Oxide-ion conductivity of bismuth aluminates

Thermal expansion of mullite-type Bi2Al4O9: A study by X-ray diffraction, vibrational spectroscopy and density functional theory

“…The electronic band gap of Bi 2 Al 4 O 9 is about 4.3(1) eV as calculated by means of CRYSTAL09 at 0 K and 0 GPa [10], categorizes this compound as a wide band gap semiconductor. The set point of the ionic conductivity was reported to occur at 1073 K [3]. Therefore, the thermal expansion excludes any electronic as well as ionic contribution, and can be explained purely from the lattice vibrational internal energy.…”

“…A slight drop down of the anharmonicity in particular for high frequency modes above 1000 K is noticeable. Since 1073 K is the set point of the ionic conductivity [3], it may be associated with the ionic mobility of Bi-atoms. The low frequency modes require lower damping factors than those of high frequency modes ( Table 6), indicating that the lighter elements oxygen and aluminum mostly contribute to the thermal anharmonicity to the crystal.…”

“…Whereas most of the solid oxide fuel cells function at high temperatures ( 41000 1C) the bismuth containing oxides can better serve at low temperatures. Bi 2 Al 4 O 9 has been shown to have an intrinsic conductivity of about 10 À 2 Ω/cm at 800 1C, which is largely, but not completely, ionic [3]. The high conductivity claimed for Bi 1.8 Sr 0.2 Al 4 O 9 À δ at high temperature (1073 K) [4] was explained in terms of impurities of Bi 2 O 3 produced at elevated temperatures [5,6].…”

Improved dielectric properties of bismuth-doped LaAlO3

“…4 Bismuth-doped LAO was previously studied only as a potential oxide-ion conductor for solidoxide fuel cells as it was hoped that this material would combine the ionic conductivity of bismuth oxide, Bi 2 O 3 , with the thermal stability of LAO. 20 In this work, we have studied the effects of the substitution of bismuth for lanthanum on the dielectric properties of LAO, as we expected that the high polarizability of the Bi 3+ ion due to the lone electron pair would enhance the dielectric properties of LAO.…”

Single‐crystal growth and characterization of mullite‐type orthorhombic Bi2M4O9 (M = Al3+, Ga3+, Fe3+)

“…This is due to the fact that these compounds may display high ion electrical conductivity. Bloom et al [1] were among the first to quote the favorable oxygen ion conductivity of bismuth aluminates. Zha et al [2] found the conductivity of Sr…”