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The effect of bias voltages (40 V, 80 V, and 40/60/80 V) on microstructure and electrochemical properties of arc-PVD CrN coatings were evaluated. Increasing the bias voltage produced microstructural changes, from well-defined columns to columnar grains, and increased defect size. The electrochemical response proved susceptible to the defect type. Nano-droplets promoted the formation of oxides, while large pores allowed the migration of the electrolyte to the substrate/CrN interface. An impedance equivalent circuit based on the Bisquert transmission line was proposed to fit the experimentally obtained impedance spectra. The equivalent circuit allowed correlating the coating electrochemical response to the defect densities and sizes. Samples deposited with 40 V showed the lowest corrosion current (0.05 μA/cm2 ± 0.01), which was supported by the highest resistances to the transport of ions through the pores (Rp = 1047 ± 88 kΩꞏcm2). Films obtained with 80 V reduced Rp values by two magnitude orders compared to CrN 40 V. The increase of pore resistance in CrN 40 V was associated with the oxidation of nano-droplets (proposed auto-protection phenomenon), which blocks open pinholes due to the smallest average size of defects. Tailoring a gradual increase of the bias voltage (40/60/80 V) preserves the auto-protection mechanism of droplets and improves the surface finish of the coating.

Mechanical and tribological properties of titanium nitride, zirconium nitride, and (TiN/ZrN)n multilayers were studied to examine the potential of Kelvin probe force microscopy (KPFM) to identify wear mechanisms. Crystalline structure, chemical composition, residual stress, and the mechanical properties showed that the coatings are iso-structural polycrystalline multilayers, with a reduction of grain size, crystallite size, and compressive stress; however, hardness increased with increase in the number of the bilayers. Pin-on-disc test was used for tribological evaluation, and wear tracks were analyzed using field-emission scanning electron microscopy/energy dispersed spectroscopy (FE-SEM/EDS) and KPFM. The increase in mechanical properties generated predominantly abrasive wear mechanisms. Abrasive and adhesive wear mechanisms differentiated by KPFM demonstrated that fragile wear mechanisms presented differences in capacitance and surface potential and that the method is sensitive when the adhered material presents differences in chemical composition. We have demonstrated KPFM to be a promising technique to study tribo-oxidation processes, providing experimental evidence to understand the wear mechanisms at nanometric scales.

A good understanding of the nonlinearity mechanism in SAW devices is a crucial aspect in the filter stage. Nonlinear intermodulation distortion (IMD) may lead to spurious signals falling into the receiver band and limiting its sensitivity. Identify the dominant source of nonlinearity specially at high-power is important for a good prediction of the filter nonlinear response. In this work, third-order intermodulation (IMD3) products in TC-SAW (Temperature Compensated-SAW) devices are presented. Within this work we apply the previously developed Input-Output Equivalent Sources (IOES) method to compute nonlinearities of more complex structures such as ladder-type and CRF (Coupled Resonator Filter) filter structures. This work was supported in part by the Spanish Government through grant PID2020-118410RB-C21. Research was also supported by the Secretary of Universities and Research of the Generalitat de Catalunya and the European Social Fund through grant FI_B-00136.

