Ab initio DFT calculations for the phonon dispersion (PD) and the phonon density of states (PDOS) of the two isotopic forms ((10)B and (11)B) of MgB2 demonstrate that use of a reduced symmetry super-lattice provides an improved approximation to the dynamical, phonon-distorted P6/mmm crystal structure. Construction of phonon frequency plots using calculated values for these isotopic forms gives linear trends with integer multiples of a base frequency that change in slope in a manner consistent with the isotope effect (IE). Spectral parameters inferred from this method are similar to that determined experimentally for the pure isotopic forms of MgB2. Comparison with AlB2 demonstrates that a coherent phonon decay down to acoustic modes is not possible for this metal. Coherent acoustic phonon decay may be an important contributor to superconductivity for MgB2.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1039/c4cp04114c | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Optical Phonon Decay and Improved Thermoelectric Efficiency in p-Type MgSb.
ACS Appl Mater Interfaces
January 2025
International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), IIT M Research Park, Chennai 600113, India.
The MgSb-based layered compounds exhibit exceptional thermoelectric properties over a wide temperature range and possess the potential to supplant traditional BiTe modules with reliable and economical MgSb-based thermoelectric devices, contingent upon the availability of a complementary p-type MgSb material with high thermoelectric efficiency comparable to that of n-type MgSb. We provide a simpler method involving the codoping of monovalent atoms (K and Na) at the Mg site of the MgSb lattice to improve the thermoelectric performance of p-type MgSb. K-Na codoping results in a peak power factor of around 0.
View Article and Find Full Text PDFRoom-Temperature, Strong Emission of Momentum-Forbidden Interlayer Excitons in Nanocavity-Coupled Twisted van der Waals Heterostructures.
Nano Lett
January 2025
Department of Materials Science and Engineering, Centre for Functional Photonics, and Hong Kong Branch of National Precious Metals Material Engineering Research Centre, City University of Hong Kong, Hong Kong S.A.R., 999077, China.
The emission efficiency of interlayer excitons (IEs) in twisted 2D heterostructures has long suffered from momentum mismatch, limiting their applications in ultracompact excitonic devices. Here, we report strong room-temperature emission of momentum-forbidden IE in 30°-twisted MoS/WS heterobilayers. Utilizing a plasmonic nanocavity, the Purcell effect boosts the IE emission intensity in the cavity by over 2 orders of magnitude.
View Article and Find Full Text PDFLattice thermal conductivity and phonon properties of polycrystalline graphene.
Nanoscale Adv
December 2024
Department of Mechanical Engineering, IIT Bombay Mumbai Maharashtra India 400076
Using the spectral energy density method, we predict the phonon scattering mean lifetimes of polycrystalline graphene (PC-G) having polycrystallinity only along the -axis with seven different misorientation (tilt) angles at room temperature. Contrary to other studies on PC-G samples, our results indicate a strong dependence of the thermal conductivity (TC) on the tilt angles which we attribute to careful preparation of our grain boundaries-based samples without introducing any local strains and ensuring periodic boundary conditions for the supercells along the and axes. We also show that the square of the group velocity components along and axes and the phonon lifetimes are uncorrelated and the phonon density of states are almost the same for all samples with different tilt angles.
View Article and Find Full Text PDFOptimizing Lasing Performance of CsPbBr Microplates by Regulating Exciton Recombination Dynamics with Pressure.
J Phys Chem Lett
December 2024
State Key Laboratory of Superhard Materials & College of Physics, Jilin University, Changchun 130012, China.
This study aims to achieve an ultralow lasing threshold in CsPbBr microplates (MPs), a crucial step toward developing electrically driven micro/nanolasers for optics integrated chips. We investigate the lasing behavior of CsPbBr MPs under varying pressures by using static-state photoluminescence (PL), time-resolved PL (TRPL), and first-principles theory calculations based on density functional theory (DFT). Our results reveal that the lasing threshold initially decreases and then increases, with a critical turning point at 0.
View Article and Find Full Text PDFYb-Doped Titanate-Germanate Glasses for Near-IR Luminescence Applications: Synthesis, Characterization, and the Influence of TiO Concentration.
Materials (Basel)
November 2024
Institute of Chemistry, University of Silesia, Szkolna 9 Street, 40-007 Katowice, Poland.
In the framework of luminescent rare-earth-doped glasses for near-infrared applications, TiO-containing inorganic glasses have been recently demonstrated to be a promising alternative to commercially used high-phonon SiO-based glasses. This study investigates the effect of TiO concentration on the near-infrared spectroscopic properties of Yb ions in multicomponent titanate-germanate glasses. A series of glass samples in the xTiO-(60-x)GeO-BaO-GaO-YbO system (x ranging from 0 to 50 mol%) were synthesized using the melt-quenching technique.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!