Luminescence of Ce³⁺ in Y₂SiO₅ Nanocrystals:  Role of Crystal Structure and Crystal Size

Abstract

Here, we report the role of crystal structure and crystal size on the photoluminescence properties of Ce3+ ions in Y2SiO5 nanocrystals. The emission at 430 nm (5d1 --> 4f1) and lifetime of the excited state of Ce3+ ion doped Y2SiO5 nanocrystals are found to be sensitive to the crystal structure, crystal size, and dopant concentration. It is found that the overall lifetime tau of 0.5 mol % Ce doped Y2SiO5 nanocrystals are 8.78 and 3.45 ns for 1000 and 1100 degrees C heat-treated samples with the same crystal structure (X1-Y2SiO5 phase), respectively. However, a significant increase in the overall lifetime (35.21 ns) is observed for the 1300 degrees C annealed 0.5 mol % Ce doped Y2SiO5 sample having a different crystal structure (X2-Y2SiO5 phase). We found that the decay kinetic is biexponential. It is explained that the fast component arises due to sequential hole-electron capture on the luminescent ions and the slow component arises from isolated ions. Our analysis suggests that modifications of radiative and nonraditive relaxation mechanisms are due to local symmetry structure of the host lattice and crystal size, respectively.

Impacts of core–shell structures on properties of lanthanide-based nanocrystals: crystal phase, lattice strain, downconversion, upconversion and energy transfer

“…It is evident that the spontaneous emission probability of optical transition probabilities (luminescence lifetime) from rare-earth activated nanocrystals can be significantly modified by changing the particle size, shape and surrounding medium by modifications of its (i) photon emission probability and/or (ii) phonon emission probability. [12][13][14][15] This can be explained by the lowering of site symmetry of the ion in neighbouring position to another ions. As explained in detail by the Judd-Ofelt theory, the lowering of symmetry allows an intermixing of the f states of the rare-earth ions with a higher state configuration such as 5d, and allows to some extent a decrease of the forbidden nature of the transition.…”

Influence of sodium dodecyl sulfonate (SDS) on the hydrothermal synthesis of YVO4:Eu3+ crystals in a wide pH range

“…Fig. 6 shows PL excitation spectra of the Y 0.95 Eu 0.05 VO 4 crystals synthesized at 180 • C for 24 h with different pH values (pH 1,4,7,14) under the emission of 619 nm. The excitation spectrum of the YVO 4 :Eu 3+ nanopowders consists of a broad band ranging from 200 to 350 nm with a maximum peak at about 308 nm and a shoulder at 277 nm, which is due to the absorption of VO 4 3− clusters.…”

“…The spontaneous emission probability of optical transitions from rare-earth ion-doped nanoparticles may vary with particle size, shape, and surrounding medium [7][8][9][10][11]. Since the electronic f-f transitions of the rare-earth ions are localized in the atomic orbital of the ions, no size-dependent quantization effect from the confinement of delocalized electrons can be found.…”

“…To the best of our knowledge, there have been few reports on the morphology-controllable synthesis of YVO 4 :Eu 3+ powders by a SDS-assisted hydrothermal process in a wide pH range. Consequently, here we report a simple SDSassisted hydrothermal approach to prepare nano-and micro-scaled YVO 4 :Eu 3+ crystals with various morphologies in a wide pH range (pH [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The phase structure, composition, morphology, and optical properties of the as-synthesized samples are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence spectroscopy (PL), respectively.…”

Emission enhancement of Eu(III) and/or Tb(III) ions entrapped in silica xerogels with ZnO nanoparticles by energy transfer

“…From a fundamental point of view, the physical understanding of the luminescence properties of Ln(II) ions in nanocrystals and the way it varies with size, crystal phase, coordination environment and concentration is very important. It is presently recognized that efficiency depends on the particle size, the size symmetry and concentration of Ln(III) as active ions [17][18][19][20].…”