Reduced ferromagnetic transition temperatures in SrRu1-vO3 perovskites from Ru-site vacancies -: art. no. 014423

We show that annealing of stoichiometric SrRuO3 perovskites in high-pressure oxygen of 600 atm near 1100 degreesC produces SrRu1-vO3 compounds with vacancies on the Ru-sites. The creation of Ru vacancies rapidly suppresses the ferromagnetic ordering temperature, T-C, from 163 K to 45 K with an increase of vapproximate to0.09. Subtle structural changes that accompany the creation of Ru-site vacancies are different from the typical properties of transition metal perovskites, for which an increased formal oxidation state of the B-site cations normally leads to decreased B-O interatomic distances and contraction of the unit cell volume. The reduced charge screening caused by the Ru-vacancies offsets an expected decrease of the average interatomic distance Ru-O and rotation of the RuO6 octahedra as Sr atoms relax toward Ru-vacancies increases the observed volume.