Preparation And Optical Properties Of B-Substituted Perovskite BMT High Refractive Index Films

With the development of modern science and technology,especially laser technology and optical communication technology,ordinary optical films have low refractive index and difficult range control,and it is difficult to meet practical applications such as micro-memory,micro-actuator,micro-sensor,etc.,thus preparing a refractive index with high refractive index.Optical film with flexible range of rate has become one of the leading directions in the development of the film industry.The composite perovskite Ba(Mg_1/3Ta_2/3)O₃?abbreviated as BMT?has been a hot spot in the field of optoelectronics due to its high refractive index,low absorption coefficient and excellent high-frequency dielectric properties in the visible range.The cation substitution can change the crystal structure and regulate its optical and electrical properties.In this paper,perovskite BMT was selected as the research object.Perovskite BMT ceramics and B-site cationic Ti⁴⁺,Zr⁴⁺substituted perovskite BMT ceramics and corresponding optical films were prepared.The optical properties of B-site cation substitution on perovskite BMT were investigated.In particular,the influence of refractive index is of great significance for advancing the development of perovskite BMT series crystals in the field of optics.In this paper,the cell structure of BMT(Ba(Mg_1/3Nb_2/3)O₃ for short BMN)and replaced by BMT Nb⁵⁺ions are constructed firstly,and then the structure is optimized,the energy band structure and state corresponding to BMT and BMN are obtained.Density,it is found that the valence band between-5eV and Fermi level is mainly contributed by the d-orbital of O^2-and the d-orbital of Ta⁵⁺ion/Nb⁵⁺ion,and the conduction band is mainly composed of d-orbit and part of Ta⁵⁺ion/Nb⁵⁺ion.The d-orbital of the Ba²⁺ion is contributed by the p-orbital of the O^2-ion.The optical properties of BMT and BMN are calculated and found that the refractive index of the two in the ultraviolet-visible range decreases with increasing wavelength,which is normal dispersion,and the main reason for the change of optical properties is BO₆structural difference and the difference in the cation orbital hybridization at the B site.In this paper,the corresponding perovskite BMT ceramic target and B-site cation-substituted perovskite BMT ceramic target were prepared by solid phase method,and the phase structure of ceramic was determined by XRD technique.The corresponding optics were prepared by PLD technique.The transmittance,absorptivity,refractive index and third-order nonlinear optical properties of perovskite BMT optical films were studied by UV-Vis spectrometer,ellipsometry and Z-scanning respectively.Perovskite BMT optical films were studied.It has high optical transmittance and low light absorption rate;the refractive index of Ti⁴⁺cation-substituted BMT optical film is significantly increased from 381nm to 469nm,and the refractive index of Zr⁴⁺cation-substituted BMT optical film decreases overall,so Ti⁴⁺is utilized.Zr⁴⁺substitution can significantly expand the refractive index of BMT film in the visible range;in addition,the Z-scan results of BMT,Ti-substituted BMT,Zr-substituted BMT film samples are analyzed,and the nonlinear refractive index is-7.49?10^-10 cm²/W?-7.05?10^-10 cm²/W?-6.44?10^-10 cm²/W,it can be seen that the nonlinear refractive index coefficient is less than zero,indicating the perovskite BMT optical film There is a certain self-defocusing phenomenon.