Comparative Structural and Optical Properties of Different Ceria Nanoparticles

Herein a comparative study of five nanocrystalline cerium oxides (CeO2-delta) synthesised by different methods and calcined at 500 degrees C is reported. XRPD analysis showed that stoichiometry parameter delta, crystallite size/strain and lattice constant were only slightly affected by the method utilized. All ceria nanoparticles are nearly spherical in shape with faceted morphology, free of defects and with a relatively uniform size distribution. The average microstrain was found to be approximately 10 times higher than that of bulk counterpart. The absorption edge of nanocrystalline materials was shifted towards a higher wavelengths (red shift) in comparison with bulk counterpart, and band gap values were in the range 2.7-3.24 eV (3.33 eV for bulk counterpart)

Effects of Eu3+ Concentration on Structural, Optical and Vibrational Properties of Multifunctional Ce1-X,EuXO2-delta Nanoparticles Synthesized by Thermolysis of 2,4-Pentanedione Complexes

The 5-10 nnn Ce1-XEuXO2-delta (0 lt = x lt = 0.30) nanoparticles with fluorite structure were synthesized by thermal decomposition of Eu- and Ce-2,4-pentanedione complexes mixtures. X-ray line broadening analysis of mixed samples Ce1-XEuXO2-delta (0.05 lt = x lt = 0.30) showed that the crystallite size was lower and root mean square strain higher than in pure ceria. However, within mixed samples Ce1-XEuXO2-delta (0.05 lt = x lt = 0.30) crystallite size and root mean square strain were independent of Eu3+ concentration. Raman spectroscopy results indicated that europium ions yield disorder by breaking the phonon propagation and therefore making the non-centre Brillouin zone modes Raman active. The absorption bands in the spectra of mixed oxides were blue-shifted in comparison to pure CeO2-delta nanopowder. The samples show red emission typical for Eu ions. The biggest photoluminescent intensity was observed for the highest Eu3+ concentration (x = 0.30) and further enhanced with the increase in crystallinity

Effects of Eu3+ Concentration on Structural, Optical and Vibrational Properties of Multifunctional Ce1-X,EuXO2-delta Nanoparticles Synthesized by Thermolysis of 2,4-Pentanedione Complexes

The 5-10 nnn Ce1-XEuXO2-delta (0 lt = x lt = 0.30) nanoparticles with fluorite structure were synthesized by thermal decomposition of Eu- and Ce-2,4-pentanedione complexes mixtures. X-ray line broadening analysis of mixed samples Ce1-XEuXO2-delta (0.05 lt = x lt = 0.30) showed that the crystallite size was lower and root mean square strain higher than in pure ceria. However, within mixed samples Ce1-XEuXO2-delta (0.05 lt = x lt = 0.30) crystallite size and root mean square strain were independent of Eu3+ concentration. Raman spectroscopy results indicated that europium ions yield disorder by breaking the phonon propagation and therefore making the non-centre Brillouin zone modes Raman active. The absorption bands in the spectra of mixed oxides were blue-shifted in comparison to pure CeO2-delta nanopowder. The samples show red emission typical for Eu ions. The biggest photoluminescent intensity was observed for the highest Eu3+ concentration (x = 0.30) and further enhanced with the increase in crystallinity

Caričin Grad I. Les basiliques B et J de Caričin Grad. Quatre objets remarquables de Caričin Grad. Le trésor de Hajdučka Vodenica

Duval Noël, Popović Vladislav, Jeremič Miroslav et al. Caričin Grad I. Les basiliques B et J de Caričin Grad. Quatre objets remarquables de Caričin Grad. Le trésor de Hajdučka Vodenica. Édité par Noël Duval et Vladislav Popović. Préface de Charles Pietri et Georges Vallet. Rome : École Française de Rome, 1984. 234 p. (Publications de l'École française de Rome, 75-1