Mixed Alloy Research Articles

Theoretical aspects of structure, electronic, optical and elastic properties of Ca(1-x)CxSe mixed alloys in binary and ternary phases

The structural, optoelectronic, and elastic properties of Carbon doped Calcium Selenide binary and ternary semiconductor alloys with the general form of Ca(1-x)CxSe, 0 ≤ x ≤ 1 in B1 and B3 phases have been scrutinized adopting augmented plane wave plus local orbital methods within density functional theory applying different approximations like the Local density approximation (LDA), Wu-Cohen-Generalized Gradients Approximation (WC-GGA) and modified Becke-Johnson (mBJ). Structural properties summarize the crystal structure, relevant atomic positions, lattice constant, Bulk modulus B0, minimum energy E0, and minimum volume V0. Elastic constants confirm the structure stability of the B1 and B3 phases. The band gap was modified from a wider for appropriate optoelectronic devices application to narrow that enhanced the range of applicability of these binary and ternary semiconductor compounds for optoelectronic device applications. Whereas optical properties which include the study of zero frequency limit of static dielectric constant ε0(ω) with its real and imaginary parts, static refractive index n(0), optical reflectivity R(ω), optical absorption coefficient α(ω), optical conductivity σ(ω), and loss function L(ω) studied comprehensively to get real electrical and optical properties of these materials and give semiconductor market best alternative candidate which shows its effectiveness in the visible, ultraviolet and infrared region of the electromagnetic spectrum. Obtained results compared together and with the available experimental along with theoretical work on these binary and ternary Carbon-doped Alkaline earth Selenide.

Optical and thermoplasmonic properties of core (AuxAg1- x)- shell (Au) nanostructures

The optical and thermoplasmonic properties of bimetallic nanoparticles (NPs) offer a wide range of possibilities for designing functional materials and innovative nanotechnological devices. Their exploration is generating increasing interest in experimental and theoretical scientific research. The combination of noble metals such as gold (Au) and silver (Ag) within the same nanostructure, in the form of an alloy or core/shell arrangement, presents several advantages and potential applications. In this paper, the finite element method (FEM) is used to study the optical response and nanoscale heat generation capability of bimetallic core/shell nanospheres composed of a mixed alloy (AuxAg1−x)-core and an Au-shell. First, we studied the surface plasmon resonance (SPR) properties by generating absorption spectra. Our results show that the position and amplitude of the SPR peak of these nanospheres are strongly influenced by the fractions of Au and Ag metals composing the core, as well as by the Au-shell thickness. In particular, the SPR-peak position can be adjusted between 535nm and 1085nm depending on the composition and structure of these NPs. Secondly, we studied the ability of these NPs to convert absorbed light into heat when exposed to either a continuous wave (cw) laser or a femtosecond pulsed (fs-pulsed) laser. The results demonstrate the ability to control the temperature generated by these NPs based on the core composition, Au-shell thickness, illumination intensity, and the type of illumination (cw or fs-pulsed). In particular, under fs-pulsed illumination, the internal temperature of the NPs is significantly higher than under cw illumination. These findings are crucial for the use of these alloy-core and Au-shell nanoparticles in various thermoplasmonic applications.

Mechanism of Fe-rich phase supercooling induced by CDS process to regulating microstructure and strengthen properties of Al-Si-Fe alloy

Excessive iron in aluminum alloys forms compounds that weaken their strength and workability. Therefore, controlling the morphology of the Fe-rich phase is vital for developing strong, high-quality aluminum alloys. This research explores the controlled diffusion solidification (CDS) process, an innovative approach designed to optimize the morphology and distribution of the Fe-rich phase, thereby enhancing the alloy properties beyond what conventional methods can achieve. Specifically, the CDS process uniquely modifies the solidification behavior of the alloy, suppressing the growth of the primary Fe-rich phase and enhancing the overall properties. This demonstrating the ability of process to refine microstructural characteristics effectively. The experimental results confirm the presence of primary Si and Al3Fe in the CDS process samples. Consequently, the nucleation of Al3Fe in the precursor alloy leads to the concentration of Fe solutes reduce, impeding the nucleation and growth of the primary Fe-rich phase during the subsequent solidification process. The key factors are temperature difference between two mixed alloy and mass ratio of precursor alloys. The mass ratio influences the precipitation sequence of the precursor alloys, while the difference of temperature and concentration induces the undercooling necessary for nucleation. The study reveals that an optimal mass ratio of 4:1 in the CDS process achieves the best mechanical properties with a 73.78 % increase in ultimate tensile strength (UTS) and a 107.77 % increase in elongation (UL) compared to conventional casting. The findings provide a theoretical basis for controlling the Fe-rich phase evolution, significantly augmenting the performance of Al-Si-Fe alloys. The findings not only enhancing the optimizing fundamental reactions in the CDS process for other alloy systems but also enriching the broader field of materials science.

