methodology is being developed.It is a synthesis of forest ecology and synergetic.It uncovers new reserves for the forest science development.

An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

New key data were obtained to solve old problems with the compositions and structures of the polytungstates related to the hexagonal tungsten bronze (HTB). The systems A2WO4-WO3 (A = K, Rb) were restudied and formation of K2W2O7, A2W3O10, K2W4O13, A4W11O35, and A2W7O22 was confirmed. The average monoclinic layered structures of A4W11O35 (A = K, Rb, Cs, Tl) and A2W7O22 (A = K, Rb, Cs) resembling those of “MoW11O36” and “MoW14O45” (Graham & Wadsley, 1961) were first solved. The structures are derived from the HTB by breaking into slabs parallel to (100) due to ordered omission of some [WO]µ chains along to hexagonal tunnels. The slabs in A4W11O35 (A = Cs, Tl) and A2W7O22 (A = Rb, Cs) are mutually shifted by the a/2 HTB unit cell axis. These data mainly confirmed our preliminary structure models of the HTB-like alkali polytungstates and revealed a new similar thallium polytungstate. The structures of the HTB-like polytungstates and related compounds forms the homologous series of layered complex oxides or fluorides An+2-xM3n+2X9n+8 where n = 2, 3 and 4 are equal to the numbers of the HTB hexagonal tunnels across the polytungstate slab width for Tl2W4O13, A4W11O35 and A2W7O22 (A = K, Rb, Cs or Tl), respectively. The structures of the HTB-like polytungstates seem to be able intergrowing with the HTB-type AxWO3 to form, in particular, higher homologues of the series. Our group-supergroup analysis, measurements of nonlinear optical activity, electrical conductivity and calculations of the bond-valence site energy barriers indicate possible ferroelectric/ferroelastic properties and moderate oxide-ion mobility within the HTB-type slabs of the studied polytungstates.

The work reviews the structure, non-stoichiometry, and ionic mobility of molybdates, tungstates, and other compounds crystallizing in the structure type of alluaudite (Na, Ca)(Fe, Mn, Mg)3(PO4)3 with the general Moore′s crystal chemical formula X(2)X(1)M(1)M(2)2(TO4)3, where X are large cations Na+, Ca2+, K+, Pb2+, etc., with the coordination number 8; M are octahedral cations, T = P, As, V, S, Mo, W. Using this formula and the corresponding site occupancies, possible limits of double molybdate and tungstate compositions of the alluaudite family are determined. Various types of distortions (superstructures) of alluaudite are considered; several groups of phases with different symmetries, numbers of anions in the unit cell, and vector relations with the unit cell of the original alluaudite structure are distinguished. It is shown that chains of partially defective positions X(2) and X(1) aligned along axis c play a key role in the transport of sodium cations in the alluaudite type phases. Phosphates and sulfates with alluaudite structure exhibit mainly 1D transport of sodium ions; however, calculations of the bond-valence sum maps, NMR data, and ab initio calculations show that 2D transport in the (100) plane is possible in complex molybdates and tungstates due to the transport of Na+ ions between X(2)–X(2) and X(1)–X(1) channels through the bridging site M(1). It is shown that the family of alluaudite-related (pseudo)orthorhombic triple molybdates Na10Cs4M5(MoO4)12 (M = Mn, Co) and Na25Cs8R5(MoO4)24 (R = Fe, Sc, In) also exhibits 2D diffusion of sodium ions via successive zigzag ion hoppings and that 3D transport may appear at elevated temperatures.