Summary Two experiments were conducted to evaluate the effects of dietary amino acid density and exogenous protease inclusion on growth performance and amino acid digestibility in poultry. In experiment 1, Cobb 500 broiler chicks (n = 480) were fed to 21 d of age. Treatments were arranged as a 2 × 4 factorial design with main effects of commercial protease (with or without) and amino acid density which corresponded to approximately 95, 97.5, 100, or 102.5% of breeder recommendations for digestible Lys. In experiment 2, hybrid turkey poults (n = 780) were fed diets formulated to provide low or adequate amino acid density (approximately 91 and 100% of the NRC-recommended requirement for digestible Lys, respectively) with each diet being fed with or without an exogenous protease. Poults received experimental diets from day 1 to 42 of age. Growth performance metrics were calculated from pen weights and feed consumption recorded throughout each experiment, and digestibility data were obtained from analysis of ileal contents. Data were analyzed using SAS 9.4 with pen as the experimental unit and pen location as the blocking factor. Results of these experiments demonstrated broilers fed 1.12 and 1.21% digestible Lys diets with added protease had a 2-point improvement in feed conversion ratio (FCR) compared with chicks fed these diets without protease. Increasing amino acid density improved FCR in broilers and poults and improved BW, ADG, and ADFI in poults. There was no evidence that added protease had an effect on BW, ADG, or ADFI in broilers or poults. Finally, ileal amino acid digestibility was not affected by amino acid density or protease inclusion for either 20-day-old broiler chicks or 42-day-old turkey poults.

Improving power handling and lifetime are key assets to ensure device performance and reliability. SAW resonators composed by very thin cross-section inter-digital transducer (IDT) structures make difficult to control the current density and thus acoustomigration plays and important role since degradation of the metallization is one of the main failure modes. The motivation of this work is to monitor and characterize the resonator behavior even at high powers levels that can damage the device. The method is based on a feed-forward-based technique to measure the reflection coefficient of SAW resonators under a fixed-frequency high power heating (HPH) signal. This work was supported in part by the Spanish Government through grants TEC2017-84817-C2-2-R, TEC2017-88343-C4-2-R and 2017 SGR-813. Research was also supported by the Secretary of Universities and Research of the Generalitat de Catalunya and the European Social Fund through grant FI_B-00136.

Summary Repsol has set up a commitment to achieve net zero emissions by 2050. This decarbonization path would require, initially, Carbon Capture Storage projects; which requires a compulsory subsurface storage. This paper will focus on main lessons learned that have been analyzed from the original Geological Carbon Storage screening process (basin or regional scale), a start up process to qualify potential subsurface candidate for further characterization feasibility analysis. This screening, first step in “Green Exploration”, included as an acceleration driver both depleted oil & gas fields and drilled wells (dry hole/ saline aquifer potential). Main lessons learned are aligned with technical concepts to be considered and specific risk assessment proposal at this project’s phase. It is paramount to align screening results (methodology/deliverables) with mandatory decision process that, if positively qualified, would set up the road map for further visualization to definition methodologies.

Summary Current Upstream decarbonization roadmap would require Carbon Capture Storage projects not just to reduce emissions balance, but to achieve negative emissions. First step in this process of “green exploration”, in analogy with convention exploration, will be to screen out favorable basins. Main objective of this “green exploration” is to analyze (feasibility study) which subsurface options could progress on the project management decision process (Carbon Capture & Storage, CCS subsurface). There are evident advantages in mature Oil & Gas basins where producing fields, close to depletion, aligned with dry hole (potential saline aquifer’s) could speed up screening process feasibility. Based on a prior positive screening a project (depleted Oil & Gas Field) could be sanctioned for next milestone: computed 3D Geological Static model, which will integrate all available Geological, Geophysical & Logging data with required interpretation. This paper summarizes main lessons learned gathered from in-house 3D geological modeling of depleted oil & gas fields and saline aquifers (upside green exploration in shallow producing fields horizons). Mentioned 3D Geological Static model has proven to be the corner stone of any further CO2 storage feasibility analysis and a starting point to explore for additional storage resources, outside producing reservoirs.

