High temperature X-ray diffraction study of Ni–Cu ferrite

The thermal expansion of Ni1−xCuxFe2O4 spinel with cubic structure has been investigated using high temperature X-ray diffraction (HT-XRD) technique and thermogravimetric analysis (TGA). The spinel phase of Ni1−xCuxFe2O4 was maintained for all temperatures in the range (30–600 °C) without any dramatic change in the crystal structure. The lattice parameter for all samples is increased by increasing the temperature in linear relation, signify lattice expanded. Above transition temperature, some peaks disappeared which make up weakness in the lattice structure. The thermal expansion coefficients were 9 × 10−5 °C−1, 2 × 10−5 °C−1 and 7 × 10−5 °C−1 for sample 0.2, 0.5, and 0.8 respectively. The thermogravimetric study (30–600 °C) reveals that all samples increased corresponding to thermal expansion.

► The appearance of most reflections at high temperature indicates no dramatic change in the crystal structure with temperature. ► Above transition temperature some peaks disappeared which make up weakness in the lattice structure. ► The thermal expansion of the Ni1−xCuxFe2O4 compositions is not due to chemical expansion but due to thermal expansion of the lattice variation of the compositions. ► The thermogravimetric shows behaviors different from the literatures. ► The thermal expansion coefficients were different with different compositions.