New phases Bi 12.5 Ln 1.5 ReO 24.5 : Thermodynamics and influence of dopant size on lattice energy (Ln – lanthanide)

Abstract

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Polymorphism and Visible-Light-Driven Photocatalysis of Doped Bi2O3:M (M = S, Se, and Re)

“…The cubic compound Bi 14 O 20 (ReO 4.5 ) ( 3c ) with an oxygen-defective fluorite -type structure represents a rare-earth-free compound of the previously reported Bi 12.5 Ln 1.5 ReO 24.5 (Figure ). ,− The unit cell length of Bi 14 O 20 (ReO 4.5 ) ( 3c ) with a f = 5.6469(3) Å is very close to that of Bi 12.5 La 1.5 ReO 24.5 with a f = 5.6456(3) Å because of the similar ionic radii of Bi 3+ ( r ion = 1.03 Å, CN = 6) and La 3+ ( r ion = 1.032 Å, CN = 6) . The substitution of Bi 12.5 Ln 1.5 ReO 24.5 with lanthanides of lower ionic radii results in a decrease of the unit cell length “ a f ” in accordance with the lanthanoid contraction (Figure ).…”

“…The substitution of Bi 12.5 Ln 1.5 ReO 24.5 with lanthanides of lower ionic radii results in a decrease of the unit cell length “ a f ” in accordance with the lanthanoid contraction (Figure ). ,− The incorporation of the dopants into the δ-Bi 2 O 3 -type lattice of the compounds 1c – 5c is confirmed by IR- and Raman spectroscopy (Figures and ). In the IR spectra, cubic Bi 14 O 20 (SO 4 ) ( 1c ) and Bi 14 O 20 (SeO 4 ) ( 2c ) show characteristic vibration bands for the corresponding chalcogenate groups ([SO 4 ] 2– : 1057 cm –1 (ν 3 ), 962 cm –1 (ν 1 ), and 599 cm –1 (ν 4 ); , [SeO 4 ] 2– : 836 cm –1 (ν 1 )).…”

“…Correlation between the ionic radius “ r ion ” of Ln 3+ (Ln = La, Pr, Nd, Sm, Gd, Dy, Ho, and Lu; CN = 6) and the cell parameter “ a f ” in cubic Bi 12.5 LnO 20 (ReO 4.5 ) ,− in comparison to Bi 14 O 20 (ReO 4.5 ) ( 3c ). Based on a diagram with permission from reference (Copyright 2014 Elsevier) and reference (Copyright 2012 Elsevier).…”

“…99,102 Among them, Bi 14 WO 24 is the only ternary example, for which a cubic modification was additionally reported. 103,104 In the case of compounds related to Bi 14 ReO 24.5 , the cubic δphase is reported for quaternary compounds with the composition Bi 12.5 Ln 1.5 ReO 24.5 (Ln = Y, 12,105 La, 12,105,106 Pr, 106 Nd, 12,105 Sm, 107 Eu, 12 Gd, 108 Dy, 109 Ho, 110 Er, 12,111,112 Yb, 113 and Lu 112,114,115 ). Semi and nonmetalstabilized δ-Bi 2 O 3 is only known for the binary systems of Bi 2 O 3 −B 2 O 3 14 and Bi 2 O 3 −BiPO 4 , respectively.…”