Kristallstrukturuntersuchung an einem Strontium-Vanadyl-Vanadat: Sr2(VO)V2O8 / Crystal Structure Investigation of the Strontium Vanadyl-Vanadate: Sr2(VO)V2O8

1995 ◽  
Vol 50 (1) ◽  
pp. 43-46 ◽  
Author(s):  
J. Feldmann ◽  
Hk. Müller-Buschbaum

Single crystals of Sr2(VO)V2O8 have been prepared by quenching melts from higher temperatures. This compound represents a new structure type and crystallizes with monoclinic symmetry, space group C62h–I2/a, a = 6.929, b = 16.246, c = 7.260 Å, β = 115.82°, Z = 4. The point positions occupied by V5+ show tetrahedral coordination. The refinement of the V4+ position led to split positions with acentric orientations of V4+ in the octahedral O2- surrounding. It results in a square pyramidal coordination with one short V–O distance typically for vanadyl groups.

1996 ◽  
Vol 51 (4) ◽  
pp. 489-492 ◽  
Author(s):  
J. Feldmann ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of Ba2(VO)V2O8 have been prepared by solid state reactions of Ba2V2O7, V2O3 and V2O5 in sealed silica tubes. This compound crystallizes with monoclinic symmetry, space group C22 -P21, a = 8.1174(9), b = 5.9699(9), c = 9.2903(9) Å , β = 113.94(1)°, Z = 2. V 5+ shows tetrahedral coordination. V 4+ inside 1∞ [V (3)O4] chains is characterized by a square pyramidal coordination with a short apical V-O distance of 1.6 Å typically for vanadyl groups. Ba2(VO)V2O8 represents a new structure type and is not isotypic to Sr2(VO)V2O8.


1995 ◽  
Vol 50 (5) ◽  
pp. 717-720 ◽  
Author(s):  
H. Szillat ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of the hitherto unknown compound CuSbMo2O8 were prepared by recrystallization from melts in closed copper tubes and investigated by X-ray diffractometer technique. CuSbMo2O8 crystallizes in a new structure type with monoclinic symmetry, space group C62h - I12/a1, a = 5.554(2), b = 4.916(1), c = 21.519(4) Å, β = 93.42(3)°, Z = 4. The crystal structure shows SbIII in a one-sided coordination by four oxygen. Molybdenum shows the rare octahedral coordination by oxygen. MoO6 and CuO6 octahedra form triple layers stacked and connected by Sb ions along [001].


1994 ◽  
Vol 49 (3) ◽  
pp. 350-354 ◽  
Author(s):  
Holger Szillat ◽  
Hanskarl Müller-Buschbaum

Abstract Single crystals of KCuHo2Mo4O16 have been prepared by recrystallisation from melts and investigated by X-ray diffractometer techniques. The compound crystallizes with monoclinic symmetry, space group C 2/c, a = 521.6(1), b = 1251.3(2), c = 1953.1(2) pm, β = 92.903(18)°, Z = 4. KCuHo2Mo4O16 represents a new structure type characterized by HoO8 and alternate CuO6/KO10 polyhedra chains. The connection of these polyhedra chains to each other and by MoO4 tetrahedra is described and the crystal structure discussed with respect to related compounds of the CuLnMo2O8 and KLnMo2O8 types.


1995 ◽  
Vol 50 (2) ◽  
pp. 252-256 ◽  
Author(s):  
H. Szillat ◽  
Hk. Müller-Buschbaum

Single crystals of AgKCu3Mo4O16 have been prepared by crystallization from melts and investigated by X-ray diffractometer techniques. This compound crystallizes with monoclinic symmetry, space group C2h5 - P21/c, a = 5.056(1), b = 14.546(4), c = 19.858(9) Å, β = 86.64(5)°, Z = 4. The crystal structure of AgKCu3Mo4O16 is closely related to K2Cu3Mo4O16 showing ribbons of edge-sharing CuO6 and AgO7 polyhedra. The ribbons are linked by tetrahedrally coordinated molybdenum and K2O10 groups. Another kind of MoO4 tetrahedra occupies the cavities inside the ribbons. The crystal structure and the coordination of silver, copper, potassium and molybdenum by oxygen are discussed with respect to K2Cu3Mo4O16.


