Substitutional Elements Research Articles

(Invited) New Class of Plasmonic Alloy Nanoparticles

The past 150 years of research on inorganic nanomaterials that exhibit intrinsic localized surface plasmon resonance (LSPR) in the visible region has focused on well-disperse nanoparticles (NPs) composed of coinage metals (Au, Ag, and Cu). Recent theoretical studies on photo-excited electron dynamics in Au NPs have revealed that not only the interband transition but also the screening caused by the vibrations of bound electrons by visible light are important for visible LSPR [1]. However, the correlation between the electronic and crystal structure (as a means to control the screening effect) remains unclear because most alloys based on coinage metals have a face-centred cubic (fcc)-based structure. Here, we show that well-disperse pseudospherical intermetallic Pd-based alloy NPs with a B2 structure and PtIn2 NPs with a C1 (CaF2-type) structure intrinsically exhibit LSPR absorption in the visible region.It is well known that chemical conversion of inorganic NPs via element substitution reactions, such as ion exchange reactions [2] and galvanic replacement reactions, can overcome the difficulties associated with controlling the size, shape, chemical composition, and crystal structure in conventional syntheses [3-5]. Especially, alloying enables us to drastically modulate the electronic properties of metallic NPs. The retained shape of the parent-NPs in element replacement reactions provides an opportunity to obtain non-equilibrium unique structures and even new structures of inorganic NPs. We demonstrate that various Pd-based alloy NPs with a B2 structure were synthesized by the element replacement reactions with Pd–P NPs and showed LSPR in the visible region [6]. This is an alchemy in nanoplasmonics in the sense that the plasmonic properties of group 11 elements are reproduced by using non-group 11 elements. On the other hand, we successfully synthesized pseudospherical PtIn2 intermetallic NPs with a C1 structure as uncommon types of visible plasmonic NPs [7].Simulations of above alloy NPs and fcc-Au NPs indicate that both the reduction in the interband transition and the strong screening by a small number of bound d-electrons are the main origins of the visible plasmonic features of alloy NPs. Our results demonstrate that the composition and crystal structure of the intermetallic NPs of our work determine the interband transition and the screening effect. Our findings dramatically expand the plasmonic NP library and highlight remarkable NPs that are far superior, in terms of physical and chemical properties, to conventional plasmonic NPs.[1] Iida, K.; Noda, M.; Ishihara, K.; Nobusada, K. J. Phys. Chem. A 2014, 118, 11317–11322.[2] Saruyama, M.; Sato, R.; Teranishi, T. Acc. Chem. Res. 2021, 54, 765–775.[3] Wu, H.-L.; Sato, R.; Teranishi, T. et al., Science 2016, 351, 1306–1310.[4] Li, Z.; Saruyama, M.; Asaka, T.; Tatetsu, Y.; Teranishi, T. Science 2021, 373, 332–337.[5] Matsumoto, K.; Sato, R.; Tatetsu, Y.; Teranishi, T. et al., Nat. Commun. 2022, 13, 1047.[6] Sato, R.; Takekuma, H.; Teranishi T. et al., to be submitted.[7] Takekuma, H.; Sato, R.; Iida, K.; Teranishi, T. et al., submitted.

Influence of A/B Element Substitution on Negative Thermal Expansion in AB(CN)6 (A = Al, Ga, In; B = Co, Fe, Mn, Cr, V, Ti): A Density Functional Theory Study.

Negative thermal expansion as an abnormal physical behavior of materials has promising applications in a high sophisticated equipment field, but the materials are rare. Here, we use the first-principles calculations based on density functional theory combined with the recently developed average atomic volume (AAV = V/N, where V is unit cell volume and N is the number of atoms in the unit) rule to predict the large isotropic negative thermal expansion materials of Prussian blue analogues AB(CN)6 (A = Al, Ga, In; B = Co, Fe, Mn, Cr, V, Ti) in a wide temperature range. Our results clearly show that the coefficient of negative thermal expansion has a near-linear relationship with the average atomic volume of the systems and is also influenced by the element substitution at the A or B site. Lattice dynamic simulations indicate that the main contribution to the negative thermal expansion comes from the low-frequency transverse vibration of the (B)-C≡N-(A) groups, especially the transverse vibration of the N atoms. Thus, the element substitution at the A site (binding to N) can tune the negative thermal expansion behavior of the systems more effectively than that at the B site (binding to C), indicating the different roles of bonds on the negative thermal expansion. Our present work not only expands the kinds of isotropic materials but also gives some insights into the relationship between the average atomic volume and negative thermal expansion.

