Phase relations, thermal conductivity and elastic properties of ZrO and HfO polymorphs at high pressures and temperatures.

In the present study, - phase diagrams of ZrO and HfO for a wide pressure range of 0-150 GPa at 0-2500 K were calculated for the first time using density functional theory with the method of lattice dynamics within the quasi-harmonic approximation. We calculated - conditions for a full sequence of high-pressure transformations, 2/ → → → 6̄2, for both compounds. At low temperatures, these transformations for ZrO are obtained at 7.

Resolving old problems with layered polytungstates related to hexagonal tungsten bronze: phase formation, structures, crystal chemistry and some properties.

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 WO-WO ( = K, Rb) were restudied and the average monoclinic layered structures of stoichiometric polytungstates WO ( = K, Rb, Cs, Tl) and WO ( = K, Rb, Cs) were first successfully determined. The structures resemble those of "MoWO" and "MoWO" (J.

Triple molybdates KNaM(MoO) (M = Ni, Mg, Co) and KLiMg(MoO) isotypic with II-NaFe(AsO) and yurmarinite: synthesis, potassium disorder, crystal chemistry and ionic conductivity.

The triple molybdates KNaM(MoO) (M = Ni, Mg, Co) and KLiMg(MoO) 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-NaFe(AsO) and yurmarinite, Na(Fe, Mg, Cu)(AsO); their basic structural units are flat polyhedral clusters of the central M1O octahedron sharing edges with three surrounding M2O octahedra, which combine with single NaO octahedra and bridging MoO 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 KNaM(MoO) (M = Ni, Mg, Co) give their structural formulae as [(K,Na)□)](Na)[M1][M2](MoO), whereas the lithium-containing compound (K□)(MgK)(LiMg)Mg(MoO) shows an unexpected (Mg, K) isomorphism, which is similar to (Mn, K) and (Co, K) substitutions in isostructural KLiM(MoO) (M = Mn, Co).

RbAgSc(WO): a new glaserite-related structure type, rubidium disorder, ionic conductivity.

A new triple tungstate RbAgSc(WO) (0 ≤ x ≤ 0.15) synthesized by solid state reactions and spontaneous crystallization from melts presents a new structure type related to those of CsNaYb(MoO) and NaSrTa(PO). The title compound in centrosymmetric space group Cmcm contains dimers of two ScO octahedra sharing corners with three bridging WO tetrahedra.

New triple molybdate RbAgIn(MoO): synthesis, framework crystal structure and ion-transport behaviour.

A new triple molybdate, RbAgIn(MoO) (0 ≤ x ≤ 0.02), was found in the course of a study of the system RbMoO-AgMoO-In(MoO) and was synthesized as both powders and single crystals by solid-state reactions and spontaneous crystallization from melts. The structure of RbAgIn(MoO) (x ≉ 0.

Synthesis, crystal structures and properties of the new compounds KAg(XO) (X = Mo, W).

Two new isostructural compounds, namely heptapotassium silver tetrakis(tetraoxomolybdate), KAg(MoO) (0 ≤ x ≤ 0.4), and heptapotassium silver tetrakis(tetraoxotungstate), KAg(WO) (0 ≤ x ≤ 0.4), have been synthesized and found to crystallize in the polar space group P6mc (Z = 2) with the unit-cell dimensions a = 12.

CsLiZn(WO) and RbLiGa(MoO): different filled derivatives of the cation-deficient CsZn(MoO) structure.

Two new compounds, namely cubic tricaesium lithium dizinc tetrakis(tetraoxotungstate), CsLiZn(WO), and tetragonal trirubidium dilithium gallium tetrakis(tetraoxomolybdate), RbLiGa(MoO), belong to the structural family of CsZn(MoO) (space group I-43d, Z = 4), with a partially incomplete (Zn□) position. In CsLiZn(WO), this position is fully statistically occupied by (ZnLi), and in RbLiGa(MoO), the 2Li + Ga atoms are completely ordered in two distinct sites of the space group I-42d (Z = 4). In the same way, the crystallographically equivalent A cations (A = Cs, Rb) in CsZn(MoO), CsLiZn(WO) and isostructural ALiZn(MoO) and CsLiCo(MoO) are divided into two sites in RbLiGa(MoO), as in other isostructural ALiR(MoO) compounds (AR = TlAl, RbAl, CsAl, CsGa, CsFe).

