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All-inorganic perovskites, adopting cesium (Cs + ) cation to completely replace the organic component of A-sites of hybrid organic–inorganic halide perovskites, have attracted much attention owing to the excellent thermal stability. However, all-inorganic iodine-based perovskites generally exhibit poor phase stability in ambient conditions. Herein, we propose an efficient strategy to introduce antimony (Sb 3+ ) into the crystalline lattices of CsPbI 2 Br perovskite, which can effectively regulate the growth of perovskite crystals to obtain a more stable perovskite phase. Due to the much smaller ionic radius and lower electronegativity of trivalent Sb 3+ than those of Pb 2+ , the Sb 3+ doping can decrease surface defects and suppress charge recombination, resulting in longer carrier lifetime and negligible hysteresis. As a result, the all-inorganic perovskite solar cells (PSCs) based on 0.25% Sb 3+ doped CsPbI 2 Br light absorber and screen-printable nanocarbon counter electrode achieved a power conversion efficiency of 11.06%, which is 16% higher than that of the control devices without Sb 3+ doping. Moreover, the Sb 3+ doped all-inorganic PSCs also exhibited greatly improved endurance against heat and moisture. Due to the use of low-cost and easy-to-process nanocarbon counter electrodes, the manufacturing process of the all-inorganic PSCs is very convenient and highly repeatable, and the manufacturing cost can be greatly reduced. This work offers a promising approach to constructing high-stability all-inorganic PSCs by introducing appropriate lattice doping.

In ordered to understand the electronic structure, structural phase stability, magnetic properties, and Fermi surface studies of the 122 type of SrFe2X2, where (X = P, As, Sb) were investigated. For this purpose, the plane wave self-consistent method was used. Using the Brich–Murnaghan equation, their electronic structure and magnetic ordering were also investigated. It was understood that, under pressure, the compound SrFe2As2 undergoes a structural phase change from the tetragonal phase into the collapsed tetragonal phase. Further, due to their larger lattice constants, antimonides with larger local iron magnetic moment exhibit an enhanced Hund's rule coupling. Furthermore, smaller intra-atomic exchange coupling and significantly smaller lattice constants may be the cause of the extremely small local Fe moment for phosphates. The analysis of the valence charge density in the collapsed tetragonal phase demonstrates that the interactions between As atoms are more pronounced when compressed along the c-axis. The strength of this interaction is primarily governed by the Fe-As chemical bonding. The collapsed tetragonal phase of SrFe2As2 compounds, as observed in Fermi surface studies, indicates the absence of nesting of Fermi surfaces. It is clear that, from the studies, the tetragonal phase of Fermi surface nesting resulted in the long-range magnetic order, leading to the presence of superconductivity.

The current focus on the development of structural materials that can operate at temperatures beyond the current capability exposes materials to an extreme of enhanced oxidation attack. The emerging class of refractory multiple principal element alloys (RMPEA) offers superior structural performance at elevated temperature, but the alloys are susceptible to rapid oxidation. Alloy designs to enhance the oxidation resistance can compromise the structural performance, necessitating the application of environmental-resistant coatings. To provide environmental protection, a Mo-Si-B coating was successfully applied to RMPEA samples with the composition (Mo 95 W 5 ) 85 Ta 10 (TiZr) 5 through a two-step coating strategy to yield an outer aluminoborosilica scale with underlying silicide and boride phases, that are in equilibrium with the RMPEA and provide an effective oxidation resistance. At the same time, the long-term stability of an RMPEA must be considered, since sluggish diffusion at 1300°C, which is about one-half of the melting temperature, can delay the onset of precipitation reactions that can impact the structural performance. While silica-based coatings can provide an effective protection against oxidation at high temperature under an ambient atmosphere, other environments such as low oxygen pressures can prove to reduce the effectiveness and require coating modification for effective protection.

The phase stability, mechanical properties, and functional properties of Ti–5.5Al–11.8[Mo]eq alloys are focused on in this study by substituting 3d transition metal elements (V, Cr, Co, and Ni) for Mo as β-stabilizers to achieve similar β phase stability and room temperature (RT) superelasticity. The ternary alloy systems with the equivalent chemical compositions of Ti–5.5Al–17.7V, Ti–5.5Al–9.5Cr, Ti–5.5Al–7.0Co, and Ti–5.5Al–9.5Ni (mass%) alloys were selected as the target materials based on the Mo equivalent formula, which has been applied for the Ti–5.5Al–11.8Mo alloy in the literature. The fundamental mechanical properties and functionalities of the selected alloys were examined. The β phase was stabilized at RT in all alloys except for the Ti–Al–V alloy. Among all alloys, the Ti–Al–Ni alloy exhibited superelasticity in the cyclic loading–unloading tensile tests at RT. As a result, similar to the Ti–5.5Al–11.8Mo mother alloy, by utilizing the Mo equivalent formula to substitute 3d transition metal elements for Mo, a RT superelasticity was successfully imposed.

