Morphology and luminescence of nanocrystalline Nb₂O₅ doped with Eu³⁺

The synthesis of nanocrystalline Nb2O5:Eu3+ has been achieved by using a Pechini procedure. The obtained materials are single-phase niobia with the orthorhombic structure, average crystallite size around 25nm and average lattice strain of about 0.002. TEM images show that the particles are rectangular and reasonably isolated. The luminescence of the Eu3+ ions in the niobia lattice is efficient and affected by a strong inhomogeneous broadening, due to an important disorder around the lanthanide ions

Synthesis, Structural investigation and luminescence spectroscopy of nanocrystalline Gd3Ga5O12 Doped with lanthanide ions

Gadolinium gallium garnet (GGG) nanocrystalline powder doped with. lanthanide ions (Eu3+ and Er3+) have been obtained using two different methods (coprecipitation and Pechini). The X-ray diffraction results show that single phase cubic GGG nanopowders have been obtained for both preparation methods. The samples prepared by the two procedures show different morphologies, as revealed by scanning electron microscopy images. The Er3+-doped nanopowders obtained with the coprecipitation method show strong luminescence upon 488.0 nm excitation. The emission spectrum is similar to the one of the single crystal and of nanopowders of the same composition prepared by a combustion synthesis. The Er3+-doped GGG nanopowders obtained by the coprecipitation method show efficient upconversion in the green region (around 550 nm) upon excitation in the near IR at a wavelength of 800 nm

Morphology and Luminescence of Nanocrystalline Nb2O5 Doped with Eu3+

The synthesis of nanocrystalline Nb2O5:Eu3+ has been achieved by using a Pechini procedure. The obtained materials are single-phase niobia with the orthorhombic structure, average crystallite size around 25 nm and average lattice strain of about 0.002. TEM images show that the particles are rectangular and reasonably isolated. The luminescence of the Eu3+ ions in the niobia lattice is efficient and affected by a strong inhomogeneous broadening, due to an important disorder around the lanthanide ions

Synthesis, structural investigation and luminescence spectroscopy of nanocrystalline Gd₃Ga₅O₁₂ doped with lanthanide ions

Gadolinium gallium garnet (GGG) nanocrystalline powder doped with lanthanide ions (Eu3+ and Er3+) have been obtained using two different methods (coprecipitation and Pechini). The X-ray diffraction results show that single phase cubic GGG nanopowders have been obtained for both preparation methods. The samples prepared by the two procedures show different morphologies, as revealed by scanning electron microscopy images. The Er3+-doped nanopowders obtained with the coprecipitation method show strong luminescence upon 488.0 nm excitation. The emission spectrum is similar to the one of the single crystal and of nanopowders of the same composition prepared by a combustion synthesis. The Er3+-doped GGG nanopowders obtained by the coprecipitation method show efficient upconversion in the green region (around 550 nm) upon excitation in the near IR at a wavelength of 800 nm

Spontaneous Self-Assembly of an Unsymmetric Trinuclear Triangular Copper(II) Pyrazolate Complex, [Cu3(\u3bc3-OH)(\u3bc-pz)3(MeCOO)2(Hpz)] (Hpz = Pyrazole). Synthesis, Experimental and Theoretical Characterization, Reactivity, and Catalytic Activity

The almost quantitative formation of the triangular trinuclear copper derivative [Cu3(\u3bc3-OH)(\u3bc-pz)3(MeCOO)2(Hpz)] (1) (Hpz = pyrazole), has been simply achieved by adding Hpz to an ethanol solution of Cu(MeCOO)2\ub7H2O. An X-ray molecular structure determination shows that 1 is completely unsymmetric and that trinuclear units result assembled in an extended bidimensional network formed through acetate bridges and hydrogen bonds. EPR and magnetic measurements are consistent with the presence of a single unpaired electron. Theoretical density functional calculations carried out for S = 1/2 provide a thorough description of the electronic structure of 1, allowing a detailed assignment of its UV 12vis absorption spectrum. Compound 1 reacts with MeONa, yielding [Cu3(\u3bc3-OH)(\u3bc-pz)3(MeCOO)(MeO)(Hpz)] (2) and [Cu3(\u3bc3-OH)(\u3bc-pz)3(MeO)2(Hpz)] (3) through the substitution of one and two acetate ions, respectively, with MeO- ion(s). The spontaneous self-assembly of the triangular trinuclear Cu3 moiety seems to occur only with pyrazole as can be inferred by the results obtained in the reactions of copper(II) acetate with some substituted pyrazoles leading to the formation of mononuclear [Cu(MeCOO)2(L)2] (4 128) and dinuclear [Cu(MeCOO)2(L)]2 (9 1211) (L = substituted pyrazole) compounds. Also the presence of acetate ions seems to play a leading role in determining the formation of the trinuclear triangular arrangement, as indicated by the formation of a mononuclear derivative, [Cu(CF3COO)2(Hpz)]2 (compound 12), in the reaction of copper(II) trifluoroacetate with pyrazole. Compounds 1 123, as well as some other mono- and dinuclear copper(II)-substituted pyrazole complexes, have been tested as catalyst precursors in cyclopropanation reaction, observing the formation of products in a syn:anti ratio opposite that normally reported