Quaternary selenostannates Na2−xGa2−xSn1+xSe6 and AGaSnSe4 (A=K, Rb, and Cs) through rapid cooling of melts. Kinetics versus thermodynamics in the polymorphism of AGaSnSe4

Solid-state synthesis, structural variants and transformation of three-dimensional sulfides, AGaSnS4 (A=Na, K, Rb, Cs, Tl) and Na1.263Ga1.263Sn0.737S4

“…Synthesis and single crystal X-ray structures of similar gallium selenides, a-KGaSnSe 4 , b-KGaSnSe 4 , b-RbGaSnSe 4 and b-CsGaSnSe 4 and transformations of a and b to g-modifications for potassium and rubidium compounds have been reported [9]. Similar results are obtained in the present study.…”

“…We have initiated a similar synthetic study of A/Ga/Sn/S (A ¼ alkali metal) system for new sulfides with coordinatively versatile Ga 3+ and Sn 4+ ions and, in one such attempt by flux method, isolated single crystals of KGaSnS 4 in another structural modification. This new three-dimensional structure, distinctly different from its known layered version [8], is found to be same as thermodynamically stable cubic(g) form [9,10] of AGaSnSe 4 (A ¼ K, Rb) and KInSnSe 4 . Structural variants of AMSnSe 4 (A ¼ alkali metal; M ¼ Ga, In) selenides and the effect of rate of cooling of melt on obtaining g-form were reported in the recent past.…”

“…Na + ions have distorted tetrahedral coordination, with the wide 86.6(1)-144.8(2)1 range of values of S-Na-S bond angles. A selenide analogue of 6 is Na 0.92 Ga 0.90 Sn 0.597 Se 3 that was reported [9] to crystallize in noncentrosymmetric monoclinic space group C2.…”

Supercubooctahedron (Cs6Cl)2Cs5[Ga15Ge9Se48] Exhibiting Both Cation and Anion Exchange

“…(Figure 1a) The supercubooctahedral [M 24 Se 48 ] 15À (M = Ga/Ge) cluster consists of 72 atoms, has an edge length of about 10.8 (Figure 1b), and contains 17 atoms more than the T4-[M 20 Q 35 ]c luster. [8] Each of the eight vertices is in fact an M 3 Se 9 SBU, which is linked to the neighboring vertex through sharing SeÀSe edges,a nd such an M 3 Se 9 unit is commonly regarded as aT 2 cluster without ac orner,a so bserved in Na 2Àx Ga 2Àx Sn 1 + x Se, [19] NaBa 4 Ge 3 S 10 Cl, [20] and( BMMIm) 24 [Sn 36 Ge 24 Se 132 ]. [21] In complete contrastt ot he normalT n ,P n ,o rC nclusters, [8] such as upercu- Figure S5) are comparable to the GaÀSe bond length in K 2 CuGa 3 Se 6 (2.374(1)-2.432(1) ) [22] and GeÀSe bond length in K 2 EuGeSe 5 (2.339(2)-2.408(1) ).…”

“…The [Ga 19 Ge 5 Se 48 ]s upercubooctahedron mainly determines the energy bandgap of 1,a nd Cs and Cl atoms with strongly ionic bonding nature have less influence. Models S6-S10 showed reasonable energy gaps E g of 1.5-1.7 eV (see the Supporting Information, Figure S9).…”