The ongoing electrification and miniaturization increase the quality demands on solder joints. A bottleneck for solder joint reliability can be the intermetallic Cu6Sn5 phase, which undergoes a phase transition, implying a volume change in a relevant temperature range. There are contradicting reports on the sign and magnitude of this volume change, which possibly implements stresses and cracks in solder joints. To clarify the characteristics of the phase transition, different samples were manufactured by applying industrial-like standards and isothermal heat treatments around the predicted phase transition temperature. Using x-ray diffraction, a coexistence of ordered η′ and disordered η was detected in samples treated at 438–445 K. The lattice parameters show that the volume of the disordered η phase is approximately 0.64–0.65% smaller than the one of the ordered η′ phase. A comparison with order–disorder transitions in structurally related phases shows that the volume change based on order–disorder transitions is normally of opposite sign and around 0.1–0.2%. Therefore, an effect of different compositions is considered responsible for the volume change. Adopting the exact composition Cu6Sn5 (Cu1.20Sn) for the η′ phase, it was estimated, based on density functional theory calculations from the literature, that the coexisting η phase assumes lower Cu content of Cu1.171Sn at 438 K and Cu1.174Sn at 445 K. In contrast, the lattice parameters of η′, generated at different temperatures, imply a largely temperature-independent composition of Cu1.20Sn. This leads to adjustments of the Cu-Sn phase diagram.

Purpose Conventional isolated dc–dc converters offer an efficient solution for performing voltage conversion with a large improved voltage gain. However, the small-signal analysis of these converters shows that a right-half-plane (RHP) zero appears in their control-to-output transfer function, exhibiting a nonminimum-phase stability. This RHP zero can limit the frequency response and dynamic specifications of the converters; therefore, the output voltage response is sluggish. To overcome these problems, the purpose of this study is to analyze, model and design a new isolated forward single-ended primary-inductor converter (IFSEPIC) through RHP zero alleviation. Design/methodology/approach At first, the normal operation of the suggested IFSEPIC is studied. Then, its average model and control-to-output transfer function are derived. Based on the obtained model and Routh–Hurwitz criterion, the components are suitably designed for the proposed IFSEPIC, such that the derived dynamic model can eliminate the RHP zero. Findings The advantages of the proposed IFSEPIC can be summarized as: This converter can provide conditions to achieve fast dynamic behavior and minimum-phase stability, owing to the RHP zero cancellation; with respect to conventional isolated converters, a larger gain can be realized using the proposed topology; thus, it is possible to attain a smaller operating duty cycle; for conventional isolated converters, transformer core saturation is a major concern, owing to a large magnetizing current. However, the average value of the magnetizing current becomes zero for the proposed IFSEPIC, thereby avoiding core saturation, particularly at high frequencies; and the input current of the proposed converter is continuous, reducing input current ripple. Originality/value The key benefits of the proposed IFSEPIC are shown via comparisons. To validate the design method and theoretical findings, a practical implementation is presented.

Using ab initio calculations, the phase stability of modulated and tetragonal martensitic structures in Ni 43.75 Co 6.25 Mn 43.75 (In, Sn) 6.25 Heusler alloys with different magnetic order is investigated. The stability against the segregation is considered by a method for generating all possible decay reactions assuming the calculated ground state energies of each composition. It is shown that the highest probable stability under equilibrium conditions is demonstrated by alloys with tetragonal martensitic structure in accordance with reactions: Ni 35 Co 5 Mn 35 In 5 → 25Mn + 35Ni + 5Mn 2 InCo and Ni 35 Co 5 Mn 35 Sn 5 → 5CoSn + 35Mn + 35Ni.

Electromigration damage due to void propagation in thin films has garnered much attention due to its implications for efficient design of interconnects. Voids can drift along the line, preserving its shape, or evolve into various time-dependent configurations, which are governed by the interplay between the capillarity and electron wind force. We have employed the phase-field method to elucidate the transition of a circular void to a finger-like slit. Following an initial transient regime, the void attains an equilibrium shape with a narrow parallel slit-like body, which contains a circular rear end, and a parabolic tip. The subsequent drift of the void is characterized by shape invariance along with a steady-state slit width and velocity, which scale with the applied electric field as \\[E^{-1/2}\\] and \\[E^{3/2}\\], respectively. The results obtained from phase-field simulations are critically compared with the sharp-interface solution. Repercussions of the study, in terms of prediction of void migration in flip-chip Sn-Ag-Cu solder bumps and fabrication of channels with desired micro/nanodimensions, are discussed.

In this paper, we developed models for 21 quinary high-entropy transition metal carbide ceramics (HETMCCs), composed of carbon and the transition metals Ti, Zr, Mo, V, Nb, W, and Ta, employing the Special Quasirandom Structures (SQS) method. We investigated how the transition metal elements influence lattice distortion, mixing enthalpy, Gibbs free energy of mixing, and the electronic structure of the systems through first-principles calculations. The calculations show that 21 systems can form a stable single phase, among which (TiMoVNbTa)C5, (ZrMoNbWTa)C5, and (MoVNbWTa)C5 exhibit superior stability. The formation energy and migration energy of carbon vacancies in systems with strong single-phase stability were calculated to predict their radiation resistance. The formation energy of carbon vacancies is closely related to the types of surrounding transition metal elements, with values ranging between the maximum and minimum formation energies observed in binary transition metal carbides (TMCs). The range of migration energy for carbon vacancies is wider than that observed in TMCs, which can hinder their long-range migration and enhance the radiation resistance of the materials.