Progress on the Development of Boron Subphthalocyanines (BsubPcs) and Subnaphthalocyanines (BsubNcs) Including Hybrids and Their Sustainability

Our group focuses on molecular design, synthetic methods and in-depth characterization of boron subphthalocyanines (BsubPcs) and subnaphthalocyanines (BsubNcs)[1] to apply them to organic electronics.[2] BsubPcs, BsubNcs and their hybrids called Bsub(Pc3-p-Ncp) are macrocycles with central boron atom and are p-conjugated macrocycles. Our focal point balances between the basic and applied chemistry, chemical engineering and their in-depth physical properties (electrochemistry included). Once materials are developed, we merge them into organic electronics for application into organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs)/organic solar cells (OSCs).For this presentation, all points above will be factored in and I will focus on our progress on the development of hybrids, and mixed alloys and none mixed alloys of BsubNcs,.Regarding hybrids, they are a mixture of BsubPcs and BsubNcs, we named as X-RnBsub(Pc3-p-Ncp) – ‘p’ being the numbers of the substitutions; they were formed via reaction of BCl3 and a statistical distribution of phthalonitrile and 2,3-dicyanonaphthalene; X the axial substituent, Rn the number of peripheral substitutions, Pcp the number of 6 p-conjugated bonds, Ncp the number of 10 p-conjugated bonds (Figure).[3] We found that X-RnBsub(Pc1-Nc2) have low photostability, therefore, we developed a ‘statistical’ synthetic methodology to target X-RnBsub(Pc2-Nc1)s, and therefore could be purified to enable physical characterization. Their absorption spectra are as wide if BsubPc+BsubNc was mixed together, therefore, has potential to harvest a larger scope of photons for OPVs or to achieved FRET transfer from a host to emit via OLED. We also confirmed their electrochemical oxidation and reduction stability and their photoluminescence.More recently, we developed a new methodology called ‘steric hinderance’ to have even a higher yield of the X-RnBsub(Pc3-p-Ncp) hybrids, and the achievement was also based on computational modelling. I will also outline this approach.In the past as we have shown that BsubNcs end up being a mixed alloyed composition with random bay-position halogenation that is formed during the reaction of BCl3 with 2,3-dicyanonaphthalene at temperature.[4] The random bay-position halogenation has been shown to be impactful in a positive way within OPV devices, negative within OLED devices and also has electrochemical variations. Ongoing, given it is random halogenation, and some of the positive outcomes, this justifies considering additional mixed alloyed compositions.We have recently been able to develop a separation method for the mixed alloyed BsubNc compositions and acquired data to show the impact of the percentage/number of bay-position halogens, chlorine and bromine included, on the electrochemical potentials and the photoluminescence.[5] We have also applied a computational model to look at the relative impact of the random bay-position halogenation on the electronics.[6] We have found that the frequency of halogenation has a larger impact on the predicted HOMO/LUMO energy levels than does the random halogen positioning around the bay-positions of the BsubNcs. As this computational data is therefore comparable to the acquired electrochemical data.I will also present a new synthetic methodology to avoid the random bay-position halogenation of the associated BsubNcs. We also have recently within these semesters developed alternative chemistry to more tune the mixed alloys of the BsubNcs. This will also be a part of the presentation.We have also recently developed an AI-ML method to further accelerate the BsubNc development. The focal point of this approach was to have bay-position substitutions to then not have any random bay-position halogenation of the BsubNcs. So, these current and upcoming outcomes will also be a part of the presentations.For this presentation, I will also be outlining the sustainability of these great macrocyclic compounds. Claessens, C. G.; et al, Subphthalocyanines, Subporphyrazines, and Subporphyrins: Singular Nonplanar Aromatic Systems. Chem. Rev. 2014, 114 (4), 2192-2277.Morse, G. E.; et al, Boron Subphthalocyanines as Organic Electronic Materials. ACS Appl. Mater. & Interfaces 2012, 4 (10), 5055-5068.Farac, N.F.; et al, Cs-Symmetric, Peripherally Fluorinated Boron Subphthalocyanine–Subnaphthalocyanine Hybrids: Shedding New Light on Their Fundamental Photophysical Properties and Their Functionality as Optoelectronic Materials. J. Phys. Chem. C 2023, 127 (1), 702–727.Dang, J. D.; et al, The mixed alloyed chemical composition of chloro-(chloro)n-boron subnaphthalocyanines dictates their physical properties and performance in organic photovoltaic devices. J Mater. Chem. A 2016, 4 (24), 9566-9577.Holst, D.P.; et al, Enhanced analytical and physical characterization of mixtures of random bay-position chlorinated boron subnaphthalocyanines enabled by an established partial separation method (a part 2). New J. Chem. 2021, 45, 21082-21091.Holst, D.P.; et al, Updated Calibrated Model for the Prediction of Molecular Frontier Orbital Energies and Its Application to Boron Subphthalocyanines. J. Chem. Inf. Model. 2022, 62 (4), 829–840. Figure 1

