Micro-structure and microwave dielectric properties of Cerium oxide with Nd/Y diatomic substitution

Cerium oxide (CeO 2 ) ceramics with neodymium/yttrium (Nd/Y) diatomic substitution had been prepared, aiming at exploring the relationships between structures and microwave dielectric properties. After substitution, the CeO 2 ceramics were still indexed as a pure CeO 2 phase belonged to Fm-3 m (225) group, meanwhile, the Nd/Y ions showed disorderly distributions to occupy the position of cerium atoms (Ce) since no superlattice diffraction peak was detected. The cell volume of the substituted CeO 2 ceramics changed regularly with the changing ratio of Nd/Y ions owing to the different ion radii of Nd and Y ions. The surface structure had been characterized by grain size, which dropped sharply when the atomic ratio of Nd/Y changed from 4:1 to 3:2, and then tended to level off. The dielectric constant ( ε r ) of the ion-substituted CeO 2 ceramics, which was mainly affected by porosity, polarizability, and defects, changed from 20.78 to 22.02 with different Nd/Y ratios. The quality factor ( Q × f ) values of the substituted CeO 2 ceramics, which determined by packing fraction, grain size, and relative density, increased from 40,000 GHz to 77,000 GHz when the Nd/Y ratio changed from 4:1 to 1:4. The temperature coefficient of resonance frequency ( τ f ) of the substituted CeO 2 ceramics increased with the increasing of Y ion ratio, and the variation trend was consistent with the trend of crystal lattice energy.