Development of cobalt (Co)-doped monetites for bone regeneration.

Cobalt-doped monetite powders were synthesized by coprecipitation method under a cobalt nominal content between 2 and 20 mol % of total cation. Structural characterization of samples was performed by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. XRD results indicated that the Co-doped samples exhibited a monetite single-phase with the cell parameters and crystallite size dependent on the amount of substitutional element incorporated into the triclinic crystalline structure. Cell viability and adhesion assays using pre-osteoblastic cells showed there is no toxicity and the RTqPCR analysis showed significant differences in the expression for osteoblastic phenotype genes, showing a potential material for the bone regeneration.

The role of nonmetallic ion substitution in perovskite LaCoO3 for improved oxygen evolution reaction activity

Transition metal perovskite (ABO3) is an emerging type of oxygen evolution reaction (OER) electrocatalyst that shows reasonably good activity and moderate stability. Although efforts have been made to improve perovskite’ OER performance by various element substitution at A/B-site, the influence of ion, particularly non-metallic ion, substitutions on the OER mechanism are rarely studied. More and more evidence has shown that the metal-center theory has failed to explain lots of OER-related phenomena. Therefore, it is urgent to understand how the cation and anion sites in perovskite determine OER performance. Here, we used a Fe and P co-doped LaCoO3 as a model system to explore the influence of substitution in perovskite by combinng operando/ex-situ X-ray characterization and density functional theroy (DFT). We observed enhanced OER catalytic activities in co-doped materials, which are attributed to the stronger transition-metal-oxygen-bonding-covalency (TMOBC). The detailed analyses by O K-edge XAS, electrochemical performance, and DFT suggest that the hybridization between O 2p and transition metal 3d eg orbitals could be a more credible descriptor of perovskite for OER, which is the combination of eg orbital theory and TMOBC theory. The finding in our work provides insights into the OER catalysis mechanism on metal oxides, which could guide new design of cost-effective oxide electrocatalysts.

Nature of fluid and genetic affiliation of the Bakoshi-Kundila Au deposit, Nigeria: Evidence from trace elements in hydrothermal quartz

