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1995 (2)
1Author    M. Born, C. Feike, H. W. Jäger, SpiessRequires cookie*
 Title     
 Abstract    Dedicated to Prof. W . Müller-Warmuth on the occassion of his 65th birthday Recently, 31P two-dimensional (2D) NMR has been proposed as a powerful tool for direct investigations of the connectivities between the Q" units in glasses, i.e. the medium-range order. In this paper, the principles of these experiments and applications to both polycrystalline Mg2P20 7 and a Na20 -P 2C>5 glass are demonstrated, including a theoretical description and modelling of the polarization transfer between the two inequivalent phosphorus sites in the magnesium pyrophos­ phate. 2 D 31P E x c h a n g e N M R : A new A p p r o a c h f o r a D ir e c t P r o b in g o f th e C o n n e c tiv itie s o f Q 1 U n its in G la s s e s 
  Reference    Z. Naturforsch. 50a, 169—176 (1995); received September 26 1994 
  Published    1995 
  Keywords    Exchange NMR, Connectivities, Phosphate glasses, Dipolar coupling, MAS 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0169.pdf 
 Identifier    ZNA-1995-50a-0169 
 Volume    50 
2Author    P. Hartmann, G. SchelerRequires cookie*
 Title      
 Abstract    Herrn Prof. W . Müller-Warmuth zum 65. Geburtstag gewidmet Is solid state 91 Zr NMR feasible? 91Zr solid state NMR spectra have been observed for samples possessing different zirconium local-site environments (e.g. phosphates, fluorides). Depending on the quadrupole coupling, different NMR experiments have been utilized. In case of weak quadrupole coupling, magic angle spinning (MAS) is suitable. Otherwise, spin echo techniques are necessary to overcome "acoustic ringing" and receiver dead-time limitations. Using the step echo method, the detection of the very broad 91Zr signals is not limited by non-uniform spectral excitation. The obtained 91Zr chemical shifts range from —246 ppm to 208 ppm, the quadrupole coupling frequencies from 50 kHz to 2.7 MHz.. I s t 91Z r -F e s tk ö r p e r -K e r n r e s o n a n z s p e k tr o s k o p ie p r a k tik a b e l? 
  Reference    Z. Naturforsch. 50a, 90—94 (1995); received September 26 1994 
  Published    1995 
  Keywords    Solid state NMR, Zirconium-91, MAS, Spin echo, Acoustic ringing 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0090.pdf 
 Identifier    ZNA-1995-50a-0090 
 Volume    50