High-entropy alloys (HEAs) contain more than five alloying elements in a composition range of 5–35% and with slight atomic size variation. Recent narrative studies on HEA thin films and their synthesis through deposition techniques such as sputtering have highlighted the need for determining the corrosion behaviors of such alloys used as biomaterials, for example, in implants. Coatings composed of biocompatible elements such as titanium, cobalt, chrome, nickel, and molybdenum at the nominal composition of Co₃₀Cr₂₀Ni₂₀Mo₂₀Ti₁₀ were synthesized by means of high-vacuum radiofrequency magnetron (HVRF) sputtering. In scanning electron microscopy (SEM) analysis, the coating samples deposited with higher ion densities were thicker than those deposited with lower ion densities (thin films). The X-ray diffraction (XRD) results of the thin films heat treated at higher temperatures, i.e., 600 and 800 °C, revealed a low degree of crystallinity. In thicker coatings and samples without heat treatment, the XRD peaks were amorphous. The samples coated at lower ion densities, i.e., 20 µAcm⁻², and not subjected to heat treatment yielded superior results in terms of corrosion and biocompatibility among all the samples. Heat treatment at higher temperatures led to alloy oxidation, thus compromising the corrosion property of the deposited coatings.

The thermodynamic stability of λ-Ti ₃ O ₅ is enhanced by reducing crystallite size, enabling size-based tuning of heat-storage properties.

Controlling the phase composition of copper sulfide (CuxSy) semiconductors during synthesis is a critical yet underexplored challenge in heterostructure engineering. In this study, a sequential hot-injection strategy was developed to enable phase-selective synthesis of CuxSy nanostructures (Cu7S4, Cu2S, and CuS) through systematic variation of Cu:S precursor stoichiometry, allowing precise tuning of phase-dependent electronic properties. Comparative photoelectrochemical evaluation under simulated solar irradiation identifies CuS as the most photoactive phase, attributed to its favorable band structure ( Eg ≈ 2.3 eV) and superior charge-separation behavior. Building on this phase selection, CuS was interfacially integrated with narrow-bandgap spinel MnFe2O4 (Eg ≈ 1.5 eV) to construct MnFe2O4-CuS heterostructures with controlled interfacial contact, enabling efficient interfacial charge transfer. Structural characterization confirms phase coexistence without bulk transformation, while optical and electrochemical analyses reveal substantially improved carrier dynamics, including suppressed photoluminescence emission, enhanced transient photocurrent density, and reduced charge-transfer resistance in Nyquist impedance plots. The optimized 1:1 heterostructure (MFCS-1) achieves ∼99.7% pollutant degradation with a pseudo-first-order rate constant k_"app" ≈ 0.045 min-1, along with good operational stability over five consecutive cycles. This enhanced performance is attributed to synergistic effects between phase-engineered CuS and efficient heterointerface charge transfer. These findings demonstrate that sequential hot-injection enabled phase regulation combined with rational heterointerface construction provides an effective strategy for tailoring the electronic properties of Cu-based semiconductor heterostructures.