Synthesis and Characterization of Copper Substituted Lithium Nano Ferrites by Sol-Gel Auto combustion

In this work sol-gel method used for preparing nanoscale iron oxide ferrites dopant by copper and lithium, which carries the chemical formula Li1-xCuxFe5O8 where x is the added ratio as molar ratio (x = 0,0.1,0.2,0.3,0.4,0.5,0.6 and 1), during the selfcombustion for sol-gel which happen at temperature of 200 o C, after that the samples were divided into four groups , the first group namely that have not been annealed while the other groups ; the second, third and fourth were annealed at 500 o C , 700 o C and 900 o C respectively. In this work the crystalline structure have a dominate phases which have been studied by using the X-ray diffraction as well as Kirkuk University Journal /Scientific Studies (KUJSS) Volume 12, Issue 2, March 2017 ISSN 1992 – 0849 Kirkuk University Journal /Scientific Studies (KUJSS) Volume 12, Issue 2, March 2017 ISSN 1992 – 0849 examination of the electron microscope and examine the infrared mediated model of Fourier Transform Infrared Spectrometer either the topography of the surface has been studied by using an atomic force microscope, examine the properties of electrical capacitive mediated capacitance measuring device, resistance and the inductor also studied. And indirectly through these tests was to know the size of the structural unit of the crystal density theory and fixed lattice, as well as the size of the grain has been measured by X-ray diffraction, while a microscopic blocs have checked mediated electron microscopy scan scanner, either measuring the size of the granules on the surface of the sample and the coefficient of roughness has been measured mediated by an atomic force microscope and the type of bonds that bind atoms in the crystal and the type of crystalline eccentric may checked mediated infrared while measuring the properties of capacitive and portability electrical conductivity of the alternating current it may have been mediated by checking capacitive properties. he current study focuses on measuring the properties of capacitive, which takes into account the effect of changing the copper content in the samples and the degree of sintering temperature as well as the change altered applied to the samples from the external voltage source, as well as the loss of electric power when the power is in the passage of the samples

examination of the electron microscope and examine the infraredmediated model of Fourier Transform Infrared Spectrometer either the topography of the surface has been studied by using an atomic force microscope, examine the properties of electrical capacitive mediated capacitance measuring device, resistance and the inductor also studied.
And indirectly through these tests was to know the size of the structural unit of the crystal density theory and fixed lattice, as well as the size of the grain has been measured by X-ray diffraction, while a microscopic blocs have checked mediated electron microscopy scan scanner, either measuring the size of the granules on the surface of the sample and the coefficient of roughness has been measured mediated by an atomic force microscope and the type of bonds that bind atoms in the crystal and the type of crystalline eccentric may checked mediated infrared while measuring the properties of capacitive and portability electrical conductivity of the alternating current it may have been mediated by checking capacitive properties.
he current study focuses on measuring the properties of capacitive, which takes into account the effect of changing the copper content in the samples and the degree of sintering temperature as well as the change altered applied to the samples from the external voltage source, as well as

1.Introduction:
Nano crystalline spinel ferrites have been investigated in the recent years by many researchers. Ferrite is a polycrystalline, magnetic components, they have low magnetic losses properties therefore its an excellent soft magnetic spinel ferrites, low dielectric losses, high mechanical hardness, high Curie temperature and high chemical stability.
They play a useful role in many technological applications such as the electronic and telecommunication industries and because of their high initial permeability the nano ferrites are used in high density information storage devices. Depending on type of applications, magnetic ferrite nano particles are used in varieties of forms such as surface functionalized particles in biomedical applications, particles arrays in magnetic storage media and compacted powders in permanent magnets ferrite can be used at considerably high frequencies sintered material with high electrical resistively. The high resistance of ferrite resistivity, makes eddy current losses extremely low at high frequencies [1].
The spinel ferrite structure with the chemical formula KFe 5 O 8 , where K refers to the monovalent metal, can be described as a cubic close-packed arrangement of oxygen atoms, with K 1+ and Fe 3+ at two

2.The Raw Materials:
The Li (1-x) Cu x Fe 5 O 8 Nano ferrite samples were manufactured with a raw materials, the selected materials were very pure as mentioned in the table (1): The Nano ferrite samples were manufactured within the past listed raw materials in special procedure and conditions , the procedure were repeated to manufacture (23) Nano ferrite samples arranged in four groups ,the first group has the samples with copper molar ratio x=

