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Papers by J. Rojo
Solid State Ionics, 2005
... Auteur(s) / Author(s). LAZARRAGA MG ; PICO F. ; AMARILLA JM ; ROJAS RM ; ROJO JM ; Résumé / A... more ... Auteur(s) / Author(s). LAZARRAGA MG ; PICO F. ; AMARILLA JM ; ROJAS RM ; ROJO JM ; Résumé / Abstract. ... Fluorite-type oxides. ; Solid electrolytes. ; Localisation / Location. INIST-CNRS,Cote INIST : 18305, 35400013182903.0180. Nº notice refdoc (ud4) : 17081175. ...
Journal of Thermal Analysis and Calorimetry, 2007
Chromium doped spinels LiCr Y Mn 2-Y O 4 (0.2£Y£0.8) has been synthesized by the sucrose-aided co... more Chromium doped spinels LiCr Y Mn 2-Y O 4 (0.2£Y£0.8) has been synthesized by the sucrose-aided combustion procedure. The thermal behaviour, phase homogeneity and structural characteristics of the samples were studied by thermal analysis, coupled mass spectrometry, and room-and high-temperature X-ray diffraction methods. It was found that the 'as prepared' samples contained residual organic impurities undetectable for X-ray diffraction, that burn out completely at 400°C. Samples treated between 400 and 750°C are single phase spinels, whose crystallites size increase from 10 to 50 nm on increasing the temperature. Cr-doping enhances the thermal stability of the spinels, which augments on increasing the Cr content Y. The enhanced thermal stability of the spinels has been accounted for based on the high excess stabilization energy of Cr 3+ in octahedral ligand field.
Journal of The Electrochemical Society, 2012
Carbon nanocoils (CNCs) are coiled carbon nanofibers of ca. 10 nm in fiber diameter, and 10-20 nm... more Carbon nanocoils (CNCs) are coiled carbon nanofibers of ca. 10 nm in fiber diameter, and 10-20 nm in internal coil diameter. They are prepared through several oxidation treatments, which lead to a graduate content in surface oxygen groups evolving as either CO or CO 2 in temperature-programmed desorption. The CNCs show a moderate surface area (40-240 m 2 g −1 ) and a relatively high electrical conductivity (0.1-0.2 S cm −1 ). Some CNCs are activated to develop surface area. The electrochemical behaviour of CNCs as supercapacitor electrode is studied in the electrolytes H 2 SO 4 and Et 4 NBF 4 . From the parameters C 1 (overall specific capacitance measured at 1 mA cm −2 ), S BET (BET specific surface area), and CO and CO 2 content, the plots of C 1 /S BET vs. CO/S BET and vs. CO 2 /S BET are analyzed. In the acidic electrolyte, the oxygen groups evolving as CO 2 contribute significantly to enhance C 1 in addition to the groups evolving as CO. C 1 /S BET shows a linear dependence, with high slope, on CO 2 /S BET , and an exponential dependence on CO/S BET . In the organic electrolyte, the two kinds of oxygen groups contribute less to C 1 . The specific pseudocapacitance and double layer capacitance are determined and discussed in relation to the CO and CO 2 content and the S BET value.
Solid State Ionics, 2005
... Auteur(s) / Author(s). LAZARRAGA MG ; PICO F. ; AMARILLA JM ; ROJAS RM ; ROJO JM ; Résumé / A... more ... Auteur(s) / Author(s). LAZARRAGA MG ; PICO F. ; AMARILLA JM ; ROJAS RM ; ROJO JM ; Résumé / Abstract. ... Fluorite-type oxides. ; Solid electrolytes. ; Localisation / Location. INIST-CNRS,Cote INIST : 18305, 35400013182903.0180. Nº notice refdoc (ud4) : 17081175. ...
Journal of Thermal Analysis and Calorimetry, 2007
Chromium doped spinels LiCr Y Mn 2-Y O 4 (0.2£Y£0.8) has been synthesized by the sucrose-aided co... more Chromium doped spinels LiCr Y Mn 2-Y O 4 (0.2£Y£0.8) has been synthesized by the sucrose-aided combustion procedure. The thermal behaviour, phase homogeneity and structural characteristics of the samples were studied by thermal analysis, coupled mass spectrometry, and room-and high-temperature X-ray diffraction methods. It was found that the 'as prepared' samples contained residual organic impurities undetectable for X-ray diffraction, that burn out completely at 400°C. Samples treated between 400 and 750°C are single phase spinels, whose crystallites size increase from 10 to 50 nm on increasing the temperature. Cr-doping enhances the thermal stability of the spinels, which augments on increasing the Cr content Y. The enhanced thermal stability of the spinels has been accounted for based on the high excess stabilization energy of Cr 3+ in octahedral ligand field.
Journal of The Electrochemical Society, 2012
Carbon nanocoils (CNCs) are coiled carbon nanofibers of ca. 10 nm in fiber diameter, and 10-20 nm... more Carbon nanocoils (CNCs) are coiled carbon nanofibers of ca. 10 nm in fiber diameter, and 10-20 nm in internal coil diameter. They are prepared through several oxidation treatments, which lead to a graduate content in surface oxygen groups evolving as either CO or CO 2 in temperature-programmed desorption. The CNCs show a moderate surface area (40-240 m 2 g −1 ) and a relatively high electrical conductivity (0.1-0.2 S cm −1 ). Some CNCs are activated to develop surface area. The electrochemical behaviour of CNCs as supercapacitor electrode is studied in the electrolytes H 2 SO 4 and Et 4 NBF 4 . From the parameters C 1 (overall specific capacitance measured at 1 mA cm −2 ), S BET (BET specific surface area), and CO and CO 2 content, the plots of C 1 /S BET vs. CO/S BET and vs. CO 2 /S BET are analyzed. In the acidic electrolyte, the oxygen groups evolving as CO 2 contribute significantly to enhance C 1 in addition to the groups evolving as CO. C 1 /S BET shows a linear dependence, with high slope, on CO 2 /S BET , and an exponential dependence on CO/S BET . In the organic electrolyte, the two kinds of oxygen groups contribute less to C 1 . The specific pseudocapacitance and double layer capacitance are determined and discussed in relation to the CO and CO 2 content and the S BET value.