More resource efficient recycling of copper and copper alloys by using X-ray fluorescence sorting systems: An investigation on the metallic fraction of mixed foundry residues.

According to the state of the art, most of the mixed copper and copper alloy scrap and residues are processed in a copper smelter. Despite the environmental and economic advantages relative to primary production, the recycling of copper and its alloying elements (zinc, tin, lead, nickel, etc.) requires significantly more energy and cost than remelting unmixed or pure scrap fractions such as separate collected material or production scrap. To date, however, less attention has been given to the mechanical purification of mixed scrap. Therefore, sorting by alloy-specific components (SBASC) using an industrial X-ray fluorescence (XRF) sorting system was tested on the coarse metallic fraction (10-32 mm) of mixed foundry residues. The findings show that XRF-SBASC can recover higher-grade copper concentrates (reaching 98.3% Cu), leaded brass and complex alloys, such as aluminium bronze and red brass with high purities, for the use in the production of new materials. XRF-SBASC can therefore contribute to a more resource efficient metal recycling, mainly by reducing the energy consumption and loss levels in copper metallurgy.

Strengthening of duplex Mg–9Li–3Al–2Zn–1Sn alloy by solid solution and mixed rolling-induced second phase transition

This work investigated the microstructure and mechanical properties of Mg–9Li–3Al–2Zn–1Sn alloy after solid solution and mixed rolling (hot rolling followed by room-temperature rolling). The research results reveal that after solid solution, AlLi and Mg2LiZn3 phases disappear, while MgLi2Al phases partially disappear. The hardness of the β-Li phase is much higher than that α-Mg phase, and the strength of the alloy is significantly increased while the elongation decreases to 1.4 %. Low plasticity is mainly due to lattice distortion and the presence of coarse Sn-rich phases. After mixed rolling, a large quantity of second phase precipitation in the alloy plays a role of second phase strengthening. The Mg17Al12 phases are observed to precipitate inside the α-Mg phase, and the AlLi phases containing MgLi2Al and Mg2LiZn3 nanophases inside are found at the β-Li phase and α-Mg/β-Li phase interface. The YS and UTS of the mixed rolled alloy reach 253 MPa and 273 MPa, respectively, with an improved EL of 18.4 %.

Ordered phases in ternary wurtzite group-III nitrides: A first-principles study

A first-principles-based lattice model is applied to investigate the ordered phases of mixed group-III nitride ternary alloys. The model surveys the atomistic configurations with the lowest formation enthalpy for a wide range of compositions. We found novel ordered phases in wurtzite structures having specific compositions of three- and four-sevenths molar fractions of group-III cations. The configurations of group–III atoms on cation sites in those phases consist of a characteristic fragment of the ordered phases of one-third and one-half ordered phases that were previously reported. The simulation results indicate that group-III cations in ternary nitrides follow spatial positioning “atomistic distancing rules” that can be described by the pairwise interaction energy of group-III cations to realize the stabilities of the ordered structures. To minimize the formation enthalpy of a mixed crystal, the minor B, Al, Ga, and In atoms on cation sites remain neither too close to nor too distant from each other, allowing those ordered phases to be realized.

