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We study microstructure, mechanical, and corrosion properties of Zr1-xCrxBy coatings deposited by hybrid high power impulse/DC magnetron co-sputtering (CrB2-HiPIMS/ZrB2-DCMS). Cr/(Zr + Cr) ratio, x, increases from 0.13 to 0.9, while B/(Zr + Cr) ratio, y, decreases from 2.92 to 1.81. As reference, ZrB2.18 and CrB1.81 layers are grown at 4000 W DCMS. ZrB2.18 and CrB1.81 columns are continual from near substrate toward the surface with open column boundaries. We find that the critical growth parameter to achieve dense films is the ratio of Cr+- dominated ion flux and the (Zr + B) neutral flux from the ZrB2 target. Thus, the alloys are categorized in two groups: films with x < 0.32 (low Cr+/(Zr + B) ratios) that have continuous columnar growth, rough surfaces, and open column boundaries, and films with x >= 0.32 (high Cr+/(Zr + B) ratios) that Cr+-dominated ion fluxes are sufficient to interrupt continuous columns, resulting in smooth surface and dense fine-grain microstructure. The pulsed metal-ion irradiation is more effective in film densification than continuous Ar+ bombardment. Dense Zr0.46Cr0.54B2.40 and Zr0.10Cr0.90B1.81 alloys are hard (> 30 GPa) and almost stress-free with relative nano indentation toughness of 1.3 MPa root m and 2.3 MPa root m, respectively, and remarkedly low corrosion rates (~& nbsp;1.0 x 10(-6) mA/cm(2) for Zr0.46Cr0.54B2.40 and~& nbsp; 2.1 x 10(-6) mA/cm(2) for Zr0.10Cr0.90B1.81). Funding Agencies|Swedish Research Council VR [2018-03957, 2019-00191, 2021-00357]; Swedish Energy Agency [51201-1]; Swedish for Strategic Research (SSF); Swedish National Graduate School in Neutron Scattering (SwedNess); Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials (AFM) at Linkoping University (Faculty Grant SFO Mat LiU)

Hybrid high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) with substrate bias synchronized to the high mass metal-ion fluxes was previously proposed as a solution to reduce energy consumption during physical vapor deposition processing and enable coatings on temperature-sensitive substrates. In this approach, no substrate heating is used (substrate temperature is lower than 150 C-o) and the thermally activated adatom mobility, necessary to grow dense films, is substituted by overlapping collision cascades induced by heavy ion bombardment and consisting predominantly of low-energy recoils. Here, we present direct evidence for the crucial role of W+ ion irradiation in the densification of Ti0.31Al0.60W0.09N films grown by the hybrid W-HiPIMS/TiAl-DCMS co-sputtering. The peak target current density J(max) on the W target is varied from 0.06 to 0.78 A/cm(2) resulting in more than fivefold increase in the number of W+ ions per deposited metal atom, eta = W+/(W + Al + Ti) determined by time-resolved ion mass spectrometry analyses performed at the substrate plane under conditions identical to those during film growth. The DCMS is adjusted appropriately to maintain the W content in the films constant at Ti0.31Al0.60W0.09N. The degree of porosity, assessed qualitatively from cross-sectional SEM images and quantitatively from oxygen concentration profiles as well as nanoindentation hardness, is a strong function of eta ( J m a x ). Layers grown with low eta values are porous and soft, while those deposited under conditions of high eta are dense and hard. Nanoindentation hardness of Ti0.31Al0.60W0.09N films with the highest density is & SIM;33 GPa, which is very similar to values reported for layers deposited at much higher temperatures (420-500 C-o) by conventional metal-ion-based techniques. These results prove that the hybrid HiPIMS/DCMS co-sputtering with bias pulses synchronized to high mass metal ion irradiation can be successfully used to replace conventional solutions. The large energy losses associated with heating of the entire vacuum chamber are avoided, by focusing the energy input to where it is in fact needed, i.e., the workpiece to be coated. Funding Agencies|Swedish Research Council VR [2018-03957]; Swedish Energy Agency [51201-1]; Aforsk Foundation Grant [22-4]; Knut and Alice Wallenberg Foundation [KAW2016.0358, KAW2019.0290]; Carl Tryggers Stiftelse [CTS 20:150]; Competence Center Functional Nanoscale Materials (FunMat-II) VINNOVA Grant [2016-05156]; Swedish Research Council VR-RFI [2017-00646_9]; Swedish Foundation for Strategic Research [RIF14-0053]

Direct-current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS) were used to deposit understoichiometric Ti(1-x)Al(x)B(2-y )diboride coatings by sputtering from a segmented TiB2-AlB2 target using Ar and Kr as sputtering gas. For films with a fixed Al/(Ti + Al) ratio of x = 0.1 (Ti0.9Al0.1B2-y), the B content was varied with y & ISIN; (0.1, 0.6 and 0.7). For films with a fixed y = 0.7 (Ti1-xAlxB1.3), the Al content was varied with x & ISIN; (0.1, 0.4 and 0.7). Evaluation of the mechanical properties of the Ti1-xAlxB1.3 samples showed a reduction in both hardness and elastic modulus with increasing Al concentration, while the Ti0.9Al0.1B2-y samples showed a hardness increase with decreasing B content. Thus, Ti0.9Al0.1B1.3 films exhibited a superior hardness of 46.2 +/- 1.1 GPa and an elastic modulus of 523 & PLUSMN; 7 GPa, compared to the values for Ti0.9Al0.1B1.4 and Ti0.9Al0.1B1.9, showing a hardness of 44 +/- 1 GPa and 36 +/- 1 GPa, and an elastic modulus of 569 +/- 7 GPa and 493 +/- 6 GPa, respectively. The oxidation behavior of the mechanically most promising Ti0.9Al0.1B2-y sample series was investigated through air-annealing at 600 C for durations from 1 h to 10 h. All films formed a mixed non-conformal Al2O3-TiO2 oxide scale which acts as an inward and outward diffusion barrier, significantly reducing the oxidation rate compared to TiBz films, which form an oxide scale consisting of porous TiO2. The thinnest oxide scale after 10 h was found in the B-deficient samples, Ti0.9Al0.1B1.3 and Ti0.9Al0.1B1.4, at ~200 nm, which is significantly below that for Ti0.9Al0.1B1.9 at 320 nm. The enhanced oxidation resistance of highly understoichiometric films is due to the elimination of the B-rich tissue phase that is present at the grain boundaries for higher B content, where the latter has been shown to enhance the rate of oxidation in borides. Funding Agencies|Swedish Foundation for Strategic Research (SSF) [EM16-0004, RIF 14-0074]; Swedish Foundation for Strategic Research (SSF) [EM16-0004]; Knut and Alice Wallenberg (KAW) Foundation for a Fellowship/Scholar Grant [EM16-0004, RIF 14-0074]; KAW; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFOM at-LiU) [RIF 14-0074]; Swedish Research council [EM16-0004]; German Research Foundation (DFG) [RIF 14-0074]; [KAW 2015.0043]; [2009 00971]; [2016-04412]; [SCHN 735/42-1]

