Study Of Ceramic Materials With X8R And Capacity Measurement System Design

Multilayer ceramic capacitors （MLCC） which have thermal stability and highpermittivity are important fundamental components used in electronic andinformation technology.Barium titanate （BaTiO₃, BT）-based ceramic materials with high permittivityand thermal stability were mainly studied in this paper. Pure BaTiO₃-based ceramicmaterials could not match the requirement to produce MLCC with high permittivityand thermal stability. Doping in BT-based ceramic materials were studied to improvethe poperties. Firstly, Nb2O5-Co2O₃doped BaTiO₃-based ceramic materials werediscussed, then BaTiO₃-based ceramic materials doped with other oxides （CeO₂,Nd2O₃,MnCO₃） were found to be improved in sintering temperature, curie peak andpermittivity. Finally, the effect of Bi₂Sn₂O₇doped in BaTiO₃-based ceramic materialson permittivity and thermal stability was studied. The addition of calcination timeswas also studied. The samples were characterized by X-ray diffraction （XRD） andscanning electron microscopy （SEM）.BaTiO₃-based ceramic materials doped with oxides （Nb2O5, Co2O₃, CeO₂, Nd2O₃,MnCO₃） were greatly improved in permittivity and thermal stability. Even so, thethermal stability did not meet the X8R specifications. The effect of BaTiO₃-basedceramic materials doped with Bi₂Sn₂O₇, which was synthesized by Bi2O₃and SnO₂,were also studied in this paper. BaTiO₃-based ceramic materials which were dopedwith2mol%Bi₂Sn₂O₇and sintered at1200oC had the highest permittivity andthermal stability. With the doping amount of Bi₂Sn₂O₇increased, the permittivity ofBaTiO₃-based ceramic materials increased at first and then decreased, the TCC atcurie temperature （Tc） was more than15%at first and then less than-15%. In addition,with the sintering times increased, the curie peak moved toward the high temperatureregion.The developed Agilent-based Capacitor Measurement （ACM） system greatly increasedthe testing efficiency. The system includes controlling terminal, hardware controllingcircuit module and temperature sensor, etc. Altium Designer10was used to designPCB for hardware module.