Characterization of Nanoporous Lanthanide-Doped Gadolinium Gallium Garnet Powders Obtained by Propellant Synthesis

Abstract

Abstract. In the present work we study the nanocrystalline powders of lanthanide-doped Gd 3 Ga 5 O 12 (GGG, gadolinium gallium garnet) prepared using propellant synthesis. A series of GGG samples containing a number of different trivalent lanthanide ions (Tm, Er, Ho, Eu, Sm, Nd, and Pr) in different quantities (1%, 5%, 10%) were produced. Samples were characterized by X-ray diffraction (pre-and post calcination) for phase identification and line-broadening analysis, and by electron microscopy (SEM and TEM) for morphological and nanostructural investigation. Thermal behavior of the powder was investigated by thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). The samples have a polycrystalline porous structure. Elemental microanalysis made by energy dispersive X-ray spectroscopy (EDX) detector attached to TEM and XRD unit-cell determinations confirmed that the lanthanides ions entered the structure of GGG. Crystallites have a high degree of disorder.

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

“…3). The spectrum is closely similar to that found for a GGG:Er 3+ nanocrystalline sample of the same composition prepared by a combustion synthesis [10]. The room temperature decay curve (not shown) of the thermalised 2 H 11/2 , 4 S 3/2 levels shows a non-exponential behaviour.…”

“…Such regular spheres have a large size distribution, and the smallest spheres could coincide with the dimension of single crystallites, as indicated by XRD, whereas the largest ones are in the micrometer range. The morphologies of both the CP and PE nanocrystalline samples are different from the porous, spongelike one found for nanocrystalline GGG samples prepared by a combustion synthesis [10].…”

“…After a suitable heat treatment, the obtained powders result to be single phase with a garnet structure. Size distributions and morphological properties of the nanocrystalline samples are obtained from scanning electron microscopy (SEM) images and compared with previous results obtained for GGG nanocrystalline powders prepared by combustion synthesis [10] or other methods. Laser excited Stokes and upconversion emission spectra have been measured and discussed.…”

Structural and luminescence investigation on gadolinium gallium garnet nanocrystalline powders prepared by solution combustion synthesis

“…• C for 6 h of the GGG:1 mol% Ho, with a second garnet-type phase, leads to the formation of a pure GGG cubic phase [36]. The fit for this model with the experimental data can be seen in figure 2(b).…”

“…In our previous work [36] we studied a series of GGG samples, obtained via solution combustion synthesis, doped with different lanthanide ions (Tm, Er, Ho, Eu, Sm, Nd, Pr) and with different concentrations (1, 5, 10 mol%). For all samples XRD analysis revealed the presence of the cubic GGG phase.…”