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'Dielectric constant' in keywords
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1996 (2)
1993 (1)
1992 (1)
1Author    S. Heinemann, H. Kresse, S. Saito, D. DemusRequires cookie*
 Title    Dielectric Studies of a Series of Liquid Crystalline Pyridine Derivates  
 Abstract    Measurements of the temperature and frequency dependence of dielectric constants have been performed for five homologues in the range 100 Hz -10 MHz. These substances exhibit a negative anisotropy of the dielectric constants and two relaxation regions (rotation of the molecules around the short resp. long axis) in the investigated frequency range. Even in the crystalline state dipolar reorientations are possible which have been interpreted as rotations of the alkoxy group. Changes of the static dielectric constants, relaxation frequencies and transition entropies are discussed as a measure of structural changes passing the several liquid crystalline phases. 
  Reference    Z. Naturforsch. 51a, 1019—1026 (1996); received May 3 1996 
  Published    1996 
  Keywords    Dielectric constants, Relaxation frequencies, Transition entropies, Tilted smectic phases 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-1019.pdf 
 Identifier    ZNA-1996-51a-1019 
 Volume    51 
2Author    S. Heinemann, H. Kresse, S. Urban, R. DabrowskiRequires cookie*
 Title    Dielectric Investigations in Smectic B-Phases  
 Abstract    Several liquid crystalline substances exhibiting S B -phases have been investigated by dielectric and calorimetric measurements. Special attention is taken to the low frequency relaxation process at the phase transition nematic-S B . From the large change of relaxation frequencies, crystallinity of the S B -phases has been concluded. Nevertheless, motion is still present and not frozen. 
  Reference    Z. Naturforsch. 51a, 1203—1208 (1996); received July 26 1996 
  Published    1996 
  Keywords    Smectic B-phase, Dielectric constant, Relaxation frequency, Transition entropy 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-1203.pdf 
 Identifier    ZNA-1996-51a-1203 
 Volume    51 
3Author    H. G. Kreul, R. Waldinger, A. WürflingerRequires cookie*
 Title    Differential Thermal Analysis and Dielectric Studies on Neopentanol under Pressure  
 Abstract    Differential thermal analysis (DTA) and dielectric measurements have been performed on 2,2-di-methyl-l-propanol (neopentanol) up to 200 MPa. Neopentanol exhibits at least one orientationally disordered (ODIC) phase (solid I) that transforms at lower temperatures to a non-plastic phase (solid II). There is evidence of a further ODIC phase denoted as solid I'. The pressure dependence of the phase transitions and the dielectric behaviour up to frequencies of 13 MHz are described. Activation enthalpies and volumes are derived from the dielectric relaxation time and compared with results for other alcohols. 
  Reference    Z. Naturforsch. 47a, 1127—1134 (1992); received July 27 1992 
  Published    1992 
  Keywords    High pressure, DTA, Phase transitions, Dielectric constant, and relaxation 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1127.pdf 
 Identifier    ZNA-1992-47a-1127 
 Volume    47 
4Author    J. Reuter, T. Brückert, A. WürflingerRequires cookie*
 Title    Differential Thermal Analysis under Pressure on Cyanocyclohexane, 1,2,3,4-Tetrahydro-5,6-dimethyl-1,4-methanonaphthalene, and 2-Methyl-2-propanol  
 Abstract    Differential thermal analysis has been performed on cyanocyclohexane (CCH), 1,2,3,4-tetrahydro-5,6-dimethyl-1,4-methanonaphthalene (TDMN), and 2-methyl-2-propanol (t-butanol) up to 300 MPa. The latter compound was also investigated dielectrically. CCH displays an ODIC phase that transforms only reluctantly to the low-temperature stable phase II. Annealing under pressure can appreciably accelerate this transformation. For all three compounds the phase diagrams were established. For CCH and TDMN also the pressure dependence of the glass transition has been determined. 
  Reference    Z. Naturforsch. 48a, 705—708 (1993); received March 10 1993 
  Published    1993 
  Keywords    High pressure, DTA, Phase transitions, Glass transition, Dielectric constant 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0705.pdf 
 Identifier    ZNA-1993-48a-0705 
 Volume    48