Well-defined La2Sn2O7 with a phase-pure pyrochlore structure was produced by hydrothermal synthesis at temperatures as low as 200°C. Production of phase-pure La2Sn2O7 requires a pH above 10, and higher pH accelerates the crystallization process. The synthesis produced spherical particles of average particle size ∼0.59 μm (±0.12) and surface area ∼14.1 m2/g. SEM and TEM observation for morphologic evolution and kinetic analysis during crystallization indicated that La2Sn2O7 formation probably proceeds via a two-step reaction. First a transient dissolution-precipitation occurs. Then the primary crystallites aggregate because of their colloidal instability, and heterocoagulation with the lanthanum hydrous oxide precursor particles also occurs. The sluggish reaction rate at the later stage of reaction is characterized by an in situ transformation, where the soluble tin species is diffused through the porous La2Sn2O7 aggregates to react with entrapped lanthanum precursors.
|Number of pages||6|
|Journal||Journal of the American Ceramic Society|
|Publication status||Published - 2001 Nov|
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Materials Chemistry