ZnAl2O4–ZnO heterostructured nanocomposite with giant dielectric permittivity and epsilon-negative response: frequency- and temperature-dependent dielectric behavior
- 1Laboratoire de Recherche Matériaux Avancés et Nanotechnologies (LRMAN), Institut Supérieur des Sciences Appliquées et de Technologie de Kasserine, Université de Kairouan BP 471 1200 Kasserine Tunisia
- 2Department of Physics, University of Kotli Azad Jammu and Kashmir Kotli 11100 Pakistan
Abstract
The development of multifunctional oxide heterostructures exhibiting simultaneously enhanced dielectric, electrical, and electromagnetic properties is highly desirable for next-generation electronic and radio-frequency devices. In this work, a ZnAl2O4@ZnO heterostructured nanocomposite was successfully synthesized via a combination of sol–gel auto-combustion and chemical precipitation techniques. X-ray diffraction combined with Rietveld refinement confirmed the coexistence of highly crystalline cubic ZnAl2O4 (15.1 wt%) and hexagonal ZnO (84.9 wt%) phases without detectable impurities, while elemental, morphological, and internal microstructure analyses verified the successful formation of a homogeneous ZnO phase surrounding the ZnAl2O4 cores. The nanocomposite exhibits a giant low-frequency dielectric permittivity reaching approximately 4 × 104 at elevated temperatures, which is attributed primarily to strong Maxwell–Wagner interfacial polarization associated with the ZnAl2O4/ZnO heterointerfaces. Increasing the excitation frequency suppresses the interfacial polarization and produces a Lorentz-type dielectric resonance centered at approximately 43–44 MHz, accompanied by a transition of the real permittivity from positive to negative values, reaching approximately −64, together with an ε′ = 0 crossover. The temperature-dependent dielectric response also exhibits a relatively stable permittivity variation within approximately ±10% over the −55 to +125 °C range at 10 MHz, corresponding to X7P-like temperature stability based on conventional EIA temperature-stability criteria. These results demonstrate that the ZnAl2O4@ZnO heterostructured nanocomposite architecture provides strongly tunable dielectric behavior, spanning giant positive permittivity at low frequencies and elevated temperatures to negative-permittivity response in the MHz regime. While these dielectric characteristics may be of interest for future investigations of temperature-stable capacitive components and electromagnetic structures, device-level performance, including RF resonators, electromagnetic shielding, metamaterials, and ENZ devices, was not directly evaluated in the present work.
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BibTeX
@article{moualhi2026znal2o4zno,
title = {{ZnAl2O4–ZnO heterostructured nanocomposite with giant dielectric permittivity and epsilon-negative response: frequency- and temperature-dependent dielectric behavior}},
author = {Youssef Moualhi and Muhammad Javed and Hedi Rahmouni},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra07001a},
url = {https://europepmc.org/article/PMC/PMC13670036},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - ZnAl2O4–ZnO heterostructured nanocomposite with giant dielectric permittivity and epsilon-negative response: frequency- and temperature-dependent dielectric behavior
AU - Youssef Moualhi
AU - Muhammad Javed
AU - Hedi Rahmouni
PY - 2026
DA - 2026/10/15
JO - RSC advances
DO - 10.1039/d6ra07001a
UR - https://europepmc.org/article/PMC/PMC13670036
AB - The development of multifunctional oxide heterostructures exhibiting simultaneously enhanced dielectric, electrical, and electromagnetic properties is highly desirable for next-generation electronic and radio-frequency devices. In this work, a ZnAl2O4@ZnO heterostructured nanocomposite was successfully synthesized via a combination of sol–gel auto-combustion and chemical precipitation techniques. X-ray diffraction combined with Rietveld refinement confirmed the coexistence of highly crystalline cubic ZnAl2O4 (15.1 wt%) and hexagonal ZnO (84.9 wt%) phases without detectable impurities, while elemental, morphological, and internal microstructure analyses verified the successful formation of a homogeneous ZnO phase surrounding the ZnAl2O4 cores. The nanocomposite exhibits a giant low-frequency dielectric permittivity reaching approximately 4 × 104 at elevated temperatures, which is attributed primarily to strong Maxwell–Wagner interfacial polarization associated with the ZnAl2O4/ZnO heterointerfaces. Increasing the excitation frequency suppresses the interfacial polarization and produces a Lorentz-type dielectric resonance centered at approximately 43–44 MHz, accompanied by a transition of the real permittivity from positive to negative values, reaching approximately −64, together with an ε′ = 0 crossover. The temperature-dependent dielectric response also exhibits a relatively stable permittivity variation within approximately ±10% over the −55 to +125 °C range at 10 MHz, corresponding to X7P-like temperature stability based on conventional EIA temperature-stability criteria. These results demonstrate that the ZnAl2O4@ZnO heterostructured nanocomposite architecture provides strongly tunable dielectric behavior, spanning giant positive permittivity at low frequencies and elevated temperatures to negative-permittivity response in the MHz regime. While these dielectric characteristics may be of interest for future investigations of temperature-stable capacitive components and electromagnetic structures, device-level performance, including RF resonators, electromagnetic shielding, metamaterials, and ENZ devices, was not directly evaluated in the present work.
SN - 2046-2069
ER -