Single Bath Research Articles

Optimized finite-time information machine

We analyze a periodic optimal finite-time two-state information-driven machine that extracts work from a single heat bath exploring imperfect measurements. Two models are considered, a memory-less one that ignores past measurements and an optimized model for which the feedback scheme consists of a protocol depending on the whole history of measurements. Depending on the precision of the measurement and on the period length, the optimized model displays a phase transition to a phase where measurements are judged as non-reliable. We obtain the critical line exactly and show that the optimized model leads to more work extraction in comparison to the memory-less model, with the gain parameter being larger in the region where the frequency of non-reliable measurements is higher. We also demonstrate that the model has two second law inequalities, with the extracted work being bounded by the change of the entropy of the system and by the mutual information.

Extracting work from a single heat bath: a case study of a Brownian particle under an external magnetic field in the presence of information.

Work can be extracted from a single bath beyond the limit set by the second law of thermodynamics by performing measurement on the system and utilizing the acquired information. This imposes an upper bound on extracted work and maintains a generalized (i.e., with information) second law. As an example, we studied a Brownian particle confined in a two-dimensional harmonic trap in the presence of a magnetic field, whose position coordinates are measured with finite precision. Two separate cases are investigated in this study: (A) moving the center of the potential and (B) varying the stiffness of the potential. Optimal protocols that extremize the work in a finite-time process are explicitly calculated for these two cases. For case A, we show that even though the optimal protocols depend on magnetic field, surprisingly, extracted work is independent of the field. For case B, both the optimal protocol and the extracted work depend on the magnetic field. However, the presence of a magnetic field always reduces the extraction of work for the latter case.

A new approach to fabricating magnetic multilayer nanowires by modifying the ac pulse electrodeposition in a single bath

This work focused on the development of a new single bath technique to fabricate compositionally modulated Co/Cu, CoFe/Cu and Fe/Cu multilayer nanowires in nanoporous alumina templates prepared by the hard and mild anodization methods. The approach was based on ac pulse electrodeposition, employing successive cycles of alternating continuous and pulsed sine waves with designated off-time between pulses and reduction/oxidation voltages. The substantial control over the composition of each segment was achieved by simultaneous change in the off-time between pulses and the ac deposition voltage. The multilayered nature of the nanostructures was substantiated by transmission electron microscopy. Each layer thickness was also nearly uniform, and could be readily adjusted by the number of pulses. The proposed method facilitates the fabrication of various multilayer nanowires in a single bath, which speeds up the fabrication process and is desirable for their application in nanodevices and nanoelectronics. The effect of magnetic layer thickness on the magnetic behaviour was also studied. Decreasing the magnetic layer thickness caused the parallel coercivity and squareness values to approach those measured in the perpendicular direction. The magnetic easy axis changed from parallel to nearly perpendicular to the nanowire axis, depending on the magnetic layers' aspect ratio and shape anisotropies.

Invited: Reactive Bonding with Integrated Reactive and Nano Scale Energetic Material Systems (iRMS): State-of-the-Art and Future Development Trends

The latest trends in micro systems technology focus on the integration of new materials, such as metals or polymers, in a smart system [1]. Furthermore, most of the Micro-Electro-Mechanical-Systems (MEMS) devices need strong and hermetically sealed packages, which guarantee a reliable functionality [2]. In general, the hermetic MEMS packaging is done by wafer bonding, such as glass-frit and anodic bonding [3]. These bonding procedures operate at high bonding temperatures where all components are heated up. This can cause damage to temperature sensitive components. One possible solution to reduce the bonding temperature is the so called reactive bonding. This technique uses an internal heating produced in reactive and nano scale energetic material systems (RMS) [4]. Nevertheless, the main principle behind these nano energetic materials is that at least two nano scale educts (in our case A and B) undergo exothermic intermixing to form products. This heat is produced in form of a self-propagating exothermic reaction (SER). This paper focuses on the integration of the RMS, so called iRMS. We will demonstrate different types of iRMS, ranging from multilayered systems to particles and vertical systems, as well. An overview of the iRMS types used in this study can be found in Figure 1. It will be shown that the multilayered iRMS particularly the physical vapor deposited (PVD-iRMS), can be used for highly efficient and reliable wafer bonding. Therefore, we have bonded different wafer types and materials at room-temperature. We have shown, that solder layers as well as surface pre-treatment is not needed for bonding anymore. In addition to that we have bonded and characterized different types of demonstrators. Figure 2 shows a bonded MEMS pressure sensor onto a ceramic substrate. In addition to that, we will demonstrate that the electro-chemical deposition (ECD), such as the water based electrolytes (WB-iRMS) and ionic liquids (ioLi-iRMS) are new innovative and more cost efficient deposition techniques for multilayered iRMS. Herein, we developed single bath electrolytes, where two educts are in one electrolyte. With a defined current/density signal educts A and B were deposited, respectively. Figure 3 shows these deposition results using WB-electrolytes. Via SEM- as well as EDX-analysis we have investigated that depending on the applied potential different surface morphologies and educt A/B ratios could be achieved, respectively. Based on these results we have successfully deposited individual layers with a high purity and we were able to stack A and B layer as WB-iRMS. Contrary to the state-of-the-art multilayer approach we will show new iRMS deposition methods. These two are iRMS deposited via aerosol jet (AJ-iRMS) and vertically arranged iRMS (V-iRMS). Figure 4 shows first results for V-iRMS. It has been demonstrated that different geometries are suitable for V-iRMS (such as meander structures, cf. Figure 4a). In addition to that nano pattering with high aspect ratios (Figure 4b) as well as the deposition of educt B inside the geometries was possible (Figure 4c). Furthermore, we will show basic and boundary process conditions for the deposition of AJ-iRMS and V-iRMS.

