0000000000400692
AUTHOR
M. Cestelli Guidi
Optical, infrared and electron-microscopy studies of metallic clusters in layered crystals
Abstract An influence of ( Cd i ) n metallic clusters on the optical absorption and phonon spectra of CdI 2 crystals was studied. Metallic clusters of spherical shape were formed during the growth of non-stoichiometric crystals. Radii of clusters are in range from 10 to 500 nm according to scanning electron microscopy (SEM) data. The density of clusters was estimated from fractal dimension calculations. The fractal dimension of ( Cd i ) n clusters has been found to be varied from 1.488 to 1.793. In the framework of Mie theory the spectral and size dependencies of extinction coefficients were calculated. From the experimentally obtained spectra it is evident that the metallic clusters are re…
Influence of diamagnetic impurity on mid‐IR absorption in antiferromagnetic insulator NiO
-1 was studied in polycrystalline Ni c Mg 1-c O solid solutions with c=0.99, 0.98, 0.97, 0.95, 0.90, 0.80, 0.70 and 0.60. The composition and temperature dependences of the absorption suggest that the band has magnetic origin re- lated to simultaneous excitation of two-magnons at the Brillouin-zone boundary and one phonon. -1 in polycrystalline NicMg1-cO solid solutions. Polycrystalline solid solutions NicMg1-cO (c=0.99, 0.98, 0.97, 0.95, 0.90, 0.80, 0.70 and 0.60) were prepared using ceramic technology from the appropriate amounts of aqueous solutions of Mg(NO3)2·6H2O and Ni(NO3)2·6H2O salts, which were mixed and slowly evaporated. The remaining dry 'flakes' were heated up to 500-600 oC to…
Cadmium clusters in CdI2layered crystals: the influence on the optical properties
The influence of overstoichiometric Cd i atoms on the optical properties of cadmium iodide layered crystals has been investigated. The results of optical absorption, luminescence, and luminescence excitation studies of CdI 2 crystals with controlled deviation from stoichiometric composition allow observing correlations between the Cd i concentration and features in absorption and emission spectra up to concentrations of 10 18 cm -3 . At higher concentrations the overstoichiometric cadmium atoms form clusters, which were observed using scanning electron microscopy. The extinction spectra of (CdI i ) n clusters are calculated in the frame of Mie theory and are found to correlate with the opti…
CsPbCl3 nanocrystals dispersed in the Rb0,8Cs0,2Cl matrix studied by far-infrared spectroscopy
Abstract The comparative far-infrared spectroscopy studies of Rb0.8Cs0.2Cl and Rb0.8Cs0.2Cl containing CsPbCl3 nanocrystals between 170 and 320 K are reported. The effect of cesium lead chloride nanocrystals on the phonon modes of the host matrix, particularly manifested in different temperature behavior of LO–TO splitting and the temperature dependence of high frequency dielectric constant, are demonstrated.