Synthesis and Structures of Ternary Chalcogenides of Aluminum and Gallium with Stacking Faults: KMQ2 (M=Al, Ga; Q=Se, Te)

Structural, elastic, electronic and optical properties of KAl Q 2 ( Q = Se, Te): A DFT study

“…1 as a prototype for the title materials. As described elsewhere [8], the KAlQ 2 (Q ¼ Se, Te) single-crystals crystallize in the TiGaSe 2 -type crystal structure, space group C2/c (No. 15) of the monoclinic system, with 16 formula units (i.e.…”

“…Theoretical investigation of the electronic properties of the KGaQ 2 crystals has been also performed by Feng et al [1]. In contrast, there is very limited information on the physical properties of KAlQ 2 .The X-ray powder data have been reported in literature [8], showing that KAlSe 2 and KAlTe 2 are isostructural with KGaSe 2 , RbInQ 2 (Q ¼ S, Se), TlGaSe 2 , KInS 2 , KInSe 2 , and AInS 2 (A ¼ Rb, Cs) layered structures [1,10,11] . Therefore, the main objective of the present work is to explore in more detail the structural, elastic, electronic and optical properties of KAlTe 2 and KAlSe 2 crystals using first principles calculations in the framework of the density functional theory.…”

“…However, much less is known on the potassium chalcogenide materials, i.e. KMQ 2 materials, perhaps because of growth difficulties and air sensitivity of the KMQ 2 materials [8].…”

“…Kim and Hughbanks [8] synthesized and determined their single-crystal structures. Synthesis, XRD characterization and band gap measurement of the ternary gallium selenide KGaQ 2 were reported by Feng and co-workers [1].…”

Stacking disorder: the hexagonal polymorph of tris(bicyclo[2.1.1]hexeno)benzene and related examples

“…Stacking disorder manifests itself by flocks of parallel diffuse streaks of scattering density along a specific direction of reciprocal space [5]. This kind of disorder is found among inorganic substances and minerals [7][8][9][10][11], molecular crystals [12][13][14][15][16][17][18], protein crystals [19][20][21], e.g. Rubisco [22] and t-RNA [23], and even in a virus crystal [24].…”