Photocatalytic effect of TiO2-coated CaLa2(MoO4)4 and CaLa2(MoO4)4:Er/Yb nano core–shells and upconversion photoluminescence properties of CaLa2(MoO4)4:Er/Yb phosphors

• TiO2-coated CaLa2(MoO4)4:Er/Yb nano core–shells were made by two-step methods.
• Nano core–shells showed a fine morphology with particle sizes of 10–20 nm.
• 10 wt% TiO2-coated CaLa2(MoO4)4:Er/Yb provided the best photocatalytic effect.
• UC intensities exhibited a strong 525 nm and a weak 550 nm emission bands.
• The CIE color coordinates showed a good match with yellowish green emissions.

TiO2-coated CaLa2(MoO4)4 and CaLa2(MoO4)4:Er/Yb nano core–shells were successfully synthesized using two-step procedures of the microwave sol–gel and ultrasonic methods. Well-crystallized nano core–shells showed a fine and homogeneous morphology with particle sizes of 10–20 nm. The degradation efficiency for TiO2-coated CaLa2(MoO4)4 and CaLa1.7(MoO4)4:Er0.1Yb0.2 under visible light resulted in the order as 10 > 15 > 5 wt%. Under excitation at 980 nm, the upconversion intensities of CaLa1.7(MoO4)4:Er0.1Yb0.2 and CaLa1.5(MoO4)4:Er0.05Yb0.45 particles exhibited a strong 525 nm and a weak 550 nm emission bands in the green region. The CIE diagram showed a good match with yellowish green emissions.

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