TY - JOUR
T1 - Thermal expansion of LaAlO3 and (La,Sr)(Al,Ta)O3, substrate materials for superconducting thin-film device applications
AU - Chakoumakos, B. C.
AU - Schlom, D. G.
AU - Urbanik, M.
AU - Luine, J.
PY - 1998/2/15
Y1 - 1998/2/15
N2 - The thermal expansion for the perovskite (La,Sr)(Al,Ta)O3, i.e., LSAT, grown from the formulation 0.29(LaAlO3):0.35(Sr2AlTaO6), was determined by Rietveld refinement of neutron powder diffraction data over the temperature range of 15-1200 K. In comparison to LaAlO3 the relative volume thermal expansion is the same, although the cell volume of LSAT is slightly larger. Site occupation refinement for LSAT gives a structural formula of (La0.29(5)Sr0.71(5))A site (Al0.65(1)Ta0.35(1))B site O3. At and below 150 K, LSAT shows a small distortion from cubic symmetry. Unlike the cubic-to-rhombohedral transition (800 K) observed in LaAlO3, the low temperature structural phase transition in LSAT appears to be cubic-to-tetragonal or cubic-to-orthorhombic. The rms displacement of the A site in LSAT is significantly larger than that for LaAlO3, and about half of the difference can be accounted for by a static displacement component.
AB - The thermal expansion for the perovskite (La,Sr)(Al,Ta)O3, i.e., LSAT, grown from the formulation 0.29(LaAlO3):0.35(Sr2AlTaO6), was determined by Rietveld refinement of neutron powder diffraction data over the temperature range of 15-1200 K. In comparison to LaAlO3 the relative volume thermal expansion is the same, although the cell volume of LSAT is slightly larger. Site occupation refinement for LSAT gives a structural formula of (La0.29(5)Sr0.71(5))A site (Al0.65(1)Ta0.35(1))B site O3. At and below 150 K, LSAT shows a small distortion from cubic symmetry. Unlike the cubic-to-rhombohedral transition (800 K) observed in LaAlO3, the low temperature structural phase transition in LSAT appears to be cubic-to-tetragonal or cubic-to-orthorhombic. The rms displacement of the A site in LSAT is significantly larger than that for LaAlO3, and about half of the difference can be accounted for by a static displacement component.
UR - https://www.scopus.com/pages/publications/0000397038
U2 - 10.1063/1.366925
DO - 10.1063/1.366925
M3 - Article
AN - SCOPUS:0000397038
SN - 0021-8979
VL - 83
SP - 1979
EP - 1982
JO - Journal of Applied Physics
JF - Journal of Applied Physics
IS - 4
ER -