Supporting Information

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1 Supporting Information Resonance Emission Enhancement (REE) for Narrow Band Red-Emitting A2GeF6:Mn 4+ (A=Na, K, Rb, Cs) Phosphors Synthesized via a Precipitation-Cation Exchange Route Hongzhou Lian,, Qingming Huang, Yeqing Chen,, Kai Li, Sisi Liang, Mengmeng Shang, Manman Liu, and Jun Lin*,, School of Applied Physics and Materials, Wuyi University, Jiangmen, Guangdong , P. R. China State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun , P. R. China Instrumentation Analysis and Research Center, Fuzhou University, Fuzhou, Fujian , P. R. China Synthesis and characterizations of K2MnF6 precursor 1. Synthesis of K 2 MnF 6. The K2MnF6 precursor was prepared as follow: 2.5g of powdered KHF2 (Macklin, Shanghai, China, 99.5%) was dissolved into 20mL of 40 % HF (Macklin, Shanghai, China) in a 50 ml plastic beaker, after 20min of vigor stirring, 2g powdered KMnO4 (Aladdin, Shanghai, China, A. R.) were added. 1 Agitate the liquid after immersing the beaker in an ice-bath, and then 1mL pure diethyl-ether was dropped into the mixture. After 30min of stirring, the products were collected by centrifugation, washed several times by glacial acetic acid, and were finally displaced by washing with acetone, and K2MnF6 powder was obtained after oven-dried at XRD patterns of K 2 MnF 6. The XRD patterns of K2MnF of as-prepared K2MnF6 precursor are shown in the upper part of Figure S1. All the diffraction peaks could be indexed to the space group of P63mc (JCPDS ) of hexagonal K2MnF6. All of the patterns are consistent with the corresponding JCPDS card and no impurity is observed, indicating that the obtained precursor is single hexagonal phase 1

2 with lattice constants of a=b=5.719å, and b=9.33å. 3. XPS of K 2 MnF 6. Figure S2 shows the XPS survey spectrum of the precursor. Potassium species were clearly observed at about 16.1 ( 3 p), 292 ( 2 p3/2), 378 ( 2 s) ev, and fluoride species at about 30 ( 2 s) and 685 ( 1 s) ev. Signals from manganese species can also been detected at about 50 ( 3 p, Mn 4+ ), 642 ( 2 p3/2, Mn 4+ ), and 654 ev ( 2 p1/2, Mn 4+ ). A certain amount of oxygen ( 1 s, 531 ev) and carbon ( 1 s, 284 ev) indicated in Figure S2 were probably generated by adsorbed CO2 in air. It can be seen that all of signals from manganese were indexed to Mn 4+, and there is no signal from Mn 2+ detected from Figure S2, indicating that the purity of Mn EPR of K 2 MnF 6. Figure S3 shows EPR spectrum of obtained precursor. However, the hyperfine structure of Mn 4+ couldn t be observed in the figure. The unstructured EPR signal can be attributed to the higher Mn 4+ concentrations. 2 Kreissl and Gehloff explained the broad EPR signal as owing to an inhomogeneous distribution of Mn in the substance and be ascribed to new Mn 4+ centers formed by clustered manganese ions arising from higher Mn 4+ concentrations. 2, 3 In the system of powdered K2MnF6 samples, the concentration of Mn 4+ is very high and therefore result in broad lines as shown in Figure S3. References (1) Palmer W. G. Experimental Inorganic Chemistry. The Syndics of the Cambridge University Press: London, (2) Arai T.; Adachi S. Mn-activated Na2SiF6 red and yellowish-green phosphors: A comparative study. J. Appl. Phys., 2011, 110, (3) Kreissl J.; Gehlhoff W. EPR Investigations of ZnS:Mn and ZnSe:Mn Single Crystals, Powders, Thin-Film Structures. Phys. Status Solidi A, 1984, 81,