In view of the increasing demand for achieving sustainable development, the quest for lowering energy consumption during thin film growth by magnetron sputtering becomes of particular importance. In addition, there is a demand for low-temperature growth of dense, hard coatings for protecting temperature-sensitive substrates. Here, we explore a method, in which thermally-driven adatom mobility, necessary to obtain high-quality fully-dense films, is replaced with that supplied by effective low-energy recoil creation resulting from high-mass metal ion irradiation of the growing film surface. This approach allows the growth of dense and hard films with no external heating at substrate temperatures T-s not exceeding 130 degrees C in a hybrid high-power impulse and de magnetron co-sputtering (HiPIMS/DCMS) setup involving a high mass (m > 180 amu) HiPIMS target and metal- ion-synchronized bias pulses. We specifically investigate the effect of the metal ion mass on the extent of densification, phase content, nanostructure, and mechanical properties of metastable cubic Ti0.50Al0.50N based thin films, which present outstanding challenges for phase stability control. Ti0.50Al0.50N based thin films are irradiated by group VIB transition metal (TM) target ions generated by Me-HiPIMS discharge, in which Me = Cr (m(Cr)= 52.0 amu), Mo (m(Mo) = 96.0 amu), and W (m(W) = 183.8 amu). Three series of (Ti1-yAly)(1-x)MexN films are grown with x = Me/(Me+Al+Ti) varied intentionally by adjusting the DCMS powers, while y = Al/(Al+Ti) also varies as a result of Me+ ion irradiation. Results reveal a strong dependence of film properties on the mass of the HiPIMS-generated metal ions. All layers deposited with Cr+ irradiation exhibit porous nanostructure, high ox- ygen content, and poor mechanical properties. In contrast, (Ti1-yAly)(1-x)WxN films are fully-dense even with the lowest W concentration, x = 0.09, show no evidence of hexagonal AlN precipitation, and exhibit state-of the-art mechanical properties typical of Ti0.50Al0.50N grown at 500 degrees C. The process energy consumption is lowered by 64% with no negative impact on the coating quality. TRIM simulations provide an insight into the densification mechanisms. Funding Agencies|Swedish Energy AgencySwedish Energy Agency [51201-1]; Knut and Alice Wallenberg Foundation Scholar Grant [KAW2016.0358]; Competence Center Functional Nanoscale Materials (FunMat-II) VINNOVA grantVinnova [201605156]; Swedish Research Council VR Grant [2018-03957]; VINNOVA grantVinnova [2019-04882]; Carl Tryggers Stiftelse for Vetenskaplig Forskning [CTS 17:166, CTS 15:219, CTS 14:431]; Swedish Research Council VR-RFISwedish Research Council [2017-00646_9]; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [RIF14-0053]

Transition-metal diboride thin films, which have high melting points, excellent hardness, and good chemical and thermal conductivity, severely suffer from rapid oxidation in air. Here, we explore the influence of varying B content and resulting nanostructure change on the oxidation properties of TiBx thin films, with x = 1.43, 2.20, and 2.70. Results show that all as-deposited layers have columnar structure. The column boundaries of asdeposited TiB2.20 and TiB2.20 films grown by direct current magnetron sputtering (DCMS) are B-rich, while the as-deposited TiB1.43 films grown by high-power impulse magnetron sputtering (HiPIMS) show no apparent grain boundary phases and contain Ti-rich planar defects. The oxidation rate of TiBL43 air-annealed at 400 degrees C up to 48 h is significantly lower than that of TiB2.20 and TiB2.20 films. The oxidation rate of TiB1.43, TiB2.20, and TiB2.20 films was measured at 2.9 +/- 1.5, 7.1 +/- 1.0, and 20.0 +/- 5.0 nm/h, respectively, with no spallation of even as thick oxide scales as 0.5 mu m in any of the films. The improved oxidation resistance can be explained by the absence of B-rich tissue phase at the column boundaries of understoichiometric TiBx films, a phase that interlaces the nanocolumnar TiB2 structures in the corresponding overstoichiometric films. An easy oxidation pathway is thus eliminated. Funding Agencies|Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research [EM16-0004]; Knut and Alice Wallenberg Foundation (KAW)Knut & Alice Wallenberg Foundation [KAW 2015.0043, RIF 14-0074]; KAW; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat-LiU) [2009 00971]; Swedish Research CouncilSwedish Research CouncilEuropean Commission [642-2013-8020, 2016-04412]

Hybrid high power impulse/direct current magnetron sputtering (HiPIMS/DCMS) film growth technique with metal-ion-synchronized substrate bias allows for significant energy savings as compared to conventional PVD methods. For carefully selected type of metal ion irradiation, taking into account ion mass, ionization potential, and reactivity towards working gas, fully dense and hard films can be obtained with no intentional substrate heating. The thermally-driven adatom mobility, which is an essential densification mechanism in conventional film growth that takes place at elevated temperatures, is replaced with that supplied by effective low-energy recoil creation. In this contribution we explore effects of the high-mass W+ irradiation, which has proven to be the most efficient in densifying Ti0.50Al0.50N layers, serving here as a model system, grown with no substrate heating. We study the effects of two essential parameters: W+ energy EW+ and W concentration x, on film porosity, phase content, nanostructure, and mechanical properties. EW+ varies from similar to 90 to similar to 630 eV (controlled by substrate bias voltage amplitude V-s) and x from 0.02 to 0.12 (controlled by the HiPIMS pulse length), while the HiPIMS peak target current is kept constant. Results reveal that a strong coupling exists between the W+ incident energy and the minimum W concentration required to grow dense layers. Funding Agencies|Swedish Research Council VRSwedish Research Council [2018-03957]; Swedish Energy AgencySwedish Energy Agency [51201-1]; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [KAW2016.0358]; Competence Center Functional Nanoscale Materials (FunMat-II) VINNOVA grantVinnova [2016-05156]; Carl Tryggers Stiftelse for Vetenskaplig Forskning [CTS 20:150, CTS 15:219, CTS 14:431]; Swedish research council VR-RFISwedish Research Council [2017-00646_9]; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [RIF14-0053]

TiBx thin films with a B content of 1.43 ≤ x ≤ 2.70 were synthesized using high-power impulse magnetron sputtering (HiPIMS) and direct-current magnetron sputtering (DCMS). HiPIMS allows compositions ranging from understoichiometric to overstoichiometric dense TiBx thin films with a B/Ti ratio between 1.43 and 2.06, while DCMS yields overstoichiometric TiBx films with a B/Ti ratio ranging from 2.20 to 2.70. Excess B in overstoichiometric TiBx thin films from DCMS results in a hardness up to 37.7 ± 0.8 GPa, attributed to the formation of an amorphous B-rich tissue phase interlacing stoichiometric TiB2 columnar structures. We furthermore show that understoichiometric TiB1.43 thin films synthesized by HiPIMS, where the deficiency of B is found to be accommodated by Ti-rich planar defects, exhibit a superior hardness of 43.9 ± 0.9 GPa. The apparent fracture toughness and thermal conductivity of understoichiometric TiB1.43 HiPIMS films are 4.2 ± 0.1 MPa√m and 2.46 ± 0.22 W/(m·K), respectively, as compared to corresponding values for overstoichiometric TiB2.70 DCMS film samples of 3.1 ± 0.1 MPa√m and 4.52 ± 0.45 W/(m·K). This work increases the fundamental understanding of understoichiometric TiBx thin films and their materials properties, and shows that understoichiometric films have properties matching or going beyond those with excess B. Fulltext published under Creative Commons license CC BY 4.0https://creativecommons.org/licenses/by/4.0/Funding agencies: Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research [EM16-0004]; Research Infrastructure Fellow program from the Knut and Alice Wallenberg (KAW) Foundation [RIF 14-0074]; KAW; Swedish Government Strategic Research Area

