Ba4Mn2Ag2O(As04)4 , ein Barium-Mangan-Oxid-Arsenat mit nichtlinearen O-Ag-O-Hanteln / Ba4Mn2Ag2O(AsO4)4, a Barium Manganese Oxide-Arsenate Showing Nonlinear O-Ag-O Dumbbells

1998 ◽  
Vol 53 (5-6) ◽  
pp. 512-516 ◽  
Author(s):  
M. Staack ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of Ba4Mn2Ag2O(AsO4)4 have been prepared by solid state reactions using metallic silver as reactant. X-ray techniques led to monoclinic symmetry, space group D2h-P2,/m, a = 8.739(2), b = 5.912(1), c = 9.440(2) Å, β = 115.21(1)°, Z = 1. The crystal structure is characterized by O-Ag-O dumbbells, bond angle = 165,3°, containing one oxygen atom not associated with the arsenate groups. Considering these facts Ba4Mn2Ag2O(AsO4)4 may be seen as an oxide-arsenate or an oxoargentate(I)-arsenate. Assuming the oxidation state +II for manganese, as confirmed by magnetic measurements, the compound has an oxygen deficite which was accounted for by a split position model.

1997 ◽  
Vol 52 (5) ◽  
pp. 549-552 ◽  
Author(s):  
S. Meyer ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of the new compound BaCa(VO)(PO4)2 have been prepared by solid state reactions below the melting point of the reactants in evacuated quartz tubes. X-ray investigations led to monoclinic symmetry, space group C2h5 - P21/c, a = 7.300(1), b = 7.053(1), c = 14.460(1) Å, β = 101,43(1)°, Z = 4. The crystal structure is characterized by layers of corner-and edge-connected PO4 tetrahedra and VO1+5 octahedra. There is an unusually short O(1)-O(4) distance in a VO6 octahedron of 2.44 Å associated with the sharing of edges with PO4 tetrahedra. The short V-O distance of 1.61 Å indicates a vanadyl group.


1994 ◽  
Vol 49 (7) ◽  
pp. 927-930 ◽  
Author(s):  
S. Münchau ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of Cd0.73Cu0.27V2O6 were prepared by solid state reactions. X-ray investigations lead to monoclinic symmetry, space group C32h-C2/m , a = 9.339, b = 3.5604, c = 6.893 Å, β = 111.85°, Z = 2. It belongs to the Brannerite structure, showing a statistical distribution of Cd2+ and Cu2+ on one point position. The crystal structure of Brannerites is discussed with respect to the distorted O2- octahedra around V5+ and the influence of the Jahn-Teller active Cu2+ ion to the shortened M2+O6 octahedra.


1996 ◽  
Vol 51 (10) ◽  
pp. 1407-1410 ◽  
Author(s):  
B. Wedel ◽  
Hk. Müller-Buschbaum

Single crystals of Ba2Nb2TeO10) have been prepared by solid state reactions in air. X-ray investigations led to orthorhombic symmetry, space group D152h-Pbca, a = 7.242(4), b = 12.433(3), c = 9.932(3) Å. Z = 4. Nb5+ and Te6+ show octahedral coordination by O2- . The crystal structure is characterized by planes of edge- and corner-sharing NbO6- and TeO6octahedra. It is shown that in spite of nearly identical lattice constants of Ba2Nb2TeO10 with compounds of the composition M0,5BaNbTe2O9 the so far unknown crystals of these substances may not be derived from the Ba2Nb2TeO10 type.


1996 ◽  
Vol 51 (7) ◽  
pp. 929-933 ◽  
Author(s):  
C. Wadewitz ◽  
Hk. Müller-Buschbaum

Dark green single crystals of Sr2(VO)P2O8 have been prepared by solid state reactions in closed quartz tubes. X-ray investigations led to monoclinic symmetry, space group C2h6-I2/a, a = 6.744(4), b = 15.866(4), c = 7.032(2) Å, β = 115.41(2), Z = 4. Sr2(VO)P2O8 is isotypic to Sr2(VO)V2O8 and shows V4+ in split positions. The split positions are in non-centric octahedral coordination forming a short vanadium to oxygen distance typical for the vanadyl group. The crystal chemistry of the monovanadyl orthophate Sr2(VO)P2O8 is discussed considering related divanadyl phosphates.


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.


1998 ◽  
Vol 53 (2) ◽  
pp. 149-152 ◽  
Author(s):  
L. Wulff ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of LaTi(Ti0.25Te0.75)O6 have been prepared by solid state reactions. X-ray investigations led to trigonal symmetry, space group C31-P3 , a = 5.141(10), c = 5.218(10) Å, Z = 1. The compound is characterized by a predominantly ordered distribution of Ti4+ and Te6+. Typical features of the crystal structure are staggered layers containing edge connected TiO6 and (Ti,Te)O6 octahedra. The layers are connected by La3+ ions receiving an octahedral coordination by the surrounding oxygen ions. The relationships to the PbSb2O6 type and the recently described compound Sr(MnTe)O6 are discussed.


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.


1997 ◽  
Vol 52 (1) ◽  
pp. 83-87 ◽  
Author(s):  
C. Wadewitz ◽  
Hk. Müller-Buschbaum

A new alkaline earth vanadyl arsenate Ba(VO)4(AsO4)2(As2O7) has been synthesized by solid state reactions in closed quartz tubes. X-ray investigations led to orthorhombic symmetry, space group D162h-Pnma, α = 17.540(2), b = 7.6223(8), c = 11.0633(12) Å, Z = 4. The crystal structure is characterized by AsO4 single and As2O7 double tetrahedra and face shared asymmetric stretched V2O8+1, double octahedra, forming a network of polyhedra. The incorporated Ba2+ ions show 12-fold coordination by oxygen. Ba(VO)4(AsO4)2(As2O7) is the first vanadyl compound containing V2O8 divanadyl groups originating from face sharing stretched VO5+1 octahedra


1998 ◽  
Vol 53 (3) ◽  
pp. 279-282 ◽  
Author(s):  
R. Rettich ◽  
Hk. Müller-Buschbaum

Abstract Single crystals of Ag2 SrMnV2O8 have been prepared by reactions of metallic silver and a mixture of SrCO3, MnCO3 · H2O and V2O5. X-Ray investigations showed monoclinic symmetry, space group C62h -C2/c, a = 9.7022(9), b = 5.5882(5), c = 13.894(1), β = 90.41(1)°, Z = 4. The crystal structure is isotypic to Na2BaCuV2O8 and includes VO4 tetrahedra, MnO6 octahedra as well as irregular AgO8 and SrO10 polyhedra. Ag2SrMnV2O8 is characterized by a [MnV2O8] network incorporating Ag+ and Sr2+ or a [Ag2V28] frame incorporating Mn2+ and Sr2+ ions. Ag+ is able to replace an alkali ion in the cationic part of the crystal structure.


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