First-principles study on structural, electronic, and optical properties of mixed alloys of Cs2Ag(SbxBi1−x)Br6 double perovskites for optoelectronic applications

Halide perovskites have attracted promising capabilities of solar cells and light-emitting diode applications due to their high stability and optoelectronics performance. In this work, the effect of chemical substitution on the structural, electronics, and optical properties of mixed alloy Cs2Ag(SbxBi1-x)Br6 perovskites (when x is a mixing ratio varying from 0.0 to 1.0) was explored by using the virtual crystal approximation within the first-principle framework based on DFT-GGA, GGA-TB09, RPA, and BSE. Calculation results reveal that the lattice constant increases linearly as a function of the mixing ratio of a(x) = 11.246–0.0012x Å. These results satisfied the Vegard’s law as well as the reliability of virtual crystal approximation. The band structure calculated with and without the spin–orbit coupling was compared. Band gap of the mixed alloys are lower than that of pure Sb or pure Bi compounds. The band gap increases as a quadratic function of Eg = 2.07 – 0.279x – 0.121x2 eV. The smaller band gap of the mixed alloy results from the energy mismatch between Sb and Bb s and p orbitals. Calculations from DFT-TB09 are in good agreement with experimental results. Blue-shifted absorption spectra to the ultraviolet region were found when the Sb content increased. A linear increase of the static dielectric constant was found when the Sb content increased as a function of εs(x) = 2.849 + 0.266x. BSE@PBEsol calculations are consistent with experimental profiles. Calculation results indicate that the mixed alloy Cs2Ag(SbxBi1-x)Br6 can be tuned regarding its electronic and optical properties.

Exotic Topological Magnetic States in Thin Co/Pd Ferromagnetic Films

AbstractThin ferromagnet/heavy metal multilayer films are considered as prospective media for a magnetic recording and Co/Pd films are a good example of such materials. In this work, the magnetic properties and micromagnetic structure of Co/Pd multilayer films are studied with different bilayer thicknesses ([Co(0.3 × t nm)/Pd(0.5 × t nm)]10), but with the same ratio Co versus Pd. Transmission electron microscope and X‐ray diffraction studies allow authors to suppose that the investigated films are highly mixed alloys. Magnetic force microscopy and Lorentz transmission electron microscopy showed the presence of various micromagnetic features in the films. Along with skyrmions that are well‐known magnetic topological artifacts some new features are revealed, which are interpreted as 360° domain walls, skyrmioniums and the combination of the above two. It is found that the type and density of micromagnetic features strongly depend on the bilayer thickness parameter (t). The effect is associated with the peculiarities of interfacial magnetic interactions in the samples with highly mixed interfaces. The tooling coefficient represents a useful tool of the electron beam evaporation technique enabling wide manipulation of micromagnetic particles, in particular, skyrmioniums that are currently considered a prospective media for current driven magnetic recording.

Effect of progressive substitution of spin-3/2 by spin-7/2 on the magnetocaloric properties of a mixed spin binary alloy system: A Monte Carlo study

Using Monte Carlo simulation the concentration dependency of the cooling exponent (n) of a binary alloy AxB1-x mixed spin system (7/2, 3/2) was studied rigorously. For low magnetic field (h) the entropy change (ΔS), excellently follows the relation ΔS∝hn. The exponent n hardly changes with x within the region 0.5 < x < 0.75. But for further increment of x > 0.75, n sharply drops down. The exponent n is strongly affected by the exchange interaction energy (ε). Due to the decrement of the antiferromagnetic interactions n value rapidly decreases. For the increment of x or the number of A(spin-7/2) atom the magnetization M as well as the magnetic entropy change ΔS increases. The phase transition temperature (i.e. Curie temperature) tC linearly decreases for the increase of x.

Control of Self-Assembly and Elemental Mixing of AuNi Bimetallic Nanoparticles via Solid-State and Liquid-State Dewetting of Metal Thin Films

Immiscible Au-Ni alloy thin films undergo phase separation and dewetting because of thermodynamic and morphological instability at elevated temperatures below the miscibility gap. We report the formation and assembly of bimetallic nanoparticles (BNPs) on topographic Si templates. An ordered array of inverted pyramidal pits were produced via solid-state and liquid-state dewetting of a 12-nm-thick Au-Ni thin film by respectively using thermal annealing and laser irradiation. Upon direct thermal annealing at 600 and 800 &lt;sup&gt;o&lt;/sup&gt;C, the thin film on the templates self-assembled into an ordered array of BNPs composed of Au-rich and Ni-rich sub-clusters in pits. But the relative proportions of the two sub-clusters varied with annealing temperature due to the additional formation of smaller Ni-rich NPs that were scattered around the BNPs. Laser irradiation of the film, in contrast, formed an ordered array of fully mixed alloy NPs on the template and left no other residues on the surface. Subsequent thermal annealing induced the elements within the NPs to segregate, resulting in Au-rich and Ni-rich sub-clusters. In brief, the combination of solid-state and liquidstate dewetting processes on a topographic template not only enabled the 2-dimesional self-assembly of BNPs but also allowed control of the mixing of alloying elements within the BNPs. These results offer insights into the tailored fabrication of BNPs, which have potential applications in bio-functional catalysts, and plasmonic and chemical sensors.

