Luminescence study of cerium-doped La2Hf2O7: Effects due to trivalent and tetravalent cerium and oxygen vacancies

► The luminescence exhibited by La2Hf2O7:Ce peaks at 460 nm. ► The character of each emission spectrum is temperature and atmosphere dependent. ► First principles calculations predict that Ce4+ can substitute in Hf sites. ► Although Ce3+ may be present, no emission can be attributed to Ce3+ in La sites.