• Journal of the Korean Magnetics Society
• /
• v.7 no.5
• /
• pp.232-236
• /
• 1997

We have gone into details about the velocity calibration of sinusoidal mode for Mossbauer spectrometer. Since sinusoidal Mossbauer spectrometer has a ${\gamma}$-ray source that oscillates at the end of loudspeaker with the natural frequency. Doppler velocity is accurate and stable. From the analyzing Mossbauer spectra of $Fe_3O_4$ and U $Fe_3O_4$ (unbalanced $Fe_3O_4$), we have shown the power of correct velocity for sinusoidal mode.

• Korean Journal of Materials Research
• /
• v.6 no.11
• /
• pp.1107-1112
• /
• 1996

Ni를 Cd로 대치시켜 세라믹 소결법으로 합성한 Ni0.8Cd0.2Fe2O4 의 X-ray 회절선을 측정하여 구조를 확인하고, 형성된 결정체의 격자 상수를 조사하였다. 이 시료의 Mossbauer 스펙트럼을 80K-900K의 온도 영역에서 측정 분석하여 Mossbauer parameter의 온도 의존성과 Fe 이온에 대한 자료를 얻고, 이 자료를 토대로 Ni0.8Cd0.2Fe2O4 의 자기 전이 현상과 Curied 온도 Tc와 격자 비열 및 Debye 온도와 같은 물성을 조사하였다.

• The Journal of Natural Sciences
• /
• v.7
• /
• pp.19-25
• /
• 1995

In this study, the Mossbauer effect of the $NiAl_0.8Fe_1.2O_4$ was investigated in the temperature range of 77K-1000K. The spectra were composed of two component, one is sixtet and the other doublet, at low temperature. From the temperature dependence of Mossbauer spectum, it is appeared that the magnetic properties of $NiAl_0.8Fe_1.2O_4$ varies from ferrimagnetism to paramagnetism as the increasing tempereture. And the magnetic relaxation patterns of the $NiAl_0.8Fe_1.2O_4$ were shown superparamagnetic effect.

• Journal of the Korean Magnetics Society
• /
• v.10 no.4
• /
• pp.183-190
• /
• 2000

This study aims at making a research into the physical and chemical properties of the neolithic era potterys, which are unearthed from Gosanli, Sagaeli, Bukchonli, Samyangdong and Gonaili districts in Cheju Island, by using X-ray diffraction, X-ray fluorescence spectrometer and Mossbauer spectroscopy. This results are as follows. The principal component of five plain coarse pottery sherds by X-ray fluorescence spectrometer and X-ray diffraction spectrum at the room temperature is silicate mineral which is equal to SiO$_2$, and they also have a little magetite, hematite and goethite. The most existent Fe is Fe$\^$+3/ through Mossbauer spectroscopy analysis of plain coarse pottery sherds and it is presumed that the magnetic hyperfine splitting caused this result. The ratio of Fe$\^$2+//(Fe$\^$2+/+Fe$\^$3+/) is mostly zero by Mossbauer spectrum at the room temperature of plain coarse pottery sherds and it is thought because they were fired in the atmosphere.

• Proceedings of the Korean Magnestics Society Conference
• /
• 1991.11a
• /
• pp.22-23
• /
• 1991

• Proceedings of the Korean Magnestics Society Conference
• /
• 2000.09a
• /
• pp.453-454
• /
• 2000

• Journal of the Korean Vacuum Society
• /
• v.6 no.4
• /
• pp.337-342
• /
• 1997

We have investigated Mossbauer effect and emission properties of the Fe-doped GaAs grown by liquid phase epitaxy (LPE). The powder type of isotope $^{57}Fe$ was used as a dopant source in LPE-GaAs. From the analysis of Mossbauer effect the value of isomer shift, 0.303$\pm$0.018 mm/sec, is calculated at low temperature. This means that charge state of Fe ion in GaAs is 3+. The results of double crystal x-ray rocking curve (DCRC) and low temperature photoluminescence (PL) show the crystal quality of the epitaxial layers are good. Unusual luminescence peaks from the Fe-GaAs epitaxial layers appeared at emission energy of 0.99 eV and 1.15 eV. We attribute these emissions to Fe-acceptor related two deep radiative centers.

