| SrTiO3 is a kind of important ferroelectric material with perovskite type structure. Because of it's excellent ferroelectric and dielectric properties, SrTiO3 has been most intensively studied recent years. This material has been widely used, such as in high frequency sensitive microwave device, also it shows great potential in non-volatile random accessed dynamical memory application. In order to decrease or prohibit the diffusions between SrTiO3 and other materials, sol-gel technique or low temperature PVD, such as sputtering, is adapted to prepare thin films of it, which often results in amorphous state. For the sake of applying its special properties, the films must be crystallized by followed annealing process. The structure and kinetic characteristics of amorphous state is essential to be studied for better understanding of the crystallizing process, such as the micro-mechanism, the kinetic characteristics, the movements of atoms or ions, and so on.Along with the development of scientific calculation, computer simulation has become an important scientific research technique and has been used in various fields. Comparing with laboratory research technique, computer simulation had many advantages. Within various computer simulation methods, Molecular dynamics (MD) is an important one and has been most widely used. MD has the advantages of real dynamics of the simulated system, the easy access and analysis of exactly moving trajectory of any atom in any moment, etc. This paper adopts MD simulation to study the structure and dynamics characteristics of the amorphousSrTiO3 to make up the scarcity of laboratory research.Owing to poor knowledge of the structure of amorphous SrTiC>3, it is quitedifficult to build up a proper model as an original system to the simulation. Currently researches mostly adapt method of quenching a liquid system to obtain an amorphous state in simulation. In this paper, we will follow this method to obtain amorphous SrTiO3.Under adiabatic approximation, all forces of atoms interacted each other are contributed from the potential. The movements of atoms obey the Hamilton's equations of motion, which can be simplified as the famous Newtown's equation of motion. MD simulation will result in series of trajectories of the simulated system. With the help of statistic physics based analyzing method, a series of instantaneous and interval characteristics such as structure characteristics, dynamics characteristics, etc., can be acquired. From the simulations of various processes of the conditions (temperature, pressure etc.), the effects of conditions can be better understood, which can be used to direct the laboratory experiment.In this paper, molecular dynamics method is adapted. The simulating software is MOLDY and the visual software is VMD. The melting and quenching process of SrTiO3 is studied. Through simulation of crystal SrTiO3, the parameters of PIM and the simulation, such as the step size of and the radius of the cutoff can be refined. After the melting and quenching processes of simulations SrTiO3, the amorphous SrTiO3 is obtained, and the characters of structure and kinetic were analyzed. During the simulations, we collected and studied the radial distribution function (RDF), energy and volume's dependence of temperature the configuration of atoms, coordination number, diffusion coefficient, etc. From these information, we concluded that: first of all, the melting point is estimated at 2420K, about 60K higher than that of experimental value;secondly, the amorphous structure has the basic characters of the molten state, for example, the Ti-0 bond length is 1.845 A ,and the bond angle main distributed in 95.5-122.5°;Thirdly, the average coordination number is 4.92, consistent with the experiment value. Finally, the coordination chemistry, about 60% of Ti is surrounded by 5 oxygen atoms. |
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