부산대학교 도서관

In this report, a detailed investigation of magnetocaloric properties of Ce3+Zn0.6Co0.4CexFe2-xO4(x=0.02,0.04,0.06)3¯TCTBxCe3+Ce3+-doped zinc–cobalt spinel ferrite nanoparticles with the generic formula Ce3+Zn0.6Co0.4CexFe2-xO4(x=0.02,0.04,0.06)3¯TCTBxCe3+Ce3+ synthesized via chemical coprecipitation method had been carried out. Rietveld analysis of the X-ray diffraction (XRD) patterns confirmed the phase purity of the nanoparticles and the corresponding space group was found to be FdCe3+Zn0.6Co0.4CexFe2-xO4(x=0.02,0.04,0.06)3¯TCTBxCe3+Ce3+m for the series. The shift of microstrain inside the crystal from compressive to tensile regime with doping of Ce confirms the expansion of unit cell in the whole series. Raman spectroscopy also confirmed the spinel structure of the samples. Coexistence of magnetic phases below room temperature is observed from the magnetization measurements with temperature under 500 Oe applied field. A decrease in Ce3+Zn0.6Co0.4CexFe2-xO4(x=0.02,0.04,0.06)3¯TCTBxCe3+Ce3+ as well as Ce3+Zn0.6Co0.4CexFe2-xO4(x=0.02,0.04,0.06)3¯TCTBxCe3+Ce3+ was observed with increase in Ce3+Zn0.6Co0.4CexFe2-xO4(x=0.02,0.04,0.06)3¯TCTBxCe3+Ce3+ due to weakening of exchange interaction. The transition temperature of Ce-04 nanoparticles is quite close to room temperature which may be beneficial for room temperature magnetic refrigeration. Though the Ce3+Zn0.6Co0.4CexFe2-xO4(x=0.02,0.04,0.06)3¯TCTBxCe3+Ce3+ doping in the series did not favour enhancement of magnetic entropy change, it enhanced the RCP which could be beneficial for room temperature or below room temperature magnetic refrigeration. A good correlation was established between magnetocaloric properties and critical behaviour of Ce3+Zn0.6Co0.4CexFe2-xO4(x=0.02,0.04,0.06)3¯TCTBxCe3+Ce3+-doped zinc–cobalt spinel ferrite nanoparticles.