Sn Compounds Research Articles

A DFT study to explore structural, electronic, optical and mechanical properties of lead-free Na2MoXO6 (X = Si, Ge, Sn) double perovskites for photovoltaic and optoelectronic applications

In this study we have performed DFT based calculations on lead-free Na2MoXO6 (X = Si, Ge, and Sn) double perovskites (DPs) for photovoltaic and optoelectronic applications. Trans-Blaha modified Becke-Johnson potential (TB-mBJ) approximation is used to calculate electronic properties of the given materials. All the given perovskites are found in cubic symmetry exhibiting semiconducting nature with energy band gap ∼1.77 eV, 1.65 eV and 1.33 eV, respectively. The calculated values of tolerance factor τ and negative formation energy demonstrate the structural and thermodynamic stabilities of all the investigated compounds. The elastic study demonstrates the ductile and anisotropic nature of Na2MoXO6 (X = Si, Ge, and Sn) compounds. In addition Na2MoXO6 (X = Ge, and Sn) compounds exhibit large absorption coefficient in visible light among the investigated perovskites. Overall the study demonstrates the suitability of investigated compounds for solar cell and other optoelectronic devices because of their narrow band gap and absorption performance.

Structural, mechanical, electronic, magnetic, optical, and thermoelectric properties of a new equiatomic quaternary heusler compound FeZrCrZ (Z = Si, Ge, Sn): A first-principles investigation

In this investigation, we undertake an ab initio exploration of the structural, mechanical, electronic, magnetic, optical, and thermoelectric characteristics of equiatomic quaternary Heusler compounds (EQH), specifically FeZrCrZ (Z = Si, Ge, Sn). Our investigation involves the utilization of the full-potential linearized augmented plane wave method (FP-LAPW) in density functional theory (DFT) framework, employing the generalized gradient approximation (GGA). The findings reveal that the Y-type-I arrangement, demonstrating ferromagnetic alignment, emerges as the most thermodynamically favored configuration among all FeZrCrZ (Z = Si, Ge, and Sn) compounds. Computed values for formation energy substantiate the feasibility of experimental synthesis.Furthermore, we meticulously determine elastic constants, confirming the structural robustness of the quaternary compounds. Dynamic stability analysis reinforces their stability. Electronic property assessments unveil the semi-metallic nature of FeZrCrZ (Z = Si, Ge, and Sn) alloys, showcasing complete spin polarization at the Fermi energy (100 %), a minimal energy gap, and magnetic moments of 2 μB when Z = Si, Ge, and 4 μB when Z = Sn. Optical property calculations encompass complex refractive index, dielectric function, reflectivity, absorption coefficient, and optical conductivity, indicating potential suitability of these compounds for optoelectronic applications. Employing Boltzmann transport theory, we investigate the thermoelectric performance of the compounds concerning temperature, and chemical potential. Evaluation of the thermoelectric response underscores their viability as thermoelectric materials, linked to a substantial figure of merit, increased Seebeck coefficient, and diminished thermal conductivity. This study provides crucial theoretical insights for experimental researchers, offering valuable information for the synthesis and application of these compounds in spintronics, thermoelasticity, and optoelectronics.

Germanium and Tin Precursors for Chalcogenide Materials Containing N-Alkoxy Thioamide Ligands.

This study describes the synthesis of germanium and tin complexes Ge(mdpaS)2 (1), Ge(edpaS)2 (2), Ge(bdpaS)2 (3), Ge(empaS)2 (4), Sn(mdpaS)2 (5), Sn(edpaS)2 (6), Sn(bdpaS)2 (7), and Sn(empaS)2 (8) (mdpaSH = (Z)-N-methoxy-2,2-dimethylpropanimidothioic acid; edpaSH = (Z)-N-ethoxy-2,2-dimethylpropanimidothioic acid; bdpaSH = (Z)-N-(tert-butoxy)-2,2-dimethylpropanimidothioic acid; empaSH = (Z)-N-ethoxy-2-methylpropanimidothioic acid), using newly designed N-alkoxy thioamide ligands as precursors for metal chalcogenide materials. All complexes were characterized using various analytical techniques, and the single-crystal structures of complexes 5 and 7 revealed a distorted seesaw geometry in the monomeric SnL2 form. Thermogravimetric (TG) curves showed differences between Ge compounds, which exhibited single-step weight losses, and Sn compounds, which exhibited multistep weight losses. As a result, we suggest that the synthesized complexes 1-8 are potential precursors for group IV metal chalcogenide materials.

