La2Hf2O7 crystal and local structure changes on the fluorite - pyrochlore phase transition

2nd Conference on Plasma & Laser Research and Technologies

Popov, V.V.^1,2 ; Menushenkov, A.P.^1 ; Yastrebtsev, A.A.^1 ; Zubavichus, Ya V.^2

National Research Nuclear University MEPhI, Moscow Engineering Physics Institute, Kashirskoe sh. 31, Moscow

115409, Russia^1

NRC, Kurchatov Institute, pl. Akademika Kurchatova 1, Moscow

123182, Russia^2

关键词: Calcinations temperature;    Fluorite structure;    Formation and evolutions;    Nucleation and growth;    Pyrochlore phase;    Synchrotron radiation x-ray diffractions;    Temperature range;    X-ray amorphous;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/747/1/012043/pdf
DOI  :  10.1088/1742-6596/747/1/012043

来源: IOP

【 摘 要 】

The process of La2Hf2O7(rLa3+/rHf4+= 1.63) nanocrystals formation and evolution upon calcinations up to 1400 °C has been investigated by means of synchrotron radiation X-ray diffraction (XRD) and Raman spectroscopy. It has been shown that isothermal calcination at 800 °C/3h of the X-ray amorphous precursor firstly leads to the formation of oxide nanocrystalline powders with a defect fluorite structure. In the temperature range 900 - 1000 °C we observed the nucleation and growth of pyrochlore nanodomains inside a well crystalline fluorite matrix. The pyrochlore-type superstructural ordering of cations and anions appears at calcinations temperature higher than 1000 °C.