Cyclic MAM synthesis and upconversion photoluminescence properties of CaMoO4:Er3+/Yb3+ particles

Abstract Upconversion (UC) photoluminescence of Er 3+ doped CaMoO 4 (CaMoO 4 :Er 3+ ) and Er 3+ /Yb 3+ co-doped CaMoO 4 (CaMoO 4 :Er 3+ /Yb 3+ ) particles was successfully achieved by a cyclic microwave-assisted metathetic (MAM) method, followed by heat-treatment. Well-crystallized UC CaMoO 4 :Er 3+ /Yb 3+ particles formed after heat-treatment at 600 °C for 3 h showed a fine and homogeneous morphology with particle sizes of 1–3 μm. At excitation at 980 nm, CaMoO 4 :Er 3+ /Yb 3+ particles exhibited a strong 525-nm emission band and a weak 550-nm emission band in the green region, and a weak 655-nm emission band in the red region. The UC intensities of CaMoO 4 :Er 3+ /Yb 3+ particles were much higher than that of the CaMoO 4 :Er 3+ particles. The Raman spectra of CaMoO 4 :Er 3+ and CaMoO 4 :Er 3+ /Yb 3+ particles indicated the detection of additional strong peaks at higher frequencies (618, 575, 492, 420 and 373 cm −1 ) and at lower frequencies (290 and 234 cm −1 ).