Improvement Of Ag Nanoparticle And Al Sheet On PL Characteristics And Temperature Sensing Performance Of CaSrSiO₄:Yb³⁺,Er³⁺ Phosphor

The photoluminescence materials doped earth rare ions have presented comprehensive application prospect because they have a series of excellent virtues,such as high efficiency,stable performance and so on.Especially,nanophosphor doped earth rare elements takes on unique advantages in the field of optical temperature sensor working at high temperature environment.Therefore,a kind of CaSrSiO₄ nanophosphor co-doped Yb and Er ions with high fluorescence intensity has been prepared,and then photoluminescence efficiency is further improved by co-doping with silver nanoparticles.At the same time,the relationship of the fluorescence intensity ratio and sensitivity and temperature is investigated.In particular the CaSrSiO₄:Yb³⁺,Er³⁺nanophosphor is firstly blended into aluminium sheet and it has show outstanding temperature sensing performance.The specific research works in the thesis include as follows:Firstly,a series of ytterbium,erbium single-doped and co-doped CaSrSiO₄nanophosphors have been prepared by high temperature solid-state method.XRD and SEM characterization results show that the dopants of ytterbium and erbium ions have little effect on the crystal structure,nanoparticle morphology and size.Photoluminescence spectra of CaSrSiO₄ nanophosphors doped with different Yb/Er concentration ratios were measured under the excitation of 980 nm infrared semiconductor laser,and there exist four main photoluminescence peaks whose center wavelengths at 490,522,545 and 652 nm,respectively.The PL intensity changes of the peaks present a bimodal structure with the increase of Yb³⁺concentration.When the Er³⁺doping concentration is kept as 1 mol%,the optimum value of Yb³⁺concentration is 9 and 17 mol%,and the intensity of the former is more intense than that of the latter.Secondly,ytterbium,erbium co-doped as well as ytterbium,erbium and silver particles co-doped CaSrSiO₄ nanophosphors were prepared by the same method.The results of XRD and SEM characterization still show that the doping of silver nanoparticle has no obvious influence on the crystal structure and morphology of CaSrSiO₄:Yb³⁺,Er³⁺nanophosphor.The optimized Ag nanoparticle doping concentration of is 0.6 mol%.Compared to the photoluminescence intensity at 522 nm of CaSrSiO₄:9Yb³⁺,1Er³⁺sample,the intensity of CaSrSiO₄:9Yb³⁺,1Er³⁺,0.6Ag nanophosphor is enhanced by 2.3 times.The changes of the fluorescence intensity ratio and sensitivity of CaSrSiO₄:9Yb³⁺,1Er³⁺and CaSrSiO₄:9Yb³⁺,1Er³⁺,0.6Ag nanophosphors as a function of temperature of were investigated at the range of303-720 K.The both relationships between the sensitivity and temperature of two samples present the similar single-peak structure.At 423 K,the sensitivity of CaSrSiO₄:9Yb³⁺,1Er³⁺nanophosphor reaches its maximum value,about 0.0057 K^-1;The maximum sensitivity of CaSrSiO₄:9Yb³⁺,1Er³⁺,0.6Ag nanopowder,however,is at 363 K and its value is 0.0073 K^-1,including that the temperature sensing performance of the latter is better than that of the former.Finally,the aluminium sheets blended with CaSrSiO₄:1Er³⁺,xYb³⁺nanophosphors were prepared by secondary high temperature sintering method.The optimum Yb³⁺doping concentration is still 9 mol%after CaSrSiO₄:1Er³⁺,xYb³⁺nanophosphors being blended into aluminum sheets.Unlike the most of luminescent materials,the photoluminescence intensity of Al:CaSrSiO₄:9Yb³⁺,1Er³⁺keeps continued increasing with the increase of temperature,and shows a trend of slow enhancement first and then fast enhancement.By comparing the sensitivity curves of Al:CaSrSiO₄:9Yb³⁺,1Er³⁺and CaSrSiO₄:9Yb³⁺,1Er³⁺samples in the temperature range of 303-723 K,it can be found that the optical temperature sensing performance is remarkable improved when the CaSrSiO₄:9Yb³⁺,1Er³⁺nanophosphors is blended into aluminium sheets.