Solvothermal syntheses, characterizations and semiconducting properties of four quaternary thioargentates Ba2AgInS4, Ba3Ag2Sn2S8, BaAg2MS4 (M = Sn, Ge)

Journal of Alloys and Compounds 815 (2020) 152413

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Solvothermal syntheses, characterizations and semiconducting properties of four quaternary thioargentates Ba2AgInS4, Ba3Ag2Sn2S8, BaAg2MS4 (M ¼ Sn, Ge) Yan Liu a, Yanhua Li a, Jie Zhao b, Renchun Zhang c, Min Ji a, Zhonglu You b, **, Yonglin An a, * a b c

Department of Chemistry, Dalian University of Technology, Dalian, 116024, China Department of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029, PR China College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, 455000, China

a r t i c l e i n f o

a b s t r a c t

Article history: Received 16 July 2019 Received in revised form 18 September 2019 Accepted 23 September 2019 Available online 23 September 2019

Four quaternary silver sulfides, Ba2AgInS4 (1), Ba3Ag2Sn2S8 (2), BaAg2MS4 (M ¼ Sn for 3; Ge for 4) have been synthesized solvothermally in the presence of excess sulfur as mineralizer. Compound 1 features a 2 2-D ∞ ½AgInS4 4 layer structure composed of AgS4/InS4 tetrahedra, in which the two metals randomly occupy one crystallographic unique position with the molar ratio of 1:1. Compound 2 possesses a 3-D [Ag2Sn2S8]6- framework which constructed by alternative arrangements between AgS4 and SnS4tetrahedra by sharing vertexes. The structures of compounds 3 and 4 are similar and exhibit 3-D anionic [Ag2MS4]2- (M ¼ Sn for 3; Ge for 4) framework composed of AgS2 layers and monomeric MS4 (M ¼ Sn, Ge) tetrahedra that pillar the above layers. Moreover, semiconducting properties (optical bandgap, photoelectric response) of the title compounds were also investigated. The results indicate that all the quaternary sulfides are narrow-gap semiconductors, and compound 3 exhibits excellent photocurrent responsive property. © 2019 Published by Elsevier B.V.

Keywords: Solvothermal method Quaternary Ag-Containing sulfides Alkaline earth metal Photocurrent response

1. Introduction Multinary sulfides have received considerable attentions due to their structural diversities and potential applications in photocatalysis [1e3], photoelectricity [4e6], ion exchange [7e9] and fast ion conductor [10]. The majority of them involve 13e15 group metals, and exhibit a large variety of structure types due to their flexible coordinations (e.g., 3, 4, 5, 6) with sulfur and the selfcondensation behaviors of the building blocks [11e13]. By the incorporation of late transition metals (Cu/Ag/Cd/Hg) into the 13e15 group metal anionic frameworks, the structural diversities can be greatly enhanced. In the last decades, a large number of quaternary sulfides constructed by late transition metals and 13e15 metals were reported, which exhibit interesting structures and fascinating properties [14e39]. Up to now, most of the reported quaternary sulfides were

* Corresponding author. ** Corresponding author.; E-mail addresses: [email protected] (Z. You), [email protected] (Y. An). https://doi.org/10.1016/j.jallcom.2019.152413 0925-8388/© 2019 Published by Elsevier B.V.

obtained by using alkali metal ions [24,32], organic amines [30,40], or transition metal complexes [36,41] as structural directing agents (SDAs). Comparing with the above SDAs, alkaline earth metal ions possess smaller size and higher charge density. Therefore, by using alkaline earth metal ions as SDAs may have totally different impact on the condensation behaviors of MSx species (M ¼ 13e15 group elements or transition metals) and should direct novel quaternary sulfides with rich structural diversities and intriguing properties [42e45]. However, the number of these quaternary sulfides containing alkaline earth metals is relatively less; meanwhile, these compounds usually obtained by high temperature solid state routes [46e49]. For example, Xia et al. prepared Ba4AgInS6 by the reaction of BaS, Ag2S and In2S3 at 850  C, which were carried out under inert gas atmosphere [47]. The previous research results indicate that the stabilities of these compounds are much better than alkali metal analogues, which is necessary for their applications [42]. In addition, quaternary alkaline earth metal sulfides also show other properties, such as semiconductor [47], photoeletrochemical properties [43] and nonlinear optical properties [46], which indicate they are a kind of outstanding multifunctional materials.

