Dielectric properties of polymer-derived ceramic reinforced with boron nitride nanotubes

The electrical and dielectric properties of boron nitride nanotubes (BNNTs) reinforced ceramic composites using the polymer-derived ceramic (PDC) processing route were investigated in this work. The electrical resistivity of the pristine PDC increases from 10(6)to 10(8) omega m after the addition of BNNTs. When the BNNT loading was increased to 5 wt%, the average real relative permittivity of the PDC decreased from 2.94 to 2.80, while the quality factor (Q) of the PDC increased from 134.40 to 176.77. The BNNTs can increase theQfactor of the PDC due to the reduction in the porosity cause by the introduction of the BNNTs. Further increasing the BNNT content decreases the real relative permittivity of the nanocomposites and increases theQfactor at high frequency. The average real relative permittivity decreases to 2.29, while the averageQfactor increases to 208.60 when the BNNT content is increased to 30 wt%. The dielectric loss after the addition of high fraction of BNNTs can be explained by the Lorentz resonance relaxation process. Results of this work showed that PDC-BNNT nanocomposites are satisfactory electromagnetic transparent materials when the BNNT fraction is less than 10 wt%.