http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Young Rang Uhm,Sam Jin Kim,Chul Sung Kim 한국자기학회 2002 Journal of Magnetics Vol.7 No.1
The charge structures of La_(0.6)Sr_(0.4)FeO₃ (LSMO) and of the combined system (La_(0.6)Sr_(0.4)MnO₃)_(0.7)(La_(0.6)Sr_(0.4)FeO₃)_(0.3) are investigated by using Mossbauer spectroscopy. The antiferromagnetically ordered La_(0.6)Sr_(0.4)FeO₃(LSFO) has possible charges of Fe³+ and Fe⁴+, which include a low-spin Fe⁴+ state at and above 230 K. The temperature dependences of the Mossbauer spectra for the La_(0.6)Sr_(0.4)FeO₃ system and for the combined (LSMO)_(0.7)(LSFO)_(0.3) system are fitted as three sets of Zeeman patterns corresponding to Fe³+ and Fe⁴+ below 230 K. At and above 230 K, the fitted Mossbauer spectra for the combined system are the same in all temperature ranges. Above 230 K, La_(0.6)Sr_(0.4)FeO₃ spectrum consists of two sets of six Lorentzians for Fe³+ and one line for low spin Fe⁴+. It is worth noting that large fields are induced in the combined system.
Fe–Nx active sites in Fe–N–C electrocatalysts synthesized using electron beam irradiation
Uhm Young Rang,Sun Gwang Min,Lee Jaegi,Kim Chul Sung,Park Ji Hyun,Ha Taesung 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.3
Fe–N–C catalysts synthesized by the electron beam (e-beam) irradiation pyrolysis of Fe and N precursors is studied owing to their remarkable activities in the electrochemical oxygen reduction reaction (ORR). The conditions for Fe–Nx formation were confrmed by irradiation at 80 kGy under an e-beam energy of 10 MeV and a beam current of 800 μA. The coordination between Fe and each phenanthroline (phen) isomer (1,7-phen, and 1,10-phen) was efectively controlled by molecular structures of monodentate, and bidentate. The pyridinic N % was found to be 70.1% for Fe (1,10-phenanthroline)/KB prepared by e-beam irradiation pyrolysis. This catalyst exhibited superior ORR activity and stability in alkaline half-cells. The use of precursors with bidentate coordination is important to obtain the efective inducement of Fe–Nx active sites for electrocatalysts during ORR.
Provenance Studies for Prehistoric Obsidian by Using Mössbauer Spectroscopy
Uhm Young Rang,Sun Gwang-Min,Jin Mi-Eun,Jwa Yong-Joo,Seo Jae Yeon,Choi Hyunkyung,Kim Chul Sung 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.3
The iron compounds in minerals of obsidians from the continental Far East, Mount Baekdu (Baedusan) near the Sino-Korean border and Kyushu in southwest Japan were studied using 57Fe Mössbauer spectroscopy. The mineral Pyroxene (FeSiO3) in obsidian was found in the metamorphic rocks of Mount Beakdusan and Kyushu. However, the mineral biotite in obsidian was found in Kyushu only. The chemical compounds of the microlites in obsidians from Mount Baekdu are quite different from those in the Kyushu obsidians. The Mössbauer spectrum measured on the Baekdusan obsidian was fitted using two sextets, two ferrous iron doublets, and a ferric iron doublet tentatively assigned to clinopyroxene. Two sextets result from the nonstoichiometric magnetite. In contrast, Kyushu obsidians consisted of two sextets, a ferrous iron doublet for clinopyroxene, and a ferric iron doublet tentatively associated with biotite. In mineralogical and geochemical studies on the Baekdusan and Kyushu obsidians, the origination of the magma compositions and the crystallization environments were confirmed to have been different.