Pb Substitution Research Articles

Upcycling of Pb from lead smelting residues to lead halide perovskite for piezocatalytic hydrogen production

Organic lead halide perovskite is a promising piezocatalyst for piezocatalytic H2 production, meanwhile, large amount of unutilized lead resources in lead smelting residues have caused ecological security and resource waste problems. Here, we report an efficient Pb upcycling approach to recover lead halides from lead smelting residues to create lead halide perovskites (r-FAPbBr3-xIx), distinguished by the remarkable piezoelectric properties, for piezocatalytic H2 evolution. Zinc impurities, concurrently from these residues, found their utilization in the partial substitution of Pb2+ within the halide octahedra of r-FAPbBr3-xIx. The intervention of zinc enhancing desorption of hydrogen from r-FAPbBr3-xIx and culminating in a pronounced H2 yield as 157.80 μmol·g−1·h−1. Notably, the used r-FAPbBr3-xIx that lost its functional prowess could be regenerated and exhibited a piezocatalytic capacity similar to its initial state, perpetuating a sustainable cycle of utility. This pioneering route to Pb upcycling furnishes an alternative avenue for the preparation and utilization of lead-based perovskites.

Effect of partial cation substitution on optoelectronic properties and ion diffusion behavior of inorganic lead halide perovskite: A theoretical investigation

Cation substitution is a widely utilized approach for tailoring the properties of lead halide perovskites. A comprehensive understanding of the impact of various cation substitutions on optoelectronic properties and ion diffusion behavior is crucial for enhancing the performance of halide perovskite materials. In this study, we constructed various double halide perovskites by cation substitution and investigated their optoelectronic properties and ion diffusion behavior through first-principles calculations. Our findings reveal that the A-site substitution with alkali cation Rb does not significantly influence the optoelectronic properties of lead halide perovskites. However, it will boost the halide migration due to the enlarged migration bottleneck. The B-site substitution with alkali earth element Sr significantly suppresses the halide migration; while the material will be no longer suitable for visible light absorption due to the enlarged bandgap. The substitution of Pb with d-orbital fulfilled Zn can also suppress the halide migration, but it will give rise to an indirect bandgap and hence affect the optoelectronic performance. The substitution of Pb with Sn can enhance both the thermostability and optoelectronic performance owing to the smaller ionic radius and similar ns2-containing electronic configuration. The increased migration barrier indicates that ion diffusion is also inhibited in double perovskite Cs2SnPbI6. Our results imply that the optoelectronic properties can be further optimized by tuning the ratio of Sn/Pb or the thickness of the perovskite layer in photovoltaic device. These results would be useful guide for the development of novel lead-less optoelectronic perovskite materials.

A Universal Strategy to Enhance Circularly Polarized Luminescence Brightness in Chiral Perovskites

AbstractChiral perovskites are considered as promising candidates for circularly polarized luminescence (CPL) light source, by attracting the broader scientific community for their applications in chiral optoelectronics and spintronics. However, it is still a great challenge to achieve both substantial photoluminescence asymmetry (gCPL) and high photoluminescence quantum yield (PLQY) simultaneously for high CPL brightness due to the limitations associated with magnetic transition dipole moments. Herein, this problem is overcome and achieve both large gCPL of 1.6×10−2 and PLQY of 56% in chiral perovskite through the magnetic element doping strategy. The substitution of Pb2+ ion with smaller magnetic Mn2+ ions shrinks the crystal lattice around [MnBr6]4− octahedra, amplifying the asymmetric distortion surrounding the Mn2+ ions. Moreover, the transition associated with Mn2+ ions can harvest the photoexcitation energy in chiral perovskites, and its spin‐flipping characteristics enable highly efficient CPL from the d–d transition on Mn2+ energy levels. Furthermore, this magnetic element doping strategy is proven to be a universal tactic for enhancing CPL brightness as confirmed in a series of 1D‐ or 2D‐chiral perovskites with various chiral ligands or halogens. The findings provide an in‐depth understanding of the structure‐property relationship in chiral perovskites toward chiral optoelectronic and spintronic applications.

