Design of Multifunctional Nanopore Using Polyampholyte Brush with Composition Gradient

Multi-element material coating systems have received much attention for improving the mechanical performance in industry. However, they are still focused on ternary systems and seldom beyond quaternary ones. High entropy alloy (HEA) bulk material and thin films are systems that are each comprised of at least five principal metal elements in equally matched proportions, and some of them are found possessing much higher strength than traditional alloys. In this study, CrVTiNbZr high entropy alloy and nitrogen contained CrVTiNbZr(N) nitride coatings were synthesized using high ionization cathodic-arc deposition. A chromium-vanadium alloy target, a titanium-niobium alloy target and a pure zirconium target were used for the deposition. By controlling the nitrogen content and cathode current, the CrNbTiVZr(N) coating with gradient or multilayered composition control possessed different microstructures and mechanical properties. The effect of the nitrogen content on the chemical composition, microstructure and mechanical properties of the CrVTiNbZr(N) coatings was investigated. Compact columnar microstructure was obtained for the synthesized CrVTiNbZr(N) coatings. The CrVTiNbZrN coating (HEAN-N165), which was deposited with nitrogen flow rate of 165 standard cubic centimeters per minute (sccm), exhibited slightly blurred columnar and multilayered structures containing CrVN, TiNbN and ZrN. The design of multilayered CrVTiNbZrN coatings showed good adhesion strength. Improvement of adhesion strength was obtained with composition-gradient interlayers. The CrVTiNbZrN coating with nitrogen content higher than 50 at.% possessed the highest hardness (25.2 GPa) and the resistance to plastic deformation H3/E*2 (0.2 GPa) value, and therefore the lowest wear rate was obtained because of high abrasion wear resistance.

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Microstructure of Compositionally Graded PZT films Grown by Pulsed Laser Deposition

Microscopy and Microanalysis ◽

10.1017/s143192760808937x ◽

2008 ◽

Vol 14 (S3) ◽

pp. 53-56

Author(s):

S.A.S. Rodrigues ◽

A. Khodorov ◽

M. Pereira ◽

M.J.M. Gomes

Keyword(s):

Pulsed Laser Deposition ◽

Lead Zirconate Titanate ◽

Film Growth ◽

Pulsed Laser ◽

Hysteresis Loops ◽

Lead Zirconate ◽

Laser Deposition ◽

Composition Gradient ◽

Complex Structures ◽

Pzt Films

Ferroelectric films with a composition gradient have attracted much attention because of their large polarization offset present in the hysteresis loops. Lead Zirconate Titanate (PZT) films were deposited on Pt/TiO2/SiO2/Si substrates by Pulsed Laser Deposition (PLD) technique, using a Nd:YAG laser (Surelite) with a source pulse wavelength of 1064 nm and duration of 5-7 ns delivering an energy of 320 mJ per pulse and a laser fluence energy about 20 J/cm2. The film growth is performed in O2 atmosphere (0,40 mbar) while the substrate is heated at 600°C by a quartz lamp. Starting from ceramic targets based on PZT compositions and containing 5% mol. of excess of PbO to compensate the lead evaporation during heat treatment, three films with different compositions Zr/Ti 55/45, 65/35 and 92/8, and two types of complex structures were produced. These complex structures are in the case of the up-graded structure (UpG), with PZT (92/8) at the bottom, PZT (65/35) on middle and PZT (55/45) on the top, and for down-graded (DoG) one, that order is reversed.

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Controllable field-free switching of perpendicular magnetization through bulk spin-orbit torque in symmetry-broken ferromagnetic films

Nature Communications ◽

10.1038/s41467-021-22819-4 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Xuejie Xie ◽

Xiaonan Zhao ◽

Yanan Dong ◽

Xianlin Qu ◽

Kun Zheng ◽

...

