Non-Congruence Of High-Temperature Mechanical And Structural Behaviors Of Lacoo3 Based Perovskites

Keywords

Hysteresis; Lanthanum cobaltite; Powder diffraction; Raman spectroscopy; Temperature dependence; Young's modulus

Abstract

This paper presents the mechanical behavior of LaCoO3 and La0.8Ca0.2CoO3 ceramics under four-point bending in which the two cobaltites are subjected to a low stress of ∼8 MPa at temperatures ranging from room temperature to 1000 °C. Unexpected stiffening is observed in pure LaCoO3 in the 700–900 °C temperature range, leading to a significant increase in the measured Young's modulus, whereas La0.8Ca0.2CoO3 exhibits softening from 100 °C to 1000 °C, as expected for most materials upon heating. Neutron diffraction, X-ray diffraction and micro-Raman spectroscopy are used to study the crystal structure of the two materials in the RT–1000 °C temperature range. Despite a detailed study, there is no conclusive evidence to explain the stiffening behavior observed in pure LaCoO3 as opposed to the softening behavior in La0.8Ca0.2CoO3 at high temperatures (above 500 °C).

Publication Date

4-1-2017

Publication Title

Journal of the European Ceramic Society

Volume

37

Issue

4

Number of Pages

1563-1576

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.jeurceramsoc.2016.11.005

Socpus ID

85007303691 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85007303691

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