Barrier Material Research Articles

Metastable body-centered cubic CoMnFe alloy films with perpendicular magnetic anisotropy for spintronics memory

ABSTRACT A body-centered cubic (bcc) FeCo(B) is a current standard magnetic material for perpendicular magnetic tunnel junctions (p-MTJs) showing both large tunnel magnetoresistance (TMR) and high interfacial perpendicular magnetic anisotropy (PMA) when MgO is utilized as a barrier material of p-MTJs. Since the p-MTJ is a key device of current spintronics memory, i.e. spin-transfer-torque magnetoresistive random access memory (STT-MRAM), it attracts attention for further advance to explore new magnetic materials showing both large PMA as well as TMR. However, there have been no such materials other than FeCo(B)/MgO. Here, we report, for the first time, PMA in metastable bcc Co based alloy, i.e. bcc CoMnFe thin films which are known to exhibit large TMR effect when used for electrodes of MTJs with the MgO barrier. The largest intrinsic PMA’s were about 0.6 and 0.8 MJ/m3 in a few nm thick CoMnFe alloy film and multilayer film, respectively. Our ab-initio calculation suggested that PMA originates from tetragonal strain and the value exceeds 1 MJ/m3 with optimizing strain and alloys composition. The simulation of the thermal stability factor indicates that the magnetic properties obtained satisfy the requirement of the data retention performance of X-1X nm STT-MRAM. The large PMA and high TMR effect in bcc CoMnFe/MgO, which were rarely observed in materials other than FeCo(B)/MgO, indicate that bcc CoMnFe/MgO is one of the potential candidates of the materials for X - 1X nm STT-MRAM.

Diffusion Behavior of Organic Solvents in Graphene Oxide/Nano Silica Hybrid Natural Rubber Latex Nanocomposite: Experimental and Theoretical Approach

AbstractThis study explores the impact of a graphene oxide (GO)/nano silica (NS) hybrid (GO/NS) filler on the diffusion characteristics of natural rubber (NR) composites when exposed to toluene, xylene, and hexane solvents. The lowest solvent uptake is observed for NR GO/NS 3 (3 phr), which is attributed to forming a robust filler network within the composite. The calculation of crosslink density using the Flory‐Rehner equation reveals significantly higher values for NR GO/NS 3, indicating good crosslinking density in the presence of the hybrid filler. Furthermore, molecular mass between crosslinks (Mc) is calculated, demonstrating a favorable fit with the Affine model. The investigation extends to theoretical modeling, where the Korsemeyer–Peppas and Peppas–Sahlin models are employed to predict solvent uptake behavior. Strikingly, the experimental values exhibit a strong alignment with the Peppas–Sahlin model. This comprehensive analysis provides valuable insights into the diffusion behavior of graphene oxide/nano silica (GO/NS) hybrid‐reinforced natural rubber latex in organic solvents, highlighting potential applications in areas such as solvent‐resistant coatings, barrier materials for chemical storage, and enhanced performance in protective gloves and seals used in harsh chemical environments.

The Scale Model Room Approach to Test the Performance of Airtight Membranes to Control Indoor Radon Levels and Radiation Exposure

Indoor radon is one of the most significant contributors to lung cancer after smoking. Mitigation strategies based on protecting buildings with radon barrier materials, combined with home ventilation or room pressurization, are regularly used. A scale model room made from a porous ignimbrite rich in radon precursors was used as an analogue to test the efficiency of fifteen airtight membranes to reduce radon levels, also in combination with room pressurization. The results of these experiments were considered together with previous ones to propose the scale model room approach as a tool for rapidly evaluating the performance of specially designed radon barrier materials, and for radiation exposure assessment. Relative reduction of indoor radon (RIR) ranges from −20 to −94%. The most effective materials were FPO membrane, single-component silane-terminated polymer membranes and synthetic resins. The presence of additives likely modified the composition and structure of some products, improving their radon barrier capacity. The introduction of room pressurization further reduced radon levels in the model room where the membranes were applied. The overpressure necessary to reach RIRs of the order of 85–90% is very low for materials that powerfully stop radon even without ventilation, but necessarily higher for poorer membranes.

Investigation and review of FGM functional gradient materials

With the advancement of modern industries and processes, numerous structures are now required to function in thermal environments, leading to a new class of composite materials known as functional gradient materials (FGMs). Initially developed as thermal barrier materials for structural applications in aerospace and fusion reactors, FGMs have gained global recognition as vital composite materials. The overall properties of FMG are unique and different from any of the individual material that forms it. There is a wide range of applications for FGM and it is expected to increase as the cost of material processing and fabrication processes are reduced by improving these processes. Their application is increasingly recognized as a highly effective method for achieving sustainable development across various industries. In this study, an an overview of resents a detailed examination of the development, features, and essential manufacturing processes of FGMs is presented, based on a review of existing literature.