Synthesis, Structural, Thermal, and Electronic Properties of Palmierite-Related Double Molybdate α-CsPb(MoO).

CsPb(MoO) crystals were prepared by crystallization from their own melt, and the crystal structure has been studied in detail. At 296 K, the molybdate crystallizes in the low-temperature α-form and has a monoclinic palmierite-related superstructure (space group C2/m, a = 2.13755(13) nm, b = 1.

Rubidium dimolybdate, Rb(2)Mo(2)O(7), and caesium dimolybdate, Cs(2)Mo(2)O(7).

The crystal structures of dirubidium heptaoxodimolybdate, Rb(2)Mo(2)O(7), and dicaesium heptaoxodimolybdate, Cs(2)Mo(2)O(7), in the space groups Ama2 and P2(1)/c, respectively, have been determined for the first time by single-crystal X-ray diffraction. The structures represent two novel structure types of monovalent ion dimolybdates, A(2)Mo(2)O(7) (A = alkaline elements, NH(4), Ag or Tl). In the structure of Rb(2)Mo(2)O(7), Mo atoms are on a twofold axis, on a mirror plane and in a general position.

New triple molybdates Cs3LiCo2(MoO4)4 and Rb3LiZn2(MoO4)4, filled derivatives of the Cs6Zn5(MoO4)8 type.

Two new isotypic triple molybdates, namely tricesium lithium dicobalt tetrakis(tetraoxomolybdate), Cs3LiCo2(MoO4)4, and trirubidium lithium dizinc tetrakis(tetraoxomolybdate), Rb3LiZn2(MoO4)4, crystallize in the non-centrosymmetric cubic space group I-43d and adopt the Cs6Zn5(MoO4)8 structure type. In the parent structure, the Zn positions have 5/6 occupancy, while they are fully occupied by statistically distributed M2+ and Li+ cations in the title compounds. In both structures, all corners of the (M(2/3)Li(1/3))O4 tetrahedra (M = Co and Zn), having point symmetry -4, are shared with the MoO4 tetrahedra, which lie on threefold axes and share corners with three (M,Li)O4 tetrahedra to form open mixed frameworks.

Preparation, structures, and redox and emission characteristics of the isothiocyanate complexes of hexarhenium(III) clusters [Re6(mu3-E)8(NCS)6]4- (E = S, Se).

Hexarhenium(III) complexes with terminal isothiocyanate ligands, [(n-C(4)H(9))(4)N](4)[Re(6)(mu(3)-S)(8)(NCS)(6)] (1) and (L)(4)[Re(6)(mu(3)-Se)(8)(NCS)(6)] (L(+) = PPN(+) (2a), (n-C(4)H(9))(4)N(+) (2b)), have been prepared by three different methods. Complex 1 was prepared by the reaction of [(n-C(4)H(9))(4)N](4)[Re(6)(mu(3)-S)(8)Cl(6)] with molten KSCN at 200 degrees C, while 2b was obtained by refluxing the chlorobenzene-DMF (2:1 v/v) solution of [Re(6)(mu(3)-Se)(8)(CH(3)CN)(6)](SbF(6))(2) and [(n-C(4)H(9))(4)N]SCN. The [Re(6)(mu(3)-Se)(8)(NCS)(6)](4)(-) anion was also obtained from a mixture of Cs(2)[Re(6)(mu(3)-Se)(8)Br(4)] and KSCN in C(2)H(5)OH by a mechanochemical activation at room temperature for 20 h and isolated as 2a.