Editorial

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4 pages, 221 KiB

Open AccessEditorial

Structure and Phase Transformations in Thin Films

by Zsolt Czigány

Coatings 2023, 13(7), 1233; https://doi.org/10.3390/coatings13071233 - 11 Jul 2023

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Abstract

The field of thin films has gone through a great development in recent decades [...] Full article

(This article belongs to the Special Issue Structure and Phase Transformations in Thin Films)

Research

Jump to: Editorial

15 pages, 5366 KiB

Open AccessArticle

Phase Composition, Hardness, and Thermal Shock Properties of AlCrTiN Hard Films with High Aluminum Content

by Lijing Peng, Jun Zhang and Xiaoyang Wang

Coatings 2023, 13(3), 547; https://doi.org/10.3390/coatings13030547 - 03 Mar 2023

Cited by 2 | Viewed by 1172

Abstract

TiCrAlN hard films based on TiN or CrN show superior properties in terms of hardness, wear resistance, and thermal stability due to the addition of alloying elements. AlCrTiN films based on AlN may have higher thermal shock properties, but the knowledge of AlCrTiN [...] Read more.

TiCrAlN hard films based on TiN or CrN show superior properties in terms of hardness, wear resistance, and thermal stability due to the addition of alloying elements. AlCrTiN films based on AlN may have higher thermal shock properties, but the knowledge of AlCrTiN films with high Al content has been insufficient until now. In this study, two sets of AlCrTiN hard films with different Al contents of 48 at.% and 58 at.% among metal components were prepared via multi-arc ion plating so as to investigate the effect of Al content on the phase composition, hardness, and thermal shock resistance of the films. The same microstructures, morphologies, and thicknesses of the fabricated film samples were achieved by changing the combination of cathode alloy targets and adjusting the arc source current during deposition. The surface chemical composition, cross-sectional elemental distribution, microstructure, morphology, phase composition, surface hardness, film/substrate adhesion strength, and thermal shock performance of the AlCrTiN films were examined. The obtained results reveal that the two sets of AlTiCrN hard films are face-centered cubic solid solutions with a columnar fine grain structure and a preferred growth orientation of (200) crystal plane. The hardness of the AlCrTiN films can be improved up to HV2850 by properly reducing the Al content from 58 at.% to 48 at.%. Meanwhile, the film/substrate adhesion performance is strong enough in terms of critical loads greater than 200 N. Furthermore, the AlCrTiN films maintain high thermal shock resistance at 600 °C when the Al content decreases from 58 at.% to 48 at.%. The optimal composition of the AlCrTiN hard films is 25:13:15:47 (at.%), based on the consideration of hardness, adhesion, and thermal shock cycling resistance. This optimal AlCrTiN hard film can be suggested as an option for protective coatings of hot process die tools. Full article

(This article belongs to the Special Issue Structure and Phase Transformations in Thin Films)

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7 pages, 2624 KiB

Open AccessArticle

Raman Spectroscopy of V₄O₇ Films

by Petr Shvets, Ksenia Maksimova and Alexander Goikhman

Coatings 2022, 12(3), 291; https://doi.org/10.3390/coatings12030291 - 22 Feb 2022

Cited by 6 | Viewed by 1740

Abstract

A thin film of vanadium oxide Magnéli phase V₄O₇ was produced using cathodic arc sputtering. X-ray diffraction, Rutherford backscattering spectrometry and Raman investigations confirmed the formation of this phase. The Raman spectrum of V₄O₇ differs considerably from [...] Read more.

A thin film of vanadium oxide Magnéli phase V₄O₇ was produced using cathodic arc sputtering. X-ray diffraction, Rutherford backscattering spectrometry and Raman investigations confirmed the formation of this phase. The Raman spectrum of V₄O₇ differs considerably from the spectrum of another Magnéli oxide, V₃O₅, showing that Raman spectroscopy is an excellent tool for distinguishing between these two phases. Temperature-dependent Raman measurements revealed a significant change of the spectra near the V₄O₇ metal–insulator phase transition. Full article

(This article belongs to the Special Issue Structure and Phase Transformations in Thin Films)

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10 pages, 2714 KiB

Open AccessArticle

Effects of Zr/(Zr+Ti) Molar Ratio on the Phase Structure and Hardness of Ti_xZr_1−xN Films

by Jun Zhang, Lijing Peng, Xiaoyang Wang, Dongling Liu and Nan Wang

Coatings 2021, 11(11), 1342; https://doi.org/10.3390/coatings11111342 - 01 Nov 2021

Cited by 3 | Viewed by 1321

Abstract

Ti_xZr_1−xN hard films with Zr/(Zr+Ti) molar ratios from 20% to 80% were prepared by multi-arc ion plating using any two of elemental Ti, elemental Zr, and TiZr alloy targets. The as-deposited Ti_xZr_1−xN films displayed similar [...] Read more.

