Preparation of Ultrafine AgX Particles by Solid-Phase Reaction at Room Temperature

Nanophase silver halides were synthesized firstly by solid-phase reactions of AgNO₃ with KX （X=Cl^-, Br^-, I^-） at room temperature. Their structures,particle sizes, morphology and heat stability were characterized with XRD, TIM and TG/DTA techniques. It was found that the colour of nanophase AgX synthesize by solid-phase reactions is different from that of normal AgX synthesized in aquous solution, and their particle sizes d prepared under the same conditions decrease in the sequence: d_AGCl＞d_AGBr＞d_Agl. The results of DTA curves of nanophase AgI and nounal AgI indicated that their transform temperatures of crystalline form from a-AgI to β-AgI are almost similar but their phase transform temperature from solid-state to liquid-state differ greatly. The melt point of nanophase AgI is much lower than that of nounal AgI.