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김철성 한국물리학회 2005 새물리 Vol.50 No.2
The analysis techniques for nano technology require new analytical characterization systems, based on quantum mechanical principle, in addition to present microscopic analysis systems. Even though nano technology is fundamentally very important, there are some prerequisites for its applications. First, a thorough understanding of the interactions between nano-sized structures is required. Second, suitable measurement and analysis techniques for nano systems must be developed and must be complimentary. Mossbauer spectroscopy is a microscopic characterization tools that satises the Heisenberg uncertainty principle and that can resolve and energy of 10က12 eV and a time of 10က7 s. In this work, we introduce Mossbauer spectroscopy and dicuss, an a case-by-case basis, trends in its applications to nano materials.
Investigation of the Magnetic Properties of Ni0.7Fe0.3Ga2S4
김철성,명보라,김삼진 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.3
We have studied the magnetic properties of Ni0.7Fe0.3Ga2S4 with Fe substituted at the Ni sites by using an X-ray diffractometer (XRD), a superconducting quantum interference device (SQUID)magnetometer, and a M¨ossbauer spectrometer. The polycrystalline sample of Ni0.7Fe0.3Ga2S4 is found to be a single phase of the trigonal structure with a space group of P-3m1. The structural parameters of the sample are obtained by using a Reitveld refinement with lattice constants of a0 = 3.640 °A and c0 = 12.020 °A. The bond length between Fe and S ions is about 2.420 °A,which suggests a short-range ordering with the frustration effect. From the M¨ossbauer spectra, the magnetic hyperfine field and the electric quadrupole interaction are estimated to be Hhf = 124.2kOe, and EQ = 2.10 mm/s, respectively, at 4.2 K. The charge state of the Fe ions is ferrous (Fe2+) from the value of the isomer shift, δ = 0.66 mm/s, at room temperature. The spin quantum number of Ni0.7Fe0.3Ga2S4 is determined to be S = 3/2, while it is S = 1 for NiGa2S4 and S = 2for FeGa2S4. This indicates an increase an spin-orbital interactions with increasing Fe.