Nanometer-sized structures, surfaces and sub-surface phenomena have played an enormous role in science and technological applications and represent a driving-force of current interdisciplinary science. Recent developments include the atomic-scale characterization of nanoparticles, molecular reactions at surfaces, magnetism at the atomic scale, photoelectric characterization of nanostructures as well as two-dimensional solids. Research and development of smart nanostructured materials governed by their surface properties is a rapidly growing field. The main challenge is to develop an accurate and robust electronic structure description. The density of surface-related trap states is analyzed by transient UV photoconductivity and temperature-dependent admittance spectroscopy. An advanced application of thin films on shaped substrates is the deposition of catalytic layers on hollow glass microspheres for hydrogen storage controlled exothermal hydrolytic release. Surface properties of thin films including dissolution and corrosion, fouling resistance, and hydrophilicity/hydrophobicity are explored to improve materials response in biological environments and medicine. Trends in surface biofunctionalization routes based on vacuum techniques, together with advances in surface analysis of biomaterials, are discussed. Pioneering advances in the application of X-ray nanodiffraction of thin film cross-sections for characterizing nanostructure and local strain including in-situ experiments during nanoindentation are described. Precise measurements and control of plasma properties are important for fundamental investigations and the development of next generation plasma-based technologies. Critical control parameters are the flux and energy distribution of incident ions at reactive surfaces; it is also crucial to control the dynamics of electrons initiating non-equilibrium chemical reactions. The most promising approach involves the exploitation of complementary advantages in direct measurements combined with specifically designed numerical simulations. Exciting new developments in vacuum science and technology have focused on forward-looking and next generation standards and sensors that take advantage of photonics based measurements. These measurements are inherently fast, frequency based, easily transferrable to sensors based on photonics and hold promise of being disruptive and transformative. Realization of Pascal, the SI unit for pressure, a cold-atom trap based ultra-high and extreme high vacuum (UHV and XHV) standard, dynamic pressure measurements and a photonic based thermometer are three key examples that are presented.

Boron-containing materials exhibit a unique combination of ceramic and metallic properties that are sensitively dependent on their given chemical bonding and elemental compositions. However, determining the composition, let alone bonding, with sufficient accuracy is cumbersome with respect to boron, being a light element that bonds in various coordinations. Here, we report on the comprehensive compositional analysis of transition-metal diboride (TMBx) thin films (TM = Ti, Zr, and Hf) by energy-dispersive x-ray spectroscopy (EDX), x-ray photoelectron spectroscopy (XPS), time-of-flight elastic recoil detection analysis (ToF-ERDA), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA). The films are grown on Si and C substrates by dc magnetron sputtering from stoichiometric TMB2 targets and have hexagonal AlB2-type columnar structures. EDX considerably overestimates B/TM ratios, x, compared to the other techniques, particularly for ZrBx. The B concentrations obtained by XPS strongly depend on the energy of Ar+ ions used for removing surface oxides and contaminants prior to analyses and are more reliable for 0.5 keV Ar+. ToF-ERDA, RBS, and NRA yield consistent compositions in TiBx. They also prove TiBx and ZrBx films to be homogeneous with comparable B/TM ratios for each film. However, ToF-ERDA, employing a 36-MeV 127I8+ beam, exhibits challenges in depth resolution and quantification of HfBx due to plural and multiple scattering and associated energy loss straggling effects. Compared to ToF-ERDA, RBS (for the film grown on C substrates) and NRA provide more reliable B/Hf ratios. Overall, a combination of methods is recommended for accurately pinpointing the compositions of borides that contain heavy transition metals. Funding agencies: The SwedishResearch Council VR (Grant Nos. 2021-00357, 2018-03957, and642-2013-8020); the Knut and Alice Wallenberg (KAW) Foundation for project funding (No. KAW 2015.0043), the Swedish Energy Agency under Project No. 51201-1, Carl Tryggers Stiftelse (Contract Nos. CTS 15:219, CTS 20:150, and CTS 14:431); the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO Mat LiU No. 2009 00971), the Swedish Research Council VRRFI (No. 2017-00646_9) for supporting the Accelerator based ion technology center; the Swedish Foundation for StrategicResearch (Contract No. RIF14-0053)

High-power impulse magnetron sputtering (HiPIMS) of materials systems with metal/gas-atom mass ratios m(Me)/m(g) near, or less than, unity presents a challenge for precise timing of synchronous substrate-bias pulses to select metal-ion irradiation of the film and, thus, reduce stress while increasing layer density during low-temperature growth. The problem stems from high gas-ion fluxes Fg+(t) at the substrate, which overlap with metal-ion fluxes FMe+(t). We use energy-and time-dependent mass spectrometry to analyze FMe+(t) and Fg+(t) for Group IVb transition-metal targets in Ar and show that the time-and energy-integrated metal/gas ion ratio NMe+/NAr+ at the substrate can be controlled over a wide range by adjusting the HiPIMS pulse length tau(ON), while maintaining the peak target current density J(T,peak) constant. The effect is a consequence of severe gas rarefaction which scales with J(T)(t). For Ti-HiPIMS, terminating the discharge at the maximum J(T)(t), corresponding to tau(ON) = 30 mu s, there is an essentially complete loss of Ar+ ion intensity, yielding NTi+/NAr+ similar to 60. With increasing tau(ON),J(T)(t) decreases and NTi+/NAr+ gradually decays, due to Ar refill, to similar to 1 with tau(ON) = 120 s. Time-resolved ion-energy distribution functions confirm that the degree of rarefaction depends on tau(ON): for shorter pulses, tau ONHTC/SUBTAG amp;lt; FORTITLEHTC_RETAIN 60 [rs, the original sputtered-atom Sigmund-Thompson energy distributions are preserved long after the HiPIMS pulse, which is in distinct contrast to longer pulses, tau(ON) amp;gt;= 60 mu s, for which the energy distributions collapse into narrow ther-malized peaks. Thus, optimizing the HiPIMS pulse width minimizes the gas-ion flux to the substrate independent of m(Me)/m(g). Funding Agencies|Swedish Research Council VR [2014-5790]; Aforsk Foundation [16-359]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]; Knut and Alice Wallenberg Foundation Fellowship [KAW 2015.0043]; Carl Tryggers Stiftelse for Vetenskaplig Forskning [CTS 15:219, CTS 14:431]

We recently showed that Zr1−xTaxBy thin films have columnar nanostructure in which column boundaries are B-rich for x < 0.2, while Ta-rich for x ≥ 0.2. Layers with x ≥ 0.2 exhibit higher hardness and, simultaneously, enhanced toughness. Here, we determine the atomic-scale nanostructure of sputter-deposited columnar Zr0.7Ta0.3B1.5 thin films. The columns, 95 ± 17 Å, are core/shell nanostructures in which 80 ± 15-Å cores are crystalline hexagonal-AlB2-structure Zr-rich stoichiometric Zr1−xTaxB2. The shell structure is a narrow dense, disordered region that is Ta-rich and highly B-deficient. The cores are formed under intense ion mixing via preferential Ta segregation, due to the lower formation enthalpy of TaB2 than ZrB2, in response to the chemical driving force to form a stoichiometric compound. The films with unique combination of nanosized crystalline cores and dense metallic-glass-like shells provide excellent mechanical properties. Funding agencies: Knut and Alice Wallenberg (KAW) FoundationKnut & Alice Wallenberg Foundation [KAW 2015.0043]; electron microscopy laboratory in Linkoping; Swedish Research Council VRSwedish Research Council [2014-5790, 2018-03957, 2019-05403, 642-2013-8020]; VINNOVA Gran

We report on a comprehensive analysis of titanium boride thin films by x-ray photoelectron spectroscopy (XPS). Films were grown by both direct current magnetron sputtering and high-power impulse magnetron sputtering from a compound TiB2 target in Ar discharge. By varying the deposition parameters, the film composition could be tuned over the wide range 1.3 ≲ B / Ti ≲ 3.0, as determined by elastic recoil detection analysis and Rutherford backscattering spectrometry. By comparing spectra over this wide range of compositions, we can draw original conclusions about how to interpret XPS spectra of TiBx. By careful spectra deconvolution, the signals from Ti–Ti and B–B bonds can be resolved from those corresponding to stoichiometric TiB2. The intensities of the off-stoichiometric signals can be directly related to the B/Ti ratio of the films. Furthermore, we demonstrate a way to obtain consistent and quantum-mechanically accurate peak deconvolution of the whole Ti 2p envelope, including the plasmons, for both oxidized and sputter-cleaned samples. Due to preferential sputtering of Ti over B, the film B/Ti ratio is best determined without sputter etching of the sample surface. This allows accurate compositional determination, assuming that extensive levels of oxygen are not present in the sample. Fully dense films can be accurately quantified for at least a year after deposition, while underdense samples do not give reliable data if the O/Ti ratio on the unsputtered surface is ≳ 3.5. Titanium suboxides detected after sputter etching is further indicative of oxygen penetrating the sample, and quantification by XPS should not be trusted.

