Импедансметрия нанокристаллитов Ag-=SUB=-2-=/SUB=-S, внедренных в нанопористые стекла

The temperature dependences of the dielectric spectra of Ag2S nanocrystallites synthesized inside the channels of nanoporous glasses NPG-17 with an average diameter of filamentous pores of 17 nm are studied. The macroscopic mechanism for the occurrence of the frequency dependence of the electrical response of a nanoporous structure NPG+Ag2S is proposed. Formation of the model of mechanism is based superionic phase transition in Ag2S nanocrystallites fixed inside the channels of nanoporous glass is discussed.

Superionic phase transition in individual silver selenide nanowires

The superionic phase transition temperature in Ag2Se nanowires is diameter dependent and suppressed to below 100 °C. An increase in charge carrier density accompanied by a decrease in mobility was observed across the superionic phase transition.

A closer look at superionic phase transition in (NH4)4H2(SeO4)3: impedance spectroscopy under pressure

The proton-conducting material (NH4)4H2(SeO4)3 is examined to check whether its conductivity spectra are sensitive to subtle changes in the crystal structure and proton dynamics caused by external pressure. The AC conductivity was measured using impedance spectroscopy, in the frequency range from 100 Hz to 1 MHz, at temperatures 260 K < T < 400 K and pressures 0.1 MPa < p < 500 MPa. On the basis of the impedance spectra, carefully analyzed at different thermodynamic conditions, the p–T phase diagram of the crystal is constructed. It is found to be linear in the pressure range of the experiment, with the pressure coefficient value dT s/dp = −0.023 K MPa−1. The hydrostatic pressure effect on proton conductivity is also presented and discussed. Measurements of the electrical conductivity versus time were performed at a selected temperature T = 352.3 K and at pressures 0.1 MPa < p < 360 MPa. At fixed thermodynamic conditions (p = 302 MPa, T = 352.3 K), the sluggish solid–solid transformation from low conducting to superionic phase was induced. It is established that the kinetics of this transformation can be described by the Avrami model with an effective Avrami index value of about 4, which corresponds to the classical value associated with the homogeneous nucleation and three-dimensional growth of a new phase.