Detail of "14286-95-4"

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b-Y2Si2O7, a new thortveitite-type compound, determined at 100 and 280 K

b-Y2Si2O7, a new thortveitite-type compound, determined at 100 and 280 K. Redhammer, Guenther J.; Roth, Georg (Institute of Crystallography, Aachen D-52056, Germany). Acta Crystallographica, Section C: Crystal Structure Communications, C59(10), i103-i106 (English) 2003 Blackwell Publishing Ltd. CODEN: ACSCEE. ISSN: 0108-2701. DOCUMENT TYPE: Journal CA Section: 75 (Crystallography and Liquid Crystals) Section cross-reference(s): 78 A new form of Y2Si2O7 (diyttrium heptaoxodisilicate) was synthesized which is isotypic with thortveitite, Sc2Si2O7, and crystallizes in the centrosym. space group C2/m, both at 100 and 280 K The Y3+ cation occupies a distorted octahedral site, with Y-O bond lengths in the range 2.239(2)-2.309(2) ?. The SiO4 tetrahedron is remarkably regular, with Si-O bond lengths in the range 1.619(2)-1. 14286-95-4 which is the cas registry number is also used here.630(2) ?. The bridging O atom of the Si2O7 pyrosilicate group shows a large anisotropic displacement perpendicular to the Si-O bond. Changes in lattice and structural parameters upon cooling are small with, however, a distinct decrease of the anisotropic displacement of the bridging O atom. Structure soln. and refinement in the noncentrosym. space group C2 are possible but do not yield a significantly different structure model. The Si-O-Si bond angle of the isolated Si2O7 groups is 179.2(1)° at 280 K in C2 and 180° per symmetry in C2/m. The C2/m structure model is favored. Crystallog. data are given. .

Synthesis of Y2Si2O7:Eu nanocrystal and its optical properties

All Rights Reserved. Synthesis of Y2Si2O7:Eu nanocrystal and its optical properties. Zhou, Pingle; Yu, Xibin; Yang, Liangzhun; Yang, Shiping; Gao, Wenjie ( Department of Chemistry, Shanghai Normal University, Shanghai 200234, Peop. Rep. China). Journal of Luminescence, 124(2), 241-244 (English) 2007 Elsevier B. 14286-95-4 and 7440-53-1 are cas registry numbers. These chemicals are also mentioned in this article.V. CODEN: JLUMA8. ISSN: 0022-2313. DOCUMENT TYPE: Journal CA Section: 73 (Optical, Electron, and Mass Spectroscopy and Other Related Properties) Section cross-reference(s): 75 Nanocryst. Y2Si2O7:Eu phosphor with an av. size about 60 nm is easily prepd. using SiO2 aerogel as raw material under ultrasonic irradn. and annealing temp. at 300-600° and this nanocryst. decomps. into Y2O3:Eu and SiO2 by heat treatment at 700-900°. The excitation broad band centered at 283 and 254 nm results from Eu3+ substituting for Y3+ in Y2Si2O7 and Y2O3/SiO2, resp. Compared with Y2O3:Eu/SiO2 cryst., the PL excitation and emission peaks of Y2Si2O7:Eu nanocryst. red-shift and lead to the enhance of its luminescence intensity due to the different chem. surroundings of Eu3+ in above nanocrystallines. The decrease of PL intensity may be ascribed to quenching effect resulting from more defects in Y2O3:Eu/SiO2 cryst. .