The Bakoshi-Kundila Au deposit is located in the Nigerian Shield in West Africa. In this deposit, Au-bearing pyrite contains inclusions of Au-rich hydrothermal quartz. Whether or not this co-precipitation relationship of quartz and pyrite is cogenetic and related to the gold fluid remains untested. The deposit's genetic affiliation is controversial. This study reports the results of textural and in situ chemical compositions of hydrothermal quartz, and sheds light on fluid composition, element substitutions into quartz structure, and inferred the deposit genetic type. We grouped the quartz into four generations: Qz1 and Qz2 (vein-type) and Qz3 and Qz4 (wallrock-type). The Qz2 is deformed, overprinted by late-stage fluid activity. The Qz1 is rich in Ga and Sr but poor in Al and Fe than Qz3 and Qz4: average Ga in ppm (Qz1 – 0.62, Qz3 – 0.08, Qz4 – 0.15), Sr (Qz1– 26.7, Qz3 – 4.59, Qz4 – 5.78), Al (Qz1– 16.7, Qz3 – 82.8, Qz4 – 136), Fe (Qz1– 131, Qz3 – 144, Qz4 – 133). However, the contents of low melting point chalcophile elements (LMCE) are higher and overlapped between Qz1 and Qz3 than those from Qz4: average Au in ppm (Qz1– 33.9, Qz3 – 38.2, Qz4 – 7.83), Cu (Qz1 – 13.1, Qz3 – 14.8, Qz4 – 5.95), Bi (Qz1 – 3.48, Qz3 – 0.25, Qz4 – 0.51). The LMCE in Qz1 displayed covariant relationships with Au (but poorly defined in Qz3 and Qz4), suggesting the likely presence of Au-Ag-(±Te)-bearing phases like petzite and argentum. Aluminum is the main trivalent element substituting Si4+ in Q3 and Qz4, whereas Fe3+ in Qz1. The charge-balanced cations are Li+, Na+, and K+ in Qz3 and Qz4, whereas Sr2+ in Qz1. The Al and Ti contents (in ppm) are higher and more variable in Qz3 (Al: 5.97–374, avg 82.8; Ti: 2.69–12.5, avg 6.60) and Qz4 (Al: 8.13–792, avg 136; Ti: 7.64–72.0, avg 20.2), which may imply fluctuation in fluid pH. These element concentrations are lower and less variable in Qz1 (Al: 5.25–47.8, avg 16.7; Ti: 3.41–18.0, avg 5.43), suggesting a less acidic and probably stable pH condition during its precipitation. The Qz1 has a lower average content (in ppm) of compatible elements (K – 15.7, Fe – 13.1, Ti – 5.43) than Qz3 (K – 25.9, Fe – 144, Ti – 6.60) and Qz4 (K – 63.0 Fe – 133, Ti – 20.2), implying that Qz3 and Qz4 precipitated at a higher temperature than Qz1. However, the contents of the incompatible elements (e.g., P, Ge, Rb, and Li) are not enriched in the supposed lately-formed Qz1 over Qz3 and Qz4, which is inconsistent. The inconsistency is also true between the wallrock type, with lower contents in low-temperature Qz3 than in high-temperature Qz4. Thus, temperature is considered not a major controlling factor during the formation of Bakoshi-Kundila quartz; instead, the pH condition and fluid-rock reaction are favored. The Bakoshi-Kundila quartz has Al-Ti contents akin to quartz from orogenic Au deposits.

Aliovalent dual element co-assisted strategy to enhance ionic conductivity and stability of NASICON-type solid electrolyte for all-solid-state sodium batteries

The urgent need for high-performance sodium batteries has drawn great attention to the development of novel solid-state electrolyte systems. However, it is still a great challenge to obtain excellent ionic conductivity and interfacial stability performance for most solid-state electrolytes. In this study, a new NASICON-type solid-state electrolyte Na3.1+xZr2−xScxSi2.1P0.9O12 (donated as NZSSP, x = 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3) was successfully prepared by solid-phase method. Due to the aliovalent substitution of Sc3+/Si4+, the phase transition or unwanted rhombohedral phase is effectively suppressed, the Na+ transport channel bottlenecks are greatly enlarged, and the concentration of Na+ is largely increased, giving rise to the significant improvement of the ionic conductivity and stability of NZSSP solid-state electrolyte. The Na3.35Zr1.75Sc0.25Si2.1P0.9O12 solid-state electrolyte has an ultra-high ionic conductivity of 4.92 mS cm−1 at room temperature. Meanwhile, it shows an excellent sodium plating/stripping stability by the optimization of the Na+ transport channel. The critical current density of the Na//Na3.35Zr1.75Sc0.25Si2.1P0.9O12//Na symmetric battery is achieved up to 1.0 mA cm−2, and it can stably cycle for nearly 3000 h at 0.1 mA cm−2 or 1000 h at 0.5 mA cm−2 at room temperature. A detailed analysis of these aliovalent dual element substitution samples has been performed, and the mechanism of the conductivity enhancement is discussed systematically. This study can provide a feasible method to improve the ionic conductivity and electrochemical stability of NZSP materials and paves a way for the application of all-solid-state sodium batteries.

