{"title":"Positron Spectroscopy Study of Structural Defects and Electronic Properties of Carbon Nanotubes","authors":"E. Tsapko, I. Galstian","doi":"10.15407/ufm.21.02.153","DOIUrl":null,"url":null,"abstract":"The advantages and restrictions of different positron spectroscopy methods in the study of electronic properties of multilayer carbon nanotubes (MWCNTs) with metallic and semiconductor types of conductivity are considered. The defects’ influence on the parameters of the MWCNTs’ electronic structure is established via method of the angular correlation of annihilation radiation (ACAR). Analysis of the results shows that annihilation occurs with both σ -electrons (within the interlayer intervals), quasi-free electrons, and electrons of unsaturated covalent bonds. As determined, the increase in the defects’ concentration results to an increase in the radius of localization of the electron wave function ( r m 1 ) within the interlayer inter-vals and to an increase in the quasi-free electron concentration. Due to the formation of edge dislocations in the MWCNTs, the doubling of r m 1 (up to 0.25 nm), the hybridization of unsaturated and stretched σ -bonds, and, as a consequence, the increase of the concentration of conduction electrons occurs. The high sensitivity of the positrons to defects can be used to develop methods of MWCNTs’ attestation and defect identification; the 2 r mb , 2 r mi , and R values obtained from the ACAR spectra are the thickness of the layer, the interlayer distance, and the effective radius of free volume of the MWCNTs, respectively. ñòè. Ìåòîäîì óãëîâîé êîððåëÿöèè àííèãèëÿöèîííîãî èçëó÷åíèÿ (ÓÊÀÈ) óñòàíîâëåíî âëèÿíèå äåôåêòîâ íà ïàðàìåòðû ýëåêòðîííîé ñòðóêòóðû ÌÓÍÒ. Àíàëèç ðåçóëüòàòîâ ïîêàçàë, ÷òî àííèãèëÿöèÿ ïðîèñõîäèò ñ σ -ýëåêòðîíàìè (â ìåæñëîåâûõ ïðîìåæóòêàõ), ñ êâàçèñâîáîäíûìè ýëåêòðîíàìè è ñ ýëåêòðîíàìè íåíàñûùåííûõ êîâàëåíòíûõ ñâÿçåé. Ïîêàçàíî, ÷òî ðîñò êîíöåíòðàöèè äåôåêòîâ ïðèâî-äèò ê óâåëè÷åíèþ ðàäèóñà ëîêàëèçàöèè âîëíîâîé ôóíêöèè ýëåêòðîíîâ ( r m 1 ) â ìåæñëîåâûõ ïðîìåæóòêàõ è ðîñòó äîëè êâàçèñâîáîäíûõ ýëåêòðîíîâ. Âñëåäñòâèå îáðàçîâàíèÿ êðàåâûõ äèñëîêàöèé â ÌÓÍÒ ïðîèñõîäÿò óäâàèâàíèå r m 1 (äî 0,25 íì), ãèáðèäèçàöèÿ íåíàñûùåííûõ è ðàñòÿíóòûõ σ -ñâÿçåé è, êàê ñëåäñòâèå, ðîñò êîíöåíòðàöèè ýëåêòðîíîâ ïðîâîäèìîñòè. Âûñîêàÿ ÷óâñòâèòåëüíîñòü ïîçèòðîíîâ ê äåôåêòàì ìîæåò áûòü èñïîëüçîâàíà äëÿ ðàçðàáîòêè ìåòîäîâ àòòåñòàöèè ÌÓÍÒ è èäåíòèôèêàöèè äåôåêòîâ; âåëè÷èíû 2 r mb , 2 r mi è R , ïîëó÷åííûå èç ñïåêòðîâ","PeriodicalId":41786,"journal":{"name":"Uspekhi Fiziki Metallov-Progress in Physics of Metals","volume":null,"pages":null},"PeriodicalIF":1.5000,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"5","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Uspekhi Fiziki Metallov-Progress in Physics of Metals","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.15407/ufm.21.02.153","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 5
Abstract
