High-entropy effect on the electrical properties and aging stability of lanthanum aluminate ceramics

Abstract

High-entropy ceramics display superior properties owing to their elevated group entropy, which arises from the occupancy of lattice sites by multiple primary elements. In this study, the increase in the linearity and thermal stability of the temperature-resistance profiles is achieved through the doping of high-entropy oxides at the B-position in lanthanum aluminate, leading to increased entropy, which affects the La‒O and Al‒O bond lengths and influences the distortion of the AlO₆ octahedra. Additionally, the heterogeneous arrangement of cations with varied valence states at the B position contributes to a high dislocation density after doping with high-entropy oxides. Furthermore, this material demonstrates temperature-dependent characteristics within a temperature range of 673‒1673 K and features high measurement precision (R² reaching 99.858% and residual sum of squares as minimal as 0.255). Most notably, the material shows exceptional thermal stability, with an aging coefficient below 1% for a 0.1 concentration of high-entropy oxide doped after enduring 1000 h at 1273 K. This research provides a promising approach for the development of high-temperature thermal ceramics characterized by enhanced resistance temperature linearity and robust stability, catering to the stringent demands of advanced high-temperature measurement technologies.