Рассмотрены особенности строения, нестехиометрия и ионная подвижность молибдатов, вольфраматов и других соединений, кристаллизующихся в структурном типе аллюодита (Na, Ca)(Fe, Mn, Mg)3(PO4)3 с общей кристаллохимической формулой по П. Муру X(2)X(1)M(1)M(2)2(TO4)3, где X — крупные катионы Na+, Ca2+, K+, Pb2+ и др. с КЧ = 8; M — октаэдрические катионы, T = P, As, V, S, Mo, W. На основе этой формулы и заселенностей соответствующих позиций выведены возможные пределы составов двойных молибдатов и вольфраматов типа аллюодита. Рассмотрены виды искажения (сверхструктуры) аллюодита, выделено несколько групп фаз, различающихся симметрией, числом анионов в ячейке и векторной связью с ячейкой исходной структуры аллюодита. Показано, что ключевую роль в переносе катионов натрия в фазах типа аллюодита играют цепочки частично дефектных позиций X(2) и X(1), идущие вдоль оси c. Для фосфатов и сульфатов со структурой аллюодита характерен преимущественно одномерный транспорт ионов натрия, однако, согласно данным расчетов карт сумм валентных усилий, ЯМР спектроскопии и ab initio расчетов, в сложных молибдатах и вольфраматах есть возможность двухмерной проводимости в плоскости (100) за счет перетока ионов Na+ между каналами X(2)—X(2) и X(1)—X(1) через мостиковую позицию M(1). Показано, что в семействе родственных аллюодиту (псевдо)ромбических тройных молибдатов Na10Cs4M5(MoO4)12 (M = Mn, Co) и Na25Cs8R5(MoO4)24 (R = Fe, Sc, In) также возможна двухмерная диффузия ионов натрия через последовательные зигзагообразные ионные перескоки с вероятной реализацией трехмерного транспорта при повышенных температурах.

Research subject. The processing waste of the slag from the Sredneuralsk copper smelter (“SUMZ technical sand”) is a finely dispersed (particle size less than 0.05 mm) material, mechanically activated by crushing cast slag and containing high concentrations of copper, zinc and other chalcophilic elements. Fayalite and ferrous glass predominate in its phase composition.Materials and methods. An outdoor experiment to study the elemental migration from waste into the soilplant system was conducted on the territory of the Institute of Geology and Geochemistry, Ural Branch of RAS (southwestern part of the Ekaterinburg, Sverdlovsk region). The soil substrate was prepared from lime-neutralised ombrotrophic peat (pH 6.6) with the addition of “technical sand” of 5, 10 and 20% by weight. Lawn grass mixture was grown on trial plots (1 m2). The samples of lawn grass (without separation by species), together with the root part and peat, were collected after the growing season by the “envelope” method, dried at room temperature until constant weight, and powdered. The chemical analysis of the samples was performed at the “Geoanalitik” shared research facilities of the Institute of Geology and Geochemistry, Ural Branch of RAS. The analyses were performed by inductively coupled plasma massspectrometry using the NexION-300S ICP mass-spectrometer.Results. The mobilisation of elements from the “SUMZ technical sand” into ombrotrophic peat during the summer was investigated, the distribution of elements in the underground and aboveground parts of lawn grasses was demonstrated, and accumulation coefficients were calculated. The content of most elements in all soil substrates containing waste decreased by autumn, for example, 2–3 times for Zn, Cu, Co, S, As, Pb, and Mo. The aboveground part of lawn grass had a lower concentration of the elements considered as compared to the roots, the greatest difference was observed for Co, Cd, Cu, and W. The lawn grasses grown on soil substrates with the different ratios of “SUMZ technical sand” had lower coefficients of accumulation of heavy metals compared to plants grown on the peat. The coefficients of Na, Ba, Mo, As, Cd, and Pb decreased with an increase in the proportion of waste, and for Li and Rb increased.Conclusion. The results of the research contribute to the study of the migration of elements from non-ferrous metallurgical waste into soil and plant systems.

Composition, thermal stability, crystal structure, and flux crystallization features of double molybdates of alkali metals with zirconium or hafnium are considered. The homogeneity ranges and crystal structures of lyonsiterelated Li2+4xM1- x (MoO4)(3) (M = Zr, Hf) were revised. The alkaline polymolybdates being the decomposition products of the double molybdates are shown to be the optimal fluxes for their crystallization. The areas of the ternary systems A(2)O-MoO3-ZrO2 (A = Li, Na, K, Rb, Cs) suitable for obtaining crystals of the double molybdates are outlined. The crystal structures of K2Mo2O7, K2Mo3O10 and Rb2Mo3O10 obtained as by-products in runs on crystallization of the double molybdates were refined to update the data of previous works. The electrical conductivity of A(2)Mo(2)O(7) and A(2)Mo(3)O(10) (A = K, Rb, Cs) was measured and it was found that its highest values are achieved for Cs2Mo2O7 (sigma = 1.2.10(-4) S/cm at 460 degrees C). The electrical conductivity in the isostructural series A(2)Mo(3)O(10) (A = K, Rb, Cs) increases from potassium trimolybdate to cesium trimolybdate and reaches sigma = 3.1.10(-5) S/cm at 460 degrees C for the latter. As a result, it was suggested that ionic conductivity of these polymolybdates is caused by the transfer of oxide ions. This was confirmed with our calculations of the bond valence based energy (BVE) landscapes for oxygen anions in the structures of A(2)Mo(2)O(7) and A(2)Mo(3)O(10) (A = K, Rb, Cs), which show predominantly one-dimensional oxide-ion diffusion along the chains formed of molybdenumcentered polyhedra.

