Ga Alloys Research Articles

Carbon diffusivity by means of Snoek relaxation in ternary Fe-26 at%(Al+Ga) alloys with different Al/Ga ratio

Anelastic relaxation in the temperature range from 0 to 300°C (0.1–30 Hz) in ternary Fe-26(Al+Ga)-0.1Tb alloys is experimentally studied and analysed with respect to binary Fe3Al and Fe3Ga intermetallic compounds. The Snoek-type relaxation due to cyclic stress-induced carbon atom jumps between octahedral interstices in the α-Fe based solid solution (Fe-C-Al,Ga) is recorded and analysed. The Snoek-type effect in the ternary Fe-26(Al+Ga)-0.1Tb alloys has a higher activation energy (up to ∼1.2 eV) in comparison to α-Fe-C (0.83 eV). The relaxation effect demonstrated significant broadening with respect to Debye peak with a single relaxation time and splitting into two separated peaks at a certain ratio Al/Ga. Snoek-type effect provides a unique opportunity to measure C atom diffusivity at relatively low temperatures. Influence of the chemical composition and the measuring frequency on the activation parameters in Fe-26(Al+Ga)-0.1Tb alloys are reported and analysed to estimate the impact of Al and Ga atoms on C atom diffusivity in α-Fe based solid solution.

Effect of twist-channel angular pressing on precipitation in Al–Mg–Zn–Ga alloys

Effect of twist-channel angular pressing on precipitation in Al–Mg–Zn–Ga alloys

Effect of Ni doping on mechanical properties and phase transformation in Co–V–Ga high-temperature shape memory alloys

In the present work, the effects of Ni doping on the microstructure and mechanical properties of Co–V–Ga high-temperature shape memory alloy have been studied. It has been found that γ phase occurs in the form of precipitation or even dendrite microstructure when Ni content continuously increases in the alloy. The composition distribution showed the elements Co and Ni segregated in the γ phase, while elements V and Ga concentrated in the martensite phase. Moreover, the phase transition temperature increased by Ni-doping in Co–V–Ga alloys due to the increase in e/a of the alloy. However, the abundant presence of γ phase hindered the shear phase transformation and created a large number of grain boundaries to reduce Ms temperature when Ni content continuously increased. In addition, electron backscattered diffraction (EBSD) results verified that the presence of γ phase could hinder the expansion of cracks, and improve the strength and plasticity of the alloy. Furthermore, it could be found the shape memory effect could maintain a relatively high recovery rate when Ni content was within a certain extent. However, the shape memory effect of the alloy significantly decreased in the presence of γ phase with dendrite microstructure. The current research results not only clarify the influence of Ni doping on the microstructure and mechanical behavior of Co–V–Ga alloys, but also provide guidance for element doping to prepare high-temperature shape memory alloys (HTSMAs) with excellent performance.

The Features of the Phase Composition and Structure of a Rapidly Quenched Ferromagnetic Mn–Al–Ga Alloy

The Features of the Phase Composition and Structure of a Rapidly Quenched Ferromagnetic Mn–Al–Ga Alloy

Factors influencing the martensitic transformation in Ni–Mn–Z (Z = Ga, Sn) Heusler alloys

The martensitic transition temperature of the Ni–Mn–Z (Z = Ga, In, Sn or Sb) generally scales with the average valence electron per atom ( e/a ) ratio. The e/a ratio can be increased either by increasing Ni content in lieu of Mn or Z (Ni-rich) or by substituting Mn for Z (Mn-rich). While the Mn-rich alloys display the expected scaling behaviour of the martensitic transition temperature, the Ni-rich alloys, with the exception of Z = Ga alloys, do not exhibit any dependency on the e/a ratio. By carefully studying and comparing the structure, local structure and the physical properties of the Ni-rich and Mn-rich Ni–Mn–Ga and Ni–Mn–Sn alloys, the cause of the difference in behaviour is identified. The off-stoichiometry brought about by increasing the Ni or Mn content, results in the formation of a new local structural environment in addition to the Heusler-like environment. If either of the two local structural environments is martensitic, then the resulting Ni-rich or Mn-rich alloy also exhibits martensitic transformation.

