Study of room temperature dc resistivity in comparison with activation energy and drift mobility of NiZn ferrites

doi:10.1016/j.mseb.2004.12.086

Materials Science and Engineering: B

Volume 118, Issues 1–3, 25 April 2005, Pages 132-134

https://doi.org/10.1016/j.mseb.2004.12.086 Get rights and content

Abstract

Ni_xZn_1−xFe₂O₄ ferrites, for x = 0.66, 0.77, 0.88 and 0.99, have been produced by standard ceramic solid-state reaction method using locally available low cost Fe₂O₃, having few wt% of Si to improve the resistivity of ferrite samples. Electrical resistivity was measured and then used to calculate activation energy and drift mobility of all the samples. Room temperature dc resistivity increases by increasing Ni content. Temperature dependent dc resistivity decreases with increasing temperature from 30 to 180 °C while mobility increases by increasing temperature and decreases by increasing ρ. It is found that the samples having higher values of resistivity also have higher values of activation energies and vice versa.

Introduction

NiZn ferrites are soft ferromagnetic materials having low magnetic coercivity and high resistivity values and small eddy current losses in high frequency operation. High electrical resistivity and good magnetic properties make these ferrites an excellent core material for power transformers in electronics, recording heads, antenna rods, loading coils, microwave devices and telecommunication applications [1].

Ferrites have higher resistances than metals by several orders of magnitude and they are also regarded as very structure-sensitive materials [2]. It is a well-known fact that the properties of ferrite materials are strongly influenced by the materials composition and microstructure, but, in addition, the sintering conditions employed and the impurity levels present in or added to these materials also change their properties [1], [3], [4], [5], [6], [7].

The electrical resistance can be improved further by using different techniques, like special sintering conditions and selecting suitable composition with small amount (a few mol%) of metal oxide additions in ferrites [3], [4], [5], [8].

The literature survey [1], [3], [4], [8] indicates that optimum properties are obtained for NiZn ferrites sintered at 1200–1250 °C. These ferrites fired at 1250 °C show dependence of the resistivity on Zn content and an interesting plateau structure, that Ni and Zn ferrites are inhibiting each other's principal conduction mechanism. Also, there is great improvement in resistivity made by grinding the surface, which is due to the fact that some of the surface Zn is distilled off the specimen during firing, leading to the presence of surface Fe²⁺ which is then removed by the grinding process. Some other researchers [3], [4], [5], [6], [7], [9], [10], [11], [12] investigate the effect of different additives on the properties of NiZnFe₂O₄ ferrites, some additives of which improve the temperature dependence of μ_i, spin–spin relaxation time and some increases the magnetic susceptibility and resistivity.

The present work reports the study of room temperature dc resistivity in comparison with activation energy and drift mobility of NiZnFe₂O₄, using low cost Fe₂O₃, having some wt% of Si to improve the resistivity of ferrite samples. The addition of Si is carried out in order to introduce the influence of grain boundary phases that are non-magnetic and also affect the grain growth, consequently increasing the resistivity [5], [6], [7].

Ferrite samples with compositions Ni_xZn_1−xFe₂O₄, where x = 0.66, 0.77, 0.88 and 0.99, were prepared in polycrystalline form by high temperature solid-state reaction method. The compositions, Ni_xZn_1−xFe₂O₄, were prepared from powder mixture of oxides (NiO and ZnO) of purity better than 99% along with locally available cheap Fe₂O₃ with some wt% of Si as an impurity. The powder mixtures were pressed into pellets of 16 mm diameter under uni-axial pressure of 3.5 tonnes. Initially the samples were sintered in a muffle furnace at 1000 °C for prolonged period and finally heated for 6 h at 1200 °C for making a homogenous product. The samples were quenched in air and X-ray diffraction (XRD) patterns were taken to identify the phases formed and to confirm the completion of the chemical reaction by using Rigaku XRD D/MAX-IIA diffractometer using Cu Kα radiation with scanning speed of 1° (2θ/min), as reported elsewhere [13]. In the present work, the surface of the pellets were cleaned by grinding on SiC paper in order to remove any contamination and then used to study the room temperature dc resistivity, measured by two probe-method in comparison with activation energy and drift mobility of NiZnFe₂O₄.

Section snippets

Results and discussion

All the four compositions of Ni_xZn_1−xFe₂O₄ ferrites with x = 0.66, 0.77, 0.88 and 0.99 produced by solid-state reaction method, sintered at 1200 °C [1], [3], [4], [5], [8], have been analyzed by XRD. The details of the samples as phases with confirmation of completion of ferrite structure are given elsewhere [13].

Room temperature dc resistivity of all these samples was measured by two probe-method and is plotted in Fig. 1, as a function of Ni content. It has been observed that the resistivity (ρ)

Conclusions

1.
Sintering the composition at 1200 °C, using a small proportion of Si as impurity and grinding the surface of the pellets improve the values of resistivity for Ni_xZn_1−xFe₂O₄ ferrites.
2.
Room temperature resistivity increases by increasing Ni content.
3.
The samples having high resistivity have higher activation energies and vice versa.
4.
The temperature dependent mobility increases with the increase of temperature whereas resistivity decreases, this may be attributed to the semi conducting behaviour of the

References (18)

A.C.F.M. Costa et al.
J. Magn. Magn. Mater.
(2003)
K.H. Wu et al.
J. Magn. Magn. Mater.
(2004)
A. Verma et al.
Mater. Sci. Eng.
(1999)
N. Rezlescu et al.
Ceramic Int.
(1987)
M.U. Islam et al.
Mater. Chem. Phys.
(1997)
N. Rezlescu et al.
J. Magn. Magn. Mater.
(2000)
G. Joshi et al.
Solid State Commun.
(1988)
M. El-Shabasy
J. Magn. Magn. Mater.
(1997)
M. Sugimoto
J. Am. Ceram. Soc.
(1999)

There are more references available in the full text version of this article.

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Study of room temperature dc resistivity in comparison with activation energy and drift mobility of NiZn ferrites

Abstract

Introduction

Section snippets

Results and discussion

Conclusions

J. Magn. Magn. Mater.

J. Magn. Magn. Mater.

Mater. Sci. Eng.

Ceramic Int.

Mater. Chem. Phys.

J. Magn. Magn. Mater.

Solid State Commun.

J. Magn. Magn. Mater.

J. Am. Ceram. Soc.