Crystal structure, chemical bond features and microwave dielectric properties of novel KBaLnMo3O12 (Ln = Eu, Yb) ceramics

The exploration of high-performance microwave dielectric ceramics exhibiting low-permittivity is of great significance for the advancement of next-generation wireless communication technologies. To meet the demands of the growing field of wireless communication, two novel low-permittivity KBaLnMo 3 O 12 (Ln = Eu, Yb; named KBEM and KBYM) ceramics with monoclinic structure were synthesized using a solid-state reaction route. Good microwave dielectric properties of ε r = 8.54, Q  ×  f = 30, 611 GHz, and τ f = −45.2 ppm/°C were achieved for KBEM sintered at 790 °C, and KBYM sintered at 810 °C possessed excellent microwave dielectric properties of ε r  = 8.87, Q  ×  f = 52, 241 GHz, and τ f = −34.9 ppm/°C. According to the bond valence result, K + and Ba 2+ presented a strong compressed state but most Mo 6+ exhibited a slightly rattling state in both ceramics. The higher packing fraction and lattice energy might be the main reason for the higher Q  ×  f in KBYM. The Mo–O bond in both ceramics played a vital role in influencing the Q  ×  f according to the Phillips−Van Vechten−Levine (P−V−L) theory. Furthermore, KBaLnMo 3 O 12 (Ln = Eu, Yb) ceramics show good chemical compatibility with Ag powders and are suitable for low temperature co-fired ceramic (LTCC) applications.