Electrochemical and Specific Heat Measurements on Tellurium-Halogen Systems

Abstract

Gibbs free energies of reaction in the systems Te-TeX4 (X = Cl, Br, I) were determined from e.m.f. measurements of solid state galvanic cells using silver halides as auxiliary electrolytes. From the temperature dependence of the e.m.f. the standard entropies and enthalpies of formation SO (298.15 K) and AHi° (298.15 K) have been calculated for oc-Tel, Tel 4 , Te 2 Br, TeBr 4 , Te 3 Cl 2 and TeCl 4 . The specific heats of oc-Tel and Te2Br were determined from 1.5 K to 300 K by adiabatic and differential scanning calorimetry.

Raman and Infrared Spectra of Tellurium Sub‐Bromide (Te2Br)

“…These structural features have been established and confirmed from X-ray [l] and Mossbauer measurements [3,4]. Physical properties of Te,Br that have been measured and reported thus far are electrical conductivity [5], specific heat, Debye temperatures, and electromotive force [2]. A value of 0.6 eV is reported in [6] for the fundamental energy gap.…”

“…From this it is concluded that the electrical conductivity of the isotypic Te2X (X = Br, I, C1) series does not depend on the species of halogen but only on the configuration of the tellurium unit cell [5]. Concerning the physical properties of Te,Br and other subhalides, it is believed that these materials are generally less anisotropic than elemental Te [2].…”

“…The crystals used in these measurements were cleaved from larger single crystals which had been prepared with a modified Bridgman technique and an excess halogen content [2]. Thin and extremely fragile plates were obtained from larger as-grown crystals after careful cleaving.…”

Unlocking Four‐electron Conversion in Tellurium Cathodes for Advanced Magnesium‐based Dual‐ion Batteries

“…Upon charging the Te electrode to 1.5 V vs. Mg/Mg 2+ , an intermediate state between the two charge plateaus of Te, characteristic 3d 3/2 and 3d 5/2 peaks of Te 2+ at 585.8 eV and 574.5 eV were detected. These two peaks imply the formation of metastable tellurium subchlorides, in which partial Te atoms in the Te chain bind with two chlorine atoms axially, like the Te 3 Cl 2 structure [46] . Additional Te 4+ peaks at 587.7 eV and 577.3 eV were also observed, which could come from the oxidation of active Te 2+ species once exposed to air [32] .…”

“…These two peaks imply the formation of metastable tellurium subchlorides, in which partial Te atoms in the Te chain bind with two chlorine atoms axially, like the Te 3 Cl 2 structure. [46] Additional Te 4 + peaks at 587.7 eV and 577.3 eV were also observed, which could come from the oxidation of active Te 2 + species once exposed to air. [32] Further charging the Te electrode to 3.1 V vs. Mg/Mg 2 + led to a significant increase in the intensity of Te 4 + peaks.…”