Ti_xZr_1−xN hard films with Zr/(Zr+Ti) molar ratios from 20% to 80% were prepared by multi-arc ion plating using any two of elemental Ti, elemental Zr, and TiZr alloy targets. The as-deposited Ti_xZr_1−xN films displayed similar surface and fracture cross-section morphologies and thicknesses. The effects of Zr/(Zr+Ti) molar ratio on the phase composition, preferred growth orientation, and hardness of the films were discussed. The results showed that the as-deposited films had a face-centered cubic structure and exhibited the typical characteristics of substitutional solid solutions. The lattice constant of the films increased monotonically with increasing Zr/(Zr+Ti) molar ratio. Two preferred growth orientations, corresponding to the two hardness peak values, occurred symmetrically at Zr/Ti molar ratios of 40:60 and 60:40. An inflection point with a small reduction in hardness was observed at the Zr/Ti molar ratio of 50:50. Full article

(This article belongs to the Special Issue Structure and Phase Transformations in Thin Films)

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9 pages, 433 KiB

Open AccessArticle

Phase Transition and Magnetoelectric Effect in 2D Ferromagnetic Films on a Ferroelectric Substrate

by Igor Bychkov, Sergey Belim, Ivan Maltsev and Vladimir Shavrov

Coatings 2021, 11(11), 1325; https://doi.org/10.3390/coatings11111325 - 29 Oct 2021

Cited by 4 | Viewed by 1350

Abstract

In this paper, we investigate the behavior of 2D ferromagnetic (FM) films on a ferroelectric (FE) substrate with a periodic structure. The two-dimensional Frenkel–Kontorova (FK) potential simulates the substrate effect on the film. The substrate potential corresponds to a cubic crystal lattice. The [...] Read more.

In this paper, we investigate the behavior of 2D ferromagnetic (FM) films on a ferroelectric (FE) substrate with a periodic structure. The two-dimensional Frenkel–Kontorova (FK) potential simulates the substrate effect on the film. The substrate potential corresponds to a cubic crystal lattice. The Ising model and the Wolf cluster algorithm are used to describe the magnetic behavior of a FM film. The effect of an electric field on a FE substrate leads to its deformation, which is uniform and manifests itself in a period change of the substrate potential. Computer simulation shows that substrate deformations lead to a decrease in the FM film Curie temperature. If the substrate deformations exceed 5%, the film deformations become inhomogeneous. In addition, we derive the dependence of film magnetization on the external electric field. Full article

(This article belongs to the Special Issue Structure and Phase Transformations in Thin Films)

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16 pages, 4406 KiB

Open AccessArticle

The Study of the Influence of Matrix, Size, Rotation Angle, and Magnetic Field on the Isothermal Entropy, and the Néel Phase Transition Temperature of Fe₂O₃ Nanocomposite Thin Films by the Monte-Carlo Simulation Method

by Dung Nguyen Trong, Van Cao Long and Ştefan Ţălu

Coatings 2021, 11(10), 1209; https://doi.org/10.3390/coatings11101209 - 02 Oct 2021

Cited by 13 | Viewed by 2536

Abstract

In this paper, the study of the influence of the matrix structure (mxm) of thin-film, rotation angle (α), magnetic field (B), and size (D) of Fe₂O₃ nanoparticle on the magnetic characteristic quantities such as the magnetization oriented z-direction (M_zE [...] Read more.

In this paper, the study of the influence of the matrix structure (mxm) of thin-film, rotation angle (α), magnetic field (B), and size (D) of Fe₂O₃ nanoparticle on the magnetic characteristic quantities such as the magnetization oriented z-direction (M_zE), z-axis magnetization (M_z), total magnetization (M_tot), and total entropy (S_tot) of Fe₂O₃ nanocomposites by Monte-Carlo (MC) simulation method are studied. The applied MC Metropolis code achieves stability very quickly, so that after 30 Monte Carlo steps (MCs), the change of obtained results is negligible, but for certainty, 84 MCs have been performed. The obtained results show that when the mxm and α increase, the magnetic phase transition appears with a very small increase in temperature Néel (T_Ntot). When B and D increase, T_Ntot increases very strongly. The results also show that in Fe₂O₃ thin films, T_Ntot is always smaller than with Fe₂O₃ nano and Fe₂O₃ bulk. When the nanoparticle size is increased to nearly 12 nm, then T_Ntot = T = 300 K, and between TNtot and D, there is a linear relationship: T_Ntot = −440.6 + 83D. This is a very useful result that can be applied in magnetic devices and in biomedical applications. Full article