Rocksalt-structure (B1) (V,Mo)N alloys are inherently hard and tough ceramics. However, the mechanical properties and thermal stability of (V,Mo)N solid solutions at temperatures ⪆ 700 °C of relevance for practical applications have not been previously investigated. In this work, we synthesize single-phase B1 polycrystalline V0.57Mo0.43N0.95 coatings to investigate the effects induced by temperature on the nanostructural evolution and hardness (H) of the material. Nanoindentation measurements show that the as-deposited film (H = 23 ± 3 GPa) becomes ≈30% harder (up to 31 ± 2 GPa) upon annealing at 730 °C. Experimental characterization and analyses, based on dispersive X-ray spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM), reveal that the age-hardening effect originates from decomposition of the solid solution into coherent strained cubic VN-rich/MoN-rich domains. The experimental results are complemented by the composition/temperature (V,Mo)N phase diagram – constructed upon ab initio molecular dynamics free-energies – which indicates that the separation observed in the solid solutions is of spinodal nature. Films annealed at temperatures exceeding 850 °C undergo structural coarsening, with formation of hexagonal MoxNy and cubic VN phases, which cause a decrease in hardness to ≈22 GPa. Our present findings indicate that (V,Mo)N coatings may offer outstanding mechanical performances during operation at elevated temperatures.

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Over the past decades, enormous effort has been dedicated to enhancing the hardness of refractory ceramic materials. Typically, however, an increase in hardness is accompanied by an increase in brittleness, which can result in intergranular decohesion when materials are exposed to high stresses. In order to avoid brittle failure, in addition to providing high strength, films should also be ductile, i.e., tough. However, fundamental progress in obtaining hard-yet-ductile ceramics has been slow since most toughening approaches are based on empirical trial-and-error methods focusing on increasing the strength and ductility extrinsically, with a limited focus on understanding thin-film toughness as an inherent physical property of the material. Thus, electronic structure investigations focusing on the origins of ductility vs. brittleness are essential in understanding the physics behind obtaining both high strength and high plastic strain in ceramics films. Here, we review recent progress in experimental validation of density functional theory predictions on toughness enhancement in hard ceramic films, by increasing the valence electron concentration, using examples from the V1-xWxN and V1-xMoxN alloy systems. Funding Agencies|Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [KAW 2011-0094]; Swedish Research CouncilSwedish Research Council [VR 2014-5790]; Swedish Government Strategic Research Area Grant in Materials Science (SFO Mat-LiU) on Advanced Functional Materials; Olle Engkvist Foundation; VINN Excellence Center Functional Nanoscale Materials (FunMat-2) Grant [2016-05156]

Refractory transition-metal diborides exhibit inherent hardness. However, this is not always sufficient to prevent failure in applications involving high mechanical and thermal stress, since hardness is typically accompanied by brittleness leading to crack formation and propagation. Toughness, the combination of hardness and ductility, is required to avoid brittle fracture. Here, the authors demonstrate a strategy for simultaneously enhancing both hardness and ductility of ZrB2-rich thin films grown in pure Ar on Al2O3(0001) and Si(001) substrates at 475 °C. ZrB2.4 layers are deposited by dc magnetron sputtering (DCMS) from a ZrB2 target, while Zr1−xTaxBy alloy films are grown, thus varying the B/metal ratio as a function of x, by adding pulsed high-power impulse magnetron sputtering (HiPIMS) from a Ta target to deposit Zr1−xTaxBy alloy films using hybrid Ta-HiPIMS/ZrB2-DCMS sputtering with a substrate bias synchronized to the metal-rich portion of each HiPIMS pulse. The average power P Ta (and pulse frequency) applied to the HiPIMS Ta target is varied from 0 to 1800 W (0 to 300 Hz) in increments of 600 W (100 Hz). The resulting boron-to-metal ratio, y = B/(Zr+Ta), in as-deposited Zr1−xTaxBy films decreases from 2.4 to 1.5 as P Ta is increased from 0 to 1800 W, while x increases from 0 to 0.3. A combination of x-ray diffraction (XRD), glancing-angle XRD, transmission electron microscopy (TEM), analytical Z-contrast scanning TEM, electron energy-loss spectroscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and atom-probe tomography reveals that all films have the hexagonal AlB2 crystal structure with a columnar nanostructure, in which the column boundaries of layers with 0 ≤ x

It has been shown both experimentally and by density functional theory calculations that the primary diffusing species during the epitaxial growth of TiN/TiN(001) are Ti and N adatoms together with ...

Reactive transition-metal (TM) nitride film growth employing bias-synchronized high power impulse magnetron sputtering (HiPIMS) requires a detailed knowledge of the time evolution of metal-and gas-ion fluxes incident at the substrate plane in order to precisely tune momentum transfer and, hence, provide the recoil density and energy necessary to eliminate film porosity at low deposition temperatures without introducing significant film stress. Here, the authors use energy- and time-dependent mass spectrometry to analyze the evolution of metal-and gas-ion fluxes at the substrate plane during reactive HiPIMS sputtering of groups IVb and VIb TM targets in Ar/N-2 atmospheres. The time-and energy-integrated metal/gas ion ratio NMe+/Ng+ incident at the substrate is significantly lower for group IVb TMs (ranging from 0.2 for Ti to 0.9 for Hf), due to high N-2 reactivity which results in severely reduced target sputtering rates and, hence, decreased rarefaction. In contrast, for less reactive group VIb metals, sputtering rates are similar to those in pure Ar as a result of significant gas heating and high NMe+/Ng+ ratios, ranging from 2.3 for Cr to 98.1 for W. In both sets of experiments, the peak target current density is maintained constant at 1 A/cm(2). Within each TM group, NMe+/N(g+)scales with increasing metal-ion mass. For the group-VIb elements, sputtered-atom Sigmund-Thompson energy distributions are preserved long after the HiPIMS pulse, in contradistinction to group-IVb TMs for which the energy distributions collapse into narrow thermalized peaks. For all TMs, the N+ flux dominates that of N-2(+) ions, as the molecular ions are collisionally dissociated at the target, and N+ exhibits ion energy distribution functions resembling those of metal ions. The latter result implies that both N+ and Me+ species originate from the target. High-energy Ar+ tails, assigned to ionized reflected-Ar neutrals, are observed with heavier TM targets. Published by the AVS. Funding Agencies|Swedish Research Council VR Grant [2014-5790]; Aforsk foundation [16359]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; Knut and Alice Wallenberg foundation [KAW 2015.0043]

