Turku University Centre for Materials and Surfaces (MatSurf), FI-20014 Turku, ... 10 12 14 16 18 20 22 24 26. 200. 400. 600. 800. 1000. 1200. P = 800 W. In n e ... rb . U n its. Energy / eV. CaSO. 4. Figure S5. SR-XANES spectra at the sulfur ...
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry C. This journal is © The Royal Society of Chemistry 2018
Persistent luminescence warm-light LEDs based on Ti-doped RE2O2S materials prepared by rapid and energy-saving microwave-assisted synthesis
José Miranda Carvalho,a,b Cássio Cardoso Santos Pedroso,c Ian Pompermayer Machado,b Jorma Hölsä,d Lucas Carvalho Veloso Rodrigues,b Pawel Głuchowski,e Mika Lastusaari,f,g Hermi Felinto Brito*b a. Institute of Physics, University of São Paulo, 05508-000, São Paulo-SP, Brazil b. Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, 05508-900, São Paulo-SP, Brazil c. Department of Biochemistry, Institute of Chemistry, University of São Paulo, 05508-900, São Paulo-SP, Brazil d. University of the Free State, Department of Physics, Bloemfontein, ZA-9300, South Africa. e. Institute of Low Temperature and Structure Research, PL-50422 Wroclaw, Poland f. University of Turku, Department of Chemistry, FI-20014 Turku, Finland g. Turku University Centre for Materials and Surfaces (MatSurf), FI-20014 Turku, Finland
Supporting Information
Figure S1. Microwave-assisted solid-state synthesis setup to obtain the oxysulfide materials. Both external and internal crucible are made from alumina. The microwave susceptor used was granular carbon. The thermal insulation is a low-density aluminosilicate brick. All the materials were prepared in a conventional domestic microwave oven.
Inner crucible temp / °C
1200
1000
800
600
400
200
P = 900 W
0
2
4
6
P = 800 W
8
10
12
14
16
18
20
22
24
26
Time / s Figure S2. Correlation between the temperature of the sample crucible (surrounded by the activated charcoal) and the microwave exposition time. Each temperature point was measured with a Homis H811-451 hand pyrometer.
2+
3
Intensity / 10 counts
La2O2S:Ti,Mg (1.5 & 4.5 mole-%) 2
4
2+
: 1.61332 Å (SR)
Y2O2S:Ti,Mg (1.5 & 4.5 mole-%) : 1.61332 Å (SR)
Exp. Calc. Diff. La2O2S
Exp. Calc. Diff. Y2O2S
1
2
0 0
-1 40
60
80
100
120
40
60
80
100
120
Figure S3. X-ray powder diffraction patterns of the RE2O2S:Ti,Mg2+ [RE: La (left) and Y (right)] materials obtained with 25 minutes of microwave irradiation by microwave-assisted solidstate synthesis, with the Rietveld refinement results.
Y2O2S
Intensity / Arb. Units
10
300 % excess of sulfur 8
6
4
2
0 10
20
30
40
50
60
70
80
CuK1 2 / Degree
Figure S4. X ray powder diffraction pattern of the Y2O2S material obtained with 300% of excess of sulfur in the precursor, using the same pre adjusted microwave program.
4
Intensity / Arb. Units
FeS
S
2 NaSO3
CaSO4
0
2460
2480
2500
2520
2540
Energy / eV Figure S5. SR-XANES spectra at the sulfur K-edge of the standards materials for sulfur speciation.
RE2O2S:Ti,Mg
1,25
2+
2,0
RE2O2S:Ti,Mg
VUV first derivative 1,5
1,00
Y 0,75
Gd 0,50
Intensity / Arb. Units
Intensity / Arb. Units
VUV Excitation spectra
Y
Eg: 4.9 eV
1,0
Gd 4.6 0,5
La
La 0,0
0,25
4
5
6
Energy / eV
7
8
2+
4
4.5
5
6
7
8
Energy / eV
Figure S6. Synchrotron Radiation VUV-UV spectra (left) and derivative of the intensity (right) of the RE2O2S:Ti,Mg2+ materials obtained by the microwave-assisted solid-state method.
Normalized Intensity / Arb. Units
2,0
1,5
AlGaN LED @ RE2O2S:Ti,Mg
2+
exc: 280 nm
298 K
RE: Gd 1,0
0,5
Y 0,0 400
450
500
550
600
650
700
750
Wavelength / nm Figure S7. Photoluminescence emission spectra of the light emitting diodes devices fabricated from a AlGaN LED covered with a polydimethylsiloxane matrix doped with 10 %-wt of the RE2O2S:Ti,Mg2+ (RE: Gd and Y) materials.