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Under extreme reaction conditions, the possibilities to access new compounds, especially metastable phases are greatly reduced. Therefore, exploring a mild synthetic route to discover new quaternary alkaline earth metal sulfides with structural diversities and intriguing properties is desirable. Hydro(solvo)thermal methods have been proven to be powerful owing to the advantages of lower synthesis temperature and simple operation [50e52]. Owing to the low solubility of transition metal Cu/Ag/Cd/Hg-sulfides, finding a suitable mineralizer with the role of increasing the solubility of insoluble reactants is the key to hydro(solvo)thermal syntheses. Our previous researches have demonstrated that excess sulfur is a feasible mineralizer in the syntheses of quaternary alkali metal sulfides [7,45,53,54]. Silver, as one of the late transition metals, attracts our attention because of its flexible coordinations by sulfur (e.g., 2, 3, 4) and the diverse linkages of polyhedra through vertexes or edges, which are conductive to obtaining quaternary Agcontaining sulfides with novel structures and fascinating properties. In this paper, four quaternary sulfides Ba2AgInS4 (1), Ba3Ag2Sn2S8 (2), BaAg2MS4 (M ¼ Sn for 3; Ge for 4) have been successfully synthesized by using excess sulfur as mineralizer under mild solvothermal conditions. Particularly, compounds 2e4 feature 3-D framework and all contain monomeric MS4 (M ¼ Sn, Ge) tetrahedra units. Although compounds 3 and 4 were synthesized by high temperature solid state method previously [42]. our results demonstrate that they also can be obtained using mild solvothermal methods. In addition, their semiconducting properties (optical bandgap, photoelectric response) have been investigated in detail. 2. Experimental section Most of the chemicals were analytical grade and were used as received without any further purification. The reactant of Ag2S was synthesized by the reaction of AgNO3 and (NH4)2S aqueous solution, and then washed with water and dried in air. 2.1. Syntheses The four quaternary compounds were synthesized by similar procedures. The reactants were sealed in a Pyrex glass tube (about 10% filling volume of the tube) at air atmosphere, and then the glass tube was placed in a stainless-steel autoclave (about 80% filling volume of water to balance the pressure), and finally heated in the oven for several days. After being cooled to ambient temperature naturally, the products were washed and then relatively pure crystals were obtained. Ba2AgInS4 (1) was synthesized by using Ag2S (9 mg), In(OH)3 (5 mg), S power (28 mg), Ba(NO3)2 (17 mg), about 150 mg 1,3propanediamine and 150 mg pyridine and then heated at 170  C for 9 days. After washing with ethanol, yellow plane crystals were obtained in 13% yield based on Ag. Ba3Ag2Sn2S8 (2) was prepared by using Ag2S (9 mg), Sn power (8 mg), S power (35 mg), Ba(OH)2 (26 mg), about 330 mg 1,3propanediamine and then heated at 170  C for 7 days. After washing with ethanol, yellow block crystals were obtained in 12% yield based on Ag. A small amount of compound 3 also exist in this experiment. BaAg2SnS4 (3) was synthesized by using AgNO3 (12 mg), Sn powder (5 mg), S powder (37 mg), Ba(OH)2$8H2O (13 mg), about 300 mg 1,3-propanediamine and 60 mg H2O and then heated at 170  C for 10 days. After washing by water and ethanol, respectively, orange red block crystals were obtained in 47% yield based on Ag. BaAg2GeS4 (4) was obtained by using AgNO3 (19 mg), Ge powder (5 mg), S powder (27 mg), Ba(OH)2$8H2O (14 mg), about

270 mg ethylenediamine and then heated at 170  C for 7 days. After washing by water and ethanol, respectively, orange block crystals were obtained in 74% yield based on Ag. 2.2. Crystal structure determination Single crystals of compounds 1e4 with suitable sizes were selected and mounted on a Bruker Smart APEX II diffractometer equipped with graphite monochromitized Mo Ka radiation (l ¼ 0.71073 Å) at room temperature [55]. All of the diffraction data were solved by direct methods [56]. The atomic positions and displacement parameters were executed in Fourier maps and refined anisotropically based on F2 using SHELXL-2017 [57]. The crystal data and structural refinement of the compounds are given in Table 1. 2.3. Characterizations The elemental analyses of the title compounds were experimented on EDS-equipped Quanta 450 scanning electronic microscope (SEM). Powder X-ray diffraction (PXRD) were measured on a Smart-Lab 9 KW instrument with Cu Ka (l ¼ 1.5418 Å) at room temperature. The data were collected in the range of 2q ¼ 10e65 and a scanning speed of 5 per minute. The optical diffuse spectra were measured at room temperature on Agilent Cary Series 5000 UVeviseNIR spectrophotometer equipped with an integration sphere diffuse reflectance attachment. Spectral data were collected with a wave length range of 200e2500 nm and BaSO4 was used as a reference. A DXR laser confocal microraman spectrometer was used to measure the unpolarized Raman scattering spectra of the title compounds. The spectrometer was equipped with a CCD detector using 532 nm radiation from a diode laser and the scanning range was from 100 to 600 cm1. The EDS analyses results of the title compounds are in agreement well with that of single crystal results (Fig. S1). The experimental PXRD patterns (Fig. S2) of compounds 1, 3 and 4 are consistent well with the simulated ones, which indicate that the three compounds are pure phases. For compound 2, there are redundant small peaks due to the generation of impurity compound 3. The same weights of sample (containing a small amount of impurity BaAg2SnS4) and pure compound BaAg2SnS4 were tested by powder XRD, and the proportion of BaAg2SnS4 in the sample can be estimated according to the intensities of the diffraction peaks. The analysis results show that the powder sample contain 92 wt% Ba3Ag2Sn2S8 (2) and 8 wt% BaAg2SnS4 (3). Samples of compound Ba3Ag2Sn2S8 (2) for UVeviseNIR diffuse reflection and Raman scattering spectra were picked out manually. 2.4. Photoelectrochemical characterization The photoelectrochemical tests were carried out on a CHI660E electrochemical workstation using a standard three-electrode system under simulated solar light illumination (300 W Xe lamp). The title compounds were grounded and coated onto ITO glasses (with an active area of 2.0 cm  0.5 cm) which employed as the working electrodes. A platinum sheet and a saturated Hg/Hg2Cl2 were used as the counter and reference electrodes, respectively, and 0.2 M Na2SO4 aqueous solution was chosen as the electrolyte. 3. Results and discussion 3.1. Syntheses In the solvothermal syntheses of quaternary sulfides, mineralizers play a crucial role in increasing the solubility of insoluble Cu/

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Table 1 Crystal data and structural refinement of the title compounds. Compound

1

2

3

4

empirical formula formula weight temperature (K) color crystal system space group

