Tantalum Aluminum Research Articles

Evaluation of 2D Tantalum Carbide MXene for Room to Mid‐temperature Thermoelectric Applications

AbstractTantalum carbide MXene (Ta4C3Tx) were synthesized via HF etching of the Al intermediate layer from the parental tantalum aluminium carbide MAX phase (Ta4AlC3). The structural and vibrational studies confirm the formation of MXene from the MAX phase without disturbing the hexagonal crystal structure. The synthesized samples were analysed using XRD to understand the phase structure. In and out of plane vibrational properties were examined by Raman spectrometer. XPS confirms the successful HF etching of Al in MXene phase and all other elemental configurations. HR‐SEM and HR‐TEM revile the exfoliated layered structure of the MXene and hexagon diffraction pattern of the tantalum carbide MXene sample with increased d‐spacing. The TGA analysis demonstrated the thermal stability of the as‐synthesized post measured compounds. The synthesized tantalum carbide MXene shows stable thermoelectric properties over six thermal cycles. The temperature dependent transport properties were measured from 303 K to 803 K. Ta4C3Tx MXene shows a maximum Seebeck coefficient of 13.8 μV/K and a power factor of 1.88 μW/mK2 with the low lattice thermal conductivity of 5.42 W/mK at 803 K. In this present investigation, Tantalum carbide MXene demonstrated a decent thermoelectric property with high thermal cycling stability.

Influence of aluminum addition on structure, hardness, and oxidation resistance of Ta1−xAlxN thin films

Ta1−xAlxN thin films with 5, 15, and 40 at.% Al addition were co‐deposited by reactive magnetron sputtering and characterized by Rutherford backscattering spectroscopy (RBS), grazing angle X‐ray diffraction (GAXRD), X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), nanohardness, and oxidation tests. GAXRD and XPS analyses showed, regardless of the % Al added, the non‐existence of ternary nitride Ta1−xAlxN, but always as individual binary nitrides, TaN and AlN. Sample TaAlN_15 obtained the highest hardness and H3/E2 values, possibly due to the AlN grains presence, which were efficient in distorting the TaN lattice. All samples failed oxidation tests at 873 K, showing that the Al addition was not efficient in improving this property for tantalum aluminum nitride thin films.

Aluminum tantalum oxide thin films deposited at low temperature by pulsed direct current reactive magnetron sputtering for dielectric applications

This research aims at studying aluminum tantalum oxide thin films (AlxTayOz) deposited at low temperature for dielectric applications. These ternary oxide layers are synthesized at 180 °C by physical vapor deposition (PVD), specifically the mid-frequency pulsed direct current reactive magnetron sputtering. The deposition process uses targets made of a mixture of aluminum and tantalum in various proportions. Four target compositions are studied containing 95 at.%, 90 at.%, 80 at.%, and 70 at.% of aluminum, corresponding to 5 at.%, 10 at.%, 20 at.%, and 30 at.% of tantalum, respectively. The ternary oxide thin films of AlxTayOz are compared to aluminum oxide (AlxOz) and tantalum oxide (TayOz) layers produced in the same experimental conditions. The AlxTayOz thin films are dense, uniform, and amorphous regardless of the experimental conditions used in this study. Their chemical composition changes as a function of the target composition. The oxygen flow used during deposition also affects the chemical composition of the oxide layers and the deposition rate. The oxide thin films with tantalum are deposited at higher deposition rates and contain more oxygen. Tantalum also promotes the amorphization of the oxide layers. The highest dielectric strength is measured for the thin film containing a low amount of tantalum combined with a high amount of oxygen.

Self-induced Q-switched fiber laser using tantalum aluminum carbide as a passive modulator

A self-induced Q-switched erbium-doped fiber laser operating at 1563 nm was achieved by integrating a passive modulator based on tantalum aluminum carbide (Ta2AlC) MAX phase film embedded into polyynyl alcohol. The modulator, serving as a saturable absorber (SA), established a modulation depth of 9% and a saturation intensity of 0.3 MW cm−2. Upon integration of the film SA, a stable Q-switched fiber laser was obtained, generating pulses with a minimum width of 7.6 µs at a repetition rate of 45.1 kHz, within a pump power range of 24.9–59.7 mW. The corresponding maximum average output power, maximum pulse energy, and highest peak power were determined at 1.6 mW, 36.2 nJ, and 4.7 mW, respectively. The RF fundamental spectrum exhibited a good signal-to-noise ratio of 61 dB, indicating excellent pulse signal quality. This demonstration of Ta2AlC MAX phase film Q-switched laser may open promising possibilities for scientific applications such as material processing.

