Optical temperature sensing properties of Er 3+ , Yb 3+ co-doped NaGd(MoO 4 ) 2 phosphor

Thermal‐couple levels of 4S3/2 and 2H11/2 in Na(Ca, Sr)La(VO4)2:Er3+ phosphors for potential optical thermometers

“…The PL emission spectra and intensity of the thermally-coupled 2 H 11/2 → 4 I 15/2 (525 nm) to 4 S 3/2 → 4 I 15/2 (547 nm) transitions for the NSLVO:0.05Er 3+ phosphor showed the same situation as the NCLVO:0.05Er 3+ phosphor as displayed in Figure 9A. With the help of Equations (6) and (7), the A and ΔE/k values for the NSLVO:0.05Er 3+ phosphor were found to be 15.57 and 1082.08, and the S a also had an upward tendency while the maximum S a was about 7.69 × 10 −3 K −1 at 483 K as shown in Figure 9B,C. It should be noted that the maximum S a value of the NCLVO:0.05Er 3+ phosphor was higher than the NSLVO:0.05Er 3+ phosphor, because the relative emission intensity of the 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 transitions between these two kinds of luminescent materials was little different and the FIR value was mainly dominated by the ratio of the thermal couples as mentioned above.…”

“…All the experimental data could be matched by a curve with a good R-Square of 0.9975, and the A and ΔE/k were found to be about 18.23 and 1659.70. Moreover, sensing sensitivity is very significant for optical thermometers and the absolute sensing sensitivity (S a ) could be calculated as following: 41 The meanings of those parameters are the same as Equation (6). Therefore, the dependence of S a value on different temperatures ranging from 303 to 483 K was performed as shown in Figure 8C.…”

“…The conventional contact thermometers based on bimetal and glass liquid would frequently suffer from environmental disturbance and long response time which result in a difficulty of measuring temperature distribution in some areas 2−4 . Fortunately, the optical thermometers based on the fluorescence intensity ratio (FIR) technique in luminescent materials have been widely investigated and promised for next‐generation noncontact thermometers as a potential application in electrical power stations, biological environments, oil refineries, coal mines, and intracellular temperature measurements due to lots of obvious advantages of high detection spatial resolution, high precision, and excellent sensing sensitivity in comparison with the conventional contact thermometers as we mentioned above 5−8 . The FIR technique could estimate the sensing sensitivity of luminescent materials via comparing the temperature‐dependent emission intensity between in a pair of thermal‐couple levels at varying temperatures 9 …”

Synthesis and up‐conversion of Er3+ and Yb3+ Co‐doped LiY(MoO4)2@SiO2 for optical thermometry applications

“…For optical thermometry, molybdates can be considered as good hosts for luminescence materials due to their excellent thermal and chemical stability. Different molybdates as host materials for optical thermometry have been studied intensively, such as NaGd(MoO 4 ) 2 , NaY(MoO 4 ) 2 , La 2 MoO 6 , SrMoO 4 , and etc . The large interspace of the molybdate structure can enhance the covalent character and improve the amount of rare earth ions absorbed into the matrix, thereby improving the luminous efficiency of the material.…”

“…Different molybdates as host materials for optical thermometry have been studied intensively, such as NaGd(MoO 4 ) 2 , NaY(MoO 4 ) 2 , La 2 MoO 6 , SrMoO 4 , and etc. [20][21][22][23][24][25] The large interspace of the molybdate structure can enhance the covalent character and improve the amount of rare earth ions absorbed into the matrix, thereby improving the luminous efficiency of the material. Therefore molybdate phosphors co-doped with Er 3+ and Yb 3+ have high a luminescent efficiency under excitation.…”