Phase structure, bond traits, and intrinsic dielectric response of NiTa₂O₆-TiO₂ microwave dielectric ceramics investigated by bond theory and vibrational spectroscopy

The present work reports the synthesis and structure-property of a tri-rutile Ni0.5Ti0.5TaO4 microwave dielectric ceramic. It is found that the Ni0.5Ti0.5TaO4 ceramic belongs to the solid solution of tetragonal tri-rutile NiTa2O6. Based on Raman spectroscopy and group theory prediction, the A(1g) Raman-active mode in 702.4 cm(-1), belonging to the synergistic vibration of Ti/Ta2 cations and O anion, dominates the Raman-active vibrations. The intrinsic factor to the microwave dielectric traits is studied using the dielectric theory of crystal structure and infrared reflective spectroscopy from the aspect of the crystal structure. The dielectric loss of Ni0.5Ti0.5TaO4 ceramic at the microwave range originates from the absorption of structural phonon oscillation, discovering the micro-polarization mechanism. Also, the contributions of chemical bonds, especially the importance of Ti/Ta2 cation to the chemical bond susceptibility and structural lattice stability, are reflected. Accordingly, the Ti site was partially replaced by the (Al0.5Nb0.5)(4+) complex cation, which improved the microwave dielectric performances with an increase of Q x f value similar to 39%.