Ba2AgInS4 625.61 296(2) yellow orthorhombic Pnma

Ba3Ag2Sn2S8 1121.62 296(2) yellow cubic

BaAg2SnS4 600.01 296(2) orange red orthorhombic I222

BaAg2GeS4 553.91 296(2) yellow tetragonal

a (Å) b (Å) c (Å) a ( ) b ( ) g ( ) volume (Å3) Z Dc (g$cm3) abs coeff (mm1) F (000) q range ( ) index ranges

7.2931(10) 4.1909(6) 13.980(2) 90.0 90.0 90.0 427.29(10) 2 4.862 14.893 544 2.91 to 24.99 7  h  8 4  k  4 16  l  16 428/409 1.026 0.0417 0.0278 0.0767 1.714, 2.118

I43d 14.7132(13) 14.7132(13) 14.7132(13) 90.0 90.0 90.0 3185.1(5) 8 4.678 13.801 3920 3.39 to 24.99 17  h  16 17  k  12 16  l  17 475/463 1.064 0.0719 0.0355 0.0971 3.822, 1.728

no. of unique/observed reflections GOF on F2 Rint R1 [I > 2s(I)] uR2 (all data) Drmax, Drmin (e$Å3) P P P P R1 ¼ jjFoj - jFcjj/ jFoj, uR2 ¼ [ u(Fo2 - Fc2)2/ u(Fo2)2]1/2.

Ag/Cd/Hg-sulfides and further facilitating the formation of crystalline products. Recently, we prepared BaCu3MS4 (M ¼ In, Ga) and BaCu2MS4 (M ¼ Sn, Ge) by using excess sulfur as mineralizer. In our further study, we successfully prepared compounds 1e4. In the synthetic system, reducing organic amine can react with elemental sulfur and generate S2 under solvothermal reactions. Excess sulfur can react with isolated sulfur ion (S2) and generate polysulfide ion (S2 x ).

ðx  1ÞS þ S2 #S2 x

(1)

From the above equation, with the increase of sulfur, the con2 centration of S2 will x will grow, and the amount of isolated S þ decrease. The resulting S2 x can react with Ag to produce soluble complexes which will avoid the formation of silver sulfide under alkaline conditions. From the above discussion, the function of excess sulfur are the following two aspects: reducing the

2

6.880(7) 7.129(7) 8.122(8) 90.0 90.0 90.0 398.3(7) 2 5.003 13.762 528 3.80 to 27.44 8  h  7 9  k  9 10  l  9 463/438 1.089 0.0368 0.0285 0.0696 2.029, 1.453

I42m 6.834(3) 6.834(3) 8.041(3) 90.0 90.0 90.0 375.6(3) 2 4.898 15.271 492 3.91 to 27.38 8  h  8 6  k  8 10  l  10 237/223 1.073 0.0374 0.0239 0.0596 0.825, 1.375

concentration of S2 by the formation of S2 x ; decreasing the concentration of Agþ by generating soluble polysulfide complexes. In conclusion, using this mild method, we not only synthesized two new compounds 1 and 2 with novel structures, but also obtained compounds 3 and 4, which were prepared at high temperature previously. The experimental results demonstrate that solvothermal method has considerable advantages in synthesizing quaternary alkaline earth metal sulfides by selecting suitable mineralizer. 3.2. Crystal structures description Ba2AgInS4 (1) crystallizes in orthorhombic system with Pnma 2 space group and features a 2-D ∞ ½AgInS4 4 layer. The Ag and In atoms occupy the same crystallographic position and take tetrahedral coordination by four S atoms with the Ag/IneS bond distances ranging from 2.490(3) to 2.680(3) Å, which is in agreement

Fig. 1. (a) The ∞ ½AgInS4 4 layer viewing along from the [001] direction; (b) Crystal structure of compound 1 viewing along from the [010] direction. (color code: Ba blue, Ag/In red, S yellow). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

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Fig. 2. The coordination environments of Sn and Ag atoms in compound 2.

with the literature data [47,49]. As depicted in Fig. 1a, the AgS4/InS4 tetrahedra are interconnected by sharing vertexes and generate an 2 infinite ∞ ½AgInS4 4 layer. The Ba ions exist between the two adjacent anion layers and each Ba2þ is surrounded by seven S atoms with d(BaeS) ranging from 3.1831(18) to 3.324(3) Å. So far, only few

quaternary AgeIneS compounds have been synthesized [47,49]. For example, Ba4AgInS6 synthesized at high temperature features 1D [AgInS6]8- chain which constructed by alternate arrangement 2 between AgS4 and InS4 units, while there exists infinite ∞ ½AgInS4 4 layer composed of mixed Ag/InS4 tetrahedra in compound 1. Ba3Ag2Sn2S8 (2) crystallizes in cubic system with I43d space group and possesses a unique 3-D anionic [Ag2Sn2S8]6- framework composed of monomeric AgS4 and SnS4 tetrahedra via cornersharing of S(1) atoms with Ba2þ located in the channels. It can be observed from Fig. 2, Sn(1) adopts tetrahedral coordination with three S(1) atoms (distances 2.396(4) Å) and one S(2) atom (distance 2.368(8) Å). Ag(1) exhibits a severely distorted tetrahedral coordination with four S(1) atoms (distances 2.585(4) Å), and SeAgeS bond angles are 96.34 and 141.18 . The Ag/SneS bond lengths and angles are normal and comparable well with the literature data [7,25]. Meanwhile, two types of S atoms adopt different bridging modes: S(1) atoms adopt a m2-V shaped mode to link one Sn and one Ag, while S(2) atoms serve as unique terminal ligands. As depicted in Fig. 3a, SnS4 tetrahedra locate in the 3-fold axes of the cubic unit cell. Monomeric AgS4 tetrahedra (Fig. 3b) decorate with the above SnS4 tetrahedra via vertex-sharing of S(1) atoms to form a 3-D anionic [Ag2Sn2S8]6- framework viewing along from the [111] direction (Fig. 3c). The Ba2þ locate in the generating channels (Fig. 3d), and each Ba2þ is surrounded by eight S atoms with d(BaeS) ranging from 3.162(3) to 3.490(4) Å. It is noteworthy that the 3-D anionic [Ag2Sn2S8]6- framework of compound 3 is composed of monomeric AgS4 and SnS4. While in

