Abstract:
The present research work is focused Ytterbium (Yb) doped Co-Zn ferrites. The
ferrite samples of the composition Co0.25Zn0.75YbxFe2-xO4 [where x = 0.00, 0.02, 0.04,
0.06 and 0.08] were prepared by standard solid state reaction technique. The samples
were pre-sintered at 850°C for 2 hours and sintered at 1150°C for 3 hours. The effect
of rare earth Yb3+ substitution on the structural, magnetic and electrical properties of
the Co-Zn ferrites was studied. The Phase identification and lattice parameter
determination were carried out by using X-ray diffraction (XRD). XRD patterns
showed that all the samples consisted of the singe phase cubic spinel structure with no
extra peak. The lattice parameters gradually increased with increasing Yb content.
The bulk density slightly decreased with increasing rare earth Yb3+ ion and the X-ray
density increased continuously with increasing x-content. The microstructural
analysis was done by Scanning Electron Microscopy (SEM). The SEM images
showed that the sample exhibit uniform surface morphology with well-defined
spherical grains. The average grain size was calculated using Image J software and
observed that the average grain size increases with Yb content. The complex
permeability, loss tangent and dielectric properties were investigated as a function of
frequency range 1 KHz to 120 MHz by using an impedance analyzer. The initial
permeability was found in steady state to a higher order of frequency range from
103Hz - 50 MHz. Continuous decrease of the dielectric constant with the increasing
frequency and remains almost constant at higher frequency range has been observed.
The magnetic properties have been studied by Vibrating Sample Magnetometer
(VSM). The saturation magnetization (Ms), coercivity (Hc), remanent magnetization
(Mr), Bhor magneton (μB), and anisotropy constant (Ku) have been calculated from the
M-H loop at room temperature. The values of Ms were decreased with increasing
Yb3+ content. Coercivity was increased with Yb content except for X = 0.08 where it
decreased. The values of μB were found to be decreased with increasing Yb3+content.
Doping of Yb ion lowers the conduction and subsequently an increase in resistivity is
observed. The characteristics of electromagnetism, excellent chemical stability,
mechanical hardness, high coercivity, and moderate saturation magnetization have
made Yb doped Co-Zn ferrite a good candidate for synthesizing and investigation to
contribute in science and technology.
Description:
This thesis is submitted to the Department of Physics, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Physics, October 2018.
Cataloged from PDF Version of Thesis.
Includes bibliographical references (pages 69-75).