Via Superfill with Time Pulse Plating in a Dual Couple Redox System

As fine line spacing (FLS) and blind micro vias (BMV) in substrate manufacturing progressively trend towards lower pitch, finer lines and high aspect ratios, electrodeposition of copper has become more challenging in the microelectronic packaging industry. Plating processes in substrate manufacturing necessitate high current densities to meet throughput concerns resulting in a high copper depletion gradient at the surface and via fill challenges to eliminate trapped voids. We present a manufacturable solution demonstrating a defect free, single bath electrolytic plating process by utilizing an “off-time” enabled forward-reverse pulses in a coupled Fe2+/ Fe3+redox plating solution.DC plating, modulating plating by current density variation, has been the historical norm in plating techniques employed for via fill. Time pulse plating has the added advantage in its ability to tune composition, structure and porosity by employing varied combinations of current amplitudes and time pulses.In a normal via-fill bottom up plating process, local plating rate is proportional to the local cupric ion concentration. The bottom of the via sees lower concentration than the top of the feature leading to pinch off or void formation. We investigated fluid velocity dependent convective transport inside the via. Flow velocities for both large and small vias were found to be very low for wide range of inlet flow velocities. Peclet numbers of < 10-4indicate an overwhelming dominance of diffusion impacting ion transport in the interior of the feature.When an “off time” step is incorporated into a pulsed plating recipe, it enables the relaxation of the cupric ion gradient inside the via feature by diffusion (unhindered by consumption along the vertical sidewall) while the presence of the Fe2+/ Fe3+redox couple enables preferential etching of the top of the via feature versus the bottom. This exaggerates the bottom-up fill effect and can be tuned to achieve super fill of the vias leading to a robust void free filling.We demonstrate that the incorporation of an “off-time” can result in void free fill and achieve super fill conditions in high aspect ratio via features.

Transport signatures of Majorana quantum criticality realized by dissipative resonant tunneling

We consider theoretically the transport properties of a spinless resonant electronic level coupled to strongly dissipative leads, in the regime of circuit impedance near the resistance quantum. Using the Luttinger liquid analogy, one obtains an effective Hamiltonian expressed in terms of interacting Majorana fermions, in which all environmental degrees of freedom (leads and electromagnetic modes) are encapsulated in a single fermionic bath. General transport equations for this system are then derived in terms of the Majorana $T\text{-matrix}$. A perturbative treatment of the Majorana interaction term yields the appearance of a marginal, linear dependence of the conductance on temperature when the system is tuned to its quantum critical point, in agreement with recent experimental observations. We investigate in detail the different crossovers involved in the problem, and analyze the role of the interaction terms in the transport scaling functions. In particular, we show that single barrier scaling applies when the system is slightly tuned away from its Majorana critical point, strengthening the general picture of dynamical Coulomb blockade.

Neutron reflectivity of electrodeposited thin magnetic films

We present a polarised neutron reflectivity (PNR) study of magnetic/non-magnetic (CoNiCu/Cu) thin films grown by single bath electrodeposition. We find that the composition is neither homogeneous with time, nor consistent with bulk values. Instead an initial, non-magnetic copper rich layer is formed, around 2nm thick. This layer is formed by the deposition of the dilute, but rapidly diffusing, Cu2+ ions near the electrode surface at the start of growth, before the region is depleted and the deposition becomes mass transport limited. After the region has been depleted, by growth etc., this layer does not form and thus may be prevented by growing a copper buffer layer immediately preceding the magnetic layer growth. As has been previously found, cobalt deposits anomalously compared to nickel, and even inhibits Ni deposition in thin films. The layer magnetisation and average neutron scattering length are fitted independently but both depend upon the alloy composition. Thus these parameters can be used to check for model self-consistency, increasing confidence in the derived composition.

