Effect of Resistivity, Permeability and Curie temperature of Rare Earth ...

VOL. 5, NO. 10, October 2015

ISSN 2225-7217

ARPN Journal of Science and Technology ©2011-2015. All rights reserved. http://www.ejournalofscience.org

Effect of Resistivity, Permeability and Curie temperature of Rare Earth Metal Europium (Eu) Substitution on Ni0.60Zn0.40-XEux Fe2O4(X=0.05, 0.10, 0.15) Ferrites 1

M. A. Hossain, 2M. N. I. Khan, 3S. S. Sikder

1

Department of Physics Khulna University of Engineering and Technology, Khulna, Bangladesh 2 Materials Science Division, Atomic Energy Center, Dhaka, Bangladesh 3 Department of Physics Khulna University of Engineering and Technology, Khulna, Bangladesh 1 [email protected] , [email protected] , [email protected]

ABSTRACT Rare earth metal Europium (Eu) substituted Ni–Zn ferrites of composition Ni0.60Zn0.40-xRexFe2O4 where x=0.05, 0.10, 0.15 have been prepared by the Conventional Solid State Reaction Method. The samples were pre sintered at 1000 0C for 4 hours in air and sintered at 1250 0 C for 3 hours. The influence of Europium (Eu) substitution on electrical and magnetic properties of Ni-Zn ferrites have been studied in this work. Investigations were carried out by the measurements of AC resistivity, Permeability and Curie temperature of the sample. AC resistivity has been found to be decreased of the samples. The initial magnetic permeability remains constant up to 10 MHz for content x=0.05 , 20MHz for content, x=0.10 and for content x = 0.15 it is 30 MHz thenceforth sharply fall to very low at higher frequencies and constant onward due to Zn deficient of Ni -Zn ferrites with substituting of Eu. The sharp directress of permeability at T = T c indicates the samples good homogeneity. The TC is found to increase with increasing Zn-deficient by substituting rare earth metal Europium (Eu). Keywords: Conventional solid state reaction method, sintering, resistivity, permeability, curie temperature and rare earth metal

1. INTRODUCTION At the beginning of the industrialization, iron and its alloys were used as magnetic materials to serve the need of the electrical industry. With the advent of higher frequencies, the standard techniques of reducing eddy current losses, using lamination or iron powder cores, were no longer efficient or cost effective. This realization stimulated a renewed interest in “Magnetic Insulators” as first reported by S. Hilpert in Germany in 1909. By 1945 Snoek had laid down the basic fundamentals of the physics and technology of practical ferrite materials [1]. In 1948, the Neel theory of ferromagnetic provided the theoretical understanding of this type of magnetic material. Polycrystalline soft ferrites prepared from metal oxides are magnetic semi conductors and have made important contribution, both technological and conceptual to the development of electronics. Soft ferrites still remain the best magnetic materials and cannot replaced by any other magnetic materials with respect to their very high frequency application because they are inexpensive, more stable, easily manufactured [2].The most important advances were made in ferromagnetism in the field of magnetic oxides (ferromagnetic). Due to their remarkable behavior of magnetic and electric properties they are subjects of intense theoretical and experimental investigation for application purpose [3-16].

2. RELATED WORK The advancement of high frequency ferrites was initiated by the work done by J. L. Snoek [17], who found that associated with excellent properties in the high frequency range, Mn-Zn and Ni-Zn ferrites provide a family of magnetic materials useful for radio and TV sets as well carrier telephony as cores of inductors transformer