Metal Ion-Induced Acid Hydrolysis Strategy for the One-Step Synthesis of Tough and Highly Transparent Hydrolyzed Polyacrylamide Hydrogels.

Polyacrylamide (PAM) hydrogel is hard to enhance through coordination bonds because amide groups rarely coordinate with metal ions strongly in an aqueous solution. It is known that the aqueous solution of ZrOCl2.8H2O can be strongly acidic depending on its concentration. Consequently, through a facile one-step metal ion-induced acid hydrolysis strategy (MIAHS), tough and highly transparent hydrolyzed PAM physical hydrogels are prepared by using ZrOCl2.8H2O in this work. The formation of the partially hydrolyzed PAM physical hydrogels elucidates that the side reaction of imidization during common acid hydrolysis of PAM can be perfectly overcome because the structure of the Zr(IV) ion and its interaction with amide groups promote selective acidic hydrolysis from amide to carboxyl groups. Compared to most coordination cross-linked hydrogels, which need at least two-step fabrication, the hydrolyzed PAM hydrogel via MIAHS can be obtained by one-step synthesis due to the weak interaction between amide groups and Zr(IV). The obtained PAM hydrogel cross-linked by hydrogen bonds and coordination bond between Zr(IV) and carboxyl is a multibond network (MBN) and can achieve hierarchical energy dissipation, which exhibits excellent mechanical properties (tensile strength of 3.15 MPa, elongation at break of 890%, and toughness of 17.0 MJ m-3), high transparence (transmittance of 95%), and outstanding conductivity (5.6 S m-1) at water content of 80 wt %. The high gauge factor (from 2.24 to 12.8 as the strain increases from 0 to 400%) endows the hydrolyzed PAM hydrogels with promising application as strain sensors. Furthermore, in addition to ZrOCl2.8H2O, the fact that various hydrolyzable compounds of Ti(IV), Zr(IV) Hf(IV), and Sn(IV) can also fabricate tough hydrolyzed PAM hydrogels verifies the universality of MIAHS. Therefore, the simple, efficient, and universal MIAHS will shed new light on preparing functional PAM-based hydrogels.

Effect of E-waste copper alloy additions on the microstructure and organization of Cu90PSn brazing joints.

The effects of different contents of e-waste alloy on the microstructure and joint properties of Cu90PSn brazing filler metal was investigated during copper and copper brazing. Microstructure of base metal and brazing filler metal was studied with scanning electronic microscopy (SEM). The properties of brazing joint obtained by adding different electronic waste filler metal for smelting copper alloy were compared together. The results indicated that the fluidity of Cu90PSn brazing filler metal was weakened and the spreading property of Cu90PSn brazing filler metal was damaged after the addition of e-waste copper alloy. The structure of Cu90PSn brazing filler metal is mainly composed of (Cu), Cu3P and (Cu,Sn) compounds. When a small amount of electronic waste copper alloy is added, a trace amount of Fe in the brazing filler metal is distributed in the matrix structure of the filler metal in the form of solid solution. With the increase of copper alloys contents by smelting e-waste, Fe content in Cu90PSn brazing filler metal increases; the granular Fe3P phosphide changes into lamellar form. The Cu3P compound phase changes from continuous large orderly arrangement to discontinuous small block structure. Therefore, adding a trace amount of electronic waste copper alloy to the solder induction brazing copper/copper can obtain a uniform composition of the brazing structure. And the welding performance is not affected. However, As the content of e-waste smelted copper alloy continues to increase, the tensile strength shows a downward trend, which is attributed to the presence of brittle compound Fe3P in the joint.