The stability of CsPb(BrxCl1-x)3 all-inorganic mixed halide perovskites.

The use of mixed halide perovskites in the preparation of blue light-emitting diodes (LEDs) is considered to be the most effective and direct approach. However, the introduction of chlorine (Cl) element might raise stability issues in the system and lead to low efficiency, thereby impeding the development of deep blue light-emitting diodes with high efficiency and stability. Determining the alloy concentration and the atomic distribution of bromine-chlorine (Br-Cl) mixed systems is essential for further application of deep blue light-emitting diodes. In this work, we have systematically investigated the stability of bromine-chlorine (Br-Cl) mixed alloy systems in various substitution configurations using high-throughput theoretical calculations. Based on this, we have examined the relationship between configuration stability and three aspects: the type of octahedra, the orientation of the octahedra and the Pb-X-Pb distortion angle in the configuration.

Hollow TiO2 Supports for Enhanced Acidic Oxygen Evolution Activity

The usage of scarce and expensive iridium as a catalyst for the acidic oxygen evolution reaction (OER) represents a significant barrier to up-scaling the deployment of proton exchange membrane water electrolysers (PEM-WEs). Accordingly, strategies such as nanostructuring catalysts to increase the electrochemical surface area (e.g. nanoparticles, single-atom catalysts, nanoclusters) as well as investigating mixed metal alloys and oxides (e.g. perovskites, pyrochlores) have been developed with promising half-cell performances. One further approach that has recently gained attention is the deployment of catalyst-supports whereby a high surface area support is used to scaffold the dispersed iridium catalyst.1 Analogous to the selection of a catalyst, the catalyst support must withstand the highly corrosive and oxidising conditions of a PEM-WE anode. Thus, metal oxides such as titanium dioxide are commonly deployed as catalyst-supports for acidic OER. The catalyst-support moiety must also be sufficiently conductive when integrated into the PEM-WE catalyst layers. Otherwise, the cell voltages required to generate sufficient activity will render the device impractical. Accordingly, strategies such as doping, or the addition of conductive layers between the catalyst and support have been investigated.2 In this study we investigate a unique support morphology that affords promising OER activity and stability in acidic electrolyte with high iridium mass activities. Specifically, we deploy a hollow TiO2 catalyst support,3 coated with a Au/Pd interlayer to provide electrical conductivity. The OER activity and stability is initially screened in a rotating disk electrode (RDE) configuration as a function of thermal treatments (reducing vs oxidising) as well as with at various Au/Pd (1 – 5 wt%) and Ir loadings (35 – 50 wt%). Our highest performing catalyst have a mass activity of around 480 A/gIr at 1.60 V vs RHE. The catalysts are subsequently investigated in a membrane electrode assembly (MEA) and subject to 10k accelerated stress test stability measurements. To understand the role of the support morphology, Au/Pd interlayer and iridium loadings on electrochemical performance, we also characterise the synthesised catalysts by (scanning) transmission electron microscopy (STEM/TEM), X-ray diffraction (XRD), X-ray photoelectron microscopy (XPS) and electrical conductivity measurements. Collectively, we report the critical role of the Au/Pd interlayer to enable such high electrochemical performance. We also show that the hollow structure of the TiO2 support may be enhancing mass transport in the catalyst layers. References 1 A. S. Pushkarev, I. V Pushkareva and D. G. Bessarabov, Energy & Fuels, 2022, 36, 6631–6625.2 Y. N. Regmi, E. Tzanetopoulos, G. Zeng, X. Peng, D. I. Kushner, T. A. Kistler, L. A. King and N. Danilovic, ACS Catal., 2020, 10, 13125–13135.3 U. S. Jonnalagadda, X. Su and J. J. Kwan, Ultrason. Sonochem., 2021, 73, 105530.

