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'35C1 N Q R' in keywords
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1994 (2)
1Author    K. Yamada, K. Isobe, T. Okuda, Y. FurukawaRequires cookie*
 Title    Successive Phase Transitions and High Ionic Conductivity of Trichlorogermanate (II) Salts as Studied by 35C1 NQR and Powder X-Ray Diffraction  
 Abstract    A series o f trichlorogermanate(II) salts (AG eCl3, A = Rb, Cs, C H 3N H 3, and (C H 3)4N) have been synthesized and characterized by 35C1 N Q R , 35C1 N M R , AC conductivity, DTA, and X-ray diffrac­ tion techniques. In the temperature range studied two, two, five, and four phases were confirmed for the Rb, Cs, C H 3N H 3, and (C H 3)4N salts, respectively. From the 35C1 N Q R and structural data, isolated pyramidal G eC l3 anions were recognized in the low temperature phases. With increasing temperature the relaxation times of the 35C1 N Q R decreased exponentially and the signals disap­ peared far below the melting point. This suggests that the reorientation of the anion about the pseudo three-fold axis is excited. With further increase in temperature, the ionic conductivity of C H 3N H 3G eC l3 and (C H 3)4N G eC l3 increased drastically at the phase transitions to their cubic perovskite phases (C H 3N H 3G eC l3: a = 10-1 S m -1 at 400 K, (C H 3)4N G eC l3: a = 5 x 10-2 S m _1 at 420 K). The mobile ion was confirmed to be the chloride ion by means of 35C1 N M R and X-ray diffraction. 
  Reference    Z. Naturforsch. 49a, 258 (1994); received July 23 1993 
  Published    1994 
  Keywords    35C1 N Q R, 35C1 N M R, Ionic conductivity, Rietveld analysis, Phase transition 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0258.pdf 
 Identifier    ZNA-1994-49a-0258 
 Volume    49 
2Author    Hirokazu Nakayama, Taro Eguchi, Nobuo NakamuraRequires cookie*
 Title    Phase Transitions in 4,4'-Dichlorobenzophenone as Studied by 3SC1FT-NQR  
 Abstract    The temperature dependence of 35C1 N Q R frequencies in 4,4'-dichlorobenzophenone was m ea­ sured between 9.3 and 372 K by the pulse Fourier-transform method. Successive phase transitions were observed at 189 and 194 K. Concerning these phase transitions, the curious thermal hysteresis phenom enon found in a previous N Q R experiment was not reproduced in the present study. It also follow s that N Q R indicates another phase transition around 220 K, although no thermal anom aly was detected there by DTA. Tentative explanations for these three phase transitions are presented in relation to the incommensurability between 189 and 220 K. In addition, a novel phase transition was found to occur at 331 K according to both DTA and 35C1 N Q R. A single N Q R line observed at room temperature splits into two com ponents above 331 K, suggesting that the symmetry above 331 K is lower than that at room temperature. This is the behavior o f re-entrant phase transition, and it reveals the quasi-continuous nature. 
  Reference    Z. Naturforsch. 49a, 267 (1994); received August 21 1993 
  Published    1994 
  Keywords    35C1 N Q R, 4, 4'-dichlorobenzophenone, Phase transition, Incomm ensurate phase 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0267.pdf 
 Identifier    ZNA-1994-49a-0267 
 Volume    49