| abstract |
At least one basic precipitant selected from the group consisting of NaOH, KOH, NH 4 OH, NH 3 , NH 4 HCO 3 and (NH 4 ) 2 CO 3 until the equivalent weight of the basic precipitant reaches 0.5 to 3 equivalents. The solution is added to an indium salt solution containing 0.1 to 3 M of indium at an addition time within 24 hours while maintaining the temperature at 5 to 95 ° C. The precipitate obtained from the solution by solid-liquid separation is then dried and calcined at a temperature of 570-780 ° C. in a non-oxidizing atmosphere containing ammonia gas and water vapor.n n n Indium, indium salt solution, basic precipitant, ammonia gas, water vapor |