Room temperature growth of CsPbBr3 single crystal for asymmetric MSM structure photodetector

UV–visible broadband light harvesting ability is critical for photodetectors, and all inorganic perovskite CsPbBr3 is regarded as a promising candidate as the response active material. Herein, a saturated-solution crystallization method is employed to synthesize CsPbBr3 single crystal. Temperature-dependent photoluminescence spectra with one-photon and two-photon excitation are systematically investigated, determining a large exciton binding energy of 39.8 meV. This allows the stable excitonic emission of CsPbBr3 single crystal at room temperature. Subsequently, an asymmetric structure CsPbBr3 photodetector is fabricated by using InGa alloy as the Ohmic electrode and Au as the Schottky electrode. At -8 V, the device exhibits a prominent response to the irradiation from UV to green band with a maximum responsivity of 2.56 A/W, an external quantum efficiency of 580 %, and a detectivity of 1.24 × 1013 Hz1/2 W−1. In addition, the CsPbBr3 photodetector also presents rapid response speeds at both reverse and forward bias voltages and self-powered characteristics owing to the Schottky depletion layer underneath the Au electrode. The demonstration of asymmetric metal-semiconductor-metal (MSM) structure photodetector presents a promising pathway toward next-generation CsPbBr3 optoelectronic devices.

Discharge performance of Al-0.1Sn-0.1In-0.05Ga alloy for Al–air battery anodes

The performance of Al-0.1Sn-0.1In-0.05Ga alloys as anodes for Al–air batteries is investigated for low carbon development needs. Low melting point elemental metals were added to high purity Al (99.9999 %) using micro alloying, either in a diffuse distribution or as a second phase, depending on their solid solubility in the Al. The correlation between the microstructure and electrochemical properties of Al-0.1Sn-0.1In-0.05Ga alloys was established. The experiments were conducted in a 4.0 mol/l NaOH solution. The electrochemical characteristics of the Al-0.1Sn-0.1In-0.05Ga anodes were assessed by using potentiodynamic polarization, electrochemical impedance spectroscopy, and galvanostatic discharge experiments. It is indicated that the inclusion of Sn, In, and Ga elements results in improved corrosion resistance and discharge activity in the anode composed of Al. This can be attributed to the presence of nano-scale second phase particles and a uniform microstructure in the Al-0.1Sn-0.1In-0.05Ga alloy, which effectively inhibits localized crystallographic corrosion. In comparison to pure Al, the Al-0.1Sn-0.1In-0.05Ga alloy exhibits a reduction in corrosion current density by 24.77 % and an increase in anode efficiency by 40 %. When discharged at a current density of 10 mA/cm2, an Al–air battery with an Al-0.1Sn-0.1In-0.05Ga anode exhibits a discharge voltage of 1.523 V, a discharge capacity of 2214 Ah/kg, and an anode efficiency of 74.31 %. The research has the potential to advance Al–air batteries' progress and significantly contribute to global sustainability efforts.

Diffusive and displacive phase transitions in Fe-Ga alloys

Phase transitions between structurally ordered phases in Fe–Ga alloys have been studied upon their heating to 850 °C and subsequent cooling to room temperature by neutron diffraction in real-time mode. The transitions between four types of phases have been analyzed: D03 → L12 (both cubic phases), L12 ↔ D019 (cubic – hexagonal), D019 ↔ A2 (hexagonal – cubic). It has been established that all phase transitions include stage of the formation of a disordered state and have a combined, diffusive-displacive nature. The diffusion stages are necessary for the disordering and ordering of the structure, the displacive stage provides a change in the type of the crystal lattice. It can be concluded that the formation of an intermediate disordered state followed by a transition to the final equilibrium state is less energy-consuming than the direct transition to the final state. During the observed transformations, no traces of predicted intermediate structurally ordered tetragonal phases were found. These results may provide new insight into the microscopic basis for the formation of enhanced magnetostriction in Fe–Ga alloys.