Fig. 3. (a) The SnS4 tetrahedra are arranged along the [111] direction of the cubic unit cell; (b) AgS4 tetrahedron; (c) The 3-D anionic [Ag2Sn2S8]6- framework composed of AgS4 and SnS4 tetrahedra viewing along from the [111] direction; (d) Crystal structure of compound 2 viewing along from the [111] direction (color code: Ba blue, Ag green, Sn orange, S yellow). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

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Fig. 4. (a) The 2-D AgS2 layer viewing along from the [001] direction; (b) Crystal structure of compound 3 viewing along from the [010] direction. (color code: Ba blue, Ag green, Sn orange, S yellow). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

the reported quaternary silver-thiostannates, the anionic frameworks are usually formed by the polymerizations of SnS4 tetrahedra or AgSx units [26,44]. This 3-D framework constructed by interconnection of monomeric SnS4 and AgS4 units has never been observed in silver-thiostannates prior to this work. BaAg2SnS4 (3) and BaAg2GeS4 (4) were previously synthesized using high temperature solid-state reactions at 900  C by Wu et al. [42]. Compounds 3 and 4 crystallize in orthorhombic system with I222 space group and tetragonal system with I42mspace group, respectively. In the two structures, Ag atoms adopt distorted tetrahedral coordination, with the bond distances are 2.498(3) Å,

2.777(3) Å for compound 3, and 2.6003(13) Å for compound 4; with SeAgeS angles between 91.15(8) and 165.99(10) for compound 3, between 94.89(2) and 146.04(8) for compound 4, which are close to those other related Ag-containing sulfides [30,44,52]. Two of the structures are similar and composed of AgS2 layers and MS4 (M ¼ Sn, Ge) tetrahedra, so only the structure of compound 3 is detailed here. As depicted in Fig. 4, AgS4 units are jointed together via vertex-sharing and form an infinite AgS2 layer along the (110) plane, while Sn4þ is embedded in between AgS2 layers by sharing corners with AgS4 tetrahedra, and generating a 3-D anionic [Ag2SnS4]2- framework viewing along from the [010] direction. In

Fig. 5. UVeviseNIR absorption spectra of the title compounds.

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addition, the Ba ions exist inside the 3-D channel and each Ba2þ is coordinated by eight S atoms with d(BaeS) ranging from 3.283(3) to 3.339(4) Å. It is worth mentioning that compound 3 contains the equivalent channels along the [100] direction as well as in the [010] direction. As we know, MS4 (M ¼ Sn, Ge) tetrahedral units often generate diametric [M2S7]6-, [M2S6]4- and adamantine-like [M4S10]4- species by self-condensation via vertex- or edge-sharing [12,14,54,58]. In the reported quaternary sulfides, the common building units ([M2S7]6-, [M2S6]4- and [M4S10]4-) are usually found to be linked by transition metal ions [22,40,58]; while the case of AgeS layers to be linked by MS4 tetrahedra is very rare. Such a feature is also reflects in our previously reported K2Ag6Sn3S10, in which Sn4þ ions are incorporated in the AgeS layer and generate a unique cationic 2 1 2þ layer, while ∞ ½SnS3 2 single zigzag chains exist be∞ ½Ag6 SnS4  tween the above adjacent layers [44]. However, in compounds 3 and 4, AgS4 tetrahedral units form AgS2 layer by self-condensation via vertexes, and the monomeric MS4 units decorate with the AgS2 layers. From the perspective of templates, Ba2þ with high charge density and small size is different from other structural directing agents (SDAs), such as alkaline metal cations, organic amine or transition metal complex ions. Such features endow Ba2þ stabilize building units with high charge density and dramatically impact their condensation behaviors. In other words, it can suppress the selfcondensation of monomeric MS4 (M ¼ Sn, Ge) units in the presence of excess sulfur. The feature and influence of Ba2þ result in the presence of monomeric MS4 tetrahedra, which is conductive to obtaining novel structures that cannot acquire by other templates.

3.3. Optical properties The band gaps of the title compounds were estimated by converting the data of reflectance spectra to absorbance spectra by the Kubelka-Munk function [59,60].

