Modification in the structural and dielectric properties of ErCrO3 on Fe substitution

Abstract

Polycrystalline samples of ErCr_1-xFe_xO₃ (0≤ x ≤ 0.30) have been synthesized in single-phase form using the sol-gel technique. XRD patterns analyzed via Rietveld refinement confirm the orthorhombic structure with unit cell volumes increasing from 216.989 Å³ (x = 0.00) to 218.565 Å³ (x = 0.30), attributed to the substitution of larger Fe³⁺ ions (0.645 Å) for Cr³⁺ ions (0.615 Å). Scanning Electron Microscopy (SEM) showed grain sizes ranging from 335 nm (x = 0.00) to 689 nm (x = 0.15). Energy Dispersive X-ray Spectroscopy (EDX) and Raman Spectroscopy corroborated the formation of the orthochromite structure. Impedance spectroscopy study revealed a discontinuity in the resistive behavior for all the samples showing the appearance of positive temperature coefficient of resistance (positive TCR) like transition in the temperature range of 393 K–443 K. Similar trend was also observed in the dielectric and the conductivity measurements around the same temperature range. All the ErCr_1-xFe_xO₃ compounds showed a colossal dielectric constant value (>10⁴) at room temperature, supporting the potential use of these compounds in electronic devices. The ac conductivity spectra followed Jonscher Power Law (JPL).