Usage of P–V–L bond theory in studying the structural/property regulation of microwave dielectric ceramics: a review

Abstract

Structure/properties regulation is widely investigated for providing theoretical foundations and guidances for designing microwave dielectric ceramics. The P-V-L bond theory targets in providing detailed structural parameters of crystals and fundamental...

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

“…In other words, the U in the crystal structure represented the binding capacity of anion, whereas the greater the binding capacity, the more stable the structure, and the lower the corresponding intrinsic loss. Therefore, the calculation formula of U in μ chemical bonds was the following: where Z + μ and Z – μ are the chemical valences of cations and anions. Besides, f c μ and f i μ stand for the ionic and covalent properties of the bonds.…”

Crystal structure and enhanced microwave dielectric properties of the Ce2[Zr1−x(Al1/2Ta1/2)x]3(MoO4)9 ceramics at microwave frequency

“…In recent years, Mo-based microwave dielectric ceramics were studied in depth, as shown in Fig. 8 [10,[17][18][19][20][21][26][27][28][29][30][31][32] In general, the microwave dielectric properties are associated with the extrinsic factors. The extrinsic factors include grain boundaries, pores, abnormal grains, defect, and dislocation, which are the main factors that produce the dielectric loss.…”

“…Densification and a relatively uniform microstructure are the main reasons for optimizing the quality factor; the decline of Q × f values at a higher sintering temperature can be attributed to intrinsic loss[24,25].In recent years, Mo-based microwave dielectric ceramics were studied in depth, as shown in Fig. 8[10,[17][18][19][20][21][26][27][28][29][30][31][32]. Most Mo-based microwave dielectric ceramics have Q × f in the range of 20,000-80,000 GHz.…”

Design of a High-Efficiency and -Gain Antenna Using Novel Low-Loss, Temperature-Stable Li2Ti1–x(Cu1/3Nb2/3)xO3 Microwave Dielectric Ceramics

“…Therefore, the covalency will increase after the (Cu 1/3 Nb 2/3 ) 4+ substitution for Ti 4+ . Several previous studies have revealed that the increased covalency of the M– O bond in the [ M O 6 ] octahedron by the ion substitution would lower the ε r of ceramics, − for example, the Ta substitution for Nb in the [NbO 6 ] octahedron of Mg 4 (Nb 2– x Ta x )­O 9 ceramics, the Sb substitution for Nb in the [NbO 6 ] octahedron of Mg 4 (Nb 2– x Sb x )­O 9 ceramics, and the (Zn 1/3 Nb 2/3 ) 4+ substitution for Ti in the [TiO 6 ] octahedron of Ba 3 Ti 4– x (Zn 1/3 Nb 2/3 ) x Nb 4 O 21 ceramics . Hence, the dielectric constant of LTCN x (0 ≤ x ≤ 0.4) ceramics decreased with an increase in x , which might be mainly ascribed to the fact that the covalency of the Ti–O bond is weaker than that of Cu–O and Nb–O bonds in an oxygen octahedron.…”