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We report complex dielectric and Raman spectroscopy measurements in foursamples of $\alpha$- Fe$_2$O$_3$, consisting of crystallites which are eitherhexagonal shaped plates or cuboids. All four samples exhibit the spinreorientation transition from a pure antiferromagnetic (AFM) to aweak-ferromagnetic (WFM) state at the Morin Transition temperature (T$_M$)intrinsic to $\alpha$- Fe$_2$O$_3$. These samples, pressed and sintered inidentical conditions for the dielectric measurements, reveal moderate but clearenhancement in the real part of the dielectric constant ($\epsilon'$) in theWFM region. However, a relaxation-like behavior in the imaginary part of$\epsilon''$ is observed only in nano plates or big cuboids. Further still,this relaxation patten is observed only in lower frequency region, lasting uptoa few kHz and follows Arrhenius law within this limited range. The activationenergy deduced from the fitting is suggestive of polaronic conduction.Temperature dependent Raman spectra reveal anomalies in all major phononicmodes and also in 2Eu mode in the vicinity of the Morin transition. A peak likebehavior in Raman Shifts, in conjuncture with anharmonic fitting reveals thatthe nature of spin phonon coupling is different in pure AFM and WFM regions andit is tied to the mild variations, as observed in the dielectric constantof$\alpha$- Fe$_2$O$_3$ near the T$_M$.

Dielectric and Raman Spectroscopy in Hematite crystallites across the Morin Transition