(This article belongs to the Special Issue Structure and Phase Transformations in Thin Films)

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13 pages, 4038 KiB

Open AccessArticle

Examination of the Hydrogen Incorporation into Radio Frequency-Sputtered Hydrogenated SiN_x Thin Films

by Nikolett Hegedüs, Riku Lovics, Miklós Serényi, Zsolt Zolnai, Péter Petrik, Judit Mihály, Zsolt Fogarassy, Csaba Balázsi and Katalin Balázsi

Coatings 2021, 11(1), 54; https://doi.org/10.3390/coatings11010054 - 06 Jan 2021

Cited by 8 | Viewed by 2701

Abstract

In this work, amorphous hydrogen-free silicon nitride (a-SiN_x) and amorphous hydrogenated silicon nitride (a-SiN_x:H) films were deposited by radio frequency (RF) sputtering applying various amounts of hydrogen gas. Structural and optical properties were investigated as a function of hydrogen [...] Read more.

In this work, amorphous hydrogen-free silicon nitride (a-SiN_x) and amorphous hydrogenated silicon nitride (a-SiN_x:H) films were deposited by radio frequency (RF) sputtering applying various amounts of hydrogen gas. Structural and optical properties were investigated as a function of hydrogen concentration. The refractive index of 1.96 was characteristic for hydrogen-free SiN_x thin film and with increasing H₂ flow it decreased to 1.89. The hydrogenation during the sputtering process affected the porosity of the thin film compared with hydrogen-free SiN_x. A higher porosity is consistent with a lower refractive index. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of 4 at.% of bounded hydrogen, while elastic recoil detection analysis (ERDA) confirmed that 6 at.% hydrogen was incorporated during the growing mechanism. The molecular form of hydrogen was released at a temperature of ~65 °C from the film after annealing, while the blisters with 100 nm diameter were created on the thin film surface. The low activation energy deduced from the Arrhenius method indicated the diffusion of hydrogen molecules. Full article

(This article belongs to the Special Issue Structure and Phase Transformations in Thin Films)

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15 pages, 2701 KiB

Open AccessArticle

X-ray Diffraction Investigation of Stainless Steel—Nitrogen Thin Films Deposited Using Reactive Sputter Deposition

by Faisal I. Alresheedi and James E. Krzanowski

Coatings 2020, 10(10), 984; https://doi.org/10.3390/coatings10100984 - 15 Oct 2020

Cited by 4 | Viewed by 2425

Abstract

An X-ray diffraction investigation was carried out on nitrogen-containing 304 stainless steel thin films deposited by reactive rf magnetron sputtering over a range of substrate temperature and bias levels. The resulting films contained between ~28 and 32 at.% nitrogen. X-ray analysis was carried [...] Read more.

An X-ray diffraction investigation was carried out on nitrogen-containing 304 stainless steel thin films deposited by reactive rf magnetron sputtering over a range of substrate temperature and bias levels. The resulting films contained between ~28 and 32 at.% nitrogen. X-ray analysis was carried out using both the standard Bragg-Brentano method as well as area-detector diffractometry analysis. The extent of the diffraction anomaly ((002) peak shift) was determined using a calculated parameter, denoted R_B, which is based on the (111) and (002) peak positions. The normal value for R_B for FCC-based structures is 0.75 but increases as the (002) peak is anomalously displaced closer to the (111) peak. In this study, the R_B values for the deposited films were found to increase with substrate bias but decrease with substrate temperature (but still always >0.75). Using area detector diffractometry, we were able to measure d₁₁₁/d₀₀₂ values for similarly oriented grains within the films, and using these values calculate c/a ratios based on a tetragonal-structure model. These results allowed prediction of the (002)/(200) peak split for tetragonal structures. Despite predicting a reasonably accessible split (~0.6°–2.9°–2θ), no peak splitting observed, negating the tetragonal-structure hypothesis. Based on the effects of film bias/temperature on R_B values, a defect-based hypothesis is more viable as an explanation for the diffraction anomaly. Full article

(This article belongs to the Special Issue Structure and Phase Transformations in Thin Films)

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10 pages, 3189 KiB

Open AccessArticle

Determination of the Complex Dielectric Function of Ion-Implanted Amorphous Germanium by Spectroscopic Ellipsometry

by Tivadar Lohner, Edit Szilágyi, Zsolt Zolnai, Attila Németh, Zsolt Fogarassy, Levente Illés, Endre Kótai, Peter Petrik and Miklós Fried

Coatings 2020, 10(5), 480; https://doi.org/10.3390/coatings10050480 - 16 May 2020

Cited by 4 | Viewed by 2699

Abstract

Accurate reference dielectric functions play an important role in the research and development of optical materials. Libraries of such data are required in many applications in which amorphous semiconductors are gaining increasing interest, such as in integrated optics, optoelectronics or photovoltaics. The preparation [...] Read more.