FðRÞ ¼

K ð1  RÞ2 ¼ S 2R

(2)

In the above equation, K is absorption coefficient, S is scattering coefficient, and R is the reflectance. As shown in Fig. 5, the experimental band gaps are 1.98 eV for Ba2AgInS4 (1), 2.02 eV for Ba3Ag2Sn2S8 (2), 1.88 eV for BaAg2SnS4 (3) and 2.12 eV for BaAg2GeS4 (4), respectively. These experimental values indicate that the title quaternary sulfides belong to semiconductors. The Raman scattering spectra of compounds 1e4 are shown in Fig. 6. For compound 1 (Fig. 6a), the obvious resonances at 324.5 and 332 cm1 can be assigned to the IneS vibrations [31]. For compound 2 (Fig. 6b), the symmetric SneS bridging vibration is located at 337 cm1, and the signal at 180 cm1 probably due to the SnS2 wagging and twisting modes, but the detailed assignment in this region is quite ambiguous [61,62]. For compound 3 (Fig. 6c), the distinct resonances at 342 cm1 is caused by SneS bridging vibrations [61]. In addition, the resonances at 220 and 215 cm1 can be assigned to the AgeS vibrations for compounds 1 and 3, respectively [58]. For compound 4 (Fig. 6d), the obvious resonances at 372, 400 and 418 cm1 can be attributed to the characteristic stretching of GeeS bond [63]. From the perspective of characteristic Raman scattering peaks of the same main group, the intensive peak towards to the short wavelength with the increase of atomic number

Fig. 6. Raman spectra of the title compounds.

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Fig. 7. Photocurrent responses of 1 and 3 under simulated solar light illumination.

(from GeeS 372 cm1 to SneS 342/341 cm1). 3.4. Photoelectrochemical properties The photoelectrochemical experiments were performed to further investigate the separation efficiency of charge carrier pairs of the compounds. Fig. 7 shows the photocurrent-time (i-t) curves of compounds 1 and 3 in several on-off cycles under simulated solar light illumination, and the photocurrent responses of 2 and 4 were close to compound 1. The repeatable anodic photocurrent responses indicate that they are all typical n-type (electron conductive) semiconductors. It is notable that 3 exhibits stronger transient photocurrent response which is about 50 times larger than that of 1. In addition, compound 3 reached a stable state faster than 1 when the light was switched on. The results indicate that under simulated solar light illumination, 3 possesses higher transfer efficiency of photogenerated electrons and separation efficiency of photogenerated electron-hole pairs than 1, which may be related to the smaller band gap (1.98 eV) of 3 [64]. The interesting photoelectric responsive properties of compound 3 under simulated solar light illumination make it promising as a semiconducting material in potential applications of photoelectric devices [6]. 4. Conclusion In conclusion, four quaternary silver sulfides, Ba2AgInS4 (1), Ba3Ag2Sn2S8 (2), BaAg2MS4 (M ¼ Sn, for 3; Ge for 4), were synthesized solvothermally in the presence of excess sulfur as mineralizer. Particularly, compounds 2e4 feature 3-D framework and there exist monomeric MS4 (M ¼ Sn, Ge) units, which is uncommon in the quaternary analog sulfides. This is mainly because Ba2þ with high charge density and small size can suppress the selfcondensation of monomeric MS4 (M ¼ Sn, Ge) units in the presence of excess sulfur, which is conductive to directing novel structures that cannot obtain by other templates. Moreover, the investigation results of semiconducting properties indicate that all the quaternary sulfides are semiconductors, and compound 3 exhibits excellent photocurrent responsive property. The experimental results suggest that using excess sulfur as mineralizer provides a mild strategy on synthesizing more quaternary sulfides with novel structures. Accession codes CCDC numbers 1899696 (Ba2AgInS4), 1899695 (Ba3Ag2Sn2S8), 1935364 (BaAg2SnS4) and 1935365 (BaAg2GeS4) contain the

supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/ cif, or by emailing data_ [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: þ44 1223 336033. Acknowledgment This work was supported by the National Natural Science Foundation of China (Grant No. 21573016, 21171028, 21770643). Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.jallcom.2019.152413. References [1] N. Zheng, X. Bu, H. Vu, P. Feng, Open-framework chalcogenides as visible-light photocatalysts for hydrogen generation from water, Angew. Chem. Int. Ed. 44 (2005) 5299e5303. [2] Z. Zhang, J. Zhang, T. Wu, X. Bu, P. Feng, Three-dimensional open framework built from Cu-S icosahedral clusters and its photocatalytic property, J. Am. Chem. Soc. 130 (2008) 15238e15239. [3] C.-Y. Yue, X.-W. Lei, R.-Q. Liu, H.-P. Zhang, X.-R. Zhai, W.-P. Li, M. Zhou, Z.F. Zhao, Y.-X. Ma, Y.-D. Yang, Syntheses, crystal structures, and photocatalytic properties of a series of mercury thioantimonates directed by transition metal complexes, Cryst. Growth Des. 14 (2014) 2411e2421. [4] W.-W. Xiong, J. Miao, P.-Z. Li, Y. Zhao, B. Liu, Q. Zhang, [enH][Cu2AgSnS4]: a quaternary layered sulfide based on Cu-Ag-Sn-S composition, CrystEngComm 16 (2014) 5989e5992. [5] Q. Zhang, Y. Liu, X. Bu, T. Wu, P. Feng, A Rare (3, 4)-Connected chalcogenide superlattice and its photoelectric effect, Angew. Chem. Int. Ed. 47 (2008) 113e116. [6] T. Wu, Q. Zhang, Y. Hou, L. Wang, C. Mao, S.-T. Zheng, X. Bu, P. Feng, Monocopper doping in Cd-In-S supertetrahedral nanocluster via two-step strategy and enhanced photoelectric response, J. Am. Chem. Soc. 135 (2013) 10250e10253. [7] R.-C. Zhang, H.-G. Yao, S.-H. Ji, M.-C. Liu, M. Ji, Y.-L. An, (H2en)2Cu8Sn3S12: a trigonal CuS3-based open-framework sulfide with interesting ion-exchange properties, Chem. Commun. 46 (2010) 4550e4552. [8] R.-C. Zhang, J.-C. Zhang, Z. Cao, J.-J. Wang, S.-S. Liang, H.-J. Cong, H.-J. Wang, D.J. Zhang, Y.-L. An, Unusual flexibility of microporous sulfides during ion exchange, Inorg. Chem. 57 (2018) 13128e13136. [9] M.L. Feng, D.N. Kong, Z.L. Xie, X.Y. Huang, Three-Dimensional chiral microporous germanium antimony sulfide with ion-exchange properties, Angew. Chem. Int. Ed. 47 (2008) 8623e8626. [10] N. Zheng, X. Bu, P. Feng, Synthetic design of crystalline inorganic chalcogenides exhibiting fast-ion conductivity, Nature 426 (2003) 428e432. [11] B. Krebs, Thio- and seleno- compounds of main group elements-novel inorganic oligomers and polymers, Angew. Chem. Int. Ed. 22 (1983) 113e134. [12] W.S. Sheldrick, M. Wachhold, Chalcogenidometalates of the heavier Group 14 and 15 elements, Coord. Chem. Rev. 176 (1998) 211e322. [13] J. Zhou, Synthesis of heterometallic chalcogenides containing lanthanide and group 13-15 metal elements, Coord. Chem. Rev. 315 (2016) 112e134.

