Effect of Loading and Heating History on Deformation of LaCoO3.

Mykola Lugovy,Jakob Kuebler,Gurdial Blugan,Dmytro Verbylo,Nina Orlovskaya,Michael Reece,Thomas Graule

doi:10.3390/ma14133543

Abstract

The aim of this work was to study cyclic stress–strain deformation behavior of LaCoO3 as a function of loading and heating history. The ferroelastic hysteretic deformation of LaCoO3 at different stresses and temperatures was characterized using effective Young’s modulus, hysteresis loop area and creep strain shift parameters. The deformation behavior of LaCoO3 was not significantly affected by the previous loading and heating history when tested at constant temperature. The high temperature strength and Young’s modulus of LaCoO3 were higher compared to at room temperature. A creep strain shift parameter was introduced to characterize creep strain in LaCoO3 for the first time.

Highlights

The deformation behavior of LaCoO3 -based ceramics has been studied in great detail in the past [1,2,3,4,5,6,7,8]
An attempt was made to understand the effect of loading and heating history on the ferroelastic hysteretic behavior of LaCoO3 perovskite
It was established that elevated temperatures have a significant effect on stress–strain deformation, hysteresis, and creep of LaCoO3 upon cycling, which is consistent with previously reported results

Summary

Introduction

The deformation behavior of LaCoO3 -based ceramics has been studied in great detail in the past [1,2,3,4,5,6,7,8]. It is well established that unlike many other ceramics, such as B4 C, Si3 N4 , SiC, or Al2 O3 , LaCoO3 -based perovskites exhibit nonlinearity, ferroelasticity, and hysteresis upon mechanical loading [1,2]. An attempt to explain the unusual high temperature stiffening by a possible high temperature phase transition of the LaCoO3 crystal lattice was not fruitful, as high-resolution neutron diffraction clearly showed that the crystal structure of LaCoO3 remains R3c rhombohedral and only a thermal expansion of the lattice was detected upon heating It was not clear how an expanding lattice with associated increasing bond lengths upon heating could contribute to a significant increase of the Young’s modulus and stiffening of LaCoO3. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations

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