| Autor: |
Tomaszewski, P. E., Miniajluk, N., Zawadzki, M., Trawczyński, J. |
| Předmět: |
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| Zdroj: |
Phase Transitions; Jun2019, Vol. 92 Issue 6, p525-536, 12p |
| Abstrakt: |
The nanocrystalline LaMnO3+δ perovskite was synthesized by the microwave-assisted glycothermal method and calcined at several temperatures up to 1500°C. The prepared samples were examined by the X-ray powder diffraction with the aim to show that LaMnO3+δ exhibits the size-induced structural phase transitions. The as-received nanocrystals of LaMnO3+δ are of tetragonal, pseudo-cubic symmetry not known for bulk material. The samples calcined at temperatures 750–1100°C have trigonal symmetry known from the high-temperature phase of LaMnO3 single crystal. The samples calcined from 1200°C to 1500°C have two phases: trigonal and orthorhombic. Thus, the observed phase sequence is inverted with respect to that of the bulk material, which is the characteristic of the size-induced mechanism of phase transitions in the nanocrystals. The critical crystallite sizes for both structural transitions were evaluated as 20 and 100 nm. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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