Tailoring interfacial polarization and surface oxygen chemistry in YO-modified α-FeO nanocomposites for enhanced dielectric response and charge transport behavior

Abstract

This study develops a composition-resolved Y2O3-modified alpha-Fe2O3 nanocomposite platform for tuning interfacial polarization, surface oxygen chemistry, and frequency-dependent charge transport in oxide dielectrics. Nanocomposites containing 1, 3, 5, and 10 mol% Y2O3 were synthesized through a sol-gel-assisted chemical precipitation route and characterized by XRD, FT-IR, Raman, XPS, FE-SEM/EDX, and broadband dielectric spectroscopy over the 1 kHz-10 MHz range. XRD analysis confirmed the preservation of the dominant hematite alpha-Fe2O3 framework and quantified the composition-dependent structural response: the lattice parameters changed from a = 5.0116 +/- 0.0056 & Aring; and c = 13.6334 +/- 0.0421 & Aring; for pristine Fe2O3 to a = 5.0211 +/- 0.0036 & Aring; and c = 13.6767 +/- 0.0275 & Aring; for Fe2O3-10Y2O3, while the median Scherrer crystallite size increased from 28.09 to 37.43 nm across the same comparison. FT-IR, Raman, and XPS results collectively revealed systematic modification of Fe-O/Y-O bonding environments, surface hydroxylation, and chemically distinct oxygen-related interfacial sites, while FE-SEM/EDX verified progressive Y distribution with the Y content increasing from 2.4 +/- 0.1 wt% to 10.9 +/- 0.1 wt% in the modified series. At 1 kHz, the dielectric constant increased from 10.133 +/- 0.015 for pristine Fe2O3 to 14.743 +/- 0.005 for Fe2O3-10Y2O3, corresponding to a 45.5% enhancement; dielectric loss increased from 0.650 +/- 0.006 to 0.959 +/- 0.010, whereas tan delta remained narrowly distributed between 0.064 and 0.065. The AC conductivity increased from (3.618 +/- 0.034) & times; 10(-)8 to (5.336 +/- 0.057) & times; 10(-)8 S/cm, supporting composition-tunable localized transport while retaining a low-conductivity dielectric regime. The combined structural, chemical, morphological, and dielectric evidence demonstrates that Y2O3 modification reinforces alpha-Fe2O3 through interface-assisted polarization and controlled relaxation dynamics, making these nanocomposites suitable for moderate-permittivity dielectric layers, capacitive oxide components, and frequency-dependent electronic applications.