Effect of salt solution concentration and cation types on the mechanical properties of bentonite as a barrier material

Effect of salt solution concentration and cation types on the mechanical properties of bentonite as a barrier material

Requirements of the Vapour Barrier in Wood-Frame Walls

This paper examines the water-vapour diffusion resistance (Z-value) of vapour versus wind barriers by determining their Z-value ratio in exterior wood-frame walls thermally insulated with six different materials to prevent mould growth. Using WUFI Pro, the water-vapour diffusion resistance requirements were determined for thermal insulation using mineral wool and biogenic materials: wood fibre, straw, flax, grass, and hemp. Hygrothermal simulations determine the minimum Z-value ratio between these materials with vapour versus wind barriers in temperate and cold climates. Wind barriers with Z-values between 1 and 8 GPa s m2/kg were used in walls with U-values of 0.15 and 0.10 W/m2 K. The indoor moisture load was defined from classes of 1 to 5 with a U-value of 0.15 W/m2 K and classes of 2 and 3 were used for a U-value of 0.10 W/m2 K. The Z-value ratio depends on the Z-values of the wind barrier and thermal insulation material, moisture load class, and U-value. The required Z-value ratio declines with an increased wind-barrier Z-value. The vapour-barrier Z-value approaches a fixed threshold for wind-barrier Z-values approaching lower values (1 GPa s m2/kg) and those approaching higher values (8 GPa s m2/kg), depending on the thermal insulation material. This parameter study examines wind barriers with a Z-value ranging between 1 and 8 GPa s m2/kg, which characterises typical wind barriers used in Denmark For the water-vapour diffusion resistance requirement of the vapour barrier, the Z-value increases for increased moisture load classes and thermally insulated walls with lower U-values. The conversion between the Z-value, the Sd-value, and the water-vapour resistance factor µ can be found in DS/EN ISO 12572:2016.

Mechanisms of Chemically Promoted Material Removal Examined for Molybdenum and Copper CMP in Weakly Alkaline Citrate-Based Slurries

Chemical mechanical planarization (CMP) of metal components is an essential step in the fabrication of integrated circuits. Metal CMP is a complex process where strategically activated (electro)chemical reactions serve to structurally weaken the surface layers of the material being processed, and the resulting overburdens are removed under low-force abrasion. Understanding the tribo-electrochemical mechanisms of this process is crucial to successfully designing the consumable materials for advanced CMP slurries that are needed for the new technology nodes. Using a model CMP system involving copper (wiring material in interconnect structures) and molybdenum (a new diffusion barrier material for copper), the present work illustrates a tribo-electroanalytical scheme for studying various mechanistic details of metal CMP. Electroanalytical probes are employed both in the absence and in the presence of surface polishing to quantify the interplay between mechanical abrasion and chemical surface modification. Weakly alkaline slurry formulations are tested with variable concentrations of silica abrasives and a complexing agent, citric acid. The results serve to examine the link between material removal and tribo-corrosion and to identify the functions of the active slurry additives in governing the rates and selectivity of material removal for CMP.

Enhancement of thermo-oxidative stability of polyimide composites by functionalized polyimide film surface modification

Polyimide (PI) resin-based composites exhibit excellent high-temperature resistance, solvent resistance, and mechanical properties, making them have broad application prospects in various fields such as aviation, aerospace, and transportation. With the continuous development of new devices, the requirements for the service temperature and service life of materials are improved, so there is an urgent need to improve the thermo-oxidative stability of polyimide composites. In this work, PI films, aluminum-coated PI film, and copper-coated PI film with low oxygen permeability were used as surface oxygen barrier materials, and surface film modified polyimide composites were prepared. The results show that, compared with the unmodified composite materials, after aging at 350°C for 400 hours, the weight loss rates of the composites modified by three kinds of surface films all increased by more than 50%, and the bending strength retention rates of the composites respectively increased by 47%, 51%, 45%, and the interlaminar shear strength retention rates respectively increased by 107%, 82%, 78%, showing excellent thermo-oxidative stability.