Probing Ti–doped (Al–Ga) surface as Nanosensor for adsorbing the S- & N-containing heterocyclic compounds

Aluminum–Gallium doped with titanium by using ONIOM method through structural, electrical, and thermodynamic properties was studied in detail. Crystal structure of Ti–(Al–Ga) surface was coated by S- & N-heterocyclic carbenes of benzotriazole (BTA), 2-mercaptobenzothiazole (2MBT), 8-hydroxyquinoline (8HQ) and 3-amino-1,2,4-triazole-5-thiol (ATR). The “NMR” spectroscopy of the adsorption of BTA, 2MBT, 8HQ, and ATR on the Ti–doped Al–Ga nanoalloy surface represents that this surface can be employed as the magnetic S- & N-heterocyclic carbene sensors. In fact, “Ti” site in “Ti–(Al–Ga)” nanoalloy surface has bigger interaction energy amount from “Van der Waals’ forces” with BTA, 2MBT, 8HQ, and ATR that might cause them large stable towards coating data on the nanosurface. It has been estimated that the criterion for choosing the surface linkage of “S” and “N” atom in BTA, 2MBT, 8HQ, and ATR in adsorption sites can be impacted by the existence of close atoms of aluminum and gallium in the “Ti–(Al–Ga)” surface. The fluctuation of “NQR” has estimated the inhibiting role of BTA, 2MBT, 8HQ, and ATR for Ti–doped Al–Ga alloy nanosheet due to “S” and “N” atoms in the benzene cycle of heterocyclic carbenes being near the monolayer surface of ternary “Ti–(Al–Ga)” nanoalloy. Moreover, “IR” spectroscopy has exhibited that Ti–doped Al–Ga alloy nanosheet with the fluctuation in the frequency of intra–atomic interaction leads us to the most considerable influence in the vicinage elements generated due to inter–atomic interaction. Comparison to amounts versus dipole moment has illustrated a proper accord among measured parameters based on the rightness of the chosen isotherm for the adsorption steps of the formation of BTA @Ti–(Al–Ga), 2MBT @Ti–(Al–Ga), 8HQ @Ti–(Al–Ga), and ATR @Ti–(Al–Ga) complexes. Thus, the interval between sulfur, nitrogen and oxygen atoms in BTA, 2MBT, 8HQ, and ATR during interaction with transition metal of “Ti” in “Ti–(Al–Ga)” nanoalloy, (N→Ti, O→Ti, S→Ti), has been estimated with relation coefficient of R² = 0.9509. Thus, the present has exhibit the influence of “Ti” doped on the “Al–Ga” surface for adsorption of S- & N-heterocyclic carbenes of BTA, 2MBT, 8HQ, and ATR by using theoretical methods. Furthermore, the “partial electron density” or “PDOS” has estimated a certain charge assembly between Ti–(Al–Ga) and S– & N–heterocycles of BTA, 2MBT, 8HQ, and ATR which can remark that the complex dominant of metallic features and an exact degree of covalent traits can describe the augmenting of the sensitivity of “Ti–(Al–Ga)” surface as a potent sensor for adsorption of BTA, 2MBT, 8HQ, and ATR heterocycles.

Defect induced ferromagnetism in Mn3Ga

Ni-substituted Mn3Ga displays a weak ferromagnetism embedded in an antiferromagnetic (AF) phase. Upon field cooling, the alloy exhibits exchange bias and an open hysteresis loop, signifying kinetic arrest at room temperature. For the first time, a kinetic arrest is seen in a compound due to the first order transition of an embedded defect phase. A systematic study of crystal structure, local structure, and magnetic properties of Mn 3−x Ni x Ga (x = 0, 0.25) alloys reveal the origin of ferromagnetism in Mn2.75Ni0.25Ga is due to the segregation of a Heusler-type environment around Ni in the cubic Mn3Ga matrix. Upon temper annealing at 400 ∘C, these local structural defects around the Ni phase separate into a modulated ferromagnetic (FM) Ni-Mn-Ga Heusler phase. A strong interaction between the AF host and the FM defect phase gives rise to exchange bias. The first-order transition of the defect phase seems to be responsible for the observed kinetic arrest in Mn2.75Ni0.25Ga.