TiBx thin films grown from compound TiB2 targets by magnetron sputter deposition are typically highly over-stoichiometric, with x ranging from 3.5 to 2.4, due to differences in Ti and B preferential-ejection angles and gas-phase scattering during transport from the target to the substrate. Here, the authors demonstrate that stoichiometric TiB2 films can be obtained using highpower impulse magnetron sputtering (HiPIMS) operated in power-controlled mode. The B/Ti ratio x of films sputter-deposited in Ar is controllably varied from 2.08 to 1.83 by adjusting the length of HiPIMS pulses t(on) between 100 and 30 mu s, while maintaining average power and pulse frequency constant. This results in peak current densities J(T), peak ranging from 0.27 to 0.88 A/cm(2). Energy- and time-resolved mass spectrometry analyses of the ion fluxes incident at the substrate position show that the density of metal ions increases with decreasing t(on) due to a dramatic increase in J(T, peak) resulting in the strong gas rarefaction. With t(on)amp;lt;60 mu s (J(T),(peak)amp;gt; 0.4 A/cm(2)), film growth is increasingly controlled by ions incident at the substrate, rather than neutrals, as a result of the higher plasma dencity and, hence, electron-impact ionization probablity. Thus, since sputter- ejected Ti atoms have a higher probability of being ionized than B atoms, due to their lower first-ionization potential and larger ionization cross-section, the Ti concentration in as-deposited films increases with decreasing ton (increasing J(T,peak)) as ionized sputtered species are steered to the substrate by the plasma in order to maintain charge neutrality. Published by the AVS. Funding Agencies|Swedish Research Council VR [2014-5790, 642-2013-8020]; Knut and Alice Wallenberg foundation [KAW 2015.0043]; Aforsk foundation [16-359]; Carl Tryggers Stiftelse Contract [CTS 15:219, CTS 17:166, CTS 14:431]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]

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Adding Si into transition-metal nitride hard coatings is known to enhance mechanical properties and oxidation resistance. At the same time, however, Si promotes precipitation of wurtzite-structure AlN in Ti1-xAlxN during deposition by magnetron sputtering or cathodic-arc-evaporation, resulting in a decrease in layer hardness. Here, we report nanocomposite films of metastable cubic NaCl-structure TiAlSiN deposited using a hybrid approach combining high-power impulse magnetron sputtering (HiPIMS) from an Al target with DC magnetron sputtering (DCMS) from TiSi targets (Al-HiPIMS/TiSi-DCMS) in which a substrate bias is synchronized to the metal-rich portion of each HiPIMS pulse. The Al/(Al + Ti) ratio is varied from 0.26 to 0.77 by adjusting the TiSi target power, while the Si content ranges from 7.6 to 10.3 at.%. Cubic-structure TiAlSiN solid solutions are obtained with a maximum Al/(Al + Ti) atomic ratio of 0.59 and 9.4 at.% Si. Excess Si segregates to grain boundaries to form a SiNx-rich tissue phase. The hardness H and elastic modulus E of cubic TiAlSiN films increase from H = 19.4 ± 1.7 and E = 322 ± 12 for TiAlSiN layer with Al/(Al + Ti) = 0.26 to H = 37.3 ± 1.3 and E = 388 ± 12 GPa for TiAlSiN layer with Al/(Al + Ti) = 0.59. The TiAlSiN films also exhibit a low intrinsic stress (−0.55 to 0.62 GPa), resulting in a combination of properties: superior hardness and low stress.

W+ irradiation of TiAlN is used to demonstrate growth of dense, hard, and stress-free refractory nitride coatings with no external heating during reactive magnetron sputtering. Ti0.40Al0.27W0.33N nanocomposite films are deposited on Si(001) substrates using hybrid high-power impulse and dc magnetron cosputtering (HiPIMS and DCMS) in an industrial sputtering system employing substrate rotation during film growth from six cathodes. Two W targets powered by HiPIMS serve as a pulsed source of energetic W+ ions with incident fluxes analyzed by in situ time- and energy-resolved mass spectroscopy, while the remaining four targets (two elemental Ti targets and two Ti plates with Al plugs) are operated in the DCMS mode (W-HiPIMS/TiAl-DCMS) to provide a continuous flux of metal atoms and sustain a high deposition rate. A negative substrate bias V-s is applied only in synchronous with the W+-ion-rich portion of each HiPIMS pulse in order to provide film densification by heavy-ion irradiation of the TiAlN layers deposited between W+-ion exposures. W is selected for densification due to its high mass and relatively low reactivity with N-2, thus minimizing target poisoning while enhancing gas rarefaction. Dense Ti0.40Al0.27W0.33N alloy films, grown with no external substrate heating (substrate temperature T-s lower than 150 degrees C due to heat load from the plasma) and V-s=500V, exhibit a nanoindentation hardness of H=23.1GPa and an elastic modulus of E=378GPa, which are, respectively, 210% and 40% higher than for reference underdense DCMS Ti0.58Al0.42N films grown under the same conditions, but without W+ irradiation. The W ion bombardment does not affect the film stress state, which is compressive and low at 1.2GPa. Funding Agencies|Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [KAW2016.0358]; VINN Excellence Center Functional Nanoscale Materials (FunMat-2) [2016-05156]; Swedish Research Council VRSwedish Research Council [2018-03957]; VINNOVAVinnova [2018-04290]; Aforsk Foundation [16-359]; Carl Tryggers Stiftelse [CTS 17:166]; National Natural Science Foundation of China (NNSFC)National Natural Science Foundation of China [51901048, 51875109]; Natural Science Foundation of Guangdong ProvinceNational Natural Science Foundation of Guangdong Province [2018A030310546, 2019A1515012234]

Metastable Ti1-xAlxN (0

2.5 μm thick TiAlCN/VCN coatings were deposited by a reactive high power impulse magnetron sputtering (HIPIMS) process. Cross-sectional TEM showed gradual evolution of the structure of the coating with thickness. The initial structure is a nanoscale multilayer with sharp interlayer interfaces. This transforms to nanocomposite of TiAlCN and VCN nanocrystalline grains surrounded by a C-rich tissue phase and finally changes to an amorphous carbon rich Me-C phase. In contrast deposition in similar conditions using standard magnetron sputtering produces a well-defined nanoscale multilayer structure. Depth profiling by AES showed that the carbon content in the HIPIMS coating gradually increased from 25% at the coating substrate interface to 70% at the top thus supporting the TEM observations. Energy-resolved mass spectrometry revealed that HIPIMS plasma is a factor of 10 richer in C1 + ions, and therefore more reactive, as compared to the plasma generated by standard magnetron discharge at the same conditions. The peculiar structure evolution in HIPIMS is discussed in relation to target poisoning effect and carbon outward diffusion during coating growth. Highly abrasive AlSi9Cu1 alloy was dry machined using TiAlCN/VCN coated 25 mm diameter end mills to investigate the coating-work piece material interaction. Green (532 nm excitation) and ultraviolet (325 nm excitation) Raman spectroscopy was employed to identify the phase composition of the built up material on the cutting edge and chip (swarf) surfaces produced during machining. These analyses revealed formation of lubricious Magneli phases namely V2O5 and graphitic carbon as well as highly abrasive SiO2 and mixed (AlSi)O thus shedding light on the wear processes and coating tribological behavior during machining.

Ab initio and classical molecular dynamics (AIMD and CMD) simulations reveal that Ti adatoms on TiN(001) surfaces migrate between neighboring fourfold hollow sites primarily along in-plane less than100greater than channels. less than100greater than and less than110greater than single jumps, as well as less than100greater than double jump rates, obtained directly from MD runs as a function of temperature, are used to determine diffusion activation energies Ea, and attempt frequencies A, for the three preferred Ti adatom migration pathways on TiN(001). From transition rates Aexp[-Ea / (k(B)T)], we determine adatom surface distribution probabilities as a function of time, which are used to calculate adatom diffusion coefficients D(T). AIMD and CMD predictions are consistent and complementary. Using CMD, we investigate the effect on the adatom jump rate of varying the phonon wavelength degrees of freedom by progressively increasing the supercell size. We find that long-wavelength phonons significantly contribute to increasing adatom mobilities at temperatures less than= 600 K, but not at higher temperatures. Finally, by directly tracking the Ti adatom mean-square displacement during CMD runs, we find that Ti adatom jumps are highly correlated on TiN(001), an effect that yields lower D-s values (D-s(corr)) than those estimated from uncorrelated transition probabilities. The temperature-dependent diffusion coefficient is D-s(corr) (T) = (4.5 x 10(-4) Cm-2 s(-1)) exp[-0.55 eV / (k(B)T)].