Dual‐Doping Strategy of Metal Chlorides in Ambient Air with High Humidity for Achieving Highly Air‐Stable All‐Inorganic Perovskite Solar Cells

It is fundamentally challenging to achieve stable and efficient all‐inorganic perovskite solar cells (PSCs) in ambient air conditions for low‐cost commercial manufacturing, as the crystallinity, surface morphology, and optical activity of all‐inorganic perovskites exhibit high sensitivity to environmental factors such as moisture and illumination. Herein, a dual‐doping strategy is presented to prepare high‐quality dual‐doping CsPbI2Br films under ambient air with relative humidity of 70% (70% RH) by introducing CaCl2 and InCl3 additives into precursor solution. The results from the experiments and calculations reveal that the CaCl2 additive can isolate moisture by forming hydrates at the surface and grain boundary of perovskites. Meanwhile, the addition of InCl3 can significantly improve the optoelectronic properties via the heterovalent substitution of Pb2+ by a small amount of In3+. Moreover, the phase segregation can be significantly suppressed in the dual‐doping CsPbI2Br films owing to decreasing the electron–phonon coupling strength and increasing the activation energy of ion migration. The unencapsulated dual‐doping CsPbI2Br PSC with the power conversion efficiency (PCE) of 15.51% (70% RH) demonstrates high humidity storage and long‐term optical stability, remaining 90% of the original PCE after aging 2400 h under ambient air (50% RH) and 1500 h under continuous illumination, respectively.

Effects of Pb and carbonate substitutions on the superconducting properties of TlSr4Cu2OzCrO4

We have investigated the effects of Pb and carbonate substitutions on the phase formation and the superconducting properties of the intergrowth superconductor TlSr4Cu2OzCrO4. X-ray diffraction data showed that nearly single-phase samples with tetragonal structure were obtained in the compositions (Tl1-xPbx)Sr4Cu2OzCrO4 (0 ≤ x ≤ 0.5) and (Tl0.5Pb0.5)Sr4Cu2Oz(CrO4)1-y(CO3)y (0 ≤ y ≤ 1.0). Resistivity measurements indicated that the transition temperature decreased significantly as the Pb doping content x increased to x = 0.5. In contrast to the Pb doping effects, the carbonate substitution in the (Tl0.5Pb0.5)Sr4Cu2Oz(CrO4)1-y(CO3)y system resulted in an improvement of the superconducting transition temperature up to y = 0.9. The y = 1.0 sample showed a reduced transition temperature, compared to the x = 0.9 sample. The experimental results are discussed in conjunction with the change in hole carrier concentration due to the Pb and carbonate substitutions, based on the data from room temperature thermoelectric power measurements.

An insight into the structural, magnetic and dielectric properties of modified SrFe12-xPbxO19 (x = 0–0.3)

Effect of Pb2+ substitutions on the structural, magnetic and dielectric properties of SrFe12O19 in the form of SrFe12-xPbxO19 (x = 0, 0.1, 0.2 and 0.3) is carried out. All the samples crystalize in hexagonal magneto-plumbite structure with P63/mmc symmetry. An irregular but randomly distributed particles with average particle size increased from 0.791 μm to 1.131 μm due to substitutions. A characteristics Hopkinson peak is observed just below the transition temperature, may be stems from the superparamagnetic relaxations. The isothermal magnetization depicts an increase in coercivity (Hc) and decrease in saturation magnetization (Ms) due to Pb substitutions, which is further explained in the framework of site symmetry of the Fe and its multiple valence states. Mossbauer study reflects that, Fe3+/ Fe2+ present in the systems are associated with different electric environment. Furthermore, the shifting of dielectric transition by 50 °C upon substitutions is associated to dipole formation in presence of lone pair of Pb2+. A relaxor type of behavior is acquired by the system with a non-Debye type of relaxation is explained on the basis of complexity of the dipoles associated with each crystallographic sites.

Synthesis and characterization of (Pb1−x Sr x )MnBO4: a structural and spectroscopic study

Abstract The presence of ns 2 stereo-chemical active lone electron pairs (LEPs) causes asymmetric atomic environments around a given p-block cation, leading to change the crystal chemistry of a respective system. Here we report a series of mullite-type compounds to understand at what extend Sr2+ replaces the stereochemical active Pb2+ cation in (Pb1−x Sr x )MnBO4. Each member of the solid solution has been synthesized by conventional solid-state method. The polycrystalline samples are characterized using X-ray powder diffraction followed by Rietveld refinement. Substitution of Pb2+ with Sr2+ leads to contraction of the a lattice parameter with slight elongation in the b and c direction. For a difference of 1 pm of the ionic radius between Sr2+ and Pb2+, the cell volume contracts about 4 % between the end members as the spatial requirement of the LEP activity in the MBO4 2− channels significantly decreases. Within the solid solution, two distinct Pb/Sr–O2 bond distances significantly differ, which gradually decreases with increasing strontium content leading to a more symmetric coordination around strontium. The calculated BVS of Pb2+/Sr2+ exhibits a linear correlation with the Wang–Liebau eccentricity parameter, indicating to an increased bonding ability cation. The vibrational properties are characterized by both Raman and FTIR spectroscopy, complementing the XPRD results. Electronic band gaps of selected (Pb1−x Sr x )MnBO4 samples were obtained from diffuse reflectance spectroscopy data. Additionally, the Sr containing samples show higher thermal stability than the Pb containing counterparts.

