Controlled hydrothermal processing of multiform (Y0.95Eu0.05)PO4 crystals and comparison of photoluminescence

Abstract With maleic acid (MA) as an original and efficient structure/morphology modifier, tetragonal (t-) and hexagonal (h-) structured (Y0.95Eu0.05)PO4 nano/microcrystals with the diverse morphologies of nanoparticles, nanospindles, nanosquares, nanodisks and microprisms have been successfully synthesized via hydrothermal reaction at 180 oC for 24 h. The systematic study demonstrated that solution pH, MA/(Y0.95Eu0.05)3+ molar ratio and PO43-/(Y0.95Eu0.05)3+ molar ratio are three crucial factors that synergistically determine phase structure and crystal shape/size of the product, and the underlying mechanisms were proposed. Photoluminescence of the (Y0.95Eu0.05)PO4 crystals was revealed to be strongly morphology/structure dependent, which was discussed in detail in terms of excitation, emission, asymmetry factor of luminescence, quantum yield, fluorescence decay, emission color and thermal stability.