Isotopic metal compositions of Viking and medieval tin artifacts from Poland reveal expansive trade network

The lack of historically known tin deposits in Poland requires that the source of tin metal in ancient artifacts must be derived from foreign sources. To identify these external sources in the Viking Period, a combination of Pb and Sn isotope compositions and trace element analyses on a group of tin and tin rich alloys from three settlements in Poland was conducted. The integration of the chemical techniques reveals several sources for the tin rich artifacts, where group: 1) possesses Pb isotope values that overlap the Europe array which possess the highest (+1.6 ‰) and lowest (−1.1 ‰) Sn isotope values coupled with elevated In concentrations 2) has Pb isotope values that overlap the Slovakian array which possess lower Sn isotope values (+0.1 ‰ to + 0.3 ‰) coupled with low In and Te concentrations 3) has a Pb isotope value that is radiogenic which possesses a high Sn isotope value (+1.1 ‰). Group 1 artifacts are split into two sources designated by the higher Sn isotope values from Cornwall and the lower Sn isotope values from Brittany and are found in the two coastal settlements. Group two artifacts match a Slovakian origin, while one artifact labeled in group three possesses an Anatolian source. Defining the tin rich artifact sources allows constraint of the tin sources for the mixed alloys like bronze and pewter. In this instance the tin isotope values fall within two sources defined by the tin metal artifacts, Brittany and Cornwall. The chemical approach presented here defines distal metal sources to reveal a geographically expansive interconnected tin trade network that was predominantly European, in Viking times through chemical analysis of ornaments, coins, and beads.

Hot deformation and microstructural evolution of ultrasonically fabricated as-cast Al-7.3Zn-2.2Mg-2Cu alloy

Al-7.3Zn-2.2 Mg-2Cu alloy is known for its high strength, achieved because of higher alloying concentration. However, the higher alloying concentration presents challenges during the hot deformation process. Nevertheless, hot deformation proves to be an effective method for optimizing the microstructural and mechanical properties of the material. The research presented in the study focuses on investigating the hot working response of an ultrasonically fabricated age-hardening as-cast Al-7.3Zn-2.2 Mg-2Cu alloy. The objective is to observe the attainment of a uniform and dendrite-free microstructure after a single-step hot compression. The flow stress of the deformed specimens showed a notable increase as the temperature and deformation time decreased. This increase in stress was influenced by various factors, including deformation variables and precipitate size. The accurate prediction of the hot deformation behaviour was achieved by combining the constitutive equations and a workability map. The 3-dimensional workability map revealed a gradually increasing power dissipation efficiency (PDE) from 40% to 50% with increasing strain. At the end of 50% compression, four specific optimum working regions (PDE > 40%) were identified. Through detailed microstructural analysis, the best region for hot forging of ultrasonically mixed as-cast alloy for chemical homogeneity and upgraded property is obtained in the range of (350–450 °C) & (0.1–0.001 s−1). The highest extent of recrystallization (73%) was exhibited after deformation at 450 °C-0.001 s−1. The mechanism of dynamic softening during deformation is observed due to DRV, CDRX, and PSN. The microstructural response in 0.1–0.001 s−1 and 350–450 °C indicated dynamic recrystallization, whereas strained and non-working zone was observed at low deformation temperatures (≤350 °C).

Вarothermic treatment of TixZr1-xC mixed carbides produced by MA-SHS consolidation

High density TixZr1-xC (x = 0.15; 0.24; 0.49; 0.88; 0.92) mixed alloys with a submicron structure have been successfully produced by MA-SHS under pressure followed by barothermic treatment (HIP) in a gas-static chamber. The effect of mechanical activation (MA) on the properties of reaction blends containing titanium, zirconium and carbon black powders, the formation of phase composition and microstructure, and the physical and mechanical properties of the alloys were investigated by means of X-ray diffraction (XRD) and backscattered electron mode (BSE). It was shown that the MA of the reaction blends in hexane for 40–60 min resulted in the amorphization of the metal particles and the formation of the carbide phase crystallites in them. TixZr1-xC mixed alloys produced by MA-SHS and aged at 1600 °C. The resulting TixZr1-xC mixed alloys are characterized by grain sizes of 0.1 μm, relative density of 99.2 %, microhardness (HV) of 20.9 GPa and a fracture toughness (K1c) of 12.53 MPa × m1/2. It has been shown that during ageing of the SHS alloy, the high temperature Ti0.49Zr0.51C phase completely decomposes into the daughter phases Ti0.15Zr0.85C and Ti0.92Zr0.08C. The characteristics of the alloys produced by the SPS and SHS methods are discussed.