A hybrid deposition process consisting of reactive high-power pulsed and dc magnetron cosputtering (HIPIMS and DCMS) from Ti and Al targets is used to grow Ti 1− x Al x N alloys, with x ~ 0.6, on Si(001) at 500 °C. Two series of films are deposited in which the energy and momentum of metal ions incident at the growing film are individually varied. In both sets of experiments, a negative bias V s ranging from 20 to 280 V is applied to the substrate in synchronous, as determined by in-situ mass spectrometry, with the metal-ion-rich part of the HIPIMS pulse. Ion momentum is varied by switching the HIPIMS and dc power supplies to change the mass m and average charge of the primary metal ion. Al-HIPIMS/Ti-DCMS layers grown under Al + ( m Al = 26.98 amu) bombardment with 20 ≤ V s ≤ 160 V are single-phase NaCl-structure alloys, while films deposited with V s > 160 V are two-phase, cubic plus wurtzite. The corresponding critical average metal-ion momentum transfer per deposited atom for phase separation is 〈 p d ⁎ 〉 ≥ 135 [eV-amu] 1/2 . In distinct contrast, layers deposited in the Ti-HIPIMS/Al-DCMS configuration with Ti + /Ti 2+ ( m Ti = 47.88 amu) ion irradiation are two-phase even with the lowest bias, V s = 20 V, for which 〈 p d ⁎ 〉 > 135 [eV-amu] 1/2 . Precipitation of wurtzite-structure AlN is primarily determined by the average metal-ion momentum transfer to the growing film, rather than by the deposited metal-ion energy. Ti-HIPIMS/Al-DCMS layers grown with V s = 20 V are two-phase with compressive stress σ = − 2 GPa which increases to − 6.2 GPa at V s = 120 V; hardness H values range from 17.5 to 27 GPa and are directly correlated with σ . However, for Al-HIPIMS/Ti-DCMS, the relatively low mass and single charge of the Al + ion permits tuning properties of metastable cubic Ti 0.38 Al 0.62 N by adjusting V s to vary, for example, the hardness from 12 to 31 GPa while maintaining σ ~ 0.

Improved toughness is a central goal in the development of wear-resistant refractory ceramic coatings. Extensive theoretical and experimental research has revealed that NaCl-structure VMoN alloys exhibit surprisingly high ductility combined with high hardness and toughness. However, during operation, protective coatings inevitably oxidize, a problem that may compromise material properties and performance. Here, the authors explore the role of oxidation in altering VMoN properties. Density functional theory and theoretical intrinsic hardness models are used to investigate the mechanical behavior of cubic V0.5Mo0.5N1-xOx solid solutions as a function of the oxygen concentration x. Elastic constant and intrinsic hardness calculations show that oxidation does not degrade the mechanical properties of V0.5Mo0.5N. Electronic structure analyses indicate that the presence of oxygen reduces the covalent bond character, which slightly lowers the alloy strength and intrinsic hardness. Nevertheless, the character of metallic d-d states, which are crucial for allowing plastic deformation and enhancing toughness, remains unaffected. Overall, the authors results suggest that VMoNO oxynitrides, with oxygen concentrations as high as 50%, possess high intrinsic hardness, while still being ductile. Published by the AVS. Funding Agencies|Swedish Government Strategic Research Area Grant in Materials Science on Advanced Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]; Olle Engkvist Foundation; competence center FunMat-II - Swedish Agency for Innovation Systems (Vinnova)Vinnova [2016-05156]

Ion irradiation is a key tool for controlling the nanostructure, phase content, and physical properties of refractory ceramic thin films grown at low temperatures by magnetron sputtering. However, in contrast to gas-ion bombardment, the effects of metal-ion irradiation on properties of refractory ceramic thin films have not been extensively studied due to (i) low metal-ion concentrations (a few percents) during standard direct-current magnetron sputtering (DCMS) and (ii) difficulties in separating metal-ion from gas-ion fluxes. Recently, the situation has changed dramatically, thanks to the development of high-power impulse magnetron sputtering (HiPIMS), which provides highly-ionized metal-ion plasmas. In addition, careful choice of sputtering conditions allows exploitation of gas-rarefaction effects such that the charge state, energy, and momentum of metal ions incident at the growing film surface can be tuned. This is possible via the use of pulsed substrate bias, synchronized to the metal-ion-rich portion of each HiPIMS pulse. In this review, the authors begin by summarizing the results of time-resolved mass spectrometry analyses performed at the substrate position during HiPIMS and HiPIMS/DCMS cosputtering of transition-metal (TM) targets in Ar and Ar/N2 atmospheres. Knowledge of the temporal evolution of metal- and gas-ion fluxes is essential for precise control of the incident metal-ion energy and for minimizing the role of gas-ion irradiation. Next, the authors review results on the growth of binary, pseudobinary, and pseudoternary TM nitride alloys by metal-ion-synchronized HiPIMS. In contrast to gas ions, a fraction of which are trapped at interstitial sites, metal ions are primarily incorporated at lattice sites resulting in much lower compressive stresses. In addition, the closer mass match with the film-forming species results in more efficient momentum transfer and provides the recoil density and energy necessary to eliminate film porosity at low deposition temperatures. Several novel film-growth pathways have been demonstrated: (i) nanostructured N-doped bcc-CrN0.05 films combining properties typically associated with both metals and ceramics, (ii) fully-dense, hard, and stress-free Ti0.39Al0.61N, (iii) single-phase cubic Ti1−xSixN with the highest reported SiN concentrations, (iv) unprecedented AlN supersaturation in single-phase NaCl-structure V1−xAlxN, and (v) a dramatic increase in the hardness, due to selective heavy-metal ion bombardment during growth, of dense Ti0.92Ta0.08N films deposited with no external heating.Ion irradiation is a key tool for controlling the nanostructure, phase content, and physical properties of refractory ceramic thin films grown at low temperatures by magnetron sputtering. However, in contrast to gas-ion bombardment, the effects of metal-ion irradiation on properties of refractory ceramic thin films have not been extensively studied due to (i) low metal-ion concentrations (a few percents) during standard direct-current magnetron sputtering (DCMS) and (ii) difficulties in separating metal-ion from gas-ion fluxes. Recently, the situation has changed dramatically, thanks to the development of high-power impulse magnetron sputtering (HiPIMS), which provides highly-ionized metal-ion plasmas. In addition, careful choice of sputtering conditions allows exploitation of gas-rarefaction effects such that the charge state, energy, and momentum of metal ions incident at the growing film surface can be tuned. This is possible via the use of pulsed substrate bias, synchronized to the metal-ion-rich port...

