Publication: AC Conductivity and dielectric properties of lepidocrocite-type alkali titanate tunable by interlayer cation and intralayer metal
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Issued Date
2020
Resource Type
File Type
application/pdf
ISSN
201669
Other identifier(s)
2-s2.0-85094983748
Rights
Srinakharinwirot University
Rights Holder(s)
Scopus
Bibliographic Citation
Inorganic Chemistry. Vol 59, No.21 (2020), p.15813-15823
Suggested Citation
Charoonsuk T., Sriphan S., Pulphol P., Vittayakorn W., Vittayakorn N., Maluangnont T. AC Conductivity and dielectric properties of lepidocrocite-type alkali titanate tunable by interlayer cation and intralayer metal. Inorganic Chemistry. Vol 59, No.21 (2020), p.15813-15823. doi:10.1021/acs.inorgchem.0c02264 Retrieved from: https://hdl.handle.net/20.500.14740/5778
Abstract
The lepidocrocite-type layered alkali titanate AxMyTi2-yO4 has diverse chemical compositions with variation in charge per formula unit x, the interlayer cation A+, and the intralayer metal M. Despite this multivariable nature, the composition dependence of physical properties is not well explored. We report herein the AC conductivity and the complementary dielectric properties of Cs0.7M0.35Ti1.65O4, K0.8M0.4Ti1.6O4 (M = Zn, Ni), and the mixed-interlayer ion Cs0.6K0.1Zn0.35Ti1.65O4. For Cs0.7Zn0.35Ti1.65O4, the total AC conductivity is ~7 × 10-8 to 2 × 10-6 S·cm-1 at 200-350 °C, associating with an activation energy Ea ∼865 meV. Meanwhile, the conductivity of K0.8Zn0.4Ti1.6O4 is higher by 1 order of magnitude at much lower temperature (25-150 °C) and a smaller Ea ∼250 meV. This difference originates from the compositional robustness of the cesium-containing samples, contrasting with the sintering-induced changes in the potassium analogues. For the latter, the loss of the interlayer K+ ion results in (i) generation of carriers due to charge compensation, (ii) reduction of sheet charge density and weakening of electrostatic attraction, and (iii) widening of the interlayer distance, all contributing to a lower Ea in K0.8M0.4Ti1.6O4. The angular frequency dependence of conductivity, dielectric permittivity (up to a colossal value of 109), and dielectric loss follows the universal power law. Our work demonstrates the potential of simple compositional variation for electrical properties tuning, prompting a more in-depth investigation covering a wider range of possible candidates of x, A+, and M in lepidocrocite titanate. ©