Observation of cluster formation of rare earth ions in wide band gap fluorine dielectric crystals using transmission electron microscopy

Observation of nanostructured cluster formation of Tm ions in CaF2 crystals

“…These results are in agreement with previous measurements taken from the broad optical spectra of RE ions in host matrices [6]. The degree of the inhomogeneous distribution of the Tm ions, and the clustering in the host crystal, depends on the heat flow gradients across the interfacial layer between the melt and the solid phase, and also on the temperature gradient and stability in the crucible and the spatial correlation of density fluctuations in the liquid phase at the interface.…”

“…The homogeneity of the concentration of the RE ions determine the refractive index variation, and therefore set the limits of the optical performance of these materials. Thus, the efficiency of optical systems depends on several factors: the structure of the levels of the 4f n−1 5d electronic configuration of the RE ions [3,4], the homogeneous distribution of the RE ion concentration inside the crystal volume [5,6], and the possible agglomeration of the RE ions at the ionic sites of the host matrix, because the RE * Corresponding author. Tel.…”

Long-term oxidization and phase transition of InN nanotextures

“…It was found that they exhibit a sharp Gaussian distribution at the nanoscale (approx. 10 nm) [ 34 ]. It is unlikely therefore that long 3D crystal structures are grown either in the plume, or directly on the Si substrate with PLD.…”

“…Three different nanostructured groups with average size of 5 (A), 25 (B), and 40 nm (C) are identified, Figure 6a, b , although larger crystal domains are grown through the aggregation of small nanocrystal domains (<5 nm). Furthermore, crystal structures with their Laue levels slightly rotated with respect to each other (Figure 6b, D ) should correspond to a superposition of uncorrelated crystal nanostructures [ 34 ] (separated by a relatively large distance in comparison to the correlation length). The HRTEM images indicate the superposition of crystal areas of different contrast and with parallel Laue levels, indicated within the periphery of the circles C1 and C2 (Figure 5 ) and within the areas E and F (Figure 6a ).…”