Advancements and Prospects in Perovskite Solar Cells: From Hybrid to All-Inorganic Materials.

Hybrid perovskites, materials composed of metals and organic substances in their structure, have emerged as potential materials for the new generation of photovoltaic cells due to a unique combination of optical, excitonic and electrical properties. Inspired by sensitization techniques on TiO2 substrates (DSSC), CH3NH3PbBr3 and CH3NH3PbI3 perovskites were studied as a light-absorbing layer as well as an electron-hole pair generator. Photovoltaic cells based on per-ovskites have electron and hole transport layers (ETL and HTL, respectively), separated by an ac-tive layer composed of perovskite itself. Major advances subsequently came in the preparation methods of these devices and the development of different architectures, which resulted in an efficiency exceeding 23% in less than 10 years. Problems with stability are the main barrier to the large-scale production of hybrid perovskites. Partially or fully inorganic perovskites appear promising to circumvent the instability problem, among which the black perovskite phase CsPbI3 (α-CsPbI3) can be highlighted. In more advanced studies, a partial or total substitution of Pb by Ge, Sn, Sb, Bi, Cu or Ti is proposed to mitigate potential toxicity problems and maintain device efficiency.

Rashba and Dresselhaus effects in doped methylammonium lead halide perovskite MAPbI3.

Inorganic-organic lead halide perovskites, particularly methylammonium lead halide (MAPbI3) perovskite, have been regarded as promising materials for optoelectronics and spintronics. However, the practical applications of these perovskites are limited by lead toxicity and instability under air and pressure. This study investigates the substitution of Pb with Sn and Ge in cubic MAPbI3 perovskite. The properties of the resulting hybrid perovskites are compared using state-of-the-art first-principles-based methodologies, viz., density functional theory (DFT) with generalized gradient approximation (PBE) and hybrid functional (HSE06), in conjunction with spin-orbit coupling (SOC). Here, we mainly study the Rashba-Dresselhaus (RD) effect, which arises due to two major mechanisms: (i) the breaking of inversion symmetry (static and dynamic) and (ii) SOC, originating from the presence of heavy elements. We find significant spin-splitting effects in the conduction band minimum and valence band maximum for hybrid perovskites. To gain a deeper understanding of the observed spin-splitting, the spin textures are analyzed, and Rashba coefficients are calculated. We find that the Dresselhaus effect comes into play in substituted hybrid structures in addition to the usual Rashba effect observed in the pristine compound. Additionally, we observe that the strength of Rashba spin-splitting is substantially tuned by the application of uniaxial strain (±5%). Moreover, certain hybrid perovskites exhibit mechanical stability and ductility, making them potential candidates in perovskite-based optoelectronics and spintronics applications.

Atomic-scale insights in the interplay of chemical composition and chirality in two-dimensional chiral perovskites.

The incorporation of chiral molecules (A) in materials based on hybrid ABX3 perovskites has opened new paths to tune the optoelectronic properties of perovskites through the transfer of chirality to the inorganic BX framework. However, our atomistic understanding of the role of chemical BX composition in the magnitude of the chirality transfer is far from complete. In this study, we use density functional theory calculations and the experimental Ruddlesden-Popper chiral (R-/S-NEA)2PbBr4 structure (R-/S-NEA = R-/S-1-(1-naphthyl)ethylammonium) to investigate the effects induced by chemical substitution of Pb by Ge or Sn and Br by Cl or I on the transfer of chirality and physical-chemical properties. We have observed that different enantiomers result in opposing orientations of octahedral tiltings within the inorganic framework, thus transferring chirality to the inorganic structure. The tilts are greater in perovskites based on Pb and decrease in the sequence of Cl to Br to I, as a consequence of the decrease in the halide electronegativity that weakens the interactions between X and the -N+H3 group of the NEA chiral cation. The chirality transfer is also evident in the Rashba-Dresselhaus effects on the electronic band structure, in which we found magnitudes directly correlated to the trends of octahedra tilting. The band offsets of substitutions B and X are predominantly influenced by their natural atomic energy levels, while organic molecules play a pivotal role in modulating the ionic potential and electron affinity in systems containing light atoms. The band gap values range from 1.91 up to 3.77 eV, with chirality and anion electronegativity providing significant tuning effects on whether the band gaps are direct or indirect.

