• Journal of Magnetics
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• v.2 no.4
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• pp.116-122
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• 1997

To determine whether there is an ionic substitution of Ni, Co, Mn, and Al for Fe in synthetic goethites these materials have been studied by M$\ddot{o}$ssbauer spectroscopy at various temperatures ranging from 77 to 400 K. It is found that the presence of substituting elements in magnetically ordered structure of crystals may change the shape of M$\ddot{o}$ssbauer spectra of these caterials. The approximate distribution function of the effective magnetic field in the Fe nucleus p(Hn) is obtained from the M$\ddot{o}$ssbauer spectra. It is noted that the mean value of p(Hn) and its integral width can be taken as a measure of substitution in goethites.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.1
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• pp.62-66
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• 1998

M$\ddot{o}$ssbauer spectra of ferrimagnetic $Fe_2SE_8$ prepared with $^{57}Fe$ enriched iron have been taken at 298 K and below 78K, and Fe\ulcornerSe\ulcorner has been studied by X-ray diffraction. The crystal structure is found to be a "3c" hexagonal superstructure of the NiAs structure. Three sets of six-line hyperfine patterns were obtained and assigned to three magnetically nonequivalent sites of a superstructure of the crystal. The iron ions at all three sites are found to be in a highly covalent ferrous state. It is shown that the results obtained at the low temperature region are well consistent with Okazaki's "3c" superstructure model.uperstructure model.

• Journal of the Korean Ceramic Society
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• v.48 no.1
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• pp.34-39
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• 2011

Systematic study on relationship between celadon coloring and glaze component was conducted by chromaticity analysis and M$\ddot{o}$ssbauer spectroscopic analysis. The chromaticity ($L^*$, $a^*$, $b^*$ values) and M$\ddot{o}$ssbauer analysis results were correlated to the amount of $Fe_2O_3$, $TiO_2$, MnO, and $P_2O_5$, which are the essential factors influencing celadon coloring. According to chromaticity analysis, celadon glaze color belongs to GY group when the addition of $TiO_2$ was 1.4%, whereas the color belongs to BG group when the addition of $TiO_2$ was 0.1%. For the GY group, the colors change from GY to YR with the decrease of brightness as the addition of $TiO_2$, MnO, and $P_2O_5$ increases. According to M$\ddot{o}$ssbauer analysis results, as the amount of divalent iron ion increases, the $a^*$ and $b^*$ values decrease, on the other hand, $L^*$ value increases. The ratio of divalent iron ion produced in reductive sintering process is found to be 80~95% in this study, which induces the increase of $L^*$ values in celadon glaze.

• Journal of Magnetics
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• v.13 no.3
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• pp.110-113
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• 2008

In this study, heavy rare earth garnet $Tb_2Bi_1Ga_1Fe_4O_{12}$ powders were fabricated by a sol-gel and vacuum annealing process. The crystal structure was found to be single-phase garnet with a space group of Ia3d. The lattice constant $a_0$ was determined to be 12.465 ${\AA}$. From the analysis of the vibrating sample magnetometer (VSM) hysteresis loop at room temperature, the saturation magnetization and coercivity of the sample are 7.64 emu/g and 229 Oe, respectively. The N$\acute{e}$el temperature($T_N$) was determined to be 525 K. The M$\ddot{o}$ssbauer spectrum of $Tb_2Bi_1Ga_1Fe_4O_{12}$ at room temperature consists of 2 sets of 6 Lorentzians, which is the pattern of single-phase garnet. From the results of the M$\ddot{o}$ssbauer spectrum at room temperature, the absorption area ratios of Fe ions on 24d and 16a sites are 74.7% and 25.3%(approximately 3:1), respectively. These results show that all of the non-magnetic Ga atoms occupy the 16a site by a vacuum annealing process. Absorption area ratios of Fe ions are dependent not only on a sintering condition but also on the temperature of the sample. It can then be interpreted that the Ga ion distribution is dependent on the temperature of the sample. The M$\ddot{o}$ssbauer measurement was carried out in order to investigate the atomic migration in $Tb_2Bi_1Ga_1Fe_4O_{12}$.

