I have measured frequency dependent dielectric properties in orthoferrites at different temperature from RT - 300 C. The real and imaginary part of dielectric constant was determined using the reactance (Z'') and resistance (Z'). At higher temperature such as 200 C, the Z'' values are found to be very low such as 0.25 Ohm at 100 Hz and maximum is found to be 150- 200 Ohm, although the Z' values are in the order of kOhm. So, the calculated value of imaginary part of dielectric constant is very high (eg. 2E6 at 100 Hz and 1000 at 1MHz). The maximum loss tangent was found to be in the order of 3000 at lower frequency. Is it possible to have such high value of loss tangent? If yes, what could be the possible reason? Is it due to M-W effect?
Dear Mr Bipul Deka
Getting such high values for the loss tangent is not familiar. The Following Handbook entiteled: "Ceramic Interconnect Technology Handbook, Editors Fred D. Barlow, III, Aicha Elshabini - 2007 - pp(456)) may help you. The book gives details about capacitanc and loss tanget and the effect of temperature and frequecy on the materials. The following Application Guidelines for Aluminum Electrolytic Capacitors PDF file may be useful for your case. Find in the attachment
Hi Bipul,
Experimentally you can obtain such high values of loss tangent from a material which is a very bad insulator, with resistive contributions that are predominant with respect to the dielectric ones. You can try to perfrom the dielectric characterization ati higher frequencies. In this way you can reduce the resistive contribution.
There may be lots of space charges in your sample, which is sensitive to the external electric field at high temperature. The motions of space charges under E field result in high leakage current, which contribute a lot to the dielectric loss.
