Original Research
Enhanced dielectric performance of Dy - substituted YMn2O5 for high-frequency applications

https://doi.org/10.1016/j.pnsc.2021.07.007Get rights and content
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Highlights

  • Impedance spectroscopy and electrical modulus study confirms the presence of the non-Debye type of dielectric relaxation.

  • The reduced hopping rate with Dy3+ substitution for Y3+ ions at A sites for YMn2O5 is in charge of the decrease in dielectric constant and dielectric loss.

  • Activation energies calculated from the impedance and Modulus proves to be close, which suggests that the relaxation process refers to electron hopping.

  • For each compound, we observe two relaxations one at low temperature related to the charge carriers hopping between Mn3+ and Mn4+ and the other at high temperature is associated with oxygen vacancies.

Abstract

The dielectric performances as well as the effects of Dy3+ ions content at A sites of YMn2O5 (YMO) [x ​= ​0 (YDM0) and x ​= ​0.4 (YDM0.4)] polycrystalline samples were explored. These compounds were synthesized via sol–gel method. X-Ray diffraction and Raman measurements proved the high quality of the compounds that crystallized in an orthorhombic structure with the Pbam space group. Besides, impedance spectroscopy and electrical modulus studies revealed that both samples exhibited a non-Debye's type of relaxation. The decrease of impedance for YDM0.4 compared to the pure YDM0, may be attributed to the decrease in charge transfer resistance. Concerning the fit of impedance spectra, they confirmed that both compounds were simultaneously capacitive and resistive. Furthermore, the activation energies obtained from Modulus and complex impedance were proven to be neighboring, suggesting that the relaxation process refers to electron hopping. For each compound, the evolution of ε' and tan ​δ with temperature indicated a clearer relaxor behavior, namely the existence of two relaxations. The first one detected at low temperature is related to the charge carriers hopping between Mn3+ and Mn4+ and the second at high temperature is associated with oxygen vacancies. The reduced hopping rate with Dy3+ substitution for Y3+ ions at A sites is responsible for the decrease in dielectric constant and dielectric loss. These significant findings demonstrate that these materials can be invested in a fruitful use in UV photo-detector and power applications in high frequency as microwave, millimeter wave signal processing, for civilian, military and space applications.

Keywords

Multiferroic
Relaxation phenomenon
High dielectric constant
Relaxor behavior

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