The Effect Of Annealing On The Structure Of Ag Aggregates Deposited On Ionic Liquid Substrates

Silver aggregates, deposited on ionic liquid surfaces, have been fabricated and annealed at different temperatures Ta. The morphological evolution and microstructure of the aggregates are studied systematically. The results are exhibited as follows:(1) The samples are composed of ramified aggregates and quasi-circular aggregates. It can be found that, after annealing,the width of the ramified aggregates diminishes and the structure of the quasi-circular aggregates become loose. The coverage of total aggregates p decreases after annealing. When298K<Tα<773K, the decrease ratio of p, namely Δρ/ρ, increases from2%to35%first, and then decreases to21%, the critical Ta is around573K. For Tα>573K, a phenomenon can be found that Δρ/ρ of the ramified aggregates is higher than Δρ/ρ of the quasi-circular aggregates. It is suggested that the phenomenon described above should be related to the weak structural stability and strong diffusivity of the ramified aggregates.(2) The AFM experiment shows that the aggregates are composed of a large number of nanoparticles (NPs). For298K<Tα<573K, both the average height of Ag aggregates and the diameter of the NPs increase with Tα, and the quasi-circular aggregates are quite dense after annealing. We propose the behaviors of the system mainly result from the characteristic microstructure of the samples.(3) The crystal structure of Ag aggregates has been observed by TEM. It is found that the crystallinity of the samples increases with the annealing temperature. Our observations suggest that the translation of the structure from bcc-like to fcc-like almost finishes when Ta increases to573K. For Tα>573K, the NPs grow by coalescing with each other. In addition, there occurs some small particles during annealing.The thesis is organized as follows:In chapter I, the current status of thin films is introduced, and we also give a brief review of the main procedures and the influences of annealing. Furthermore, the features of crystalline and amorphous thin films are compared.In chapter Ⅱ, the used equipments and the steps of this experiment are showed.In chapter Ⅲ, the influences which annealing makes on the microstructure and morphology features of samples are studied systematically, and then we speculate the evolution mechanism of the coverage with Tα.In chapter Ⅳ, the main conclusions are summarized.