Sub-lattice polarization states in anti-ferroelectrics and their relaxation process

Vopson, Melvin; Tan, Xiaoli; Namvar, Esmaeil; Belusky, Michal; Thompson, Stephen P.; Kuncser, V.; Plazaola, F.; Unzueta, I.; Tang, Chiu C.

doi:10.1016/j.cap.2019.03.009

Cited by 9 publications

(1 citation statement)

References 25 publications

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“…At a very low temperature, the real part of the complex dielectric constant and the loss tangent of 2-thiophene carboxaldehyde and 2-thiophenecarboxylic acid are very small. At low temperature conditions, the relaxation time (τ) is very long; thus, ωτ ≫ 1 and ω 2 τ 2 ≫ 1. , The real part of the complex dielectric constant (ε′) examines the capacity of the material to store the electrical energy . According to the Debye equation [eq ] with a long relaxation time, the real part of the complex dielectric constant (ε′) is inversely proportional to ω 2 τ 2 , i.e., ε′ ∝ 1/ω 2 τ 2 , and the loss tangent (tan δ) is inversely proportional to ωτ, i.e., tan δ ∝ 1/ωτ; therefore, the real part of the complex dielectric constant and the loss tangent of 2-thiophene carboxaldehyde and 2-thiophenecarboxylic acid are relatively small.…”

Section: Resultsmentioning

confidence: 99%

The Dielectric Properties of Thiophene Model Compounds: Insights for Microwave Desulfurization of Coking Coal

2020

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Microwave desulfurization capitalizes on the different dielectric properties of sulfur-containing and sulfur-free components in coal. However, the dielectric properties of thiophene compounds, the predominant sulfur species in coking coal, are not well understood. Herein, the dielectric properties of different thiophene model compounds containing coal-like compositions and structures are investigated under the impact of microwave frequency and temperature. The increases of aromaticity in thiophene compounds suppress their microwave responses to the electric irradiation, as indicated by the decrease of the loss tangent values, while thiophene compounds with polar functional groups exhibit higher microwave reactivity. Additionally, the oxidation of the functional groups in thiophene further increases the ability to absorb and convert the microwave energy to the thermal energy. The dielectric properties of thiophene compounds are also sensitive to the changes in microwave frequency and temperatures. The thiophene compounds exhibit a higher microwave adsorption capacity at the microwave frequency of 915 MHz relative to 2450 MHz, which is opposite to the trends for the penetration depths. Such an observation indicates that the desulfurization of thiophene compounds is more readily achieved at the frequency of 915 MHz. The findings associated with the dielectric properties of different thiophene compounds mark an important step toward optimizing the microwave desulfurization of coal.

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Section: Resultsmentioning

confidence: 99%