Investigation of magnetic phase transitions in Ni0.5Cu0.25Zn0.25Fe2-xLaxO4 nanoferrites using magnetic and in-situ ultrasonic measurements

Abstract

In this study, Ni0.5Cu0.25Zn0.25Fe2-xLaxO4 (x = 0.000, 0.025, 0.050, 0.075 and 0.100) spinel ferrites were prepared using sonochemical reactor. X-ray diffraction spectra were used to authorize/confirm the cubic spinel ferrite single-phase crystalline nature of the sample. The morphology of the prepared Ni0.5Cu0.25Zn0.25Fe2-xLaxO4 spinel ferrites was investigated by scanning electron microscope. It is observed that all the particles have devised spherical-like morphology. The ultrasonic non-destructive technique is also a versatile/flexible method/tool to explore/measure the Curie temperature (TC) in the spinel ferrites. In-situ ultrasonic velocity measurements in the range of temperature from 300 to 900 K were carried out. The detected anomalous characteristic/behavior in the ultrasonic velocity was used to explore the TC of the prepared sample. TC of Ni0.5Cu0.25Zn0.25Fe2-xLaxO4 is 735, 705,690, 675 and 655 K for the different composition x = 0.000, 0.025, 0.050, 0.075 and 0.100 respectively. The value of TC decreases with increasing La3+ doping concentration. Because La3+ ions are strongly paramagnetic, their presence reduces TC, which increases the paramagnetic zone. The vibrating sample magnetometry and susceptibility measurements have been used to investigate the influence of La3+ substitution on magnetic characteristics for further validation.