and so forth. The most popular combination are Ni-Zn [18], Ni-Cu-Zn [19-21], Mg-Zn [22] and Mg-Cu-Zn [23] a ferrites. Ferrite crystallizes with two magnetic sub-lattices i.e. tetrahedral (A) site and Octahedral (B) site based on Neel’s model. Magnetic and electrical properties of ferrites are strongly dependant on distribution of cation in A and B sites and their valance state [24]. The properties of Ni-Zn ferrites can be tailored by substitutions them with different metals ions such as Co2+,Mg2+,Mn2+,Cu2+etc. The addition of rare earth metal in Ni-Zn ferrite composition is known to play a crucial role in increasing the sintering density and lowering the sintering temperature. Various additives such as V2O5, Bi2O3, PbO, MoO3, WO3, E2O3 P2O5, La2O3, W2O3, LiO etc. having low melting point, facilitated to reduce the sintering temperature of these oxides materials due to liquid phase either due to the melting of the additives or due to the eutectic liquid phase formation between the additives and the ferrite. Amount of liquid phase increase with increasing amount of sintering aids which results in increased densification. However excessive amount of sintering additives’ will deteriorate electromagnetic properties of the ferrite. So, optimum content of sintering aids is necessary to achieve good sinter ability as well as better electromagnetic properties. Till now researches have not yet been able to formulate a rigid set of rules for ferrites about a single property. Among these La 2O3,Y2O3 and E2O3 were the most effective sintering for Ni-Zn ferrite the systematic research is still necessary for effects has been under taken to prepare Ni-Zn ferrite doped with La2O3,Y2O3 and Eu2O3. Scientists still continue their efforts to find out optimum parameters of ferrites, like high saturation magnetization, high permeability, high resistivity, etc. In the present research work we prepared Ni0.60Zn0.40-xEux Fe2O4 (x=0.05, 0.10, 0.15) Ferrites. We studied the variation of electrical 520


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resistivity and magnetic permeability in both temperature and frequency dependent cases. 2.1 Experimental Conventional Solid State Reaction Method: In the solid state reaction method, the required composition is usually prepared form the appropriate amount of raw mineral oxides or carbonates by crushing, grinding and milling. The most common type of mill is the ball mill but instead of ball mill we performed it by hand millig. Milling can be carried out in a wet medium to increase the degree of mixing. This method depends on the solid state interdiffusion between the raw materials. In 1965 Carter and Kooy [25-26] made careful studies of the position of inter markers in diffusion couples and computed that the counter diffusion essentially involves the movement of cations through a more or less rigid lattice of oxygen anions. Solids do not usually react at room temperature over normal time scales. Thus it is necessary to heat them at higher temperatures for the diffusion length (2Dt)1/2 to exceed the particle size, where D is the diffusion constant for the fastdiffusing species, and t is the firing time. The ground powders are then calcined in air or oxygen at a temperature above 10000C. For some time, this process is continued until the mixture is converted into the correct crystalline phase. The calcined powders are again crushed into fine powders. The tablet and ring shaped samples are prepared from these calcined powders using hydrostatic pressure. Pre sintering is carried out at temperature 10000C for (3) three hours and sintering at the temperature 1250 0 C for (4) four hours. The general solid state reaction leading to a ferrite MFe2O4 may be represented as MO + Fe2O3

MeFe2O4 where M is the divalent ions

2.2 Table of 20 gm compositional details of Ni0.6Zn0.4xEuxFe2O4 [x = 0.05, 0.10, 0.15] ferrites Content,x

NiO

ZnO

Eu2O3

Fe2O3

2. 3 A flow chart of preparation of sample is presented below

As a whole the preparation procedure generally consists of four major steps:    

Preparing a mixture of materials with the cations in the ratio corresponding to that in the final product. Pre-firing the mixture to form ferrite. Converting the raw ferrite into powder and pressing the powder and pressing the powder into the required shapes. Sintering to produce a highly densified product.