Vanadium dioxide (VO2) is widely recognized as a thermochromic material with great potential for application in smart glazing for energy-efficient buildings. The monoclinic (M1) VO2 phase undergoes a first-order reversible phase transition from the semiconductor to the rutile metallic state. In this study, an M1 VO2 porous film was synthesized via a polymer-assisted sol-gel route. Processing parameters, such as drying and reduction temperatures, were varied to evaluate their influence on the thermochromic behavior of VO2 and to determine the necessary trade-off between a significant thermochromic effect and high luminous transmittance. Film-silica glass-film systems with luminous transmittance close to 80% and IR solar modulation ability as large as 20% were prepared. By tracking the optical constants of the films during the thermochromic process, the changes produced at the microscopic level in the material could be correlated with its macroscopic behavior when used as an energy-saving material., Y J. Outon acknowledges the support by the Spanish Ministerio de Educacion y Cultura through grant FPU19-02638. M. Dominguez ac-knowledges the support by the Spanish Ministerio de Ciencia, Innovacion y Universidades under project EQC2018-004704-P. The authors thank the University of Cadiz and IMEYMAT for financing the mutual facilities available at the UCA R&D Central Services (SC-ICYT) and the IMEYMAT Institute project reference PLP2020335-1 respec-tively. The authors also acknowledge J. Gonzalez and F. Delgado for their assistance in the preparation of the STEM specimens.

Understanding the mechanism of nonlinearity in SAW/BAW devices is growing up in importance because these, even being weak, can cause desensitization of the receivers and limiting their performance. Proper nonlinear distributed models have been extensively used, usually running Harmonic Balance (HB) simulations being in some cases very time consuming. The motivation of this work is to apply a new method of analysis for the simulation of harmonics (H) and intermodulation products (IMD) generation in SAW devices. The method is called the Input-Output Equivalent Sources (IOES) and it allows extremely fast and robust simulations of large distributed weak nonlinear circuits. This work was supported in part by the Spanish Gov. through grants TEC2017-84817-C2-2-R, TEC2017-88343-C4-2-R and 2017 SGR-813. Research wasalso supported by the Secretary of Universities and Research of the Generalitatde Catalunya and the European Social Fund through grant FI_B-00136.

This is the pre-peer reviewed version of the following article: González‐Rodríguez, M., Collado, C., González‐Arbesú, J. M., Mateu, J., Montoro, G., & Gilabert, P. L. (2021). Tone injection‐based cancellation technique for nonlinear distortion reduction of modulated signals in BAW resonators. Microwave and Optical Technology Letters, 63(3), 781-786, which has been published in final form at https://onlinelibrary.wiley.com/doi/10.1002/mop.32670. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. A technique for the reduction of third-order intermodulation distortion (IMD3) occurring in bulk acoustic wave (BAW) filters and multiplexers is presented. The method consists of using the intrinsic second-order intermodulation distortion generated by BAW filters and multiplexers themselves by injecting an externally controlled amplitude and phase modulated signal at low frequency to compensate for the IMD3. The proposed technique has been experimentally verified by performing IMD3 measurements in a single BAW resonator subject to several modulated signals under a nonlinear scenario. Secretary of Universities and Research of the Generalitat de Catalunya and the European Social Fund, Grant/Award Number: FI_B-00136; Spanish Government, Grant/Award Numbers: 2017 SGR-813,TEC2017-84817-C2-2-R, TEC2017-88343-C4-2-R

Hard coatings are continuously improved due to the industrial needs and urgency to reduce the environmental impact of manufacturing processes. For these reasons, scientists seek hard coatings resistant to high mechanical and thermal loads under extreme working conditions (i.e., dry machining), which is why Hf and other rare earth metals have been added to the metastable c-AlxTi(1-x)N nitrides. In the present investigation, Hf-doped c-Al0.64Ti0.36N was deposited in a 2- & 3-axis rotation system using a semi-industrial coater. For this purpose Hf-pins were fixed in Al/Ti targets that produced coatings with ~0.2 at. % Hf-contents homogeneously dispersed. Hf effect on the crystalline state and microstructure, mechanical properties, high-temperature resistance, and the tribological performance of the coating in an Ar-jet at 900 °C were analyzed. It was found that the Hf-doped Al0.64Ti0.36N 5.07 μm thick-layer was mainly cubic fcc + traces of the hcp phases and displayed higher mean hardness (36 GPa) and E-module (416 GPa) than the coating without Hf (h = 32 GPa and E = 402 Pa). The Hf-containing nitride oxidizes dynamically during the high-temperature tribology testing and produces t-Ti2O3 & o-Al2TiO5 after short exposure periods (2.5–5 min), which strongly affected the CoF, before evolving to thermodynamically stable α-Al2O3 & anatase TiO2 between 10 & 30 min in the Ar-flow, thus resulting in the relative stability of the CoF. The mechanical evaluation of the oxidized coatings indicates that a specific oxide thickness must be reached to avoid catastrophic system damage at high normal loads.

