Ein Beitrag zur Kristallchemie der Alkali-Erdalkalimetall-Oxovanadate: Synthese und Struktur von K3CaV5O15/A Contribution to the Crystal Chemistry of Alkaline-Alkaline-Earth Oxovanadates: Synthesis and Structure of K3CaV5O15

1995 ◽  
Vol 50 (2) ◽  
pp. 243-246 ◽  
Author(s):  
F.-D. Martin ◽  
Hk. Miiller-Buschbaum

Single crystals of K3CaV5O15 have been prepared by crystallization from melts. The com pound shows a new structure type with orthorhombic symmetry, space group D2h21-Cmma, a = 25.953(5), b = 15.688(3), c = 7.804(4) Å, Z = 8. Typical features of K3CaV5O15 are isolated cyclic V4O12 and V6O18 groups of corner sharing VO4 tetrahedra.

1995 ◽  
Vol 50 (5) ◽  
pp. 703-706 ◽  
Author(s):  
S. Münchau ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of AgCdVO4 have been prepared in closed silver tubes using V2O5 as a flux. The light-orange crystals show orthorhombic symmetry, space group D162h-Pnma, a = 9.786(2), b = 6.994(1), c = 5.439(1) Å, Z = 4. The hitherto unknown AgCdVO4 is related to the Olivine structure but isotypic to Ag2CrO4 and NaCd4(VO4)3 respectively. The differences in crystal chemistry between the Olivine type, NaCd4(VO4)3 and AgCdVO4 are discussed.


1996 ◽  
Vol 51 (4) ◽  
pp. 477-480 ◽  
Author(s):  
O. Schrandt ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of KBaVO4(I) and KSrVO4(II) have been prepared by crystallization from V2O5 flux. The yellowish crystals show orthorhombic symmetry, space group D162h-Pnma with (I): a = 7.774(2), b = 5.899(1), c = 10.375(2) Å , (II): a = 7.400(2), b = 5.812(1), c -9.961(1), Z = 4. Both compounds show an ordered distribution of K+ and Ba2+ and Sr2+ respectively. The different sizes of the KO10 and BaO9 (SrO9) polyhedra are discussed with respect to those of the β-K2SO4 structure, considering the calculations of the Coulomb terms of lattice energy.


1995 ◽  
Vol 50 (8) ◽  
pp. 1146-1150 ◽  
Author(s):  
Anne Utzolino ◽  
Karsten Bluhm

Single crystals of the compounds MnFe(BO3)O (I) and MnAl0.5Y0.5(BO3)O (II), were obtained by a B2O3 flux technique. I crystallizes with orthorhombic symmetry, space group D162h -Pnma (Nr.62), a = 939.92; b = 319.41; c = 939.11 pm; Z = 4 and II with monoclinic symmetry, space group C52h-P21/n (Nr. 14). a = 325.6; b = 955.1; c = 929.2 pm; β = 90.70° ; Z = 4. I is isotypic to the mineral Warwickite, while II is a distorded variant of this structure. All metal ions are octahedrally coordinated. Both structures contain isolated, trigonal planar BO3 units and oxygen atoms that are not coordinated to boron.


1996 ◽  
Vol 51 (3) ◽  
pp. 447-449 ◽  
Author(s):  
O. Sedello ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of (Cu,Mn)3.66Mo3O12 have been prepared in sealed copper tubes. X-ray investiga­tions lead to orthorhombic symmetry, space group D2h16-Pnma, a = 5.1541(9), b = 10.788(2), c = 18.114(3)) Å , Z = 4. (Cu,Mn)3.66Mo3O12 is iso­typic to NaCo2.31Mo3O12 and (Cu,Co)3.75Mo3O12 with split positions for two of the metals.


1995 ◽  
Vol 50 (4) ◽  
pp. 681-683 ◽  
Author(s):  
G. Tams ◽  
Hk. Müller-Buschbaum ◽  
Ch. Lang

Single crystals of LiBa2Cu3O6 have been prepared by recrystallization from melts in a stream of dry Argon as well as by spontaneous CO2- LASER heating. It crystallizes with orthorhom bic symmetry, space group D232h - Fmmm, a = 8,219(2), b = 11,520 (2), c = 14,284(3) Å, Z = 8. The crystal structure is isotypic to NaBa2Cu3O6.


