Phase stability and ionic conductivity in substituted La{sub 2}W{sub 2}O{sub 9}

Journal Article · Fri Feb 15 04:00:00 EST 2008 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2007.11.024· OSTI ID:21043885

Pena-Martinez, J; Ruiz-Morales, J C ^[1]

---

1. Departamento de Quimica Inorganica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez s/n, 38200-La Laguna, Tenerife (Spain)

Different substitutions, i.e. Sr{sup 2+}, Ba{sup 2+}, K{sup +}, Nb{sup 5+} and V{sup 5+}, have been performed in the triclinic {alpha}-La{sub 2}W{sub 2}O{sub 9} structure in order to stabilise the high temperature and better ionic conductor cubic {beta}-phase. This approach has been used to try to obtain a new series of ionic conductors with LAMOX-type structure without molybdenum and presumably better redox stability compared to {beta}-La{sub 2}Mo{sub 2}O{sub 9}. Nanocrystalline materials obtained by a freeze-drying precursor method at 600 deg. C exhibit mainly the {beta}-La{sub 2}W{sub 2}O{sub 9} structure, however, the triclinic {alpha}-form is stabilised as the firing temperature increases and the crystallite size grows. Only high levels of Ba{sup 2+} and V{sup 5+} substitutions retained the cubic form at room temperature after firing above 1100 deg. C. However, these phases are metastable above 700 deg. C, exhibiting an irreversible transformation to the low temperature triclinic {alpha}-phase. The synthesis, structure, phase stability, kinetic of phase transformation and electrical conductivity of these materials have been studied in the present report. - Graphical abstract: Several substitutions have been tested in order to investigate the stabilisation of the high temperature cubic {beta}-La{sub 2}W{sub 2}O{sub 9} and to obtain new ionic conductors with LAMOX structure without molybdenum composition.

• OSTI ID: 21043885
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 181; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
BARIUM IONS
CRYSTAL-PHASE TRANSFORMATIONS
CRYSTALS
ELECTRIC CONDUCTORS
IONIC CONDUCTIVITY
LANTHANUM COMPOUNDS
NANOSTRUCTURES
NIOBIUM IONS
OXIDES
PHASE STABILITY
POTASSIUM IONS
SOLID ELECTROLYTES
STRONTIUM IONS
SYNTHESIS
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
TRICLINIC LATTICES
TUNGSTEN COMPOUNDS
VANADIUM IONS