Crystal structure analysis and high‐temperature phase transitions of complex rare‐earth perovskite, La2(Al1/2MgTa1/2)O6.
Saved in:
| Title: | Crystal structure analysis and high‐temperature phase transitions of complex rare‐earth perovskite, La |
|---|---|
| Authors: | Sohn, Yoo Jung1 (AUTHOR) y.sohn@fz-juelich.de, Mauer, Georg1 (AUTHOR), Roth, Georg2 (AUTHOR), Guillon, Olivier1,3 (AUTHOR), Vaßen, Robert1 (AUTHOR) |
| Source: | Journal of the American Ceramic Society. Feb2020, Vol. 103 Issue 2, p1404-1413. 10p. 4 Diagrams, 2 Charts, 4 Graphs. |
| Subjects: | Phase transitions, Crystal structure, Thermal barrier coatings, Rare earth metals, Symmetry groups, Rietveld refinement |
| Abstract: | 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 R3¯. On further heating, LAMT transforms to the ideal cubic phase at ~1390°C with the space group symmetry Fm3¯m. 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. [ABSTRACT FROM AUTHOR] |
| Copyright of Journal of the American Ceramic Society is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
|
Full text is not displayed to guests.
Login for full access.
|
|
| Abstract: | 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 R3¯. On further heating, LAMT transforms to the ideal cubic phase at ~1390°C with the space group symmetry Fm3¯m. 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. [ABSTRACT FROM AUTHOR] |
|---|---|
| ISSN: | 00027820 |
| DOI: | 10.1111/jace.16740 |