The advantages and restrictions of different positron spectroscopy methods in the study of electronic properties of multilayer carbon nanotubes (MWCNTs) with metallic and semiconductor types of conductivity are considered. The defects’ influence on the parameters of the MWCNTs’ electronic structure is established via method of the angular correlation of annihilation radiation (ACAR). Analysis of the results shows that annihilation occurs with both σ -electrons (within the interlayer intervals), quasi-free electrons, and electrons of unsaturated covalent bonds. As determined, the increase in the defects’ concentration results to an increase in the radius of localization of the electron wave function ( r m 1 ) within the interlayer inter-vals and to an increase in the quasi-free electron concentration. Due to the formation of edge dislocations in the MWCNTs, the doubling of r m 1 (up to 0.25 nm), the hybridization of unsaturated and stretched σ -bonds, and, as a consequence, the increase of the concentration of conduction electrons occurs. The high sensitivity of the positrons to defects can be used to develop methods of MWCNTs’ attestation and defect identification; the 2 r mb , 2 r mi , and R values obtained from the ACAR spectra are the thickness of the layer, the interlayer distance, and the effective radius of free volume of the MWCNTs, respectively. ñòè. Ìåòîäîì óãëîâîé êîððåëÿöèè àííèãèëÿöèîííîãî èçëó÷åíèÿ (ÓÊÀÈ) óñòàíîâëåíî âëèÿíèå äåôåêòîâ íà ïàðàìåòðû ýëåêòðîííîé ñòðóêòóðû ÌÓÍÒ. Àíàëèç ðåçóëüòàòîâ ïîêàçàë, ÷òî àííèãèëÿöèÿ ïðîèñõîäèò ñ σ -ýëåêòðîíàìè (â ìåæñëîåâûõ ïðîìåæóòêàõ), ñ êâàçèñâîáîäíûìè ýëåêòðîíàìè è ñ ýëåêòðîíàìè íåíàñûùåííûõ êîâàëåíòíûõ ñâÿçåé. Ïîêàçàíî, ÷òî ðîñò êîíöåíòðàöèè äåôåêòîâ ïðèâî-äèò ê óâåëè÷åíèþ ðàäèóñà ëîêàëèçàöèè âîëíîâîé ôóíêöèè ýëåêòðîíîâ ( r m 1 ) â ìåæñëîåâûõ ïðîìåæóòêàõ è ðîñòó äîëè êâàçèñâîáîäíûõ ýëåêòðîíîâ. Âñëåäñòâèå îáðàçîâàíèÿ êðàåâûõ äèñëîêàöèé â ÌÓÍÒ ïðîèñõîäÿò óäâàèâàíèå r m 1 (äî 0,25 íì), ãèáðèäèçàöèÿ íåíàñûùåííûõ è ðàñòÿíóòûõ σ -ñâÿçåé è, êàê ñëåäñòâèå, ðîñò êîíöåíòðàöèè ýëåêòðîíîâ ïðîâîäèìîñòè. Âûñîêàÿ ÷óâñòâèòåëüíîñòü ïîçèòðîíîâ ê äåôåêòàì ìîæåò áûòü èñïîëüçîâàíà äëÿ ðàçðàáîòêè ìåòîäîâ àòòåñòàöèè ÌÓÍÒ è èäåíòèôèêàöèè äåôåêòîâ; âåëè÷èíû 2 r mb , 2 r mi è R , ïîëó÷åííûå èç ñïåêòðîâ
期刊介绍:
The review journal Uspehi Fiziki Metallov (abbreviated key-title: Usp. Fiz. Met.) was founded in 2000. In 2018, the journal officially obtained parallel title Progress in Physics of Metals (abbreviated title — Prog. Phys. Met.). The journal publishes articles (that has not been published nowhere earlier and are not being considered for publication elsewhere) comprising reviews of experimental and theoretical results in physics and technology of metals, alloys, compounds, and materials that possess metallic properties; reviews on monographs, information about conferences, seminars; data on the history of metal physics; advertising of new technologies, materials and devices. Scope of the Journal: Electronic Structure, Electrical, Magnetic and Optical Properties; Interactions of Radiation and Particles with Solids and Liquids; Structure and Properties of Amorphous Solids and Liquids; Defects and Dynamics of Crystal Structure; Mechanical, Thermal and Kinetic Properties; Phase Equilibria and Transformations; Interphase Boundaries, Metal Surfaces and Films; Structure and Properties of Nanoscale and Mesoscopic Materials; Treatment of Metallic Materials and Its Effects on Microstructure and Properties.