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Y. Liu et al. / Journal of Alloys and Compounds 815 (2020) 152413

[14] J.H. Liao, M.G. Kanatzidis, Quaternary Rb2Cu2SnS4, A2Cu2Sn2S6 (A ¼ Na, K, Rb, Cs), A2Cu2Sn2Se6 (A ¼ K, Rb), K2Au2SnS4, and K2Au2Sn2S6. Syntheses, structures, and properties of new solid-state chalcogenides based on tetrahedral [SnS4]4 units, Chem. Mater. 5 (1993) 1561e1569. [15] X. Zhang, Q. Wang, Z. Ma, J. He, Z. Wang, C. Zheng, J. Lin, F. Huang, Synthesis, structure, multiband optical, and electrical conductive properties of a 3D open cubic framework based on [Cu8Sn6S24]z clusters, Inorg. Chem. 54 (2015) 5301e5308. [16] J.E. Jerome, P.T. Wood, W.T. Pennington, J.W. Kolis, Synthesis of new lowdimensional quaternary compounds, KCu2AsS3 and KCu4AsS4, in supercritical amine solvent. Alkali metal derivatives of sulfosalts, Inorg. Chem. 33 (1994) 1733e1734. [17] Y. Shen, C. Liu, P. Hou, M. Zhi, C. Zhou, W. Chai, J.-W. Cheng, Y. Liu, Q. Zhang, Preparation of porous three-dimensional quaternary thioantimonates(III) ACuSb2S4 (A ¼ Rb, Cs) through a surfactant-thermal method, Chem. Asian J. 10 (2015) 2604e2608. [18] Y. Shen, C. Liu, P. Hou, M. Zhi, C. Zhou, W. Chai, Q. Zhang, Y. Liu, Facile surfactant-thermal syntheses and characterization of quaternary copper thioantimonates(III) ACu2SbS3 (A ¼ K, Rb, Cs), J. Alloy. Compd 660 (2016) 171e177. [19] R. Wang, X. Zhang, J. He, C. Zheng, J. Lin, F. Huang, Synthesis, crystal structure, electronic structure, and photoelectric response properties of KCu2SbS3, Dalton Trans. 45 (2016) 3473e3479. [20] H.B. Luo, L.T. Ren, W.H. Ning, S.X. Liu, J.L. Liu, X.M. Ren, Robust crystalline hybrid solid with multiple channels showing high anhydrous proton conductivity and a wide performance temperature range, Adv. Mater. 28 (2016) 1663e1667. [21] D. Zhang, G. Li, Y. Peng, L. Li, Synthesis of a ternary thiostannate with 3D channel decorated by hydronium for high proton conductivity, Inorg. Chem. 56 (2016). [22] Y. An, M. Ji, M. Baiyin, X. Liu, C. Jia, D. Wang, A solvothermal synthesis and the structure of K4Ag2Sn3S9$2KOH, Inorg. Chem. 42 (2003) 4248e4249. [23] Y. An, L. Ye, M. Ji, X. Liu, B. Menghe, C. Jia, A solvothermal synthesis and characterization of a new open-framework K4Ag2Ge3S9$H2O, J. Solid State Chem. 177 (2004) 2506e2510. [24] H.-G. Yao, M. Ji, S.-H. Ji, R.-C. Zhang, Y.-L. An, G.-l. Ning, Solvothermal syntheses of two novel layered quaternary silver-antimony (III) sulfides with different strategies, Cryst. Growth Des. 9 (2009) 3821e3824. [25] H.-G. Yao, P. Zhou, S.-H. Ji, R.-C. Zhang, M. Ji, Y.-L. An, G.-L. Ning, Syntheses and characterization of a series of silver-thioantimonates (III) and thioarsenates (III) containing two types of silver-sulfur chains, Inorg. Chem. 49 (2009) 1186e1190. [26] B. Zhang, J. Li, C.-F. Du, M.-L. Feng, X.-Y. Huang, [CH3NH3]2Ag4SnIV2SnIIS8: an open-framework mixed-valent chalcogenidostannate, Inorg. Chem. 55 (2016) 10855e10858. [27] M.G. Kanatzidis, J.-H. Chou, Isolation of b-Ag3AsSe3, (Me3NH)[Ag3As2Se5], K5Ag2As3Se9, and KAg3As2S5: novel solid state silver Thio- and selenoarsenates from solvento-thermal synthesis, J. Solid State Chem. 127 (1996) 186e201. [28] P.T. Wood, G.L. Schimek, J.W. Kolis, Synthesis and characterization of novel one-dimensional phases from supercritical Ammonia: Cs3Ag2Sb3S8, a- and bCs2AgSbS4, and Cs2AgAsS4, Chem. Mater. 8 (1996) 721e726. [29] L. Nie, G. Liu, J. Xie, T.-T. Lim, G.S. Armatas, R. Xu, Q. Zhang, Syntheses, crystal structures, and photocatalytic properties of two ammonium-directed Ag-Sb-S complexes, Inorg. Chem. Front. 4 (2017) 954e959. [30] P. Vaqueiro, A.M. Chippindale, A.R. Cowley, A.V. Powell, Templated synthesis of the novel layered silver-antimony sulfides [H3NCH2CH2NH2][Ag2SbS3] and [H3NCH2CH2NH2]2[Ag5Sb3S8], Inorg. Chem. 42 (2003) 7846e7851. [31] H. Li, C.D. Malliakas, Z. Liu, J.A. Peters, H. Jin, C.D. Morris, L. Zhao, B.W. Wessels, A.J. Freeman, M.G. Kanatzidis, CsHgInS3: a New quaternary semiconductor for g-ray detection, Chem. Mater. 24 (2012) 4434e4441. [32] J.H. Liao, G.M. Marking, K.F. Hsu, Y. Matsushita, M.D. Ewbank, R. Borwick, P. Cunningham, M.J. Rosker, M.G. Kanatzidis, А- and b-A2Hg3M2S8 (A ¼ K, Rb; M ¼ Ge, Sn): polar quaternary chalcogenides with strong nonlinear optical response, J. Am. Chem. Soc. 125 (2003) 9484e9493. [33] C.D. Morris, H. Li, H. Jin, C.D. Malliakas, J.A. Peters, P.N. Trikalitis, A.J. Freeman, B.W. Wessels, M.G. Kanatzidis, Cs2MIIMIV 3 Q8 (Q ¼ S, Se, Te): an extensive family of layered semiconductors with diverse band gaps, Chem. Mater. 25 (2013) 3344e3356. [34] K. Wu, Z. Yang, S. Pan, Na2Hg3M2S8 (M ¼ Si, Ge, and Sn): new infrared nonlinear optical materials with strong second harmonic generation effects and high laser-damage thresholds, Chem. Mater. 28 (2016) 2795e2801. [35] K. Wu, Z. Yang, S. Pan, The first quaternary diamond-like semiconductor with 10-membered LiS4 rings exhibiting excellent nonlinear optical performances, Chem. Commun. 53 (2017) 3010e3013. [36] K.-Y. Wang, L.-J. Zhou, M.-L. Feng, X.-Y. Huang, Assembly of novel organicdecorated quaternary TM-Hg-Sb-Q compounds (TM ¼ Mn, Fe, Co; Q ¼ S, Se) by the combination of three types of metal coordination geometries, Dalton Trans. 41 (2012) 6689e6695. [37] J.A. Brant, D.J. Clark, Y.S. Kim, J.I. Jang, J.-H. Zhang, J.A. Aitken, Li2CdGeS4, a diamond-like semiconductor with strong second-order optical nonlinearity in the infrared and exceptional laser damage threshold, Chem. Mater. 26 (2014)

