TY - JOUR
T1 - Structure of cerium phosphate glasses
T2 - Molecular dynamics simulation
AU - Du, Jincheng
AU - Kokou, Leopold
AU - Rygel, Jennifer L.
AU - Chen, Yongsheng
AU - Pantano, Carlo G.
AU - Woodman, Robert
AU - Belcher, James
PY - 2011/8
Y1 - 2011/8
N2 - We performed molecular dynamics (MD) simulations of the structure and properties of cerium-containing phosphosilicate, aluminophosphate, and aluminophosphosilicate glasses based on recent spectroscopic data that revealed 95% of cerium ions in such glasses are Ce3+. New Ce3+- and Ce4+-O2- potentials were developed and used in the MD simulations of these cerium-containing glasses with mixed glass formers. The local environments around cerium ions and network-forming cations, the medium range structure including glass-forming network Qn distribution, clustering, and second coordination shell around cerium ions have been carefully characterized. The results showed a longer Ce-O bond length and larger coordination number for Ce3+ than Ce4+ (2.48 and 6.4 vs. 2.24Å and 5.8, respectively). Around 5% of Si4+ ions were found to be in fivefold and sixfold coordination states in cerium phosphosilicate glasses, rather than the usual fourfold in silicate glasses. At the same time, the silicon-oxygen polyhedra were highly polymerized (over 80% of Q4) due to the presence of phosphorus oxide. Aluminum ions were found to be coordinated by four-, five-, and six oxygen ions, with an average coordination number of around 4.2. In both oxidation states, cerium ions were found to be preferentially surrounded by phosphorus-oxygen tetrahedra, which form a kind of solvation shell around them. The preference of network-forming cations around cerium ions in the second coordination shell was found to decrease in the sequence phosphorus, aluminum, silicon.
AB - We performed molecular dynamics (MD) simulations of the structure and properties of cerium-containing phosphosilicate, aluminophosphate, and aluminophosphosilicate glasses based on recent spectroscopic data that revealed 95% of cerium ions in such glasses are Ce3+. New Ce3+- and Ce4+-O2- potentials were developed and used in the MD simulations of these cerium-containing glasses with mixed glass formers. The local environments around cerium ions and network-forming cations, the medium range structure including glass-forming network Qn distribution, clustering, and second coordination shell around cerium ions have been carefully characterized. The results showed a longer Ce-O bond length and larger coordination number for Ce3+ than Ce4+ (2.48 and 6.4 vs. 2.24Å and 5.8, respectively). Around 5% of Si4+ ions were found to be in fivefold and sixfold coordination states in cerium phosphosilicate glasses, rather than the usual fourfold in silicate glasses. At the same time, the silicon-oxygen polyhedra were highly polymerized (over 80% of Q4) due to the presence of phosphorus oxide. Aluminum ions were found to be coordinated by four-, five-, and six oxygen ions, with an average coordination number of around 4.2. In both oxidation states, cerium ions were found to be preferentially surrounded by phosphorus-oxygen tetrahedra, which form a kind of solvation shell around them. The preference of network-forming cations around cerium ions in the second coordination shell was found to decrease in the sequence phosphorus, aluminum, silicon.
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U2 - 10.1111/j.1551-2916.2011.04514.x
DO - 10.1111/j.1551-2916.2011.04514.x
M3 - Article
AN - SCOPUS:80051544247
SN - 0002-7820
VL - 94
SP - 2393
EP - 2401
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
IS - 8
ER -