BiFSeO 3 : An Excellent SHG Material Designed by Aliovalent. Substitution. Supporting Information for

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1 Supporting Information for BiFSeO 3 : An Excellent SHG Material Designed by Aliovalent Substitution Ming-Li Liang, a,b Chun-Li Hu, a Fang Kong a, * and Jiang-Gao Mao a, * a State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, , P. R. China b College of Chemistry, Fuzhou University, Fuzhou, , P. R. China FAX: (+86) ; kongfang@fjirsm.ac.cn; mjg@fjirsm.ac.cn 1. Preparation of BiFSeO Instruments and Property Characterizations. 3. X-ray Crystallography. 4. Theoretical calculations of BiFSeO References. S1

2 1. Preparation of BiFSeO 3. Bi 2 O 3 (99+%), SeO 2 (99.8+%) and HF(Hydrofluoric acid) ( 40%) were purchased from Shanghai Reagent Factory. Single crystals of BiFSeO 3 were synthesized by mild hydrothermal reactions of a mixture of Bi 2 O 3 (186.5 mg, 0.4 mmol), SeO 2 (221.8 mg, 2.0 mmol) and 40% solution of HF (200 µl) in 3 ml H 2 O at 220 o C for five days. Colorless brick of BiFSeO 3 crystals were collected in ca. 82% yield (based on Bi). IR data (cm -1 ): s, s, s, s, w. 2. Instruments and Property Characterizations. Thermal Analysis. Thermogravimetric analysis (TGA) was carried out with a NETZSCH STA 449C unit at a heating rate of 15 o C/min under nitrogen atmosphere. TG-MS Analysis. TG-MS analysis was carried out on pre-weighted samples in a nitrogen stream using a Netzsch STA449C-QMS403C apparatus. UV-Vis Diffuse Reflectance Spectroscopy. Optical diffuse-reflectance spectra were measured at room temperature with a PE Lambda 900 UV-vis-NIR spectrophotometer. The BaSO 4 plate was used as a standard (100 % reflectance). The absorption spectrum was calculated from reflectance spectrum using the Kubelka-Munk function: α/s = (1-R) 2 /2R, where R is the absorption coefficient, S is the scattering coefficient, which is practically wavelength-independent when the particle size is larger than 5 µm, and R is the reflectance. 1 Infrared (IR) Spectroscopy. IR spectra were recorded on a Magna 750 FT-IR spectrometer as KBr pellets in the range of cm -1. Powder X-ray Diffraction. Powder X-ray diffraction (XRD) patterns were collected on a Rigaku MiniFlex II diffractometer using Cu-Kα radiation in the angular range of 2θ = 5-85 o with a step size of 0.02 o. Energy-dispersive X-ray spectroscope. Microprobe elemental analyses for the Bi, Se and F elements were performed on a S2

3 field-emission scanning electron microscope (FESEM, JSM6700F) equipped with an energy-dispersive X-ray spectroscope (EDS, Oxford INCA). Second Harmonic Generation. Measurements of the powder frequency-doubling effect were carried out using the method reported before. 2 Measurements were carried out at 1064 and 2.05 µm laser radiation for ultraviolet, visible and infrared SHG, respectively. Sieved KDP and KTP samples ( µm) were taken as references for assuming SHG signals. The SHG effect depends intensely on the particle size, thus, the sample was ground and sieved into eight discrete ranges of particle sizes (0-25, 25-45, 45-53, 53-75, , , and µm). 3. X-ray Crystallography. The intensity data sets were collected on an Agilent Technologies SuperNova Dual Wavelength CCD diffractometer with graphite-monochromated Mo-Kα radiation (λ= Å) using ω-2θ scan technique and reduced by CrysAlisPro software. 3 The data set were corrected for Lorentz and polarization factors, as well as for absorption by the numerical method. 4a The structure was solved by direct methods and refined by a full matrix least squares fitting on F 2 by SHELX 97. 4b The refined Flack factors is -0.04(2), which is close to zero, confirming the correctness of its absolute structure. By using the program PLATON, 4c the structure was also checked for possible missing symmetry and none was found. Crystallographic data and structural refinements for the crystal are summarized in Table S1. Important bond distances are listed in Table S2. 4. Theoretical calculations of BiFSeO 3. Single-crystal structural data of compound BiFSeO 3 were used for the theoretical calculations. The electronic structures and optical properties were performed using a plane-wave basis set and pseudo-potentials within density functional theory (DFT) implemented in the total-energy code CASTEP. 5 For the exchange and correlation function, Perdew Burke Ernzerhof (PBE) in the generalized gradient approximation (GGA) was chosen. 6 The interactions between the ionic cores and the electrons were described by the norm-conserving pseudopotential. 7 The following valence-electron configurations were considered in the computation: Bi-5d 10 6s 2 6p 3, Se-4s 2 4p 4, S3

