Effect of Temperature Gradient Direction in the Catalyst Nanoparticle on CNTs Growth Mode

Table 1 Specimen designations and their deposition conditions by thermal CVD

Spec. desig. ^a	t^b (min)	Catalyst/substrate	Sub. surface condition ^c	Temp. ^d T _G/T _S (°C/°C)	ΔT ^e	CNTs growth mode
A1–5	5	Co/SBA-15	R	25/800	–	Base-growth
A1–10	10
A1–15	15
A1–20	20
A1–30	30
A1–40	40
A1–65	65
A1–90	90
A2–20	20	Co/Si (001)	S	25/800	–	Base-growth
A3–20	20	Co/SBA-15	R	800/600	+	Tip-growth
A4–20	20	Co/Si (001)	S	800/600	+	Tip-growth
A5–20	20	Co/SBA-15	R	650/650	~0	No CNTs
A6–5	5	Co/SBA-15	R	800/800	~0	No CNTs
A6–10	10
A6–15	15
A7–5	5	No cata./SBA-15	R	25/800	–	No CNTs
A7–10	10
A7–15	15
A8–5	5	No cata./SBA-15	R	800/800	~0	No CNTs
A8–15	15
A8–25	25

^a Other deposition conditions: H₂/C₂H₂ = 50/50 (sccm/sccm); 3 kPa pressure
^b t: CNTs deposition time
^c Conditions of the substrate surface, R Rough (porous) and S Smooth surface
^d T _G: the pre-heated temperature of the reaction gas; T _S: the substrate temperature at heating zone
^e∆T = temperature of catalyst at the top minus at the bottom. Its sign represents the temperature gradient direction