I have synthesized some doped metal oxides. dopant has enhanced the dielectric constant and AC conductivity, but at the same time loss tan is also high in doped sample compared with the pristine metal oxide. Is it possible to have high loss tan while having high dielectric constant and high AC conductivity. What could be the possible reason of high loss tan, how it can be justfied in light of reported literature.
Thanks
Dear Ayesha Javaid,
Take a look at the following data:
https:/www.researchgate.net/post/What-is-the-reason-behind-high-loss-modulus-in-a-dielectric-measurement
https://www.researchgate.net/post/What-is-the-relation-between-dielectric-constant-and-conductivity
Dear Ayesha Javaid ,
yes, it is possible to have high loss tan while having high dielectric constant and high AC conductivity, due to (high?), resting humidity[1] (during synthesis).
A hint: Try to dry, and remeasure.
1. Magnesium Oxide Nanoparticles: Dielectric Properties, Surface Functionalization and Improvement of Epoxy-Based Composites Insulating Properties
https://www.mdpi.com/2079-4991/8/6/381/pdf
Dear Ayesha Javaid و
In your material you have ohmic losses because of the electrical conduction in the material. The conductivity increases by doping.
If you measure the capacitance and the resistance in parallel then you have
the admittance of the capacitor= jwC + G
where G is the conductance, w is the frequency and C is the capacitance
Then G = sigma A/d with sigma is the conductivity , A is the area of the capacitor and D is its thickness. C= epsilon A/d where epsilon is the dielectric constant of the oxide material which is more or less independent of the doping.
The loss tangent is
tan delta= G/ wC= sigma/ w epsilon,
If tan delta increases, while both sigma and epsilon increase then it is clear that sigma increases with the doping more than the increase in epsilon.
It is know that the doping slightly affects the dielectric consent while it it increase appreciably the conductivity.
My advice to you is to plot sigma with the doping concentration and do the same for the epsilon. If the increase of sigma is greater than that of epsilon this will be a verification for the model developed here.
Best wishes
Hi Ayesha Javaid, thanks for asking this question. It could be the polarization happened in the sample. May I know you are measuring at which frequency region?
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