Hello dear,
Normally, the relaxation peak of the imaginary part of impedance shifts to a higher frequency with increasing temperature, but we face to face a case. Firstly, the relaxation peak of the imaginary part of the impedance shifted to a higher frequency region with increasing temperature between 300-350K, then it shifted to a lower frequency region with increasing temperature between 350-400K. We have taken measurements again and again, but we obtained the same result. When I examined the literature, I can not find the same result. Why could the case happen?
Thank you a lot.