Electrical Conductivity in Mixed Calcium and Barium Iron Phosphate Glasses

Abstract

The electrical properties of xCaO–(20 — x)BaO–20Fe2O3–60P2O5 glasses with x = 0, 5, 10, 15 and 20 mol% have been studied in the frequency range 400 Hz–200 kHz and over a temperature range 323–593 K. The ac conductivity as a function of temperature was divided into two domains, one where the absolute magnitude of the ac conductivity was close to the dc conductivity and another where it was larger than the dc conductivity. At the same temperature, the dc conductivity varied only slightly in glasses with different CaO and BaO content. It is concluded that the conductivity in these mixed CaO and BaO iron phosphate glasses is electronic and depends upon the Fe2+/(Fe2+ + Fe3+) ratio. In the high‐temperature region above θD/2 (where θD is the Debye temperature) the Mott model of small polaron hopping (SPH) between nearest neighbours is consistent with the conductivity data, while at low temperature (below θD) the Greaves intermediate variable‐range hopping (VRH) model is found to be appropriate. The electrical conduction of the glasses is confirmed to be non‐adiabatic SPH. Mössbauer spectral analysis indicates the presence of both Fe2+ and Fe3+ ions.

Transport properties of Ba-doped BiFeO3 multiferroic nanoparticles

“…It is clear that, the density of states N(E F ) is the order of 10 21 (eV -1 cm -3 ) [14,15]. The values of N(E F ) are listed in Table 3.…”

“…The values of N(E F ) are listed in Table 3. The N(E F ) values are reasonable for the localized states [14,15].…”

“…A strong electron-phonon interaction is considered to be responsible for the formation of small polarons [11] and the polaron hopping conduction model has been used to illustrate the semiconducting behavior. The semiconducting properties of transition metal oxide (TMO) arise from the presence of different valence states of transition metal ions [12][13][14][15][16][17].…”

Compositional effect on structural and spectroscopic properties of P2O5–SnO–MnO ternary glass system

“…Some phosphate glasses containing BaO, CaO, SnO or ZnO have been proposed as replacements for the Pb-rich glasses that show a low glass transition temperature and a high thermal expansion coefficient [8][9][10][11]. On the other hand, phosphate glasses incorporating transition metal oxides are known to be semiconducting, which promises potential applications as electrical materials [12][13][14]. The small polaron hopping occurring between multi-valenced transition metal ions was reported to be responsible for electronic conduction, but the measured conductivities were low in most phosphate glasses [12][13][14].…”

“…On the other hand, phosphate glasses incorporating transition metal oxides are known to be semiconducting, which promises potential applications as electrical materials [12][13][14]. The small polaron hopping occurring between multi-valenced transition metal ions was reported to be responsible for electronic conduction, but the measured conductivities were low in most phosphate glasses [12][13][14]. However, phosphate glass containing SnO was applied to the anode material of a Li-secondary battery [9,15].…”