• K.SONAMUTHU
• GEENA VIDYA . S

The prime application of Nano technology is High temperature superconductor. The normal state and superconducting properties are believed to arise from the strongly correlated motion of the electronic charge carries (electrons or holes) in the CuO2 planes that essentially define the layered Cuprate HTSC. The other cations and oxygen atom in the structure provides structural stability and control the number of charge carries in the CuO2 planes. The Raman spectroscopy of HTSC explains that the role played by the phonons in the mechanism of superconductivity in the perovskite family of superconductors is not fully understood although a large series of experimental results has shown considerable coupling of some phonons to electronic excitation in these systems. Optical spectroscopy and especially Raman and Infrared spectroscopy revealed strong direct influences of the changes in the electronic states to the phonon at the center of the Brillouin. The lattice dynamics method is suited to determine the phonon frequencies in the proximity of the Brillouin zone centre only. But , the force constants obtained from that analysis do not provide a stable dynamics throughout the Brillouin zone. However, it is indispensable to have a precise knowledge of the zone –boundary phonons to investigate the contribution of electron-phonon coupling to Tc which can be achieved by neutron scattering techniques. The most commonly employed model is the valence force field model for computing phonon frequencies based on stretching bond and bending bond coordinates. Such models have the advantage of being well adopted to describe a covalent bonding but ignored the long–range Coulomb forces and wave vector dependence of the phonon spectrum. This work considered only the q=o modes and the number of model parameters exceeded the number of experimental data. The rigid ion model on the other hand considers both the short-range repulsive interactions and the long range Coulomb interaction among various rigid ions in the crystal..

Key words: Superconductor, Raman spectroscopy, Infrared symmetry, Brillouin, Three Body Force Shell Model, Phonon frequency, Lattice Dynamical Calculation, PED, etc.,

"Comparative Studies of Phonon Frequency Spectrum of HTSCs GdBa2Cu3O7 and SmBa2Cu3O7 Through Lattice Dynamics", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.11, Issue 3, page no.i653-i660, March-2024, Available :http://www.jetir.org/papers/JETIR2403884.pdf

"Comparative Studies of Phonon Frequency Spectrum of HTSCs GdBa2Cu3O7 and SmBa2Cu3O7 Through Lattice Dynamics", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.11, Issue 3, page no. ppi653-i660, March-2024, Available at : http://www.jetir.org/papers/JETIR2403884.pdf