Typical synthetic approaches for the production of oxides involve extensive heating and grinding.  We have found that the formation of pyrochlores such as Na2Ta2O6 , perovskites such as CaTa2O6 and spinels such as ZnAl2O4 can be realized by vigorously grinding hydroxide and oxide mixtures.  The formation of the desired material is enthalpically driven, but condensation only occurs upon the application of mechanical force.  This has allowed us to thoroughly study the reaction kinetics using techniques similar to quenching high-temperature reactions.  We have found that the synthesis of the pyrochlore Ca2Ta2O7 from Ca(OH)2 and Ta2O5 goes though a crystalline intermediate perovskite phase- Ca4Ta2O9.  Syntheses can take as little as one hour to go to completion. This new route will facilitate the preparation of isomorphously substituted oxides for a wide array is uses such as catalysis and lighting.

Mechanically driven condensation reactions for solid-state synthesis

243rd National Meeting (2012)

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