Preparation And Investigation Of Single-host Dual-emitting Fluorescent Materials With Spectra Tunable And Temperature Sensing Properties

Rare earth ions doped single-host dual-emitting fluorescent materials with the characteristics of spectra tunable and temperature sensitivity differences have potential application value in white LED,temperature sensing,fluorescent probe and other fields.Therefore,this dissertation concentrates on single-host dual-emitting fluorescent materials and deeply examines color tunable and fluorescence temperature sensing performance.Ca₈ZrMg（PO₄）₆（SiO₄）:Eu³⁺phosphors were synthesized by a simple high temperature solid-state method.Under 295 nm excitation,Ca₈ZrMg（PO₄）₆（SiO₄）:Eu³⁺phosphors show two emission peaks at 470 and 615 nm,which are attributed to the charge transfer transition from Zr⁴⁺to O^2-and the characteristic ⁵D₀?⁷F₂transition of Eu³⁺ions,respectively.In addition,the energy transfer process in view of dipole-quadrupole mechanism occurs between Zr⁴⁺-O^2-charge transfer band and Eu³⁺ions.The color coordinate of Ca₈ZrMg（PO₄）₆（SiO₄）host is（0.2186,0.2858）,but with the increase of Eu³⁺concentration,the luminescent color of the samples gradually changes from white to orange reddish,and the corresponding color coordinates change from（0.3252,0.3043）to（0.5413,0.3295）.The temperature-dependent spectra depicts that Ca₈ZrMg（PO₄）₆（SiO₄）:Eu³⁺with high thermal stability.Ca₈ZrMg（PO₄）₆（SiO₄）:Eu²⁺,Eu³⁺dual-emitting phosphors were fabricated in a reducing atmosphere.Under the excitation of 297 nm light,blue emission of Eu²⁺at414 nm and red emission of Eu³⁺at 614 nm can be observed in the samples.In addition,the thermal-quenching phenomenon of Eu²⁺and Eu³⁺are different by temperature-dependent spectra and the FIR of I_Eu²⁺/I_Eu³⁺is linear.The absolute temperature sensitivity is 1.13-5.94%K^-1.Eu²⁺/Eu³⁺co-activated Ca₉Zn_1.5（PO₄）₇ fluorescent materials were fabricated by high temperature solid-state reduction.Upon 350 nm excitation,the emission spectra contain characteristic emission peaks of Eu²⁺and Eu³⁺ions,providing good signal discrimination for temperature detection.The FIR of I_Eu³⁺/I_Eu²⁺exhibit obvious temperature-dependence in the temperature range of 293⁴73 K due to the different thermal-quenching behaviors of Eu²⁺:4f-5d and Eu³⁺:4f-4f transition.The maximum absolute temperature sensitivity and relative temperature sensitivity were 0.0023 K^-1and 1.52%K^-1.Ca₉Mg_1.5（PO₄）₇:Eu²⁺/Eu³⁺fluorescence materials were successfully prepared by high temperature solid-state method in N₂/H₂（95%/5%）reducing atmosphere.Not only the blue emission of Eu²⁺and the red emission of Eu³⁺,but also the two-sites emissions in blue and red regions of Eu²⁺can be used as signal of fluorescence intensity ratio.According to the FIR(I₆₀₀/I₄₁₅)of Eu²⁺,the maximum absolute sensitivity and relative sensitivity of the target phosphor are 0.064 K^-1 and 1.192%K^-1,respectively.