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'borates' in keywords Facet   Publication Year 1998  [X]
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1998[X]
1Author    PhilipJ. Bray, GaryL. PetersenRequires cookie*
 Title    NMR and NQR Studies of Borate Glasses  
 Abstract    Nuclear magnetic resonance (NMR) has been used for some 40 years to study atomic arrange-ments, chemical bonding, and structural groupings in borate glasses and crystalline compounds, and nuclear quadrupole resonance (NQR) has more recently increased the resolution and accuracy of the measurements. Examples are presented of the use of first-order and second-order quadrupo-lar effects in "B NMR spectra to obtain structural information, and n B and 10 B NQR spectra to obtain the quadrupolar parameters Q cc (the coupling constant) and 77 (the asymmetry parameter) with accuracies of 5 or 6 significant figures, and 3 figures, respectively. Q cc and 77 are extremely sensitive to changes in atomic rearrangements and chemical bonds, so they are excellent monitors and provide identification of bonding configurations and structural groupings in borates: Examples are also presented in which combinations of NMR and NQR data are used to extract the desired information. NQR detection of resonances at frequencies as low as 276 kHz is discussed. 
  Reference    Z. Naturforsch. 53a, 273—284 (1998); received December 30 1997 
  Published    1998 
  Keywords    NMR, NQR, Borates, Quadrupolar Interactions 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0273.pdf 
 Identifier    ZNA-1998-53a-0273 
 Volume    53 
2Author    Andre Wiesch3, Hauke Timmb, Karsten Bluhm3Requires cookie*
 Title    Uber CuDy2[B80 16] und CuHo2[B80 16]: Zwei neue "Metaborate" mit einem ^ [B80 16]g_-Anion On CuDy2[B80 16] and CuHo2[B80 16]: Two New "Metaborates" with a ^ [B80 16]8-Anion  
 Abstract    Nearly colourless single crystals of the compounds CuDy2 [B80 i 6] (I) and CuHo2[B80)6] (II) have been obtained by a B20 3 flux technique. They crystallize in the structure of CuTb2 [B80)6] (I) or in an orthorhombic variant (II). X-ray investigations on single crystals led to the space group C2h -P2!/c (Nr. 14) with lattice parameters a = 1025,5(10); b = 836,99(10); c = 621,2(8) pm, ß = 90.47(10)°; Z = 2 (I) and D^h -Pbam (Nr. 55) with a = 840,7(2), b = 616,6(2), c = 1022,0(2) pm, Z = 2 (II). The structures contain 1 [B80 16]8_ chains isolated from each other, which include tri-and tetracoordinated boron, T'fie chains consist of alternating twelve and eight-membered rings of boron and oxygen atoms connected by B 0 4 units. Dy,+ and H o 3+ are octacoordinated and Cu2+ is hexacoordinated in elongated octahedra by oxygen. The relation between these two structures is discussed. 
  Reference    (Z. Naturforsch. 53b, 1—4 [1998]; eingegangen am 23. Oktober 1997) 
  Published    1998 
  Keywords    Copper, Lanthanoids, Borate, Synthesis, Crystal Structure 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-0001.pdf 
 Identifier    ZNB-1998-53b-0001 
 Volume    53 
3Author    Lanthanoid Borates, A. Wiesch, K. BluhmRequires cookie*
 Title    CuHo2[B20 5]2* Ein unerwarteter Strukturtyp in der Reihe der Kupferlanthanoidborate CuHo2[B20 5]2: An Unexpected Structure Type in the Series of Copper  
 Abstract    Single crystals of the new compound CuHo2 [B20 5 ]2 were obtained by using a B20 3 flux technique with CuO and Ho20 3 at 1050 °C. X-ray investigations on single crystals led to the space group P 2,/c (Nr. 14) with lattice parameters a = 454.3(2); b = 726.0(4); c = 936.0(5) pm; ß = 90.77(1)°; Z = 2. The compound is isotypic to CuTb2[B20 5 ] 2 as well as to the gadolinite structure (FeY2 [BeSi05]2). The structure exhibits layer-like 2 [B20 5]4~, a two-dimensional anion consisting of edge sharing B 0 4 -tetrahedra, which form four-and eight-membered rings. The layers are connected by elongated C u06-octahedra and slightly distorted tetragonal LnOs-antiprisms. 
  Reference    (Z. Naturforsch. 53b, 5—8 [1998]; eingegangen am 23. Oktober 1997) 
  Published    1998 
  Keywords    Copper, Holmium, Borate, Synthesis, Crystal Structure 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-0005.pdf 
 Identifier    ZNB-1998-53b-0005 
 Volume    53 
4Author    Helical Borate, AnionA. Wiesch, K. BluhmRequires cookie*
 Title    Ag2Cs[B1 5 0 2 4]* Ein wasserfreies quaternäres SiIber(I)-Borat mit einem neuartigen Boratanion mit helixartigem Aufbau Ag2C s[B 150 24]: An Anhydrous Quaternary Silver(I)-Borate with a New  
 Abstract    Single crystals o f Ag2C s[B ,50 24] were prepared by using a B 20 3 flux technique with Ag2C 0 3 and Cs2C 0 3 in a closed silver tube at 650 °C. X-Ray investigations led to a new crystal structure in the space group P 2 ,2 ,2 (Nr. 18) with lattice parameters a = 1778.7 (4); b = 2219.2 (4); c = 512.2 (1) pm, Z = 4. The silver atoms are part of distorted A g 0 4 tetrahedra and planar A g 0 3 units while the caesium atoms are eightfold coordinated by oxygen. The compound contains an as yet unknown borate anion [B,50 24] with twelve B 0 3-and three B 0 4 units per formula. The B 0 3 units are connected to eight cords twisted to helices which are combined via B 0 4 tetrahedra to a three dimensional framework with large tunnels occupied by the cations. 
  Reference    Z. Naturforsch. 53b, 157—160 (1998); eingegangen am 23. Oktober 1997 
  Published    1998 
  Keywords    Silver, Caesium, Borate, Synthesis, Crystal Structure 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-0157.pdf 
 Identifier    ZNB-1998-53b-0157 
 Volume    53