Novel Tri-rutile Ni0.5Ti0.5TaO4 Microwave Dielectric Ceramics: Crystal Structure Chemistry, Raman Vibration Mode, and Chemical Bond Characteristic In-Depth Studies

Abstract

Here, a novel tri-rutile Ni0.5Ti0.5TaO4 ceramic configuration was first reported, and the sintering features, chemical bond theory, and microwave dielectric properties were systematically explored. Pure Ni0.5Ti0.5TaO4 ceramic with a tri-rutile structure was well sintered at 1275 °C with excellent microwave performance: εr ∼33.06, Q × f ∼14,600 GHz, and τf ∼93.95 ppm/°C. Based on the P–V–L theory, the dielectric constant was mainly affected by the formation of Ta–O bonds (∼62%) due to the larger ionic polarization and bond susceptibility. The experimental dielectric constant (33.06) was comparable to the theoretical calculation (P–V–L: 35.11). The lattice energy was also dominated by the Ta–O bond (∼71%) and the intrinsic loss properties. The τf was also affected by the [M1/M2O6] octahedral distortion. In addition, the relative density, grain size, and packing fraction also played a certain role in the microwave dielectric properties. Insights from the Raman spectroscopy revealed that the A1g mode dominated the Raman vibration at 699.44 cm–1. These results were helpful to provide ideas for novel medium dielectric constant materials and contributed to the miniaturization of microwave electronic devices.