Moscow Engineering Physics InstituteUsp. Fiz. Nauk 133, 653-692 (April 1981) This review considers the present status of theoretical and experimental investigations of fine metallic particles (FMP) with characteristic dimension from 100 to 1 nm. An analysis is made of the influence of the size of FMP on the structure, on the phonon spectra, the heat capacity, the Debye temperature, the behavior of the FMP in an electromagnetic field, the relaxation of the electronic spins, the magnetic susceptibility, and the optical properties. Changes in the structure and in the phonon spectrum are due chiefly to disintegration of the surface layers of atoms and to the large curvature of the surface of the FMP. The electronic states of FMP are treated with allowance for the pronounced discreteness of the levels. A comparison is made of theoretical and experimental results on the effect of the parity of the number of electrons in the particles on the paramagnetic susceptibility and on the Knight shift. Relaxation of electron spins in FMP of alkali metals is discussed with allowance for the effect of the surface and of impurities, and also of a possible contribution from the pronounced discreteness of phonon and electron states. Investigations of optical properties and of plasma oscillations indicate an important role of surface states in relation to electronic transitions in FMP.

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We have studied the effect of the size of gadolinium particles on their structure and magnetic properties. Particle sizes varied within the range from 1000 to 200 g. X-ray diffraction investigations showed that the structure of fine gadolinium particles can be presented a s a three-phase mixture: a hexagonal close-packed ( h . c . p . ) phase, fully corresponding to the lattice of the gadolinium bulk sample, and two face centered cubic (f. c . c. ) phases with the parameters a = ( 5 . 3 2 1 and a = 5 . 3 9 2 % (11). With the decrease of particle size the h . c . p . phase gradually disappears, and in particles with d = 200 8 it i s completely absent. The f . c . c .phase at first appears in the form of structure I , which is later replaced by structure 11. The weight fraction of phase I1 in particles with d = 200 8 is close to 80%. . 8 ) a (I)

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