Local Disorder and Tunable Luminescence in Sr 1-

Transcription

1 Local Disorder and Tunable Luminescence in Sr 1- x/2al 2-x Si x O 4 (0.2 x 0.5) Transparent Ceramics Alberto J. Fernandez-Carrion, a Kholoud Al Saghir, a Emmanuel Veron, a Ana I. Becerro, b Florence Porcher, c Wolfgang Wisniewski, d Guy Matzen, a Franck Fayon,* a Mathieu Allix* a. a. CNRS, CEMHTI UPR3079, Univ. Orléans, F Orléans, France. b. Instituto de Ciencia de Materiales de Sevilla (CSIC-US), Avenida Américo Vespucio s/n, Isla de La Cartuja, Sevilla, Spain. c. Laboratoire Léon Brillouin CEA-CNRS UMR12, CEA/Saclay, Gif-sur-Yvette Cedex, France d. Otto-Schott-Inst.Jena Univ., Fraunhoferstr 6, D Jena, Germany Corresponding Author *(F.F.) franck.fayon@cnrs-orleans.fr *(M.A.) mathieu.allix@cnrs-orleans.fr 1

2 Figure SI1. Localization of the new Sr 1-x/2 Al 2-x Si x O 4 (0 < x 0.5, green, blue and red dots) solid solution in the SrO Al 2 O 3 SiO 2 ternary system, along with the Sr 1+x/2 Al 2+x Si 2 x O 8 (0 < x 0.4, grey dots) compositions previously studied by Al-Saghir et al. (Chem. Mater., 2013, 25, ). 2

3 Figure SI2. X-ray diffraction data of the Eu-doped Sr 0.9 Al 1.8 Si 0.2 O 4 (x = 0.2) glass composition. 3

4 Figure SI3. Normalized DSC thermograms recorded for different Sr 1-x/2 Al 2-x Si x O 4 (x = 0.2, 0.4 and 0.5) glass compositions. T g and T c correspond respectively to glass transition and crystallization temperatures. For the x = 0.2 glass composition sample, we stipulate that the glass transition is masked by the onset of the crystallization peak, illustrating the low glass stability and glass forming ability of this composition. 4

5 a) b) Figure SI4. (a) Optical microscopy photographs and corresponding SEM micrographs of the Eu-doped Sr 0.8 Al 1.6 Si 0.4 O 4 glass annealed at 985 C for different times. (b) Crystallization percentage calculated from the optical microscope observation. The values were calculated as the ratio between the thickness of the crystallized part observed from both faces and the total thickness of the sample. 5

6 Figure SI5. (a) SEM-micrograph of the immediate surface of a Sr 0.75 Al 1.5 Si 0.5 O 4 ceramic sample polished after annealing at 1010 C for 7h. EBSD-patterns obtained from (b) the untreated surface and (c) a polished cross section. 6

7 Figure SI6. SEM-micrograph of a cross section of a Sr 0.75 Al 1.5 Si 0.5 O 4 (x = 0.5) ceramic annealed at 1010 C for 7h. The orientation+iq-map of an EBSD-scan performed on the area is superimposed. 7

8 Figure SI7. Laboratory X-Ray powder diffraction patterns collected on the Eu-doped Sr 1-x/2 Al 2-x Si x O 4 (x = 0.2, 0.4 and 0.5) ceramics showing the presence of extra reflections for x 0. In blue, diagram of SrAl 2 O 4 (x = 0) calculated from ICSD structural file (Avdee et al., J. Sol. St. Chem., 2007, 180, ). (bottom) Enlargement of the low angle area. 8

9 Figure SI8. Experimental (red circles) and fitted (green solid line) profiles of laboratory X-ray diffraction data of the Sr 0.75 Al 1.5 Si 0.5 O 4 (x = 0.5) ceramic. Space group P-62c, a = (3) Å, c = (8) Å (GOF = 2.28, R p = 8.51%, R wp = 11.12%). 9

