الفهرس 
Chapter 1 IntroductionOnly 14 pages are availabe for public view
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Abstract
The structure and magnetic properties of the chemical composition
Mn1-xCuxFe1.7Ga0.3O4 (x = 0, 0.25, 0.5, 0.75 and 1) were studied for all
samples synthesized using two different techniques, standard solid-state
reaction method and sol- gel method, also the cation distribution for the
two samples (MnFe2O4 and CuFe2O4) were determined . XRD data
showed that, all the samples have the cubic spinel structure except two
samples (CuFe2O4 and CuFe1.7Ga0.3O4) where found a tetragonal
structure. The lattice parameter increases with increasing copper content
x. FTIR spectra showed that, two modes have appeared at (482-399) and
(745-599) cm-1 corresponding to υ1 and υ2, respectively. These bands are
assigned to the vibrations of the tetrahedron and octahedron for the
trivalent (Fe3+) cation respectively. First mode is attributed to the
stretching vibrations of tetrahedrally coordinated Fe3+-O2− bonds and
second mode is attributed to the metal oxygen vibrations in the octahedral
sites (B).
The Mӧssbauer spectra at room temperature for Mn1-xCuxFe1.7Ga0.3O4
were decomposed into two components-Zeeman sextets, due to the Fe
ions in the oxidation state Fe3+, in both A- and B-sites of the spinel
structure. In addition to these two sextets, the spectra show a quadrupole
doublet in the compound Mn1-xCuxFe1.7Ga0.3O4. This doublet may be due
to the ferrite CuFeO2, which is paramagnetic at room temperature. The
isomer shifts of A-sites are slightly larger than those of B-sites except for
the sample (CuFe1.7Ga0.3O4). In contrast the internal magnetic fields of Asites are slightly smaller than those of B-sites.
The cation distribution were found as (Cu0.1Fe0.9) [Cu0.9 Fe1.1] ,
(Mn0.7Fe0.3) [Mn0.3 Fe1.7] for the simple ferrite samples where parenthesis
refers to the tetrahedral A-site and square bracket refers to the octahedral
B-site.
The saturation magnetization (MS) in samples prepared using solid
state reaction was found (from 14.071 to 46.122 emu/g). We found that,
MS increases with Cu content up to x = 0.5 and then gradually decreases
with further increase of Cu content and for samples prepared using solgel method was found (17.949 to 39.963 emu/g).
Also the observed moments were compared to the theoretically calculated
moments according to Néel model and depending on different possible
cation distribution. The results clearly suggest that Ga3+ cation distributed
in both A site and B- sites and this was in agreement with the Mӧssbauer
data.