An Eu3+ singly doped material and a K+-Eu3+ co-doped calcium carbonate phosphor were synthesized successfully by microwave assisted sintering at low temperature. The sintering condition was set at 270 degrees C for 3 h in air. The structure and micro-morphology of samples were characterized and analyzed by X-ray powder diffraction (XRD) and scanning electronic microscope (SEM). Results showed that Eu3+ and K+ ions were uniformly introduced into the host lattice of CaCO3, taking place of Ca2+ ions. The photoluminescence (PL) properties were characterized by PL, PL excitation spectroscopy. The maximum photoluminescence intensity was obtained when the molar concentration of Eu3+ was 0.08. Under the excitation of 394 nm, the transitions of D-5(0) -> F-7(J) (J = 0-5) for Eu3+ were observed, and the luminescent intensities of Eu3+-K+ co-doped CaCO3 phosphors could be greatly increased. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.