Deactivation mechanism of catalyst in long-period experiment of 1,1,2-TCE dehydrochlorination

ABSTRACT VDC, as an important raw material for high barrier material PVDC and lithium-ion battery binder PVDF, had an increasing demand. The catalytic dehydrochlorination of 1,1,2-TCE to generate VDC was a green process route that was expected to replace the heavily polluting sodium hydroxide saponification process in industry. There was a certain research foundation for the catalytic dehydrochlorination of 1,1,2-TCE, among which the core problem was that the catalyst was prone to deactivation. Previous studies had calculated the average molecular structure of the spent catalyst surface species when coconut shell activated carbon was used as the support. In subsequent studies, alumina support had been proven to be a better carrier for dehydrochlorination of 1,1,2-TCE, and the selected catalyst had been used in long-period laboratory experiments. The results indicated that the catalyst life had been significantly improved. In the early stage of the reaction, the activity of the catalyst decreased rapidly. In the first 20 h, the conversion of 1,1,2-TCE decreased from 49.35% to 40.36%. From 21 h to 120 h, the conversion of 1,1,2-TCE decreased from 39.96% to 36.18%, tending to stabilize. After 120 h of reaction, the catalyst was extracted and elemental analysis, FTIR, and GPC characterization were performed on the spent catalyst surface species. The average molecular formula of the carbon deposits was obtained as C96.08H50.29Cl36.53. Compared with coconut shell activated carbon support, under the action of activated alumina support, the route of catalyst carbon deposition had changed, and the sediment was more composed of polyvinylidene chloride components. Under certain conditions, sediment formed a dynamic equilibrium, which explained why the activity of the catalyst gradually stabilized. This study revealed the catalytic mechanism of active alumina supported catalyst and the pathway of carbon deposits generation, which was of great significance for improving the lifespan of improved catalyst.

Nanocellulose as Sustainable Eco-friendly Nanomaterials: Production, Characterization, and Applications

Nanocellulose is a biodegradable nanomaterial derived from lignocellulosic biomass through mechanical, chemical, or enzymatic defibrillation processes to convert wood fibers into nanofibrils. This material consists of a network of cellulosic fibrils with a wide range of diameters, offering unique properties suitable for various functional applications. Nanocellulose can act as a substrate or coating, serving as an eco-friendly alternative to synthetic plastics. Despite having good barrier properties and strong mechanical strength, nanocellulose films are still not as effective as synthetic plastics. They are used in creating barrier materials, flexible electronics, and coatings for paper products.

Evaluating the characteristics of functionally graded plate: A Review study

Functionally graded materials (FGMs) were developed as heat barrier materials for aircraft structural applications and fusion reactors. They are now being designed for broad usage as structural components in highly harsh settings. FGMs are one of the most efficient and effective materials for achieving long-term industrial development. The present article examines FGMs in general, their applications, and existing processing approaches. It also demonstrates the behavior of FGM-generated plates under five distinct conditions: buckling, bending, vibration, theories, and loadings.

Resistance to fracture of simulated immature teeth treated with intracanal medicaments and calcium silicate-based coronal barrier materials in endodontic regeneration

Resistance to fracture of simulated immature teeth treated with intracanal medicaments and calcium silicate-based coronal barrier materials in endodontic regeneration

Delamination and Evaluation of Multilayer PE/Al/PET Packaging Waste Separated Using a Hydrophobic Deep Eutectic Solvent.

This research concerns the development and implementation of ground-breaking strategies for improving the sorting, separation, and recycling of common flexible laminate packaging materials. Such packaging laminates incorporate different functional materials in order to achieve the desired mechanical performance and barrier properties. Common components include poly(ethylene) (PE), poly(propylene) (PP), and poly(ethylene terephthalate) (PET), as well as valuable barrier materials such as poly(vinyl alcohol) (PVOH) and aluminium (Al) foils. Although widely used for the protection and preservation of food produce, such packaging materials present significant challenges for established recycling infrastructure and, therefore, to our future ambitions for a circular economy. Experience from the field of ionic liquids (ILs) and deep eutectic solvents (DESs) has been leveraged to develop novel green solvent systems that delaminate multilayer packaging materials to facilitate the separation and recovery of high-purity commodity plastics and aluminium. This research focuses on the development of a hydrophobic DES and the application of a Design of Experiments (DoE) methodology to investigate the effects of process parameters on the delamination of PE/Al/PET laminate packaging films. Key variables including temperature, time, loading, flake size, and perforations were assessed at laboratory scale using a 1 L filter reactor vessel. The results demonstrate that efficient separation of PE, Al, and PET can be achieved with high yields for material and solvent recovery. Recovered plastic films were subsequently characterised via Fourier-transform infra-red (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) to qualify the quality of plastics for reuse.

Evaluating lead-free alternatives for radiation shielding in diagnostic radiology: a case study from a tertiary general hospital in Korea.

