A systematic study of the effect of magnetic dilution of CuO by diamagnetic CaO and SrO using electron paramagnetic resonance and X-ray diffraction studies was carried out. Three different combinations of CuO with CaO/SrO were prepared and calcined at different temperatures from room temperature (RT) to 800ºC. In both the CaO-CuO and SrO-CuO systems, the first appearance of the signal occurred at much lower calcination temperatures compared to that of CuO. On increasing the concentration of the diamagnetic additives, the emergence of the signals became earlier. XRD study showed that below 800ºC, no chemical reaction takes place, indicating that the EPR spectral variations are governed only by the dilution effect of the diamagnetic CaO/SrO molecules. The magnetically coupled Cu-O-Cu chains in CuO are interspersed with the diamagnetic molecules and thus effectively enhance the reduction of the spin correlation length. The spectrum that emerged as a result of this consists of a broad low field signal and a sharp signal at g≃2. The broad signal is attributed to the remnants of short range order and the sharp g≃2 signal to the Cu 2+ monomers formed. At higher temperatures, the high field shift and weakening of the low field signal indicate the destruction of magnetic coupling in CuO.
Corrigendum to ‘Magnetic dilution effect of nano-crystalline NiFe2O4 synthesized via sucrose-assisted combustion route’[Ceram. Int. 40/1PA (2014) 675–681][1]
