Premium
Thermochemistry and Chemical Vapor Transport of In 2 M 3 O 12 ( M = Mo, W)
Author(s) -
Steiner Udo,
Schmidt Marcus,
Schnelle Walter
Publication year - 2014
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201400354
Subject(s) - thermochemistry , monoclinic crystal system , standard enthalpy of formation , chemistry , enthalpy , analytical chemistry (journal) , differential scanning calorimetry , chemical vapor deposition , calorimetry , orthorhombic crystal system , thermodynamics , crystallography , crystal structure , organic chemistry , physics
The standard entropy of compounds In 2 M 3 O 12 ( M = Mo, W) were determined to be S ° 298 = 390 ± 6 ( M = Mo] and S ° 298 = 404 ± 6 J · mol –1 · K –1 ( M = W). The entropies of formation from the binary oxides are Δ S ° R, 298 = 52 J · mol –1 · K –1 ( M = Mo] and Δ S ° R, 298 = 72 J · mol –1 · K –1 ( M = W). Both compounds possess positive enthalpies of formation from the oxides at 298 K and are entropically stabilized. Transition enthalpies of the monoclinic to orthorhombic phase transition were measured for In 2 M 3 O 12 by differential scanning calorimetry. Crystals of In 2 M 3 O 12 (size up to a few mm) were deposited by means of chemical vapor transport along a temperature gradient Δ T = 100 K using transport agent chlorine. Deposition rates are between 0.2 and about 15 mg · h –1 , depending on mean transport temperature and amount of chlorine. Experimental results were compared to predictions by means of thermodynamic modelling. A detailed analysis of the chemical vapor transport behavior was carried out regarding gaseous compounds involved in the transport process, dominant transport reactions and influence of moisture content.