Microstructural and electrical changes in Ca _0.9 <i>R</i> _0.1 CeNbMoO ₈ ( <i>R</i> = Y, Sm, Nd, La) ceramics induced by rare‐earth ion doping

Abstract

Abstract Rare‐earth ions doped Ca 0.9 R 0.1 CeNbMoO 8 ( R = Y, Sm, Nd, La) ceramics have been successfully prepared by solid‐state method, and their modifications to the microstructure and electrical properties are also investigated. The rare‐earth ions doped ceramics exhibit the scheelite structure. With the increase in the radius of rare‐earth ions, the lattice distortion and bond interaction will be enhanced, and the consistency of grain size will be reduced. The ceramics exhibit negative temperature coefficient (NTC) thermistor characteristics in the temperature range of 473 K‐1273 K, and the activation energy decreases with the increase of the radius of rare‐earth ions. Rare‐earth ions doping can increase the content of Ce 3+ ions and promote the conductivity of ceramics. Except for Sm 3+ ‐doped ceramics, the high‐temperature aging rate of other ceramics is less than 2%. The existence of some metastable Sm 2+ ions in Sm 3+ ‐doped ceramics not only increases the activation energy, but also reduces the high‐temperature stability of the ceramics.