Preparation And Giant Dielectric Properties Of Co-doped TiO₂ Based Ceramics

The rapid development of the electronics industry has put forward higher requirements for the performance of dielectric materials.A high-performance dielectric material is essential for miniaturization and integration of microelectronic devices.In recent years,the excellent dielectric properties of co-doping Ti O₂ ceramics have attracted widespread attention.Exploring new combinations of co-doping elements not only have great influence on further improving the dielectric properties of Ti O₂ ceramics,but also help to reveal the origin of giant dielectric properties.In this paper,（Sb+La）and（Sb+Yb）co-doped Ti O₂ ceramics were prepared by solid-phase method,and SLTO/PVDF composite materials were prepared by cold sintering method.After various experimental characterizations,the analysis and discussions were carried out.The research content is divided into the following points:(Sb_0.5La_0.5)_xTi_1-xO₂（x=0.008,0.01,0.02）（abbreviated as SLTO）ceramics were prepared by solid-phase method.X-ray photoelectron spectroscopy shows that the doping of La³⁺is conducive to the generation of oxygen vacancies,so the defect dipole clusters are formed in the ceramics.Co-doped Ti O₂ceramics have the excellent dielectric properties when x=0.01.（At 1k Hz,the dielectric constant is 6.5866×10⁴,and the dielectric loss is0.0464.）The dielectric performances for(Sb_0.5La_0.5)_0.01Ti_0.99O₂ keep good stability in the temperature range of room temperature-160^oC and the frequency range of 10² Hz～10⁶Hz.The E-J curve shows that SLTO ceramics are sensitive to pressure.The result of impedance spectroscopy shows that the IBLC effect and electrode effect all contribute to the excellent dielectric properties of SLTO co-doped ceramics.The composite material of SLTO（x=0.01）and PVDF was prepared by cold sintering method.The micro-morphology and dielectric properties of the ceramic/polymer composites were studied.As the increasing of content for creamics,the diffraction peak of the polymer is suppressed by the strong peak of the ceramic.The result of SEM and EDS shows that all composite materials have dense structure,and PVDF is evenly wrapped around ceramic particles.The best dielectric properties are obtained when(Sb_0.5La_0.5)_0.01Ti_0.99O₂ is compounded with PVDF in equal proportions,the dielectric constant is 158.6 and the dielectric loss is 0.19.The non-equimolar doped(Sb_xYb_1-x)_0.04Ti_0.96O₂（x=0,0.4,0.5,0.6,1）ceramics（abbreviated as SYTO）prepared by traditional solid-phase method shows excellent dielectric properties.Only doping with Sb can increase the dielectric constant of the Ti O₂ceramic,while with high dielectric loss;only doping Yb can improve the temperature stability of dielectric performance for Ti O₂ ceramic.The co-doped ceramics show high dielectric constant and low dielectric loss.Doping with more Yb,the grains of samples are small,the amount of interface is increased,interfacial effects significantly effect the dielectric performance;When the incorporation of Sb increases,it is beneficial to form the defective clusters dipole,reducing the dielectric loss of the samples.When the doping ratio is Sb:Yb=1:1,the dielectric properties of SYTO ceramics show the best performance（At1k Hz,ε’is 6.4527×10⁴,and the tanδis 0.016）.Dielectric properties maintain good stability in broad range of 10² Hz～10⁶Hz and room temperature-200^oC.Combined all datas,it shows that the formation of defect dipole clusters and the interfacial polarization at the grain boundary are all helpful to the high dielectric constant and low dielectric constant for SYTO samples.