Ostwald-ripening and particle size focussing of sub-10 nm NaYF 4 upconversion nanocrystals

Transcription

1 Electronic Supplementary Material (ESI) for Nanoscale. This journal is The Royal Society of Chemistry 2014 Supplementary Information for: Ostwald-ripening and particle size focussing of sub-10 nm NaYF 4 upconversion nanocrystals Thorben Rinkel, Jörg Nordmann, Athira Naduviledathu Raj and Markus Haase* Institute of Chemistry of New Materials, Osnabrück University, Barbarastraße 7, Osnabrück, Germany Figure S1: Size histograms of α-nayf 4 :Yb,Er, α-na 5 Y 9 F 32 :Yb,Er, and β-nayf 4 :Yb,Er nanoparticles after Ostwald-ripening at 300 C in oleic acid/octadecene (from left to right). The mean size (d 0 ) and the relative standard deviation (σ/d 0 ) are displayed in each image. S1

2 Figure S2: Upper row: X-ray powder diffraction (XRD) data of sub-10 nm nanocrystals of α- NaYF 4 :Yb,Er, α-na 5 Y 9 F 32 :Yb,Er, and β-nayf 4 :Yb,Er (from left to right). Lower row: Particles of the upper row after Ostwald ripening in oleic acid/octadecene at 300 C. Vertical lines correspond to the reference data of NaYF 4 (red: cubic α-phase, PDF-Nr ; blue: hexagonal β-phase, PDF-Nr ). S2

3 Figure S3: Rietveld refinement of the XRD data of NaYF 4 :Yb,Er particles obtained by heating sub- 10 nm α-nayf 4 :Yb,Er particles with different compositions at 300 C in oleic acid/octadecene. Top: α- NaYF 4 :Yb,Er particles prepared with a 8:1:11 molar ratio of sodium oleate (Na-OA), rare-earth oleate (RE-OA) and ammonium fluoride (NH 4 F) after 40 min of heating: β-nayf 4 :Yb,Er particles with a mean size of 5.6 nm are obtained. Middle and bottom: α-phase particles prepared with a molar ration of 2.5:1:4 are not converted after 10 min of heating (middle) but partially converted after 65 min (bottom). The measured intensity (red circles), calculated intensity (black line), the residuum (blue line) and the peak positions (green vertical lines) are displayed for each sample. S3

4 Figure S4: Conversion of α-phase particles to the β-phase after different times of heating at 300 C in oleic acid/octadecene. Displayed are the X-ray powder diffraction (XRD) data of particles prepared with sodium oleate (Na-OA), rare-earth oleate (RE-OA) and ammonium fluoride (NH 4 F) in a molar ratio of 2.5:1:4 (Na-OA : RE-OA : NH 4 F). Vertical lines correspond to the reference data of NaYF 4 (red: cubic α-phase, PDF-Nr ; blue: hexagonal β-phase, PDF-Nr ). S4

5 Figure S5: Ostwald-ripening of sub-10 nm nanocrystals of undoped α-nayf 4 in oleic acid/octadecene at 300 C. The figure displays the temporal evolution of the mean size of the α-phase particles (filled stars), the mean size of β-phase particles nucleating in the solution (open cubes) and the molar fractions of the two phases (circles). Lines are to guide the eye. S5

6 Figure S6: Upper row: X-ray powder diffraction (XRD) data of the α-phase products obtained by heating sub-10 nm particles of α-na 5 Y 9 F 32, α-na 5 Yb 9 F 32, and α-na 5 Er 9 F 32 at 300 C in oleic acid/octadecene (from left to right). Lower row: β-phase products obtained by heating sub-10 nm particles of α-nayf 4, α-naybf 4, and α-naerf 4 at 300 C in oleic acid/octadecene (from left to right). Vertical lines correspond to the reference data of NaYF 4 (red: cubic α-phase, PDF-Nr ; blue: hexagonal β-phase, PDF-Nr ). S6

7 Figure S7: Size histograms of α-phase product particles obtained by heating sub-10 nm particles of α- Na 5 Y 9 F 32, α-na 5 Yb 9 F 32, and α-na 5 Er 9 F 32 at 300 C in oleic acid/octadecene (upper row, from left to right). Lower row: Size histograms of β-phase particles obtained by heating sub-10 nm particles of α- NaYF 4, α-naybf 4, and α-naerf 4 at 300 C in oleic acid/octadecene (from left to right). The mean size (d 0 ) and the relative standard deviation (σ/d 0 ) are displayed in each image. S7