Solid solution softening or hardening induced by minor substitutional additions in a Hf20Nb31Ta31Ti18 refractory high entropy alloy

The effect of minor additions of substitutional elements such as Al, Cu, Mn, and Fe on the room-temperature (RT) and elevated-temperature hardness of a single bcc phase Hf20Nb31Ta31Ti18 refractory high entropy alloy is studied here. Interestingly, 2.5 at. % nominal addition of Fe hardened the base Hf20Nb31Ta31Ti18 alloy in the temperature range from RT to 800 °C, while the same nominal content of addition of Al, Cu, and Mn softened the base alloy from RT to 1000 °C. Regardless of solid solution hardening or solid solution softening, the hardness variation with temperature essentially showed the same three-stage pattern for all studied alloys here: a temperature-dependent decrease in hardness below 300 °C/400 °C, followed by a temperature-independent hardness plateau between 300/400 and 800 °C, and finally a temperature-dependent decrease in hardness at temperatures higher than 800 °C. The mechanism for solid solution hardening or softening in bcc-structured refractory high entropy alloys is discussed, together with their temperature dependence.

A method for converting the existing mechanical zoom optical system to the focus tunable lens zoom optical system

The focus tunable lens (FTL), an emerging device, has brought a new development direction for the research of zoom optical systems, and the zoom lens designed with this lens has more advantages in response speed and mechanical vibration control than the conventional mechanical zoom system. However, there is a relative lack of design methods and computational theories for this type of system at present, and there is a lack of initial structure patents for reference. To solve this problem, this paper proposes a method that can convert the existing conventional mechanical zoom system into an FTL zoom system, and we first introduce the equivalent group element substitution theory for optical systems, then we design a computational screening algorithm for the equivalent FTL group element. We performed an example demonstration to illustrate the details of this method, and we finally obtain one FTL zoom optical system with an F/# of 4, a total length of 120 mm, and an 8 mm image plane. The whole design process is smooth, and the system structure is stable.

Acculturation of Islamic Law and Local Culture in Marriage Customs of the Buol People: An Anthropological Perspective

The objective of this study is to examine acculturation of Islamic Law and Local culture in the Marriage Customs of the Buol People: This study examined two problems. First, how is the process of acculturation? Second, what acculturation occurs between Islamic law and local culture in the marriage customs of the Buol people?. This study used qualitative method with an empirical sociological legal research analysis approach. Data was gathered through in-depth interviews, direct observation, and participant observation, and physical equipment. The results of the study show that the process of acculturation occurs through power or politics, through trade, education, or da'wah and the arts, as well as through marriage and migration. Acculturation also occurs at every stage of the implementation of marriage customs among the Buol people, including through Mongolyokap, Molyako nikah or marraige proposal, Motanduan moposakis or determination and witnesses, Mopake bolre or decorating the bride's house, Mogundud nikah or delivering the requested property, Moponika or reading of Ijab Qabul (Islamic marriage contract), Monobvuwunggag or invalidating wudhu, Mongoliayondigi, Mopoalyom/Mogolya mongaano or wedding reception, Mosalyamat or small post-wedding party, and Mogolya mopolyong or sleeping at the groom's house. The forms of acculturation are substitution or addition of cultural elements, syncretism or an amalgamation of cultural factors, addition or combination of cultural elements, and deculturation or replacement of cultural aspects.

Two-Dimensional Planar Penta-NiPN with Ultrahigh Carrier Mobility and Its Potential Application in NO and NO2 Gas Sensing.

Two-dimensional (2D) materials with novel structures and electronic properties are promising candidates for the next generation of micro- and nano-electronic devices. Herein, inspired by the recent experimental synthesis of penta-NiN2 (ACS Nano, 2021, 15, 13539-13546), we propose for the first time a novel ternary penta-NiPN monolayer with high stability by partial element substitution. Our predicted penta-NiPN monolayer is a quasi-direct bandgap (1.237 eV) semiconductor with ultrahigh carrier mobilities (103-105 cm2V-1s-1). Furthermore, we systematically studied the adsorption properties of common gas molecules (CO, CO2, CH4, H2, H2O, H2S, N2, NO, NO2, NH3, and SO2) on the penta-NiPN monolayer and its effects on electronic properties. According to the energetic, geometric, and electronic analyses, the penta-NiPN monolayer is predicted to be a promising candidate for NO and NO2 molecules. The excellent electronic properties of and the unique selectivity of the penta-NiPN monolayer for NO and NO2 adsorption suggest that it has high potential in advanced electronics and gas sensing applications.

