Investigation of phase composition and microwave dielectric properties of MgO‐Ta₂O₅ ceramics with ultrahigh Qf value

Abstract

Four MgO‐Ta2O5 ceramics with the MgO/Ta2O5 mole ratio x = 1, 2, 3, and 4 were prepared by traditional solid‐state reaction method, and the influence of x on the phase composition, microstructure, and dielectric properties (the dielectric constant εr, the temperature coefficient of resonant frequency τf and the quality factor Qf) of the materials was investigated using XRD, SEM, etc. The results indicated that the ceramics were composed of two crystalline phases MgTa2O6 and Mg4Ta2O9 in the composition range studied, and that the dielectric properties ln ε, 1/Qf, and τf changed proportionally to the fraction of main crystal phases, which meet perfectly with the mixing model proposed in this study. It is obvious that the proportion of the two crystal phases could be precisely controlled by x, and thereby, the dielectric properties can be conveniently and precisely tailored. Our research provided a new microwave dielectric ceramic with the composition of 2MgO‐Ta2O5, which has an ultrahigh Qf value (211 000 GHz), low dielectric constant εr (19.9), and near zero temperature coefficient of resonant frequency τf (8 ppm/°C).

Synthesis and thermophysical properties of ATa2O6 (A = Co, Ni, Mg, Ca) tantalates with robust CMAS resistance

“…Therefore, A Ta 2 O 6 ( A = Co, Ni, Mg, Ca) ceramics are studied in this work. In recent years, some scholars focused on the properties of AB 2 O 6 ‐type ceramics ( A 2+ and B 5+ ) 36–41 . Zhang et al.…”

“…studied the structures and dielectric performance of Mg 1‐x Zn x Ta 2 O 6 solid solutions 38 ; Dang et al. documented the phases and properties of MgTa 2 O 6 and Mg 4 Ta 2 O 9 ceramics 39 ; and Kim et al. documented the influence of fabrication conditions on the properties of MgTa 2 O 6 and MgNb 2 O 6 ceramics 40 .…”

“…In recent years, some scholars focused on the properties of AB 2 O 6 -type ceramics (A 2+ and B 5+ ). [36][37][38][39][40][41] 40 There is no system investigation on the high-temperature properties of ATa 2 O 6 ceramics for E/TBC applications. To study the potential of ATa 2 O 6 as E/TBCs, we first investigated its thermophysical properties.…”

Effect of Ce3+doping on phase and microwave dielectric properties of 0.94MgTiO3−0.06(Ca0.8Sr0.2)TiO3ceramics

“…High‐quality microwave dielectric materials need to have an appropriate dielectric constant ( ε r ), a high quality factor ( Q×f , Q = 1/tanδ) for better frequency selectivity, and a near‐zero temperature coefficient ( τ f ) of resonant frequency for good temperature stability 4–6 . Especially, K20 microwave dielectric ceramics have been widely studied because the low dielectric constant ( ε r ∼ 20) facilitates a smaller signal transmission delay, such as MgTiO 3 ‐based (0.95MgTiO 3 ‐0.05CaTiO 3 : ε r ∼ 20–21, Q × f ∼ 56 000 GHz, τ f ∼ 0 ppm/°C), 7 Li 2 TiO 3 ‐system (Li 2 Ti 0.75 (Mg 1/3 Nb 2/3 ) 0.25 O 3 : ε r ∼ 19.9, Q × f ∼ 60 950 GHz, τ f ∼ −6.1 ppm/°C, Li 2 Ti 1‐x (Cu 1/3 Nb 2/3 ) x O 3 : ε r ∼ 21.0, Q × f ∼ 51 940 GHz, τ f ∼ 1.4 ppm/°C), 8,9 CaSmAlO 4 ‐based ((Ca 1.15 Sm 0.85 )(Ti 0.15 Al 0.85 )O 4 : ε r ∼ 20.2, Q × f ∼ 97 800 GHz, τ f ∼ −0.5 ppm/°C), 10 and commercial materials with superior Q × f values (Ba(Mg 1/3 Ta 2/3 )O 3 : ε r ∼ 24.662, Q × f ∼ 248 414 GHz, τ f ∼ −0.55 ppm/°C, 11 MgTa 2 O 6 : ε r ∼ 19.9, Q × f ∼ 211 000 GHz, τ f ∼ 8 ppm/°C 12 ). Among them, MgTiO 3 (MT) with prominent dielectric properties ( ε r ∼ 17, Q×f ∼ 160,000 GHz and τ f ∼ −51 ppm/°C), abundant raw materials, and low prices, is one of the important candidates for 5G microwave applications 13,14 .…”