Keyword(s):

Magnetic Field ◽

Domain Walls ◽

Single Layer ◽

Ferromagnetic Film ◽

Effective Field ◽

Composition Gradient ◽

Spin Orbit ◽

Interlayer Exchange Coupling ◽

Magnetization Switching ◽

Perpendicular Magnetization

AbstractProgrammable magnetic field-free manipulation of perpendicular magnetization switching is essential for the development of ultralow-power spintronic devices. However, the magnetization in a centrosymmetric single-layer ferromagnetic film cannot be switched directly by passing an electrical current in itself. Here, we demonstrate a repeatable bulk spin-orbit torque (SOT) switching of the perpendicularly magnetized CoPt alloy single-layer films by introducing a composition gradient in the thickness direction to break the inversion symmetry. Experimental results reveal that the bulk SOT-induced effective field on the domain walls leads to the domain walls motion and magnetization switching. Moreover, magnetic field-free perpendicular magnetization switching caused by SOT and its switching polarity (clockwise or counterclockwise) can be reversibly controlled in the IrMn/Co/Ru/CoPt heterojunctions based on the exchange bias and interlayer exchange coupling. This unique composition gradient approach accompanied with electrically controllable SOT magnetization switching provides a promising strategy to access energy-efficient control of memory and logic devices.

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Composition Gradient in Electrodeposition of Thin CoPt Films from the Quiescent Hexachloroplatinate Solutions

Journal of The Electrochemical Society ◽

10.1149/2.0361702jes ◽

2016 ◽

Vol 164 (2) ◽

pp. D30-D38 ◽

Cited By ~ 3

Author(s):

Oana Dragos-Pinzaru ◽

Steve Riemer ◽

Ibro Tabakovic

Keyword(s):

Composition Gradient

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Gas-phase detonation propagation in mixture composition gradients

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2011.0342 ◽

2012 ◽

Vol 370 (1960) ◽

pp. 567-596 ◽

Cited By ~ 27

Author(s):

D. A. Kessler ◽

V. N. Gamezo ◽

E. S. Oran

Keyword(s):

Activation Energy ◽

Reaction Model ◽

Single Step ◽

Mixture Composition ◽

Composition Gradient ◽

Detonation Properties ◽

High Activation ◽

Zone Structure ◽

Detonation Cell ◽

High Activation Energy

The propagation of detonations through several fuel–air mixtures with spatially varying fuel concentrations is examined numerically. The detonations propagate through two-dimensional channels, inside of which the gradient of mixture composition is oriented normal to the direction of propagation. The simulations are performed using a two-component, single-step reaction model calibrated so that one-dimensional detonation properties of model low- and high-activation-energy mixtures are similar to those observed in a typical hydrocarbon–air mixture. In the low-activation-energy mixture, the reaction zone structure is complex, consisting of curved fuel-lean and fuel-rich detonations near the line of stoichiometry that transition to decoupled shocks and turbulent deflagrations near the channel walls where the mixture is extremely fuel-lean or fuel-rich. Reactants that are not consumed by the leading detonation combine downstream and burn in a diffusion flame. Detonation cells produced by the unstable reaction front vary in size across the channel, growing larger away from the line of stoichiometry. As the size of the channel decreases relative to the size of a detonation cell, the effect of the mixture composition gradient is lessened and cells of similar sizes form. In the high-activation-energy mixture, detonations propagate more slowly as the magnitude of the mixture composition gradient is increased and can be quenched in a large enough gradient.

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Thermal stability of nickel-cobalt multilayer silicide

MRS Proceedings ◽

10.1557/proc-0891-ee07-29 ◽

2005 ◽

Vol 891 ◽

Author(s):

Kil Jin Han ◽

Yu Jung Cho ◽

Soon Young Oh ◽

Yong Jin Kim ◽

Won Jae Lee ◽

...

Keyword(s):

Thermal Stability ◽

High Temperature ◽

Depth Profile ◽

Ternary Phase ◽

Nickel Silicide ◽

Composition Gradient ◽

Cobalt Silicide ◽

Nickel Cobalt ◽

Thermal Stability Of ◽

Xps Depth Profile

ABSTRACTIn this study, we have investigated the structure of nickel-cobalt silicide to understand its behavior at high temperature. Nickel-cobalt silicide was formed after two-step RTP at 500°C and 700°C respectively. We could observe by TEM that nickel-cobalt silicide consists of a structure which seems to be a Ni-Co-Si ternary phase. No nickel silicide phases and cobalt silicide phases were detected in nickel-cobalt silicide by XRD. From XPS depth profile, we could confirm that there is a cobalt composition gradient along the silicide.

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