Halide double-perovskites: High efficient light emission and beyond

Lead-free halide double perovskites are stable and versatile materials for a wide range of applications, particularly for lighting, thanks to their very efficient emission of warm white light. Element substitution in halide double perovskite is recognized as a powerful method for tuning the emission wavelength and improve the efficiency. This review provides an overview on composition and recent progress in halide double perovskite with main focus on the synthesis and emission properties of chloride-based compounds.

Influence of element substitutions on poisoning behavior of ZrV2 alloy: theoretical and experimental investigations

Influence of element substitutions on poisoning behavior of ZrV2 alloy: theoretical and experimental investigations

Magnetic properties of SmMn1-xCoxO3 and Sm1-yRyMn0.6Co0.4O3

Polycrystalline SmMn1-xCoxO3 and Sm1-yRyMn0.6Co0.4O3, which have a single orthorhombic perovskite-type structure without any impurities, were prepared by complex polymerization to investigate the effects of A- and B-site element substitutions on the crystal structure and magnetic properties. The unit-cell volume of SmMn1-xCoxO3 decreased with increasing x and that of Sm1-yRyMn0.6Co0.4O3 increased with increasing average radius of A-site ions ⟨rR⟩, and the chemical pressure due to element substitution was observed in these two systems. At 0.0 ≤ x ≤ 0.4 in SmMn1-xCoxO3, a marked increase in the field-cooled magnetization MFC and an increase in the canted-antiferromagnetic transition temperature Tc were observed with increasing x, but they decreased for 0.5 ≤ x ≤ 1.0. However, no specific spin reversal phenomenon was observed, unlike in other RMnO3 compounds. The magnetic susceptibility of both compounds obeyed the Curie–Weiss law with constant susceptibility above 200 K, which was not common in other Sm compounds, and the effective magnetic moment Peff could be easily evaluated. By analyzing Peff of SmMn1-xCoxO3, we determined the electronic states of the ions constituting the sample as Mn3+(high spin, HS), Mn4+, and Co2+(HS) at 0 < x ≤ 0.5 and Mn4+, Co3+(low spin), and Co2+(HS) at 0.5 < x ≤ 0.9. The MFC of Sm1-yRyMn0.6Co0.4O3 decreased with increasing Y and Lu concentrations and increased with La concentration. The Tc and Weiss temperature of Sm1-yRyMn0.6Co0.4O3, both of which increased linearly with increasing ⟨rR⟩, could be attributed to the effects of chemical pressure. Although M − H measurements showed that Sm3+ in Sm1-yRyMn0.6Co0.4O3 was paramagnetic, the Peff analysis results suggested that the excited state of Sm3+ was affected.

Anion Exchange of Metal Particles on Carbon-Based Skeletons for Promoting Dielectric Equilibrium and High-Efficiency Electromagnetic Wave Absorption.

The combination of carbon materials and magnetic elements is considered as an effective strategy to obtain high-performance electromagnetic wave (EMW) absorption materials. However, using nanoscale regulation to the optimization of composite material dielectric properties and enhanced magnetic loss properties is facing significant challenges. Here, the dielectric constant and magnetic loss capability of the carbon skeleton loaded with Cr compound particles are further tuned to enhance the EMW absorption performance. After 700 °C thermal resuscitation of the Cr3-polyvinyl pyrrolidone composite material, the chromium compound is represented as a needle-shaped structure of nanoparticles, which is fixed on the carbon skeleton derived from the polymer. The size-optimized CrN@PC composites are obtained after the substitution of more electronegative nitrogen elements using an anion-exchange strategy. The minimum reflection loss value of the composite is -105.9dB at a CrN particle size of 5nm, and the effective absorption bandwidth is 7.68GHz (complete Ku-band coverage) at 3.0mm. This work overcomes the limitations of impedance matching imbalance and magnetic loss deficiency in carbon-based materials through size tuning, and opens a new way to obtain carbon-based composites with ultra-high attenuation capability.

