The fluorescence intensity ratio (FIR) of two thermally coupled levels with temperature follows the Boltzmann equation and shows an exponential nature to the temperature that is purely dependent on the energy difference between the levels. Despite the identical energy difference between the thermally coupled levels, researchers have observed varying sensitivities for various samples. In this article, the FIR and sensitivities were calculated using the Boltzmann equation by changing various parameters such as energy difference (ΔE) and the value of the constant C. The results were compared with various reports for Er /Yb ions. After analysis, a new polynomial fit equation was used to determine the temperature sensitivities for the Er /Yb co-doped PbZrTiO phosphor in lieu of the conventional Boltzmann equation. The polynomial fit equation eliminated the dependency of the sensitivity on the inverse of the FIR factor and a flat sensitivity curve was obtained with temperature.
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http://dx.doi.org/10.1002/bio.4354 | DOI Listing |
Micromachines (Basel)
January 2025
School of Mechanical Engineering and Rail Transit, Changzhou University, Changzhou 213164, China.
This study analyzes the impact of slip-dependent zeta potential on the heat transfer characteristics of nanofluids in cylindrical microchannels with consideration of thermal radiation effects. An analytical model is developed, accounting for the coupling between surface potential and interfacial slip. The linearized Poisson-Boltzmann equation, along with the momentum and energy conservation equations, is solved analytically to obtain the electrical potential field, velocity field, temperature distribution, and Nusselt number for both slip-dependent (SD) and slip-independent (SI) zeta potentials.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei, 430072, P. R. China.
Phonon modal nonequilibrium is believed to widely exist around nanoscale hotspots, which can significantly affect the performance of nano-electronic and optoelectronic devices. However, such a phenomenon has not been explicitly observed in 3D device semiconductors at the nanoscale. Here, by employing a tip-enhanced Raman thermal measurement approach, substantial phonon nonequilibrium in gallium nitride near sub-10 nm laser-excited hotspots is directly revealed for the first time.
View Article and Find Full Text PDFEntropy (Basel)
January 2025
School of Mathematics, Southwestern University of Finance and Economics, Chengdu 611130, China.
A kinetic exchange model is developed to investigate wealth distribution in a market. The model incorporates a value function that captures the agents' psychological traits, governing their wealth allocation based on behavioral responses to perceived potential losses and returns. To account for the impact of transaction frequency on wealth dynamics, a non-Maxwellian collision kernel is introduced.
View Article and Find Full Text PDFJ Phys Condens Matter
January 2025
South China Normal University, School of Physics, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangzhou, 510631, CHINA.
With the continuous development of digital information and big data technologies, the ambient temperature and heat generation during the operation of magnetic storage devices play an increasingly crucial role in ensuring data security and device stability. In this study, we examined the lattice thermal conductivity of the van der Waals magnetic semiconductor CrSBr from bulk to monolayer structures using first-principles calculations and the phonon Boltzmann transport equation. Our results indicated that lattice thermal conductivity show anisotropy and CrSBr bilayer exhibits lower thermal conductivity at all temperatures.
View Article and Find Full Text PDFNanoscale
January 2025
Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China.
Superlattices are significant means to reduce the lattice thermal conductivity of thermoelectric materials and optimize their performance. In this work, using high-precision first-principles based neural network potentials combined with non-equilibrium molecular dynamics simulations and the phonon Boltzmann transport equation, the lattice thermal conductivities of BiTe monolayer and lateral BiTe/SbTe monolayer superlattices are thoroughly investigated. As the period length increases, the thermal conductivity shows a trend of an initial decrease followed by an increase, which aligns with conventional observations.
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