Characterisation of structure and conductivity of BaTi0.5Sc 0.5O3 - δ
Artikel i vetenskaplig tidskrift, 2014

BaTi0.5Sc0.5O3 - δ was prepared via solid state reaction route and final sintering at 1550 C. High resolution X-ray powder diffraction on the as-prepared material reveals a cubic perovskite structure with a unit cell parameter, a = 4.1343(1) Å. Thermogravimetric analysis revealed the presence of significant levels of protons in the as-prepared material and 74% of the theoretically achievable protonation through filling of oxide ion vacancies was attained on exposure to a humid environment at 185 C. Infrared spectroscopy revealed a broad OH stretching band confirming the presence of OHO • defects. Electrical conductivity was measured with variable frequency AC impedance methods in oxygen, argon, and hydrogen under dry, hydrated (H2O) and heavy water (D2O) conditions. In the temperature range of 150-550 C in a wet gas atmosphere the conductivity is significantly higher than that observed for dry conditions, indicating that protons are the dominant charge carriers. Conductivity is also found to be higher in dry oxygen in comparison with dry argon over the whole temperature range of 150-1000 C, characteristic of contribution from p-type charge carriers under oxidising atmospheres. At 550 C the proton conductivity was estimated to be 2.89 × 10- 4 S cm- 1 in wet Ar. Fitting of conductivity data provides a hydration enthalpy change (ΔH hydr 0) of - 100 ± 5 kJ/mol and hydration entropy change (ΔShydr 0) of - 160 ± 10 J/mol K.

BaTiO3

Perovskite

Hydration

Proton conductivity

X-ray diffraction

Barium titanate

Författare

Seikh Mohammad Habibur Rahman

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Istaq Ahmed

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

R. Haugsrud

Universitetet i Oslo

Sten Eriksson

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Christopher Knee

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Solid State Ionics

0167-2738 (ISSN)

Vol. 255 140-146

Drivkrafter

Hållbar utveckling

Ämneskategorier

Materialteknik

Fysik

Kemiteknik

Kemi

Styrkeområden

Building Futures

Energi

Materialvetenskap

DOI

10.1016/j.ssi.2013.12.010