Thermal history of the Peel Plateau, northern Canadian Cordillera, resolved through multikinetic apatite fission-track dating

The Peel Plateau of the northern Canadian Cordillera has undergone multiple burial and unroofing events throughout the Phanerozoic, including subsidence and uplift associated with emergence of the Mackenzie Mountains. Episodic unroofing events are evinced by unconformities that represent a period where an unknown amount of material was deposited and eroded. Thermochronological studies have been conducted in neighboring physiographic regions, however no work has been conducted in the Peel Plateau and there is interest to determine whether it shares a similar thermal evolution as the surrounding regions. Apatite fission-track thermochronology (AFT) is a useful method for reconstructing basinal thermal histories as the system is sensitive to upper crustal temperatures, although the kinetics of the thermochronometer are complicated by numerous elemental substitutions within apatite that are known to control the specific temperature window within which fission-tracks anneal. This study uses three strategically positioned AFT samples from Phanerozoic sedimentary rocks to investigate the thermal history of the region from the Devonian to the present. Pooled AFT ages from all samples fail the χ2 test, implying there is a high level of intra-sample age dispersion and potentially indicating the samples contain multiple age populations. To assess whether the data are consistent with multiple kinetic AFT populations, we use grain-specific apatite compositions to derive rmro, a kinetic parameter that accounts for elemental substitutions known to control annealing kinetics of fission-tracks. By plotting AFT ages and track lengths against rmro we identify more-retentive and less-retentive apatite populations within each sample, which serve as independent thermochronometers when incorporated into inverse thermal history modelling. Results from a thermal history model of the Upper Devonian Imperial Formation indicate that the uppermost Paleozoic strata in the Peel Plateau reached maximum burial temperatures (∼165°C–185 °C) in the Triassic and were reheated to lower temperatures (∼90°C–100 °C) under a Cretaceous-Paleocene foreland basin. The temperature regime of the latter burial event is supported by thermal history models of two Cretaceous samples that record peak burial temperatures (∼80°C–90 °C) in the Paleocene to Eocene. This study highlights the capabilities of thermal history modelling from multikinetic AFT data and serves as a reminder that addressing variable annealing kinetics of apatite grains can improve the resolution of thermal models and the associated geologic interpretations.

Understanding Lithium-Ion Transport in Selenophosphate-Based Lithium Argyrodites and Their Limitations in Solid-State Batteries

To develop solid-state batteries with high power and energy densities, solid electrolytes with fast Li+ transport are required. Superionic lithium argyrodites have proven to be a versatile system, in which superior ionic conductivities can be achieved by elemental substitutions. Herein, we report the novel selenophosphate-based lithium argyrodites Li6–xPSe5–xBr1+x (0 ≤ x ≤ 0.2) exhibiting ionic conductivities up to 8.5 mS·cm–1 and uncover the origin of their fast Li+ transport. Rietveld refinement of neutron powder diffraction data reveals a better interconnection of the Li+ cages compared to the thiophosphate analogue Li6PS5Br, by the occupation of two additional Li+ sites, facilitating fast Li+ transport. Additionally, a larger unit cell volume, lattice softening, and higher structural disorder between halide and chalcogenide are unveiled. The application of Li5.85PSe4.85Br1.15 as the catholyte in In/LiIn|Li6PS5Br|LiNi0.83Co0.11Mn0.06O2:Li5.85PSe4.85Br1.15 solid-state batteries leads to severe degradation upon charging of the cell, revealing that selenophosphate-based lithium argyrodites are not suitable for applications in lithium nickel cobalt manganese oxide-based solid-state batteries from a performance perspective. This work further expands on the understanding of the structure–transport relationship in Li+ conducting argyrodites and re-emphasizes the necessity to consider chemical and electrochemical stability of solid electrolytes against the active materials when developing fast Li+ conductors.