The Effect of Ni Interlayer Formation Plating Bath on the Suppression of Oxidation of Ag-Coated Cu Flakes

To suppress Ag dewetting from around 200 oC in Ag-coated Cu (Cu@Ag) flakes, Ag and Ni-coated Cu (Cu@Ni@Ag) flakes were fabricated by successive Ni and Ag electroless plating. The Ni bath type was an important consideration to induce differences in the Ag dewetting and resultant Cu oxidation. An acid Ni bath contained succinic acid as a complexing agent and sodium hypophosphite as a reductant, and an alkaline Ni bath contained sodium citrate as a complexing agent and sodium hydroxide as a pH adjuster as well as sodium hypophosphite. A hydrazine-based Ni bath contained sodium citrate, sodium hydroxide, and hydrazine hydrate as a reductant. The acid Ni bath provided amorphous coatings with a P content of approximately 10 wt%. The Cu@Ni@Ag flakes started the Ag dewetting and Cu oxidation at 350 oC, together with the formation of the Ni3P phase. Meanwhile, the alkaline Ni bath created Ni-5 wt% P amorphous Ni coatings, which transformed into a crystalline phase after heating at 350 oC. The Ag shell was dewetted at 450 oC, which caused oxidation of the flakes. Finally, the hydrazine-based Ni bath formed crystalline coatings without P, which induced rapid mixing with the core Cu. The Ag shells on the mixed Cu-Ni alloy showed repressed dewetting behavior, and thus the dewetting and oxidation temperature was the highest, such as 500 oC. Enhancing the high oxidation resistance at approximately 300 oC will enable the use of Cu@Ni@Ag flakes as a low-cost filler material in conductive pastes, especially for long-time or high-temperature curing.

Cation replacement effect on the optical and electronic properties of Cs2Ag1-xNaxYCl6 (Y= In, Bi)

Lead-free double perovskites are environmentally friendly materials that have attracted enormous attention for their structural stability, long charge carrier lifetime, and good absorption. This work includes two double perovskites Cs2AgBiCl6, Cs2NaBiCl6 with an indirect band gap and two double perovskites Cs2AgInCl6, Cs2NaInCl6 with a direct band gap, considered to make two groups of mixed double perovskites as Cs2Ag1-xNaxBiCl6 and Cs2Ag1-xNaxInCl6 to study the effect of cation replacement on the optical and electronic properties by employing ab-initio approach. The electronic and optical properties of these materials with x = 0, 0.25, 0.50, 0.75, 1 have been studied, and a tunable bandgap from the smallest one to the widest one was found in both groups (1.46–2.85, 0.26–2.87) as they change with different x. The general trend of the band gap in each group shows that by reducing Ag contribution an increase in the band gap happens. But a minimum value at x = 0.25 in the first group, which is absent in the second group comprising In, is due to the different behavior of the half-full Bi-p orbital and full In-s orbital in the edge of the conduction band when the Na-s orbital introduced to the structure. In addition, the study of the absorption coefficient of each group shows that there is a possibility to find a better absorbent in the visible energy range in mixed alloys than the pristine ones.

Progress on Hybrids and Mixed Alloys of Boron Subphthalocyanines (BsubPc) and Boron Subnaphthalocyanines (BsubNc); Tuning the Electrochemical Properties Towards Organic Electronic Applications

