La3+-substituted Nd2[Zr0.89(Bi0.5Ta0.5)0.11]3(MoO4)9 ceramics: structure, dielectric properties, Raman analysis, and P–V–L theory

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 (4 h holding time). X-ray diffraction (XRD) analysis confirmed that all samples exhibited trigonal crystal structure with \(R\overline{3} c\) 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  = 116,914 ± 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 εᵣ , 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).