Page 81 - Synthesis of Functional Nanoparticles Using an Atmospheric Pressure Microplasma Process - LiangLiang Lin

Titanium Nitride Nanoparticles Synthesis - an Advanced Model Study towards Nitride Nanomaterial
(a)
(b)
Ti 2p
Ti 2p3/2 (458.4 eV)
Ti 2p3/2 (454.9 eV)
(c) N 1s
TiN (396.2 eV)
1200
1000 800 600 400
Binding energy (eV)
200 0
398.8 eV
Ti 2p
(464.4 eV) 1/2
Intensity (a.u.)
Intensity (a.u.)
Ti3p O2s
Intensity (a.u.) CKLL
N1s C1s
TiLMM
NKLL OKLL
Ti2s
O1s Ti2p
Ti 2p (460.6 eV) 1/2
470 468 466 464 462 460 458 456 454 452 403 402 401 400 399 398 397 396 395 394 393 Binding energy (eV) Binding energy (eV)
Figure 4.7 (a) Full XPS spectrum of NPs prepared at the condition 1; (b) XPS spectrum of Ti 2p; (c) XPS spectrum of N 1s
4.4 Process Analysis and Discussion
Plasma-assisted chemical dissociation is a complex process involving reactive radicals and electrons, initiated and driven by consecutive as well as parallel reactions such as electron impact process, Penning and charge transfer processes. Figure 4.8 illustrates a hypothesized mechanism for producing TiN nanoparticles by the microplasma process. Briefly, once transported into the plasma, TiCl4 vapors (Ti-Cl bond dissociation energy 4.47 eV 37) are dissociated by electrons and highly reactive species such as excited metastable Ar atoms (Ar*), excited nitrogen molecules N2*, or ionized Ar (Ar+), thus atomic Ti or ionized Ti moieties are formed in the plasma volume, which were detected and verified by the OES spectra. Similarly atomic N radicals were also generated in the plasma zone. The recombination reactions among Ti moieties and N radicals, followed by the nucleation and growth process, eventually lead to the formation of TiN nanoparticles.
69
400.9 eV