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Matériaux fonctionnels carbonés
(17) Production(s) de l'année 2022
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Piezoelectricity and Related Properties in Orthorhombic Cadmium Diiodate 
Auteur(s): Azeroual H., Bantignies J.-L., Alvarez L., Maurin D., Granier D., Haines J., Cambon O., Hermet P.
(Article) Publié:
Journal Of Materials Chemistry C, vol. 10 p.9499-9511 (2022)
Texte intégral en Openaccess : 
Ref HAL: hal-03759175_v1
DOI: 10.1039/D2TC00769J
Exporter : BibTex | endNote
Résumé: We report a complete investigation of the structural, electronic, vibrational, elastic and piezoelectric properties of the P2 1 2 1 2 1 orthorhombic phase in cadmium diiodate (δ-Cd(IO 3) 2) by combining experiments and first-principles based calculations. We revisited the nature of the electronic band gap and suggest an indirect band gap with a value of 4.6 eV. The infrared and Raman responses were measured and the different phonon modes assigned. To date, the δ-Cd(IO 3) 2 piezoelectric response remains unknown. We reported the different mechanisms involved in its piezoelectric response from the density functional perturbation theory. The highest value of the piezoelectric-stress and piezoelectric-strain constants in the zero Kelvin limit is predicted for e 41 =-0.27 C/m 2 and d 41 =-10.32 pC/N. These sizable values associated with the thermal stability (no phase transition up to the thermal decomposition at 550°C) and a relative large electronic band gap make δ-Cd(IO 3) 2 a potential candidate for piezoelectric applications.
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Performance of Surface Plasmon Resonance Sensors Using Copper/Copper Oxide Films: Influence of Thicknesses and Optical Properties
Auteur(s): Barchiesi Dominique, Gharbi Tasnim, Cakir D., Anglaret E., Fréty Nicole, Kessentini Sameh, Maâlej Ramzi
(Article) Publié:
Photonics, vol. 9 p.104 (2022)
Texte intégral en Openaccess : 
Ref HAL: hal-03588847_v1
DOI: 10.3390/photonics9020104
Exporter : BibTex | endNote
Résumé: Surface plasmon resonance sensors (SPR) using copper for sensitive parts are a competitivealternative to gold and silver. Copper oxide is a semiconductor and has a non-toxic nature. Theunavoidable presence of copper oxide may be of interest as it is non-toxic, but it modifies thecondition of resonance and the performance of the sensor. Therefore, the characterization of theoptical properties of copper and copper oxide thin films is of interest. We propose a method torecover both the thicknesses and optical properties of copper and copper oxide from absorbancecurves over the(0.9; 3.5)eV range, and we use these results to numerically investigate the surfaceplasmon resonance of copper/copper oxide thin films. Samples of initial copper thicknesses 10, 30and 50 nm, after nine successive oxidations, are systematically studied to simulate the signal of aSurface Plasmon Resonance setup. The results obtained from the resolution of the inverse problem ofabsorbance are used to discuss the performance of a copper-oxide sensor and, therefore, to evaluatethe optimal thicknesses.
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Tuning of photoluminescence intensity and Fermi level position of individual single-walled carbon nanotubes by molecule confinement
Auteur(s): Chambard R., Moreno-López Juan Carlos, Hermet P., Sato Yuta, Suenaga Kazu, Pichler Thomas, Jousselme Bruno, Aznar R., Bantignies J.-L., Izard N., Alvarez L.
(Article) Publié:
Carbon, vol. 186 p.423-430 (2022)
Texte intégral en Openaccess :
Ref HAL: hal-03426915_v1
DOI: 10.1016/j.carbon.2021.09.072
Exporter : BibTex | endNote
Résumé: Photoluminescence of single-walled carbon nanotubes is monitored at the individual scale by molecule encapsulation into their hollow core. Depending on the electronic character (electron donor or acceptor) of the confined molecule, enhancement or quenching of the photoluminescence intensity is demonstrated. This behavior is assigned to a charge transfer, evidenced by the shift of the Raman G-band, and a correlated Fermi level shift shown by photoemission experiments. Our experimental results are supported by DFT calculations. A consistent picture of the physical interactions taking place in the hybrid systems and their effects on the optical and electronic properties is given. Our results indicate that the electron affinity or ionization potential of the encapsulated molecules and the diameter of the nanotube are relevant parameters to tune the light emission properties of the hybrid systems at the nanoscale.
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