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1Author    S. Sh, A. Soulayman, HarfoushRequires cookie*
 Abstract    a lc u la tio n o f th e M e ltin g C u rv e s o f s o m e A lk a li-h a lid e s w ith C s C l S tr u c tu r e a n d th e ir T h e r m o d y n a m ic P r o p e r tie s a lo n g th e s e C u rv e s The paper presents a study of three semi-empirical laws of melting. The study utilises the Im­ proved Unsymmetrized Self-Consistent Field Method (IUSCFM) for strongly anharmonic crystals with complex lattice and the energy criterion in calculating the melting curves of some alkali-halides. The energy criterion was proven correct along the melting curves particularly in the case of CsCl type of structure. The calculations of the melting curves for crystals of nine alkali-halides (KCl, KBr, KI, RbCl, RbBr, Rbl, CsCl, CsBr, Csl) are presented. The thermodynamic properties of these salts along the curves are also determined. A comparison of the calculated results and the experimental data is included. 
  Reference    Z. Naturforsch. 44a, 513—518 (1989); received October 27 1988 
  Published    1989 
  Keywords    Melting curves, Alkali-halides, Thermodynamic properties, Energy criterion, CsCl structure 
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 TEI-XML for    default:Reihe_A/44/ZNA-1989-44a-0513.pdf 
 Identifier    ZNA-1989-44a-0513 
 Volume    44 
2Author    S. Sh, SoulaymanRequires cookie*
 Title    Theoretical Melting Curves of Alkali Halides  
 Abstract    An analysis of the melting curves of alkali halides is given. The study is based on the Improved Unsymmetrized Self-Consistent Field Method (IUSCFM) for strongly anharmonic crystals with complex lattice and the energy, entropy and Ross's criterions in calculating the melting curves of alkali halides. The anharmonicities up to sixth order have been taken into consideration. The energy criterion was proven to be the most correct one along the melting curves of the high pressure modification (CsCl structure) while the entropy and Ross's criterions lead to a little better agreement with experiment than the energy criterion when dealing with rocksalt structure. Calculations of the melting curves of KCl and CsCl are compared with the experimental results. 
  Reference    Z. Naturforsch. 47a, 753—760 (1992); received January 20 1992 
  Published    1992 
  Keywords    Alkali halides, Melting curves, Energy criterion, Entropy criterion, Ross's criterion 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0753.pdf 
 Identifier    ZNA-1992-47a-0753 
 Volume    47 
3Author    V. A. Khokhlov, A. O. Kodintseva, E. S. FilatovRequires cookie*
 Title    "Anomalous" Thermal Conductivity of Crystalline Alkali Halides Close to Their Melting Point  
 Abstract    The thermal conductivity of crystalline alkali halides MX (M = Li, Na, K, Rb, and Cs; X = C1, Br, and I) close to their melting point has been measured by the steady-state coaxial-cylinders method. It was found to change anomalously as the temperature varied. A minimum of the thermal conduc-tivity at a characteristic temperature depends on the ionic composition of the crystal. This effect is ascribed to the formation of cooperating defects in the melting lattice. An expression relating the thermal conductivity of the ionic crystal near the melting point to the concentration of these defects is proposed. 
  Reference    Z. Naturforsch. 48a, 595—598 (1993); received April 25 1992 
  Published    1993 
  Keywords    Thermal conductivity, High temperature, Melting point, Ionic crystal, Alkali halide 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0595.pdf 
 Identifier    ZNA-1993-48a-0595 
 Volume    48 
4Author    Masahisa KakiuchiRequires cookie*
 Title    Hydrogen Isotope Fractionation in Aqueous Alkali Halide Solutions  
 Abstract    The D/H ratios of hydrogen gas in equilibrium with aqueous alkali halide solutions were deter-mined at 25 °C, using a hydrophobic platinum catalyst. The hydrogen isotope effect between the solution and pure water changes linearly with the molality of the solution at low concentrations, but deviates from this linearity at higher concentration for all alkali halide solutions. The magnitude of the hydrogen isotope effect is in the order; Kl > Nal > KBr > CsCl ^ NaBr > KCl > NaCl > LiCl, at concentrations up to a molality of 4 m. The sign and trend of the hydrogen isotope effect is different from that of oxygen. In aqueous alkali halide solutions, the hydrogen isotope effect is influenced by both the cation and the anion species, while the oxygen isotope effect is mainly caused by the cation species. This suggests that the mechanism of hydrogen isotope fractionation between the water molecules in the hydration spheres and the free water molecules differs from the mechanism of the oxygen isotope fractionation. The hydrogen and oxygen isotope effects for alkali halides, except LiCl and NaCl, may be influenced by changes in energy of the hydrogen bonding in free water molecules. 
  Reference    Z. Naturforsch. 52a, 811—820 (1997); received April 15 1997 
  Published    1997 
  Keywords    Hydrogen Isotope, Alkali halide, D/H fractionation, Thermodynamics, Isotope effect 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0811.pdf 
 Identifier    ZNA-1997-52a-0811 
 Volume    52