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La$_{{1-x}}$Ce$_{{x}}$Fe$_{10.5}$Si$_{2.5}$ ($x$ = 0.2, 0.4, 0.6) 합금의 자기열량 효과 연구
남문철,김경섭,유성초,전범용,유태수 한국물리학회 2016 New Physics: Sae Mulli Vol.66 No.7
The magnetocaloric effect of La$_{{1-x}}$Ce$_{{x}}$Fe$_{10.5}$Si$_{2.5}$($x$ = 0.2, 0.4, 0.6) compounds was investigated. The compounds were prepared by arc-melting of pure elements in stoichiometric proportions on a water-cooled copper hearth under an argon atmosphere. The products were sealed in a fused-silica jacket under vacuum and annealed at 1323 K for two weeks. According to the powder X-ray diffraction patterns, the crystal structure was NaZn13-type structure. Magnetic measurements versus temperature ($T$ = 100 - 300 K) and magnetic field ($H$ = 0 - 1 T) were performed on a vibrating sample magnetometer (VSM). The M($T$) curves for the samples should that all the samples exhibited a ferromagnetic-paramagnetic (FM-PM) phase transition at the Curie temperature: $T_{C}$ = 250, 239, and 230 K for $x$ = 0.2, 0.4, and 0.6, respectively. In addition, the changes in the magnetic entropy ($\Delta S_{M}$) were found to be 1.6, 2.8 and 3.0 J/kg$\cdot$K$^{-1}$ for $x$ = 0.2, 0.4, 0.6, respectively. La$_{{1-x}}$Ce$_{{x}}$Fe$_{10.5}$Si$_{2.5}$($x$ = 0.2, 0.4, 0.6) 합금의 자기열량 효과에 대한 연구를 수행하였다. Arc-melting 방법을 이용하여 다결정체 La$_{{1-x}}$Ce$_{{x}}$Fe$_{10.5}$Si$_{2.5}$($x$ = 0.2, 0.4, 0.6)을 합성하였으며 Ar 분위기 하에서 1323 K의 온도에서 2주동안 열처리를 하였다. X-선 회절 실험에 의하여 구조를 분석하였으며 시료진동형 자력계(VSM)를 이용하여 1 T의 자기장 하에서 자화값의(magnetization behavior) 변화를 100 K에서 300 K의 온도 범위에서 측정하였다. 만들어진 소재의 구조는 NaZn13-type의 구조상을 나타내었다. 소재가 페로상태(ferro-magnetic phase)에서 파라상태(para-magnetic phase)로 상변이가 일어나는 온도 즉 큐리온도는 250 K, 239 K, 230 K ($x$ = 0.2, 0.4, 0.6) 근방으로 각각 관측되었다. 자기 엔트로피 변화의 값, $\Delta$S는 1 T 자기장하의 상변이 온도 근방에서 각각 1.6, 2.8 그리고 3.0 J/kg$\cdot$K$^{-1}$ ($x$ = 0.2, 0.4, 0.6)의 값을 가지고 있음을 관측하였다.
정일현,윤용수,강광남,전종남,전범용 한국공업화학회 1998 응용화학 Vol.2 No.1
The effect of the various operating conditions on the removal of Chrominum and Cyanide from wastewater by using electrolysis with iron anode and aluminum cathode was investigated. The removal efficiency of Cr^6+ and CN were increased as the pH was decreased, as the distance of electrode was decreased the voltage was increased. The optimum conditions for the treatment of Cr^6+ and CN containing wastewater were initial pH 3, 5volt, and the distance of electrode was 1cm, At these conditions, 99.44% of Cr^6+ and 75% of CM were removed.