Magnetostrictive wires-epoxy resin composite structures for human motion energy harvesting

Encapsulation of magnetostrictive alloy wires in epoxy resin has great potential for energy harvesting and can be applied to energy harvesting in human motion. In this work, a magnetostrictive wire-epoxy resin arch composite structure was proposed for harvesting energy generated by foot motion. A prestress was introduced during the resin curing process, and the relationship between the output voltage and material properties was derived based on the Villari effect. Three kinds of Fe-based magnetostrictive wires were prepared and their magnetic properties were measured, then a prototype single-layer arch composite structure was fabricated and an experimental platform was built for testing, and the amplitude of the output open-circuit voltage could reach 936 mV under an impact pressure of 750 N, which proved that the Fe–Ga alloy composite structure was superior to Fe–Co and Fe–Ni alloys in energy harvesting. The double-layer arch-shaped Fe–Ga composite structures energy harvesting prototype outputs a maximum voltage of up to 940 mV in foot energy harvesting experiments, and collected a maximum power of up to 2.45 mW at a step frequency of 3.5 Hz. Consequently, this work emphasized the feasibility of magnetostrictive alloy-epoxy composite structures for energy harvesting in human motion and the potential for developing new ways of energy harvesting.

Influence of main-group elements on structural, electronic, magnetic and half-metallic properties of DO3-type Mn3Z (Z = Al, Ga, In, Si, Ge, Sn, P, As and Sb) alloys - A DFT study

We investigate the influence of main-group elements belonging to group III (Al, Ga and In), IV (Si, Ge and Sn) and V (P, As and Sb) on structural, electronic, magnetic and half-metallic (HM) properties of DO3-type Mn3Z alloys using density functional theory (DFT). In particular, we emphasize on the correlation between structural parameters (lattice constant) and the changes in electronic and magnetic properties of Mn3Z alloys. From full geometry optimization results, we find that the entire Mn3Z alloys stabilized to ferrimagnetic ordering. Further, the spin-polarized density of states (DOS) calculation reveals that Mn3Z (Z = Al, Si, Ge, Sn, As and Sb), Mn3Ga and Mn3In alloys exhibit, respectively, half-metallic (HM), nearly half-metallic (NHM) and metallic nature. While, the Mn3P alloy displays spin-gapless semiconducting (SGS) feature, in which spin-up and spin-down channels show metallic and spin-gapless feature, respectively. The Mn3Al, Mn3Z (Z = Si, Ge and Sn) and Mn3Z (Z = P, As and Sb) alloys follow Slater-Pauling rule well, and gives 100 % spin-polarization at the Fermi energy (EF) with total integer magnetic moment of 0, 1 and 2 μB/f.u, respectively. The contribution to total magnetic moment in all the Mn3Z alloys comes predominantly from Mn(Y) atoms. The molecular orbital (MO) hybridization mechanism is proposed to rationalize the HM band gap.

Structural, Magnetocaloric, and Magnetic Properties in Heusler Ni50Mn35In10X5 (X = Ga, Fe and Al) Alloys

