Abstract
A new method of calculation of melting temperatures of binary ionic crystals has been suggested. The method is based on finding a matrix relation between the ionic radii (the lattice energy U) and melting temperature of ionic crystals of the MX type, where M is a Group 1A metal, and X is a halogen. From the equation for the lattice energy U, a new equation has been derived for calculation of the melting temperature of ionic crystals with the use of only the ionic radii and the degree of bond ionicity ɛ: T m = f(U, ɛ). The average error of determination of T m for alkali-metal halides is 2.80%. The melting temperatures of francium halides and alkali-metal astatides (including FrAt) have been calculated. It has been shown that the accuracy of calculation of the melting temperature of ionic crystals depends on the degree of bond ionicity: the error increases with an increase in the covalent contribution. On the basis of the melting temperatures of metal halide crystals, a method has been developed for the calculation of the melting temperatures of corresponding metals. The melting temperature of francium has been calculated to be 24.861 ± 0.517°C.
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Original Russian Text © V.V. Oshchapovskii, 2014, published in Zhurnal Neorganicheskoi Khimii, 2014, Vol. 59, No. 6, pp. 738–745.
Part IV. See V.V. Oshchapovskii, Russ. J. Gen. Chem. 78, 532 (2008); Russ. J. Inorg. Chem. 55, 401 (2010); Russ. J. Inorg. Chem. 57, 211 (2012).
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Oshchapovskii, V.V. A new method of calculation of the melting temperatures of crystals of Group 1A metal halides and francium metal. Russ. J. Inorg. Chem. 59, 561–567 (2014). https://doi.org/10.1134/S0036023614060163
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DOI: https://doi.org/10.1134/S0036023614060163