BBAuthors: Salama, A.H.; Advisor: -; Participants: Youssef, A.M.; Rammah, Y.S.; El-Khatib, M. (2019)
The ac conductivity was further studied for undoped YBCO and doped YBCO with 0.1 wt.% of nano-metal oxide of Cr2O3, Co3O4, and Mn3O4 samples. For all the studied samples, we found σac is typically specified to the hopping conduction and ac conductivity has a power law behavior in terms of frequency (ω). In general, there are two frequency-dependent regions for all the studied ceramic samples; in the low-frequency region, σac is independent of frequency whereas in the high-frequency region, dispersion occurs. The change in microwave conductivity of the studied samples with frequency (1–5 MHz) is shown in Fig. 5. It is observed that for all samples, the conductivity increases with tempe... 
