INFRARED SPECTRUM STUDY ON OPTICAL SURFACE PHONON MODES OF SMALL α-Fe2O3 ELLIPSOIDAL PARTICLES

Small haematite particles with well-defined elliposidal and spherical shapes are prepared by improved forced hydrolysis of ferric chlorid. The measurements of mid- and far-infrared transmission spectra of the small particles provide obvious experimental evidence of the influence of the shapes of small particles on the absorption of surface phonon mode. The theory proposed by Ruppin et al. is applied to small multi-atomic anisotropic α-Fe2O3 particles, and the experimental results are discussed.