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'Phase transition' in keywords Facet   Publication Year 1999  [X]
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1999[X]
1Author    E. Mikuli, A. Migdał-Mikuli, S. WróbelRequires cookie*
 Title    Phase Transitions in Crystalline [Me(H 2 0) 6 ](BF 4 ) 2 . Part I (Me = Mn, Fe, Co, Ni and Zn)  
 Abstract    Solid polymorphism in five compounds of the type [Me(H 2 0) 6 ](BF 4) 2 , where Me = Mn, Fe, Co, Ni and Zn, have been studied in the temperature range 120 -330 K by DSC. For each substance at least three solid modifications have been found. In addition, for compounds with Me = Mn, Fe and Zn some new low temperature phase transitions have been observed. The transition temperatures for the [Me(H 2 0) 6 ](BF 4) 2 compounds are distinctly lower than those for the [Me(H 2 0) 6 ](C10 4) 2 compounds. The entropy-and enthalpy-changes at the phase transitions of the hexaaquametal(II) tetrafluoroborates are significantly lower than those for the corresponding chlorates(VII). Linear correlations between the highest transition temperature and the crystal density are found for both series of these isomorphous compounds. 
  Reference    Z. Naturforsch. 54a, 225—228 (1999); received December 12 1998 
  Published    1999 
  Keywords    Hexaaquametal(II) tetrafluoroborates, Phase Transitions, DSC Method 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0225.pdf 
 Identifier    ZNA-1999-54a-0225 
 Volume    54 
2Author    M. Sandmann, F. Hamann, A. WürflingerRequires cookie*
 Title    PVT and DTA Measurements on trans-4-w-Hexyl- (4'-CyanophenyI)-Cyclohexane (6PCH) up to 300 MPa  
 Abstract    The phase diagram of trans-4-n-hexyl-(4'-cyanophenyl)-cyclohexane, (6PCH) has been estab-lished by high-pressure differential thermal analysis. Specific volumes are presented for temper-atures between 300 and 370 K up to 300 MPa. The p,V m ,T data have been determined for the nematic, isotropic, and (partly, in the neighbourhood to the melting curve) solid phases. Volume and enthalpy changes along the phase transitions have also been calculated. As previously, the p,Vm,T data were used to calculate the volume entropy for the nematic-isotropic transition. The molar volumes along the clearing line T NI (p) enabled us to calculate the molecular field parameter 7 = ain T NI /3ln V NI , being 4.1. 
  Reference    Z. Naturforsch. 54a, 281—286 (1999); received March 13 1999 
  Published    1999 
  Keywords    6PCH, High Pressure, pVT, Phase Transitions, Thermodynamics 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0281.pdf 
 Identifier    ZNA-1999-54a-0281 
 Volume    54 
3Author    M. Massalska-Arodź, A. Würflinger, D. BüsingRequires cookie*
 Title    High-pressure DTA Studies of the Phase Behaviors of 4-n -butyl-thiocyanobiphenyl (4TCB) and 4-w-pentyl-4'-n-phenyl-cyanocyclohexane (5HCP)  
 Abstract    DTA measurements of 4-/i-butyl-thiocyanobiphenyl (4TCB) and/?-cyano-/?'-pentylphenyl-cyclohex-ane (5HCP) have been performed in the temperature range 220 K-390 K and pressures up to 400 MPa. For 4TCP a transition from a crystalline to a liquid crystal phase (probably smectic E) could be detect-ed at higher pressures > 90 MPa. The pressure dependence of the transition temperature has been estab-lished. At pressures lower than 88.7 MPa no transition of SmE into a crystal or into a glass has been found. For 5HCP only the melting curve was observed, in contrast to 5PCH, which displays a liquid crystalline nematic phase. 
  Reference    Z. Naturforsch. 54a, 675—678 (1999); received November 5 1999 
  Published    1999 
  Keywords    DTA, High Pressures, Phase Transitions, Liquid Crystals 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0675.pdf 
 Identifier    ZNA-1999-54a-0675 
 Volume    54 
4Author    E. Mikuli, A. Migdał-Mikuli, S. Wróbel, B. GradRequires cookie*
 Title    DSC Investigations of the Phase Transitions of [M(H 2 0) 6 ](N0 3 ) 2 , where M = Mn, Co, Ni, Cu and Zn  
 Abstract    The phase transitions of [M(H 2 0) 6 ](N0 3) 2 , where M = Mn 2+ , Co 2+ , Ni 2+ , Cu 2+ or Zn 2+ have been studied at 100 -400 K by DSC. Two phase transitions connected with a two-stage melting process have been found for these five compounds. For the compound with M = Co, besides the two melting points a solid-solid phase transition at 272 K has been found. 
  Reference    Z. Naturforsch. 54a, 595—598 (1999); received August 13 1999 
  Published    1999 
  Keywords    Hexaaquametal(II) nitrates, Phase Transitions, Melting Points, DSC Method 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0595.pdf 
 Identifier    ZNA-1999-54a-0595 
 Volume    54