Synthesis of hydrated KTaWO6 nanoparticles and Sn(ii) incorporation for visible light absorption.

The defect-pyrochlore stuctured semiconductor KTaWO6 has been prepared via hydrothermal synthesis, resulting in single-crystalline nanoparticles with adjustable crystallite size between 15 and 24 nm. With subsequent ion-exhange of K with Sn(ii) the band gap of this complex semiconductor can be reduced by 1.3 eV. We show that the ion-exchange is greatly facilitated by the incorporation of water into the crystal lattice.