• Korean Journal of Materials Research
• /
• v.5 no.7
• /
• pp.808-815
• /
• 1995

The magnetic states of nonstoichiometric substituted ferrite Fe$_{}1.429$(Al$_{4-x}$ Ga$_{x}$)$_{0.286}$ Si$_{0.143}$ /O$_4$ system have been investigated using Mossbauer spectroscopy and SQUID. The Mossbauer spectra at room temperature show well-defined two Zeeman patterns for x=0.2, superpositions of two Zeeman patterns and a doublet for x=0.4. The doublet peak seems to be originated from the superparamagnetic clusters. The system shows significant departures from the Neel's collinear model and seems to be the diluted ferrites. The Mossbauer spectra below R.T show various and complicated patterns, which can be explained by freezing of the superparamagnetic clusters. On cooling, magnetic states of the system may be various and multicritical, Resulting from SQUID measurements, there was an unexpected dip in magnetization curves below 50K. It was interpreted as an effect of spin canting including spin freezing or collective spin behavior.

• Journal of Powder Materials
• /
• v.9 no.5
• /
• pp.341-345
• /
• 2002

Nanoparticles of $Fe_2O_3$ with a mean particle size of 4-30 nm have been prepared by a pulsed wire evaporation method, and its structural and magnetic properties were studied by SQUID magnetometer and Mossbauer spectroscopy. From the main peak intensity of XRD and absorption rate of Mossbauer spectrum, the amounts of $\gamma-Fe_2O_3$ and $\alpha-Fe_2O_3$ in as-prepared sample are about 70% and 30%, respectively. The coercivity (53 Oe) and the saturation magnetization (14 emu/g) are about 20% of those of the bulk $\gamma-Fe_2O_3$. The low value of coercivity and saturation magnetization indicate that the $\gamma-Fe_2O_3$ phase nearly shows the spin glass-like behavior. Analysis of the set of Mossbauer spectrum indicates a distribution of magnetic hyperfine fields due to the particle size distribution yielding 20 nm of average particle size. The magnetic hyperfine parameters are consistent with values reported of bulk $\gamma-Fe_2O_3$ and $alpha-Fe_2O_3$. A quadrupole line on the center of spectrum represents of superparamagnetic phase of $\gamma-Fe_2O_3$ with a mean particle size of 7 nm or below.

• Journal of Powder Materials
• /
• v.14 no.2 s.61
• /
• pp.97-100
• /
• 2007

The magnetic alloys of Cu-Fe ($Cu_{50}Fe_{50},\;Cu_{80}Fe_{20}\;and\;Cu_{90}Fe_{10}$) were prepared by a mechanical alloying method and their structural and magnetic behaviors were examined by X-ray diffraction and Mossbauer spectra. The magnetization curves did not distinctly show the saturation at 70 kOe for the concentrated alloys of $Cu_{80}Fe_{20}\;and\;Cu_{90}Fe_{10}$. The Mossbauer spectrum of $Cu_{80}Fe_{20}$ at room temperature shows one Lorentzian line of the paramagnetic phase, whereas the Mossbauer spectrum of $Cu_{90}Fe_{10}$ consists of sextet Lorentzian line at room temperature and a centered doublet line. The Mossbauer spectra of $Cu_{90}Fe_{10}$ measured in the temperature ranges from 13 to 295 K, implies that $Cu_{90}Fe_{10}$ to consists of two magnetic phases. One superimposed sextet corresponds to the ferromagnetic iron in Cu and the other one indicates the superparamagnetic iron rich phase.