The development of homogeneous, dense, and smooth hard coatings is a challenging task, and that is why the high power impulse magnetron sputtering (HiPIMS) method has been proposed to tailor and control the microstructure through the modification of the duty cycle. HiPIMS offers extensive possibilities to obtain good quality films with fine and dense morphology. In this work, the synthesis of CrxN coatings by HiPIMS with the variation of duty cycle (τ = 2.7% and 12%), substrate bias voltages (Vb = −150 and − 250 V), and gas ratio (fN2/Ar = 0.2 and 0.4) was evaluated. The influence of these processing conditions on the chemical composition, microstructure, and adhesion of HiPIMS CrxN was investigated. A significant increment of the deposition rate and the chromium content in the CrxN coatings is observed at τ = 12%; meanwhile, at τ = 2.7%, films showed high nitrogen content. The crystalline phases like α-Cr + h-Cr2N, h-Cr2N, and h-Cr2N + c-CrN were identified in the as-deposited films. The Cr-rich coatings presented faceted columns with cauliflower-like surface morphology, while the growth of the h-Cr2N phase caused a grain size refinement and a denser microstructure. The surface morphology of the h-Cr2N coatings changed from pyramidal to stacked pyramids with the reduction of the duty cycle. The transformation of the h-Cr2N to c-CrN leads to highly dense columnar microstructures with a fine granular morphology and a smooth surface. The duty cycle strategies can be applied to develop a particular microstructure with specific chemical composition and crystallographic phases, resulting in an alternative method to produce graded or multilayer systems. The duty cycle reduction increases the interfacial adhesion strength of the coatings.

This paper performs a comprehensive nonlinear modeling of a Bulk Acoustic Wave (BAW) duplexer operating at the band 7 of the LTE wireless communication standard. The modeling starts by an accurate characterization of the resonators forming the filters by performing measurements of the second harmonic (H2). The modeling of individual resonators has then been used to predict second order nonlinear manifestations occurring in a real duplexer. These are H2, second order intermodulation products (IMD2), for the case where a jamming signal is set to low frequencies (IMD2-Low) and when the jamming signal is set to high frequencies (IMD2-High). Predicted results are then validated with real measurements. The authors would like to thank Qorvo Inc. for providing the on-wafer measurements that appear in this article. Work supported in part through grants TEC2017-84817-C2-2-R, TEC2017-88343-C4-2-R and 2017 SGR 813

As the power requirements in BAW filters steadily increase, thermal behaviour emerges as a key asset to ensure device performance and reliability. Under these conditions, self-heating mechanisms drive to possible situations where the filters no longer meet the electrical specifications. In addition to that, the evaluation of the heat spreading might help to define the resonators and pillars distribution along with the overall performance of current BAW filters. In the past, numerical methods based on FEM have been used to study the temperature distribution under high-power (HP) signals, lacking efficiency in terms of computational time. The motivation of this work is to describe an analytical method that is able to simulate very fast, without the need of costly FEM simulation, the heat spreading in a filter according to the spatial distribution of the resonators. This work was supported in part by the Spanish Gov. through grants TEC2017-84817-C2-2-R, TEC2017-88343-C4- 2-R and 2017 SGR-813. Research was also supported by the Secretary of Universities and Research of the Generalitat de Catalunya and the European Social Fund through grant FI_B00136

