Phase relations in the system Cu-Ho-O and stability of Cu{sub 2}Ho{sub 2}O{sub 5}

Journal Article · Sat Jan 01 00:00:00 EST 1994 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1994.tb06966.x· OSTI ID:142243

Matthews, T; Jacob, K T ^[1]

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1. Indian Inst. of Science, Bangalore (India). Dept. of Metallurgy

The phase relations in the system Cu-Ho-O have been determined at 1300 K using X-ray diffraction, optical microscopy, and electron microprobe analysis of samples equilibrated in evacuated quartz ampules and in pure oxygen. Only one ternary compound, Cu{sub 2}Ho{sub 2}O{sub 5}, was found to be stable. The Gibbs free energy of formation of this compound has been measured. Since the formation is endothermic, Cu{sub 2}Ho{sub 2}O{sub 5} becomes thermodynamically unstable with respect to CuO and Ho{sub 2}O{sub 3} below 810 K. When the oxygen partial pressure over Cu{sub 2}Ho{sub 2}O{sub 5} is lowered, it decomposes. The decomposition temperature at an oxygen partial pressure of 1.52 X 10{sup 4} Pa was measured using a combined DTA-TGA apparatus. Based on these results, an oxygen potential diagram for the system Cu-Ho-O at 1300 K is presented.

• Sponsoring Organization: USDOE
• OSTI ID: 142243
• Journal Information: Journal of the American Ceramic Society, Vol. 77, Issue 1; Other Information: PBD: Jan 1994
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COPPER OXIDES
PHASE STUDIES
HOLMIUM OXIDES
EXPERIMENTAL DATA
PHASE DIAGRAMS
HIGH-TC SUPERCONDUCTORS