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Title: Refining sub-solidus phase relations in the systems CaO–RuO{sub 2}–SiO{sub 2} and CaO–RuO{sub 2}–V{sub 2}O{sub 5}

Graphical abstract: - Highlights: • Refined phase relations of the systems CaO–RuO{sub 2}–SiO{sub 2} and CaO–RuO{sub 2}–V{sub 2}O{sub 5}. • Thermodynamic data for ternary oxides are used to compute the phase diagrams. • No quaternary oxides are reported in these systems. • Tie lines are identified by computing free energy change for exchange reactions. • Stability of calcium ruthenates with SiO{sub 2} and V{sub 2}O{sub 5} can be assessed from diagrams. - Abstract: Sub-solidus phase relations in the ternary systems CaO–RuO{sub 2}–SiO{sub 2} and CaO–RuO{sub 2}–V{sub 2}O{sub 5} have been refined using thermodynamic data on calcium ruthenates, silicates and vanadates. Tie lines are established by considering Gibbs energy change for exchange reactions. Quaternary oxides have not been detected in these systems. Because of the relatively large entropy associated with phase transition of Ca{sub 2}SiO{sub 4} from olivine to α′ structure at 1120 K, reversal of one tie line is seen in the system CaO–RuO{sub 2}–SiO{sub 2} between 950 and 1230 K. There is no change in sub-solidus phase relation as a function of temperature in the system CaO–RuO{sub 2}–V{sub 2}O{sub 5}. Since vanadium can exist in several lower oxidation states, the computed sub-solidus phase relations are valid only at highmore » oxygen partial pressures. There is fair agreement between the computed phase diagram and the limited experimental information available for CaO-deficient compositions in the literature.« less
Authors:
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Publication Date:
OSTI Identifier:
22341751
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 48; Journal Issue: 9; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CALCIUM; CALCIUM OXIDES; CALCIUM SILICATES; ELECTRICAL PROPERTIES; ENTROPY; FREE ENERGY; OXYGEN; PARTIAL PRESSURE; PHASE DIAGRAMS; PHASE TRANSFORMATIONS; RUTHENIUM OXIDES; SILICA; SILICON OXIDES; TEMPERATURE DEPENDENCE; VANADATES; VANADIUM OXIDES