An experimental-numerical methodology for failure analysis of the c-Al0.66Ti0.34N/Interface/M2 steel coating system is proposed here. This c-Al0.66Ti0.34N coating was deposited by the arc-PVD technique. The values of the elastic modulus, the fracture energy release rate and the nano-hardness of the coating were obtained by nanoindentation. Normal and shear stress limits of the interface, as well as the adhesive and cohesive critical loads, were measured with the scratch test method. A finite element analysis, using the experimental mechanical properties, was carried out to understand the relationship between the irreversible work vs. depth curve and the mechanical failure evolution of the coating-substrate system, associating the pop-in with nucleation, crack growth and cracking pattern. Extended finite element method (XFEM) was applied for modeling of the mechanical behavior of the coating; the cohesive zones approach was applied for modeling the interface and the Ramberg-Osgood law for modeling the substrate. This approach proposes an experimental-numerical methodology for failure analysis of hard coatings (monolithic body) allowing to calculate fracture energy of the coating material and to model cracking patterns caused by contact mechanics. This work is the first step to answer questions about multi-scale approaches for multi-functional multi-layer coatings to push their enhancements and further applications.

Currently employed in aerospace, defense, oil, and gas applications, Inconel 718 (IN718) is an indispensable alloy with excellent thermo-mechanical properties and hot corrosion resistance. Inconel (IN718) has become the gold standard to manufacture turbine blades, bearing housing parts, compressor seals, drive couple gears, side pocket mandrels, wellheads, packers, and safety valves. Additive Manufacturing (AM) or 3D printing technology is a promising alternative to fabricate and repair nickel-based superalloy components, characterized by challenging processing through conventional methods due to the mechanical strength of the alloys or the geometric complexity of the piece. Furthermore, many applications require surface protection features, such as high hardness, corrosion, and wear resistance. These properties can be achieved by applying hard coatings and/or surface thermochemical treatments such as plasma nitriding. This study reports the effect of plasma nitriding applied on Laser Powder Bed Fusion (LPBF) additively manufactured IN718. Depending on the time, the treatment produced a 1.5–2.8 μm nitrided protective bi-layer composed by an outer CrN containing layer followed by an inner austenitic expanded γN layer. The growing kinetics analysis shows that the nitriding process follows a parabolic behavior. The nitriding process also increases the surface roughness as a result of case hardening formation reaching ~ 60 nm within 2 h. No measurable wear on the plasma nitrided additively manufactured IN718 alloy was recorded.

The presence of critical resonances in microwave power amplifiers has a negative impact on its behavior and performance. These critical resonances are usually predicted from pole-zero stability simulations. In this paper, a different and less demanding approach for the circuit designer is proposed. It is based on performing noise simulations of the amplifier and observing the rise in the noise spectrum that happens when the system has low damping poles. Critical resonance detection is simplified since no additional probes have to be inserted in the circuit and no post-processing for pole-zero analysis is required. The technique is applied to two amplifier prototypes fabricated in microstrip hybrid technology and the results are compared with the conventional pole-zero approach.

This work presents a new technique to cancel third-order intermodulation distortion (IMD3) by using a low frequency injected tone to generate a second-order intermodulation product (IMD2) that fall exactly at the same frequency of the undesired IMD3. The phase and amplitude of the injected tone are controlled to cancel out the IMD3. A proper characterization and a good modeling are needed to demonstrate the concept. Narrow band characterization and modeling of second harmonic (H2) and IMD3 in a Bulk Acoustic Wave (BAW) resonator has been done to evaluate the nonlinear contribution of each material composing the resonator and to identify the dominant nonlinear terms. The concept of this technique will be demonstrated by doing measurements of an on-wafer resonator. The measurement system, including the cancellation procedure, will be described. The cancellation achieved with this technique is in good agreement with the simulations.