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High‐Temperature Energy Relations in the Alkali Borates: Binary Alkali Borate Compounds and Their Glasses

1961; Wiley; Volume: 44; Issue: 2 Linguagem: Inglês

10.1111/j.1151-2916.1961.tb15353.x

1551-2916

G. SHERWOOD SMITH, Guy E. Rindone,

Chemical Synthesis and Characterization

The energy relations existing between the congruently melting compounds Li 2 O ‐2B 2 O 3 , Na 2 O–2B 2 O 3 , Na 2 O‐4B 2 O 3 , and K 2 O‐4B 2 O 3 and their glasses have been determined for the temperature range 25° to 1100°C. High‐temperature heat‐content, entropy, and heat of solution data are given for both the glasses and the corresponding devitrified materials. A comparison of the heats of fusion of the alkali borates on a gram atom of oxygen basis shows that they follow the order Li > Na > K. The entropy differences between the glass and the corresponding crystalline material have been determined at 25°C. The free‐energy change at 25°C. for the reaction crystal → glass has been calculated for the four compounds.