Phase equilibria and crystal chemistry of the CaO–½Sm₂O₃–CoOz system at 885 °C in air

Journal Article · Sat Jun 27 00:00:00 EDT 2015 · Solid State Sciences

DOI:https://doi.org/10.1016/j.solidstatesciences.2015.06.003· OSTI ID:1245143

Wong-Ng, W. ^[1]; Laws, W. ^[2]; Lapidus, S. H. ^[3]; Kaduk, J. A. ^[4]

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1. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
2. Univ. of Maryland, College Park, MD (United States). Dept. of Chemistry and Biochemistry
3. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
4. Illinois Inst. of Technology, Chicago, IL (United States)

The CaO–½Sm₂O₃–CoOz system prepared at 885 °C in air consists of two calcium cobaltate compounds, namely, the 2D thermoelectric oxide solid solution, (Ca_3$$-$$xSm_x)Co₄O_9$$-$$z (0 ≤ x ≤ 0.5) which has a misfit layered structure, and the 1D Ca₃Co₂O₆ which consists of chains of alternating CoO₆ trigonal prisms and CoO₆ octahedra. Ca₃Co₂O₆ was found to be a point compound without the substitution of Sm on the Ca site. A solid solution region of distorted perovskite, (Sm_1$$-$$xCa_x)CoO_3$$-$$z (0 ≤ x ≤ 0.22, space group Pnma) was established. The reported Sm₂CoO₄ phase was not observed at 885 °C, but a ternary Ca-doped oxide, (Sm_1+xCa_1$$-$$x)CoO_4$$-$$z (Bmab) where 0 < x ≤ 0.15 was found to be stable at this temperature. In the peripheral binary systems, Sm was not present in the Ca site of CaO, while a small solid solution region was identified for (Sm_1$$-$$xCa_x)O(3_$$-$$z)/2 (0 ≤ x ≤ 0.075). Lastly, ten solid solution tie-line regions and six three-phase regions were determined in the CaO–½Sm₂O₃–CoO_z system in air.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1245143
• Alternate ID(s): OSTI ID: 1251268
• Journal Information: Solid State Sciences, Vol. 48, Issue C; ISSN 1293-2558
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Phase diagram of CaO-½Sm2O3-CoOz
structure for (Sm1-xCax)2O3-z, and (Sm1+xCa1-x)CoO4-z
thermoelectric oxide system
tie-line phase relationships