Impact of Sintering Temperature on the Structural, Optical, and Dielectric Properties of Er<sub>2</sub>O<sub>3</sub>-doped ZrO<sub>2</sub> Ceramics Synthesized via Solid-State Reaction

Er2O3-doped zirconium dioxide ceramic samples were successfully synthesized using the solid-state reaction method at various sintering temperatures. The synthesized samples were analyzed using XRD, FESEM, EDAX, FTIR, and UV-Vis spectroscopy, and their dielectric properties-including dielectric constant (εꞌ), dielectric loss (εꞌꞌ), and AC conductivity (σac)-were measured at ambient temperature. The average particle sizes calculated from the XRD spectra indicated an increase in particle size as the sintering temperature rose. The optical properties analyzed using a UV-Vis spectrophotometer revealed a reduction in band gap energy with increasing sintering temperature, which can be attributed to the growth in particle size. EDS analysis showed no impurities or unexpected elements, confirming the purity and controlled doping of Er2O3 in the ZrO2 samples. The dielectric constant and dielectric loss of Er2O3-doped ZrO2 exhibited a noticeable decrease with increasing frequency (Maxwell-Wagner polarization). Additionally, both εꞌ and εꞌꞌ were greater in the lower frequency range. Major Findings: The study reveals that increasing the sintering temperature enhances crystallite size and improves the structural and optical properties of Er2O3-doped ZrO2 ceramics. The dielectric constant and dielectric loss exhibit frequency-dependent behaviour, with higher values at lower frequencies, attributed to space charge polarization. The reduction in band gap with increasing sintering temperature suggests improved crystallinity and grain growth.