10 Figure SI9. Experimental (red circles) and fitted (green solid line) profiles of laboratory synchrotron powder diffraction data of the Sr 0.9 Al 1.8 Si 0.2 O 4 (x = 0.2) ceramic. Space group P-62c, a = (1) Å, c = (2) Å (GOF = 4.19, R p = 15.4%, R wp = 16.3%). 10

11 Figure SI10. Evolution of the Sr 1-x/2 Al 2-x Si x O 4 a and c cell parameters as a function of x. The cell parameters of the x = 0 material (ICSD structural file - hexagonal P63 cell, a = Å and c = Å, Avdee et al., J. Sol. St. Chem., 2007, 180, ) has been doubled to compare the cell parameters with the superstructure observed for the x = 0.2, 0.4 and 0.5 compositions. The dotted red lines are a guide for the eye. 11

12 a) x = (Sr Al Si O 4 ) Model 1 Model 2 Model 3 Model 4 b) x = 0.5 (Sr 0.75 Al 1.5 Si 0.5 O 4 ) Model 1 Model 2 Model 3 Model 4 2 Figure SI11. Selected DFT-geometry-optimized structural models for (a) the x = and (b) x = 0.5 compositions. In (a) the 1x1x2 cell contains 1 Sr vacancy in one of the two Sr4 positions and 2 Si atoms in the 24 T sites. In (b) the cell contains 3 Sr vacancies (2 in Sr4 and 1 in Sr5 positions) and 6 tetrahedral sites occupied by Si atoms. The blue and pink tetrahedra correspond to AlO 4/2 - and SiO 4/2 units and the bridging oxygen atoms are shown in red. The Sr atoms and vacancies, insuring charge balance in the fully-polymerized network and located in the channels, are shown as green and empty balls. 12

13 a Intensity (a.u.) x=0.5 x= Wavelength (nm) x=0.2 b Intensity (a.u.) x=0.5 x=0.4 x= Wavelength (nm) Figure S12: Excitation spectra of the Sr 1-x/2 Al 2-x Si x O 4 ceramics recorded at a) λ em = 614 nm and at b) λ em = 475 nm. 13

14 x=0.2 Eu3d Eu +3 Intensity (a.u.) exp. Eu +3 Eu +2 plasmons backgrd. fitting plasmon Eu Binding Energy (ev) x=0.4 Eu3d Intensity (a.u.) exp. Eu +3 Eu +2 plasmons backgrd. fitting plasmon Eu +3 Eu Binding Energy (ev) x=0.5 Eu3d Intensity (a.u.) exp. Eu +3 Eu +2 plasmons backgrd. fitting plasmon Eu +3 Eu Binding Energy (ev) Figure S13: Experimental and fitted Eu3d XPS spectra of the Sr 1-x/2 Al 2-x Si x O 4 powder ceramics. 14

15 Table SI1. Interatomic distances for Sr 0.8 Al 1.6 Si 0.4 O 4 (x = 0.4) obtained from synchrotron powder diffraction (11BM-APS) data collected at ambient temperature. Al/Si tetahedron (Å) Sr polyhedron (Å) (Al/Si)1-O (8) Sr1-O3 (x3) 2.64(1) (Al/Si)1-O (1) Sr1-O5 (x6) 2.62(1) (Al/Si)1-O (6) Sr2-O4 (x6) 2.91(3) (Al/Si)1-O (4) Sr3-O1 (x3) 2.58(1) (Al/Si)2-O (2) Sr3-O4 (x3) 2.76(1) (Al/Si)2-O (3) Sr4-O3 (x3) 2.65(1) (Al/Si)2-O (7) Sr5-O2 (x3) 2.503(5) (Al/Si)2-O5 1.70(1) 15

