The presence of amorphous oxide layers can significantly affect the coherent time of superconducting qubits due to their high dielectric loss. Typically, the surface oxides of superconductor films exhibit lossy and unstable behavior when exposed to air. To increase the coherence time, it is essential for qubits to have stable and low dielectric loss oxides, either as barrier or passivation layers. In this study, we highlight the robust and stable nature of an amorphous tantalum oxide layer formed on α-Ta (110) film by employing chemical and structural analyses. Such kind of oxide layer forms in a self-limiting process on the surface of α-Ta (110) film in piranha solution, yielding stable thickness and steady chemical composition. Quarter-wavelength coplanar waveguide resonators are made to study the loss of this oxide. One resonator has a Qi of 3.0 × 106 in the single photon region. The Qi of most devices are higher than 2.0 × 106. Moreover, most of them are still over 1 × 106 even after exposed to air for months. Based on these findings, we propose an all-tantalum superconducting qubit utilizing such oxide as passivation layers, which possess low dielectric loss and improved stability.

This study delivers a comprehensive evaluation of tantalum-based coatings designed as protective surface layers for cardiovascular stents, focusing on their mechanical durability, corrosion resistance, and surface properties relevant to hemocompatibility. Coatings consisting of tantalum (Ta), tantalum oxide (Ta2O5), and a bilayer Ta/Ta2O5 system were deposited onto 316L stainless steel using plasma-assisted reactive magnetron sputtering. Structural characterization confirmed a nanocrystalline β-phase for Ta, while Ta2O5 exhibited an amorphous, dense, grain-boundary-free morphology that provided superior crack resistance together with enhanced corrosion protection. The bilayer configuration demonstrated the highest overall performance by combining the hardness and mechanical support of Ta with the chemical inertness and stability of Ta2O5. This architecture achieved the greatest hardness (861.5 HV), improved toughness proxies expressed as H/E = 0.08 and H3/E2 = 0.06 GPa, and a favorable modulus gradient that effectively reduced interfacial stress and increased adhesion. Electrochemical testing in Hanks’ Body Fluid showed a dramatic 1000-fold reduction in corrosion current when compared with uncoated stainless steel, surpassing the performance of both individual monolayers. Assessments of surface properties further demonstrated that hydrophilic, oxide-rich surfaces limited protein adsorption and platelet activation, with Ta2O5 and Ta/Ta2O5 coatings performing strongly. Overall, these findings indicate that Ta/Ta2O5 bilayers provide a multifunctional surface solution for next-generation stents.

The ability to passivate metallic surfaces under non-UHV conditions is not only of fundamental interests, but also of growing practical importance in catalysis and microelectronics. In this work, the passivation effect of a surface iodine layer on air-exposed Ta for the copper electroless deposition was investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Although the passivation effect was seriously weakened by the prolonged air exposure, iodine passivates the Ta substrate under brief air exposure conditions so that enhanced copper wetting and adhesion are observed on I-passivated Ta relative to the untreated surface.

Tantalum-cased tantalum capacitors were tested with regard to temperature stability, capacitance ratio, surge current capabilities, shock, vibration, and thermal shock. They were found to be superior to the conventional wet slug tantalum capacitor cased in silver, since they are more resistant to sulfuric acid. The tantalum-cased tantalum capacitors are widely accepted for use in critical electronic equipment because of their excellent performance and reliability.

A detailed literature search was carried out to define the current knowledge about the biological performance of tantalum. The pure metal appears, to a great degree, to be inert both in vivo and in vitro. Both the pure metal and its principle oxide possess low solubility and toxicity; however, halide compounds are more biologically active. Local host response is benign, characterized by vital encapsulation in soft tissue and frequent osteointegration, reminiscent of titanium, in hard tissue. Tantalum has been in clinical use since before 1940 and has found a wide range of diagnostic and implant applications, with apparently overall excellent results. In some applications, such as for radiographic bone markers and cranial closure, tantalum may well be the current material of choice. In summary, metallic tantalum is a promising biomaterial whose applications have been limited by technical rather than biological performance considerations.