K₂Sn₂ZnSe₆, Na₂Ge₂ZnSe₆, and Na₂In₂GeSe₆: a new series of quaternary selenides with intriguing structural diversity and nonlinear optical properties

Abstract

Three new compounds (i.e., K2Sn2ZnSe6, Na2Ge2ZnSe6, and Na2In2GeSe6) with intriguing structural diversity and nonlinear optical properties were discovered for the first time. They crystallize in space groups P4/ncc, I4/mcm and Cc, respectively. In K2Sn2ZnSe6 and Na2Ge2ZnSe6, the [Sn(Ge)Se4] tetrahedra and [ZnSe4] tetrahedra are linked via edge-sharing to build up a 1D [Sn2ZnSe6] infinite chain separated by K(+)(Na(+)) cations along the c direction, while the structure of Na2In2GeSe6 is an interesting three-dimensional framework composed of [InSe4] and [GeSe4] tetrahedra via corner-sharing with Na(+) cations in the cavities. The experimental optical band gaps of these compounds were determined as 1.71(2) eV, 2.36(4) eV and 2.47(2) eV, respectively, according to UV-vis-NIR diffuse reflectance spectroscopy. Interestingly, in addition to the large band gap (1.80 eV for AgGaSe2, as a comparison), Na2In2GeSe6 exhibits phase-matchable nonlinear optical (NLO) properties with a powder second harmonic generation signal about 0.8 times that of AgGaS2. Moreover, Na2In2GeSe6 melts congruently at a rather low temperature of 671 °C, which suggests that bulk crystals can be easily obtained by the Bridgman-Stockbarger method. Our preliminary results indicate that Na2In2GeSe6 has promising applications in IR nonlinear optics.

Li2MnSnSe4: A New Quaternary Diamond‐Like Semiconductor with Nonlinear Optical Response and Antiferromagnetic Property

“…The lengths of the Li−Se bonds range from 2.51(10) to 2.59(3) Å, which are shorter than 2.64(3) to 2.83(3) Å in LiGaGe 2 Se 6 and 2.61(1) to 2.86(2) Å in Li 2 In 2 SiSe 6 . The Sn−Se bond lengths vary from 2.5114(4) to 2.5249(17) Å, which are consistent with those for tetrahedrally coordinated Sn in K 2 MnSnSe 4 (2.516(1) to 2.525(1) Å) and K 2 Sn 2 ZnSe 6 (2.4986(8) to 2.5672(7)) Å . As for the (Li/Mn)−Se bond lengths, they range from 2.512(3) to 2.586(8) Å, comparable to the values of Li−Se (2.5963 Å in Li 2 Se) and Mn−Se (2.3087 Å in MnSe) bond lengths.…”

“…[5c] The SnÀSe bond lengths vary from 2.5114(4) to 2.5249 (17) ,w hich are consistent with those for tetrahedrally coordinated Sn in K 2 MnSnSe 4 (2.516(1)t o2 .525(1) ) [14] and K 2 Sn 2 ZnSe 6 (2.4986(8) to 2.5672 (7)) . [15] As for the (Li/Mn)ÀSe bond lengths, they range from 2.512(3) to 2.586 (8) ,c omparable to the valueso fL i ÀSe (2.5963 in Li 2 Se) [16] and MnÀSe (2.3087 in MnSe) [17] bond lengths.…”

Li7Cd4.5Ge4Se16 and Li6.4Cd4.8Sn4Se16: Strong Nonlinear Optical Response in Quaternary Diamond‐Like Selenide Networks

“…They crystallize in the noncentrosymmetrics pace group Selected bond lengths for the title compounds are listed in Ta ble S1.F or Li 7 (17) ) [36] and K 2 Sn 2 ZnSe 6 (2.4986(8)-2.5672 (7) ). [37] For the two title compounds, the CdÀSe bond lengths vary from 2.570(2) to 2.653(3) ,w hich is in good agreement with the values of 2.360(3) to 2.900(4) in La 3 CdGaSe 7 [38] and2 .609(2) to 2.631 (2) in CsCdInSe 3 . [39] The (Li/Cd)ÀSe bond lengths range from 2.314(19) to 2.750 (12) ,w hichi sc omparable to the valueso fLi ÀSe and CdÀSe bond lengths mentioned above.…”

New cation-disordered quaternary selenides Tl2Ga2 TtSe6 (Tt=Ge, Sn)

“…The Li atoms in distorted tetrahedral coordination (Li@S 4 ) form an infinite chain parallel to the c axis by vertex-sharing. K 2 Sn 2 ZnSe 6 and Na 2 Ge 2 ZnSe 6 ( [11], Fig. 3b and c) .…”

“…The substitution of In for Ga results in a series of compounds Li 2 In 2 Si(Ge)S 6 (Se 6 ) that crystallize in a monoclinic structure, space group Cc [8,9]. Isostructural sodium-containing compounds Na 2 In 2 Si(Ge)S 6 (Se 6 ) and Na 2 CdGe 2 S 6 (Se 6 ) have also been reported [10][11][12][13]. It has been found that Na 2 Ga 2 GeS 6 crystallizes in the orthorhombic structure (space group Fdd2), while Na 2 In 2 SiS 6 and Na 2 In 2 GeS 6 have monoclinic structures (space group Cc).…”