title: Direct observation of morphological evolution of a catalyst during carbon nanotube forest growth: new insights into growth and growth termination.
abstract: In this study, we develop a new methodology for transmission electron microscopy (TEM) analysis that enables us to directly investigate the interface between carbon nanotube (CNT) arrays and the catalyst and support layers for CNT forest growth without any damage induced by a post-growth TEM sample preparation. Using this methodology, we perform in situ and ex situ TEM investigations on the evolution of the morphology of the catalyst particles and observe the catalyst particles to climb up through CNT arrays during CNT forest growth. We speculate that the lifted catalysts significantly affect the growth and growth termination of CNT forests along with Ostwald ripening and sub-surface diffusion. Thus, we propose a modified growth termination model which better explains various phenomena related to the growth and growth termination of CNT forests.
authors.affiliation: Institute of Advanced Composite Materials, Korea Institute of Science and Technology, Jeonbuk 565-905, Republic of Korea. seungmin.kim@kist.re.kr and Department of Organic Materials and Fiber Engineering, Chonbuk National University, Jeonbuk 561-756, Republic of Korea.
authors.forename: Seojeong
authors.initials: S
authors.lastname: Jeong
authors.affiliation: Institute of Advanced Composite Materials, Korea Institute of Science and Technology, Jeonbuk 565-905, Republic of Korea. seungmin.kim@kist.re.kr.
authors.forename: Jaegeun
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Organic Materials and Fiber Engineering, Chonbuk National University, Jeonbuk 561-756, Republic of Korea.
authors.forename: Hwan-Chul
authors.initials: HC
authors.lastname: Kim
authors.affiliation: Institute of Advanced Composite Materials, Korea Institute of Science and Technology, Jeonbuk 565-905, Republic of Korea. seungmin.kim@kist.re.kr.
authors.forename: Jun Yeon
authors.initials: JY
authors.lastname: Hwang
authors.affiliation: Institute of Advanced Composite Materials, Korea Institute of Science and Technology, Jeonbuk 565-905, Republic of Korea. seungmin.kim@kist.re.kr.
authors.forename: Bon-Cheol
authors.initials: BC
authors.lastname: Ku
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11733, USA.
authors.forename: Dmitri N
authors.initials: DN
authors.lastname: Zakharov
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433, USA.
authors.forename: Benji
authors.initials: B
authors.lastname: Maruyama
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11733, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Stach
authors.affiliation: Institute of Advanced Composite Materials, Korea Institute of Science and Technology, Jeonbuk 565-905, Republic of Korea. seungmin.kim@kist.re.kr.
authors.forename: Seung Min
authors.initials: SM
authors.lastname: Kim