Synthesis Process And Photoluminescence Mechanism Of Rare-earth Doped La₂Zr₂O₇Powder

Co-precipitation and calcinations method and hydrothermal and calcinationsmethod has been used to prepare rare earth doped zirconate. The products werecharacterized by TG-DSC, XRD, SEM, EDS and photoluminescence excitation andemission spectroscopy. The effects of the synthetic and rare earth ions on structure,morphology and optical properties were discussed.The co-precipitation and calcinations method was researched and improved. Theparticles were spherical, size uniformity, about50nm and good dispersivity. SomeLaOCl columned crystallines were generated in hydrothermal and calcinations method;the diameter was50–100nm and the length was500–1000nm. The LaOClnanocrystallines were difficult to take off; as a result, this method could hardly get pureLa2Zr2O7.The spectra of Er3+-doped La2Zr2O7were discussed; the peaks were correspondedto the energy level transitions. The amount of the doping ions and fluorescencequenching resulted to the change of light intensity. Er3+performed different betweencrystalline state and amorphous state. The strongest emission peak was550nm incrystalline state and562nm in amorphous state. The fluorescence quenching was weakwhen Er3+in amorphous state.The spectra of the Ho3+-doped La2Zr2O7were discussed; the peaks werecorresponded to the energy level transitions. The changes of intensities were same as theEr3+-doped particles. The crystallization of Ho3+-doped particles wasn’t finished at800oC; the strongest emission peak was553nm in crystalline state, and Ho3+-dopedparticles were non-luminace in amorphous state.The increasing of the doped ions made fluorescence quenching stronger inEr3+/Ho3+co-doped particles, but the emissions of Ho3+improved obviously when theratios of Er3+/Ho3+were1:2. There were overlapped energy levels between Er3+andYb3+. As a result, when increasing the amount of the Yb3+, the intensity of Er3+/Yb3+doped particles decreased. On the contrary, when increasing the amount of the Yb3+, theintensity of Ho3+/Yb3+doped particles increased.The spectra of Eu3+-doped La2Zr2O7were discussed; the peaks were correspondedto the energy level transitions. The intensity kept increasing, but the growth ratedecreased; this indicated that the fluorescence quenching of Eu3+was weaker than Ho3+and Er3+.For the particles prepared by hydrothermal and calcinations method, the well-crystallized (La1-xLnx)OCl made the fluorescence quenching stronger, and the Ho3+ doped particles performed well in luminescence when calcined in800oC.