3 Figure S1. The XRD patterns of as-prepared K2MnF6 precursor. 3

4 Figure S2. The XPS survey spectrum of the precursor K2MnF6 4

5 Figure S3. The EPR spectrum of as-prepared K2MnF6 precursor. 5

6 Figure S4. XRD patterns of Na2GeF6:xMn 4+ with different dopant starting concentration. 6

7 Figure S5. XRD patterns of K2GeF6:xMn 4+ with different dopant starting concentration. 7

8 Figure S6. XRD patterns of Rb2GeF6:xMn 4+ with different dopant concentrations. 8

9 Figure S7. Rietveld refinements of powder XRD profiles of the representative (a) Na2GeF6:0.1Mn 4+, (b) K2GeF6:0.03Mn 4+, (c) Rb2GeF6:0.008Mn 4+. 9

10 Figure S8. Three-dimensional perspective view of (a) Na2GeF6, (b) K2GeF6, and (c) Rb2GeF6. SEM images of (d) Na2GeF6:0.1Mn 4+, (e) K2GeF6:0.03Mn 4+, (f) Rb2GeF6:0.008Mn 4+, and day-light photographs of (g) Na2GeF6:0.1Mn 4+, (h) K2GeF6:0.03Mn 4+, (i) Rb2GeF6:0.008Mn 4+ 10

11 Figure S9. EPR spectra of (a) Na2GeF6:0.1Mn 4+, (b) K2GeF6:0.03Mn 4+, (c) Rb2GeF6:0.008Mn 4+, (d) Cs2GeF6:0.03Mn 4+ samples. The hyperfine sextet lines of the spectral is presented in red as inset in (d) 11

12 Figure S10. Thermogravimetric (TG, black line) and different scanning calorimetry (DSC, blue line) spectra of (a) Na2GeF6:0.1Mn 4+, (b) K2GeF6:0.03Mn 4+, (c) Rb2GeF6:0.008Mn 4+, and (d) Cs2GeF6:0.03Mn 4+ samples. 12

13 Fig S11. (a) Excitation and (b) emission spectra of Na2GeF6:xMn 4+ with different dopant starting concentration. 13

14 Figure S12. (a) Excitation and (b) emission spectra of K2GeF6:xMn 4+ with different dopant starting concentration. 14

15 Fig S13. (a) Excitation and (b) emission spectra of Rb2GeF6:xMn 4+ with different dopant starting concentration. 15

16 Fig S14. (a) Excitation and (b) emission spectra of Cs2GeF6:xMn 4+ with different dopant starting concentration. 16

17 Figure S15. Raman spectra of (a) Na2GeF6:0.1Mn 4+, (b) K2GeF6: 0.03Mn 4+, (c) Rb2GeF6:0.008Mn 4+, and (d) Cs2GeF6:0.03Mn 4+ samples. 17

18 Figure S16. Concentration-dependent luminescence decay curves of (a) Na2GeF6:xMn 4+, (b) K2GeF6:xMn 4+, (c) Rb2GeF6:xMn 4+, and (d) Cs2GeF6:xMn 4+. The calculated average lifetimes of samples under different dopant concentration are listed as inset table of each figure. 18

19 Figure S17. Emission spectra of the as-synthesized Na2GeF6:0.1Mn 4+ samples at T = RT to 300 o C. 19

20 Figure S18. Emission spectra of the as-synthesized K2GeF6:0.03Mn 4+ samples at T = RT to 300 o C. 20

21 Figure S19. Emission spectra of the as-synthesized Rb2GeF6:0.008Mn 4+ samples at T = RT to 300 o C. 21

22 Figure S20. Emission spectra of the as-synthesized Cs2GeF6:0.03Mn 4+ samples at T = RT to 300 o C. 22

23 Table S1. Detailed Crystallographic Data after Refinements of Na2GeF6:0.1Mn 4+, K2GeF6:0.03Mn 4+, Rb2GeF6:0.008Mn 4+, andcs2gef6:0.03mn 4+ Samples NGF:0.1Mn 4+ KGF:0.03Mn 4+ RGF:0.008Mn 4+ CGF:0.03Mn 4+ Space group P321 P - 3m1 P - 3m1 Fm - 3m Symmetry Rhombohedral Rhombohedral Rhombohedral Cubic a, Å b, Å c, Å α, deg β, deg γ, deg θ, deg V, Å ρ, g/cm