Abstract
Ultrafine cobalt-substituted iron oxide particles were prepared by the thermal decomposition and oxidation of the new organometallic precursor, $Co_xFe_{1-x}(N_2H_3COO)_2(N_2H_4)_2$ (x = 0, 0.01, 0.02, 0.03, 0.05, 0.10, 1.00). The organometallic precursors were synthesized by the reaction of Co(II) and Fe(II) ion in a mole ratio of x : 1-x with hydrazinocarboxylic acid, and characterized by quantitative analysis, elemental analysis and infrared spectroscopy. The mechanistic study on the thermal decomposition of the organometallic precursors was performed by TG-DTG and DSC. The cobalt-substituted iron oxide particles were obtained by the heat treatment of the precursors at $350^{\circ}C$ and $450^{\circ}C$ for six hours in air. The prepared iron oxide was found to have two phases such as ${\gamma}-Fe_2O_3$ and a mixture of ${\gamma}-Fe_2O_3\;and\;{\alpha}-Fe_2O_3$ at $350^{\circ}C$ and $450^{\circ}C$ respectively. The particle shape was equiaxial and the particle size was less than 0.05 ${\mu}m.$ The coercivity and squareness of the cobalt substituted iron oxide particles increased with increasing cobalt content. Both coercivity and squareness showed higher values at $450^{\circ}C.$
초미립 코발트 치환 산화철 분말을 새로운 유기금속 전구체인 $Co_xFe_{1-x}(N_2H_3COO)_2(N_2H_4)_2$ (x = 0, 0.01, 0.02, 0.03, 0.05, 0.10, 1.00)을 열분해화 산화과정으로 제조하였다.유기금속 전구체는 몰비 x : 1-x인 Co(II)와 Fe(II)를 hydrazinocarboxylic acid와 반응시켜서 합성하였고, 합성을 정량분석, 및 적외선분광기를 사용하며, 합성을 정량분석, 원소분석 및 적외선분광기를 사용하여 확인하였다. 유기금속 전구체의 열분해 과정은 TG-DTG 와 DSC로 살펴보았다. 코발트치환 산화철 분말은 유기금속 전구체를 대기 중에서 $350^{\circ}C$ 와 $450^{\circ}C$에서 6시간 열처리하여 제조하였다. 산화철의 결정상은 각각 ${\gamma}-Fe_2O_3$ 및 ${\gamma}-Fe_2O_3$ 와 ${\alpha}-Fe_2O_3$의 혼합상이었다. 입자의 형태는 구형에 가까운 모양이었고 크기는 $0.05{\mu}m$ 이하의 초미립이었다. 코발트 치환 산화철의 보자력과 각형비는 코발트 함량 또는 열처리 온도가 높아질 수록 증가하였다.