Preparation, characterization and thermal behavior of silver behenate nanocrystals

Abstract

Silver behenate nanocrystals were first prepared by chemical precipitation in a water tert-butyl alcohol mixed solvent. The influence of main factors on the silver behenate crystal size was studied. The morphology, crystal structure and thermal behavior of silver behenate nanocrystals were investigated using SEM, TEM, XRD, IR and TG-DTA. These results showed that the preparation method, reaction temperature and excessive silver ion concentration in reaction solution played important roles in determining the size of silver behenate nanocrystals. The prepared silver behenates were scaly crystals with a mean diameter of about 70 nm. The silver behenate nanocrystals possessed layer structure. A series of structural changes of silver behenate nanocrystals were observed at different temperatures. The silver behenate nanocrystals had excellent thermal stability below 120°C. At high temperature there were two distinct transitions resulting in dramatic structural changes. In the first transition at 138°C, the alkyl chains of silver behenate were transformed from an ordered into a disordered state. In the second transition at 230°C, a completely irreversible structural change took place due to the decomposition of silver behenate nanocrystals.