| Abstract
| - The dehydratation process of layered lanthanide silicates K3[LnSi3O8(OH)2], Ln = Y, Eu, Tb, and Er, andthe structural characterization of the obtained small-pore framework K3LnSi3O9, Ln = Y, Eu, Tb, and Ersolids, named AV-23, have been reported. The structure of AV-23 has been solved by single-crystal X-raydiffraction (XRD) methods and further characterized by chemical analysis, thermogravimetry, scanning electronmicroscopy, and 29Si MAS NMR. The photoluminescence (PL), radiance, and lifetime values of AV-23 havebeen studied and compared with those of AV-22. Both materials have a similar chemical makeup and structuressharing analogous building blocks, hence providing a unique opportunity for rationalizing the evolution ofthe PL properties of lanthanide silicates across dimensionality. Although Tb-AV-23 contains a singlecrystallographic Tb3+ site, PL spectroscopy indicates the presence of Ln3+ centers in regular framework positionsand in defect regions. PL evidence suggests that Eu-AV-23 contains a third type of Ln3+ environment, namely,Eu3+ ions replacing K+ ions in the micropores. The radiance values of the Tb-AV-22 and Tb-AV-23 samplesare of the same order of magnitude as those of standard Tb3+ green phosphors. For the samplesK3(Y1-aEraSi3O9), a = 0.005−1, efficient emission and larger 4I13/2 lifetimes (ca. 7 ms) are detected for lowEr3+ content, indicating that the Er3+−Er3+ interactions become significant as the Er3+ content increases.
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