Supporting Information

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1 Supporting Information Infrared SHG Materials CsM 3 Se 6 (M = Ga/Sn, In/Sn): Phase Matchability Controlled by Dipole Moment of the Asymmetric Building Unit Hua Lin, Ling Chen *, Ju-Song Yu, Hong Chen, Li-Ming Wu, *, Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing , People s Republic of China Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian , People s Republic of China chenl@bun.edu.cn, Tel: ; wlm@bnu.edu.cn, Tel: Experimental Section Syntheses. The following reactant was used as purchased and stored in a glovebox filled with purified Ar (moisture and oxygen level is less than 0.1 ppm), and all manipulations were performed inside the glovebox. Pure phases of title compounds were synthesized by solid state reaction technique. Based on a large number of explorations on the experimental conditions, including changing the annealing temperature, starting reactant and loading ratio, the optimal synthesis route is as following: the mixture of X (X = Ga or In, 5N), Sn (5N), Se (5N) and CsCl (3N) in the molar ratio of 1.3/1.775/6/2 (details see Table S1 and Figure S1, take In-member as an example) into fused-silica tubes under vacuum, annealing at 1073 K for 40 h 1

2 and then kept at this temperature for 100 h, followed by slowly cooled at 3 K/h to 473K and then turned off the furnace. The raw products were washed with distilled water and then dried with ethanol. Deep-red crystals were obtained. Analyses of these compounds with an EDX-equipped JSM6700F FESEM showed the presence of Cs, X, Sn, and Se in a ratio 1:1:2:6, but no other element (see Fig. S2). The homogeneous target products were performed by a Rigaku DMAX 2500 diffractometer with Cu-K α radiation (see Fig. S3). Title compounds were stable in air for more than serval months. Property Characterization. The solid-state optical absorption spectrum was performed at room temperature using a Perkin-Elmer Lambda 950 UV Vis spectrophotometer (see Fig. S4). The IR data were measured by a Perkin-Elmer Spectrum one FT-IR spectrophotometer in the range of µm (see Fig. S5). The thermal stability analyses were measured on a NETZSCH STA 449C simultaneous analyser (see Fig. S6 7). Powder SHG measurements were performed on a modified Kurtz-NLO system using 2.05 µm laser radiation and the particle size of the title compounds and AgGaS 2 (as a reference) ranges from µm for the measurement as described elsewhere. 1 Powder Laser Induced Damage Thresholds (LIDTs) Measurements. The single pulse measurement method was used to evaluate the powder LIDTs of polycrystalline title compounds with AgGaS 2 single crystal as the reference. 2 Each sample was sieved in the size range of µm, and packed into a plastic holder (diameter: 8 mm) with a thickness about 1 mm. After irradiated by the high-power 1064 nm laser 2

3 radiation with pulse width τ p of 8 ns, the apparent change of sample was monitored by an optical microscope. The power of laser beam was measured by a Nova II sensor with a PE50-DIF-C energy sensor, and the size of the damage spot was measured by a Vernier caliper. Single-Crystal X-ray diffraction (XRD). Single-crystal XRD at room temperature was collected on a Mercury 70 CCD diffractometer with Mo Kα radiation. The absorption correction was done, 3 and structures were solved by direct methods and refined using the SHELX-97 software. 4 The structural refinement was performed in similar method as the BaGa 2 SnSe 6 compound, 5 the difference is X (X = Ga or In) and Sn atoms were constrained to share the same crystallographic site. During the refinement, the occupancies were restricted by using EXYZ and EADP commands in SHELX with a fixed X:Sn ratio of 1:2 to keep the charge balance. The X : Sn ratio was also supported also by the EDX results. The good matching of the experimental and simulated XRD patterns together with the observed strong SHG intensity substantiated that the R3 space group was correct. The refinement data are listed in Tables S2 S4. Computational Section. Theoretical studies were performed by the DFT 6a with the generalized gradient approximation (GGA) 6b as implemented in the VASP. 6c The plane-wave basis with projector augmented wave (PAW) 6d,e potentials was used to represent the core electrons. The plane-wave cut-off energy of 600 ev was chosen for all calculations and denser κ-point grids of 0.02 Å 1 were carried out in the optical 3

4 property calculations. According to the single crystal structure refinement results, X and Sn atoms are share the 9b Wyckoff sites M with X occupancy of about 1/3, then, total 12 possible models have been designed. 7 The calculation model was built in the most energetic favourable manner. For calculating the optical properties, scissors operators were applied for title compounds and AgGaS 2 (AGS). The second-order abc nonlinear susceptibility χ ( 2ω, ω, ω ) were calculated through the so-called length-gauge formalism. 8 The calculation model and specific parameter settings as described in our previously reported paper. 1 Fig. S1 The PXRD patterns of different loading ratios Cs/In/Sn/Se = 2: x: y: 6 (3x+4y = 11) and the simulated PXRD pattern of CsInSn 2 Se 6. Star (blue) and triangle (red) indicate SnSe 2 and CsInSnSe 4 phase, 9 respectively. 4

