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Energetics of Substituted Pollucites Along the CsAlSi 2 O 6 –CsTiSi 2 O 6.5 Join: A High‐Temperature Calorimetric Study
Author(s) -
Xu Hongwu,
Navrotsky Alexandra,
Balmer Mari Lou,
Su Yali,
Bitten Eric R.
Publication year - 2001
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2001.tb00697.x
Subject(s) - endothermic process , standard enthalpy of formation , exothermic reaction , boron , thermochemistry , thermodynamics , calorimetry , standard enthalpy change of formation , chemistry , energetics , drop (telecommunication) , lattice energy , mineralogy , analytical chemistry (journal) , crystal structure , crystallography , adsorption , computer science , chromatography , telecommunications , physics , organic chemistry
Enthalpies of drop solution for a suite of substituted pollucites with the compositions CsTi x Al 1− x Si 2 O 6+0.5 x , 0 ≤ x ≤ 1, which are synthesized using the sol–gel method, have been measured in molten lead borate (2PbO·B 2 O 3 ) at 701°C. As Ti 4+ substitutes for Al 3+ , the enthalpies of drop solution become less endothermic and show exothermic heats of mixing within the composition range from x = 0.3 to 1. This nonideal mixing behavior is consistent with the trend seen in variation of lattice parameters, and we interpret it to be a result of the short‐range order associated with the framework cations Al 3+ , Si 4+ , and Ti 4+ in the structure. Using enthalpies of drop solution of SiO 2 , Al 2 O 3 , TiO 2 , and Cs 2 O, standard molar enthalpies of formation of these phases from their constituent oxides and from the elements are derived for the first time.