Open Quantum Matter-field Systems and Entropy | Chapter 5 | Current Research Progress in Physical Science Vol. 3

 

We consider a system of Fermions interacting with a coherent electromagnetic field and calculate the entropy dynamics. We obtain a negative term describing an entropy decrease depending on the electromagnetic field, which can cancel the positive term obtained according to the second law of thermodynamics. For the application of this theory to a semiconductor structure converting the environmental heat into coherent electromagnetic energy, we obtain a physical interpretation of the two processes, as field radiation by quantum transitions, and heat absorption by the Peltier effect.

 

Author(s) Details

Eliade Stefanescu
Center of Advanced Studies in Physics, Institute of Mathematics “Simion Stoilow” of the Romanian Academy, 21 Calea Grivitei, 010702 Bucharest, Romania.

 

Please see the book here: https://doi.org/10.9734/bpi/crpps/v3/1178

Study on Soft Phonons and Mode Grüneisen Parameters in a Framework Material H3[Co(CN)6] | Chapter 02 | Novel Perspectives of Engineering Research Vol. 1

 The author has spent the last several years researching phonons and their structure-properties relationships in a variety of advanced functional materials, including graphene, TiS3 nanosheet and nanofiber, VSe2 nanosheet, and SnO2 nanoparticles, as well as recently established low-dimensional 2D materials such as graphene, TiS3 nanosheet and nanofiber, VSe2 nanosheet, and SnO2 nanoparticles. The phonons and mode Grüneisen parameters of a flexible framework compound H3[Co(CN)6] are described in detail in this book chapter. H3[Co(CN)6] is a cyanide with a flexible framework structure and negative thermal expansion along the c-axis. Under hydrostatic pressure ranging from ambient to 11 GPa, in-situ high-pressure Raman spectroscopy experiments on H3[Co(CN)6] in a diamond-anvil cell were carried out. A phase transition from trigonal to monoclinic is identified at 2.3 GPa based on the evolution of Raman spectra, band splitting, and discontinuous changes in the pressure dependence of band frequencies. A lattice band at 140 cm-1 and the Co-CN deformation band at 348 cm-1, in contrast to other bands, softened with increasing pressure. The pressure dependence of Raman mode frequencies (d/dP) were used to calculate mode Grüneisen parameters (yi) for the ambient trigonal phase. As the molecule amorphized about 11 GPa, there was no Raman band with a flat spectral characteristic.

Author(S) Details

K. K. Mishra
Department of Physics, University of Puerto Rico, San Juan, PR 00925-2537, USA.

View Book:- https://stm.bookpi.org/NPER-V1/article/view/4359  

Study on Phonon Anharmonicity in a Framework Material H3[Co(CN)6] | Chapter 6 | New Innovations in Chemistry and Biochemistry Vol. 4

 The author has been studying phonons on functional materials for several years and has established structure-property correlations on flexible framework structure materials, lead free oxides, thin film perovskites, low dimensional 2D materials such as graphene nanosheets, TiS3 nanofiber, VSe2 nanosheets, SnO2 quasi nanoparticles, and other low dimensional 2D materials. Temperature dependent Raman spectroscopy experiments on the negative thermal expansion framework material H3[Co(CN)6] in the temperature range 80-300 K have been reported in this book chapter to elucidate the phonon anharmonicity of distinct phonons. There were no discontinuous or slope variations in phonon mode frequencies, linewidths, or band intensities, indicating that the compound remained stable across the temperature range studied. The temperature dependences of mode frequencies and their linewidths were investigated using phonon anharmonicity models. In this flexible molecule, the three-phonon decay mechanism was found to be more prevalent than the four-phonon decay process. In summary, the current research illustrates the anharmonicity of phonons and their impact on the thermal expansion of the H3[Co(CN)6] framework material.

Author (S) Details

K. K. Mishra
Department of Physics, University of Puerto Rico, San Juan, PR 00925-2537, USA.

View Book :- https://stm.bookpi.org/NICB-V4/article/view/4325