1996 ◽  
Vol 51 (2) ◽  
pp. 240-244
Author(s):  
Hk. Müller-Buschbaum ◽  
St. Gallinat

Abstract Single crystals of (I) CuDyMo2O8 and (II) CuYbMo2O8 have been prepared by crystalli­sation from melts. Both com pounds crystallize with orthorhombic symmetry, space group D152h-Pbca with (I): a = 10.195(1), b = 9.721(2), c = 14.563(3); (II): a = 10.094(6), b = 9.628(9), c = 14.467(8) Å, Z = 8. The crystal structure is characterized by a triangular CuO3-polygon, a square antiprismatic coordination around the Rare Earth ions and the typical Mo O4 tetra­ hedra.


1995 ◽  
Vol 50 (6) ◽  
pp. 875-878 ◽  
Author(s):  
H. Szillat ◽  
Hk. Müller-Buschbaum

Single crystals of Rb0.6K0.4CuMo3O10 have been prepared by crystallization from melts and investigated by X-ray diffractometer technique. They crystallize with orthorhombic symmetry, space group D2h16 -Pnma , a = 8.606(2), b = 7.595(3), c - 13.660(7) Å, Z = 4. The crystal structure of Rb0.6K0.4CuMo3O10 is characterized by the rare octahedral coordination of molybdenum and is related to (NH4)2Mo3O10 with respect to the one-dimensional 1∞[Mo3O10]- chains.


1995 ◽  
Vol 50 (5) ◽  
pp. 707-711 ◽  
Author(s):  
H. Szillat ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of (Cu,Co)3,75Mo3O12 have been prepared by recrystallization from melts and investigated by X-ray diffractometer techniques. The compound crystallizes with orthorhombic symmetry, space group D162h-Pnma, a = 5.092(1), b = 10.624(3), c = 17.804(4) Å, Z = 4 and is isotypic to NaCo2.31Mo3O12. The crystal structure is discussed and it is shown, that the trigonal prismatically coordinated copper positions are occupied in a different manner. One of the alternate sites is beside the centre of the prisms, and the other one is shifted towards one of the faces of the rectangular prism. This detail may be interpreted by assigning the valance states CuI and CuII. The MO6 octahedra are occupied statistically by copper and cobalt.


1995 ◽  
Vol 50 (11) ◽  
pp. 1653-1657 ◽  
Author(s):  
Anne Utzolino ◽  
Karsten Bluhm

Single crystals of Co1.5Ti0.5(BO3)O (I) and Co1.5Zr0.5(BO3)O (II) were obtained by a B2O3 flux technique. Both compounds crystallize with orthorhombic symmetry, space group D162h-Pnma (Nr. 62), I a = 928.1; b = 311.1; c = 940.1 pm; Z = 4 and II a = 949.5; b = 323.42; c = 934.7 pm; Z = 4. The compounds are isotypic to the mineral warwickite. All metal ions are octahedrally coordinated by oxygen ions. The structure contains isolated, trigonal planar BO3 units and oxygen that is not coordinated to boron.


1997 ◽  
Vol 52 (7) ◽  
pp. 785-789 ◽  
Author(s):  
R. Rettich ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of Ba(Ca0.6Mn0.4)V2O7 have been prepared by crystallization from melts. X-ray investigations revealed a new quaternary vanadium oxide of the type BaMV2O7. The M positions are occupied statistically by Ca2+ and Mn2+. The compound crystallizes with orthorhombic symmetry, space group D2h16-Pnma, a = 15.429(2), b - 5.7005(12), c = 7.364(2) Å, Z = 4. The crystal structure can be interpreted as a [Ba(Ca,Mn)O6] network with incorporated V-O- V groups. Considering the nearest O2- neighbours of the incorporated vanadium, the V-O-V groups are complemented to give V2O7 divanadate units. Ba(Ca0.6Mn0.4)V2O7 is isotypic to BaMV2O7 (M=Ca,Cd) but not to BaMnV2O7.


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