3045e3048. [38] G.-m. Li, Q. Liu, K. Wu, Z.-h. Yang, S.-l. Pan, Na2CdGe2Q6 (Q ¼ S, Se): two metalmixed chalcogenides with phase-matching abilities and large secondharmonic generation responses, Dalton Trans. 46 (2017) 2778e2784. [39] X. Zhang, N. Yi, R. Hoffmann, C. Zheng, J. Lin, F. Huang, Semiconductive K2MSbS3(SH) (M ¼ Zn, Cd) featuring one-dimensional - chains, Inorg. Chem. 55 (2016) 9742e9747. [40] B. Zhang, M.-L. Feng, J. Li, Q.-Q. Hu, X.-H. Qi, X.-Y. Huang, Syntheses, crystal structures, and optical and photocatalytic properties of four small-aminemolecule-directed M-Sn-Q (M ¼ Zn, Ag; Q ¼ S, Se) compounds, Cryst. Growth Des. 17 (2017) 1235e1244. [41] G.L. Schimek, J.W. Kolis, G.J. Long, Metal hexaammine as a bulky cation: structural and property studies of [M(NH₃)₆]Cu₈Sb₃S₁₃ (M ¼ Mn, Fe, Ni) and [Fe(NH₃)₆]AgES₄ (E ¼ As, Sb), Chem. Mater. 9 (1997) 2776e2785. [42] H. Chen, P.-F. Liu, B.-X. Li, H. Lin, L.-M. Wu, X.-T. Wu, Experimental and theoretical studies on the NLO properties of two quaternary noncentrosymmetric chalcogenides: BaAg2GeS4 and BaAg2SnS4, Dalton Trans. 47 (2018) 429e437. [43] C. Liu, P. Hou, W. Chai, J. Tian, X. Zheng, Y. Shen, M. Zhi, C. Zhou, Y. Liu, Hydrazine-hydrothermal syntheses, characterizations and photoelectrochemical properties of two quaternary chalcogenidoantimonates(III) BaCuSbQ3 (Q ¼ S, Se), J. Alloy. Compd 679 (2016) 420e425. [44] M. Baiyin, Y.L. An, X. Liu, M. Ji, C.Y. Jia, G.L. Ning, K2Ag6Sn3S10: a quaternary 1 sulfide composed of silver sulfide layers pillared by zigzag chains∞ ½SnS3 2 , Inorg. Chem. 43 (2004) 3764e3765. [45] C. Zhang, M. Ji, S.-H. Ji, Y.-L. An, Mild solvothermal syntheses and characterization of layered copper thioantimonates (III) and thioarsenate (III), Inorg. Chem. 53 (2014) 4856e4860. [46] S.-M. Kuo, Y.-M. Chang, I. Chung, J.-I. Jang, B.-H. Her, S.-H. Yang, J.B. Ketterson, M.G. Kanatzidis, K.-F. Hsu, New metal chalcogenides Ba4CuGa5Q12 (Q ¼ S, Se) displaying strong infrared nonlinear optical response, Chem. Mater. 25 (2013) 2427e2433. [47] X.W. Lei, M. Yang, S.Q. Xia, X.C. Liu, M.Y. Pan, X. Li, X.T. Tao, Synthesis, structure and bonding, optical properties of Ba4MTrQ6 (M ¼ Cu, Ag; Tr ¼ Ga, in; Q ¼ S, Se), Chem. Asian J. 9 (2014) 1123e1131. [48] H. Lin, H. Chen, Y.-J. Zheng, Y.-K. Chen, J.-S. Yu, L.-M. Wu, Ba5Cu8In2S12: a quaternary semiconductor with a unique 3D copper-rich framework and ultralow thermal conductivity, Chem. Commun. 53 (2017) 2590e2593. [49] W. Yin, K. Feng, D. Mei, J. Yao, P. Fu, Y. Wu, Ba2AgInS4 and Ba4MGa5Se12 (M ¼ Ag, Li): syntheses, structures, and optical properties, Dalton Trans. 