Effects of Zinc Substitution on Crystal Structure and Microwave Dielectric Properties of CaLa₄Ti₅O₁₇ Ceramics

Abstract

Zinc‐substituted CaLa4Ti5O17 microwave dielectric ceramics with the composition of Ca1−xZnxLa4Ti5O17 (x=0–1) were prepared by a solid‐state reaction method. The effects of zinc substitution on sintering behavior, crystal structure, and microwave dielectric properties of CaLa4Ti5O17 ceramics were investigated. Zinc substitution can effectively lower the sintering temperature of CaLa4Ti5O17 ceramics from 1500° to 1100°C. X‐ray diffraction and Raman spectra analysis reveal that with increasing zinc content, the n value of the AnBnO3n+2 structures changed and distinct compounds formed. With increasing Zn2+ content, the perovskite‐slabs decreased from 5‐[BO6] to 4.5‐[BO6] in the range of 0.13≤x≤0.2, and then collapsed to 4‐[BO6] at about x=0.6, with Zn2TiO4 as the secondary phase. The microwave dielectric properties of the sintered ceramics vary with the Zn2+ content. The present ceramics with a small amount of zinc substitution show a relatively small temperature coefficient of resonant frequency of 4.9–8.7 ppm/°C, ɛr of 57–58, and a Q×f value of 11 300–17 400 GHz. When x=0.01, the best combination of dielectric properties, a near‐zero temperature coefficient of resonant frequency of τf∼4.9 ppm/°C, ɛr∼57.6, and Q×f∼17 100 GHz, is obtained.

Dielectric Properties of La(Mg0.5Sn0.5)O3Ceramics Doped with V2O5at Microwave Frequencies

“…In the last decades, there are many microwave dielectric materials have been investigated, such as Ba(Mg 1/3 Ta 2/3 )O 3 , MgTiO 3 , Mg 0.95 Co 0.05 TiO 3 , and CaLa 4 Ti 5 O 17 [3][4][5][6]. Some of the materials have successfully been used in the design of coplanar patch antenna or dielectric resonator antenna.…”

High‐Dielectric‐Constant and Low‐Loss Microwave Dielectric in the (1−x)Nd(Zn1/2Ti1/2)O3–xSrTiO3 System with a Zero Temperature Coefficient of Resonant Frequency

“…However, it contains lead, which will limit its applications in practical cases. Recently, research for new lead‐free materials with such an optimum combination has been ongoing, for instance, (1− x )CaTiO 3 – x Ca(Zn 1/3 Nb 2/3 )O 3 (ɛ r ∼51, Q × f ∼10 860 GHz, and τ f ∼−6 ppm/°C) by Liu et al ., 5 12R–Ba 3 LaNb 3 O 12 (ɛ r ∼44, Q × f ∼9000 GHz) by Rawal et al ., 6 (1− x )ZrTi 2 O 6 – x ZnNb 2 O 6 (ɛ r ∼47, Q × f ∼34 000 GHz, and τ f ∼0 ppm/°C) by RiaziKhoei et al ., 7 Ca[Ti 0.4 (Mg 1/3 Ta 2/3 ) 0.6 ]O 3 (ɛ r ∼60.2, Q × f ∼36 900 GHz, and τ f ∼−10.1 ppm/°C) by Liu et al ., 8 CaLa 4 Ti 5 O 17 (ɛ r ∼57.6, Q × f ∼17 100 GHz, and τ f ∼4.9 ppm/°C) by Zhao et al ., 9 Ba 5 SrNb 4 TiO 18 (ɛ r ∼50.8, Q × f ∼7000 GHz, and τ f ∼83 ppm/°C) by Santha and Sebastian, 10 and Ba 2 La 3 Ti 3 TaO 15 (ɛ r ∼45, Q × f ∼26 828 GHz, and τ f ∼−0.97 ppm/°C) by Fang et al 11 . These results certainly take the advantage of lead‐free materials and can be put to practical applications in 3G components and GPS antennas.…”

Dielectric and complex impedance analysis of Sr5Nb4TiO17 ceramic with perovskite-like structure

“…La 2 Ti 2 O 7 , T c * 1482°C; Sr 2 Nb 2 O 7 , T c * 1327°C) [4,5]. On the other hand, 5-layer members have potential applications as microwave dielectrics due to their low dielectric loss and thermal stability of dielectric properties [8][9][10][11].…”