With the continued increase in the number of pieces of diagnostic medical radiography equipment being used, radiation shielding in radiology departments is becoming increasingly important. Lead is the most commonly used material for radiation protection; however, there are numerous disadvantages associated with the use of lead, including environmental hazards and harm to the human body. Alternative shielding materials that can be used as replacements include barium sulfate, tungsten, or bismuth. Among alternative materials, barium sulfate appears to be the most cost-effective and easiest to process. In the present study, before constructing shielding barriers, a barrier thickness program for lead-free barrier materials based on National Council on Radiation Protection and Measurements (NCRP) Report No. 147 was used to determine the appropriate barrier thickness. The required thickness for lead-free boards for each type of diagnostic radiography room was calculated based on a tertiary general hospital in the Republic of Korea.

Effect of Newer Intraorifice Barriers on the Fracture Resistance of Endodontically Treated Teeth: An In Vitro Study.

This study aimed to assess and compare the fracture resistance of endodontically treated teeth using three new intraorifice barrier materials. A total of 60 extracted human mandibular premolars having single roots were decoronated to 14 mm length, prepared up to rotary F3 ProTaper Gold files, and sealed with gutta-percha and AH Plus sealer. Specimens were divided into one control and three experimental groups (n = 15): Group 1, control; Group 2, Biodentine (Septodont, Saint Maur des Fosses, France); Group 3, resin-modified glass ionomer cement (RMGIC, GC Gold Label 2 LC, GC Corporation, Tokyo, Japan); and Group 4, flowable nanohybrid composite (G-aenial Universal Flo, GC Corporation, Tokyo, Japan). A 3 mm coronal gutta-percha was replaced with respective intraorifice barrier materials in the experimental groups, and the fracture resistance of all the groups was tested using the universal testing machine. One-way analysis of variance andTukey's post-hoc test were conducted. The experimental groups showed higher mean load values than the control group. The flowable composite showed the highest mean loads followed by Biodentine and RMGIC. The mean fracture resistance of flowable nanohybrid composite and Biodentine was significantly higher than that of the control. No statistically significant differencewas observed among the other groups. The flowable nanohybrid composite and Biodentine significantly improved resistance to fracture of endodontically treated teeth when compared to the control.

Diffusion of radioactive waste elements from underground water and leachates of phosphate waste forms in pore solution of clay materials

Using through diffusion method at room temperature, migration of RW element simulators (P, Se, Br, Mo, Cs, U) in compacted samples of clay materials of various mineral compositions was studied during porous diffusion from model solutions: underground water and leachates of phosphate waste forms having a total salt content of up to 500 mg/L. Based on the results of experiments, effective diffusion coefficients and sorption distribution coefficients of elements in barrier materials were determined. Numerical models are proposed to describe diffusion transfer of selenium, cesium and uranium depending on porosity, mineral composition of materials, and concentration of elements in pore solution. Patterns of diffusion of elements from solutions of different salt composition were revealed.

Revealing Microstructure and Enduring Properties of Settled Barite Extracted from an Offshore Well Two Decades Later: Well Abandonment and Slot Recovery

Summary Barite settling in the annulus behind the casing is an undesired yet common occurrence during the life of a well. Over time, the drilling fluid left in the annulus settles, leaving behind solidified barite that can hinder slot recovery and plug and abandonment (P&A) operations by impeding the cut and pull process. During a P&A operation, Equinor acquired settled barite samples from a North Sea well where the casing was held back by these weighting agents, introducing overpull and prolonging the cut and pull operation. A laboratory analysis program that included determination of the particle-size distribution (PSD), electrokinetic potential of particles (zeta potential), crystallography [X-ray diffraction (XRD)], chemical composition [X-ray fluorescence (XRF)], thermogravimetric analysis (TGA), and microstructure [scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and quantitative evaluation of materials by scanning electron microscopy (QEMSCAN)] was carried out on these settled barite samples to understand their properties. The results of this study provided valuable insights into the composition and characteristics of the settled material in the annulus. The solidified barite within the annular space exhibited no signs of chemical reactions. XRD analysis confirmed the barite to be the sole predominant solid in the solidified material, aligning with expectations. However, additional analytical techniques, including XRF, QEMSCAN, and EDS, detected interconnections between barite particles, primarily facilitated by iron or quartz particles. Additionally, trace amounts of calcite, iron oxide, and mixed compositions involving Si, S, Fe, Ba, O, and Cl were identified within the solidified material. SEM results indicated that the particles exhibited strong compaction characteristics but lacked cementation, retaining some porosity. Notably, the absence of bentonite or other clays was consistently observed in all analyses. This study highlights the process of solidification observed in settled barite, suggesting that factors other than chemical reactions may be responsible for this phenomenon. The potential mechanisms contributing to solidification include physical aggregation, compaction, and alterations in surface charge under downhole conditions. This enhanced understanding of the solidification process will contribute to the development of solutions for efficient casing removal and even the usage of settled barite as a barrier material.