Simulations on the shielding performance of composite materials around Jupiter’s radiation belts

The radiation environment in the vicinity of Jupiter is extremely harsh. In this context, dominant high-energy electrons are the main cause of the total ionizing dose that seriously threatens the service life of electronic devices aboard spacecraft. In this study, we explore the shielding effect of aluminum–tantalum composite materials in the energy spectrum of the radiation environment of a probe orbiting Jupiter and the planet’s gravity assist orbit at the edge of the solar system by using Monte Carlo simulations. The results show that when the shielding material was sufficiently thick, the composite shield was superior to a shield composed of a single element. Moreover, the lower the apogee of the orbit around Jupiter was, the higher was the flux in the energy spectrum of the electrons, and it was advantageous to use a thin material in the composite shield in this case. As the thickness of the material increased, the mass ratio of Al in the optimal ratio of the Al–Ta composite material gradually increased. The results of this study provide a reference for designing strong shielding materials to protect against radiation in deep space exploration.

Operation of a passively mode‐locked Tm:YAG laser with tantalum aluminum carbide as a saturable absorber

AbstractIn this paper, a compact diode‐pumped continuous wave (CW) and passively Q‐switched mode‐locked (QML) Tm:YAG lasers operation on the 3F4–3H6 transition is realized by using tantalum aluminum carbide (Ta4AlC3) phase ceramic (MAX) material as a saturable absorber (SA). The first stable QML operation of the mid‐infrared Tm:YAG laser at 2012.38 nm is demonstrated with a Ta4AlC3‐SA. A stable QML Tm:YAG laser was achieved when the absorption pumping power reached 14 W. Under QML mode, Tm:YAG laser generated a maximum average output power of 560 mW at 2012.38 nm with an optical‐to‐optical conversion efficiency of 4%, corresponding to a shortest pulse duration of 541 ps and a high repetition rate of 168 MHz. The experiment shows that Ta4AlC3‐SA is an attractive candidate for diode‐pumped CW and QML mid‐infrared all‐solid‐state lasers emitting around 2.0 μm.

Design optimization of an electron-to-photon conversion target for ultra-high dose rate x-ray (FLASH) experiments at TRIUMF

Objective. To develop a bremsstrahlung target and megavoltage (MV) x-ray irradiation platform for ultrahigh dose-rate (UHDR) irradiation of small-animals on the Advanced Rare Isotope Laboratory (ARIEL) electron linac (e-linac) at TRIUMF. Approach. An electron-to-photon converter design for UHDR radiotherapy (RT) was centered around optimization of a tantalum–aluminum (Ta–Al) explosion-bonded target. Energy deposition within a homogeneous water-phantom and the target itself were evaluated using EGSnrc and FLUKA MC codes, respectively, for various target thicknesses (0.5–1.5 mm), beam energies (E e− = 8, 10 MeV) and electron (Gaussian) beam sizes ( = 2–10 mm). Depth dose-rates in a 3D-printed mouse phantom were also calculated to infer the compatibility of the 10 MV dose distributions for FLASH-RT in small-animal models. Coupled thermo-mechanical FEA simulations in ANSYS were subsequently used to inform the stress–strain conditions and fatigue life of the target assembly. Main results. Dose-rates of up to 128 Gy s−1 at the phantom surface, or 85 Gy s−1 at 1 cm depth, were obtained for a 1 × 1 cm2 field size, 1 mm thick Ta target and 7.5 cm source-to-surface distance using the FLASH-mode beam (E e− = 10 MeV, 2 = 5 mm, P = 1 kW); furthermore, removal of the collimation assembly and using a shorter (3.5 cm) SSD afforded dose-rates >600 Gy s−1, albeit at the expense of field conformality. Target temperatures were maintained below the tantalum, aluminum and cooling-water thresholds of 2000 °C, 300 °C and 100 °C, respectively, while the aluminum strain behavior remained everywhere elastic and helped ensure the converter survives its prescribed 5 yr operational lifetime. Significance. Effective design iteration, target cooling and failure mitigation have culminated in a robust target compatible with intensive transient (FLASH) and steady-state (diagnostic) applications. The ARIEL UHDR photon source will facilitate FLASH-RT experiments concerned with sub-second, pulsed or continuous beam irradiations at dose rates in excess of 40 Gy s−1.