4 O-2s 2 2p 4, F-2s 2 2p 5. The number of plane waves included in the basis sets was determined by a cutoff energy of 850 ev. The numerical integration of the Brillouin zone was performed using a Monkhorst-Pack k-point sampling of The other parameters and convergent criteria were the default values of CASTEP code. The calculations of linear optical properties in terms of the complex dielectric function ε(ω) = ε 1 (ω) + iε 2 (ω) were made. The imaginary part of the dielectric function ε 2 was given in the following equation. 8 ij ε i j 8π h e pcv( k) pvc( k) ω) = ( f f ) δ ) 2 c v c v m V E [ E ( k) E ( hω] 2 ( k 2 k cv vc The f c and f v represent the Fermi distribution functions of the conduction and valence bands, (1) respectively. The term p i cv ( k) denotes the momentum matrix element transition from the energy level c of the conduction band to the level v of the valence band at a certain k point in the Brillouin zones and V is the volume of the unit cell. The m, e and ħ are the electron mass, charge and Plank's constant, respectively. The calculation of second-order NLO properties were based on length-gauge formalism within the independent-particle approximation. 9 We adopted the Chen s static formula, which has been derived by Rashkeev et al. 10 and later improved by Chen s group. 11 The static second-order NLO susceptibility can be expressed as χ αβγ = χ αβγ (VE) + χ αβγ (VH) + χ αβγ (two bands) (2) where χ αβγ (VE) and χ αβγ (VH) give the contributions to χ αβγ from virtual-electron processes and virtual-hole processes, respectively; χ αβγ (two bands) is the contribution to αβγ χ from the two-band processes. The formulas for calculating χ αβγ (VE), χ αβγ (VH), and χ αβγ (two bands) are given in Ref. 11. It's worth noting that more than 180 empty bands were involved in the calculations to ensure the convergence of SHG coefficients. In addition, DFT-GGA usually underestimates the conduction bands energies, so they were corrected by adding a scissor operator to reach the measured band gap during the optical property calculations. 5. References: (1) (a) Kubelka, P.; Munk, F. Z. Tech. Phys. 1931, 12, (b) Wendlandt, W. M.; Hecht, H. G. S4

5 Reflectance Spectroscopy; Interscience: New York, (2) Kurtz, S. W.; Perry, T. T. J. Appl. Phys. 1968, 39, (3) CrysAlisPro, Agilent Technologies, Version , (4) (a) CrystalClear version 1.3.5; Rigaku Corp., Woodlands, TX, 1999; (b) Sheldrick, G. M. SHELXTL, Crystallographic Software Package, version 5.1; Bruker-AXS: Madison, WI, 1998; (c) Spek, A. L. PLATON; Utrecht University: Utrecht, The Netherlands, (5) (a) Segall, M. D.; Lindan, P. J. D.; Probert, M. J.; Pickard, C. J.; Hasnip, P. J.; Clark, S. J.; Payne, M. C. J. Phys-Condens Mat. 2002, 14, (b) Milman, V.; Winkler, B.; White, J. A.; Pickard, C. J.; Payne, M. C.; Akhmatskaya, E. V.; Nobes, R. H. Int. J. Quantum. Chem. 2000, 77, 895. (6) Perdew, J. P.; Burke, K.; Ernzerhof, M. Phys. Rev. Lett. 1996, 77, (7) Lin, J. S.; Qteish, A.; Payne, M. C.; Heine, V. Phys. Rev. B 1993, 47, (8) Bassani, F.; Parravicini, G. P. Electronic States and Optical Transitions In Solids; Pergamon Press Ltd.: Oxford, U.K., 1975; Vol.149. (9) Aversa, C.; Sipe, J. E. Phys. Rev. B 1995, 52, (10) Rashkeev, S. N.; Lambrecht, W. R. L.; Segall, B. Phys. Rev. B 1998, 57, (11) Lin, J.; Lee, M. H.; Liu, Z. P.; Chen, C. T.; Pickard, C. J. Phys. Rev. B 1999, 60, S5

6 Table S1. Crystal data and structural refinements for BiFSeO 3. Formula BiFSeO 3 Formula w T/K 293(2) crystal system Orthorhombic space group Pca2 1 a/å (7) b/å (7) c/å (8) V/Å (6) Z 4 Dc(g.cm -3 ) µ(mo-kα) (mm -1 ) GOF on F Flack factor -0.04(2) R 1, wr 2 (I > 2σ(I)) a , R 1, wr 2 (all data) , a R 1 = Σ Fo - Fc /Σ Fo, wr 2 = {Σw[(Fo) 2 -(Fc) 2 ] 2 /Σw[(Fo) 2 ] 2 } 1/2. Table S2. Selected bond distances (Å) for BiFSeO 3. Bi(1)-F(1)# (10) Bi(1)-F(1) 2.413(12) Bi(1)-O(3) 2.253(8) Bi(1)-O(1)# (9) Bi(1)-O(2)# (11) Bi(1)-O(1)# (9) Bi(1)-O(2)# (11) Se(1)-O(3) 1.689(16) Se(1)-O(1) 1.713(9) Se(1)-O(2) 1.738(11) Symmetry transformations used to generate equivalent atoms: #1 -x+1/2, y, z+1/2; #2 x-1/2, -y+1, z; #3 -x, -y+1, z+1/2; #4 x, y-1, z; #5 x+1/2, -y+1, z. S6

7 Figure S1. Simulated and measured powder X-ray diffraction patterns of BiFSeO 3. Figure S2. Crystal structure of BiOIO 3. S7

8 Figure S3. TGA and DSC curves of BiFSeO 3 measured under N 2 atmosphere. Figure S4. TG-MS curves of BiFSeO 3. S8

9 Figure S5. Measured powder XRD pattern (black) of the residual of BiFSeO 3 compared with the simulated one (red) of BiO 1.18 F Figure S6. UV-Vis-NIR reflection spectrum of BiFSeO 3. S9

10 Figure S7. IR spectra of BiFSeO 3. Figure S8. The calculated band structure of BiFSeO 3. S10

11 Figure S9. The scissor-added partial density of states (the upper four panels) and the spectral decomposition of d 31 (the bottommost panel) for BiFSeO 3. Figure S10. The calculated frequency-dependent refractive indices of BiFSeO 3. S11