Theoretical studies on phase stability, electronic, optical, mechanical and thermal properties of chalcopyrite semiconductors HgXN2 (X=Si, Ge and sn): A comprehensive DFT analysis

In this study, the ground state physical properties of Hg-based chalcopyrite semiconductors, HgXN2 (X = Si, Ge and Sn), are investigated using the density functional theory (DFT), which is based on full potential linearized augmented plane wave (FP-LAPW) method. The structural, electronic, optical, mechanical and thermal properties of the body-centered tetragonal (BTC) phase, HgXN2 (X = Si, Ge and Sn), have been calculated using the modified Becke-Johnson exchange-correlation potential (TB-mBJ). The obtained lattice parameters and volume are in good agreement with the values reported earlier, indicating that the results are reliable and reproducible. The phase stability of the titled compounds is elaborately studied and it is confirmed that all are thermodynamically, dynamically and mechanically stable. The electronic band structure demonstrated a direct band gap of 1.70 eV, 0.99 eV, and 0.94 eV for the HgXN2 (X = Si, Ge and Sn) compounds, respectively. Both HgGeN2 and HgSnN2 compounds have a notably lighter carrier effective mass, resulting in higher carrier mobility and conductivity than HgSiN2. The order of the mechanical hardness is as follows: HgSiN2> HgGeN2> HgSnN2. The studied materials are also anisotropic in mechanically and optically. All the title compounds exhibit ductile behavior. The charge density contour plots indicates the dominant covalent nature of the bonds in HgXN2 (X = Si, Ge and Sn). All these compounds have a high absorption coefficient and low optical reflectivity in the visible light range. Due to the favorable band gap and high absorption coefficient, these compounds could be suitable for optoelectronic or photovoltaic device applications. Moreover, the thermal expansion coefficient, thermal conductivity, melting point and fracture toughness behavior have been calculated, which also showed promise for thermal barrier coating (TBC) applications.

Response of Mg2X (X = Si, Ge and Sn) compounds to extreme uniaxial compression: first-principles calculations

Abstract In this study, we perform first-principles calculations using density functional theory to examine the structural, electronic, thermodynamic, and thermoelectric properties of the Mg2X (X = Si, Ge and Sn) compounds under uniaxial compression within the generalized gradient and modified Becke–Johnson approximations. It is found that the band gap of Mg2Si, Mg2Ge and Mg2Sn decreases with applied uniaxial pressure and changes its direction from Γ-X to Γ-K. The results of phonon frequencies indicate that the studied compounds are dynamically stable at zero and higher uniaxial strains. Furthermore, the uniaxial compression and temperature dependence of the Gibbs free energy, heat capacity and thermal expansion coefficient are investigated in the frame of the quasi-harmonic approximation. The semiclassical-Boltzmann method is used to study the Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit ZT as a function of both temperature and uniaxial pressure. It is shown that the Seebeck coefficient decreases with increasing pressure whereas thermal conductivity increases, which leads to the lowering in the value of ZT and thus to a worse thermoelectric performance of the studied materials.

Prediction of ternary alkaline-earth metal Sn(II) and Pb(II) chlorides with potential applications as p-type transparent conductors.

Non-metallic Sn(II) and Pb(II) compounds, particularly those with p-type properties, are essential functional materials due to their notable electronic arrangement and chemical characteristics. The presence of additional Sn(II) and Pb(II) chlorides is suggested by the existence of known Sn(II) and Pb(II) compounds. By utilizing first-principles calculations and swarm intelligence structure search techniques, we have predicted the existence of up to seven new ternary alkaline-earth metal chlorides: ABCl4 (where A = Sr and B = Sn or Pb) and AB2Cl6 (where A = Mg, Ca, or Ba and B = Sn, or A = Ca or Sr and B = Pb). These seven chlorides are in the divalent state. The interaction between Sn-5s (or Pb-6s) and Cl-3p in these compounds creates an anti-bonding effect in the upper valence bands, which enhances defect tolerance and promotes high p-type conductivity. These stable chlorides exhibit notable electronic properties, including wide band gaps ranging from 3.91 to 4.94 eV, broad hole effective masses ranging from 0.93 to 5.62 m0, and high valence band alignments ranging from 6.83 to 8.38 eV under vacuum. In particular, Ca/BaSn2Cl6 and CaPb2Cl6 have the potential to be used as p-type transparent conductors due to their favorable properties, including a lower hole effective mass (0.93 m0 for CaPb2Cl6) and higher ionization potentials (6.83/7.05 eV for Ba/CaSn2Cl6). Furthermore, the predicted CaPb2Cl6 crystal exhibits attenuated negative linear compressibility and negative zero-linear-compressibility along the c-axis in different pressure ranges due to its wine-rack structure. This report highlights potential applications for alkaline-earth metal Sn(II) and Pb(II) chlorides, including their use as transparent conductors, particularly p-type conductors.

