| With the advent of the 5G information technology era,in order to meet the high-level development of information technology,the market's demand for high-end electronic components has further increased.Capacitors are basic electronic components,in which multilayer ceramic capacitors(MLCC)occupy most of the capacitor market.In order to meet market requirements of capacitors for miniaturization and integration,it is necessary to further improve the dielectric constant of dielectric materials and reduce their dielectric loss.TiO2 material has been widely concerned by people for its satisfactory dielectric properties and stability of temperature and frequency since it was discovered.This material has a certain application prospect,but it is difficult to be applied in practice because of its large dielectric loss.It is known that if there are too many free electrons in the material,the dielectric properties of the material will deteriorate,thus increasing the dielectric loss of the material.Therefore,the dielectric loss can be effectively reduced by limiting the movement of free electrons in the material.By designing and regulating the electronegativity of doping ions,the electrons are bound more tightly to achieve the purpose of low dielectric loss.In this paper,we further improve the dielectric properties of TiO2-based materials by adjusting the electronegativity of doping ions and clarify its polarization mechanism.Design and prepare three kinds of doping ions with different electronegativity(Ag2/5Mo3/5)xTi1-xO2(AMTO),(Ag2/5W3/5),Ti1-xO2(AWTO)and(Li2/5W3/5)xTi1-xO2(LWTO)material.The main research conclusions are as follows:(1)By exploring the influence of different sintering temperatures and holding time on the dielectric properties and microstructure of(Ag2/5Mo3/5)xTi1-xO2 ceramic materials,the optimal preparation conditions were determined as follows:the pre-firing temperature of 1100?,the sintering temperature of 1450?,and holding of 15 h in the atmosphere of circulating nitrogen.The sample of AMTO ceramic with x=1.25%obtained good dielectric properties:when the test frequency is 1 kHz,the dielectric constant reaches 2.0×104,the dielectric loss is reduced to 0.045,and the temperature stability meets the requirements of Z9P(10?200?,??T/?25? ?±10%)capacitor.(2)Keep the acceptor ion unchanged,use W6+which has lager electronegativity as the donor ion,and design(Ag2/5W3/5)xTi1-xO2 ceramic material.The optimum preparation conditions for AWTO ceramic materials are:pre-sintering at 1000?1100?for 3 h,and sintering at 1450?1480? for 10 h in a circulating nitrogen atmosphere.The results show that AWTO ceramics with x=1.25%have the most excellent dielectric properties:at 1 kHz,the dielectric constant is as high as 2.3×104,and the dielectric loss is as low as 0.031;at 10 kHz,the dielectric constant is as high as 2.2×104 The dielectric loss is as low as 0.025.At 1 kHz,AWTO1.25 ceramic samples can meet the temperature range requirements of X9P(-55?200 ?,??T/?25? ?±10%)capacitors.Through AC impedance analysis and XPS analysis to determine the source of the semiconductivity of the crystal grains,it is further confirmed that the generation of the giant dielectric properties is due to the IBLC effect.(3)Choose Li+with less electronegativity as the acceptor ion doping,keep the donor ion as W6+,and design(Li2/5W3/5)xTi1-xO2 ceramic material.Using buried sintering method,when the temperature was kept at 1400? for 15 h in the circulating nitrogen atmosphere,the LWTO ceramic sample with x=0.5%obtained excellent dielectric properties:when the test frequency is 10 kHz,the dielectric constant is 1.4×104,the dielectric loss is 0.035 and meets the operating temperature range requirements of X9P(-55?200 ?,??T/?25?)capacitors.(4)In three material systems ?Ag>?Li,?W>?Mo,the corresponding AWTO ceramic materials have better performance than AMTO ceramic materials,and the performance of AWTO ceramic materials is better than LWTO ceramic materials.The influence of electronegativity on the dielectric loss of materials is revealed,which indicates that doped ions with large electronegativity can effectively reduce the dielectric loss of materials. |
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