Spectral Studies of the Ferrite System Zn0.5Cu0.5AlxFe2−xO4
TL;DR: In this paper, the properties of Zn0.5Cu 0.5Al with respect to a paramagnetic phase C (quadrupole doublet ΔE) were analyzed using Mossbauer, X-ray and infrared spectra.
Abstract: Ferrite samples of Zn0.5Cu0.5Al
x
Fe2−x
O4, 0≤x≤1 were studied using Mossbauer, X-ray and infrared spectra. Mossbauer spectra taken at room temperature show signs of relaxation for all samples. The obtained spectra were analysed into two Zeeman magnetic patterns assigned to the tetrahedral A- and octahedral B-sites and a paramagnetic phase C (quadrupole doublet ΔE). ΔE and the doublet area, which increase with x and the oxygen parameter u are studied. The quadrupole shift is small and may be ignored within experimental error. The isomer shift of the B-sites increases, with x while that of the A-sites does not change. The hyperfine magnetic field of the A-site (H
A) is higher than that of the B-sites (H
B). H
B decreases for x≤0.8 and increases at x=1 while H
A decreases for x≤0.4 and increases for x>0.4. This behaviour is discussed. The cation distribution has been estimated. The linewidth of the outermost A and B-sites and the calculated magnetization have been studied as functions of x for all samples. The B-sites show a composite pattern that has been successfully analysed into separate components. The obtained hyperfine parameters are discussed. The oxygen parameter, the ionic radius and the metal-oxygen bonds of the A- and B-sites were calculated for all samples. The infrared spectra show three vibration bands υ1, υ2 and υ4. The bands υ1 and υ2 show a shoulder, splitting and increasing overlap. Their behaviour has been discussed as a function of x. They show the same behaviour of magnetization and area ratio as the B- to A-sites. All parameters show a different behaviour at x=0.4, which is assigned to higher fraction of the Cu2+ ions in the A-site at this composition.
Citations
More filters
TL;DR: The realism of single phase cubic spinel creation of the synthesized ferrite samples was studied by the DTA-TGA, XRD, SEM, EDX, FT-IR, VSM and dielectric measurements.
106 citations
TL;DR: In this paper, a nanocrystalline Mg0.5Zn0.4 ferrites have been synthesized by sol-gel auto ignition method using X-ray diffraction (XRD).
51 citations
TL;DR: In this paper, the synthesis of chromium doped Ni-Mg ferrite with a chemical formula Ni0.5Mg0.0 in a step of 0.2 was investigated.
45 citations
TL;DR: In this paper, the spinel ferrites Zn0.35Ni0.65−xCoxFe2O4, 0≤x≤1, have been prepared using the standard ceramic technique.
41 citations
TL;DR: A series of ferrite samples with the chemical formula Ni 0.7 Zn 0.3 Cr x Fe 2− x O 4 ( x ǫ = 0.0-0.5) were prepared by a sol-gel auto-combustion method and annealed at 600 ǒC for 4h as mentioned in this paper.
33 citations
References
More filters
TL;DR: In this article, the infrared spectra of 7 ferrites of the formula $M{\mathrm{Fe}}{2}{\mathrm {O}}_{4}, where $M$ designates a divalent metal, are presented and analyzed.
Abstract: The infrared spectra of 7 ferrites of the formula $M{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$, where $M$ designates a divalent metal, are presented and analyzed. Electronic absorption was observed in the visible and near-infrared regions. Two absorption bands arising from interatomic vibrations were measured and force constants calculated for the stretching of bonds between octahedral or tetrahedral metal ions and oxide ions. These force constants are in agreement with the elastic and thermodynamic properties of these compounds and are sensitive to distribution of metal ions between the alternate sites. The integrated vibrational band intensities were measured: they are compatible with predominantly ionic bonding for these structures.
1,957 citations
TL;DR: In this article, a new magnetic exchange mechanism was proposed to explain the magnetic properties of spinels, which is consistent with the covalent model of the spinels' magnetic properties.
Abstract: Elastic- and electrostatic-energy considerations are insufficient for an explanation of cation ordering between tetrahedral and octahedral sites in spinels. Tetrahedral, octahedral, and square covalent bonds are also important when cations are to be accommodated in these sites. The square bonds in octahedral sites can cause the tetragonal distortion observed in ${\mathrm{Mn}}_{3}$${\mathrm{O}}_{4}$ $\ensuremath{\gamma}$-${\mathrm{Mn}}_{2}$${\mathrm{O}}_{3}$, Zn${\mathrm{Mn}}_{2}$${\mathrm{O}}_{4}$, Cu${\mathrm{Fe}}_{2}$${\mathrm{O}}_{4}$, Cu${\mathrm{Cr}}_{2}$${\mathrm{O}}_{4}$, Ca${\mathrm{In}}_{2}$${\mathrm{O}}_{4}$, Cd${\mathrm{In}}_{2}$${\mathrm{O}}_{4}$, and metallic indium. A new magnetic exchange mechanism, "semicovalent exchange," which is consistent with the covalent model, is used to explain the magnetic properties of spinels.
534 citations
TL;DR: In this paper, the Mossbauer spectra of Fe 57 in tetragonal and cubic cubic CuFe 2 O 4, CU 0.5 Zn 0.3 Cd 0.
201 citations
191 citations
TL;DR: In this paper, the Yafet-Kittel angles of disordered systems with and without an external magnetic field have been determined using M\"ossbauer spectroscopy.
Abstract: The Yafet-Kittel angles of the disordered system ${\mathrm{Zn}}_{x}{\mathrm{Ni}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ for $0\ensuremath{\le}x\ensuremath{\le}1$ have been determined using ${\mathrm{Fe}}^{57}$ M\"ossbauer spectroscopy with and without an external magnetic field. It is found that for $x\ensuremath{\le}0.5$ the resultant $A$- and $B$-site Fe-spin moments have a collinear arrangement, whereas for $xg0.5$ a noncollinear arrangement of $A$- and $B$-site Fe spin moments exists. The canting angles of the $B$-site Fe moments determined from the applied-field M\"ossbauer spectra are smaller than those deduced from the neutron-diffraction data. An explanation based on the relative strength of the exchange constants ${J}_{\mathrm{AB}}$ and ${J}_{\mathrm{BB}}$ is given to account for this difference. The cation distributions are shown to correspond within experimental error limits to $({\mathrm{Zn}}_{x}{\mathrm{Fe}}_{1\ensuremath{-}x})[{\mathrm{Ni}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{1+x}]{\mathrm{O}}_{4}$ for all values of $x$ in the interval $0\ensuremath{\le}x\ensuremath{\le}1.0$. The systematics of the dependence of the isomer shifts on Zn content are consistent with the variations in crystal chemical-structural parameters and with an increase in the covalence of the ${\mathrm{Fe}}^{2+}$-${\mathrm{O}}^{2\ensuremath{-}}$ bond with decreasing internuclear separation. The variations in the magnetic hyperfine fields at the $A$ -site Fe ions can be understood on the basis of a molecular-field model with distant-neighbor exchange interactions being important at low temperatures. A significant contribution from supertransferred hyperfine interactions must be invoked to understand the systematics of the magnetic hyperfine field at the $B$ -site Fe ions.
184 citations