1994 ◽  
Vol 49 (11) ◽  
pp. 1463-1466 ◽  
Author(s):  
D. Frerichs ◽  
Hk. Müller-Buschbaum

Single crystals of KCo3Cu(As2.58V0.42)O12 were prepared by solid state reactions below the melting point of the reaction mixture (K2CO3, CuO, COC2O4, V2O5 and 3 As2O5 · 5H2O). It crystallizes with monoclinic symmetry, space group C62h-C2/c, a = 12.207, b = 12.730, c = 6.811 Å, β = 113.69°, Z = 4. The structure type is characterized by isolated twisted-square CuO4-polygons, CoO6-octahedra and a special 4+4-coordination of the potassium ion. As5+ and V5+ are in tetrahedral coordination with a partly statistical distribution of these ions.


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.


1998 ◽  
Vol 53 (3) ◽  
pp. 287-290 ◽  
Author(s):  
B. Wedel ◽  
L. Wulff ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of Pb2TeO5 have been prepared by flux techniques. X-ray investigations showed a new crystal structure with monoclinic symmetry, space group C4S -Cc, a = 13.099(3), b = 5.714(1), c = 7.520(2) Å, β = 123,80(3)°, Z = 4. Pb2TeO5 is characterized by 1∞[TeO5] chains of octahedra isolated from each other and incorporated into an edge, corner and face connected frame of PbO7 polyhedra. Possible positions of the lone pair of electrons of Pb2+ are estimated by calculations of Coulomb terms of lattice energy.


1996 ◽  
Vol 51 (1) ◽  
pp. 85-89 ◽  
Author(s):  
St. Gallinat ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of (I) BaCu0,41Pr2Mo4O16 and (II) BaYb2Mo4O16 have been prepared by flux technique. Both compounds crystallize with monoclinic symmetry, space group C62h-C2/c with (I): a = 5.352(11), b = 12.888(2), c = 19.399(4) Å; β = 90.89(3)°; (II): a = 5.181(7), b = 12.467(3), c -19.350(3) Å , β -91.93(2)°, Z = 4. The crystal structure is characterized by 1∞[BaMO12]-chains along [010]. In the first case the M positions are occupied by copper by about 41%, in the second case these positions remain completely unoccupied. With respect to the crystal chemistry of the reference compound Ba(Cu0.22Mg0,78)Nd2Mo4O16 all substances of the composition BaLn2Mo4O16 should be written as Ba▪Ln2Mo4O16 indicating the holes in the 1∞[BaMO12]-chains by ▪.


1996 ◽  
Vol 51 (2) ◽  
pp. 229-232 ◽  
Author(s):  
S. Münchau ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of Cd1.35Cu1.65(PO4)2 have been prepared by solid state reactions below the melting point of the starting compounds. The light green crystals crystallize with monoclinic symmetry, space group C52h-P21/c , a = 9.062(2), b = 11.669(2), c = 5.950(2) Å , β = 97.88(2)°, Z = 4. Cd1.35Cu1.65(PO4)2 shows relationship to the mineral graftonite. The crystal structure is characterized by nets of corner connected Cd2O12 polyhedra. One point position is statistically occupied by Cd2+ and Cu2+ ions.


1997 ◽  
Vol 52 (4) ◽  
pp. 457-461 ◽  
Author(s):  
R. Rettich ◽  
Hk. Müller-Buschbaum

Single crystals of Ba5(Mg0,4Mn0,6)(V207)2MnCl6 have been prepared by solid state reactions of MgCO3, Mn2O3, V2O5 and BaCl2·2H2O below the melting point of BaCl2. The new vanadium oxide chloride crystallizeswith monoclinic symmetry, space group C42h-P2/c, a = 13.345(4), b = 5.711(2), c = 15.859(4) Å, β = 113.69(2)°, Z = 2. Special features of the crystal structure are isolated MnCl6 octahedra and layers created by divanadat groups and (Mg,Mn)O6 octahedra. The 2∞ [(Mg,Mn)V2O7] nets of Ba3(Mg0,4Mn0,6)(V2O7)2MnCl6 are discussed with respect to other oxohalogeno vanadates Containing divanadate groups.


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