Study On The Dielectric Properties Of Nd-doped SrTiO₃-based Ceramics

Multilayer ceramic capacitor (MLCC) has been widely used in mobile phones, computers digital camera cars other fields has many characteristics such as small equivalent series resistor (ESR), big rated ripple current, varieties complete specifications, small size, non-polarity and small leakage current etc. In recent years, mobile electronic equipment miniaturization makes multilayer ceramic capacitor gradually develop to low cost, miniaturization, large capacity. The materials of high dielectric constant can effectively improve the MLCC unit volume, increase the capacity of hematocrit value, reduce capacitor product volume and adapt to above trend. Currently the MLCC material of high dielectric constant generally is BaTiO3, many scholars studied researched the material and improved its performance, but the dielectric constant is commonly 5000, it is difficult to be further improved and development. It is very important to develop new materials of high dielectric constant and stable temperature variation of dielectric constant.In this study, the microcosmic structure and dielectric properties of NdxSr1-xTiO3 (x=0.08～0.14) system were studied. It was found that the material with rare earth Nd still maintains cubic phase structure, crystal cell parameters is reduced and rare earth Nd can suppresse the grain growth. The dielectric performance of the materials vary significantly. With the amount of adulteration increasing, the dielectric constant shows the trend of first increases and then decreases and has a "giant permittivity effect", the dielectric loss has increased. In x=0.12, the dielectric constant is 15900 which is the maximum. The material has relaxation characteristics with the temperature chang, it has electrical heterogeneity structure, this system has giant dielectric constant due to the effect of the interface relaxation.In order to further improve the performance of NST system and meet the requirements, MnO2, ZrO2, and SiO2 were chosen respectively to dope in Sr0.88 Nd0.12 TiO3 system and the doping quantity is 0.1～1.0 wt%. The performance is excellent when doping respectively 0.1 wt% Mn and Si:when doped MnO2, the dielectric constant and the temperature variation of dielectric constant performance all are optimized,withε=35700 and the temperature range ofΔC/C≤±15% is -55～+ 200℃;when doped Si02,the dielectric loss and the temperature variation of dielectric constant performance all are improved withε=6650,tanε=0.079,the temperature range ofΔC/C≤±15％is -55～+100℃.