Structure, microwave dielectric properties, Raman spectra and P-V-L theory of La3+ substituted Nd2[Zr0.89(Bi0.5Ta0.5)0.11]3(MoO4)9 ceramics

With the rapid development of 5G/6G mobile communication technology, microwave dielectric materials are facing increasingly strict performance requirements. As core fundamental materials for modern communication systems, performance optimization of microwave dielectric ceramics has become a research hotspot. Addressing the limitations of single-phase ceramic materials, dense microwave dielectric ceramics of (Nd _1 − x La _x ) ₂ [Zr _0.89 (Bi _0.5 Ta _0.5 ) _0.11 ] ₃ (MoO ₄ ) ₉ (x = 0.01, 0.03, 0.05, 0.07) were prepared by the conventional solid-state reaction method. The experimental process involved 550°C pre-sintering followed by gradient sintering at 600–725°C (4h holding time). X-ray diffraction (XRD) analysis confirmed that all samples exhibited trigonal crystal structure with R3c space group. The lattice parameters were obtained by Rietveld refinement method. Scanning Electron Microscopy (SEM) characterization indicates that compactness has a significant impact on the dielectric constant (ε _r ) and the quality factor (Q×f). Raman spectroscopy analysis indicated strong associations of ε _r and Q×f values with characteristic peak shifts and full width at half maximum (FWHM), respectively. When sintered at 675°C, the NLZBTM (x = 0.03)ceramics exhibited exceptional comprehensive performance: ε _r  = 11.24 ± 0.02, Q×f = 116914 ± 5738 GHz, and τ _f =-37 ± 1.5 ppm/℃. The bond property analysis based on the P-V-L theory shows that the ionicity of the Nd/La-O bond makes the greatest contribution to ε _r , while the covalency of the Mo-O bond significantly affects the Q×f value and τ _f parameter. It is noteworthy that this material achieves low-temperature sintering at 675°C while maintaining excellent microwave dielectric properties, demonstrating significant potential as a candidate material for low-temperature co-fired ceramics (LTCC).