Synthesis and investigation of La,Ca-doped EuVO₄ nanoparticles with enhanced excitation by near violet light

The paper reports experimental results on features of crystal structure and luminescent properties of the Eu_1-xCa_yVO₄ nanoparticles synthesized for the first time. The Eu_1-xCa_xVO₄ compounds with x = 0, 0.05, 0.1, 0.15, and 0.20 are prepared by aqueous nitrate-citrate sol-gel synthesis. The obtained samples are characterized by XRD analysis. The Eu_1-xCa_xVO₄ samples are crystallized in tetragonal structure. Phase composition of the sample depends on the x value. Increasing concentrations of the calcium ions leads to formation of the EuVO₄ and CaV₂O₆ phases' mixture. Luminescence properties of the synthesized Eu_1-xCa_xVO₄ nanoparticles are considered in comparison with properties of the La_1-x-yEu_yCa_xVO₄ nanoparticles. Formation of two types of emission centers and arising of additional excitation band near 400 nm are observed for the both compositions. It is shown that second types of the emission centers have different structure and spectral characteristics for the Eu_1-xCa_xVO₄ and La_1-x-yEu_yCa_xVO₄ nanoparticles, whereas the 400 nm excitation band has the same origin for the both compositions. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)