Les Nitrates Basiques Mixtes de Zinc et de Cobalt

Abstract

AbstractThe basic zinc and cobalt nitrates, obtained at 20°C by addition of soda to Zn(NO3)2 or Co(N03)2 solutions (0, 2 M M++/1), have the respective compositions Zn5(OH)8(NO3)2.2 H2O and 4 Co(OH)2.Co1, 25 (OH)1.O (NO3)1, 5 H2O. At 75°C, ZnO and β‐Co(OH)2 are formed.In mixed (Zn, Co)‐solutions, at 20°C and for a reaction time of about 1 hour, the solid solution Zn5‐x‐ Co (OH)8 (NO3)2.2 H2O (1) has only a small existence range and transforms progressively into the mixed basic nitrate 4 Zn1‐x Cox (OH)2. Zn1‐y Co (OH)(NO3) (II)(max. 67% at. Co). For higher percentages, the basic cobalt nitrate phase appears. By aging at 20°C, the solid solution (I) is stabilized up to 48% at. Co, whereas at 75°C, there is formation of Zn1‐x CoxO (max.I% at. Co). In both cases, the mixed basic nitrate (II) ranges approximatively from 50 to 75% at. Co. For cobalt‐rich solutions appears a zone of demixtion between β‐Co(OH)2 and a new mixed basic (Co, Zn)‐nitrate (1, 7 < OH− /Me++ < 1, 8).