Combined experimental and ab initio based determination of the thermal expansion of La0.5Sr0.5Co0.25Fe0.75O3. Issue 7 (24th January 2018)

• Record Type: Journal Article
• Authors: Yin, Xiaoyan; Beez, Alexander; Menzler, Norbert H.; Spatschek, Robert
• Is Part Of: Journal of the American Ceramic Society. Volume 101:Issue 7(2018)
• Page Start: 3086
• Page End: 3093
• Publication Date: 2018-01-24
• Subjects: first principles theory -- phonons -- thermal expansion; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.15430
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: The thermal expansion of La0.5 Sr0.5 Co0.25 Fe0.75 O3 (LSCF55) is investigated both by first principles phonon calculations combined with the quasi‐harmonic approximation (QHA) and by experimental approaches. Within the framework of the QHA, the volumetric thermal expansion coefficient of rhombohedral LSCF55 is calculated as α V, GGA = 50.34 × 10 −6 K −1 . For comparison, the lattice expansion and the volume expansion of LSCF55 grain are measured by in situ high‐temperature X‐ray diffractometer (HT‐XRD). An anisotropic thermal expansion of rhombohedral LSCF55 with α a, hex = 10.89 × 10 −6 K −1 and α c, hex = 21.18 × 10 −6 K −1 is obtained. The volumetric thermal expansion coefficient is measured as α V, HT‐XRD = 43.17 × 10 −6 K −1 . In addition, the effectively isotropic expansion coefficients of a polycrystalline LSCF55 bar specimen are measured using a vertical high‐performance thermo‐mechanical analyzer and yield α l, bar specimen = 17.37 × 10 −6 K −1 and α V, bar specimen = 52.11 × 10 −6 K −1 .