The triple molybdates K3-xNa1+xM4(MoO4)6 (M = Ni, Mg, Co) and K3+xLi1-xMg4(MoO4)6 were found upon studying the corresponding ternary molybdate systems, and their structures, thermal stability and electrical conductiviplusmnty were investigated. The compounds crystallize in the space group R3c and are isostructural with the sodium-ion conductor II-Na3Fe2(AsO4)3 and yurmarinite, Na7(Fe3+, Mg, Cu)4(AsO4)6; their basic structural units are flat polyhedral clusters of the central M1O6 octahedron sharing edges with three surrounding M2O6 octahedra, which combine with single NaO6 octahedra and bridging MoO4 tetrahedra to form open three-dimensional (3D) frameworks where the cavities are partially occupied by disordered potassium (sodium) ions. The split alkali-ion positions in K3-xNa1+xM4(MoO4)6 (M = Ni, Mg, Co) give their structural formulae as [(K,Na)0.5□0.5)]6(Na)[M1][M2]3(MoO4)6, whereas the lithium-containing compound (K0.5□0.5)6(Mg0.89K0.11)(Li0.89Mg0.11)Mg3(MoO4)6 shows an unexpected (Mg, K) isomorphism, which is similar to (Mn, K) and (Co, K) substitutions in isostructural K3+xLi1-xM4(MoO4)6 (M = Mn, Co). The crystal chemistry of the title compounds and related arsenates, phosphates and molybdates was considered, and the connections of the cationic distributions with potential 3D ionic conductivity were shown by means of calculating the bond valence sum (BVS) maps for the Na+, Li+ and K+ ions. Electrical conductivity measurements gave relatively low values for the triple molybdates [σ = 4.8 × 10-6 S cm-1 at 390°C for K3NaCo4(MoO4)6 and 5 × 10-7 S cm-1 at 400°C for K3LiMg4(MoO4)6] compared with II-Na3Fe2(AsO4)3 (σ = 8.3 × 10-4 S cm-1 at 300°C). This may be explained by a low concentration of sodium or lithium ions and the blocking of their transport by large potassium ions.

An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research subject. In this paper, we investigate the possibility of recycling wastes from copper smelting facilities in brown mountain forest soils. The research object was “technical sand” obtained at the Sredneuralsky copper smelter as a byproduct. This finely dispersed material rich in copper, zinc and other chalcophilic elements undergo mechanical activation during crushing of the cast slag.Materials and methods. Experiments were carried out in the southern taiga district of the Trans-Ural hilly-foothill province (Middle Urals) in autumn before snow cover. Two types of forest areas identified according to the genetic forest typology were investigated: cowberry shrub pine forest and berry pine forest with linden, both under trees and in clear-cutting areas. The experiments involved scattering 1kg of waste across 1m2 of experimental soil, packing such a sand in 100 g packages made of non-woven material and burying these packages in 3 experimental plots a depth of 7–10 cm. Following 2 years, the packages were retrieved and weighed. The microelement analysis of soil samples was carried out by the method of inductively coupled plasma mass-spectrometry using an Elan-9000 ICP mass-spectrometer at the Geoanalitik center of the Institute of Geology and Geochemistry, Ural Branch of RAS.Results. It was found that, after 2 years of residing in the soil, copper smelting waste slag loses 11% of its mass. The majority of chalcophilic elements are involved in the biogeochemical cycle. The content of zinc, arsenic, cadmium and selenium varies most signfificantly. A difference in the degree of element migration from the “technical sand” to the brown mountain forest soil was observed for 2 forest types and clear-cutting areas. A single surface application of mineral waste (1 kg/m2 ) in autumn did not affect the qualitative composition of the grassy layer of all forest types and clear-cutting areas in the following spring–summer period.Conclusion. The findings can be of interest for specialists developing new methods for recycling mineral wastes from copper smelters. Future research should analyse the distribution of components migrating from the “technical sand” along the soil profile of forest soils, as well as their involvement in biogeochemical cycles.