• Journal of the Korean Magnetics Society
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• v.26 no.6
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• pp.213-218
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• 2016

This study reviewed mineral composition on Scoria samples of this area, atomic value state of oxidized steel, and magnetic property in order to look into characteristics of scoria that was distributed in southern area of mountainous areas, Halla Mt. of Jeju Island. By XRD analysis, mineral composition was confirmed, and characteristics of iron compounds existed in samples were investigated through $M{\ddot{o}}ssbauer$ spectroscope. Composing minerals could be learnt as feldspar basalt from XRD analysis because composting minerals were composed of quartz and feldspar anorite mainly, and iron compounds were made up with olivine, pyroxene, ilmenite, hematite, and magnetite. By $M{\ddot{o}}ssbauer$ spectroscope analysis on these iron compounds. it consisted of hematite and magnetite which showed hyperfine magnetic field of sextet mostly, and also doublet by olivine, pyroxene, ilmenite could be seen as appearing together. As a result of comparing with samples of Jeju western area having been announced in previous research, I.S. and Q.S. values of olivine, $Fe^{2+}$, were 122 mm/s and 3.09~3.13 mm/s respectively, and a fact could be known that $Fe^{2+}$ olivine having similar structure each other was contained, and the ratio of $Fe^{3+}/Fe_{tot.}$. was 85.90~92.82 %. From these findings, it was able to be presumed that they belonged to samples having been formed on the land at the same period of time. As a result of investigating area ratio of tetrahedron (A site) and octahedron (B site) regarding magnetite in samples, it was turn out to be 0.22~0.55 less than 2.

• Journal of Magnetics
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• v.17 no.2
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• pp.83-85
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• 2012

Magnetic particles in a novel, wound-healing ointment were studied using M$\ddot{o}$ssbauer spectroscopy and VSM to estimate the stability of the properties of the magnetic particles. The isomer shifts of $Fe_3O_4(A)$ were found to be 0.49-0.56 mm/s relative to iron metal, this indicates that the iron ions in $Fe_3O_4(A)$ are $Fe^{3+}$. On the other hand, the isomer shifts of $Fe_3O_4(B)$ were found to be 0.91-1.13 mm/s relative to iron metal, this shows that the ion state of $Fe_3O_4(B)$ is a mixed state of $Fe^{2+}$ and $Fe^{3+}$. It is noted that this composition, as well as that of the initial pure component in the form of a highly dispersed fraction (${\sim}10\;{\AA}$), differs from the stoichiometric one. It was found that the area ratio of the M$\ddot{o}$ssbauer subspectra of $Fe_3O_4(A)$ / $Fe_3O_4(B)$ taken at 87 and 181 K linearly increased in comparison to the initial pure magnetic particles, but the rate of increase of the area ratio at 181 K was about two times that at 87 K. From the magnetic hyperfine field, despite their small size, the particles exhibit no superparamagnetism.

• Journal of Magnetics
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• v.15 no.1
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• pp.25-28
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• 2010

This study examined the crystallographic and magnetic properties of vanadium-substituted lithium cobalt titanium ferrite, $Li_{0.7}Co_{0.2}Ti_{0.2}V_{0.2}Fe_{1.7}O_4$. Ferrite was synthesized using a conventional ceramic method. The samples annealed below $1040^{\circ}C$ showed X-ray diffraction peaks for spinel and other phases. However, the sample annealed above $1040^{\circ}C$ showed a single spinel phase. The lattice constant of the sample was $8.351\;{\AA}$, which was relatively unaffected by vanadium-substitution. The average grain size after vanadium-substitution was $13.90\;{\mu}m$, as determined by scanning electron microscopy. The M$\ddot{o}$ssbauer spectrum could be fitted to two Zeeman sextets, which is the typical spinel ferrite spectra of $Fe^{3+}$ with A and B sites, and one doublet. From the absorption area ratio of the M$\ddot{o}$ssbauer spectrum, the cation distribution was found to be ($Co_{0.2}V_{0.2}Fe_{0.6})[Li_{0.7}Ti_{0.2}Fe_{1.1}]O_4$. Vibrating sample magnetometry revealed a saturation magnetization and coercivity of 36.9 emu/g and 88.6 Oe, respectively, which were decreased by vanadium-substitution.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1708-1711
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• 2018

