Phase transitions and properties of 0D hybrid iodoantimonate(III) and iodobismuthate(III) semiconducting ferroics: [C(NH2)3]3Bi2I9 and [C(NH2)3]3Sb2I9

Abstract

• The guanidinium derivatives, [C(NH 2 ) 3 ] 3 Bi 2 I 9 (GBI) and [C(NH 2 ) 3 ] 3 Sb 2 I 9 (GSI), as the promising compounds for a possible application in photovoltaics. • Optical, dielectric and UV–Vis results of studies on GBI and GSI. • Ferroelastic properties of [C(NH 2 ) 3 ] 3 Bi 2 I 9 (GBI) and [C(NH 2 ) 3 ] 3 Sb 2 I 9 (GSI). The guanidinium derivatives [C(NH 2 ) 3 ] 3 Bi 2 I 9 (GBI) and [C(NH 2 ) 3 ] 3 Sb 2 I 9 (GSI) are promising compounds from the viewpoint of their electrooptical and semiconducting properties. In this paper we present the optical, dielectric, UV–Vis, Raman and 1 H NMR (spin-lattice relaxation time, T 1 , and second moment, M 2 ) results of studies on GBI and GSI. The temperature and frequency dependent ac conductivity of GBI and GSI has been analyzed in terms of the Jonscher relationship. The parameters for the ac conductivity have been estimated. The UV–Vis spectra have been analyzed for GBI and GSI and the respective calculations regarding the band gap have been carried out. GBI and GSI reveal the semiconducting properties in their high temperature phases ( σ ac in the range 10 –5 – 10 –7 S/m). 1 H NMR studies indicate the key role of the guanidium cation dynamics in the phase transitions mechanisms.