5 Fig. S2 EDX result of (a) CsGaSn 2 Se 6 and (b) CsInSn 2 Se 6. Fig. S3 Experimental and simulated PXRD patterns of (a) CsGaSn 2 Se 6 and (b) CsInSn 2 Se 6. 5

6 Fig. S4 UV-Vis diffuse-reflectance spectrum of (a) CsGaSn 2 Se 6 and (b) CsInSn 2 Se 6. Fig. S5 Reflection spectra and FT-IR spectra of (a) CsGaSn 2 Se 6 and (b) CsInSn 2 Se 6. Fig. S6 TG (black) and DTA (blue) diagrams of (a) CsGaSn 2 Se 6 and (b) CsInSn 2 Se 6. 6

7 Fig. S7 The PXRD patterns of sample of (a) CsGaSn 2 Se 6 and (b) CsInSn 2 Se 6 heated at 873K (blue), 973K (red) and the simulated one (black). The sample heated at 873K was still single phased but decomposed at 973K. Fig. S8 Schematic representations of total 12 models of CsXSn 2 Se 6 (X = Ga, In) in which 3 X and 6 Sn atoms were randomly distributed over the 9 sites corresponding to the one Wyckoff 9b site in the R3 structure. Model-11 is the most energy favorable according to the total energy. 7

8 Fig. S9 Calculated band structure of (a) CsGaSn 2 Se 6 and (b) CsInSn 2 Se 6, the Fermi level is set at 0.0 ev. Fig. S10 Energy dependences of the real part (ε 1 ) and imaginary part (ε 2 ) of (a) CsGaSn 2 Se 6 and (b) CsInSn 2 Se 6. 8

9 Fig. S11 The calculated (a) refractive index (n), (b) absorption coefficient (α) and (c) reflectivity (R) of CsGaSn 2 Se 6 and CsInSn 2 Se 6. 9

10 Fig. S12 Calculated frequency-dependent SHG coefficients for (a) CsGaSn 2 Se 6 and (b) CsInSn 2 Se 6. Those of AgGaS 2 are shown as a reference (black line). Fig. S13 The calculated birefringence ( n) of (a) CsGaSn 2 Se 6 and (b) CsInSn 2 Se 6 and (c) AgGaS 2. 10

11 Table S1. Parallel reactions with different loading ratios [CsCl: X (X = Ga, In): Sn: Se = 2: x: y: 6, 3x+4y = 11] and phase analyses of the corresponding products. x y reaction product after treatment PXRD pattern Target phase (~ 60%) + SnSe a 2 (~ 40%) Target phase (~ 70%) + SnSe 2 (~ 30%) Target phase (~ 90%) + SnSe 2 (~ 10%) Pure phase Target phase (major) + A b (minor) Fig. S Target phase (major) + A (minor) Target phase (~ 70%) + A (~ 30%) Target phase (~ 50%) + A (~ 50%) a SnSe 2 (PDF: ). b A: CsInSnSe 4 : orthorhombic, Pnma, a = (2) Å, b = 7.907(6) Å, c = (9) Å, V = (2) Å 3, to be published work in our group. 11

12 Table S2. Crystallographic data and refinement details for CsM 3 Se 6 (M = 0.33 Ga (or In)/0.67 Sn). formula CsGaSn 2 Se 6 CsInSn 2 Se 6 fw crystal system trigonal trigonal crystal color deep-red deep-red cryst size (mm 3 ) space group R3(no.146) R3(no.146) a (Å) (8) (5) c (Å) 9.539(2) 9.688(8) V (Å 3 ) 913.9(2) 952.0(2) Z 3 3 D c (g/cm 3 ) µ (mm -1 ) GOOF on F R 1, wr 2 (I > 2σ(I)) a , , R 1, wr 2 (all data) , , largest diff. peak and hole(e/ Å 3 ) 0.476, , absolute structure parameter 0.027(16) (17) a R 1 = Σ F o - F c /Σ F o, wr 2 = [Σw(F o 2 - F c 2 ) 2 /Σw(F o 2 ) 2 ] 1/2 12

13 Table S3. Atomic coordinates and equivalent isotropic displacement parameters of CsM 3 Se 6. Atom Wyck. x y z U(eq)(Å 2 )* Occu. CsM 3 Se 6 (M = 0.33 Ga/0.67Sn) Cs 3a (6) (2) 1 M=Ga/Sn 9b (4) (4) (7) (2) 0.33/0.67 Se1 9b (6) (6) (6) (2) 1 Se2 9b (6) (6) (5) (2) 1 CsM 3 Se 6 (M = 0.33 In/0.67Sn) Cs 3a (8) (2) 1 M=In/Sn 9b (4) (5) (6) (2) 0.33/0.67 Se1 9b (7) (7) (8) (2) 1 Se2 9b (8) (7) (7) (2) 1 *U(eq) is defined as one-third of the trace of the orthogonalized Uij tensor. Table S4. Selected bond lengths (Å) of CsM 3 Se 6 (M = 0.33 Ga (or In)/0.67 Sn). CsGaSn 2 Se 6 CsInSn 2 Se 6 M Se (6) (7) M Se (8) (8) M Se (9) 2.549(2) M Se (8) (8) Cs Se (9) 3.937(2) Cs Se (6) (7) Cs Se (8) 3.884(2) Cs Se (7) (7) 13

