Enhancing negative thermal quenching effect via low-valence doping in two-dimensional confined core–shell upconversion nanocrystals

2018 ◽  
Vol 6 (43) ◽  
pp. 11587-11592 ◽  
Author(s):  
Lei Lei ◽  
Jienan Xia ◽  
Yao Cheng ◽  
Yuansheng Wang ◽  
Gongxun Bai ◽  
...  
Keyword(s):  
Emission Intensity ◽  
Thermal Quenching ◽  
Core Shell ◽  
Two Dimensional ◽  
Quenching Effect ◽  
Upconversion Nanocrystals

Doping low-valence ions in core–shell NC is applied to improve negative thermal quenching effect. With the increase in temperature from 293 to 413 K, the UC emission intensity of 20Yb/2Er : NaGdF4 (12 nm) increases by 2.2 times, whereas that of NaGdF4@20Ca/20Yb/2Er: NaGdF4 (11 nm) increases by 10.9 times.

Inverse thermal quenching effect in lanthanide-doped upconversion nanocrystals for anti-counterfeiting

2018 ◽  
Vol 6 (20) ◽  
pp. 5427-5433 ◽  
Author(s):  
Lei Lei ◽  
Daqin Chen ◽  
Can Li ◽  
Feng Huang ◽  
Junjie Zhang ◽  
...  
Keyword(s):  
Energy Level ◽  
Thermal Quenching ◽  
Defect State ◽  
Quenching Effect ◽  
High Security ◽  
Upconversion Nanocrystals

An inverse thermal quenching effect is actualized in uniform lanthanide-doped Na3ZrF7 by artificially introducing defect state with an appropriate energy level. These kinds of systems are very suitable for anti-counterfeiting with high security.

Improvement of luminescence properties of rubidium vanadate, RbVO3, phosphors by erbium doping in the crystal lattice

2017 ◽  
Vol 41 (12) ◽  
pp. 4788-4792 ◽  
Author(s):  
S. W. Kim ◽  
T. Hasegawa ◽  
M. Muto ◽  
A. Toda ◽  
T. Kaneko ◽  
...  
Keyword(s):  
Crystal Lattice ◽  
Emission Intensity ◽  
Thermal Quenching ◽  
Luminescence Properties ◽  
Erbium Doping ◽  
Quenching Effect

The thermal quenching effect of RbVO3 phosphor was effectively improved by Er3+ doping into the lattice, as a result, the emission intensity of the phosphor was successfully enhanced.

scholarly journals Structural Disorder and Collective Behavior of Two-Dimensional Magnetic Nanostructures

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1392
Author(s):  
David Gallina ◽  
G. M. Pastor
Keyword(s):  
Interaction Energy ◽  
Time Evolution ◽  
Magnetic Nanostructures ◽  
Thermal Quenching ◽  
Structural Disorder ◽  
Square Lattice ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Two Dimensional ◽  
Energy Landscapes

Structural disorder has been shown to be responsible for profound changes of the interaction-energy landscapes and collective dynamics of two-dimensional (2D) magnetic nanostructures. Weakly-disordered 2D ensembles have a few particularly stable magnetic configurations with large basins of attraction from which the higher-energy metastable configurations are separated by only small downward barriers. In contrast, strongly-disordered ensembles have rough energy landscapes with a large number of low-energy local minima separated by relatively large energy barriers. Consequently, the former show good-structure-seeker behavior with an unhindered relaxation dynamics that is funnelled towards the global minimum, whereas the latter show a time evolution involving multiple time scales and trapping which is reminiscent of glasses. Although these general trends have been clearly established, a detailed assessment of the extent of these effects in specific nanostructure realizations remains elusive. The present study quantifies the disorder-induced changes in the interaction-energy landscape of two-dimensional dipole-coupled magnetic nanoparticles as a function of the magnetic configuration of the ensembles. Representative examples of weakly-disordered square-lattice arrangements, showing good structure-seeker behavior, and of strongly-disordered arrangements, showing spin-glass-like behavior, are considered. The topology of the kinetic networks of metastable magnetic configurations is analyzed. The consequences of disorder on the morphology of the interaction-energy landscapes are revealed by contrasting the corresponding disconnectivity graphs. The correlations between the characteristics of the energy landscapes and the Markovian dynamics of the various magnetic nanostructures are quantified by calculating the field-free relaxation time evolution after either magnetic saturation or thermal quenching and by comparing them with the corresponding averages over a large number of structural arrangements. Common trends and system-specific features are identified and discussed.

