Combustion synthesis of nanocrystalline porous CoFexAl2-xO4 spinels: Structural, textural, magnetic, and electrical properties

Abstract

A simple ammonia fueled combustion route was used to synthesize a series of nanocrystalline porous CoFexAl2-xO4 spinel samples with different Fe concentration (0.00 ≤ x ≤ 2.00) at 400 °C. The structural, morphological, and textural properties of the synthesized powders were analyzed by using XRD, FT-IR, FESEM, TEM, SAED, and N2-physisorption techniques. The electrical and magnetic properties of the spinels were also studied using electrical conductivity and vibrating sample magnetometer (VSM) techniques. The XRD and SAED analyses results revealed that the synthesized samples possessed partially inverse cubic spinel structure with Fe3+ and Al3+ cations distribution. The crystallite size was observed in the range of 14–45 nm, whereas the diameter of the particles obtained from FESEM analysis is in the range of 143–284 nm. The CoAl2O4 sample exhibited low saturation magnetization (Ms) and coercivity (Hc) values, however the magnetic parameter and conductivity values increased monotonically with incorporation of Fe3+ ions. In addition, N2 adsorption isotherm change, Type IV to Type II was observed with increase of Fe concentration in the spinel structure. The achieved results indicate that the ammonia fueled combustion method could be a promising method to produce nanosized porous ferrite spinels.