Improved structural and optical properties of Cu2ZnSnS4 thin films via optimized potential in single bath electrodeposition

Here we report on the preparation of high quality Cu2ZnSnS4 thin films using single bath electrodeposition process via an optimized deposition potential. X-ray diffraction and Raman analysis validated the formation of kesterite phase of CZTS without any secondary phases at an optimized deposition potential of -1.4V vs. Ag/AgCl. As a signature of highly pure crystalline films of CZTS kesterite phase, we observed a characteristic Raman peak at 338cm−1 that corresponds to the vibration of sulfur atoms. Elemental analysis using energy dispersion analysis of X-rays (EDX) reveals a near ideal composition ratio of 2:1:1:4 for these films, and indicates the formation of the ideal stoichiometric compound. Furthermore, X-ray photoelectron spectroscopy analysis of the grown films illustrates an appropriate chemical composition and valence states of the constituent elements without a trace of free sulfur. Using the chrono- amperometry data and the Scharifker and Hill model we found that the nucleation mechanism for CZTS thin film is instantaneous. Optical properties demonstrated the optimum band gap of 1.5eV for kesterite CZTS film prepared from a precursor electrodeposited at -1.4V vs. Ag/AgCl. Mott-Schottky electrical measurements confirm the p-type nature of the film with a carrier concentration of 1017cm−3, a flat band potential of VFB=0.7V and space charge region width of 0.2μm.

Cold Forging with Lubricated Tools

Cold forging processes require high-capability tribological systems in order to ensure sound forming results. Due to a rising ecological awareness, alternatives to the established and reliable conversion coatings are necessary. Single bath systems like polymers and salt wax coatings with integrated lubrication appear to be the most promising approach to prevent galling. For an optimization and investigation of the tribological system a definition of the tribological loads is necessary. However, only insufficient values are available in literature. Especially, long sliding distances, which occur in multistage operations, can cause a breakdown of the lubricant. Therefore, approaches are necessary to enable long sliding distances. This paper presents the results obtained with a cold forging tribometer, the Sliding Compression Test, which reveal the high impact of remaining lubricant on the friction coefficient. Also, tests with prelubricated tools show the ability to reduce the friction and the results of investigations with rough tool surfaces are presented.

Universal features in the energetics of symmetry breaking

A symmetry breaking (SB) involves an abrupt change in the set of microstates that a system can explore. This change has unavoidable thermodynamic implications. According to Boltzmann's microscopic interpretation of entropy, a shrinkage of the set of compatible states implies a decrease of entropy, which eventually needs to be compensated by dissipation of heat and consequently requires work. Examples are the compression of a gas and the erasure of information. On the other hand, in a spontaneous SB, the available phase space volume changes without the need for work, yielding an apparent decrease of entropy. Here we show that this decrease of entropy is a key ingredient in the Szilard engine and Landauer's principle and report on a direct measurement of the entropy change along SB transitions in a Brownian particle. The SB is induced by a bistable potential created with two optical traps. The experiment confirms theoretical results based on fluctuation theorems, allows us to reproduce the Szilard engine extracting energy from a single thermal bath, and shows that the signature of a SB in the energetics is measurable, providing new methods to detect, for example, the coexistence of metastable states in macromolecules.

The effect of off-time and annealing on the magnetic behavior of CoxSn1−x alloy nanowires

CoxSn1−x alloy nanowires were ac-pulse electrodeposited into the highly ordered alumina template in the same electrolyte concentration. The effect of off-time between pulses (0, 20, 50, 100 and 200ms) on the magnetic properties and microstructure of the CoxSn1−x nanowires was investigated. Using a single electrodeposition bath, Sn content increased in the range of 3–55at.% with increasing the off-time. Improving hcp-Co (002) crystalline orientation with increasing the off-time was the main source to increase the coercivity of as-deposited alloy nanowires. Segregation of magnetic grains by Sn element led to improve the coercivity of the annealed samples. Existence of non-magnetic Sn prevented the oxidation of magnetic grains thereby saturation magnetization of the annealed samples was unchanged.

