Nature of Vn+ ions in SnO2: EPR and photoluminescence studies

SnO{sub 2} and 5 at.% V doped SnO{sub 2} samples were prepared by citrate-gel method. From Raman study on vanadium doped SnO{sub 2}, the existence of phase separated V{sub 2}O{sub 5} clusters has been established. EPR study on the V doped sample clearly revealed the existence of V{sup 4+} ions, which are incorporated in SnO{sub 2} lattice and the existence of conduction electrons with g = 1.993. For vanadium doped SnO{sub 2} sample, there is a decrease in luminescence at 400 nm and an increase in activation energy of electrical conduction compared to undoped SnO{sub 2}, and this has been attributed to the decrease in oxygen vacancies brought about by the incorporation of V{sup 5+} in the SnO{sub 2} lattice.