We perform large-scale molecular dynamics simulations of TiN deposition at 1200 K on TiN substrates consisting of under-stoichiometric (N/Ti = 0.86) misoriented grains. The energy of incoming Ti atoms is 2 eV and that of incoming N atoms is 10 eV. The simulations show that misoriented grains are reoriented during the early stages of growth, after which the film grows 001 epitaxially and is nearly stoichiometric. The grain reorientation coincides with an increase in film N/Ti ratio. As the grains reorient, additional nitrogen can no longer be accommodated, and the film composition becomes stoichiometric as the overlayer grows epitaxially. Funding Agencies|Swedish Research Council (VR) Linkoping Linnaeus Initiative LiLi-NFM [2008-6572]; Swedish Government Strategic Research Area Grant in Materials Science on Advanced Functional Materials; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation; Olle Engkvist Foundation; VinnovaVinnova [2016-05156]; Swedish Research Council (VR)Swedish Research Council [2009-00971, 2013-4018, 2014-5790]

The authors use energy- and time-dependent mass spectrometry to analyze the evolution of metal- and gas-ion fluxes incident at the substrate during high-power pulsed magnetron sputtering (HiPIMS) of groups IVb and VIb transition-metal (TM) targets in Ar. For all TMs, the time-and energy-integrated metal/gas-ion ratio at the substrate plane NMe+/NAr+ increases with increasing peak target current density J(T,peak) due to rarefaction. In addition, NMe+/NAr+ exhibits a strong dependence on metal/gas-atom mass ratio m(Me)/m(g) and varies from similar to 1 for Ti (m(Ti)/m(Ar) = 1.20) to similar to 100 for W (m(W)/m(Ar) = 4.60), with J(T,peak) maintained constant at 1 A/cm(2). Time-resolved ion-energy distribution functions confirm that the degree of rarefaction scales with m(Me)/m(g): for heavier TMs, the original sputtered-atom Sigmund-Thompson energy distributions are preserved long after the HiPIMS pulse, which is in distinct contrast to lighter metals for which the energy distributions collapse into a narrow thermalized peak. Hence, precise timing of synchronous substrate-bias pulses, applied in order to reduce film stress while increasing densification, is critical for metal/gas combinations with m(Me)/m(g) near unity, while with m(Me)/m(g) amp;gt;amp;gt; 1, the width of the synchronous bias pulse is essentially controlled by the metal-ion time of flight. The good agreement between results obtained in an industrial system employing 440 cm(2) cathodes and a laboratory-scale system with a 20 cm(2) target is indicative of the fundamental nature of the phenomena. Funding Agencies|Swedish Research Council VR [2014-5790]; Aforsk Foundation [16-359]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; Knut and Alice Wallenberg Foundation [KAW 2015.0043]

Angle-resolved x-ray photoelectron spectroscopy (AR-XPS) was used to analyze as-deposited epitaxial TiN(001) layers grown in situ. The films were grown by ultrahigh vacuum reactive magnetron sputtering onto MgO(001) at 600 °C in mixed 1:1 Ar/N2 discharges maintained at a total pressure of 0.5 Pa (3.75 × 10−3 Torr). AR-XPS spectra were obtained using incident monochromatic Al Kα radiation at 0.83401 nm. The results show that the TiN(001) surfaces are free of O and C. The Ti 2p photoelectron spectra of clean TiN are characterized by 2p3/2 and 2p1/2 lines appearing at 454.7 and 460.7 eV, each with corresponding satellite lines which are shifted ∼2.6 eV to higher binding energies.

Angle-resolved x-ray photoelectron spectroscopy (AR-XPS) was used to analyze Si3N4/TiN(001) bilayers grown by ultrahigh vacuum reactive magnetron sputter deposition onto MgO(001), with a substrate potential of −250 V, in mixed 1:1 Ar/N2 discharges maintained at a total pressure of 0.5 Pa (3.75 × 10−3 Torr). The TiN(001) films were grown at 600 °C and the 4-ML-thick Si3N4 overlayers at room temperature. AR-XPS spectra were obtained using incident monochromatic Al Kα X-radiation at 0.83401 nm. Si3N4/TiN(001) Ti 2p spectra reveal enhanced unscreened final-state satellite peaks, compared to Ti 2p spectra obtained from uncapped TiN(001), due to decreased electronic screening induced by Si3N4/TiN(001) bilayer interfacial polarization.

Angle-resolved x-ray photoelectron spectroscopy (AR-XPS) was used to analyze Si/TiN(001) bilayers grown by ultrahigh vacuum reactive magnetron sputter deposition on MgO(001), with an electrically floating substrate potential of 7 V, in mixed 1:1 Ar/N2 discharges maintained at a total pressure of 0.5 Pa (3.75 × 10−3 Torr). The TiN(001) films were grown at 600 °C and the 4-ML-thick Si overlayers at room temperature. AR-XPS spectra were obtained using incident monochromatic Al Kα x-radiation at 0.83401 nm. Si/TiN(001) Ti 2p spectra reveal reduced unscreened final-state satellite peaks compared to Ti 2p spectra obtained from uncapped TiN(001) due to increased electronic screening.

X-ray photoelectron spectroscopy (XPS) was used to analyze Ti/TiN(001) bilayers grown by ultrahigh vacuum reactive magnetron sputter deposition on MgO(001), with an electrically floating substrate potential of 7 V, in mixed 1:1 Ar/N2 discharges maintained at a total pressure of 0.5 Pa (3.75 × 10−3 Torr). The TiN(001) films were grown at 600 °C and the 4-ML-thick Ti overlayers at room temperature. XPS spectra were obtained using incident monochromatic Al Kα x-radiation at 0.83401 nm. Ti/TiN(001) Ti 2p spectra reveal reduced unscreened final-state satellite peaks compared to Ti 2p spectra obtained from uncapped TiN(001) due to increased electronic screening.

Using in situ high-temperature (1395 K), ultra-high vacuum, scanning tunneling microscopy (STM), we investigated the growth of bilayer graphene on 6H-SiC(0001). From the STM images, we measured areal coverages of SiC and graphene as a function of annealing time and found that graphene grows at the expense of SiC. Graphene domains were observed to grow, at comparable rates, at (I) graphene-free SiC step edges, (II) graphene–SiC interfaces, and (III) the existing graphene domain edges. Based upon our results, we suggest that the rate-limiting step controlling bilayer graphene growth is the desorption of Si from the substrate.

Nanoscale multilayer TiAlCN/VCN coatings with bilayer thickness Δ=2·2 nm were deposited by the combined high power impulse magnetron sputtering (HIPIMS)/unbalanced magnetron sputtering technology. The V+ HIPIMS etching produced atomically clean interface and V implantation resulting in enhanced coating adhesion LC=58 N. High resolution transmission electron microscopy and electron energy loss spectroscopy revealed that in TiAlCN/VCN, carbon forms a lateral phase between the nanolayers, producing low shear strength interfaces. This results in a well defined nanometre scale layer by layer wear mechanism, which is the key for prevention of tribofilm and consequently thick built up layer formation. In dry milling of Al 7010-T 7651 alloy, TiAlCN/VCN outperformed state of the art diamond like carbon, Cr/WC/a-CH coated and uncoated end mills by factors of 4 and 8 respectively. In turning of Ti alloys (Ti0·90Al0·06V0·04) the TiAlCN/VCN coated cemented carbide inserts produced two to three times more components (orthopaedic implants), as compared to uncoated tools.

