Effect of zinc ions non-stoichiometry on the microstructure and microwave dielectric properties of Li2ZnTi3O8 ceramics

Influences of substituting of (Ni1/3Nb2/3)4+for Ti4+on the phase compositions, microstructures, and dielectric properties of Li2Zn[Ti1−x(Ni1/3Nb2/3)x]3O8(0 ≤x≤ 0.3) microwave ceramics

“…Among these systems, cubic-spinel-structured Li2ZnTi3O8 ceramics have attracted much interest due to their simple preparation process, promising dielectric properties (εr = 25.6, Q×f = 72000 GHz, and τf = −11.2 ppm/°C), and low materials cost [14]. Consequently, many researchers have made great efforts to improve microwave dielectric properties by various methods including single-oxide doping, changing sintering technique, heat treatment, and nonstoichiometric strategy [15][16][17][18][19][20][21][22][23][24]. The single-oxide doping was once considered as an effective measure to improve the Q×f value with the substitutions of Mg 2+ , Co 2+ , Cu 2+ , and Ca 2+ by Asite Zn 2+ , and Sn 4+ and Al 3+ for B-site Ti 4+ [15][16][17][18][19].…”

“…Microwave dielectric properties of sintered disks were measured using a network analyzer (N5230C, Agilent, America). The εr value was obtained by the TE011 resonant mode using the Hakki-Coleman method utilizing the Quickwave electromagnetic design (QWED) software [22]. The measured specimens were placed between two well-polished conducting plates that are coated with silver.…”

“…In fact, some degrees of octahedral disorder usually exist in the Li2ZnTi3O8 ceramics. The cation distribution in the spinel crystal structure with the AB2O4 general formula is mainly affected by several factors such as temperature, pressure, and cation substitutions [22,23,48]. Moreover, cation ordering is an important factor affecting the quality factor of microwave ceramics, which 18 / 41 will be discussed in the subsequent section.…”

“…Generally, αL is regarded as a constant (about 10 ppm/°C) whereas τε is a relatively variable parameter, which can be described by the following Eqs. (18)(19)(20)(21)(22):…”

“…𝜀𝜀 𝑟𝑟 = 𝜀𝜀 × 𝜀𝜀 0 (22) where αm, V, εr, ε, and ε0 represent dielectric polarizability, cell volume, relative dielectric constant, dielectric constant, and vacuum dielectric constant, respectively. increased by 323% and 46.8%, respectively.…”