Passively Q-switched Tm:YAP laser with a tantalum aluminum carbide saturable absorber.

Tantalum aluminum carbide (Ta4AlC3) phase ceramic (MAX) material has attracted much attention because of its high conductivity, high strength, corrosion resistance, and good optical properties. However, there are too few reports on lasers with Ta4AlC3-based saturable absorbers (SAs). We prepared and characterized a Ta4AlC3-based SA whose nonlinear absorption performances were achieved at a 2 µm waveband range and which was used in a passively Q-switched (PQS) Tm:YAP laser. In the PQS mode, a maximum average output power of 0.78 W was achieved with the central output wavelength of 1991.86 nm from a PQS Tm:YAP laser, corresponding to a pulse duration of 926 ns at 143.8 kHz.

Arc-shaped fiber coated with Ta2AlC MAX phase as mode-locker for pulse laser generation in thulium/holmium doped fiber laser

Tantalum aluminum carbide (Ta2AlC)/arc-shaped fiber-based saturable absorber (SA) was utilized to induce mode-locked pulses in a thulium-holmium doped fiber (THDF) laser. A soliton mode-locked laser was observed at a threshold pump power of 120 mW with the wavelength centered at 1915 nm, 3-dB spectral bandwidth of 3.0 nm, and pulse width of 1.36 ps. The generated laser exhibits output power and pulse energy of 1.75 mW and 0.14 nJ, respectively. A high signal-to-noise ratio (SNR) value of more than 55 dB was achieved. These experimental results have proved the potential of Ta2AlC MAX Phase as an SA material that can find application in ultrafast photonics.

2\xa0\u03bcm passively mode-locked thulium-doped fiber lasers with Ta2AlC-deposited tapered and side-polished fibers

In this work, mode-locked thulium-doped fiber lasers operating in the 2 µm wavelength region were demonstrated using tantalum aluminum carbide (Ta2AlC)-based saturable absorbers (SAs) utilizing the evanescent wave interaction. The Ta2AlC MAX Phase was prepared by dissolving the Ta2AlC powder in isopropyl alcohol and then deposited onto three different evanescent field-based devices, which were the tapered fiber, side-polished fiber, and arc-shaped fiber. Flame-brushing and wheel-polishing techniques were used to fabricate the tapered and arc-shaped fibers, respectively, while the side-polished fiber was purchased commercially. All three SA devices generated stable mode-locked pulses at center wavelengths of 1937, 1931, and 1929 nm for the tapered, side-polished, and arc-shaped fibers. The frequency of the mode-locked pulses was 10.73 MHz for the tapered fiber, 9.58 MHz for the side-polished fiber, and 10.16 MHz for the arc-shaped fiber. The measured pulse widths were 1.678, 1.734, and 1.817 ps for each of the three SA devices. The long-term stability of the mode-locked lasers was tested for each configuration over a 2-h duration. The lasers also showed little to no fluctuations in the center wavelengths and the peak optical intensities, demonstrating a reliable, ultrafast laser system.

Improved Sensing Capability of Integrated Semiconducting Metal Oxide Gas Sensor Devices.

Semiconducting metal oxide (SMO) gas sensors were designed, fabricated, and characterized in terms of their sensing capability and the thermo-mechanical behavior of the micro-hotplate. The sensors demonstrate high sensitivity at low concentrations of volatile organic compounds (VOCs) at a low power consumption of 10.5 mW. In addition, the sensors realize fast response and recovery times of 20 s and 2.3 min, respectively. To further improve the baseline stability and sensing response characteristics at low power consumption, a novel sensor is conceived of and proposed. Tantalum aluminum (TaAl) is used as a microheater, whereas Pt-doped SnO2 is used as a thin film sensing layer. Both layers were deposited on top of a porous silicon nitride membrane. In this paper, two designs are characterized by simulations and experimental measurements, and the results are comparatively reported. Simultaneously, the impact of a heat pulsing mode and rubber smartphone cases on the sensing performance of the gas sensor are highlighted.

