Dielectric Loss Spectrum of Ceramic MgTiO₃ Investigated by AC Impedance and Microwave Resonator Measurements

Abstract

MgTiO3 ceramic was selected as a model material of the microwave dielectric ceramics for the investigation of the dielectric loss spectrum. Conductivity spectra in the low‐frequency range 1–106 Hz at elevated temperatures and the dielectric loss spectrum in the microwave range 6–14 GHz at room temperature were characterized by AC impedance spectroscopy and the microwave resonator method, respectively. The experimental data were analyzed by using Jonscher's universal power law, the Arrhenius equation as well as the classic dispersion theory. Consequently, a dielectric loss spectrum (tg δ∼f plot) at room temperature in a wide frequency range was obtained. Based on the loss spectrum, the dielectric loss can be classified into three mechanisms in MgTiO3 ceramic (each dominates the loss in different frequency ranges): DC conductance (in DC field), AC conductance (<107 Hz), and anharmonicity of lattice vibration (in GHz range). The influence of defects on the microwave dielectric loss possibly is because of atom defects via damage of the perfection of lattice and modification of the anharmonic force in lattice, while the electronic defects trapped on the atomic defects affect the DC and AC losses.

Low temperature synthesis and characterization of nano‐crystalline Mg(Zr0.05Ti0.95)O3 ceramics

“…It is seen from the figure that the tand is maximum at lower frequencies and is found to decrease with frequency at all the measured temperatures. Similar behavior was observed by Kuang 35 for MgTiO 3 sample in this frequency range. This tand depends on many factors: anharmonic lattice vibration, DC/AC conductivity of charge carrier etc.…”

“…At microwave frequencies, the loss is possibly due to atom defect or impurity atom. 35 In terms of temperature, when the temperature increases the conduction loss enhances due to the increase in conductivity which reinforces the value of dielectric loss with increasing temperature. 36,37 The value of tand is in the range of 10 À4 at 20 MHz for MZrT sample, sintered at 950°C for 3 hours.…”

“…This tanδ depends on many factors: anharmonic lattice vibration, DC/AC conductivity of charge carrier etc. At microwave frequencies, the loss is possibly due to atom defect or impurity atom . In terms of temperature, when the temperature increases the conduction loss enhances due to the increase in conductivity which reinforces the value of dielectric loss with increasing temperature .…”

Microwave dielectric properties of ATiO3 (A = Ni, Mg, Co, Mn) ceramics

“…3 With the types of Asite ions of ATiO 3 ceramics, the microwave dielectric properties are expected to be changed. Dependence of microwave dielectric properties on structural characteristics should be studied to control and predict the dielectric properties of ATiO 3 ilmenite compounds.…”

Low‐Loss Microwave Dielectric Material Based on Magnesium Titanate

“…Compounds in the MgO–TiO 2 system with dielectric constants of 10–20, and a high Q have attracted the most attention. For example, ilmenite MgTiO 3 reportedly has dielectric properties ɛ=16, Q × f =100 000–200 000 GHz, and τ f ∼−40 ppm/°C 5–8 . The substituting of a few Mg 2+ ions by Nb 5+ , Ni 2+ , Co 2+ , Zn 2+ , and Ta 5+ has been reported to modify efficiently the dielectric properties of MgTiO 3 and Mg 2 TiO 4 3–7 .…”