A facile energy and water-conserving process for cotton dyeing

Nowadays, all research efforts in the field of wet processing of textiles are directed towards shortening and simplification of the processing sequence. To minimise water and energy consumption, it has become necessary to combine several textile processing stages to reduce the number of operations or shorten the process time. An attempt was made to combine the pre-treatment and dyeing processes with optimal quantities of textile auxiliaries in single bath. In this process, individual stages of pre-treatment like desizing, scouring and bleaching followed by dyeing using direct dyes were carried out in a single bath without the usual intermediate washings. This process was carried out without replacing the liquor bath until the end of dyeing. An attempt was also made to dye a woven fabric at different stages, viz., grey, desizing and scouring. These efforts were made to conserve water and energy required for that particular pre-treatment process. The depth of dyeing and the colour fastness properties of all these dyed fabrics were then compared with a bleached fabric which was dyed with conventional method. The properties were at par with the conventional method. Moreover, the combined process saved 83.1 % water, 88.6 % energy (thermal) and 79.3 % time than the conventional processes. Thus, the process has been shown to be ecological, economical and energy conserving.

Conditions that bicontinuous microemulsions must fulfill to be used as template for electrodeposition of nanostructures

The conditions to obtain metal micro/nanostructures by templated electrodeposition using bicontinuous microemulsions have been proposed. For this, different microemulsions have been tested to discover, analyze and generalize the conditions that must fulfill in order to act as a template for metal electrodeposition. Bicontinuous microemulsions were selected to provide enough conductivity to permit the process at significant velocity. Using the cobalt deposition process from a single bath in the aqueous component of the microemulsion as a test, the relation between the nature of the microemulsions and the template capacity in the electrodeposition process has been deduced. Depending on the characteristics of each selected microemulsion, either continuous or nanostructured deposits (porous films or particles of 20–50nm) were obtained. The conditions for which the microemulsions act as templates in the electrodeposition are: (1) immiscibility of oil and aqueous solution components, (2) low dielectric constant of the oil to favor the non-dissolution of the electroactive species, (3) the use of a surfactant that avoids the solubilization of electroactive species. Also, the possibility of using an electrodeposition method to characterize the structure of some microemulsions has been demonstrated.

Highly Efficient Copper–Zinc–Tin–Selenide (CZTSe) Solar Cells by Electrodeposition

Highly efficient copper-zinc-tin-selenide (Cu2ZnSnSe4 ; CZTSe) thin-film solar cells are prepared via the electrodepostion technique. A metallic alloy precursor (CZT) film with a Cu-poor, Zn-rich composition is directly deposited from a single aqueous bath under a constant current, and the precursor film is converted to CZTSe by annealing under a Se atmosphere at temperatures ranging from 400 °C to 600 °C. The crystallization of CZTSe starts at 400 °C and is completed at 500 °C, while crystal growth continues at higher temperatures. Owing to compromises between enhanced crystallinity and poor physical properties, CZTSe thin films annealed at 550 °C exhibit the best and most-stable device performances, reaching up to 8.0 % active efficiency; among the highest efficiencies for CZTSe thin-film solar cells prepared by electrodeposition. Further analysis of the electronic properties and a comparison with another state-of-the-art device prepared from a hydrazine-based solution, suggests that the conversion efficiency can be further improved by optimizing parameters such as film thickness, antireflection coating, MoSe2 formation, and p-n junction properties.

Composition and crystallinity in electrochemically deposited magnetostrictive galfenol (FeGa)

Here, we report the first measurements of magnetostriction as a function of composition for electrodeposited iron-gallium alloys, also known as galfenol. Galfenol is an exciting material due to its large magnetostriction constant (up to 400 ppm) and robust mechanical properties. A wide range of sensors, actuators, and other transducers can be fabricated by taking advantage of galfenol's unique mix of magnetic and mechanical properties. Electrodeposition allows galfenol to be easily integrated into a variety of applications, such as toque sensors with conformal, monolithic active layers. In this work, we examine the underlying factors that influence magnetostriction in electrodeposited galfenol, including crystallinity and composition. Here, we have controlled the film composition, as measured by energy dispersive x-ray spectroscopy, over the range of 5–25% gallium using a single plating bath by varying deposition parameters. This composition range corresponds to the region of largest expected magnetostriction for iron gallium alloys. However, our measured magnetostriction values were significantly lower than the values for single crystal galfenol from literature. The electrodeposited films in this work appeared polycrystalline when measured using x-ray diffraction. When the texture of the film is taken into account, the magnetostriction results closely matched the predicted values. These results show that it is possible to achieve magnetostrictive galfenol thin films over a wide range of compositions using electrodeposition.

