Tris(trimethylammonium) nonachlorodiantimonate(III), [NH(CH3)3]3[Sb2Cl9]

Excitonic Bands in the Optical Absorption Spectra of A3MX6 and A3M2X9 (A = MeNH3, Me2NH2, Me3NH, Me4N; M = Bi, Sb; X = Cl, Br, I)

“…; M = Pb, Sn; X = Cl, Br, I) are 2D (natural quantum well) systems [2][3][4][5][6]. Crystals of (M eNH3)3M2Br9 consist of 2D layers of polyanions, while crystals of (M e3N H )3Sb2Cl9 and (M e2N H 2)3Sb2Cl9 consist of 2D layers of SbCl3 connected by Cl-anions and sandwiched between alkylammonium cations (2D systems) [10,11]. Crystals of (M eNH3)3M2Cl9 are built up of 1 D double-chain polyanions and the alkyl ammonium cations surrounding them (I D sys tems) [11,12], Crystals of A 3MX6 are built up of octahedral anions MX^", while crystals of (M eNH3)3M2I9, (Me2NH 2)3Bi2I9, (M e4N )3M2Br9, and (Me4N)3M2Cl9 are built up of bioctahedral M2X9_ anions and the alkylammonium cations sur rounding them (0D systems) [11][12][13][14][15][16].…”

“…When this work was in progress, preliminary results concerning optical absorption spectra in crystals of the 0D system (MeNH3)3Bi2I9 have been reported by others [17], The compounds were prepared by methods de scribed in the literature [10][11][12][13][14][15][16][17], and identified by elemental analyses and/or Weissenberg diagrams. Thin deposits of compounds on quartz plates were prepared by methods reported previously [4][5][6][7].…”

“…exhibit strong excitonic bands in the UV-visiblenear infrared spectral region [2][3][4][5][6][7][8][9], Also, the crys tal structures of some compounds of the formula A 3MX6 and A 3M2X9 (where A = M eNH3, Me2NH2, Me3NH, Me4N; M = Bi, Sb; X = Cl, Br, I) indicate LD semiconductor behaviour [10][11][12][13][14][15][16]. Crystals of (M eNH3)3M2Br9 consist of 2D layers of polyanions, while crystals of (M e3N H )3Sb2Cl9 and (M e2N H 2)3Sb2Cl9 consist of 2D layers of SbCl3 connected by Cl-anions and sandwiched between alkylammonium cations (2D systems) [10,11].…”

AC conductivity and dielectric studies of (C5H10N)2BiCl5 compound

“…It is worthwhile to mention that a special interest has been focused on compounds with the chemical compositions R 3 M 2 X 9 and R 5 M 2 X 11 since, in several cases, the ferroelectric properties were discovered [4][5][6][7][8][9][10][11][12]. The crystal characterized by the R 2 MX 5 composition is made up either of discrete M 2 X 4À 10 moieties (two edge-sharing octahedra) or infinite dimensional chains MX 2À 5 À Á 1 (corner-sharing octahedra).…”

Pyroelectric and Dilatometric Studies on the Low Temperature Ferroelectric Phase Transition of (CH3NH3)5Bi2Br11

“…The salts with the R 3 M 2 X 9 or R 5 M 2 X 11 compositions appeared to be specially interesting since they frequently demonstrate ferroelectric properties. The crystal structure of the R 3 M 2 X 9 subclass was characterized by three types of anionic form: (1) zigzag double chains [4], (2) two-dimensional layers of the MX 6 octahedra [5], and (3) by isolated M 2 X properties are observed only for the salts built up of the layer anionic sublattice and small-sized cations, like CH 3 NH + 3 , (CH 3 ) 2 NH + 2 , and (CH 3 ) 3 NH + [7][8][9][10]. The second subclass -R 5 M 2 X 11 -was characterized exclusively by isolated M 2 X…”