Charge transfer bands of Mo-O and photoluminescence properties of micro-material Y2MoO6:Eu3+ red phosphor

•Y2MoO6:Eu3+ phosphors have been prepared by solid-state reaction and sol–gel technique.•Y2MoO6:Eu prepared using solid state method showed much stronger red emission under the n-UV excitation.•With a decrease of the crystalline size, the excitation bands of O–Mo CT shift to the short wavelength.•We can include that the origin of CT blue-shifts mainly came from the vacancies of O6 sites within the crystals through quantitative calculation based on the chemical bond viewpoint.