8 Figure S8: X-ray powder diffraction (XRD) data of sub-10 nm nanocrystals of α-nayf 4 :Yb,Er particles prepared with different molar ratios of sodium oleate (Na-OA), rare-earth oleate (RE-OA) and ammonium fluoride (NH 4 F). The molar ratios (Na-OA : RE-OA : NH 4 F) are given in each diffractogram. Vertical lines correspond to the reference data of NaYF 4 (cubic α-phase, PDF-Nr ). S8

9 Figure S9: X-ray powder diffraction (XRD) data of β-nayf 4 :Yb,Er particles with different mean size prepared by Ostwald-ripening of α-nayf 4 :Yb,Er particles with different compositions. The molar ratios of sodium oleate (Na-OA), rare-earth oleate (RE-OA) and ammonium fluoride (NH 4 F) employed in the synthesis of the α-phase particles are displayed in each diffractogram (Na-OA : RE-OA : NH 4 F). Vertical lines correspond to the reference data of NaYF 4 (hexagonal β-phase, PDF-Nr ). S9

10 Figure S10: Size histograms of β-nayf 4 :Yb,Er particles prepared by Ostwald-ripening of α- NaYF 4 :Yb,Er particles with different compositions. The molar ratios of sodium oleate (Na-OA), rareearth oleate (RE-OA) and ammonium fluoride (NH 4 F) used in the synthesis of the α-phase particles are displayed in each figure (Na-OA : RE-OA : NH 4 F). The mean size (d 0 ) and the relative standard deviation (σ/d 0 ) are displayed in each image. S10

11 Figure S11: Overview TEM-images of β-nayf 4 :Yb,Er particles obtained by heating differently prepared α-phase particles in oleic acid/octadecene at 300 C. The molar ratio of Na-OA, RE-OA and NH 4 F used in the synthesis of the α-phase particles is given in each TEM image (Na-OA : RE-OA : NH 4 F). S11

12 Figure S12: TEM-images of β-nayf 4 :Yb,Er particles prepared by heating α-phase particles in the absence (left) or in the presence (right) of additional sodium oleate and NH 4 F. A molar ratio of 1.5 : 1 : 4.5 (Na-OA : RE-OA : NH 4 F) was used in the synthesis of the α-phase particles. S12

13 Figure S13: Size histograms of β-nayf 4 :Yb,Er particles prepared by Ostwald-ripening of sodiumdeficient α-nayf 4 :Yb,Er particles prepared with sodium oleate (Na-OA), rare-earth oleate (RE-OA) and ammonium fluoride (NH 4 F) in a molar ratio of 1.5 : 1 : 4.5. Histograms are displayed for particles heated in the absence (left) and in the presence (right) of additional sodium oleate and ammonium fluoride in the solvent. The mean size (d 0 ) and the relative standard deviation (σ/ d 0 ) are displayed in each image. S13

14 Figure S14: X-ray powder diffraction (XRD) data of undoped β-nayf 4 particles with different mean size prepared by Ostwald-ripening of α-nayf 4 particles with different compositions. The molar ratios of sodium oleate (Na-OA), rare-earth oleate (RE-OA) and ammonium fluoride (NH 4 F) employed in the synthesis of the α-phase particles are displayed in each diffractogram (Na-OA : RE-OA : NH 4 F). Vertical lines correspond to the reference data of NaYF 4 (hexagonal β-phase, PDF-Nr ). S14

15 Figure S15: Overview TEM-images of undoped β-nayf4 particles prepared by heating α-phase particles in oleic acid/octadecene at 300 C. The molar ratio (Na-OA : RE-OA : NH4F) is given in each TEM image. S15

16 Figure S16: Size histograms of undoped β-nayf 4 particles prepared by Ostwald-ripening of α-nayf 4 particles with different compositions. The molar ratios of sodium oleate (Na-OA), rare-earth oleate (RE- OA) and ammonium fluoride (NH 4 F) used in the synthesis of the α-phase particles are displayed in each figure (Na-OA : RE-OA : NH 4 F). The mean size (d 0 ) and the relative standard deviation (σ/d 0 ) are displayed in each image. S16

17 Figure S17: Mean size of nearly monodisperse undoped β-nayf 4 particles prepared by heating α-phase particles with different compositions in oleic acid/octadecene at 300 C. The Na/RE-ratio of the α-phase particles was determined by X-ray fluorescence spectroscopy (XRF). S17