Structure and Phase Transition in (CH3NH3)3Sb2Cl9

Abstract

(CH3NH3)3Sb2Cl9 single crystals are grown which appear to be isomorphous with Cs3Sb2Cl9 crystals of β‐modification. They are characterized by the space group Pmcn with the lattice constants: a = 0.7920(5), b = 1.3334(11), and c = 1.966(2) nm. In the crystal one can distinguish the poly‐anionic (Sb2Cl9)3‐ stacks directed along the a‐axis with three crystallographically inequivalent CH3NH 3+ cations. The DSC, dielectric, and PMR studies reveal a structural phase transition at 208 K which is related to a freezing of rotational motion of CH3NH 3+ cations.

NQR and X-ray Studies of [N(CH3)4]3M2X9 and (CH3NH3)3M2X9 (M = Sb,Bi; X = Cl,Br)

“…With further decreasing temperature, all resonance lines disappeared below 215 K; there was an endothermic peak in the DTA curve at the same temperature in the heating run. This corresponds to the first-order phase transition reported at 208 K by Jakubas et al [2].…”

“…are listed in Table 1. According to the crystal structure [2], there are four terminal and two bridging chlorine atoms in the asymmetric unit. Considering the Sb-Cl bond length [5] and the bridge angles, the bridging chlorine atoms probably give the resonance lines below 8.5 MHz.…”

“…At present three types of crystal structures of the compounds with anions M 2 X| e are known. The first one consists of onedimensional double chains of polyanions like (CH 3 NH 3 ) 3 Sb 2 Cl 9 [2], the second one shows twodimensional layers of polyanions, e.g. in Cs 3 Bi 2 Br 9 , [3], and the third one is built up of isolated M 2 X| e anions as found in [N(CH 3 ) 4 ] 3 Sb 2 Br 9 [4].…”

Reconstructive Phase Transformation and Kinetics of Cs3Sb2I9by Means of Rietveld Analysis of X-Ray Diffraction and127I NQR

“…They are (1) twoTo whom correspondence should be addressed. dimensional corrugated layer of polyanions (6-8, 10, 11), (2) one-dimensional double chains of polyanions (12)(13)(14), (3) isolated bioctahedral M X\ anion (14)(15)(16), and (4) isolated unit composed of four octahedra (17). Type (4) has been reported only for Bi compounds as far as we know.…”

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…”