Processes of Self-Organization and Evolution of the Microstructure of Metals and Intermetallic Compounds under a Strong External Action

Electron-microscopic studies of the processes of self-organization and evolution of the microstructure of metals and intermetallic compounds under different strong external actions are carried out. Special attention is given to the study of processes controlling the formation of explosively welded joints. Welded joints such as copper–tantalum, copper–titanium, aluminum–tantalum, titanium–orthorhombic titanium aluminide, steel–steel, etc., are studied. It is shown that the main mechanisms of self-organization in metals, which lead to the formation of stable joints after a very strong and short-term explosive action, are the fragmentation of two types, i.e., the formation of cusps and splashes, the formation of quasi-wave and wave interfaces, and local melting. The self-organization processes are also studied under the action of another kind of strong external action—severe plastic deformation by high-pressure torsion (HPT). It is shown that the effect of the self-locking of dislocations in the intermetallic compounds disappears upon torsion.

Physical characterization and electrical conductivity of Li1.2Ti1.8Al0.2(PO4)3 and Li1.2Ta0.9Al1.1(PO4)3 NASICON material

Sodium superionic conducting materials (NASICON) are promising solid electrolytes for Li-ion batteries and suitable to be used in the area that requires high energy density as well as rechargeable power sources. Fabrication of all-solid-state Li battery with non-flammable ceramics electrolyte has been strongly required to solve safety issues of present Li batteries. In this study, lithium titanium aluminium phosphate Li1+xTi2-xAlx(PO4)3, LTAP (x = 0.2) and lithium tantalum aluminium phosphate Li1+2xTa1-xAlx+1(PO4)3, LTaAP (x = 0.1) were prepared via conventional solid state reaction techniques at various sintering temperature ranging from 700 to 1000 °C. LTAP and LTaAP compositions attain their optimum sintering temperature at 800 °C. Physical properties of LTAP and LTaAP show the bulk density of 2.83 and 3.63 g/cm3 which resulted into high densification of the material. The XRD analysis revealed NASICON crystalline phase dominated by LiTi2(PO4)3 and minor impurity phases for LTaAP composition. Bulk conductivity values for LTAP and LTaAP were found to be 1.06 x 10-4 and 9.854 x 10-6 S/cm at room temperature. LTAP had better conductivity behavior compare to LTaAP composition which could be due to differences in their ionic radius (titanium, 0.605 nm tantalum, 0.64 nm and the aluminium, 0.53 nm) in sizes, though the conductivity obtained for both compositions has the capacity to serve as solid electrolyte material could be used in lithium ion rechargeable battery.

The structure of molten zones in explosion welding (aluminium–tantalum, copper–titanium)

Investigations were carried out into the relief of the flat- and wave-shaped interfaces for explosion-welded aluminium–tantalum and copper–titanium welded joints. For these systems, characterized by a relatively high mutual solubility of the initial elements, the results show a typical set of the structures of the interfaces replacing each other with the intensification of the welding conditions. The unusual shape of the projections on the flat interfaces was found. They are similar to splashes, which form on the surface of the liquid, although they are solid-phase splashes. The vortex structure of the zones of local melting was also detected. The unusual shape of the waves was found: in the presence of mutual solubility they consist of the specially ordered set of projections. It may be assumed that this is caused by the formation of intermetallic compounds on the surface of the projections. The processes of self-organization, ensuring the evolution of the relief of the interface in the intensification of the welding conditions, have been investigated. The role of intermetallic compounds in these self-organization processes is clarified.

Optical band gap and infrared phonon modes of (La_029Sr_071)(Al_065Ta_036)O_3 (LSAT) single crystal from infrared to ultraviolet range spectroscopic ellipsometry

Single crystal lanthanum strontium aluminum tantalum oxide, (LaAlO3)0.29(SrTa1/2Al1/2O3)0.71 or (La0.29Sr0.71)(Al0.65Ta0.36)O3 (LSAT), is a substrate for the epitaxial growth of oxide thin films. Optical properties in the form of the complex dielectric function (e = e1 + ie2) and index of refraction (N = n + ik) of LSAT from 0.033 to 5.887 eV are determined from spectroscopic ellipsometry measurements. The indirect band gap and lowest direct gap energies are identified at 4.72 and 5.70 eV, respectively. Eight infrared active phonon modes are identified in the 283 to 1127 cm−1 spectral range and ascribed to chemical bonding.