Accurate reference dielectric functions play an important role in the research and development of optical materials. Libraries of such data are required in many applications in which amorphous semiconductors are gaining increasing interest, such as in integrated optics, optoelectronics or photovoltaics. The preparation of materials of high optical quality in a reproducible way is crucial in device fabrication. In this work, amorphous Ge (a-Ge) was created in single-crystalline Ge by ion implantation. It was shown that high optical density is available when implanting low-mass Al ions using a dual-energy approach. The optical properties were measured by multiple angle of incidence spectroscopic ellipsometry identifying the Cody-Lorentz dispersion model as the most suitable, that was capable of describing the dielectric function by a few parameters in the wavelength range from 210 to 1690 nm. The results of the optical measurements were consistent with the high material quality revealed by complementary Rutherford backscattering spectrometry and cross-sectional electron microscopy measurements, including the agreement of the layer thickness within experimental uncertainty. Full article

(This article belongs to the Special Issue Structure and Phase Transformations in Thin Films)

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14 pages, 3612 KiB

Open AccessArticle

Micropillar Compression Study on the Deformation Behavior of Electrodeposited Ni–Mo Films

by Jenő Gubicza, Garima Kapoor, Dávid Ugi, László Péter, János L. Lábár and György Radnóczi

Coatings 2020, 10(3), 205; https://doi.org/10.3390/coatings10030205 - 27 Feb 2020

Cited by 1 | Viewed by 2323

Abstract

The influence of Mo addition on the compression behavior of Ni films was studied by micropillar deformation tests. Thus, films with low (0.4 at.%) and high (5.3 at.%) Mo contents were processed by electrodeposition and tested by micropillar compression up to the plastic [...] Read more.

The influence of Mo addition on the compression behavior of Ni films was studied by micropillar deformation tests. Thus, films with low (0.4 at.%) and high (5.3 at.%) Mo contents were processed by electrodeposition and tested by micropillar compression up to the plastic strain of about 0.26. The microstructures of the films before and after compression were studied by transmission electron microscopy. It was found that the as-deposited sample with high Mo concentration has a much lower grain size (~26 nm) than that for the layer with low Mo content (~240 nm). In addition, the density of lattice defects such as dislocations and twin faults was considerably higher for the specimen containing a larger amount of Mo. These differences resulted in a four-times higher yield strength for the latter sample. The Ni film with low Mo concentration showed a normal strain hardening while the sample having high Mo content exhibited a continuous softening after a short hardening period. The strain softening was attributed to detwinning during deformation. Full article

(This article belongs to the Special Issue Structure and Phase Transformations in Thin Films)

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15 pages, 6537 KiB

Open AccessFeature PaperArticle

Transformations in CrFeCoNiCu High Entropy Alloy Thin Films during In-Situ Annealing in TEM

by Mohamed Arfaoui, György Radnóczi and Viktória Kovács Kis

Coatings 2020, 10(1), 60; https://doi.org/10.3390/coatings10010060 - 09 Jan 2020

Cited by 19 | Viewed by 5258

Abstract

In-situ TEM-heating study of the microstructural evolution of CrFeCoNiCu high entropy alloy (HEA) thin films was carried out and morphological and phase changes were recorded. Post annealing investigation of the samples was carried out by high resolution electron microscopy and EDS measurements. The [...] Read more.

In-situ TEM-heating study of the microstructural evolution of CrFeCoNiCu high entropy alloy (HEA) thin films was carried out and morphological and phase changes were recorded. Post annealing investigation of the samples was carried out by high resolution electron microscopy and EDS measurements. The film is structurally and morphologically stable single phase FCC HEA up to 400 °C. At 450 °C the formation of a BCC phase was observed, however, the morphology of the film remained unchanged. This type of transformation is attributed to diffusionless processes (martensitic or massive). From 550 °C fast morphological and structural changes occur, controlled by volume diffusion processes. Fast growing of a new intermetallic phase is observed which contains mainly Cr and has large unit cell due to chemical ordering of components in <100> direction. The surface of the films gets covered with a CrO-type layer, possibly contributing to corrosion resistance of these. Full article

(This article belongs to the Special Issue Structure and Phase Transformations in Thin Films)

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