14 Table S5. Powder laser induced damage thresholds (LIDTs) between title compounds and AgGaS 2. compounds laser energy (mj) spot area (cm 2 ) damage threshold (MW/cm 2 ) AgGaS CsGaSn 2 Se CsInSn 2 Se Table S6. Property comparison between title compounds and benchmark AgGaS 2. SHG coeff. (pm/v) a CsGaSn 2 Se 6 CsInSn 2 Se 6 AgGaS 2 d 15 = 53.3 d 15 = 63.9 d 22 = 24.5 d 22 = 31.1 d 36 = 18.2 d 11 = 45.5 d 11 = 51.8 d 33 = 27.2 d 33 = 21.7 trans. range (µm) b E g (ev) b birefringence a Powder SHG intensities c 3.5 AGS 4.0 AGS AGS LIDTs (MW/cm 2 ) c (10.0 AGS) (9.2 AGS) (AGS) a Calculated at 2050 nm. b Measured on ground polycrystalline samples. c Measured in the particle size range of µm, details see Table S5. 14

15 Table S7. Calculated dipole moment and the birefringence ( n) of uniaxial crystals of BaM 3 Q 6 (PM), CsM 3 Se 6 (PM) and CsM 9 Se 12 (NPM) compounds. Ave. Dipole Moment n Compounds and Phase Matching Behavior Building unit Dipole Moment of Each Building Unit 12 Magnitude (Debye: D) Direction (x, y, z) (at 2050 nm) M=0.67Ga/0.33Si GaS SiS ( , , ) M=0.67Ga/0.33Ge GaS GeS ( , , ) ,10 BaM 3 S 6 GaSe M=0.67Ga/0.33Si (PM) SiSe ( , , ) M=0.67Ga/0.33Ge GaSe GeSe ( , , ) M=0.67Ga/0.33Sn GaSe SnSe ( , , ) GaSe M=0.33Ga/0.67Sn This work CsM 3 Se 6 SnSe ( , , ) (PM) InSe M=0.33In/0.67Sn SnSe ( , , ) Cd1Se M1=0.56Cd1/0.44Ga1 11 CsM 9 Se 12 Ga1Se ( , , ) (NPM) Cd2Se M2=0.44Cd2/0.56Ga2 Ga2Se ( , , )

16 M3=0.33Cd3/0.67Ga3 Cd3Se Ga3Se ( , , ) M1=0.44Cd1/0.56In1 Cd1Se In1Se ( , , ) M2=0.46Cd2/0.54In2 Cd2Se In2Se ( , , ) M3=0.44Cd3/0.56In3 Cd3Se In3Se ( , , ) 16

17 3. References. [1] (a) Kurtz, S. K.; Perry, T. T. J. Appl. Phys. 1968, 39, (b) H. Lin, L. J. Zhou, L. Chen, Chem. Mater. 2012, 24, (c) H. Lin, L. Chen, L. J. Zhou, L. M. Wu, J. Am. Chem. Soc. 2013, 135, [2] M. J. Zhang, X. M. Jiang, L. J. Zhou, G. C. Guo, J. Mater. Chem. C 2013, 1, [3] Crystal Clear, version 1.3.5; Rigaku Corp.: The Woodlands, TX, [4] G. M. Sheldrick, SHELXTL, version 5.1; Bruker-AXS: Madison, WI, [5] X. S. Li, C. Li, P. F. Gong, Z. S. Lin, J. Y. Yao, Y. C. Wu, J. Mater. Chem. C 2015, 3, [6] (a) G. Kresse, J. Furthmuller, Phys. Rev. B 1996, 54, (b) J. P. Perdew, Y. Wang, Phys. Rev. B1992, 45, (c) G. Kresse, D. Joubert, Phys. Rev. B 1999, 59, (d) P. E. Blöchl, Phys. Rev. B 1994, 50, (e) P. E. Blöchl, O. Jepsen, O. K. Andersen, Phys. Rev. B 1994, 49, [7] R. Graucrespo, S. Hamad, C. R. A. Catlow, N. H. D. Leeuw, J. Phys.: Condens. Matter 2007, 19, 219. [8] (a) C. Aversa, J. E. Sipe, Phys. Rev. B 1995, 52, (b) S. N. Rashkeev, W. R. L. Lambrecht, B. Segall, Phys. Rev. B 1998, 57, [9] CsInSnSe 4 : orthorhombic, Pnma, a = (2) Å, b = 7.907(6) Å, c = (9) Å, V = (2) Å 3, the new discovery in our group. [10] W. L. Yin, K. Feng, R. He, D. J. Mei, Z. S. Lin, J. Y. Yao, Y. C. Wu, Dalton Trans., 2012, 41, [11] H. Lin, L. Chen, L. J. Zhou, L. M. Wu, J. Am. Chem. Soc., 2013, 135, [12] Calculated according to the equation µ = ner; µ is the dipole moment, n is total number of electrons, e is charge on the electron esu, R is difference (in cm) between the center of mass of the protons and electrons; 1 debye unit = esu cm. 17