Novel low loss and temperature stabilized (Na_1-xLi_x)_0.5(Sm_1-xBix)_0.5MoO₄(x = 0.05−0.2) microwave ceramics for low-temperature cofired ceramic technology

This study focused on achieving low loss and temperature stabilized microwave dielectric ceramics. A novel scheelite structured (Na_1-xLi_x)_0.5(Sm_1-xBi_x)_0.5MoO₄(NLSBMx, where x = 0.05−0.2) ceramics with the excellent microwave dielectric properties at low sintering temperatures. The structural influences on dielectric behavior were systematically explored through X-ray diffraction (XRD), Raman spectroscopy, and microstructure analysis. Results confirmed that the NLSBMx (x = 0.05−0.2) ceramics crystallize in a pure tetragonal scheelite structure. The NLSBMx system exhibited exceptional performance at low sintering temperatures (675−900 °C), with ε_rvalues of 11.6–14.6, Q × f values of 38,900−17,700 GHz, and τ_fvalues ranging from −35.5 to +2.7 ppm/°C. Notably, the NLSBM0.15 ceramic sintered at 825 °C demonstrated optimal properties: ε_r∼13.5, Q × f ∼23,000 GHz (at 9.03 GHz), and τ_f ∼ −10.4 ppm/°C. Using the Phillips-Vechten-Levine (P-V-L) chemical bond theory, bond ionicity (f_i), lattice energy (U), and thermal expansion coefficient (α_L) were calculated. The Mo–O bonds exhibited higher f_iand U, indicating their dominant role in enhancing dielectric performance. Additionally, the A–O bonds (A = Na/Li/Sm/Bi) were found to positively influence the properties of the NLSBMx system. The chemical compatibility of NLSBMx (x = 0.05−0.2) ceramics with silver electrodes makes it a potential material for applications in low-temperature co-fired ceramic (LTCC) technology for 5G/6G communication systems.