The structural, magnetocaloric, and magnetic characteristics in Heusler Ni50Mn35In10X5 (X = Ga, Fe, and Al) alloys were examined using X-ray diffraction and field-dependent magnetization measurements. All samples exhibited a mixture structure of cubic L21 and tetragonal L10 and underwent second-order magnetic transitions at TC(Al5) = 220 K, TC(Ga5) = 252 K, and TC(Fe5) = 298 K. The Ga5 alloy exhibited structural change as indicated by a thermal hysteresis that may be seen in the saturation magnetic field in the M(T) dependences. The transition at the TC point from a ferromagnetic to a paramagnetic state caused a drop in magnetization, supported by thermal hysteresis, at a low magnetic field (0.01 T). On the other hand, the Fe5 alloy presented a gradual decrease in magnetization with similar hysteresis behavior, also at a low magnetic field (0.01 T), whereas at 0.1 T of field, no features characteristic of this transition were detected. This could be due to a large difference in the metallic radius of Fe compared to that of In. Otherwise, magnetic investigations demonstrated that the replacement of In with Al may cause the structural transformation temperatures and TC to be shifted to low temperatures. The present results imply that the structural transformation temperatures and the transition itself are highly dependent on chemical composition. Furthermore, under a magnetic field change of 5 T, the maximum magnetic entropy changes of 0.6 J/kg K, 1.4 J/kg K, and 2.71 J/kg K for the Ga5, Fe5, and Al5 alloys, respectively, were determined by their TC. Refrigeration capacity values were found to be 25 J/kg, 74 J/kg, and 98 J/kg at µ0∆H = 5 T. These ribbons are viable candidates for multifunctional applications due to their cheaper cost and their physical characteristics disclosed during the magnetostructural transition, which takes place close to the room temperature.

Magnetic and transformation properties of Ni2MnGa combinatorically substituted with 5 at.% of transition elements from Cr to Cu – Experimental insight

Heusler Ni–Mn–Ga alloys with martensitic transformation being multiferroic materials exhibit magnetic shape memory (MSM) phenomena and moreover, these are touted for magneto– and multi–caloric effect (MCE). MCE benefits from high saturation magnetization and also large variability and sensitivity of transformation temperatures on alloying. In contrast, MSM phenomena are limited by low temperatures of both ferromagnetic and ferroelastic transformations. In an attempt to increase or modify the transformation temperatures and to understand the physical fundamentals beyond transformation variations and magnetic ordering, we experimentally investigate the magnetic and transformation properties in Ni2MnGa alloyed with transitional elements spanning from Cr to Cu. These elements are consecutively substituted on Ni, Mn, and Ga sites, to establish the effect of chemical substitution and elemental evolution. The elemental dependence of saturation magnetization, magnetocrystalline anisotropy, Curie temperature, and martensitic transformation temperatures are compared with (non–)stoichiometric Ni–Mn–Ga Heusler compounds. The observed behavior is complex and there are no clear trends of transformation temperatures as a function of the number of valence electrons or of non–bonding electrons per atom. The saturation magnetization at 10 K seems to follow the Slater–Pauling curve particularly for Ni substitution. Obtained results can serve as useful rectification for the theoretical prediction of new Ni–Mn–Ga–X Heusler alloys.

Influence of Various Alloying Element Additions on Microstructure and Magnetic and Mechanical Properties and Corrosion Behavior of Cast Fe–Ga–Z Shape Memory Alloys

Fe–Ga alloys are attractive materials where high mechanical strength, toughness, ductility, and large low-field magnetostriction combine to give unique properties. Adding alloying elements is an effective method to further enhance these properties. In order to integrate these alloys into the operating environments, e.g., micro-robots and magnetic actuators, the corrosion behavior should be addressed. This work analyzed the microstructure, magnetization, hardness, and corrosion properties of Fe81Ga19−xZx (X = 5 at.% of Ni, Mn, or Ti, and 2 at.% Al; separately) alloys. X-ray diffraction (XRD), scanning electron microscope-electron (SEM), vibrating sample magnetometer (VSM), Vickers hardness (HV), and a potentiostat were used for characterization. XRD revealed that the prominent peak belongs to the bcc disorder A2 phase and a small peak for the cubic order L12 phase. Fe–Ga–Al alloy got the maximum Ms value, while Fe–Ga–Mn alloy gained the lowest one. However, the Mr and Hc properties for Fe–Ga alloy were distinctly improved by adding Al but slightly affected by doping Mn. Addition of Ti achieved the highest hardness, followed by Ni, Mn, and Al. The microstructure of the different alloys significantly influenced their corrosion behavior. Fe–Ga–Mn alloy with the fine globular grain structure showed the lowest corrosion rate (C R = 0.03 mm/year), whereas Fe–Ga–Al alloy with the coarse longitudinal grains exhibited the highest corrosion rate (C R = 0.19 mm/year).

