Enhanced near infrared-to-visible upconversion in the CaTiO(3):Yb(3+)/Er(3+) phosphor via the host lattice modification using co-doping of Mg(2+) ions

The CaTiO(3):Er(3+)/Yb(3+) upconversion phosphor was synthesized using a simplified co-precipitation method and the effect of Mg(2+) ion co-doping was investigated on the structural and optical properties focusing on the near-infrared (NIR)-to-visible upconversion. The introduction of Mg(2+) ions into the host lattice produced substantial changes in the crystal structure, grain size, and absorption, thus leading to the enhancement in upconversion emission intensities. X-ray diffraction (XRD) analysis indicated the formation of polycrystalline CaTiO(3)–Ca(4)Ti(3)O(10) composite crystals and an increase in the crystallite size was observed upon increasing the Mg(2+) ion concentration in the samples. Elemental analysis by energy dispersive spectroscopy (EDS) suggested the substitution of Ca(2+) ions by Mg(2+) ions in the CaTiO(3) host lattice. Moreover, a change in the Yb(3+)/Er(3+) ratio from 0.25 to 1.1 indicated the redistribution of the Er(3+) or Yb(3+) ions caused by the Mg(2+) ions. These lattice deformations further resulted in an improved absorption of Er(3+) ions, exhibiting a ∼3-fold enhancement in the upconversion emission intensity (at the excitation intensity of ∼1 W cm(−2)).