Effect of Nano-Cu6Sn5 upon development mechanism of Cu–Ni–Sn compounds and mechanical characteristics for mixed solder joints

This investigation aimed to examine the development mechanism of Cu–Ni–Sn compounds and analyze the mechanical properties of mixed solder (MS) joints. Results show that an intermetallic compound (IMC) layer was formed in an SAC305 solder joint prepared herein comprising (Ni, Cu)3Sn4 and (Cu, Ni)6Sn5 phases following the reflow process. The morphology of the (Cu, Ni)6Sn5 grains was identified to be dodecahedral. Meanwhile, the IMC layer of the prepared MS joints contained only the (Cu, Ni)6Sn5 phase, which exhibited a hexagonal prism morphology. The lattice characteristics of Cu6Sn5 changed after Ni dissolution, forming (Cu, Ni)6Sn5 crystals with an X-shaped morphology in the MS joints that exhibited a high Cu content during the aging process. After reflow, the MS joints exhibited slightly higher shear strength than the SAC305 solder joint. After aging at 165 °C for 1000 h, the shear strength of the SAC305 solder joint reduced by 21.72% compared to its value after reflow owing to the annexation of Sn grains. However, the number of Sn grains in the MS joints did not considerably decrease after aging. Further, the grain boundaries of β-Sn and (Cu, Ni)6Sn5 particles contributed to the strengthening of the MS joints. The shear strength of the MS joints decreased by 11.06%–18.35% after aging.

Theoretical investigation the effect of A-site elements on mechanical and thermal properties in Ti2AC (A = Al, Ga, In, Si, Ge, Sn) compounds

To better understanding the effect of group-A atoms on the properties in Ti2AC (A = Al, Ga, In, Si, Ge, Sn) compounds, the phase stability, elastic properties, electronic structures and thermal properties of the compounds were calculated using density functional theory (DFT). The results revealed that the A-site elements affect largely the lattice constant c than the lattice constant a. The compounds are thermodynamically and mechanically stable. Ti2SiC has higher bulk modulus with 163.7 GPa, which makes it has higher compression resistance among the Ti2AC family. Ti2InC has the lowest hardness because of it has the smallest shear modulus (103.8 GPa) and C44 (95.1 GPa) among the Ti2AC family. The chemical bond of all compounds is a combination of metallic and covalent bonds characteristic. In addition, Ti2AlC has the largest Debye temperature of 751.5 K, while Ti2InC and Ti2SnC possess the smallest value of 546.9 K, which indicate that Ti2InC and Ti2SnC compounds are potential materials for thermal barrier coating (TBC) applications. This work will provide a valuable theoretical basis for further study of Ti2AC ternary carbides with excellent mechanical and thermal properties.

Impact of M‐Site Cation Variation on Structural, Electronic, and Optical Properties of Pd3M2Se2 (M = Pb, Sn) Dichalcogenides: A Computational Study

AbstractThe optimized structure of Pd3M2Se2 (M = Pb and Sn) compounds is used to explore the M‐Site cation variation. Density functional theory (DFT) using generalized gradient approximation (GGA) with Hubbard potential (GGA+U) and Wu and Cohen (GGA+WC) functionals are used to examine the physical characteristics. The chemical stability is indicated by negative values for the formation energy and obtained as −26.75 eV and −28.25 eV for Pd3Pb2Se2 and Pd3Sn2Se2 compounds respectively. The feeble interaction of Se‐4p and Pb‐6p orbital electrons in the conduction band results in a considerable contribution. As a result, the energy bands of the Pd3Pb2Se2 structure are altered in such a way that it has a high electrical conductivity. The Pd3Pb2Se2 and Pd3Sn2Se2 structures are metallic, with both ionic and covalent interactions, according to electronic population studies. While the extinction coefficient for the Pd3Pb2Se2 compound is 4.20 at 0.65 eV, the Pd3Sn2Se2 structure has a highest peak of 7.20 at this energy, indicating their photoelectric applicability. The Pd3Pb2Se2 and Pd3Sn2Se2 structures seemed to be transparent to photons energy at 16.4 eV and 18.20 eV respectively. These shandite compounds showed superior absorption for Ultraviolet (UV) photon energy as well as efficient infrared and visible light absorption with conductivity.