Pseudobinary V0.5Mo0.5Nx(111) alloys with the B1-NaCl crystal structure are grown on Al2O3(0001) substrates in an ultra-high-vacuum system by reactive magnetron sputter deposition in mixed Ar/N2 atmospheres at temperatures Ts between 100 and 900 °C. Nitrogen-to-metal, N/(V + Mo), fractions x vary monotonically from 0.9 ± 0.1 with Ts = 100 °C to 0.4 ± 0.1 at Ts = 900 °C. Nitrogen loss at higher growth temperatures leads to a corresponding decrease in the relaxed lattice parameter ao from 4.21 ± 0.01 A at Ts = 300 °C to 4.125 ± 0.005 A with Ts = 900 °C. Scanning electron micrographs of cube-corner nanoindents extending into the substrate show that the films are relatively ductile, exhibiting material pile-up (plastic flow) around the indent edges. Nanoindentation hardnesses H and elastic moduli E, obtained using a calibrated Berkovich tip, of V0.5Mo0.5Nx(111) layers increase with increasing Ts (decreasing x) from 15 ± 1 and 198 ± 5 GPa at 100 °C to 23 ± 2 and 381 ± 11 GPa at 900 °C. These values are lower than the corresponding results obtained for the 001-oriented V0.5Mo0.5Nx films. In addition, film wear resistance increases with increasing Ts, while the coefficient of friction, under 1000 μN loads, is 0.09 ± 0.01 for all layers.Pseudobinary V0.5Mo0.5Nx(111) alloys with the B1-NaCl crystal structure are grown on Al2O3(0001) substrates in an ultra-high-vacuum system by reactive magnetron sputter deposition in mixed Ar/N2 atmospheres at temperatures Ts between 100 and 900 °C. Nitrogen-to-metal, N/(V + Mo), fractions x vary monotonically from 0.9 ± 0.1 with Ts = 100 °C to 0.4 ± 0.1 at Ts = 900 °C. Nitrogen loss at higher growth temperatures leads to a corresponding decrease in the relaxed lattice parameter ao from 4.21 ± 0.01 A at Ts = 300 °C to 4.125 ± 0.005 A with Ts = 900 °C. Scanning electron micrographs of cube-corner nanoindents extending into the substrate show that the films are relatively ductile, exhibiting material pile-up (plastic flow) around the indent edges. Nanoindentation hardnesses H and elastic moduli E, obtained using a calibrated Berkovich tip, of V0.5Mo0.5Nx(111) layers increase with increasing Ts (decreasing x) from 15 ± 1 and 198 ± 5 GPa at 100 °C to 23 ± 2 and 381 ± 11 GPa at 900 °C. These values are lower t...

Epitaxial TiN layers, 0.3 μm thick, are grown on MgO(001) in the absence of applied substrate heating using very high flux, low-energy (below the lattice atom displacement threshold), ion irradiation during reactive magnetron sputter deposition in pure N 2 discharges. High-resolution x-ray diffraction, reciprocal lattice maps, and transmission electron microscopy analyses reveal that the TiN(001) films grow with an (001) TiN ||(001) MgO and [100] TiN ||[100] MgO orientation relationship to the substrate. The layers are fully coherent with no detectable misfit dislocations. For comparison, TiN/MgO(001) films grown at temperatures of 700–850 °C under similar conditions, but with no intentional ion irradiation, are fully relaxed with a high misfit dislocation density. Thus, the present results reveal that intense low-energy ion irradiation during film growth facilitates high adatom mobilities giving rise to low-temperature epitaxy, while the low growth temperature quenches strain-induced relaxation and suppresses misfit dislocation formation.

We use molecular dynamics (MD) based on the modified embedded atom method (MEAM) to determine diffusion coefficients and migration pathways for Ti and N adatoms (Ti-ad and N-ad) on TiN(111). The reliability of the classical model-potential is verified by comparison with density functional theory (DFT) results at 0 K. MD simulations carried out at temperatures between 600 and 1800 K show that both Ti-ad and N-ad favor fcc surface sites and migrate among them by passing through metastable hcp positions. We find that N-ad species are considerably more mobile than Ti-ad on TiN(111); contrary to our previous results on TiN(001). In addition, we show that lattice vibrations at finite temperatures strongly modify the potential energy landscape and result in smaller adatom migration energies, E-a = 1.03 for Ti-ad and 0.61 eV for N-ad, compared to 0 K values E-aOK = 1.55 (Ti-ad) and 0.79 eV (N-ad). We also demonstrate that the inclusion of dipole corrections, neglected in previous DFT calculations, is necessary in order to obtain the correct formation energies for polar surfaces such as TiN(111). (C) 2016 Elsevier B.V. All rights reserved. Funding Agencies|Knut and Alice Wallenberg Foundation [2011.0094]; Swedish Research Council (VR) [2014-5790]; Linkoping Linnaeus Initiative LiLi-NFM [2008-6572]; Swedish Government Strategic Research Area Grant in Materials Science on Advanced Functional Materials through Swedens innovation agency VINNOVA [MatLiU 2009-00971]

Epitaxial metastable Hf 1 − x Al x N alloys with 0 ≤ x ≤ 0.50 were grown on MgO(001) substrates at 600 °C by ultrahigh vacuum reactive magnetron sputtering from Hf and Al targets in 90% Ar + 10% N 2 discharges at 7 mTorr. X-Ray diffraction and cross-sectional transmission electron microscopy show that Hf 1 − x Al x N alloys are single crystals with the B1–NaCl structure. Rutherford backscattering spectroscopy investigations reveal that all films are slightly overstochiometric with N / (Hf + Al) = 1.05 ± 0.05. The relaxed lattice parameter decreased linearly from 0.4519 nm with x = 0 to 0.4438 nm with x = 0.50, compared to 0.4320 nm expected from the linear Vegard's rule. We find a metastable single phase field that is remarkably broad given the large lattice mismatch (≃ 9%) between the two alloy components. Alloying HfN with AlN leads to an increase in hardness (≃ 30% to 32.4 ± 0.7 GPa), as well as nanostructured compositional modulations due to the onset of spinodal decomposition.

CrN films were prepared on steel substrates by a hybrid method utilizing filtered cathodic arc for Cr ion pretreatment and magnetron sputtering for coating deposition. During pretreatment the substrates were biased to −1200V and exposed to filtered chromium plasma. The substrate-coating interface formed during the pretreatment contained a Cr-enriched modified layer with composition that was strongly influenced by the temperature of the substrate as observed by scanning transmission electron microscopy—energy dispersive spectroscopy. The modified layer had a nanocrystalline morphology and thickness of 15nm. The path of formation of the layer is linked to the combined action of implantation, diffusion, and resputtering. The resulting adhesion of 3μm thick CrN films was very high with scratch test critical load values of 83N. The morphology of the films was smooth without large scale defects and the microstructure was columnar. The coatings behaved well in dry sliding tests with very low wear coefficients of...

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Epitaxial CoSi2 layers, which are phase pure but contain {111} twins, are grown on Si(001) at 700 °C by reactive deposition epitaxy. Transmission electron microscopy analyses show that the initial formation of CoSi2(001) follows the Volmer–Weber mode characterized by the independent nucleation and growth of three-dimensional islands whose evolution we follow as a function of deposited Co thickness tCo in order to understand the origin of the observed twin density. We find that there are two families of island shapes: inverse pyramids and platelets. The rectangular-based pyramidal islands extend along orthogonal 〈110〉 directions, bounded by four {111} CoSi2/Si interfaces, and grow with a cube-on-cube orientation with respect to the substrate: (001)CoSi2||(001)Si and [100]CoSi2||[100]Si. Platelet-shaped CoSi2 islands are bounded across their long 〈110〉 directions by {111} twin planes (i.e. {111}(001)CoSi2||{111}Si) and their narrow 〈110〉 directions by {511}CoSi2||{111}Si interfaces. The top and bottom surfaces are {22¯1}, with {22¯1}CoSi2||(001)Si, and {1¯1¯1}, with {1¯1¯1}CoSi2||{11¯1}Si, respectively. The early stages of film growth (tCo ≤ 13 A) are dominated by the twinned platelets due to a combination of higher nucleation rates resulting from a larger number of favorable adsorption sites in the Si(001)2 × 1 surface unit cell and rapid elongation of the platelets along preferred 〈110〉 directions. However, at tCo ≥ 13 A island coalescence becomes significant as orthogonal platelets intersect and block elongation along fast growth directions. In this regime, where both twinned and untwinned island number densities have saturated, further island growth becomes dominated by the untwinned islands. A continuous epitaxial CoSi2(001) layer, with a twin density of 2.8 × 1010 cm− 2, is obtained at tCo = 50 A.