Study On Synthesis Of Sn And Dy Doped BaTiO₃ And Photoelectric & Thermophysical Properties

BaTiO₃ has a high permittivity and is widely used in various electronic devices.The rapid development of miniaturization in the electronics industry has put forward higher requirements for high permittivity and high stability.Therefore,the influence of synthesis process and Sn and Dy doping on the photoelectric and thermal properties of BaTiO₃ before and after Curie temperature and phase transition has been studied.In this paper,BaTiO₃ was synthesized by sol-gel method,and the influences of drying mode,roasting temperature and roasting rate on BaTiO₃ nano powder were studied,and the influences of roasting temperature on the reflectivity,dielectric constant,ferroelectricity and thermal expansion of BaTiO₃ and BaTi_0.88Sn_0.12O₃ were also studied.Finally,the effects of different doping amounts of Dy and Sn,Dy co-doping on BaTiO₃ were studied.High-purity nanometer BaTiO₃ powders were synthesized by sol-gel method,and the influence of the synthesis process on BaTiO₃ was investigated.The freeze-dried powder has better crystallinity,and the BaTiO₃ powder can be obtained by roasting at 800?.The tetraneous phase BaTiO₃ and BaTi_0.88Sn_0.12O₃,which are calcined at 1280?¹300?and have thermally induced phase change characteristics,have better dielectric properties and smaller phase change volume effect.The Curie point of sn-doped BaTi_0.88Sn_0.12O₃ was reduced by 40?,and the volume change rate of phase change was effectively inhibited.Dy doping of BaTiO₃ has obvious self-compensating behavior,that is,Dy doping can form two different results of substitution of A and B bits.Moreover,Dy doping can introduce more point defects.The influence of Dy doping amount on Curie temperature is characterized by non-monotonic change,which decreases at first and then increases,but the influence degree is small.The dielectric constant also shows the same variation rule,but the dielectric loss is small.When Sn and Dy are co-doped,they are regulated by Sn⁴⁺ions,and Dy³⁺ions only have a-site substitution.And there is a tendency to cluster Dy ions.Under the condition of constant Sn doping,Curie temperature and permittivity both increase first and then decrease with the increase of Dy content.It also has lower dielectric loss and higher frequency stability.With the increase of Dy content,residual polarization intensity and coercive field decrease.The change of resistivity basically presents a positive resistance temperature coefficient,which may be related to the change of Dy³⁺ion from donor to acceptor.The volume change rate of Sn and Dy mixed with Ba(_1-3x/2)Dy_xTi_1-ySn_yO₃ during the phase transition is effectively suppressed.