Physico-Chemical nanomaterials science
Dielectric properties of layered Cu0.15Fe1.7PS3 polycrystals
H. Ban, D. Gal, A. Haysak, A. Molnar
Department of the Physics of Semiconductors, Uzhhorod National University, Voloshina Str. 54, Uzhhorod, 88000, Ukraine
E-mail: alexander.molnar@uzhnu.edu.ua
Layered crystals of the Me1Me2P2S6 family are promising 2D functional materials for nanoelectronics. One of the most interesting of them is CuInP2S6 and solid solutions based on it. 
We investigated the temperature dependence of the dielectric constant of Cu0.15Fe1.7PS3 crystals in the temperature range 80-450 K and the frequency range 10÷105 Hz. At low temperatures (100-200K), the dielectric properties of samples are determined by the Maxwell-Wagner relaxation and, as indicated in [1], appear at the interfaces between crystallites and boundaries.

Fig. 1. Temperature dependence of real and imaginary part of dielectric permittivity of Cu0.15Fe1.7PS3.

In addition to these features, we discovered another anomaly of both the permittivity and dielectric losses at a temperature of 373K, which is most likely associated with the presence of water molecules in the interlayer space, as evidenced by the disappearance of this anomaly after a short-term annealing of the samples at a temperature of 400K. This phenomenon can be used to create nanoscale humidity sensors based on Cu0.15Fe1.7PS3.

1.	Dziaugys A., Macutkevic J., Svirskas S., Juskenas R., Wencka M., Banys J., Motria S.F., Vysochanskii Yu. Maxwelle-Wagner relaxation and anomalies of physical properties in Cu0.15Fe1.7PS3 mixed material // Journal of Alloys and Compounds – 2015. – 650, P. 386-392.