Transmission Electron Microscopy and High-Resolution Transmission Electron Microscopy Study of Nanostructure and Metastable Phase Evolution in Pulsed-Laser-Ablation–Deposited Ti–Si Thin Film

Abstract

Thin films with a nominal composition close to Ti62.5Si37.5 were deposited on NaCl substrate at room temperature by pulsed laser ablation to study the evolution of the intermetallic compound Ti5Si3 using a combination of high-resolution and in situ transmission electron microscopy. The as-deposited amorphous films contain Ti-rich clusters, which influence the phase evolution and the decomposition behavior of the amorphous film. These clusters influence the nucleation of a metastable fcc Ti solid solution (ao = 0.433 nm) with composition richer in Ti than Ti62.5Si37.5 as the first phase to crystallize at 773 K. The Ti5Si3 nanocrystals form later, and even at 1073 K they coexist with fine fcc Ti-rich nanocrystals. Subsequent Ar+ ion-milling of the crystallized film results in a loss of silicon. The composition change leads to the dissolution of the Ti5Si3 nanocrystals and evolution of a new metastable Ti-rich fcc phase (ao= 0.408 nm).

Microstructural evolution in laser-ablation-deposited Fe–25 at.% Ge thin film

“…The formation of coatings and thin films using pulsed laser ablation process is increasingly gaining importance. [1][2][3][4] The rapid superheating at the subsurface due to coupling and transfer of energy from the laser beam to the target materials leads to catastrophic vaporization and explosion resulting in generation of atomized droplets in addition to the vapor plasma. The vapor plasma and the liquid droplets move at high speed (∼10-100 ms −1 ) 5 and are quenched on a suitably positioned substrate.…”

Microstructural evolution and metastable phase formation in laser ablation-deposited films of Fe-rich Fe–Ge intermetallic compounds

“…Pulsed laser ablation (PLD) is a versatile technique for depositing thin film of metals, alloys and ceramics [1][2][3][4][5][6][7][8]. The process primarily involves quenching of matter from vapour and plasma on a substrate by striking a high-power pulsed laser beam on a target [9].…”

“…Furthermore, plasma generated during this process often contains charged clusters. It has been shown recently that these clusters can modify the nature of the initial amorphous condensate and, hence, crystallization pathways [7]. Therefore, vapour quenching using laser ablation technique provides a unique opportunity to study the evolution of metastable phases and microstructures.…”