Single-Ion Magnetostriction in Gd2O3-CeO2 Solid Solutions

Ceria (CeO2) and its solid solutions with Gd2O3 are technologically important and environmentally friendly materials with numerous interesting properties and important applications. Nevertheless, the magnetic properties of ceria are even today not fully understood, and magnetoelastic coupling in pure or doped ceria remains essentially unexplored. This has been so, in part, due to the difficulty of measuring very small magnetostrictive strains in weakly paramagnetic materials. During the last decade, however, technical advances have enabled sensitive and accurate measurements of sample deformation in high magnetic fields. Here, forced magnetostriction (MS) in Gd2O3-CeO2 solid solution ceramics (Ce1-xGdxO2-x/2, 0 <= x <= 1) at room temperature is characterized. In a pulsed magnetic field mu H-0 <= 60 Tesla, longitudinal MS strain is observed to depend on the square of the field amplitude and to increase linearly with Gd3+ concentration but is not sensitive to the lattice symmetry of the ceramics. The theory attributes the origin of the observed strain to the single-ion MS response of Gd3+ to the crystal field via mixing of ground and excited electronic states and covalent hybridization with oxygen ligands. Contributions of charge-compensating oxygen vacancies and/or Van Vleck paramagnetism to the observed magnetoelastic coupling are determined to be negligible.

Automated summary

Ceria and its solid solutions with Gd2O3 are important materials with interesting properties and various applications. However, the understanding of ceria's magnetic properties and magnetoelastic coupling is still limited. In this study, forced magnetostriction in Gd2O3-CeO2 solid solution ceramics is characterized, revealing a linear relationship between strain and Gd3+ concentration. The observed strain is attributed to the single-ion magnetostrictive response of Gd3+ to crystal field.