Thermal cycling property of the novel Hf6Ta2O17/YSZ TBCs prepared by atmospheric plasma spraying technology

Hf6Ta2O17, with low thermal conductivity, high thermal expansion coefficient, and excellent fracture toughness, was a promising candidate ceramic top coat material of thermal barrier coating (TBC). A novel Hf6Ta2O17/YSZ double ceramic top coat prepared by atmospheric plasma spraying (APS) was applied to study the role of the microstructure and mechanical property on the thermal cycling property at 1200 °C. Results show that the rapid decomposition of Hf6Ta2O17 occurred during the spraying process. As the increased spraying power, more HfO2 phases were observed in the Hf6Ta2O17/YSZ TBCs. Besides, the porosity of the Hf6Ta2O17 ceramic top coat decreased with the increased spraying power, resulting in the elastic modulus of the Hf6Ta2O17 ceramic top coat enhancement. The highest cycles at 1200 °C were obtained for the Hf6Ta2O17/YSZ TBCs with the lowest elastic modulus and least HfO2 phases, and were twice as long as the cycles of the single YSZ TBCs. The chemical reaction between HfO2 and Hf6Ta2O17 might have contributed to the cracking of the Hf6Ta2O17/YSZ TBCs. This work provides a new option for the preparation and development of the ternary oxides by APS.

Effects of the SmFeN content on the electromagnetic wave absorbing properties of sandwich-structured YSZ/SmFeN/YSZ composites

In this study, the thermal barrier material Yttria Stabilized Zirconia (YSZ) and the electromagnetic wave (EMW) absorbing agent samarium iron nitrogen (SmFeN) were used to prepare a YSZ/SmFeN/YSZ sandwich-structured composite. The YSZ/SmFeN interface was prepared perpendicular to the directions of EMWs. The EMW attenuation of the composites with different SmFeN contents and their mechanisms were studied using electromagnetic parameters, impedance matching, Cole–Cole circles, and minimum reflection loss (RLmin value). Dielectric loss was the dominant mechanism behind EMW attenuation for the composites. In addition, the dipole orientation of SmFeN and the presence of phase interface induced the dielectric loss. The mechanism of dipole orientation polarization was influenced by SmFeN content; the lesser the SmFeN content in the composite, the higher the ε′ (real part of dielectric coefficient). The frequency at which ε ′ peaked shifted decreased with increasing SmFeN content. Higher dielectric losses were observed in the frequency band of 4.0–8.0 GHz. The EMW absorption rate showed that the optimum EMW absorption effect was achieved when the thickness ratio of YSZ:SmFeN:YSZ was 1:4:1 and the thickness is 3.325 mm. The corresponding RLmin was −35.3 dB and effective absorption bandwidth was 9.5 GHz (8.3–17.9 GHz).

DC and RF analysis of ScAlN/GaN/β-Ga2O3 and ScAlN/InGaN/GaN/β-Ga2O3 HEMTs on SiC substrate

Scandium aluminum nitride (ScxAl1-xN) is a promising material among group III nitrides, offering outstanding polarization properties resulting in very large carrier densities. We report the comparative analysis of Sc0.18Al0.72N/GaN/β-Ga2O3 and Sc0.18Al0.72N/InGaN/GaN/β-Ga2O3 HEMTs on Silicon carbide substrate. LG = 55 nm, Sc0.18Al0.72N/GaN/β-Ga2O3 HEMT demonstrated maximum current density (IDS) of 4.38 A/mm, very large carrier density (ns) of 2.34 × 1013 cm−2, large breakdown voltage (74 V) with low on-resistance (Ron ∼ 0.2 Ω mm), and cut-off frequency (fT)/maximum oscillation frequency (fmax) of 220/242 GHz. Introduction of a very thin 5 nm In0.1Ga0.9N layer in the channel, further improves the 2DEG (two-dimensional electron density), drain current, breakdown voltage. Furthermore, Sc0.18Al0.72N/InGaN/GaN/β-Ga2O3 heterostructure shows stable transconductance (gm) over wide gate bias. A gate voltage swing (GVS) of 7.72, IDS of 6.08 A/mm, and VBR of 105 V with Ron ∼ 0.138 recorded. These findings show the merits of scandium aluminium nitride barrier material, which enables the HEMTs for next generation radar and telecommunications.