Data di Pubblicazione:
2016
Abstract:
The precisequantification ofcatalystresiduesinpurified carbonnanotubesisoftenamajorissueinview
of anyfundamentaland/orapplicativestudies.Moreimportantly,sincethebestCNTsaresuccessfully
grownwithmagneticcatalysts,theirquantification becomesstrictlynecessarytobetterunderstand
intrinsic propertiesofCNT.Forthesereasons,wehavedeeplyanalyzedthecatalystcontentremainedin
nickel-yttrium arc-dischargesinglewalledcarbonnanotubespurified bybothachlorine-gasphaseanda
standard acid-basedtreatment.ThestudyfocusesonNianalysiswhichhasbeeninvestigatedby
transmission electronmicroscopy,X-raydiffraction,thermogravimetryanalysis,andmagneticmea-
surements. Inthecaseoftheacid-basedtreatment,allquantifications resultinadecreaseofthena-
nocrystallized Nibyafactoroftwo.Inthecaseofthehalogengastreatment,analysisandquantification
of Nicontentislessstraightforward:ahugedifferenceappearsbetweenX-raydiffractionandthermo-
gravimetryresults.Thankstomagneticmeasurements,thisdisagreementisexplainedbythepresenceof
Ni2รพ ions, belongingtoNiCl2 formed duringtheCl-basedpurification process.Inparticular,NiCl2
compound appearsunderdifferentmagnetic/crystallinephases:paramagneticordiamagnetic,orwell
intercalatedinbetweencarbonsheetswithanorderedmagneticphaseatlowtemperature
Tipologia CRIS:
01.01 Articolo in rivista
Keywords:
Carbon nanotubes; Gas phase treatment; Magnetization; Purification; Spincrossover; Superparamagnetism
Elenco autori:
Lamura, Gianrico
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