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.

This paper presents a study on pulsed plasma-chemical synthesis of fluorine- and gold-doped silicon oxide nanopowder. The gold- and fluorine-containing precursors were gold chloride (AuCl3) and sulphur hexafluoride (SF6). Pulsed plasma-chemical synthesis is realized on the laboratory stand, including a plasma-chemical reactor and TEA-500 electron accelerator. The parameters of the electron beam are as follows: 400-450keV electron energy, 60ns half-amplitude pulse duration, up to 200J pulse energy, and 5cm beam diameter. We confirmed the composite structure of SixOy@Au by using transmission electron microscopy and energy-dispersive spectroscopy. We determined the chemical composition and morphology of synthesized SixOy@Au and SixOy@F nanocomposites. The material contained a SixOy@Au carrier with an average size of 50-150nm and a shell of fine particles with an average size of 5-10nm.

Al2O3 alloyed with Cr is an important material for the tooling industry. It can be synthesized from an arc discharge using Al-Cr cathodes in an oxygen atmosphere. Due to formation of Al-rich oxide islands on the cathode surface, the arc process stability is highly sensitive to oxygen pressure. For improved stability, the use of Al0.70Cr0.25Si0.05 cathodes has previously been suggested, where Si may reduce island formation. Here, we have investigated the effect of Si by comparing plasma generation and thin film deposition from Al0.7Cr0.3 and Al0.7Cr0.25Si0.05 cathodes. Plasma ion composition, ion energies, ion charge states, neutral species, droplet formation, and film composition have been characterized at different O-2 flow rates for arc currents of 60 and 90 A. Si and related compounds are detected in plasma ions and in plasma neutrals. Scanning electron microscopy and energy dispersive X-ray analysis show that the cathode composition and the film composition are the same, with Si present in droplets as well. The effect of Si on the process stability, ion energies, and ion charge states is found to be negligible compared to that of the arc current. The latter is identified as the most relevant parameter for tuning the properties of the reactive discharge. The present work increases the fundamental understanding of plasma generation in a reactive atmosphere, and provides input for the choice of cathode composition and process parameters in reactive DC arc synthesis.

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. 

An inherent property of cathodic arc is the generation of macroparticles, of a typical size ranging from submicrometer up to a few tens of mu m. In this work, we have studied macroparticle generation from a Mo0.78Cu0.22 cathode used in a dc vacuum arc discharge, and we present evidence for super-size macroparticles of up to 0.7mm in diameter. All analyzed particles are found to be rich in Mo (>= 98 at. %). The particle generation is studied by visual observation of the cathode surface during arcing, by analysis of composition and geometrical features of the used cathode surface, and by examination of the generated macroparticles with respect to shape and composition. A mechanism for super-size macroparticle generation is suggested based on observed segregated layers of Mo and Cu identified in the topmost part of the cathode surface, likely due to the discrepancy in melting and evaporation temperatures of Mo and Cu. The results are of importance for increasing the fundamental understanding of macroparticle generation, which in turn may lead to increased process control and potentially provide paths for tuning, or even mitigating, macroparticle generation. (C) 2016 AIP Publishing LLC.

Thin films deposited with unfiltered DC arc plasma from Ti, Ti0.75Al0.25, Ti0.50Al0.50, Ti0.30Al0.70, and Al cathodes were characterized with a scanning electron microscope for quantification of extent of macroparticle incorporation. Depositions were performed in N-2 atmosphere in the pressure range from 10(-6) Torr up to 3 . 10(-2) Torr, and the formation of cathode surface nitride contamination was identified from X-ray diffraction analysis. Visual observation and photographic fixation of the arc spot behavior was simultaneously performed. A reduction in macroparticle generation with decreasing Al content and increasing N-2 pressure was demonstrated. A correlated transformation of the arc from type 2 to the type 1 was visually detected and found to be a function of N-2 pressure and at of Al in the cathode. For the Ti cathode, no arc transformation was detected. These observations can be explained by a comparatively high electrical resistivity and high melting point of Al rich surface nitrides, promoting an arc transformation and a reduction in macropartide generation. (C) 2015 Elsevier B.V. All rights reserved.