Thermoelectric properties of Bi1-xPbxCu1-xSeO oxyselenides.

In this work, Bi1-xPbxCu1-x SeO (x = 0, 0.02, 0.06, and 0.08) compounds were synthesized by a solid state reaction followed by spark plasma sintering. The effect of simultaneous Bi to Pb substitution and Cu vacancy introduction on thermoelectric properties was investigated systematically. The power factor was significantly enhanced, contributing to the increase in the zT value. As a result, the zTmax of 0.75 at 773 K was obtained for the Bi0.94Pb0.06Cu0.94SeO sample. To reveal the factors constraining the zTmax of Bi1-xPbxCuSeO-based oxyselenides, a further careful analysis of literature data was performed. We highlighted that for Pb-doped oxyselenides, the power factor is almost independent of the synthesis technique, while the lattice thermal conductivity is the main property determining zTmax and is highly affected by the synthesis method.

Migration pathway and solidification mechanism of heavy metal Pb during the conversion of municipal solid waste incineration fly ash into ettringite and simultaneously purification of chloride salts solution process

The solidification/stabilization of heavy metals and valuable component recovery from municipal solid waste incineration (MSWI) fly ash are of great significance for its safe disposal. In this study, MSWI fly ash was transformed into a new solid phase mainly composed of ettringite, achieving the solidification of excessive heavy metal Pb while obtaining a mixed solution of sodium chloride and potassium chloride with extremely low impurity content, which can be recovered by evaporation-crystallization respectively. The solidification mechanism of heavy metal Pb by ettringite was investigated through a combination of DFT calculations and experiments. The results indicate that a high conversion rate of calcium ions (99.68%), separation rate of chloride (95.99%), and conversion rate of heavy metal Pb (99.42%) can be achieved by controlling the ions ratio of the MSWI fly ash reaction system to n(Ca2+):n(Al3+):n(SO42−) = 6:2:3. DFT calculations show that the reaction pathway of the formation of a vacancy-Pb entering the vacancy at the Ca-2 site of ettringite is more likely to occur. The substitution of heavy metal Pb at the Ca-2 site leads to an increase in the unit cell volume, redistribution of charges, and a decrease in the thermal stability of the ettringite. The solidified body of ettringite presents a promising potential for application in cement-based materials due to its negligible risk of heavy metals leaching and low chloride content.

Enhancing second harmonic generation response in infrared nonlinear optical material through Pb substitution: A study of Li2PbSiS4compound

The demand for infrared nonlinear optical (IR-NLO) materials is increasing due to their applications in many civil and military fields. However, a critical challenge revolves around achieving a good balance between a large second harmonic generation (SHG) response and a high laser damage threshold (LDT). Based on earlier study on Li2SrSiS4 compound which showed good SHG and high LDT performances, and to afford one new NLO material, we propose, in this work to replace the Sr atom with a P-bloc (Pb) atom in the Li2SrSiS4 compound. According to DFT calculations, the newly designed Li2PbSiS4 compound crystallizes in the stable stannite structure. In addition, it is thermodynamically, dynamically and mechanically stable. The investigated material presents an indirect bandgap of 2.48 eV employing the HSE06 approach, including spin-orbit coupling (SOC) effects. Moreover, the calculated SHG response is 0.85 × AgGaS2, which is larger than the SHG response of Li2SrSiS4. Furthermore, the SHG response increases directly with temperature, allowing using the compound at high temperatures. The obtained results may make the Li2PbSiS4 compound a promising NLO material.

