Synthesis and properties of two new members of the rutile family RhO2 and PtO2

The synthesis of two new simple oxides, RhO 2 and PtO 2 , having a tetragonal rutile cell and an orthorhombically distorted rutile cell, respectively, is reported. Refined unit cell dimensions, electrical resistivity data, and thermal stability data are given. A linear plot of rutile unit cell volumes vs. effective ionic volume, (r 3 ), allows estimation of the radii of Rh 4+ and Pt 4+ .