Epitaxy from the liquid phase: tuning metastable phases in Fe–Pd thin films by laser-assisted rapid solidification on substrates

Epitaxy by crystallization of thin liquid films on suitable substrates constitutes an alternative approach to molecular beam epitaxy, particularly if metastable phases are required. Employing laser-assisted rapid solidification, we demonstrate for the example of the body-centred-cubic, body-centred-tetragonal, face-centred-tetragonal and face-centred-cubic phases of Fe7Pd3 thin films, how the interplay of cooling rate and substrate-assisted nucleation affects the resulting metastable crystal phase and epitaxial relationship. Exemplarily employing lanthanum strontium aluminium tantalum oxide, MgO, and Si single crystals as substrates, this is experimentally demonstrated by an x-ray diffraction study and pole figure measurements. The underlying solidification kinetics are clarified using finite element calculations on the resulting time–temperature profile. Employing secondary ion mass spectroscopy we additionally demonstrate that the absence of interdiffusion is a central requirement for successful application.

Temperature dependence of TaAlOx metal-insulator-metal capacitors

Structural and electrical properties of amorphous tantalum aluminum oxide (TaAlOx) films deposited using rf magnetron sputtering are investigated using metal-insulator-metal (MIM) capacitor structures with Au as metal electrodes. Crystallinity of the deposited films was studied using grazing incidence x-ray diffraction analysis. The frequency dependence of temperature coefficient of capacitance, an important parameter for precision MIM capacitors, is studied using the Au/TaAlOx/Au stacked layer. The effects of annealing temperature and the ambient on the physical and electrical properties of TaAlOx-based high-k MIM capacitors are reported. Low nonlinearity in capacitance values was found for samples annealed in O2 ambient. Dielectric loss and permittivity are found to increase with increase in temperature.

Synthesis, Structure and Properties of Niobium Aluminum Oxynitride and Tantalum Based Compound Prepared through Citrate Route

The oxynitrides with composition A1-xBx(OyNz) (A: Nb and Ta, B: Al) were studied in preparation through citrate route and NH3 nitridation. In the case of Nb, the product of x = 0.5 prepared at 1000 °C was a new compound of a = 0.435 nm with rock salt structure. In this structure, Al and Nb atoms were distributed randomly in the cation sites. Anion sites were also randomly occupied by oxide and nitride ions with some amount of vacancy. The chemical composition was represented as Nb0.56Al0.44O0.38N0.37□0.25 from Rietveld refinement and oxygen/ nitrogen measurement. In the case of Ta, monoclinic Ta3N5 crystallized with a small amount of Ta4N5 impurity at x = 0.5. Aluminum compound was co-present as amorphous impurity.

Critical evaluation of the Aluminium–Tantalum–Titanium system

Experimental data published on the phase relationships in the Al–Ta–Ti system have been critically evaluated and a recommended set of internally consistent phase diagrams is given. The work is performed within the MSIT evaluation programs, partially published in the MSIT Phase Diagram Center and in the Landolt–Boernstein book series. The work is dedicated to the memory of Prof. Riccardo Ferro, a founding member of MSIT, Materials Science International Team.

Arc Evaporation of Ti–Al–Ta–N Coatings: The Effect of Bias Voltage and Ta on High-temperature Tribological Properties

Recently, titanium aluminium tantalum nitride (Ti–Al–Ta–N) coatings have been shown to exhibit beneficial properties for cutting applications. However, the reason for the improved behaviour of these coatings in comparison to unalloyed Ti–Al–N is not yet clear. Here, we report on the tribological mechanisms present in the temperature range between 25 and 900 °C for this coating system, and in particular on the effect of the bias voltage during deposition on the tribological response. Based on these results, we provide an explanation for the improved performance of Ta-alloyed coatings. An industrial-scale cathodic arc evaporation facility was used to deposit the coatings from powder metallurgically produced Ti40Al60 and Ti38Al57Ta5 targets at bias voltages ranging from −40 to −160 V. X-ray diffraction experiments displayed a change with increasing bias voltage from a dual-phase structure containing cubic and hexagonal phases to a single-phase cubic structure. Investigations of the wear behaviour at various temperatures showed different controlling effects in the respective temperature ranges. The results of dry sliding tests at room temperature were independent of bias voltage and Ta-alloying, where the atmosphere, i.e. moisture and oxygen, were the most important parameters during the test. At 500 °C, bias and droplet-generated surface roughness were identified to determine the tribological behaviour. At 700 and 900 °C, wear depended on the coating’s resistance to oxidation, which was also influenced by the bias voltage. In conclusion, Ta-alloyed coatings show a significantly higher resistance to oxidation than unalloyed Ti–Al–N which could be an important reason for the improved performance in cutting operations.