Er3+/Yb3+ co-doped CaMoO4 (CaMoO4:Er3+/Yb3+) particles were successfully synthesized by a cyclic microwave-assisted metathetic (MAM) method, followed by further heat-treatment. Well-crystallized CaMoO4:Er3+/Yb3+ particles were formed after heat-treatment at 600 οC for 3 h, and showed a fine and homogeneous morphology with sizes of 0.2-1 μm. With excitation at 980 nm, CaMoO4:Er3+/Yb3+# 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 upconversion (UC) intensity of CaMoO4:Er3+/Yb3+# particles was much higher than those of the CaMoO4:Er3+ and CaMoO4:Er3+/Yb3+ particles. The Raman spectra of CaMoO4:Er3+, CaMoO4:Er3+/Yb3+, CaMoO4:Er3+/Yb3+# and CaMoO4:Er3+/Yb3+## 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).

Keywords: Upconversion photoluminescence, CaMoO4:Er3+/Yb3+ particles, Cyclic microwave, Metathetic method, Raman spectroscopy.