Infrared-to-visible upconversion in Er3+ and Er3+/Yb3+ activated Sb2O4 nanopowders prepared by sol–gel route

We prepared Er3+ doped and Er3+/Yb3+ codoped Sb2O4 nanocrystals by the sol–gel method. The Raman, X-ray diffraction (XRD), transmission electron microscope (TEM), and photoluminescence spectra of the samples were studied. The phonon energy of the Sb2O4 nanocrystals is very low (the maximum value being 461 cm−1). The upconversion (UC) red emission of the Er3+/Yb3+ codoped sample is very strong at 975 nm laser diode excitation. The Sb2O4 nanocrystals will be a promising luminous material.