Broadband dielectric spectroscopy for monitoring temperature-dependent chloride ion motion in BiOCl plates

Abstract

The dielectric properties and electrical conduction mechanism of bismuth oxychloride (BiOCl) plates synthesized using chloramine-T as the chloride ion source were investigated. Thermally-activated structure rebuilding was monitored using broadband dielectric spectroscopy, which showed that the onset temperature of this process was 283 K. This rebuilding was related to the introduction of free chloride ions into [Bi2O2]2+ layers and their growth, which increased the intensity of the (101) diffraction peak. The electrical conductivity and dielectric permittivity were related to the movement of chloride ions between plates (in the low-frequency region), the interplanar motion of Cl− ions at higher frequencies, vibrations of these ions, and charge carrier hopping at frequencies above 10 kHz. The influence of the free chloride ion concentration on the electrical conductivity was also described. Structure rebuilding was associated with a lower concentration of free chloride ions, which significantly decreased the conductivity. According to the analysis, the BiOCl plate conductivity was related to the movement of Cl− ions, not electrons.

Giant Carrier Mobility in Graphene with Enhanced Shubnikov–de Haas Quantum Oscillations: Implications for Low-Power-Consumption Device Applications

“…19 In this paper, by coating a layer of a CrOCl insulator (an insulator does not result in a current shunt effect in the system of C/G, and thus, we believe that the measured electrical signals only come from the graphene) on top of monolayer graphene (C/G), as shown in Figure 1a, we demonstrate enhanced mobility in the graphene on a SiO 2 /Si substrate through a dielectric screening effect. 20,21 When we sandwiched the monolayer graphene between two layers of 2D CrOCl, the enhanced mobility can be 2 times larger than that of the C/G device. More strikingly, the observed Shubnikov−de Haas (SdH) quantum oscillation persists to a temperature of up to 100 K. Our study provides a method to improve the mobility of graphene and realize nontrivial quantum states at high temperatures for graphene-based device applications, which can effectively promote the development of low-power devices.…”