DFT-based computational investigations of the structural, electronic, elastic, and magnetic properties of ternary Half-Heusler TiVX (X = Ge, Si, Pb, Sn) compounds

Herein, the full-potential linearized augmented plane wave (FP-LAPW) scheme within the density functional theory (DFT) interface within the simulation code of WIEN2K is employed to investigate the TiVX (X = Ge, Si, Pb, Sn) Half-Heuslers compounds. The incorporated Hubbard U-terms for coulomb's potential in generalized gradient approximation (GGA+U) potential is carried out for the prediction of interested properties. Through our investigations, we found that all of these compounds exhibit semiconductor characteristics in the spin-up configuration. Specifically, we have observed a narrow band gap above the Fermi level, indicating their N-type semiconductor behavior. In contrast to the spin-up configuration, it has been observed that these compounds also possess a narrow band gap below the Fermi level in the spin-down configuration. This finding suggests that these materials exhibit P-type behavior. Due to the varied semiconducting nature at the Fermi levels, these compounds are 100% spin-polarized. Regarding their structural properties, these compounds have been observed to exhibit a higher level of stability, with equilibrium lattice constants falling within the range of 6 Å to 6.5 Å. Magnetic properties reveal that for all these compounds the total magnetic moment is greater than 4 μB, i.e. Mtot > 4 μB, which depicts the strong ferromagnetic behavior. It is observed from the elastic properties that TiVX (X = Ge, Si, Pb, Sn) compounds are ductile, hard, and possess an anisotropic nature. Based on the aforementioned findings for TiVX (X = Ge, Si, Pb, Sn), we have identified promising applications for these compounds in a wide range of semiconducting devices, spintronics, and various other advanced electronic devices.

Commissioning of a two-target DC cylindrical magnetron sputter coater for depositing Nb₃Sn film on Nb superconducting radiofrequency cavities

A DC cylindrical magnetron sputter coater was commissioned and used to coat Nb 2.6 GHz superconducting radiofrequency (SRF) cavity with Nb3Sn. The sputter coater has two identical cylindrical magnetrons that can move, with a controlled speed, along the axis of the SRF cavity to coat the inside surface of the cavity. The design of the sputter coater is discussed, along with its performance. Initially, a sample holder that allows coating on flat substrates at positions similar to the equator and beam tubes of a 2.6 GHz SRF cavity was used to test conditions for fabricating Nb3Sn layers. Multilayers of Nb and Sn were sequentially sputtered on flat Nb and sapphire substrates mounted on the equivalent positions of the cavity's beam tubes and the equator using the two identical cylindrical magnetrons. Then, the Nb/Sn multilayers were annealed at 950 °C for 3 h. The ∼1.2 μm thick Nb3Sn film did not show any other Nb–Sn compounds and had a superconducting transition temperature of 17.61–17.76 K. The 2.6 GHz SRF cavity was coated using similar conditions as flat samples. Cryogenic RF testing of the Nb3Sn-coated cavity demonstrated a quality factor of 3.2 × 108 at an accelerating gradient of 5 MV/m at 4.4 K.

In-situ fusion process and Cu–Sn compounds evolution mechanism of nano-intermetallic compound mixed solder joints

