Laser Raman micro spectroscopy and high frequency dielectric properties of silica- xerogel loaded with different concentrations of α-Fe2O3

Abstract

Sol-gel derived nano-composites silica-gel doped with different iron oxide concentrations at (3.5, 11, 33 and 37 mol. %) sintered at constant temperature at 1170°C, are illustrated in this work. Structure, surface morphology, high frequency dielectric and magnetic trends of the mentioned nano-composites analyzed and investigated through XRD, UV-Vis, TEM, FESEM and Magnetic hysteresis curves. Raman micro-spectroscopy gives rise to samples homogenous distribution. XRD illustrate that the Hematite (α-Fe2O3) is the optimum phase rather than the Maghemite (γ-Fe2O3) and Magnetite (Ԑ- Fe2O3). Big amount of Hematite (α-Fe2O3) crystalline nano-particles are expected at 37 mol. % of Fe2¬O3. XRD confirmed that the average crystallite size increased from (25-31) nm with increasing the concentration of (α-Fe2O3) from 3.5 up to 37 mol%. The A.C. conductivity σac increased by increasing the α-Fe2O3 content, according to the presence of oxygen vacancy and the crystalline size increases. The decreasing behavior in magnetization value (Ms) is related to the changes of the crystallite size, magnetic iron oxide particles and concentration. All analysis explains Hematite is extremely stable at ambient conditions and at high temperatures, so it is the better for particular applications.

Keywords

• iron oxide
• sol gel
• laser raman micro spectroscopy
• impedance analyzer (keysight-e4991b).