HPMC-Mediated ZnCl2 Doping Possible Substitution of Pb2+ for Environment-Friendly Halide Perovskite Solar Cell Fabrication

Research on halide perovskite solar cells is a rapidly evolving and active area of study within the field of photovoltaics. Replacement of lead from halide perovskite solar cells is a prerequisite due to its toxicity. In this research, an efficient and low surface defect of Zn2+ incorporated hybrid perovskite material was demonstrated, where Pb2+ is partially substituted with transitional metal Zinc. Herein, we report the incorporation of dopant material ZnCl2 with synthetic cellulose HPMC (Hydroxy propyl methyl cellulose) as a dopant to improve the surface morphology, crystallinity, and partial substitution of Pb2+ with Zn2+. Samples were prepared with different composition of ZnCl2 doping assisted with HPMC in MAPbI3 (methylammonium lead triiodide) for perovskite layer preparation. A device assembly of layer-by-layer architecture constituting FTO/TiO2(ETL)/MAPbI3/CuSCN(HTL) was fabricated for the experimental analysis. The as-prepared perovskite samples were characterized using different analytical tools to investigate optical absorption property, crystalline structure, functional group interaction, and surface morphology, respectively. Finally, the electrical performance of the perovskite solar cells was tested under AM 1.5 G solar illumination, and the data affirms that 10 wt% ZnCl2 doping assisted with HPMC media exhibits optimum performance with improved film quality.

Switching Lead for Tin in PbHfO3: Noncubic Structure of SnHfO3**

AbstractThe removal of lead from commercialized perovskite‐oxide‐based piezoceramics has been a recent major topic in materials research owing to legislation in many countries. In this regard, Sn(II)‐perovskite oxides have garnered keen interest due to their predicted large spontaneous electric polarizations and isoelectronic nature for substitution of Pb(II) cations. However, they have not been considered synthesizable owing to their high metastability. Herein, the perovskite lead hafnate, i.e., PbHfO3 in space group Pbam, is shown to react with SnClF at a low temperature of 300 °C, and resulting in the first complete Sn(II)‐for‐Pb(II) substitution, i.e. SnHfO3. During this topotactic transformation, a high purity and crystallinity is conserved with Pbam symmetry, as confirmed by X‐ray and electron diffraction, elemental analysis, and 119Sn Mössbauer spectroscopy. In situ diffraction shows SnHfO3 also possesses reversible phase transformations and is potentially polar between ≈130–200 °C. This so‐called ‘de‐leadification’ is thus shown to represent a highly useful strategy to fully remove lead from perovskite‐oxide‐based piezoceramics and opening the door to new explorations of polar and antipolar Sn(II)‐oxide materials.

Switching Lead for Tin in PbHfO3 : Noncubic Structure of SnHfO3.

The removal of lead from commercialized perovskite-oxide-based piezoceramics has been a recent major topic in materials research owing to legislation in many countries. In this regard, Sn(II)-perovskite oxides have garnered keen interest due to their predicted large spontaneous electric polarizations and isoelectronic nature for substitution of Pb(II) cations. However, they have not been considered synthesizable owing to their high metastability. Herein, the perovskite lead hafnate, i.e., PbHfO3 in space group Pbam, is shown to react with SnClF at a low temperature of 300 °C, and resulting in the first complete Sn(II)-for-Pb(II) substitution, i.e. SnHfO3 . During this topotactic transformation, a high purity and crystallinity is conserved with Pbam symmetry, as confirmed by X-ray and electron diffraction, elemental analysis, and 119 Sn Mössbauer spectroscopy. In situ diffraction shows SnHfO3 also possesses reversible phase transformations and is potentially polar between ≈130-200 °C. This so-called 'de-leadification' is thus shown to represent a highly useful strategy to fully remove lead from perovskite-oxide-based piezoceramics and opening the door to new explorations of polar and antipolar Sn(II)-oxide materials.

In situ trace element compositions of sulfides constraining the genesis of the worldclass Shuangjianzishan Ag-Pb-Zn deposit, NE China

