Skip to content

Research at St Andrews

Dependence of activation energy on temperature and structure in lanthanum gallates

Research output: Other contribution


J Bradley, PR Slater, T Ishihara, John Thomas Sirr Irvine

School/Research organisations


The parent phase of the lanthanum gallate series of electrolytes, LaGaO3, is orthorhombic at room temperature and rhombohedral between 250 and 1000degreesC (1-3). Our high resolution neutron powder studies on the doped phases, La0.9Sr0.1Ga0.8Mg0.2O3 and its Ba-analogue, show significant structural differences from the parent phase that have direct bearing on the ionic conduction process that can easily be understood in terms of the degree of tilting of the GaO6 octahedra. The monoclinic form at room temperature has a higher degree of distortion associated with the octahedra and undergoes phase transitions at elevated temperatures that relate to the change in activation energy for the ionic conduction obtained from AC impedance spectroscopy data. In particular the gradual alignment of the octahedra above 300 (Ba) or 500degreesC (Sr) as the cell heads toward cubic symmetry produces a slow, temperature-dependent decrease in Ea for ionic conduction as the tilting of the GaO6 is reduced, thereby facilitating the migration of the oxide ion. AC impedance studies of the doped lanthanum gallates reveal a similar activation energy dependence for the barium and strontium analogues with an activation energy of I eV below the transition to rhombohedral with a gradual decrease towards 0.6 eV at the highest temperature.



Original languageEnglish
Publication statusPublished - 2003

    Research areas


Discover related content
Find related publications, people, projects and more using interactive charts.

View graph of relations

Related by author

  1. Microwave irradiation synthesis to obtain La0.7-xPrxCa0.3MnO3 perovskites: electrical and electrochemical performance

    Ferrel-Alvarez, A. C., Domínguez-Crespo, M. A., Cong, H., Torres-Huerta, A. M., Palma-Ramírez, D. & Irvine, J. T. S., 15 Jan 2021, In: Journal of Alloys and Compounds. 851, 156882.

    Research output: Contribution to journalArticlepeer-review

  2. Graphitic-C3N4 coated floating glass beads for photocatalytic destruction of synthetic and natural organic compounds in water under UV light

    Hui, J., Pestana, C. J., Caux, M., Gunaratne, H. Q. N., Edwards, C., Robertson, P. K. J., Lawton, L. A. & Irvine, J. T. S., 15 Jan 2021, In: Journal of Photochemistry and Photobiology A: Chemistry. 405, 112935.

    Research output: Contribution to journalArticlepeer-review

  3. Activation of anion redox in P3 structure cobalt-doped sodium manganese oxide via introduction of transition metal vacancies

    Kim, E. J., Mofredj, K., Pickup, D., Chadwick, A., Irvine, J. T. S. & Armstrong, R., 1 Jan 2021, In: Journal of Power Sources. 481, 229010.

    Research output: Contribution to journalArticlepeer-review

  4. Photocatalytic removal of the cyanobacterium Microcystis aeruginosa PCC7813 and four microcystins by TiO2 coated porous glass beads with UV-LED irradiation

    Pestana, C. J., Portela Noronha, J., Hui, J., Edwards, C., Gunaratne, H. Q. N., Irvine, J. T. S., Robertson, P. K. J., Capelo-Neto, J. & Lawton, L. A., 25 Nov 2020, In: Science of the Total Environment. 745, 141154.

    Research output: Contribution to journalArticlepeer-review

  5. Perovskite oxynitride solid solutions of LaTaON2-CaTaO2N with greatly enhanced photogenerated charge separation for solar-driven overall water splitting

    Wang, Y., Kang, Y., Zhu, H., Liu, G., Irvine, J. T. S. & Xu, X., 25 Nov 2020, In: Advanced Science . Early View, 8 p., 2003343.

    Research output: Contribution to journalArticlepeer-review

ID: 279355