  We report high temperature synchrotron X-ray diffraction (SXRD), dc
magnetization and current-voltage (I-V) characteristics for the samples of
Co$_{2.75}$Fe$_{0.25}$O$_4$ ferrite. The material was prepared by chemical
reaction of the Fe and Co nitrate solutions at pH = 11 and subsequent annealing
at temperatures 200 0C, 500 0C and 900 0C. The measurements were performed by
cycling the temperature from 300 K to high temperature (warming mode) and
return back to 300 K (cooling mode). The SXRD patterns indicated a fine
bi-phased cubic spinel structure in the highly Co rich spinel oxide.
Magnetization curves showed intrinsic ferrimagnetic features and defect induced
additional ferromagnetic phase at higher temperatures. Electrical conductivity
showed thermal hysteresis loop between warming and cooling modes of temperature
variation. The samples exhibited new information on the irreversibility
phenomena of lattice structure, magnetization and electrical conductivity on
cycling the measurement temperatures.