The worldclass Shuangjianzishan Ag-Pb-Zn deposit, containing proven reserves of >21,665 t of silver @128.5 g/t, >3.3 Mt of lead @1.6 wt%, and >1.9 Mt of zinc @0.6 wt%, is the largest silver deposit in Asia. This giant Ag mineralization system has attracted extensive attention since its discovery. However, the incorporation mechanism of Ag in ore sulfides and the deposit genetic type are still greatly debated. We have conducted in situ LA-ICP-MS trace element analyses for sulfides in this deposit to address the above issues. Three paragenetic stages of mineralization were recognized at Shuangjianzishan, including pyrite + quartz + K-feldspar stage (I), galena + sphalerite + Ag-bearing sulfosalt + quartz + calcite + chlorite + sericite stage (II), and post-ore quartz stage (III). Most sulfides and silver minerals were deposited in stage II. In situ time-resolved depth profiles, principal component analysis (PCA), and correlation plots of trace element for sulfides indicate that trace elements are dominantly present in sulfides as solid solutions and nano-inclusions, and less as micro-inclusions. For silver, the most critical element in the studied deposit, its substitution mechanisms vary largely among sphalerite, pyrite, and galena. In sphalerite, Ag enters the crystal lattice associated with coupled substitution of Zn by Fe, Sn, Sb, and Ga. In pyrite, Ag enters the lattice through the coupled substitution of Fe by Cu, Zn, and Sn. In galena, Ag enters lattice by the coupled substitution of Pb by Sb and Zn. Based on the GGIMFis geothermometer calculations, the temperatures for ore stage II range from 290° to 333 ℃ (mean of 319 ℃), which are almost identical to the results of the sulfur isotope geothermometry and fluid inclusion thermometry from the previous studies. Furthermore, the trace element distributions in the Shuangjianzishan sulfides, e.g., the enrichment of Fe, Mn, Sn, Cu, Ag, Sb and Pb and the depletion of Ga, Ge, Co and In in sphalerite, as well as the geological and geochemical features, infer that the studied deposit is similar to the typical epithermal type deposit. We therefore propose that the worldclass Shuangjianzishan Ag-Pb-Zn deposit is an epithermal deposit, and this contribution indicates that in situ LA-ICP-MS trace element analysis of sulfides could help shed light on identifying the genetic type for the hydrothermal ore deposits.

Comparative Study of Magnetic Properties of (Mn1−xAxIV)Bi2Te4 AIV = Ge, Pb, Sn

We investigated the magnetic properties of the antiferromagnetic (AFM) topological insulator MnBi2Te4 with a partial substitution of Mn atoms by non-magnetic elements (AIV = Ge, Pb, Sn). Samples with various element concentrations (10–80%) were studied using SQUID magnetometry. The results demonstrate that, for all substitutes the type of magnetic ordering remains AFM, while the Néel temperature (TN) and spin-flop transition field (HSF) decrease with an increasing AIV = Ge, Pb, Sn concentration. The rate of decrease varies among the elements, being highest for Pb, followed by Sn and Ge. This behavior is attributed to the combined effects of the magnetic dilution and lattice parameter increase on magnetic properties, most prominent in (Mn1−xPbx)Bi2Te4. Besides this, the linear approximation of the experimental data of TN and HSF suggests higher magnetic parameters for pure MnBi2Te4 than observed experimentally, indicating the possibility of their non-monotonic variation at low concentrations and the potential for enhancing magnetic properties through doping MnBi2Te4 with small amounts of nonmagnetic impurities. Notably, the (Mn1−xPbx)Bi2Te4 sample with 10% Pb substitution indeed exhibits increased magnetic parameters, which is also validated by local-probe analyses using ARPES. Our findings shed light on tailoring the magnetic behavior of MnBi2Te4-based materials, offering insights into the potential applications in device technologies.

AEAg7(PS4)3 (AE = Ba, Sr): The homovalent substitution of lead by alkaline earth metals achieves the separation of the two phases and enlarges the band gap

Two alkaline earth metal-containing thiophosphate compounds, BaAg7(PS4)3 and SrAg7(PS4)3, were synthesized via the homovalent substitution of Pb2+ in PbAg7(PS4)3 by Ba2+ and Sr2+, respectively. The space group of BaAg7(PS4)3 (P21/c) and SrAg7(PS4)3 (P63/m) is the same as the low- and high-temperature phases of PbAg7(PS4)3, respectively. The two compounds exhibit structural similarity and possess three-dimensional honeycomb-shaped architectures. These honeycomb structures are arranged in a layered fashion via hexagonal rings, which arise from the sharing of edges or vertices between [AgS4] and [PS4] tetrahedral, accommodating discrete entities of Ba2+ and Sr2+ cations. BaAg7(PS4)3 melts congruently with a melting point of 760 °C and a solidification point of 675 °C, while the melting behaviour of SrAg7(PS4)3 was incongruently and thermally stable up to 689 °C under vacuum of 1 × 10−3 Pa. Moreover, the band gaps of BaAg7(PS4)3 (2.69 eV) and SrAg7(PS4)3 (2.85 eV) have a significant enlargement compared to PbAg7(PS4)3 (2.09 eV). The combination of d10 cation Ag+ with second-order Jahn-Teller distortion and alkaline earth metals cation enriches the system of new metal thiophosphates and provides ideas for exploring other functional materials.

Influence of Pb substitution in the charge reservoirs of Bi-2212 superconductors on pinning potential and superconducting properties

Influence of Pb substitution in the charge reservoirs of Bi-2212 superconductors on pinning potential and superconducting properties