The Structure and Martensitic Transformation of Deformed Ni−Mn−Ga Alloys

The Structure and Martensitic Transformation of Deformed Ni−Mn−Ga Alloys

Influence of Si on the Structure and Martensitic Transformation in Deformed Ni–Mn–Ga Alloys

Abstract—The studying the effect of multiaxial isothermal forging on the microstructure and martensitic transformation in the Ni58Mn18Ga24 alloy is presented. Forging was carried out in two stages: stage 1 − forging at 700°C (4 passes, true degree of deformation e ≈ 1.64), stage 2 − forging at 500°C (1 pass, e ≈ 0.24). Forging led to the transformation of the original equiaxed grain structure. As a result of the 1st stage of processing, no new grains are formed. The new recrystallized grains are observed only after the 2nd stage of deformation, the proportion of which is very small. Apparently, the mechanism of fragmentation of the grain structure at the first stage is not triggered due to insufficient defect density at a deformation of 700°C. The characteristic temperatures of martensitic transformation are shifted to the low temperature region. The anharmonic change in the sample length is observed in the region of martensitic transformation for the both treated states. In general, this indicates a low level of defect density and internal stresses in the sample.

Effect of Ga Partial Substitution on the Structural and Magnetic Properties of Heusler Ni–Mn–Ga Alloys

Abstract—The effect of doping with Cu and Zn atoms on the magnetic and structural properties of the cubic and tetragonal phase of the Heusler Ni2Mn1.125Ga0.875 alloy has been investigated in the framework of density functional theory. Partial substitution of Ga atoms by Cu and Zn atoms leads to a decrease in the energy difference between the ferromagnetic and ferrimagnetic states of the cubic phase and an increase in the energy barrier between the cubic and tetragonal phase. The latter observation indirectly points to the increase in the structural transition temperature observed experimentally. Within the framework of calculations of exchange interaction parameters from first principles and Monte Carlo modeling of temperature dependences of magnetization, a phase T–x diagram is constructed. It is shown that the Curie temperature of the tetragonal phase decreases significantly compared to the Curie temperature of the cubic phase with increasing Cu and Zn content due to an increase in the inter-sublattice antiferromagnetic interaction between Mn atoms.

Polarization Properties of Wurtzite III-Nitride Alloys Using the Hexagonal Reference Structure

The layered-hexagonal structure was proposed as a reference by Dreyer et al. [Phys. Rev. X 6, 021038 (2016)] to determine polarization properties of wurtzite materials. Using this reference in the context of the Berry-phase theory, we study the polarization of wurtzite III-nitride ternary alloys Al x Ga1−x N, In x Ga1−x N and In x Al1−x N. We report composition-dependent expressions of the spontaneous and piezoelectric polarizations and compare these values to the zincblende results. It is found that both spontaneous and piezoelectric components exhibit nearly linear dependence on alloy concentration, which means they follow the linear behavior predicted by Vegard’s law. The total-polarization charge of the quaternary-alloy heterostructure Al x In y Ga1−x−y N/GaN is also investigated based on the hexagonal structure. We show that the polarization charge results to be zero at certain Al and In contents, giving heterostructures free of built-in electric fields and thus allowing the design of high-efficiency optical devices. Furthermore, we compute the total-polarization charge of Al x Ga1-x N/GaN, In x Ga1−x N/GaN and In x Al1−x N/GaN. These values are compared to available theoretical and experimental data in order to validate the results of our simulation.

Mechanical and Corrosion Properties of Hot-Extruded Mg–Zn–Ga Alloys

Mechanical and Corrosion Properties of Hot-Extruded Mg–Zn–Ga Alloys