Our research and development focus has been on the molecular design, synthetic methodology and in-depth characterization of boron subphthalocyanines (BsubPcs) and subnaphthalocyanines (BsubNcs) to apply them to organic electronic applications. BsubPcs, BsubNcs and their hybrids are macrocycles with a chelated central boron atom via nitrogen bonding, and is a p-conjugated macrocyclic material. Our focal point balances between the basic and applied chemistry, chemical engineering, their in-depth physical properties (electrochemistry included). We also do computational modelling. Once materials are developed, we merge them into organic electronics to function as light emitting, light absorbing and electronic conducting materials within organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs)/organic solar cells (OSCs). The basic electrochemical and photophysical properties, developing and evaluating the properties is critical to move onto such applications.For this presentation, I will focus on our progress on the development of hybrids and mixed alloys of BsubPcs and BsubNcs.Regarding hybrids, they are a mixture of BsubPcs and BsubNcs, and are formed via a reaction of a statistical distribution of phthalonitrile and 2,3-dicyanonaphthalene intermediates on reaction with BCl3; we have named them X-RnBsub(Pcx-Ncy); X the axial substituent, Rn the number of peripheral substitutions, Pcx being the number of 6 p-conjugated bonds, Ncy being the number of 10 p-conjugated bonds (Figure). On first study, we found that X-RnBsub(Pc1-Nc2) have low photostability. Therefore, we moved onto developing a ‘statistical’ synthetic methodology to target highest yields of X-RnBsub(Pc2-Nc1)s, and we did achieve relatively high yields. X-RnBsub(Pc2-Nc1)s therefore could be purified to enable physical characterization. Within a couple past publications, the unique absorption spectra was noted and we have confirmed its uniqueness. The X-RnBsub(Pc2-Nc1)s absorption spectra is as wide as if BsubPc and BsubNc were mixed together. This therefore has good potential to harvest a larger scope of photons from solar or to achieved FRET transfer from a host to emit via an OLED. We then did in-depth first electrochemical characterization, confirmed their electrochemical oxidation and reduction stability and also did in-depth photoluminescence characterization. Therefore, merging X-RnBsub(Pc2-Nc1)s into organic electronic devices as well as other chemistry to synthesis the hybrids is ongoing.Regarding mixed alloys, in the past as we have shown that BsubNcs ended up being a mixed alloyed composition with random bay-position halogenation, that is formed during the reaction of BCl3 with 2,3-dicyanonaphthalene at temperature, which is the process to form the BsubNcs. The random bay-position halogenation has been shown to be impactful in a positive way within OPV devices, negative within OLED devices and also has electrochemical variations and good reversibility. Ongoing, given it is random halogenation, and some of the positive outcomes, this justifies considering additional mixed alloyed compositions.We have also recently shown that mixed alloyed BsubPcs can be formed with three peripheral halogens in the alpha (a) or beta (b) positions, named as Cl-αCl3BsubPc, Cl-βCl3BsubPc, Cl-αF3BsubPc, and Cl-βF3BsubPc. The alloyed mixtures consisted of C1 and C3 isomers of trihalogenated BsubPcs. The physical properties characterization including photophysics, electrochemistry, and thermal characterization, were studied and were also positive and then were engineered into OSCs as electron donors and electrons acceptors to clarify their impact on device performance which had positivity aspects. Therefore, we moved onto developing a set of additional BsubPc mixtures. To be outlined for this presentation, we considered sets of phthalonitrile mixtures to form peripherally halogenated BsubPc mixtures during the formation of BsubPcs from these intermediates. For example, 4,5-dichlorophthalonitrile (Cl2-pn), 4,5-difluorophthalonitrile (F2-pn), tetrachlorophthalonitrile (Cl4-pn), and tetrafluorophthalonitrile (F4-pn) are commercially available compounds that were mixed together and yields a mixture of BsubPc which we named: X-Cl2nF2mBsubPc and X-Cl4nF4mBsubPc (X = Cl or F being a variant, Figure). We then did physical characterization and found positive aspects including electrochemical oxidation and reduction stability. Merging them into organic electronic devices is ongoing and might be present during this presentation time.We did also recently develop additional chemistry methodology to develop additional mixed alloyed BsubPcs. The methodology was to develop phthalonitrile intermediates that have numbers of hydrogen, chlorine and fluorine substitutions and to take them onto the formation of the BsubPc mixed alloys. This is ongoing and may have some aspects to outline during this presentation.We also do computational modelling to look into other relative impacts of the materials being developed, for example the HOMO and LUMO orbital distributions, the local ionization etc. This will also be outlined during this presentation. Figure 1

(Invited) Graphene Ion Blocking Layers for Robust Metal-Halide Perovskite Heterostructures

Despite being only one atomic layer thick, a continuous monolayer of graphene should be completely impermeable to atoms and ions. As such, graphene monolayers could potentially be employed as ion blocking layers in numerous technologies where charge and/or energy transport across a key interface is desirable, but ionic or atomic transport is not. As a key example, the development of metal-halide perovskite/perovskite heterostructures is hindered by rapid interfacial halide diffusion leading to mixed alloys rather than sharp interfaces. This halide diffusion hinders the creation of tailored interfaces that funnel energy or charge in specified directions within energy technologies such as photovoltaic solar cells or light-emitting diodes. To circumvent this issue, we developed an ion-blocking layer consisting of single layer graphene (SLG) deposited between the metal-halide perovskite layers and demonstrate that it effectively blocks anion diffusion in perovskite/perovskite heterostructures. We study these interfaces with a suite of spectroscopy and elemental analysis tools to demonstrate that halides do not diffuse across the graphene-modified interface, whereas control samples without the SLG show rapid homogenization of the halides and loss of the sharp interface. The SLG has little electronic impact on the band alignment and optical properties of the individual semiconductors, as supported by density functional theory calculations, facilitating photoinduced energy transfer across the abrupt heterointerface and light-emitting diodes with no evidence of ion-diffusion during operation. Our results demonstrate that monolayer graphene can be used as an ion blocking layer in a variety of different heterostructures for advanced opto-electronic and electrochemical applications. Further, it establishes a route towards robust perovskite/perovskite heterostructures that are difficult to achieve by other means.