16 Table SI2. Atomic coordinates and values of occupancy factor determined for Sr 0.9 Al 1.8 Si 0.2 O 4 (x = 0.2) from Rietveld refinement of synchrotron powder diffraction data collected at ambient temperature. Space group P-62c, a = (1) Å, c = (2) Å (GOF = 4.19, R p = 15.4%, R wp = 16.3%). Atom Site x y z U iso (Å 2 ) Occ. Sr1 2c (6) Sr2 2b (6) Sr3 4f (9) (2) Sr4 2d (4) (4) Sr5 2a (4) (4) Al1 12i (4) (5) (2) (5) 0.9 Si1 12i (4) (5) (2) (5) 0.1 Al2 12i (6) (6) (3) (7) 0.9 Si2 12i (6) (6) (3) (7) 0.1 O1 12i (15) (3) (5) (4) 1 O2 6g (12) (4) 1 O3 6h (3) (18) (4) 1 O4 12i (3) (3) 0.126(1) (4) 1 O5 12i (3) (12) (6) (4) 1 Table SI3. Interatomic distances for Sr 0.9 Al 1.8 Si 0.2 O 4 (x = 0.2) obtained from Rietveld refinement of synchrotron powder diffraction data collected at ambient temperature. Al/Si tetahedron (Å) Sr polyhedron (Å) (Al/Si)1-O (5) Sr1-O3 (x3) 2.654(2) (Al/Si)1-O (3) Sr1-O5 (x6) 2.703(2) (Al/Si)1-O (4) Sr2-O4 (x6) 2.619(2) (Al/Si)1-O (4) Sr3-O1 (x3) 2.559(1) (Al/Si)2-O (6) Sr3-O5 (x3) 2.782(2) (Al/Si)2-O (4) Sr4-O3 (x3) 2.628(2) (Al/Si)2-O (5) Sr5-O2 (x3) 2.423(1) (Al/Si)2-O (5) 16

17 Table SI4. Atomic coordinates and values of occupancy factor determined for Sr 0.75 Al 1.5 Si 0.5 O 4 (x = 0.5) from Rietveld refinement of laboratory X-ray diffraction data collected at ambient temperature. Space group P-62c, a = (3) Å, c = (8) Å (GOF = 2.28, R p = 8.51%, R wp = 11.12%). Atom Site x y z U iso (Å 2 ) Occ. Sr1 2c (8) 1.00 Sr2 2b (9) 1.00 Sr3 4f (10) (8) 1.00 Sr4 2d (1) Sr5 2a (1) Al1 12i (4) (3) (2) (11) 0.75 Si1 12i (4) (3) (2) (11) 0.25 Al2 12i (5) (6) (4) (18) 0.75 Si2 12i (5) (6) (4) (18) 0.25 O1 12i (7) 0.452(1) (3) (8) 1 O2 6g (9) (8) 1 O3 6h (12) (12) (8) 1 O4 12i (10) (11) (4) (8) 1 O5 12i (13) ( (3) (8) 1 Table SI5. Interatomic distances for Sr 0.75 Al 1.5 Si 0.5 O 4 (x = 0.5) obtained from Rietveld refinement of laboratory X-ray powder diffraction data collected at ambient temperature. Al/Si tetahedron (Å) Sr polyhedron (Å) (Al/Si)1-O1 1.84(1) Sr1-O3 (x3) 2.58(1) (Al/Si)1-O2 1.70(1) Sr1-O5 (x6) 2.74(1) (Al/Si)1-O4 1.79(1) Sr2-O4 (x6) 2.61(1) (Al/Si)1-O5 1.75(1) Sr3-O1 (x3) 2.62(1) (Al/Si)2-O1 1.62(1) Sr3-O5 (x3) 2.71(1) (Al/Si)2-O3 1.74(1) Sr5-O2 (x3) 2.28(1) (Al/Si)2-O4 1.63(1) Sr4-O3 (x3) 2.66(1) (Al/Si)2-O5 1.68(1) 17