Improved structure and temperature stabilities in Sm ₂ O ₃ ceramics using ion radius strategy

Abstract The cracking behavior and significant + τ f value have limited the application of Sm 2 O 3 ceramics, which possess excellent microwave dielectric properties. In this study, La‐ and Dy‐substituted Sm 2 O 3 ceramics were prepared by the one‐step sintering method. Both Sm 2− x La x O 3 and Sm 2− x Dy x O 3 (0≤ x ≤0.65) ceramics exhibited a monoclinic structure. La and Dy ions can promote the grain growth and abnormal development of Sm 2 O 3 ceramics. Cracks were observed on the surfaces and fracture sections of the Sm 2− x La x O 3 (0≤ x ≤0.65) ceramics, and these with low Dy contents, which are attributed to the chemical nature of Sm 2 O 3 and La 2 O 3 , as well as the lattice strain proven by the bond strain index ( BSI ) and global instability index ( GII ). With the increase of the substitution amounts of La and Dy, the increased τ ε value plays a dominant role in manipulating the τ f value of these Sm 2 O 3 ‐based ceramics to a near‐zero level. The stabilized structure is achieved in Sm 1.35 Dy 0.65 O 3 ceramic, which exhibits attractive microwave dielectric properties: ε r = 22.2, Q× f = 21 750 GHz, and τ f = +3.1 ppm/°C. These results suggest that introducing rare earth ions with different ionic radii could stabilize the structure of Sm 2 O 3 ceramics and tune their performance.