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'Perovskites' in keywords Facet   Publication Year 2000  [X]
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2000[X]
1Author    G. C. Papavassiliou3, G.A M Ousdis3, C. P. Raptopouloub, A. TerzisbRequires cookie*
 Title    Some New Luminescent Compounds Based on 4-MethyIbenzylamine and Lead Halides  
 Abstract    Compounds of the general formula (CH3NH3)"_i(C H 3C6H4C H 2N H 3)2Pb"X3"+i, where X = I, Br, Cl and n= 1,2, 3,..., were prepared and characterized analytically and spectroscopically. Moreover, (CH3C6H4CH2NH3)2PbX4 and (C H ^ N H jX C ^ C e ^ C H z N H jh P b il? were charac­ terized by X-ray crystal structure analysis. Their optical absorption and photoluminescence spectra exhibit excitonic bands, even at room temperature. 
  Reference    Z. Naturforsch. 55b, 536—540 (2000); received March 6 2000 
  Published    2000 
  Keywords    Hybrides, Perovskites, Excitonic Spectra 
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 TEI-XML for    default:Reihe_B/55/ZNB-2000-55b-0536.pdf 
 Identifier    ZNB-2000-55b-0536 
 Volume    55 
2Author    R. E. Alonso, A. López-GarcíaRequires cookie*
 Title    Charge Distribution Model in Cubic Perovskite-type Compounds  
 Abstract    A non-zero electric field gradient tensor, detected by probes that occupy sites with cubic point group symmetry, was observed in many AB0 3 perovskite-type compounds. This breakdown of local cubic symmetry is commonly associated with the presence of oxygen vacancies around the probe. This effect in BaT^Hfi-^O-, with x = 0.7, 0.5, 0.3, 0.1, 0.05 and 0.01 is studied in this work. The cell parameters were obtained at laboratory temperature using XRD spectroscopy. The hyperfine parameters were measured at a 1X1 Ta probe in the B site using Perturbed Angular Correla-tions (PAC) spectroscopy as a function of both temperature and composition. As a common trend, a static asymmetric and distributed quadrupolar interaction, strongly dependent on composition has been observed. The results, together with those corresponding to 1 > x > 0.75, are analyzed using the point-charge model in terms of polarized oxygen vacancies, different covalence of the Ti-0 and Hf-0 bonds with computational simulation for the lattice positions of cations and oxygen vacancies. 
  Reference    Z. Naturforsch. 55a, 261—266 (2000); received August 25 1999 
  Published    2000 
  Keywords    Perovskites, Ferroelectrics Materials, Defects, Polarized Oxygen Vacancies, Electric Field Gardient 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0261.pdf 
 Identifier    ZNA-2000-55a-0261 
 Volume    55