TY - JOUR
T1 - Co 3O 4-Co 2ZnO 4 spinels
T2 - The case for a solid solution
AU - Perry, Nicola H.
AU - Mason, Thomas O.
AU - Ma, Chengcheng
AU - Navrotsky, Alexandra
AU - Shi, Yezhou
AU - Bettinger, Joanna S.
AU - Toney, Michael F.
AU - Paudel, Tula R.
AU - Lany, Stephan
AU - Zunger, Alex
N1 - Funding Information:
This work was supported by the ''Center for Inverse Design,'' an Energy Frontier Research Center funded by the Office of Basic Energy Sciences, U.S. Department of Energy, under Grant No. DE-AC36-08GO28308. CM and AN acknowledge funding from DOE Basic Energy Sciences grant DE-FG02-05ER15667 . The X-ray diffraction work was conducted in the J. B. Cohen X-Ray Diffraction Facility supported by the MRSEC program of the National Science Foundation (Grant No. DMR-0520513 ) at the Materials Research Center of Northwestern University. The anomalous X-ray diffraction work was carried out at the Stanford Synchrotron Radiation Lightsource, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. We acknowledge the support of the National Institute of Standards and Technology, U. S. Department of Commerce, in providing the neutron research facilities used in this work. YS, JSB, and MFT are grateful to Dr. Mark Green for his help with data collection and discussion about data refinement.
PY - 2012/6
Y1 - 2012/6
N2 - In prior first-principles theoretical work we predicted a complete solid solution in the Co 3O 4-Co 2ZnO 4 system, with a negligibly small mixing enthalpy. In this work we tested this prediction on bulk, large-grained specimens across the Co 3O 4-Co 2ZnO 4 join, combining oxide melt solution calorimetry, differential scanning calorimetry, precise lattice parameter measurements, anomalous X-ray and neutron diffraction, and in situ electrical measurements. The calorimetric results confirm the presence of a solid solution at high temperatures, but with a large enthalpy of mixing that exceeds the predicted value. Because Co 3O 4 and Co 2ZnO 4 have essentially identical lattice parameters, this energetic destabilization must arise from factors other than the strain energy resulting from size mismatch. Changes in Co 3 spin states vs. temperature and zinc content are proposed to account for the positive excess enthalpy, and may also provide additional entropy to stabilize the solid solution at high temperature.
AB - In prior first-principles theoretical work we predicted a complete solid solution in the Co 3O 4-Co 2ZnO 4 system, with a negligibly small mixing enthalpy. In this work we tested this prediction on bulk, large-grained specimens across the Co 3O 4-Co 2ZnO 4 join, combining oxide melt solution calorimetry, differential scanning calorimetry, precise lattice parameter measurements, anomalous X-ray and neutron diffraction, and in situ electrical measurements. The calorimetric results confirm the presence of a solid solution at high temperatures, but with a large enthalpy of mixing that exceeds the predicted value. Because Co 3O 4 and Co 2ZnO 4 have essentially identical lattice parameters, this energetic destabilization must arise from factors other than the strain energy resulting from size mismatch. Changes in Co 3 spin states vs. temperature and zinc content are proposed to account for the positive excess enthalpy, and may also provide additional entropy to stabilize the solid solution at high temperature.
KW - Calorimetry
KW - Co O
KW - Diffraction
KW - Electrical conductivity
KW - Mixing thermodynamics
KW - ZnCo O
UR - http://www.scopus.com/inward/record.url?scp=84860723607&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84860723607&partnerID=8YFLogxK
U2 - 10.1016/j.jssc.2012.02.022
DO - 10.1016/j.jssc.2012.02.022
M3 - Article
AN - SCOPUS:84860723607
SN - 0022-4596
VL - 190
SP - 143
EP - 149
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
ER -