Electrical conductivity of La0.58Sr0.4Co0.2Fe0.8O3 − δ during ferroelastic deformation under uniaxial compressive loading

In the present study, electrical conductivity of lanthanum strontium cobalt ferrite oxide and its relationship to ferroelastic deformation were examined under uniaxial compressive loading at elevated temperatures up to 1073 K. The conductivity increases with increasing compressive stress at all temperatures. The increase in conductivity can be related to both geometrical and piezoelectric effects. From 293 K to 873 K, where the material exhibits ferroelastic behaviour, the variation in the total conductivity decreases with increasing temperature. The contribution of the piezoelectric effect to the total conductivity variation also decreases with increasing temperature and the maximum in piezoconductivity has a value of about 0.75% at 293 K for a compressive stress of 100 MPa. There is no effect of ferroelastic domain switching on the conductivity except for the geometric effect. At 1073 K, where the ferroelastic characteristic almost disappears and the high-temperature creep behaviour appears, the conductivity is simply proportional to the compressive strain. The present results also indicate a possibility to use this material as strain sensor at elevated temperatures.