Plasmonic Dual‐Enhancement and Precise Color Tuning of Gold Nanorod@SiO 2 Coupled Core–Shell–Shell Upconversion Nanocrystals

2017 ◽  
Vol 27 (36) ◽  
pp. 1701842 ◽  
Author(s):  
Fengwen Kang ◽  
Jijun He ◽  
Tianying Sun ◽  
Zhi Yong Bao ◽  
Feng Wang ◽  
...  
Keyword(s):  
Gold Nanorod ◽  
Core Shell ◽  
Color Tuning ◽  
Upconversion Nanocrystals

Emerging core-shell nanostructured catalysts of transition metal encapsulated by two-dimensional carbon materials for electrochemical applications

Nano Today ◽  
2018 ◽  
Vol 22 ◽  
pp. 100-131 ◽  
Author(s):  
Duy Thanh Tran ◽  
Tolendra Kshetri ◽  
Nguyen Dinh Chuong ◽  
Jagadis Gautam ◽  
Hoa Van Hien ◽  
...  
Keyword(s):  
Transition Metal ◽  
Carbon Materials ◽  
Nanostructured Catalysts ◽  
Core Shell ◽  
Two Dimensional ◽  
Electrochemical Applications

Anchoring Core–Shell Cu@Cu2O Nanoparticles to Two-Dimensional Carbon Nanosheets for Bacterial Disinfection

2021 ◽  
Vol 4 (9) ◽  
pp. 9831-9841
Author(s):  
Guihong Sun ◽  
Shanshan Jia ◽  
Xiaoyan Zhang ◽  
Zewen Kang ◽  
Malin Cui ◽  
...  
Keyword(s):  
Core Shell ◽  
Two Dimensional ◽  
Carbon Nanosheets ◽  
Cu2o Nanoparticles ◽  
Bacterial Disinfection

Thermally boosted upconversion and downshifting luminescence in Sc2(MoO4)3:Yb/Er with two-dimensional negative thermal expansion

2021 ◽  
Author(s):  
Jinsheng Liao ◽  
Minghua Wang ◽  
Fulin Lin ◽  
Zhuo Han ◽  
Datao Tu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Near Infrared ◽  
Negative Thermal Expansion ◽  
Thermal Quenching ◽  
Relative Sensitivity ◽  
Strong Temperature Dependence ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Higher Temperature

Abstract Lanthanide (Ln3+)-doped phosphors generally suffer from thermal quenching, in which their photoluminescence (PL) intensities decrease at the higher temperature. Herein, we report a class of unique two-dimensional negative-thermal-expansion phosphor of Sc2(MoO4)3:Yb/Er. By virtue of the reduced distances between sensitizers and emitters as well as confined energy migration with increasing the temperature, a 45-fold enhancement of green upconversion (UC) luminescence and a 450-fold enhancement of near-infrared downshifting (DS) luminescence of Er3+ are achieved from 25 to 500 ˚C. The thermally boosted UC and DS luminescence mechanism is systematically investigated through in situ temperature-dependent Raman spectroscopy, synchrotron X-ray diffraction and PL dynamics. Moreover, the luminescence lifetime of 4I11/2 of Er3+ in Sc2(MoO4)3:Yb/Er displays a strong temperature dependence, enabling ratiometric thermometry with the highest relative sensitivity of 13.4%/K at 298 K. These findings may gain a vital insight into the design of negative-thermal-expansion Ln3+-doped phosphors for versatile applications.

In-cylinder thermographic PIV combined with phosphor thermometry using ZnO:Zn

2021 ◽  
pp. 146808742110485
Author(s):  
Andreas Kopf ◽  
Valerio Frattina ◽  
Michele Bardi ◽  
Torsten Endres ◽  
Gilles Bruneaux ◽  
...  
Keyword(s):  
Fuel Injection ◽  
Thermal Quenching ◽  
Temperature Fields ◽  
Ratio Method ◽  
Calibration Data ◽  
Two Dimensional ◽  
Ic Engine ◽  
Thermographic Phosphor ◽  
Phosphor Thermometry ◽  
Coated Surfaces

Two-dimensional thermographic particle image velocimetry (T-PIV) is presented for the in situ measurement in optically accessible internal combustion (IC) engines. Temperature and velocity measurements are combined using thermographic phosphor particles as tracers for PIV. For three commercially available phosphors (BAM:Eu2+, ZnO, and ZnO:Zn), temperature sensitivity, luminescence intensity at high temperatures and laser-fluence dependence were evaluated for phosphor-coated surfaces in a high-temperature cell. ZnO:Zn was identified as the best-suited candidate for engine in-cylinder measurements and further analyzed in the aerosolized state at temperatures up to 775 K to generate calibration data required for signal quantification in engine experiments. T-PIV was successfully applied in the IC engine to simultaneously obtain instantaneous two-dimensional velocity and temperature fields using the intensity-ratio method. Despite a measurement uncertainty (±1σ basis) of only 3.7 K at 317 K (1.2%) to 24.4 K (4.2%) at 575 K, this technique suffers from low signal intensities due to thermal quenching at increasing temperatures, which leads to reduced accuracy as the piston approaches top dead center. Thermographic measurements were successful to visualize local temperature changes due to evaporative cooling after fuel injection. The measured mean gas temperatures agreed well with zero-dimensional simulations that use additional wall-temperature measurements from thermographic phosphor measurements based on the lifetime method as input for heat transfer calculations.

Sign in / Sign up

Export Citation Format

Share Document