41 (2012) 2272e2276. [50] W.S. Sheldrick, M. Wachhold, Solventothermal synthesis of solid-state chalcogenidometalates, Angew. Chem. Int. Ed. 36 (1997) 206e224. [51] J. Li, Z. Chen, R.-J. Wang, D.M. Proserpio, Low temperature route towards new materials: solvothermal synthesis of metal chalcogenides in ethylenediamine, Coord. Chem. Rev. 190 (1999) 707e735. [52] C. Liu, Y. Shen, P. Hou, M. Zhi, C. Zhou, W. Chai, J.-W. Cheng, Y. Liu, HydrazineHydrothermal synthesis and characterization of the two new quaternary thioantimonates(III) BaAgSbS3 and BaAgSbS3$H2O, Inorg. Chem. 54 (2015) 8931e8936. [53] R.-C. Zhang, H.-G. Yao, S.-H. Ji, M.-C. Liu, M. Ji, Y.-L. An, Copper-rich framework sulfides: a4Cu8Ge3S12 (A ¼ K, Rb) with cubic perovskite structure, Inorg. Chem. 49 (2010) 6372e6374. [54] C. Zhang, K.-N. Wang, M. Ji, Y.-L. An, Mild solvothermal syntheses of thioargentates A-Ag-S (A ¼ K, Rb, Cs) and A-Ag-Ge-S (A ¼ Na, Rb): crucial role of excess sulfur, Inorg. Chem. 52 (2013) 12367e12371. [55] C. Clear, Rigaku Corp, The Woodlands, TX, 1999, version 1.3. 5. [56] G.M. Sheldrick, Crystal structure refinement with SHELXL, Acta Crystallogr. Sect. C Cryst. Struct. Commun. 71 (2015) 3e8. € ttingen, Ger[57] G. Sheldrick, SHELXS-2017 and SHELXL-2017, University of Go many, 2017. [58] C.L. Bowes, W.U. Huynh, S.J. Kirkby, A. Malek, G.A. Ozin, S. Petrov, A. Mariusz Twardowski, D. Young, R.L.B., R. Broach, Dimetal linked open Frameworks: [(CH3)4N]2(Ag2,Cu2)Ge4S10, Chem. Mater. 8 (1996) 2147e2152. [59] E. Simmons, Diffuse reflectance spectroscopy: a comparison of the theories, Appl. optics 14 (1975) 1380e1386. [60] C. Aydın, M.A. El-Sadek, K. Zheng, I. Yahia, F. Yakuphanoglu, Synthesis, diffused reflectance and electrical properties of nanocrystalline Fe-doped ZnO via sol-gel calcination technique, Opt. Laser. Technol. 48 (2013) 447e452. €ther, W. Bensch, Two new copper thiostannates synthesised [61] N. Pienack, C. Na under solvothermal conditions: crystal structures, spectroscopic and thermal properties of (DBUH) CuSnS3 and (1, 4-dabH2)Cu2SnS4, Solid State Sci. 9 (2007) 100e107. [62] N. Pienack, C. N€ ather, W. Bensch, Solvothermal syntheses of two new thiostannates and an in-situ energy dispersive X-ray scattering study of their formation, Eur. J. Inorg. Chem. 7 (2009) 937e946. [63] L. Nian, J. Huang, K. Wu, Z. Su, Z. Yang, S. Pan, BaCu2MIVQ4 (MIV ¼ Si, Ge, and Sn; Q ¼ S, Se): synthesis, crystal structures, optical performances and theoretical calculations, RSC Adv. 7 (2017) 29378e29385. [64] H. Yang, L. Wang, D. Hu, J. Lin, L. Luo, H. Wang, T. Wu, A novel copper-rich open-framework chalcogenide constructed from octahedral Cu4Se6 and icosahedral Cu 8Se13 nanoclusters, Chem. Commun. 52 (2016) 4140e4143.