TY  - JOUR
AU  - Sohn, Yoo Jung
AU  - Mauer, Georg
AU  - Roth, Georg
AU  - Guillon, Olivier
AU  - Vaßen, Robert
TI  - Crystal structure analysis and high‐temperature phase transitions of complex rare‐earth perovskite, La 2 (Al 1/2 MgTa 1/2 )O 6
JO  - Journal of the American Ceramic Society
VL  - 103
IS  - 2
SN  - 1551-2916
CY  - Westerville, Ohio
PB  - Soc.
M1  - FZJ-2019-04985
SP  - 1404-1413
PY  - 2020
AB  - In situ high‐temperature powder X‐ray diffraction analysis (HT‐XRD) was carried out in the temperature range from 25°C‐1430°C to investigate the crystal structure of double perovskites, La2(Al1/2MgTa1/2)O6 (LAMT) and its phase transitions. This complex perovskite is a promising candidate for application in thermal barrier coating systems. Rietveld analysis shows a rock‐salt type ordering of the B‐site cations in the monoclinic space group symmetry, P21/n at room temperature. Upon heating, a structural phase transition occurs at ~855°C, and the crystal structure becomes rhombohedral with the space group symmetry urn:x-wiley:00027820:media:jace16740:jace16740-math-0001. On further heating, LAMT transforms to the ideal cubic phase at ~1390°C with the space group symmetry urn:x-wiley:00027820:media:jace16740:jace16740-math-0002. Both of the structural phase transitions are completely reversible, and were confirmed through complementary differential scanning calorimetry and thermogravimetry measurements. With increasing temperature, the degree of the octahedral tilting decreases and the variance of the different B–O bond lengths is reduced, until in the cubic phase, no tilting is present, and almost equal B–O bond lengths are obtained.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000486945300001
DO  - DOI:10.1111/jace.16740
UR  - https://juser.fz-juelich.de/record/865634
ER  -