This thesis presents experimental and related theoretical studies of single layer graphene, bilayer graphene and single walled carbon nanotubes. The thesis is divided into three parts; the first part describes the phonon renormalization due to doping in two dimensional graphene and one dimensional carbon nanotubes. In the recent years, there is a tremendous interest both experimentally and theoretically, in the issues related to electron-phonon coupling in nanotubes and graphene. Theoretically, it is expected that the presence of Kohn anomalies in graphene and metallic nanotubes will result in significant changes in the self energy of phonons due to doping. In particular, with Fermi energy shift how the blockage of phonon decay (due to Pauli Exclusion Principle) into electron-hole excitations changes the phonon frequencies as well as its life time have been studied in details in the first part of the thesis. Since in graphene and metallic nanotubes, the momentum relaxation time of electrons is comparable to the phonon pulsation time, the phonon cannot be treated as a static perturbation and hence non-adiabatic effects are taken into account using time dependent perturbation theory. Electron-phonon coupling constant is also a key parameter to understand the mobility of carrier due to electron scattering by optical phonons at room temperature and limitation of the maximum current carrying capacity of graphene and nanotubes. All these parameters are determined in the first part of the thesis by performing in-situ transport and Raman measurements on graphene and nanotubes based field effect transistors. The second part of the thesis deals with the interaction of bio-molecules (nucleobases) with the nanotubes and graphene. The binding energies of various nucleobases with nanotubes and graphene have been calculated theoretically using quantum chemical and classical force field calculations, and experimentally from isothermal titration (micro) calorimetry. In this part we also present an experimental study on the dynamics of water confined inside the carbon nanotubes. Proton nuclear magnetic resonance studies have been used to probe the freezing and dynamics of the confined water inside 1.4 nm diameter single walled carbon nanotubes. We have observed that the confined water does not freeze up to 223K. The dynamics of confined water has been studied using pulsed field gradient technique. The decay of spin echo intensity as a function of gradient field shows characteristic features of water confined in unidimensional channels. From the decay profiles the mean squared displacement of water molecules is obtained for different diffusive times, showing an unambiguous evidence of single file diffusion of water molecules inside the nanotubes i.e mean squared displacement varying as square root of time. In the last part, we have developed carbon nanotube based vibration sensor and accelerometer to detect the vibrations of liquid and solid, respectively, using the property of voltage generation in nanotubes due to liquid flow.

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Les propriétés physiques d’un matériau sont intimement liées à sa structure cristalline et dans le cas d’ions dopants aux sites qu’ils occupent. La première partie de ce travail est dédiée au matériau diphosphate de sodium et de zinc Na2ZnP2O7, cristallisé out vitreux et ceci pour les ions dopants Co2+, Ni2+, Mn2+ et Eu3+. Les phases cristallisées ont été obtenues par la méthode Czochralski, les verres par trempe à partir de l’état fondu. Un ensemble de caractéristiques physiques ont été mises en jeu (Raman, infrarouge, RPE, absorption optique, luminescence) pour déterminer les sites occupés par les ions dopants et l’influence sur les propriétés optiques. La deuxième partie de cet travail consiste à une meilleure connaissance des matériaux diélectriques sans plomb appartenant à la famille pérovskite et plus particulièrement à la solution solide NaNbO3-BaTiO3. Des monocistaux ont été obtenus par la méthode des flux et caractérisés en utilisant plusieurs techniques : diffraction X, microanalyse, évolution thermique des domaines ferroélectriques-ferroélastiques, mesures diélectriques, piézoélectriques et pyroélectriques. / Abstract The physical properties of a material are intimately related to its crystalline structure and in the case of doped ions they are dependent on to the sites they occupy. The first part of this work is dedicated to the diphosphate material of sodium and zinc Na2ZnP2O7, glassy and crystallized for doped ions of Co2+, Ni2+, Mn2+ and Eu3+. The crystallized phases were obtained by the Czochralski method whereas the glasses were obtained by quenching from the molten state. A set of physical characteristics were studied (Raman, infrared, EPR, optical absorption, luminescence) to determine the sites occupied by the doped ions and its influence on the optical properties. The second part of this work consists of a better knowledge of lead-free dielectric materials belonging to the family of Perovskite, more particularly to NaNbO3-BaTiO3 solid solution. Single crystals were obtained by the flux method and were characterized using several techniques: X-rays diffraction, microanalysis, thermal evolution of ferroelectric and ferroelastic domains; dielectric, piezoelectric and pyroelectric measurements.