This study investigated the fusion and phase-transformation processes of nano-intermetallic compound (nano-IMC) mixed solder pastes. In particular, the interfacial reaction with the Cu substrate, the kinetics and mechanism of Cu6Sn5 growth inside the solder joint, and the shear strength of the solder joint were investigated. In-situ SEM and XRD results showed that the SAC305 and Sn–10Cu powders fused and the liquid solder ball completely melted at 227 °C. A higher initial Cu concentration in the mixed solder joints resulted in a lower Cu concentration gradient that inhibited the diffusion of Cu atoms. The growth activation energy of the IMC layer of a SAC305 + 20 wt% Sn–10Cu solder joint was 104.81 kJ/mol, which was higher than that of the SAC305 IMC layer (75.75 kJ/mol). During aging, Cu6Sn5 rods within the mixed solder joint formed gullies on the outer facets, and the Cu6Sn5 rods continued to grow along the [0001] crystal direction. The number of Sn grains and the proportion of high-angle grain boundaries in the mixed solder joints were higher after reflow. After aging at 150 °C for 1000 h, the shear strength of the SAC305 + 20 wt% Sn–10Cu solder joints was 34.25 MPa, slightly higher than that of SAC305 (33.12 MPa).

Ab-initio investigations for structural, optoelectronic and thermoelectric properties of Li2BeXSe4 (X = Ge, Si, Sn) compounds

Motivated by photovoltaic activities, we study certain aspects of the stannite structure (ST) of the Li2BeXSe4 (X = Ge, Si, Sn) compounds using the full potential augmented plane wave approach implemented in the Wien2k code. Concretely, we use the generalized gradient approximation (GGA) and the modified Becke–Johnson exchange potential (mBJ) to evaluate in a precise way, the band gaps, the total and the partial densities, as well as the optical and the thermoelectric properties. Among others, we show that the Li2BeXSe4 (X = Ge, Si, Sn) semiconductors exhibit a direct band gap in the Γ point of the Brillouin Zone (BZ). Furthermore, the optical properties of the three compounds show a strong optical conductivity and a good optical absorption. As a result, we reveal that the proposed materials are suitable for the application in photovoltaic solar cells. Using the BoltzTrap package, we also examine and discuss the thermoelectric properties such as the Seebeck coefficient (S), the electrical conductivity, and the thermal conductivity as a function of the temperature. We find that the Li2BeXSe4 (X = Ge, Si, Sn) compounds exhibit good thermoelectric transport properties, making them a good candidates for clean energy applications.

Reducing Exact Two-Component Theory for NMR Couplings to a One-Component Approach: Efficiency and Accuracy.

The self-consistent and complex spin-orbit exact two-component (X2C) formalism for NMR spin-spin coupling constants [ J. Chem. Theory Comput. 17, 2021, 3874-3994] is reduced to a scalar one-component ansatz. This way, the first-order response term can be partitioned into the Fermi-contact (FC) and spin-dipole (SD) interactions as well as the paramagnetic spin-orbit (PSO) contribution. The FC+SD terms are real and symmetric, while the PSO term is purely imaginary and antisymmetric. The relativistic one-component approach is combined with a modern density functional treatment up to local hybrid functionals including the response of the current density. Computational demands are reduced by factors of 8-24 as shown for a large tin compound consisting of 137 atoms. Limitations of the current ansatz are critically assessed for Sn, Pb, Pd, and Pt compounds, i.e. the one-component treatment is not sufficient for tin compounds featuring a few heavy halogen atoms.

Investigation of the dynamical stability, electronic and thermoelectric properties of RhMnTiZ (Z=Si, Ge, Sn) Heusler compounds

We theoretically investigated the physical properties of RhMnTiZ (Z = Si, Ge, Sn) compounds. The negative formation energies and the phonon dispersions indicate the structural and dynamical stability of RhMnTiZ (Z = Si, Ge, Sn) compounds. The result of electronic band structures shows that the RhMnTiZ (Z = Si, Ge, Sn) compounds have indirect band gaps with 0.60, 0.42 and 0.22 eV using mBJ-GGA, respectively. The various transport properties of the RhMnTiZ (Z = Si, Ge, Sn) compounds are calculated using Boltztrap code. The large Seebeck coefficient and power factor of RhMnTiZ (Z = Si, Ge, Sn) at positive chemical potential suggest that they are new promising candidates for n-type thermoelectric materials.

Theoretical insights into the structural, optoelectronic, thermoelectric, and thermodynamic behavior of novel quaternary LiZrCoX (X = Ge, Sn) compounds based on first-principles study.