Dielectric Constant
In the Nano ferrite sample series, the variation of the dielectric constant of the composite with frequency is calculated in equation (1)  Maxwell and Wagner two-layer model [3]. the Nano ferrite tablets act as multilayer capacitor, the space charge polarization is produced in a dielectric material due to the presence of higher and poorer electrical conductivity phases where they're the structure of the dielectric material, the grains of the Nano ferrite samples are the higher electrical conductivity phases and they're acted as the capacitor conductive slabs.
When an external electric field is applied [4]. and then reaches a constant value. It is due to the fact that beyond a certain frequency of external field, the electrons exchange Fe 2+ ↔ Fe 3+ cannot follow the alternating field so the polarizability is become independent on the frequency [5]. The Dielectric constant ( ' r ) has a large value at the lower frequency. That happen due to the predominance of species like Fe 2+ ions, the grain boundary defects and the interfacial voids. The decreasing of dielectric constant in presence of ferric ions Fe 3+ , creates lower hopping sites [6]. Therefore the electron pile-up at the grain boundaries tends to decrease. In addition, the Fe 3+ ions are stated to be less polarizability than the Fe 2+ ions. These effects are the main causes which shift the real dielectric constant curves to lower values. it was found that,

Dielectric Loss Factor
The data on the dielectric loss factor (tan δ) relates between the real and imaginary dielectric constants, it's the tangent of the phase lag angle between the two types of the dielectric constants and mainly used in A.C. power and in the telecommunications,the loss factor is an important role to determine the losses made within the flow of A.C. current in which they turn to heat by creating the eddy currents inside the conductive medium , it was studied by the effects of calcination conditions, E.M.F frequency and Cu additions on the lossy characteristics of the Cu-Li ferrite samples [7]. The values of dielectric loss factors were obtained directly by the LCR meter in the test . Figures (4) and (5)   The effect of polarization is to reduce the field inside the medium. it was found that, the composite samples with x=0.0 shows a rapid decreasing in tan δ ( the electrical loss factor) which was equal to 1.253974 when the tablet calcination temperature was 700 ͦ C and equal to 1.205202 when the tablet calcination temperature was 900 ͦ C when the maximum tan δ is observed when the jumping or hoping frequency of electrons between Fe 2+ and Fe 3+ becomes approximately equal to the frequency of the applied field, so at when the tablet calcination temperature was 700 ͦ C the tablet is less conductive then the calcined tablet at 900 ͦ C.

Imaginary Dielectric Constant
It is clear that all the ferrite composite samples under study exhibit the imaginary dielectric constant ( " r ) decrease as the frequency increases up to 5 MHz. Figures (6) and (7) shows clarify the behavior of the imaginary dielectric constant as a function of the frequency in which they were obtained by equation (2) "r = tanδ * 'r ………..  The imaginary dielectric constant ( " r ) is found to decrease faster than ( ' r ) in the lower frequency region, while the variation in ( " r ) is the same as ( ' r ) in higher frequency region. it was found that, the composite samples with x=0.0 shows the higher  " r which was equal 22.71200132 when the tablet calcination temperature was 700 ͦ C and equal to 18.47125 when the tablet calcination temperature was 900 ͦ C.

A.C. Conductivity
The A.C. conductivity (σ AC ) test detects the ability of the conductor to transfer the eddy currents in which they cause electrical energy losses , the more A.C. conductivity the more electrical losses and  place between ions of the same element present in more than one valence state. Such ions are distributed randomly over crystallographically equivalent lattice sites and, in Li-Cu ferrites, the electronic hopping between Fe 2+ and Fe 3+ ions located on octahedral sites is the primary mechanism which allows electrical transport [11], in further comparison, it was found that the composite samples with x=0.0 shows a rapid increasing in σ AC which was equal 0.000234 moh/cm when the tablet calcination temperature was 700 ͦ C and equal to 0.000116191 moh/cm when the tablet calcination temperature was 900 ͦ C . This is due to the existence of a maximum value of the divalent iron Fe 3+ ions and Cu ions mixed together among all the mixed Li-Cu spinel ferrite in the composite samples .At high frequencies i.e. 1000 KHz to 5 MHz ,the value of A.C. conductivity were hesitant in random values with a very small differential ranges for all compositional nano ferrite tablets ,while the  ' r ,  " r and tan δ were begun to be constant in these frequency period, this may be related to the hopping of charge carriers could not follow the applied field in the same applied frequency resulting in hesitant in the A.C. conductivity values and it could be solved by shaping the tablets with different diameters and thicknesses with repeating the A.C. conductivity test to the new dimensions to deal with the higher frequencies.