Molecular Dynamics Study Of The Effects Of Compressive Strain On Anti-radiation In BaTiO₃ Ferroelectric

Ferroelectric materials have ferroelectric, dielectric, piezoelectric, thermoelectric, electron/phonon inducing light emitting effects etc, and can be processed to functional device such as ferroelectric memory, detector and sensor, which are wildly used in microelectronics, optoelectronic and aerospace field. Recently, higher requirements on stability and reliability are demanded with the rapid development of aerospace and nuclear technology. Ferroelectric materials and device have attracted considerable attention due to their good radiation stability which are suitable for the application of the above mentioned fields. However, under high energy particles irradiation, ferroelectric materials and device will degrade or even failure when suffering radiation damage that threatens reliability and stability of their application. Various properties of ferroelectric materials can be modulated by strain engineering, such as compressive strain will enhance polarization, phase transition temperature and defects formation energy. However, strain engineering was not implemented into the research of ferroelectric material radiation effects yet, and there lacks experimental examination and theoretical verification. Therefore, in this paper, the compressive strain effect on the anti-radiation of BaTiO3 ferroelectric was investigated via molecular dynamic with shell model.Firstly, the effect of compressive strain on radiation induced displacement of BaTiO3 ferroelectric was studied by molecular dynamic with shell model. O atom was chose as the primary knock-on atom(PKA) with energy of 1 keV and [001] direction. It was found that the compressive strain will suppress the formation of defects efficiently by statistic the numbers of defects during radiation with various strains. In case of 0 and 2% compressive strain, we have compared local damage at different simulation time; migration distance of defects after equilibration and PKA drift distance under bias potential were also calculated. Radiation damage area, defect atom dislocation distance and PAK drift distance under bias were reduced under compressive strain. The existence of compressive strain will suppress the lattice radiation damage and defects migration. Hence, BaTiO3 radiation damage can be modulated by introducing compressive strain.Secondly, we examined the influence of compressive strain on BaTiO3 property evolution under radiation process. The polarization of single BaTiO3 domain before and after radiation with various compressive strains were calculated respectively. Polarization almost increases linearly with increasing of compressive strain, the degradation of polarization by radiation was suppressed and thus stability was improved with the existence of compressive strain. Hysteresis loop with 0 and 0.4% compressive strain before and after radiation were calculated respectively. It was noted that the remnant polarization, coercive field and the maximum polarization under 0.4% compressive strain were enhanced; the maximum polarization after radiation and the polarization stability were improved as well. Thus, we conclude that the existence of compressive strain is beneficial to BaTiO3 radiation stability for both the magnitude and stability of polarization.