• Journal of the Korean Magnetics Society
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• v.20 no.4
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• pp.153-159
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• 2010

Magnetic properties of basic rocks samples distributed in the seaside area of Ulleung island were investigated by means of X-ray fluorescence spectroscopy (XRF), M$\ddot{o}$ssbauer spectroscopy and SQUID magnetometer. We found that samples were typical basic rock which had the total amount of iron compounds varies from 10.6 wt% to 14.5 wt% depending on the different regions by XRF. The M$\ddot{o}$ssbauer spectra and magnetic hysteresis behaviors of the samples show ferromagnetic properties due to hematite. Also, temperature dependences of magnetization at applied magnetic field of 1 T for samples show magnetic transitions at 41 K~60 K.

• Journal of Magnetics
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• v.14 no.2
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• pp.93-96
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• 2009

The Mn-substituted M-type Ba-ferrite ($BaFe_{12-x}Mn_xO_{19}$; x = 0, 2, 4, 6) powders were prepared by the HTTD (High Temperature Thermal Decomposition) method. The effect of $Mn^{3+}$ Jahn-Teller ions on the magnetic properties has been studied by x-ray diffraction, vibrating sample magnetometry, and $M{\ddot{o}}ssbauer$ spectroscopy. With increasing Mn substitution, the lattice parameter $a_0$ increases while $c_0$ decreases. The magnetocrystalline anisotropy constants ($K_1$) were determined as 2.9, 2.2, 1.8, and, $1.3{\times}10^6\;erg/cm^3$ for x = 0, 2, 4, and 6, respectively, by the LAS method. We have studied the change of cation distribution by $M{\ddot{o}}ssbauer$ spectroscopy which is closely related to $K_1$.

• Journal of the Korean Magnetics Society
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• v.21 no.1
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• pp.37-41
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• 2011

Fe compounds of scoria samples distributed in Songdang-ri positioning north-eastern area of Jeju island were investigated by means of X-ray diffractometry (XRD) and $^{57}Fe$ M$\ddot{o}$ssbauer spectroscopy. The samples were prepared from six parasite. We found that the samples were composed of a typical olivine, pyroxene, ilmenite, $SiO_2$, anorite and anorthoclase, M$\ddot{o}$ssbauer spectrum of the most scoria samples are shown doublets and sextets of olivine, doublets of pyroxene, ilmenite and silicate minerals. And the valence states of Fe ion of the scoria samples in this area are chiefly 3+ charge state and a little 2+ charge state.

• 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 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.20 no.3
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• pp.246-251
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• 2015

This study was aimed to study the effect of Zn content on the hyperfine parameters and the structural variation of $Ni_{1-x}Zn_xFe_2O_4$ for x = 0, 0.2, 0.4, 0.6, and 0.8. To achieve this, a sol-gel route was used for the preparation of samples and the obtained ferrites were investigated by X-ray diffraction, scanning electron microscopy, and $M{\ddot{o}}ssbauer$ spectroscopy. The formation of spinel phase without any impurity peak was identified by X-ray diffraction of all the samples. Moreover, the estimated crystallite size by X-ray line broadening indicates a decrease with increasing Zn content. This result was in agreement with the scanning electron microscopy result, indicating the reduction in grain growth with further zinc substitution. The room-temperature $M{\ddot{o}}ssbauer$ spectra show that the hyperfine fields at both the A and B sites decreased with increasing Zn content; however, the rate of reduction is not the same for different sites. Moreover, the best fit parameter showed that the quadrupole splitting values of B site increased from the pure nickel ferrite to the sample with x = 0.8.

