METAL-TO-INSULATOR TRANSITIONS IN CAVOY

A metal-to-insulator transition in CaVO(y) by varying the oxygen stoic hiometry is reported. Stoichiometric CaVO(y) (y=3.00) shows good metal lic conductivity but slight oxidation (ycongruent-to3.05) causes the s ystem to be insulating without any significant structural changes. Thi s behavior is contrary to that seen in another d(l) system LaTiO(y), w hich is a Mott insulator for y=3.00 but becomes metallic by oxidation. We suggest that, in CaVO(y), oxygen defects primarily induce addition al scattering which causes the metallic CaVO3 to be insulating rather than add extra carriers.