Synthesis and characterizations of AgI nanoparticles via mechanochemical reaction

Silver iodide (AgI) nanoparticles were prepared by mechanochemical reaction technique (MCR) using silver nitrate (AgNO3) and potassium iodide (KI) as reagents and distilled water as solvent. Mechanochemical reaction involves the mechanical activation of solid-state displacement reactions at low temperatures in a ball mill. AgI nanoparticles with well-defined morphology, size and phase compositions were obtained. TEM images show that the particle size of the AgI nanoparticles decreases as a function of milling time. The powder X-ray diffraction patterns show that they are mixture of gamma- and beta-phases. The superionic phase transition temperature (gamma -> alpha) was slightly decreased after milling. The ionic conductivity shows enhancement with temperature for all samples with the unmilled sample has the highest conductivity (4.12 x 10(-6) S cm(-1)) at room temperature. The growth kinetics for AgI nanoparticles were investigated. Two different values of activation energy were obtained indicated that there were two kind of mechanisms for the growth of AgI nanoparticles. (C) 2010 Elsevier B.V. All rights reserved.