Effect of Phase Transition on the Thermoelectric Properties of Ag₂Te

Abstract

Ag 2 Te is well-known as a silver ion conductor. In this compound, a phase transition occurs at around 420 K and silver ions jump to interstitial sites repeatedly at the point of starting the phase transition. We consider that the active movement of silver ions would have influence on the scatterings of both charge carriers and heat carrying phonons in Ag 2 Te. In order to evaluate the effect of the silver ion conduction on the thermoelectric properties of Ag 2 Te, the Seebeck coefficient, electrical resistivity, thermal conductivity and Hall coefficient of polycrystalline bulk samples of Ag 2 Te were examined in the temperature range from room temperature to 650 K. The electrical resistivity and the Seebeck coefficient dramatically changed at around 420 K due to the change of the carrier concentration before and after the phase transition. However, the carrier mobility and the lattice thermal conductivity showed no remarkable change at around the phase transition temperature. These results imply that the thermoelectric transport properties of Ag 2 Te were affected by the change of the crystal structure rather than the presence or absence of the movement of silver ions.

Thermoelectric Properties of a Single Crystalline Ag2Te Nanowire

“…The Seebeck coefficients also drastically change at 130 ∘ C, similar trend of the resistance. Such results indicate that there is a phase transition of Ag 2 Te nanowires between 120 ∘ C and 130 ∘ C, consistent with reported results [16][17][18]. The Seebeck coefficient is strongly related to the carrier density.…”

“…The Seebeck coefficient is strongly related to the carrier density. In general, the absolute Seebeck coefficient values increase with decreasing carrier density in semiconductors [19], similar with previous reports in Ag 2 Te pellets and Ag 2 Te film [17,18]. However, our results for the single Ag 2 Te nanowire show that, with increasing temperature, the absolute Seebeck coefficient values slightly decrease followed by sudden increment before phase transition, but electrical conductivity simultaneously decreases in cubic phase regime as shown in Figure 5(b).…”

Composition Modulation of Ag2Te Nanowires for Tunable Electrical and Thermal Properties

“…The same treatment for C p has been reported in several papers on Ag 2 Te. [5][6][7] Modeling with Boltzmann Transport Equations. We also model the charge carrier transport for the materials in ambipolar transport regime using the near-equilibrium Boltzmann transport equations under the relaxation time approximation.…”

Enhanced Thermoelectric Properties in Bulk Nanowire Heterostructure-Based Nanocomposites through Minority Carrier Blocking

“…The same treatment for C p has been reported in several papers on Ag 2 Te including ours. 1,[3][4][5] Carrier transport modeling. Our transport model is based on the linearized Boltzmann transport equations (BTE) under the relaxation time approximation.…”