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 Ni2þ ions, belongingtoNiCl2 formed duringtheCl-basedpurification process.Inparticular,NiCl2 compound appearsunderdifferentmagnetic/crystallinephases:paramagneticordiamagnetic,orwell intercalatedinbetweencarbonsheetswithanorderedmagneticphaseatlowtemperature
Magnetism for understanding catalyst analysis of purified carbon nanotubes
Lamura G;
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 Ni2þ ions, belongingtoNiCl2 formed duringtheCl-basedpurification process.Inparticular,NiCl2 compound appearsunderdifferentmagnetic/crystallinephases:paramagneticordiamagnetic,orwell intercalatedinbetweencarbonsheetswithanorderedmagneticphaseatlowtemperatureI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
