| 摘要 |
PURPOSE:To improve the specific surface area of the titled Si-contg. powder in a process for production consisting in coating Si-contg. needle crystal alpha-FeOOH particles in which dendrite particles do not exist mixedly with P and Si compd. then subjecting the particles to dehydration and reduction by heating by incorporating Cr, Ni and Mg into said particles. CONSTITUTION:A prescribed amt. of water soluble silicate is added to exist in a suspension contg. the Fe(OH)2 obtd. by the reaction between both aq. solns. of ferrous salt and alkali and having >=11pH and an O2-contg. gas is passed therethrough to obtain Si-contg. needle crystal alpha-FeOOH particles. Water soluble Cr, Ni and Mg salts are preliminarily added to either of the above-described two aq. solns. and suspension at 0.1-5.0, 0.1-7.0, 0.1-15.0atom% expressed in terms of respective elements with respect to Fe. The needle crystal alpha-FeOOH particles contg. Si, Cr, Ni and Mg are thus obtd. Such particles are suspended in water to form the particles coated with P and Si compd. under prescribed conditions and the particles are subjected to reduction by heating after dehydration by heating, by which the titled powder for a video is obtd. |
