Decomposition of La2−xSrxCuO4 into several La2O3 phases at elevated temperatures in ultrahigh vacuum inside a transmission electron microscope

Jong Seok Jeong, Wangzhou Wu, Mehmet Topsakal, Guichuan Yu, Takao Sasagawa, Martin Greven, K. Andre Mkhoyan

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Abstract

We report the decomposition of La2-xSrxCuO4 into La2O3 and Cu nanoparticles in ultrahigh vacuum, observed by in situ heating experiments in a transmission electron microscope. The analysis of electron diffraction data reveals that the phase decomposition process starts at about 150 °C and is considerably expedited in the temperature range of 350 °C-450 °C. Two major resultant solid phases are identified as metallic Cu and La2O3 by electron diffraction, simulation, and electron energy-loss spectroscopy (EELS) analyses. With the aid of calculations, La2O3 phases are further identified to be derivatives of a fluorite structure - fluorite, pyrochlore, and (distorted) bixbyite - characterized by different oxygen-vacancy order. Additionally, the bulk plasmon energy and the fine structures of the O K and LaM4,5 EELS edges are reported for these structures, along with simulated O K x-ray absorption near-edge structure. The resultant Cu nanoparticles and La2O3 phases remain unchanged after cooling to room temperature.

Original languageEnglish (US)
Article number054801
JournalPhysical Review Materials
Volume2
Issue number5
DOIs
StatePublished - May 15 2018

How much support was provided by MRSEC?

  • Partial

Reporting period for MRSEC

  • Period 5

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