Dual‐mode optical thermometry and multicolor anti‐counterfeiting based on Bi³⁺/Er³⁺ co‐activated BaGd₂O₄ phosphor

Abstract

Here, Bi3+, Er3+ co‐activated gadolinium phosphors with multimode emission properties are prepared, which can emits blue, green, and orange light under the excitation of ultraviolet, 980 and 1550 nm, respectively. Moreover, BaGd2O4:Bi3+, Er3+ can show multicolor luminescence under different excitation conditions, such as pump light source, ambient temperature, working current, and other factors. Based on the dynamic luminescence characteristics, the dynamic anti‐counterfeiting experiments are designed based on the phosphor. At the same time, the material also shows multimode temperature sensing characteristics. Under the excitation of 980 nm laser, three strong up‐conversion signals Er3+ ions are generated at 528 nm (2H11/2), 555 nm (4S3/2), and 668 nm (4F9/2), which have different temperature dependences. Based on the fluorescence intensity ratio between thermal‐coupled energy levels (2H11/2/4S3/2) and nonthermal‐coupled energy levels (2H11/2/4F9/2) of Er3+ ions, respectively, the dual‐mode temperature thermometer was constructed with high‐temperature sensitivity. In addition, the fluorescence lifetime of Bi3+ ions also has a strong temperature dependence, which can be used as another temperature detection signal, greatly improving the stability of thermometers under harsh conditions. Therefore, the material has a bright prospect in the field of anti‐counterfeiting and temperature sensing.

Improved optical thermometric sensitivity of Eu3+‐doped calcium niobate phosphor via nonstoichiometric control

“…In comparison with CaNb 2 O 6 :0.01Eu 3+ and other available phosphors (Table S2), CaNb 1.9 O 6 :0.01Eu 3+ phosphor exhibits a higher sensitivity. )] −1 (7) where I and I 0 are the emission intensities at different given temperatures T and initial emission intensity, A is a constant, and K represents the Boltzmann's constant. The activation energy is calculated accordingly as depicted in the insets of Figure 5D,E, respectively.…”

“…Optical thermometry based on fluorescence intensity ratio (FIR) technique has attracted intensive concerns owing to its unique advantages in contactless, rapid response, and high‐spatial as well as high‐temperature resolution, which is favorable for operating in harsh conditions, high‐speed moving targets, and micro‐objects 1–4 . Generally, FIR‐based optical thermometers read the ratio parameters of binary‐luminescent probes with two emission centers following distinct temperature responses, one serving as a reference signal and the other as an indicator 5–7 . So far, the great majority of current FIR temperature sensor exploits the emissions of the lanthanide ions, such as Eu 3+ /Tb 3+ , 8,9 Yb 3+ /Er 3+ , 10–12,13 Ce 3+ /Tb 3+ , 14,15 Eu 2+ /Eu 3+ , 16–18 and Pr 3+ /Tb 3+ , 19,20 to obtain two discriminable emissions.…”

“…[1][2][3][4] Generally, FIR-based optical thermometers read the ratio param-eters of binary-luminescent probes with two emission centers following distinct temperature responses, one serving as a reference signal and the other as an indicator. [5][6][7] So far, the great majority of current FIR temperature sensor exploits the emissions of the lanthanide ions, such as Eu 3+ /Tb 3+ , 8,9 Yb 3+ /Er 3+ , [10][11][12]13 Ce 3+ /Tb 3+ , 14,15 Eu 2+ /Eu 3+ , [16][17][18] and Pr 3+ /Tb 3+ , 19,20 to obtain two discriminable emissions. However, the temperature measurement performance of optical thermometers is still unsatisfactory because trivalent lanthanide ions generally suffer from the inherent disadvantages of the relatively low emission intensity and narrow excitation range due to the forbidden character by the selection rules of the 4f-4f transitions.…”

Achieving dynamic quintuple-mode luminescence in Ca3Ti2O7:Pr3+,Er3+ phosphor for anti-counterfeiting applications

“…24 For instance, Xu et al designed BaGd 2 O 4 :Bi 3+ ,Er 3+ phosphor, which could emit blue, green, and orange light under the excitation of UV light at 980 nm and 1550 nm. 25 Guo et al also proposed Ba 2 GdTaO 6 :Mn 4+ ,Er 3+ with three-mode luminescence by adjusting the excitation wavelength. 26 Xu et al designed SrZnOS:Yb 3+ ,Er 3+ , with fourmode luminescence that responded to UV light, a 980 nm laser, loaded force, and X-rays.…”