The structural, magnetic, electronic, elastic, vibrational, optical, thermodynamic as well as thermoelectric properties of newly predicted quaternary LiZrCoX (X = Ge, Sn) Heusler compounds are evaluated intricately with the aid of ab initio techniques developed under the framework of density functional theory. The computed structural properties are found to be in tandem with the existing analogous theoretical and experimental facts. Structural optimization has been carried out in three different structural arrangements, i.e., Type-1, Type-2, and Type-3. Further analysis of the optimization curves reveals that the Type-3 phase, which has the least amount of energy, is the most stable structure for the compounds under consideration. The tabulated cohesive energy and formation energy of these compounds depict their chemical as well as thermodynamic stability. The absence of negative phonon frequencies in the phonon band spectrum of the studied compounds depicts their dynamic stability. Similarly, the tabulated second-order elastic constants (Cij) and the linked elastic moduli show their stability in the cubic phase. The calculated value of Pugh's ratio and Cauchy pressure reveal that LiZrCoGe is brittle whereas LiZrCoSn is ductile. Additionally, the optical characteristics of the compounds are studied in terms of the dielectric function, refractive index, extinction coefficient, absorption coefficient, reflectivity, energy loss function, and optical conductivity. The obtained high value of power factor and figure of merit of the studied lithium-based quaternary compounds predict good thermoelectric behavior in these compounds. Thus, LiZrCoX (X = Ge, Sn) compounds can therefore be used to create innovative and intriguing thermoelectric materials as well as optoelectronic and energy-harvesting equipment.

Molecular Structures of the Pyridine-2-olates PhE(pyO)3 (E = Si, Ge, Sn)—[4+3]-Coordination at Si, Ge vs. Heptacoordination at Sn

The phenyltetrel pyridine-2-olates PhE(pyO)3 (E = Si, Ge, Sn; pyO = pyridine-2-olate) were synthesized from the respective chlorides PhECl3 and 2-hydroxypyridine (2-pyridone) with the aid of a sacrificial base (triethylamine). Their solid-state structures were determined by single-crystal X-ray diffraction. PhSi(pyO)3 exhibits a three-fold capped tetrahedral Si coordination sphere ([4+3]-coordination, Si···N separations ca. 3.0 Å), in accordance with structures of previously reported silicon pyridine-2-olates. PhGe(pyO)3 adopts a related [4+3]-coordination mode, which differs in terms of the tetrahedral faces capped by the pyridine N atoms. Additionally, shorter Ge···N separations (2.8–2.9 Å) indicate a trend toward tetrel hypercoordination. PhSn(pyO)3 features heptacoordinate tin within a pentagonal bipyramidal Sn coordination sphere (Sn···N separations 2.2–2.4 Å). For the Si and Sn compounds, 29Si and 119Sn NMR spectroscopy indicates retention of their tetrel coordination number in chloroform solution.

Half-metallic and thermodynamic properties of new d 0 CsCaZ (Z= Ge, Sn and Pb) half Heusler alloys: A spin-based devices vision for the future

Density functional theory (DFT) was applied to investigate the structural, electronic, elastic, magnetic, thermodynamic and half-metallic properties of the newly d0 Heusler alloys (HAs) CsCaZ (Z= Ge, Sn and Pb). Spin-polarised calculations show that the compounds studied are half-metallic with a magnetic moment of 1.00 μB at the equilibrium lattice parameter, which obeys the well-known Slater–Pauling rule Mtot = 8 – Zt. The half-metallic behavior of the compounds CsCaGe, CsCaSn and CsCaPb is predicted with respect to the equilibrium lattice constants for CsCaGe, CsCaSn and CsCaPb with a narrow band gap in the majority spin channel. Furthermore, the elastic constants (Cij) showed that these materials are ductile and anisotropic. In addition, the negative values of the calculated formation energy and cohesion energy indicate that CsCaZ (Z= Ge, Sn and Pb) are likely to be experimentally synthesized. Non-equilibrium Gibbs function is employed to calculate the thermodynamic properties through the quasi-harmonic Debye model in which the bulk modulus, heat capacity, Debye temperature, thermal expansion coefficient, and entropy are investigated at 0-20 Gpa pressure and 0-1200 K temperature ranges. The significant half-metallic behavior makes the CsCaZ (Z= Ge, Sn and Pb) compounds strong candidates for spintronic applications.