Effect of seawater and salt-rich air on dielectric properties of La and Mg doped barium titanate ceramics
La3+and Mg2+were doped into barium titanate by grinding and annealing process,and three groups of samples with doping ratio of 2％,3％and 4％(molar fraction)were prepared.The samples were placed in seawater and salt-rich air environment for 0,24,48 and 72 hours.By means of impedance analyzer,XRD,SEM and EDS,the effects of seawater and salt-rich air on dielectric properties of doped barium titanate ceramics were studied.The results show that the increment of permittivity of barium titanate doped with La3+at low frequen-cy(102-103 Hz)is lower than that of pure barium titanate,while the increment of permittivity of Mg2+at low frequency is higher than that of pure barium titanate during 72 h in seawater.Through SEM,it can be clearly seen that the corrosion degree is lightest when the molar ratio of La3+is 4％,which is due to its high sintering density,and the porosity of Mg2 doped barium titanate ceramics increases and the corrosion intensifies.In ad-dition,no matter La3+or Mg2+doping,the dielectric loss is not protected in the salt-rich air for 72 h,because the introduction of La and Mg makes barium titanate produce obvious pores in the humid environment,and the salt crystallizes in the internal air,which is rich in salt and easily ionized,resulting in an increase in dielectric loss.By XRD analysis of the treated samples,there is no obvious peak shift and no miscellaneous peaks.The presence of other components on the sample surface can be clearly seen by EDS.
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