3. RESULTS AND DISCUSSION Table 1: Resistivity at room temperature of Ni0.60 Zn0.40-x EuxFe2O4 ferrites

Content,x

0.05

3.707

2.356

0.728

13.209

0.05

Resistivity at room temperature (300C) 224.19

0.10

3.636

1.980

1.428

12.956

0.10

23.247

0.15

32.393

0.15

3.567

1.620

2.101

12.712

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ARPN Journal of Science and Technology ©2011-2015. All rights reserved. http://www.ejournalofscience.org 250

200

Eu

Fe O

Ni Zn

Eu

Fe O

Ni Zn

Eu

Fe O

0.6

0.6

150

Resistivity

Ni Zn

0.6

100

0.35

0.30

0.25

0.05

0.10

0.15

2

2

2

4

4

4

50

0

0

100

200

300

400

500

Temperature

Figure-2 describes the change of permeability with the change of frequency. For sample Ni0.60 Zn0.35 Eu0.05 Fe2 O4, it is seen that the initial permeability is as same as up to a very high frequency 10 MHz i.e., initial permeability is constant up to 10 MHz thenceforth the initial permeability sharply decreases up to 100MHz after that it remains constant on wards. At high frequency greater than 100 MHz the permeability becomes frequency independent. For sample Ni0.60 Zn0.30 Eu0.10 Fe2 O4 the initial permeability is constant up to a very high frequency 20 MHz thereafter the initial permeability gradually decreaseds up to 100MHz and for sample Ni0.60 Zn0.25 Eu0.15 Fe2 O4, it is seen that the initial permeability is constant up to 30 MHz and then gradually decreases up to 100 MHz. After that it becomes almost frequency independent.

Figure 1: Temperature dependence of resistivity, as a function of Temperature of Ni 0.60 Zn0.35 Eu0.05 Fe2 O4, Ni0.60 Zn0.30 Eu0.10 Fe2 O4, and Ni0.60 Zn0.25 Eu0.15 Fe2 O4, sintered at 12500C

600

550

500

Ni Ni

450

Ni

Zn

0.60

Zn

0.60

Zn

0.60

Eu

0.35

Eu

0.30

Eu

0.25

Fe O

0.05

2

4

Fe O

0.10

2

4

Fe O

0.15

2

4

In figure -1 the rectangular black sign indicates the sample Ni0.60 Zn0.35 Eu0.05 Fe2 O4.The curve of sample Ni0.60 Zn0.35 Eu0.05 Fe2 O4 shows that with increasing the temperature from room temperature the resistivity decreasing up to 1800C. After that with increasing the temperature the resistivity becomes constant and almost temperature independent. In figure-1 the circle shaped red sign indicates Ni0.60 Zn0.30 Eu0.10 Fe2 O4 which indicates that with increasing the temperature the resistivity decreasing up to 1850 C and becomes constant and almost temperature independent onward. In figure-1 triangular blue sign indicates sample Ni0.60 Zn0.25 Eu0.15 Fe2 O4 which shows that with increasing temperature the resistivity decreasing gradually and after 1900C becomes almost temperature independent. All the samples show the nature of the semiconductor.

Figure 2: Frequency dependence of the real part of the permeability, as a function of frequency of Ni0.60 Zn0.35 Eu0.05 Fe2O4, Ni0.60Zn0.30Eu0.10Fe2O4 and Ni0. 60Zn0.25 Eu0.15Fe2O4 sintered at 12500C

Permeability

400

350

300

250

200

150 0

100

200

300

400

500

Temperature

Figure 3: Temperature dependence of the real part of the permeability, as a function of Temperature of Ni 0.60 Zn0.35 Eu0.05 Fe2O4, Ni0.60Zn0.30 Eu0.10Fe2O4 and Ni0.60Zn0.25 Eu0.15Fe2O4 sintered at 12500C Curie temperature Tc is the basic quantity in the study of magnetic materials. It corresponds to the temperature at which a magnetically ordered materials becomes magnetically disordered i.e. becomes paramagnetic. Curie temperature also signifies the strength of the exchange interaction between the magnetic atoms. The black line sign at the top of the graph indicates sample Ni0.60 Zn0.35 Eu0.05 Fe2 O4 graph. With increasing the temperature the domain of the sample tends to align parallel to each other. When all the domain align parallel to each other completely then the last limit of ferromagnetic material reach which indicate the homogeneity of the sample and with further increase of temperature permeability of the sample sharply break down which is shown in figure-3 sample Ni0.60 Zn0.35 Eu0.05 Fe2 O4. At temperature 3200C the permeability sharply breaks down and, this break down temperature is known as Curie temperature. The red line sign at the bottom of the curves indicates the graph of sample Ni0.60 Zn0.30 Eu0.10 Fe2 O4. The sharply break down points of this sample Ni0.60 Zn0.30 Eu0.10 Fe2 O4 is 3460C. The green line sign at the middle of the curves indicates the graph o the sample Ni0.60 Zn0.25 Eu0.15 Fe2 O4. The sharply break down points of the sample Ni0.60 Zn0.25 Eu0.15 Fe2 O4 is 4160C.This Curie temperature indicates the single phase of the studied samples. After Curie temperature the domains of the ferromagnetic materials align in random directions as a result the 522