Band gap predictions of double perovskite oxides using machine learning

The compositional and structural variety inherent to oxide perovskites spawn wide-ranging applications. In perovskites, the band gap Eg, a key material parameter for these applications, can be optimally controlled by varying the composition. Here, we implement a hierarchical screening process in which two cross-validated and predictive machine learning models for band gap classification and regression, trained using exhaustive datasets that span 68 elements of the periodic table, are applied sequentially. The classification model separates wide band gap materials, with Eg ≥ 0.5 eV, from materials which have zero or relatively small band gaps, namely Eg < 0.5 eV, and the second regression model quantitatively predicts the gap value of the wide band gap compounds. The study down-selects 13,589 cubic oxide perovskite compositions that are predicted to be experimentally formable, thermodynamically stable, and have a wide band gap. Of these, a subset of 310 compounds, which are predicted to be stable and formable with a confidence greater than 90%, are identified for further investigation. Our models are methodically analyzed via performance metrics and inter-dependence of model features to gain physical insight into the band gap prediction problem. Design maps to identify the variation of band gap with substitution of different elements are also presented.

Violet Antimony Phosphorus with Enhanced Photocatalytic Hydrogen Evolution.

Violet phosphorus (VP), a recently confirmed layered elemental structure, is demonstrated to have unique photoelectric, mechanical, and photocatalytic properties. Element substitution plays a significant role in modifying the physical/chemical properties of semiconducting materials. Herein, antimony is adopted to substitute some phosphorus atoms in VP crystals to tune their physical and chemical properties, resulting in a significantly enhanced photocatalytic hydrogen evolution performance. The antimony-substituted violet phosphorus single crystal (VP-Sb) is synthesized and characterized by single crystal X-ray diffraction (CSD-2214937). The bandgap of VP-Sb has been found to be lowered from that of VP by UV/vis diffuse reflectance spectroscopy and density-functional theory (DFT) calculation, enhancing the optical absorption during photocatalytic reaction. The conducting band minimum of VP-Sb is found to be upshifted from that of VP from measurements and calculation, enhancing its hydrogen reduction activity. The valance band maximum is found to be lowered to weaken its oxidation activity. The edge of VP-Sb is calculated to have an excellent H* adsorption-desorption performance and superior H2 generation kinetics. The H2 evolution rate of VP-Sb is demonstrated to be significantly enhanced to be 1473 µmol h-1 g-1 , about five times of that of pristine VP(299µmol h-1 g-1 ) under the same experimental conditions.

Microstructure and Texture Evolution of the Magnesium Alloy ZMX210 during Rolling and Annealing.

The processability during massive deformation of magnesium-wrought products is hampered by the low formability of magnesium alloys. The research results of recent years demonstrate that rare earth elements as alloying elements improve the properties of magnesium sheets, such as formability, strength and corrosion resistance. The substitution of rare earth elements by Ca in Mg-Zn-based alloys results in a similar texture evolution and mechanical behaviour as RE-containing alloys. This work is an approach to understanding the influence of Mn as an alloying element to increase the strength of a Mg-Zn-Ca alloy. For this aim, a Mg-Zn-Mn-Ca alloy is used to investigate how Mn affects the process parameters during rolling and the subsequent heat treatment. The microstructure, texture and mechanical properties of rolled sheets and heat treatment at different temperatures are compared. The outcome of casting and the thermo-mechanical treatment are used to discuss how to adapt the mechanical properties of magnesium alloy ZMX210. The alloy ZMX210 behaves very similarly to the ternary Mg-Zn-Ca alloys. The influence of the process parameter rolling temperature on the properties of the ZMX210 sheets was investigated. The rolling experiments show that the ZMX210 alloy has a relatively narrow process window.

Expanding the Absorption of Double Perovskite Cs2AgBiBr6 to NIR Region.

The toxicity of lead-based halide perovskites hampers broad application in optoelectronics. The lead-free perovskite Cs2AgBiBr6 is considered a promising candidate, owing to its long carrier lifetime and outstanding stability. However, the relatively large bandgap hinders its absorption in the visible region and thus the application of its photoelectric properties in the visible and near-infrared (NIR) regions. Therefore, the expansion of absorption to the longer wavelengths, even the NIR region, makes sense for solar cells and photodetector applications. Facile elemental doping or substitution of Cs2AgBiBr6 makes it potentially desirable for applications in both visible and NIR regions. As a result, band-edge adjustment to expand the absorption onset or trace deep-energy-level doping with a new intermediate band was achieved. Here, we summarize the elemental doping results and review the potential application of Cs2AgBiBr6 from these two aspects and give constructive perspectives for further development of lead-free perovskite.