An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Study of phase formation in the system K2MoO4-Na2MoO4 at 500 degrees C showed the existence of the only double molybdate K2-xNax-MoO4 (0.4 <= x <= 1) of the glaserite-related type. Using these data, the subsolidus phase relations in the systems K2MoO4-Na2MoO4-MMoO4 (M = Mn, Zn) were studied at 470-560 degrees C and the extended solid solutions based on the alluaudite-type Na4-2xM1+xMoO4)(3) were found. In the structure of K1.71Na1.71Mn1.29(MoO4)(3) (sp. gr. C-2/c, Z= 4, a = 13.0595(3) angstrom, b = 13.7892(3) angstrom, c = 7.2973(2) angstrom, beta = 111.339(1)degrees , R = 0.0134), the potassium ions partially replace Na+ in the channels running along c-axis. The structure of K1.84Na2.11Zn1.02(MoO4)(3) (sp. gr. P (1) over bar, Z = 2, a = 7.3258(8) angstrom, b = 9.4128(10) angstrom, c = 9.4302(10) angstrom, alpha = 93.104(3)degrees, beta = 104.573(3), gamma = 104.432(3), R = 0.0220) is isotypic with alluaudite-related aK(4)Zn(MoO4)(3) and seems to be a result of stabilizing an unknown triclinic modification of K4Zn(MoO4)(3) by substitution of sodium for potassium with the strong differentiation of alkali and zinc cations in the structure. In the structure of K1.5Na0.5Mn2(MoO4)(3) (sp. gr. Pcca, Z = 8, a = 10.6160(7) angstrom, b = 12.2714(8) angstrom, c = 18.0275(11) angstrom, R = 0.0155) of the a-K2Mn2(MoO4)(3) type, one of three initial potassium positions is jointly occupied by (Na, Mn); a similar phenomenon occurs in isostructural Rb3Na3Sc2(MoO4)(6). The structure contains zigzag-like ribbons of edge-sharing MnO6 octahedra linked with separate MnO6 octahedra and MoO4 tetrahedra into 3D containing channels along the c-axes filled by K+ ions. BVS maps show possible one-dimensional sodium-ion conductivity for the structures of K1.71Na1.71Mn1.29(MoO4)(3) and Rb3Na3Sc2(MoO4)(6).

Исследовано замещение молибдена на вольфрам в димолибдате цезия Cs2Mo2O7 с образованием твердого раствора α-Cs2Mo2–xWxO7 и найдено, что его область гомогенности при 540 °C достигает 0 ≤ x ≤ 0.6. Установлено, что объем моноклинной (псевдоромбической) элементарной ячейки и температура плавления твердого раствора монотонно возрастают с ростом содержания вольфрама, тогда как температура фазового перехода в ромбическую фазу практически неизменна и составляет около 390 °C. Получены кристаллы твердых растворов нескольких составов, определено их строение и найдено, что атомы вольфрама в основном локализованы в октаэдрических позициях структуры α-Cs2Mo2O7. Электропроводность Cs2Mo2O7 возрастает примерно на два порядка в результате фазового перехода при температуре 390 °C, достигая значения 1.2⋅10–4 См/см при 460 °C. Ввиду больших размеров ионов Cs+ и высокого заряда катионов молибдена предполагается, что переносчиком заряда являются анионы кислорода. Расчет карт сумм валентных усилий (СВУ) для возможных положений атомов кислорода в ячейке α-Cs2Mo2O7 показывает образование трехмерной системы каналов кислородной проводимости при значениях граничных изоповерхностей СВУ ≥ 2.13.