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ferromagnetic materials.

materials

change

into

paramagnetic

Ts = 12500C

Zn-content. There is much scope for further research in controlling the magnetic characteristics by changing composition and heat treatment certain important parameters like temperature dependence magnetization, anisotropy and magnetostriction can be study in detail for a better understanding of micro structure properties of the samples.

Tc0C

REFERENCES

2.1 Ni0.60Zn0.35Eu0.05Fe2O4

320

2.2 Ni0.60Zn0.30Eu0.010 Fe2O4

346

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2.3 Ni0.60Zn0.25Eu0.15Fe2O4

416

Table 2: Data of Curie temperature (TC) (Ni0.60 Zn0.40-x EuxFe2O4) Zn- deficient content , x

[2] J. Kulikowski;1”Soft magnetic ferrites development of stagnation”; J. Magn. Magn. Matter; Vol. 41 p.5662, 1984 [3] M. M. Haque,"Influence of additives on the magnetic and electrical Properties of iron excess Mn-Zn ferrite ",M.Phil Thesis,BUET,Bangladesh (2000).

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Curie temperature,T

380

360

340

320

0.04

0.06

0.08

0.10

0.12

0.14

0.16

Content,x

Figure 4: Curie temperature dependence of the content, as a function of temperature of Ni0.60 Zn0.35 Eu0.05 Fe2O4, Ni0.60Zn0.30Eu0.10Fe2O4 and Ni0.60Zn0.25Eu0.15Fe2O4 sintered at 12500C Figure-4 shows the variation of Curie temperature, Tc with Zn deficient. Curie temperature mainly depends upon the strength of A-B exchange interaction.

4. CONCLUSION Effect of magnetic and electrical properties of NiZn ferrites has studied thoroughly on the Europium (Eu) substitution on Ni0.60Zn0.40-x Eux Fe2 O4 (x=0.05, 0.10, 0.15) Ferrites. Temperature dependence resistivity was measured to identify the nature of the samples. Initially resistivity decreases gradually at lower temperature region, while after a certain temperature it decreases sharply and at high temperature region it becomes almost independent of temperature. Frequency dependant permeability was studied to fathom the frequency response initial permeability. Temperature dependence permeability has been used to measure the Curie temperature of Ni0.60Zn0.40-x Eux Fe2 O4 (x = 0.05, 0.10, 0.15) Ferrites. Curie temperature of Ni-Zn ferrite increases with the decrease in

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AUTHOR PROFILES M. A. Hossain received his M.Sc. Degree in Physics from Jahangirnagar University (JU), Savar Dhaka, Bangladesh. Currently, he is working as a lecturer Department of Physics, Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh. M.N.I Khan received his Ph.D. Degree from Tohoku University , Japan. Currently he is working as a senior scientific officer in Material Science division, Bangladesh Atomic Energy Commission Center Dhaka, Bangladseh. S.S. Sikder received his Ph.D. Degree from University of Dhaka, Bangladesh. Currently he is working as a Professor, Department of Physics, Khulna University of Engineering & Technology (KUET), Khulna9203, Bangladesh.

[23] M.A Hakim, M. Manjurul Haque, M. Huq, Sk. Manjura Hoque and P. Norbblad; “Reentrant Spin Glass Behavior of Diluted Mg-Zn Ferrites”; CP

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