Diffuse Scattering, Short Range Order and Nanodomains in the Paraelectric SbSI

Abstract

The ferroelectric crystal structure of SbSI is built of [Sb(S,I)] ∞ chains parallel to [001] axis. In the paraelectric phase the crystal structure is disordered. Each atom is shifted from the xy mirror plane by z up or down along [001]. The Reverse Monte Carlo (RMC) simulation of diffuse scattering revealed a complicated picture of the short and medium range order. The chains are not uniform but consist of sections of different length and opposite polarity. The distribution of these sections revealed by RMC shows irregular positively or negatively polarized nanodomains. The nanodomains about 0.5 nm thick, 2.0 broad and a few nm long are elongated in the [001] direction.

Dielectric Properties of SbSI in the Temperature Range of 292-475~K

“…However, the same authors veried this information by a detailed study of diuse scattering in the crystal structure of SbSI at 320 K [8]. In [8] the average crystal structure of SbSI is described by the space group Pnam in which the [Sb(S,I)] ∞ chains are not uniform but consist of sections of dierent length and opposite polarity. These sections form nanodomains elongated in the [001] direction [8].…”

“…For example, this structure was reported for the SbSI crystals at temperatures 308 K [6] and 333 K [7]. However, the same authors veried this information by a detailed study of diuse scattering in the crystal structure of SbSI at 320 K [8]. In [8] the average crystal structure of SbSI is described by the space group Pnam in which the [Sb(S,I)] ∞ chains are not uniform but consist of sections of dierent length and opposite polarity.…”

“…In [8] the average crystal structure of SbSI is described by the space group Pnam in which the [Sb(S,I)] ∞ chains are not uniform but consist of sections of dierent length and opposite polarity. These sections form nanodomains elongated in the [001] direction [8]. Recently [9] the antiferroelectric phase transition was found by a measured capacitance change at a frequency of 1 kHz for SbSI crystals grown by the BridgmanStockbarger technique.…”

The nature of anharmonicity and phase transition in SbSBr crystal

“…We came to the conclusion that the fractional atomic displacements of all atoms up and down from the xy mirror plane in SbSBr and SbSI crystals [11] in average structure of paraelectric phase are created by strong anharmonicity of low-frequency B 1u vibration modes along the c(z)-axis. This strong anharmonicity is created by interaction between phonons.…”

“…Lukaszewicz et al [11] investigated the SbSI crystal structure in a broad temperature range. They found that in paraelectric phase the crystal structure of SbSI at 320 K is disordered.…”