Preparation And Temperature Sensing Properties Of Rare Earth/Transition Metal Doped Phosphors

Fluorescence intensity ratio temperature measurement technology is the use of fluorescent material luminescence and temperature relationship to measure temperature.Rare Earth ions/Transition Metal ions are often used as luminescent centers for luminescent materials.Most of the studies on temperature measurement of single luminescent center fluorescent materials focus on rare earth thermal coupling level pairs.However,the energy gap between the two thermal coupling energy levels is limited within the range of 200-2000 cm^-1,which is not conducive to improving the temperature sensitivity of fluorescent materials.A feasible way to solve the inherent limitations of rare earth thermally coupled level fluorescent materials is to combine two different and distinguishable dual-emission center signals as FIR signals.Double emission center refers to a fluorescent material having two independent emission centers.Using two different ions to emit light separately is one of the ways to realize dual emission centers.In this method,two kinds of emission can be distinguished in the whole spectral range by selecting the ions and the matrix reasonably,so as to prepare the temperature sensing fluorescent materials with good resolution and high sensitivity.Therefore,phosphors doped with two different ions were prepared.The material structure,ion luminescence and temperature sensing performance were studied.A series of Ca_2-xSr_xMg Si₂O₇:Ce³⁺,Eu²⁺（x=0,0.5,1,1.5,2）phosphors were synthesized via high temperature solid state reaction method.After the phosphor is excited at 342 nm,the emission peaks of Ce³⁺and Eu²⁺in the fluorescence spectrum almost have no overlapping part.When the phosphor is heated,the luminescence of these two ions shows different response to the change of temperature.The luminescence intensity of Ce³⁺and Eu²⁺ions can be used as the fluorescence intensity ratio signal.The maximum relative sensitivity of the phosphor can be calculated as 4.60%K-1（293-413 K）by using the fluorescence intensity ratio and temperature function obtained by software analysis.It means that Ca_2-xSr_xMg Si₂O₇:Ce³⁺,Eu²⁺phosphor is a potential optical thermometer material.The Ca₂Mg Si₂O₇:Bi³⁺,Eu³⁺phosphors with double luminescence centers were prepared by high temperature solid phase method.After 287 nm excitation,the ratio of Bi³⁺（³P₁→¹S₀）and Eu³⁺（⁵D₀→⁷F₂）luminescence intensity is temperature-dependent.The maximum calculated relative sensitivity of this luminescent material is 0.66%K^-1（293-573 K）.Two groups of Ca₁₄Al₁₀Zn₆O₃₅ inorganic phosphors co-doped Ti⁴⁺and Eu³⁺(Yb³⁺and Er³⁺)were prepared by high temperature solid-state method.Due to the different electronic configurations of doped ions,Ti⁴⁺ions in the matrix are more prone to thermal quenching than Eu³⁺ions in the 293-473 K temperature range,the maximum relative sensitivity and minimum temperature uncertainty are 1.41%K^-1 and 0.07 K,respectively.After 980 nm laser irradiation,the spectra of Yb³⁺and Er³⁺co-doped Ca₁₄Al₁₀Zn₆O₃₅ up-conversion phosphors show Er³⁺characteristics in the 500-750 nm wavelength range.The maximum value of relative sensitivity and minimum value of temperature uncertainty of up-conversion phosphors are 1.28%K^-1 and 0.08 K,respectively.In contrast,Ca₁₄Al₁₀Zn₆O₃₅ with Ti⁴⁺and Eu³⁺as luminescent centers has more advantages in temperature sensing...