The polycrystalline sample of $Ba_2Co_{1.5}Mg_{0.5}Fe_{11.88}Ga_{0.12}O_{22}$ Y-type hexaferrite, doped with Ga-cation, was prepared by using the solid-state reaction method. The crystalline structure of sample was investigated by x-ray diffractometer (XRD), and the magnetic properties of sample were measured by vibrating sample magnetometer (VSM), and $M{\ddot{o}}ssbauer$ spectrometer. The crystal structure of prepared sample was determined to be rhombohedral with space group R-3m. From the temperature dependence of the magnetization curves under 100 Oe between 4.2 and 740 K, two temperature-dependent magnetic transitions occurred in the $Ba_2Co_{1.5}Mg_{0.5}Fe_{11.88}Ga_{0.12}O_{22}$ sample. $M{\ddot{o}}ssbauer$ spectra of the sample were analyzed at various temperatures ranging from 4.2 to 620 K, and the $Ba_2Co_{1.5}Mg_{0.5}Fe_{11.88}Ga_{0.12}O_{22}$ sample showed abrupt changes in $H_{hf}$ and $E_Q$ at 200 K, indicating the spin transition effect. We have also determined the magnetic transition temperature $T_C$, in addition to the temperature dependent magnetization and ZVC measurements.

• Journal of Magnetics
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• v.21 no.1
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• pp.40-45
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• 2016

Nickel substituted nano-sized ferrite powders, $Co_{1-x}Ni_xFe_2O_4$, $Mn_{1-x}Ni_xFe_2O_4$ and $Mn_{1-2x}Zn_xNi_xFe_2O_4$ ($0.0{\leq}x{\leq}0.2$), were fabricated using a sol-gel method, and their crystallographic and magnetic properties were subsequently compared. The lattice constants decreased as quantity of nickel substitution increased, while the particle size decreased in $Co_{1-x}Ni_xFe_2O_4$ ferrite but increased for the $Mn_{1-x}Ni_xFe_2O_4$ and $Mn_{1-2x}Zn_xNi_xFe_2O_4$ ferrites. For the $Co_{1-x}Ni_xFe_2O_4$ and $Mn_{1-x}Ni_xFe_2O_4$ ($0.0{\leq}x{\leq}0.2$) ferrite powders, the $M{\ddot{o}}ssbauer$ spectra could be fitted as the superposition of two Zeeman sextets due to the tetrahedral and octahedral sites of the $Fe^{3+}$ ions. However, the $M{\ddot{o}}ssbauer$ spectrum of $Mn_{0.8}Zn_{0.1}Ni_{0.1}Fe_2O_4$ consisted of two Zeeman sextets and one single quadrupole doublet due to the ferrimagnetic and paramagnetic behavior. The area ratio of the $M{\ddot{o}}ssbauer$ spectra could be used to determine the cation distribution equation, and we also explain the variation in the $M{\ddot{o}}ssbauer$ parameters by using this cation distribution equation, the superexchange interaction and the particle size. The saturation magnetization decreased in the $Co_{1-x}Ni_xFe_2O_4$ and $Mn_{1-2x}Zn_xNi_xFe_2O_4$ ferrites but increased in the $Mn_{1-x}Ni_xFe_2O_4$ ferrite with nickel substitution. The coercivity decreased in the $Co_{1-x}Ni_xFe_2O_4$ and $Mn_{1-2x}Zn_xNi_xFe_2O_4$ ferrites but increased in the $Mn_{1-x}Ni_xFe_2O_4$ ferrite with nickel substitution. These variations could thus be explained by using the site distribution equations, particle sizes and spin magnetic moments of the substituted ions.

• Journal of the Korean Magnetics Society
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• v.17 no.5
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• pp.205-209
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• 2007

It have been investigated the measured results of the XRF, the X-ray diffractometry and $^{57}Fe\;M{\ddot{o}}ssbauer$ spectrum for scoria samples which are distributed throughout different areas in Mid-mountain Area of Jeju island. We consider that the scoria samples are chiefly made of silicate minerals, like $SiO_2$, others silicate minerals and iron oxides minerals. We study that it's materiel is consisted of olivine, pyroxene, ilmenite, hematite and magnetite. Iron compounds in that are $Fe^{2+}$ of olivine, pyroxene, ilmenite and $Fe^{3+}$ of hematite, magnetite et al. The major Fe fractions of the scoria samples are 51.77 wt%, so Fe fractions of the scoria samples are almost 3+ charge state with a little of the 2+ charge state.