Structural and photoluminescence study of Er–Yb codoped nanocrystalline ZrO2–B2O3 solid solution

Codoped Er3+ and Yb3+ nanocrystalline ZrO2–B2O3 phosphor obtained by a modified sol–gel method is demonstrated. The addition of up to 2.5 mol% B2O3 to nanocrystalline ZrO2:Yb(2%), Er(1%) keep the tetragonal rare-earth stabilized ZrO2 phase; whereas higher B2O3 content destabilize the tetragonal phase, leading to the tetragonal to monoclinic transition with no tetragonal ZrO2 phase segregation. Visible upconversion of the luminescent active ions, Er3+ and Yb3+, depend strongly on B2O3 content. The PL intensity is strongly quenched for high B2O3 content due to increasing multiphonon relaxation processes related to BO and BOB vibronic modes.