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Photocatalytic, structural and optical properties of mixed anion solid solutions Ba 3 Sc 2−x In x O 5 Cu 2 S 2 and Ba 3 In 2 O 5 Cu 2 S 2−y Se y
Nine members of two contiguous solid solutions, Ba 3 Sc 2−x In x O 5 Cu 2 S 2 and Ba 3 In 2 O 5 Cu 2 S 2−y Se y ( x , y = 0, 0.5, 1, 1.5 and 2), were synthesised at temperatures between 800 °C and 900 °C by stoichiometric combination of binary precursors. Their structures were determined by Rietveld...
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| Published in: | Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-10, Vol.8 (38), p.19887-19897 |
|---|---|
| Main Authors: | , , , , , |
| Format: | Article |
| Language: | English |
| Citations: | Items that this one cites Items that cite this one |
| Online Access: | Get full text |
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| Summary: | Nine members of two contiguous solid solutions, Ba
3
Sc
2−x
In
x
O
5
Cu
2
S
2
and Ba
3
In
2
O
5
Cu
2
S
2−y
Se
y
(
x
,
y
= 0, 0.5, 1, 1.5 and 2), were synthesised at temperatures between 800 °C and 900 °C by stoichiometric combination of binary precursors. Their structures were determined by Rietveld refinement of X-ray powder diffraction data and found to adopt the SmNi
3
Ge
3
structure with
I
4/
mmm
symmetry. Approximate Vegard law relationships were found within each solution between the lattice parameters and composition, with an observed cell volume of 466.4 Å
3
for Ba
3
Sc
2
O
5
Cu
2
S
2
increasing to 481.0 Å
3
for Ba
3
In
2
O
5
Cu
2
S
2
and finally to 499.0 Å
3
for Ba
3
In
2
O
5
Cu
2
Se
2
. In the first solid solution, this volume increase is driven by the replacement of scandium by the larger indium ion, generating increased strain in the copper chalcogenide layer. In the second solution the substitution into the structure of the larger selenium drives further volume expansion, while relieving the strain in the copper chalcogenide layer. Band gaps were estimated from reflectance spectroscopy and these were determined to be 3.3 eV, 1.8 eV, and 1.3 eV for the three end members Ba
3
Sc
2
O
5
Cu
2
S
2
, Ba
3
In
2
O
5
Cu
2
S
2
, and Ba
3
Sc
2
In
2
O
5
Cu
2
Se
2
, respectively. For the intermediate compositions a linear relationship between band gap size and composition was observed, driven in the first solution by the introduction of the more electronegative indium lowering the conduction band minimum and in the second solution by the substitution of the electropositive selenium raising the valance band maximum. Photocatalytic activity was observed in all samples under solar simulated light, based on a dye degradation test, with the exception of Ba
3
In
2
O
5
Cu
2
Se
1.5
S
0.5
. The most active sample was found to be Ba
3
Sc
2
O
5
Cu
2
S
2
, the material with the largest band gap. |
|---|---|
| ISSN: | 2050-7488 2050-7496 |
| DOI: | 10.1039/D0TA06629J |