Über ein cadmiumreiches Orthovanadat Ba2,5Cd11(VO4)9 mit Cadmium in oktaedrischer und tetragonal pyramidaler Koordination / On a Cadmium Rich Orthovanadate Ba2,5Cd11(VO4)9 Showing Cadmium in Octahedral and Square Pyramidal Coordination

1997 ◽  
Vol 52 (8) ◽  
pp. 989-993 ◽  
Author(s):  
B Mertens ◽  
Hk Müller-Buschbaum

Single crystals of Ba2,5Cd11(VO4)9 have been prepared by solid state reactions. The new compound crystallizes with orthorhombic symmetry, space group D142h-Pbcn, a = 20.842(6), b = 13.471(3), c = 11.838(9) Å, Z = 4. The crystal structure is characterized and dominated by CdO6 octahedra and unusual square pyramids of O2- around Cd2+ forming a three-dimensional [Cd11O36] network. The interstices are occupied by V5+ and Ba2+ ions. This results in VO4 tetrahedra and irregular BaO10 polyhedra isolated from each other. Occupation of the barium positions is deficient in agreement with the valence state V5+ and calculations of the coulomb terms of lattice energy.


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.



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



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.



1997 ◽  
Vol 52 (5) ◽  
pp. 643-646 ◽  
Author(s):  
M. Staack ◽  
Hk. Müller-Buschbaum

Abstract The compound Co6O2 [TeO4(CoAsO5)2] has been prepared by solid state reactions. Single crystal X -ray techniques led to orthorhombic symmetry, space group D 182h-Cmca, a = 6.020(1), b = 23.763(5), c = 8.841(2) Å , Z = 4. The new structure type contains the hitherto unknown cobaltoarsenate group CoAsO7, oxidic oxygen connected exclusively to cobalt, and TeO6 octahedra.



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 (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.



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.



1997 ◽  
Vol 52 (8) ◽  
pp. 981-984 ◽  
Author(s):  
S Meyer ◽  
Hk Müller-Buschbaum

Abstract Single crystals of the new compound CaNi(VO)(PO4)2 have been prepared by solid state reactions below the melting point of the oxide mixture in evacuated quartz tubes. X-ray investigations led to orthorhombic symmetry, space group D2h16-Pnma, a =14.113(1), b =6.408(1), c = 7.364(1) Å, Z = 4. The crystal structure shows 1∞[NiO4] and 1∞[VO6P2O3] polyhedra chains closely related to analogous chains in the isotypic compound CdV2O(PO4)2. The short V -O distance of 1.66 Å indicates a vanadyl group as the main difference to CdV2O(PO4)2. The short O-O distance of 2,395 Å of the edge-sharing PO4 tetrahedra and VO6 octahedra is discussed.



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.



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.



Sign in / Sign up

Export Citation Format

Share Document