Study of the structure of titanium thin films deposited with a vacuum arc as a function of the thickness

Fazio, M.; Vega, Daníel; Kleiman, A; Colombo, Diego Alejandro; Arias, Lina María Franco; Márquez, A.

doi:10.1016/j.tsf.2015.09.015

Cited by 23 publications

(13 citation statements)

References 17 publications

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“…This critical thickness was dependent on the substrate surface orientation and temperature, which was maximized at 500°C on a {110} surface. These findings, as well as additional deposited thin film studies, indicate that the criteria for FCC Ti stability are related to film thickness, surface orientation, and temperature [6][7][8][9][10][11]. FCC Ti has also been widely observed in Ti-Al, -Ni, and -Ag multilayer films, where it was found that an HCP to FCC transformation occurred during cross-sectional ion-milling/thinning of the multilayer for TEM studies.…”

Section: Introductionmentioning

confidence: 64%

In situ TEM observation of FCC Ti formation at elevated temperatures

Kacher

Gammer

et al. 2017

Scripta Materialia

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Pure Ti traditionally exhibits the hexagonal closed packed (HCP) crystallographic structure under ambient conditions and the body centered cubic (BCC) structure at elevated temperatures. In addition to these typical structures for Ti alloys, the presence of a face centered cubic (FCC) phase associated with thin films, interfaces, or high levels of plastic deformation has occasionally been reported. Here we show that small FCC precipitates form in freestanding thin foils during in situ transmission electron microscope (TEM) heating and we discuss the potential origins of the FCC phase in light of the in situ observations. This FCC phase was found to be stable upon cooling and under ambient conditions, which allowed us to explore its mechanical properties and stability via nanomechanical in situ TEM testing. It was found that FCC platelets within the HCP matrix phase were stable under mechanical deformation and exhibited similar mechanical deformation behavior as the parent HCP phase.

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Section: Introductionmentioning

confidence: 64%

In situ TEM observation of FCC Ti formation at elevated temperatures

Kacher

Gammer

et al. 2017

Scripta Materialia

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“…Although the ground-state of Ti at standard conditions has a hexagonal close-packed (hcp) structure, a number of studies showed the presence of a face-centered cubic (fcc) phase in thin films 47 . Moreover, an hcp-fcc transition may be caused by increased temperature 48 .…”

Section: Thermal Background and Film Thicknessmentioning

confidence: 99%

Attosecond screening dynamics mediated by electron localization in transition metals

et al. 2019

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Transition metals with their densely confined and strongly coupled valence electrons are key constituents of many materials with unconventional properties 1 , such as high-Tc superconductors, Mott insulators and transition-metal dichalcogenides 2 . Strong electron interaction offers a fast and efficient lever to manipulate their properties with light, creating promising potential for next-generation electronics 3-6 . However, the underlying dynamics is a fast and intricate interplay of polarization and screening effects, which is poorly understood. It is hidden below the femtosecond timescale of electronic thermalization, which follows the light-induced excitation 7 . Here, we investigate the many-body electron dynamics in transition metals before thermalization sets in. We combine the sensitivity of intra-shell transitions to screening effects 8 with attosecond time resolution to uncover the interplay of photo-absorption and screening. First-principles time-dependent calculations allow us to assign our experimental observations to ultrafast electronic localization on d-orbitals. The latter modifies the whole electronic structure as well as the collective dynamic response of the system on a timescale much faster than the light-field cycle. Our results demonstrate a possibility for steering the electronic properties of solids prior to electron thermalization, suggesting that the ultimate speed of electronic phase transitions is limited only by the duration of the controlling laser pulse. Furthermore, external control of the local electronic density serves as a fine tool for testing state-of-the art models of electron-electron interactions. We anticipate our study to facilitate further investigations of electronic phase transitions, laser-metal interactions and photo-absorption in correlated electron systems on its natural timescale.A characteristic thermalization time of laser-excited hot electrons in solids is in the femtosecond regime and becomes faster with stronger electron interactions 7 . Therefore, attosecond time resolution is required to resolve coupled electron dynamics during the lasermatter interaction before electron thermalization has occurred. Attosecond transient absorption spectroscopy revealed electric-field-guided electron dynamics in simple dielectrics and semiconductors 9-14 . However, transient absorption studies of localized and strongly interacting electrons, such as on d-and f-orbitals of transition metals, have been limited to the fewfemtosecond regime 15 . Transition metal elements are the key constituents of many materials exhibiting remarkable properties, such as Mott insulators, high-Tc superconductors and transition metal dichalcogenides 2 . Understanding the coupled-electron dynamics in these systems is central for their applications in optoelectronics, energy-efficient electronics, magnetic-memory devices, spintronics and new solar cells 16 . Transition metal elements were studied with attosecond photoemission spectroscopy [17][18][19] . However, state-of-the-art theoretical

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“…The XRD patterns of the single layer Ti coatings exhibited peaks related to the hexagonal close packed (hcp) Ti crystal structure, which is commonly denoted as α phase. On the other hand, the thinnest single layer Ti coating (Ti A, see Table 2) exhibited an additional peak which could be associated with the face centered cubic (fcc) Ti phase [19]. According to previous studies [19,20], the presence of the fcc Ti phase was found to be dependent on the film thickness.…”

Section: Substrates and Coatings Characteristicsmentioning

confidence: 79%

“…On the other hand, the thinnest single layer Ti coating (Ti A, see Table 2) exhibited an additional peak which could be associated with the face centered cubic (fcc) Ti phase [19]. According to previous studies [19,20], the presence of the fcc Ti phase was found to be dependent on the film thickness. The critical thickness above which no fcc Ti was observed was estimated in ~ 0.3 µm.…”

Section: Substrates and Coatings Characteristicsmentioning

confidence: 79%

Mechanical behavior of PVD coatings deposited on ADI

et al. 2019

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In this work, the mechanical behavior of the coated ADI system is studied. For this purpose, single layer Ti and bilayer Ti/TiN and TiAl/TiAlN coatings, with different thicknesses, were deposited by the PVD technique of cathodic arc deposition on high strength ADI substrates using industrial and experimental devices. The characterization of the coatings includes the measurement of the layer thicknesses by the spherical abrasion method, the determination of existing phases and residual stresses by x-ray diffraction and the evaluation of the surface topography using a stylus profilometer. The analysis of the mechanical properties of the coatings comprises the measurement of the surface hardness by micro indentation tests and the evaluation of the scratch resistance. The scratch tests were performed on a scratch tester equipped with a Rockwell indenter. A progressive load from 1 to 100 N, a load rate of 99 N/min, a speed of 5 mm/min and a scratch length of 5 mm were employed. The influence of the coatings characteristics on the scratch resistance of the coated samples and the friction coefficients obtained are evaluated. The results show that Ti coated samples had tensile residual stresses, the lowest surface hardness and the lowest critical loads for scratch adhesion strength. The samples coated with Ti/TiN and TiAl/TiAlN had highly compressive residual stresses and the highest critical loads, while the hardness was higher for TiAl/TiAlN. On the other hand, the evolution of the friction coefficient was similar for all the coated samples.

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Study of the structure of titanium thin films deposited with a vacuum arc as a function of the thickness

Cited by 23 publications

References 17 publications

In situ TEM observation of FCC Ti formation at elevated temperatures

In situ TEM observation of FCC Ti formation at elevated temperatures

Attosecond screening dynamics mediated by electron localization in transition metals

Mechanical behavior of PVD coatings deposited on ADI

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