DC arc plasma from Ti, Al, and Ti(1-x)A(l)x (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes has been characterized with respect to plasma chemistry (charged particles) and charge-stateresolved ion energy for Ar and N-2 pressures in the range 10(-6) to 3 x 10(-2) Torr. Scanning electron microscopy was used for exploring the correlation between the cathode and film composition, which in turn was correlated with the plasma properties. In an Ar atmosphere, the plasma ion composition showed a reduction of Al of approximately 5 at.% compared to the cathode composition, while deposited films were in accordance with the cathode stoichiometry. Introducing N-2 above similar to 5 x 10(-3) Torr, lead to a reduced Al content in the plasma as well as in the film, and hence a 1:1 correlation between the cathode and film composition cannot be expected in a reactive environment. This may be explained by an influence of the reactive gas on the arc mode and type of erosion of Ti and Al rich contaminations, as well as on the plasma transport. Throughout the investigated pressure range, a higher deposition rate was obtained from cathodes with higher Al content. The origin of generated gas ions was investigated through the velocity rule, stating that the most likely ion velocities of all cathode elements from a compound cathode are equal. The results suggest that the major part of the gas ions in Ar is generated from electron impact ionization, while gas ions in a N-2 atmosphere primarily originate from a nitrogen contaminated layer on the cathode surface. The presented results provide a contribution to the understanding processes of plasma generation from compound cathodes. It also allows for a more reasonable approach to the selection of composite cathode and experimental conditions for thin film depositions. (C) 2015 AIP Publishing LLC.

DC arc plasmas from Al, Ti, Cu, Mo, and W cathodes have been characterized with respect to plasma chemistry and charge-state-resolved ion energy. The evaluated average ionization energies in the plasmas were found to be linearly correlated with the kinetic ion energies. This was further supported by evaluation of previously published data for 42 elements. A comparison of the total ion kinetic energy distribution and the corresponding ion charge state distribution, as defined by the ionization energies of the constituent ions, showed close to equivalent shapes and widths, for all cathodes analyzed. This suggests that the energy provided for ionization and acceleration varies simultaneously during plasma generation in the arc spot. The presented results provide a link between the ionization and acceleration processes, and may provide further insight into the fundamentals of cathode spot evolution and plasma generation. (C) 2015 AIP Publishing LLC.

The paper presents the results of current measurements for the electron beam, propagating inside a drift tube filled in with a gas mixture (Ar and N-2). The experiments were performed using the TEA-500 pulsed electron accelerator. The main characteristics of electron beam were as follows: 60 ns pulse duration, up to 200 J energy, and 5 cm diameter. The electron beam propagated inside the drift tube assembled of three sections. Gas pressures inside the drift tube were 760 +/- 3, 300 +/- 3, and 50 +/- 1 Torr. The studies were performed in argon, nitrogen, and their mixtures of 33%, 50%, and 66% volume concentrations, respectively. (C) 2015 AIP Publishing LLC.

We have studied the utilization of TiB2 cathodes for thin film deposition in a DC vacuum arc system. We present a route for attaining a stable, reproducible, and fully ionized plasma flux of Ti and B by removal of the external magnetic field, which leads to dissipation of the vacuum arc discharge and an increased active surface area of the cathode. Applying a magnetic field resulted in instability and cracking, consistent with the previous reports. Plasma analysis shows average energies of 115 and 26 eV, average ion charge states of 2.1 and 1.1 for Ti and B, respectively, and a plasma ion composition of approximately 50% Ti and 50% B. This is consistent with measured resulting film composition from X-ray photoelectron spectroscopy, suggesting a negligible contribution of neutrals and macroparticles to the film growth. Also, despite the observations of macroparticle generation, the film surface is very smooth. These results are of importance for the utilization of cathodic arc as a method for synthesis of metal borides. (C) 2015 AIP Publishing LLC.