CaWO_(4) polycrystals with fixed Yb^(3+)and various Er^(3+)concentrations are synthesized via the high temperature solid state method.The crystal structure of the polycrystals is characterized by means of x−ray diffraction.The upconversion properties of the polycrystals under the 980 nm excitation are investigated.Intense emission bands centered at 530 nm and 552 nm correspond to the transitions ^(2)H_(11/2)→^(4)I_(15/2) and ^(4)S_(3/>2)→^(4)I_(15/2 )of Er3+,respectively.The dependence of intensity of the green emission on the pump power and possible upconversion mechanism are discussed.Quantitative analysis of dependence of upconversion emission intensity on the pump power of a laser diode indicates that two-photon processes are responsible for both 530 nm and 552 nm green upconversion emissions.
展开▼
