Xiaona Chai

Bright dual-mode green emission and temperature sensing properties in Er3+/Yb3+ co-doped MgWO4 phosphor

Er3+/Yb3+ co-doped MgWO4 phosphor was synthesized by a solid state reaction method and the phase, photoluminescence and temperature sensing properties were analyzed. The phosphor has shown intense visible green emission via up-conversion process on near-infrared (980 nm) excitation and down-conversion process on 379 nm excitation and thus behaves as a dual-mode phosphor. In the up-conversion and down-conversion emission, the 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions of the Er3+ ion portray a temperature dependent behavior and have been used for optical temperature sensor by means of the fluorescence intensity ratio method. Moreover, we compared the curves of S in the continuous temperature range (83–583 K) and the two sectional temperature ranges in up-conversion process. It is found that the phosphor can be operated over a temperature range of 83–583 K with a maximum sensitivity of about 0.0093 K−1 at 583 K. The results indicate that the Er3+/Yb3+ co-doped MgWO4 phosphor is a potential candidate to be used in display devices and optical temperature sensors.

Color-tunable upconversion photoluminescence and highly performed optical temperature sensing in Er 3+ /Yb 3+ co-doped ZnWO 4 .

Er3+/Yb3+ co-doped ZnWO4 phosphors were synthesized by a solid state reaction method and their structure, photoluminescence and temperature sensing properties were characterized. The color-tunable upconversion emissions (from green to red) were observed by increasing the doped Er3+/Yb3+ concentration. The temperature sensing properties were studied by using the fluorescence intensity ratio technique in the temperature range of 83-583 K, and high performance was obtained. The maximum sensitivity is found to be 0.0099 K-1 at 583 K. The XRD Rietveld refinement revealed that the phosphors crystallized in monoclinic structure with the space group P2/c (13) at room temperature. The results suggest that the phosphors could be an exceptional choice for next generation luminescence-based temperature sensing devices as well as in multiple biolabels.

Upconversion luminescence and temperature-sensing properties of Ho3+/Yb3+-codoped ZnWO4 phosphors based on fluorescence intensity ratios

Ho3+/Yb3+-codoped ZnWO4 phosphors were synthesized using a solid state reaction method and their structures, upconversion (UC) luminescence, and temperature-sensing properties were investigated. The obtained ZnWO4:0.01Ho3+/xYb3+ phosphors crystallized in the monoclinic phase with space group P2/c. Under 980 nm excitation, bright green [(5F4, 5S2) → 5I8], weak red (5F5 → 5I8), and near-infrared emissions [(5F4, 5S2) → 5I7] were observed. The optimal Ho3+ and Yb3+ doping concentrations in ZnWO4 were 0.01 and 0.15, respectively. The near-infrared-green (I757/I540) and red-green (I641,665/I540,549) fluorescence intensity ratios (FIRs) were studied as a function of temperature at 83–503 K. The sensitivity of the ZnWO4:0.01Ho3+/0.15Yb3+ phosphors was also discussed and their potential application as thermal sensors in luminescence thermometry was analyzed using a four-level system and the intensity ratio of the red and green emissions. ZnWO4:0.01Ho3+/0.15Yb3+ phosphors could potentially be applied as optical temperature-sensing materials.

Enhanced electrical properties, color-tunable up-conversion luminescence, and temperature sensing behaviour in Er-doped Bi3Ti1.5W0.5O9 multifunctional ferroelectric ceramics

Er-doped Bi3Ti1.5W0.5O9 (BTW-x) ferroelectric ceramics were prepared by a conventional solid-state reaction synthesis method, and their structure, electrical properties, up-conversion (UC) luminescence, and temperature sensing behaviour were investigated. A high piezoelectric coefficient d33 (9.6 pC/N), a large remnant polarization Pr (12.75 μC/cm2), a high Curie temperature Tc (730.2 °C), and the optimal luminescent intensity are obtained for the samples at x = 0.05. By changing the Er doped concentration, the BTW-x ceramics are capable of generating various UC spectra and the color could be tunable from green to yellow. According to the fluorescence intensity ratio of green emissions at 532.6 nm and 549.2 nm in the temperature range from 83 K to 423 K, optical temperature sensing properties are investigated and the maximum sensing sensitivity is found to be 0.00314 K−1 at 423 K. The results conclude that BTW-x would be a candidate in high temperature sensor, fluorescence thermometry, and opto-electronic...

Dual-Mode Luminescence, Temperature Sensing and Dielectric Performance in Pr3+/Er3+ Co-Doped BaTiO3-CaTiO3 Diphase Ferroelectric Oxides

Pr3+/Er3+ co-doped BaTiO3-CaTiO3 diphase ferroelectric oxides were prepared by a conventional solid-state reaction method and their phase, microstructure, photoluminescence, dielectric and ferroelectric properties were investigated by X-ray diffractometer, scanning electron microscope, electrical measurements and luminescence spectrometer etc. The result presents that a dual-mode luminescence of both a down-conversion red emission (˜612 nm) under an ultraviolet excitation and an up-conversion green emission (˜550 nm) under a near-infrared excitation in the same material of Pr3+/Er3+ co-doped BaTiO3-CaTiO3 diphase ferroelectric oxides. Meanwhile, the 405 nm (1S0→1I6), 468 nm (3P0→3H4), and 550 nm (3P0→3H5) emission lights under excitation at 213 nm are stronger than the emission under the 333 nm excitation. The ferroelectric and dielectric performances degraded with the increasing Er3+ doping concentration. These ceramics, with good temperature sensing properties, may be useful for temperature sensing devices.

Improved electrical properties and dual-mode photoluminescence in (1−x)(Na 0.475 K 0.475 Li 0.05 )NbO 3−x (Er 0.5 Na 0.5 )TiO 3 lead-free multifunctional ceramics

(1-x)(Na0.475K0.475Li0.05)NbO3-x(Er0.5Na0.5)TiO3 (0≤x≤0.025) lead-free multifunctional ceramics were prepared by a conventional solid-state reaction method. Their phase, photoluminescence, dielectric, ferroelectric and piezoelectric properties were investigated systematically by the X-ray Diffraction (XRD), scanning electron microscopy (SEM) spectrophotometer and electrical property measurements. The relationship of composition, microstructure and electrical properties and the mechanisms of up-conversion and down conversion emissions were analyzed detailed. The results show that the ceramics exhibit the optimum piezoelectric and ferroelectric properties when their compositions lie at the nearby of the morphotropic phase boundary (MPB). Moreover, these ceramics can emit strong 550 nm green light when they were excited by a nearinfrared (980 nm) light and a 486 nm blue light, respectively. Together with the excellent ferroelectric properties and good dielectric properties, these ceramics should be one of the promising candidates for multifunctional optoelectronic applications.