Electrofabrication of multilayer Fe–Ni alloy coatings for better corrosion protection

Electrofabrication of multilayer Fe–Ni alloy coatings were accomplished successfully on mild steel and their corrosion behaviors were studied. Multilayer comprised of alternatively formed ‘nano-size’ layers of Fe–Ni alloy of different composition have been produced from a single bath having Fe2+and Ni2+ ions using modulated (i.e. periodic pulse control) current density (cd). The deposition conditions were optimized for both composition and thickness of individual layers for best performance of the coatings against corrosion. The deposits were analyzed using scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), Hardness Tester, electrochemical AC and DC methods respectively. The multi layered deposits showed better corrosion resistances compared to the monolayer Fe–Ni (CR = 3.77 mm year−1) coating deposited using DC from the same bath; the maximum corrosion resistance being shown by the coating having 300 layers, deposited at cyclic cathodic current densities of 2.0 and 4.0 A dm−2 (CR = 0.03 mm year−1). Drastic improvement in the corrosion performance of multilayer coatings were explained in the light of changed kinetics of mass transfer at cathode and increased surface area due to modulation and layering.

CHARACTERIZATION OF NANOCRYSTALLINE NICKEL–COBALT ALLOYS SYNTHESIZED BY DIRECT AND PULSE ELECTRODEPOSITION

Nanocrystalline Ni – Co alloys are electrodeposited by direct (DC) and pulse current (PC) in an electrolyte solution which consisted of nickel sulfate, cobalt sulfate and boric acid. Electrodeposition parameters including current density, electrolyte pH and pulse times in a single electrolyte bath were changed. XRD pattern showed that the structure of the alloys depends on Co content and the synthesis parameter and changed from single phase structure (fcc) to dual phase structure (fcc + hcp). The Co content in the deposited alloys declined from 70 at.% to 50 at.% by increasing in direct current from 70 mA/cm2 to 115 mA/cm2 and also decreased from 75 at.% to 33 at.% with decrease in pH values from 4 to 2. By applying PC the Co content changed from 76 at.% to 41 at.%. Magnetic properties measurements showed the saturation magnetization (Ms) increased with increasing the Co content. There was no significant effect on coercivity values (Hc) with change in Co content and about 40 Oe was obtained for all samples. The grain size of deposited alloys obtained between 24–58 nm and 15–21 nm by applying DC and PC, respectively.

The effect of magnetic layer thickness on magnetic properties of Fe/Cu multilayer nanowires

Fe/Cu multilayer nanowires were ac-pulse electrodeposited into the anodic aluminum oxide templates prepared by a two-step mild anodization technique. Transmission electron microscopy images showed the distinct layers with a relatively high contrast. A highly pure layer (∼99%) was achieved by tuning the proper ions ratio and optimizing the off-time between pulses of each layer in the single electrodeposition bath. Fe/Cu multilayer nanowires with 38 nm diameter were obtained. The effect of reducing the Fe layer thickness on the magnetic properties of Fe/Cu multilayer nanowires was investigated. It was seen that reducing the Fe layer thickness, thereby variation of rode- to disc-like multilayer nanowires, caused to rotate the magnetic easy axis from parallel to perpendicular to the wires axis.

Analysis of the impact of a single artificial carbonic acid water bath on hemodynamic parameters in patients with hypertension

AbstractAim of the study. The aim of this study was to investigate the effect of a single artificial carbonic acid water bath on hemodynamic parameters in patients with hypertension.Material and methods. Hypertensive patients (n = 33) were measured blood pressure and heart rate before the bath and during the last minute of treatment. Additionally calculated: stroke volume (SV), cardiac output (Q), double product (RPP). The mineral water used in the therapeutic bath was artificially enriched with carbon dioxide (1000 mg/dmResults. HR decreased by 7.6 bpm (p = 0.000001), systolic blood pressure by 9.2 mm Hg (p = 0.000001), diastolic blood pressure by 7.2 mm Hg (p = 0.000001), RPP by 1970.7 (p = 0.000001), SV increased by 3.3 ml (p = 0.00004), and Q did not change and in the both measurements was 3.7 l/min.Conclusions. During the single carbonic acid bath, a decrease in blood pressure, heart rate and double product was observed. Stroke volume has increased, while there was no effect on cardiac output.

Selective formation of biphasic thin films of metal–organic frameworks by potential-controlled cathodic electrodeposition

Cathodic electrodeposition lends itself to the formation of biphasic metal–organic framework thin films at room temperature from single deposition baths using potential bias as the main user input. Depending on the applied potential, we selectively deposit two different phases as either bulk mixtures or bilayer films.