XRD, HRTEM and magnetic properties of mixed spinel nanocrystalline Ni–Zn–Cu-ferrite

• Published in: Journal of alloys and compounds Vol. 473; no. 1; pp. 15 - 19
• Main Authors: Modak, S., Ammar, M., Mazaleyrat, F., Das, S., Chakrabarti, P.K.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 03-04-2009; Elsevier
• Subjects: Chemical synthesis; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Diamagnetism, paramagnetism and superparamagnetism; Exact sciences and technology; Magnetic measurements; Magnetic properties and materials; Magnetic properties of nanostructures; Physics; Scanning and transmission electron microscopy; X-ray diffraction; 75.50. Tt; X-ray diffraction; Magnetic measurements; Scanning and transmission electron microscopy; 76.80. +y; Chemical synthesis; 75.30. Cr; Particle size; Magnetic hysteresis; Superparamagnetism; XRD; Scanning and transmission electron; Magnetic particles; Ferrites spinels; Transmission electron microscopy; Ferrimagnetism; Coercive force; microscopy; Coprecipitation; Nanocrystal; Saturation magnetization; Magnetic properties
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2008.06.020

Nanocrystalline Ni
0.4Zn
0.4Cu
0.2Fe
2O
4 samples with different particle sizes are prepared by simple co-precipitation method. The mixed spinel phases of the nanocrystalline materials have been confirmed by X-ray diffractograms (XRD). The sizes of the nanoparticles are estimated from the (3
1
1) peaks of the XRD patterns using Debye–Sherrer equation and are lying in the range of 7–32
nm. High-resolution TEM observations also support the findings obtained from XRD. Specific saturation magnetizations measured by vibrating sample magnetometer (VSM) are found to increase steadily with the increase of average particle size. Nature of variations of the magnetization curves of the different particle sizes samples are of typical superparamagnetic behaviours up to 16
nm beyond which ferrimagnetic ordered particles are dominating over superparamagnetic particles. The coercive field for a sample of particle size 12
nm is interestingly low (87
A/m) where the saturation magnetization is also moderately high (∼50
A
m
2/kg). The coercive fields of the different samples obtained from low frequency hysteresis loops observations show that even in case of sample with lowest particle size, a small fraction of particles are not relaxed within the experimental time window.