Local structure and conductivity behaviour in Bi7WO13.5

Total neutron scattering analysis reveals details of cation coordination and vacancy distribution in Bi7WO13.5.</p

Bi2V1-x (Mg0.25Cu0.25Ni0.25Zn0.25) x O5.5-3x/2: A high entropy dopant BIMEVOX

A high entropy dopant approach has been used to prepare a new BIMEVOX ceramic system, Bi2V1-x(Mg0.25Cu0.25Ni0.25Zn0.25)xO5.5-3x/2. Structures were investigated using a combination of X-ray and neutron powder diffraction, with electrical characterisation by A.C. impedance spectroscopy. A γ-type phase is observed at room temperature over the compositional range 0.10 ≤ x ≤ 0.30, the upper limit of which is beyond that seen for all the single substituted systems based on these substituents, apart from BIMGVOX. No stabilisation of the fully disordered γ-phase is seen at room temperature over this compositional range, with only the incommensurately ordered γ'-phase evident below around 450 °C. Changes in defect structure are used to explain an apparent transition in the compositional variation of lattice parameters. The HE dopant approach has no detrimental effect on ionic conductivity, with values comparable to those of the single substituted systems based on the component oxides

Dopant clustering and vacancy ordering in neodymium doped ceria

Lanthanide doped cerias, show fast oxide ion conduction and have applications as electrolytes in intermediate temperature solid oxide fuel cells. Here, we examine the long- and short-range structures of Ce1−xNdxO2−x/2 (0.05 ≤ x ≤ 0.30, NDC) using reverse Monte Carlo modelling of total neutron scattering data, supported by measurements of electrical behaviour using a.c. impedance spectroscopy. Three distinct features are evident in the local structure of NDC, viz.: clustering of Nd3+ cations, preferred Nd3+-oxide ion vacancy association and oxide ion vacancy clustering with preferential alignment in the 〈100〉 direction. Interestingly, the presence of preferential dopant cation-oxide ion vacancy association is also observed at 600 °C, although diminished compared to the level at room temperature. This suggests a continued contribution of defect association enthalpy to activation energy at elevated temperatures and is reflected in similar compositional variation of high- and low-temperature activation energies

An ab initio study of oxide ion dynamics in type-II Bi3NbO7

Oxide ion dynamics in the type-II phase of Bi3NbO7have been studied using a series of DFT molecular dynamics calculations.</p

Structural and electrical behaviour in Bi14YO22.5

National Science Centre Poland for project grant numbers 2012/05/E/ ST3/02767 and 2013/09/N/ST3/0432

The double rare-earth substituted bismuth oxide system Bi3Y1-xYbxO6

National Science Centre Poland for project grant number 2012/05/E/ST3/02767 and the National Centre for Research and Development Poland for project grant number DKO/PL-TW1/6/2013

Oxide ion distribution, vacancy ordering and electrical behaviour in the Bi3NbO7-Bi3YbO6 pseudo-binary system

National Centre for Research and Development (Poland) for grant no. DKO/Pl-TW1/National Centre for Research and Development (Poland) for grant no. DKO/Pl-TW1/National Centre for Research and Development (Poland) for grant no. DKO/Pl-TW1/6