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'Phase transitions' in keywords Facet   Publication Year 1987  [X]
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1987[X]
1Author    Akinobu Sasane, Hisanori Shinohara, Yoshihiro Mori, Yoshio Kume, Tetsuo Asaji, Daiyu NakamuraRequires cookie*
 Title    A Temperature Dependence Study of 35 C1 Nuclear Quadrupole Resonance Frequencies in Some Hexachloroplatinate(IV) Hexahydrates  
 Abstract    The temperature dependence of 35 C1 NQR frequencies was investigated in various hexachloro-platinate(IV) hexahydrates containing the following divalent ions as counter cations: Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Ba(II). All of the compounds except the Cu(II) and Ba(II) salts yield a single 35 C1 NQR line at all temperatures studied. For the Mn(II), Cu(II), and Ba(II) salts, the NQR frequencies are considerably shifted by deuteration. For the deuterated Mn(II) salt, two 35 C1 NQR lines were observed whose relative peak-height intensities vary in dependence on the history of the thermal treatment of the sample. The very broad higher frequency line could be observed for a sample which had been at 77 K or below. It could not be observed for a sample which was cooled slowly to room temperature after it had been heated up to ca. 420 K. A structural phase transition was located at 135. 6 and 129. 4 K for the Cu(II) salt and its deuterated analog, respectively. The frequency shift by deuteration is discussed in relation to the strength of O-H ... CI type hydrogen bonds. 
  Reference    Z. Naturforsch. 42a, 611—616 (1987); received February 171987 
  Published    1987 
  Keywords    Magnetic resonance (NQR), hydrogen bonding, phase transition 
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 TEI-XML for    default:Reihe_A/42/ZNA-1987-42a-0611.pdf 
 Identifier    ZNA-1987-42a-0611 
 Volume    42 
2Author    Wolfgang Hönle, Arndt Simon, Gabriele GerlachRequires cookie*
 Title    Darstellung, Kristallstruktur und Eigenschaften von ß-Ga 2 Br 4 Preparation, Crystal Structure and Properties of y3-Ga 2 Br 4  
 Abstract    The compounds Ga 2 Br 4 (a+ß) have been prepared by reacting GaBr 3 with Ga metal without a solvent or in a hydrocarbon medium. a-Ga 2 Br 4 is isotypic with Ga 2 Cl 4 , and /3-Ga 2 Br 4 with Ga 2 I 4 . Both forms have to be formulated as Ga + (GaBr 4)~ according to their crystal structures. The first order phase transition a—*ß has been investigated by means of DTA and temperature dependent X-ray powder photographs. The crystal structure of /3-Ga 2 Br 4 has been refined with single crystal data (R3c; a = 2163.4(8) pm; c = 869.2(4) pm; Z = 18; R = 0.037). Main building units are GaBr 4 " tetrahedra (d(Ga —Br) = 232.9 pm), connected in three dimensions by capped trigonal prisms (6+2+1) around Ga + . The crystal chemical relationships between y3-Ga 2 Br 4 and Ga 2 I 4 are discussed. 
  Reference    Z. Naturforsch. 42b, 546 (1987); eingegangen am 13. November 1986 
  Published    1987 
  Keywords    Phase Transition, DTA Investigation, Crystal Structure 
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 TEI-XML for    default:Reihe_B/42/ZNB-1987-42b-0546.pdf 
 Identifier    ZNB-1987-42b-0546 
 Volume    42