• Journal of the Korean Magnetics Society
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• v.23 no.2
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• pp.43-48
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• 2013

The Jahn-Teller distortion of chalcogenide $Fe_{0.9}M_{0.1}Cr_2S_4$ (M=Co, Ni, Zn) have been investigated by M$\ddot{o}$ssbauer spectroscopy. The crystal structures of $Fe_{0.9}M_{0.1}Cr_2S_4$ (M=Co, Ni, Zn) are cubic spinel at room temperature. Magnetoresistance measurements indicate these system is conducting-semiconducting transistion around $T_C$. Below $T_C$, the asymmetric line broadening is observed and considered to be dynamic Jahn-Teller distortion. Isomer shift value of the samples at room temperature was about 0.5 mm/s, which means that charge state of Fe ions is ferrous in character. The Ni substitutions for Fe occur to increase the Jahn-Teller relaxation. CMR properties could be explained with magnetic polaron due to Jahn-Teller effect, which is different from both the double exchange interactions of manganite system and the triple exchange interactions of chalcogenide $Cu_xFe_{1-x}Cr_2S_4$.

• Korean Journal of Materials Research
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• v.15 no.6
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• pp.393-398
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• 2005

The crystal structure and magnetic properties of the $Mg_{1-x}Zn_xFeAlO_4\;(0{\leq}x\leq1.0)$ have been investigated by means of x-ray diffractometry and $M\ddot{o}ssbauer$ spectroscopy. The samples$(0{\leq}x\leq1.0)$ have been prepared by the ceramic sintering method. The x-ray diffraction pattern shows that the crystal structure of the samples is a cubic spinel type. The lattice constant has been found by extrapolation using the Nelson-Riley function and it increases slightly from $8.3496\AA\;to\;8.4128\AA$ with Zn concentration. The $M\ddot{o}ssbauer$ spectra for x<0.4 show a superposition of two sextets ana a paramagnetic doublet at room temperature. The superparamagnetic doublet for x<0.4 seems to be due to Al ion in tetrahedral site by the superparamagnetic clustering effect.

• Journal of the Korean Magnetics Society
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• v.18 no.5
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• pp.168-173
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• 2008

Fe compounds of scoria distributed in northern area of Jeju island are investigated using X-ray fluorescence spectroscopy, X-ray diffractometry, and $^{57}Fe$ Mossbauer spectroscopy. The samples were prepared from four parasite volcanos. These samples consist of the typical basalt comprised of $SiO_2,\;Al_2O_3$, Fe compounds, and silicate minerals. The $M{\ddot{o}}ssbauer$ spectra showed doublets for olivine, pyroxene, and ilmenite as well as sextets for hematite and magnetite. The valence state of Fe is chiefly a 3+ charge state with a little 2+ charge state. It is expected that this results will add to the body of information related to the information mechanism of Jeju island. The geochemistry for these samples is the same results to mid-mountain's samples in Jeju Island.

• Journal of the Korean Magnetics Society
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• v.24 no.2
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• pp.46-50
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• 2014

The crystallographic properties and cationic distribution of $M_{0.2}Fe_{2.8}O_4$ (M =Mn, Ni, Cu) and $Fe_3O_4$ thin films prepared by sol-gel method have been investigated by X-ray diffraction (XRD) and conversion electron M$\ddot{o}$ssbauer spectroscopy (CEMS). The ionic valence, preferred site, and hyperfine field of Fe ions of the ferrites could be obtained by analyzing the CEMS spectra. The $M_{0.2}Fe_{2.8}O_4$ films were found to maintain cubic spinel structure as in $Fe_3O_4$ with the lattice constant slightly decreased for Ni substitution and increased for Mn and Cu substitution from that of $Fe_3O_4$. Analyses on the CEMS data indicate that $Mn^{2+}$ and $Ni^{2+}$ ions substitute octahedral $Fe^{2+}$ sites mostly, while $Cu^{2+}$ ions substitute both the octahedral and tetrahedral sites. The observed intensity ratio $A_B/A_A$ of the CEMS subspectra of the samples exhibited difference from the theoretical value. It is interpreted as due to the effect of the M substitution for A and B on the Debye temperature of the site. The relative line-broadening of the B-site CEMS subspectra can be explained by the dispersion of magnetic hyperfine fields due to random distribution of M cations in the B sites.