Crystalline Boragermenes

Boragermene 3 featuring a double bond between the Ge and dicoordinate B atoms has been synthesized for the first time by reacting the cyclic (alkyl)(boryl)germylene–PMe₃ adduct 1 with Cl₂BN(SiMe₃)₂ followed by reductive dehalogenation with KC₈. Addition of a Lewis base (^MeNHC) to 3 leads to the formation of the corresponding adduct 4 , which shows double bond character between the Ge and tricoordinate B atoms. Compound 3 undergoes hydrogenation with H₂ concomitant with a complete scission of the Ge=B bond.     

Reaction of germabenzenylpotassium with TBDMSCl: Unusual trimerization of germabenzene skeletons

Abstract

The reaction of 2-t-Bu-germabenzenylpotassium with Me₂(t-Bu)SiCl (TBDMSCl) resulted in the coupling among two TBDMS-substituted germabenzenes and the germabenzenylpotassium. The structure of the product was determined by X-ray crystallographic analysis. Its formation mechanism was proposed with the help of theoretical calculations.     

TDPAC and first-principles study of electronic and structural properties of a Pd-vacancy complex in undoped germanium

Pd is one of the metals suitable for inducing low-temperature crystallization in Ge. However, it is not clear how residual Pd atoms are integrated into the Ge lattice. Therefore, time-differential γ–γ perturbed angular correlations (TDPAC) technique using the ¹⁰⁰Pd(→¹⁰⁰Rh) nuclear probe produced by recoil implantation has been applied to study the hyperfine interactions of this probe in single-crystalline undoped Ge. A Pd-vacancy complex aligned along the <111> crystallographic direction with a unique interaction frequency of 8.4(5) Mrad/s has been identified. This complex was measured to have a maximum relative fraction of about 76(4)% following annealing at 350 ^°C. Further annealing at higher temperatures reduced this fraction, possibly via dissociation of the complex. Calculations suggest dissociation energy of 1.94(5) eV for the complex. DFT calculations performed in this work are in reasonable good agreement with the experimental values for the electric-field gradient of the defect complex in Ge and Si for comparison. The calculations predict a split-vacancy configuration with the Pd on a bond-centred interstitial site having a nearest-neighbour semi-vacancy on both sides (V-Pd_BI-V) in Ge and Si.     

Leaching of zinc and germanium from zinc oxide dust in sulfuric acid-ozone media

A new process of leaching zinc oxide dust by ozone oxidation in a sulfuric acid system was studied. The main factors affecting the leaching rate, such as ozone time, leaching temperature, initial acidity, leaching time, and liquid/solid mass ratio, were comprehensively investigated. The results show that leaching efficiency depends on all the above factors. The optimum conditions for leaching Zn and Ge from zinc oxide dust are as follows: ozone time 10 min, leaching temperature 90 ℃, initial acidity 160 g/L, leaching time 60 min, and liquid/solid mass ratio 7:1. Under the optimum conditions, the leaching rates of Zn and Ge are 95.79% and 93.65%, respectively. The leaching rates of zinc and germanium in the ozone leaching are 4.05% and 10.49% higher than those of the atmospheric leaching, respectively. Therefore, it is determined that ozone in solution plays a key role in rapidly oxidizing sulfide and releasing encapsulated germanium. Sulfuric acid-ozone media can efficiently extract Zn and Ge from zinc oxide dust.     

Facile Synthesis of an Octagermacubane with Two Three-Coordinate Germanium(0) Atoms and its Unique Radical Anion

Thermolysis of a 1 : 1 mixture of tris(di-tert-butylmethylsilyl)germane 9 and bis(di-tert-butylmethylsilyl)germane 17 at 100 °C produces unexpectedly octagermacubane 18 , having two 3-coordinate Ge⁰ atoms (40 % yield). 18 was characterized by X-ray crystallography and it is a singlet biradical (according to DFT quantum mechanical calculations and the absence of an EPR signal). Reactions of 18 with CH₂Cl₂ and H₂O yield the novel dichloro-octagermacubane 24 and hydroxy-octagermacubane 25 , respectively. Reduction of 18 with tBuMe₂SiNa in THF produces an isolable octagermacubane radical anion 26-Na . Based on X-ray crystallography, EPR spectroscopy and DFT quantum mechanical calculations, 26-Na is classified as a Ge-centered radical anion.     

Relative Stability of Multiple Bonds between Germanium and Stibium. A Theoretical Study

Substituent effects on the potential energy surface of XGeSb (X=H, Li, Na, BeH, MgH, BH₂, AlH₂, CH₃, SiH₃, NH₂, PH₂, OH, SH, F, and Cl) were investigated by using B3LYP/Def2‐TZVP, B3PW91/Def2‐ TZVPP CCSD (T)//B3LYP/Def2‐TZVP methods. The isomers include structures with formal double (Ge=SbX) and triple (Xge=Sb) bonds to germanium‐stibium, so a direct comparison of these types of species is possible. Our model calculations indicate that electropositively substituted Ge=SbX species are thermodynamically and kinetically more stable than their isomeric Xge=Sb molecules. Moreover, the theoretical findings suggest that only the organic substitutions (such as CH₃) can make triply bonded Xge=Sb molecule more stable than the doubly bonded Ge=SbX species.     

Structural Evolution and Electronic Properties of Au2Gen-/0 (n=1-8) Clusters: Anion Photoelectron Spectroscopy and Theoretical Calculations

Investigating the structures and properties of Au-Ge mixed clusters can give insight into the microscopic mechanisms in gold-catalyzed Ge films and can also provide valuable information for the production of germanium-based functional materials. In this work, size-selected anion photoelectron spectroscopy and theoretical calculations were used to explore the structural evolution and electronic properties of Au₂Ge_n^-/0 (n=1-8) clusters. It is found that the two Au atoms in Au₂Ge_n^-/0 (n=1-8) showed high coordination numbers and weak aurophilic interactions. The global minima of Au₂Ge_n^- anions and Au₂Ge_n neutrals are in spin doublet and singlet states, respectively. Au₂Ge_n^- anions and Au₂Ge_n neutrals showed similar structural features, except for Au₂Ge₄^-/0 and Au₂Ge₅^-/0. The C_2v symmetric V-shaped structure is observed for Au₂Ge₁^-/0, while Au₂Ge₂^-/0 has a C_2v symmetric dibridged structure. Au₂Ge₃^-/0 can be viewed as the two Au atoms attached to different Ge-Ge bonds of Ge₃ triangle. Au₂Ge₄^- has two Au atoms edge-capping Ge₄ tetrahedron, while Au₂Ge₄ neutral adopts a C_2v symmetric double Au atoms face-capping Ge₄ rhombus. Au₂Ge_5-8^-/0 show triangular, tetragonal, and pentagonal prism-based geometries. Au₂Ge₆ adopts a C_2v symmetric tetragonal prism structure and exhibits σ plus π double bonding characters.     

Design and fabrication of multi-layers infrared antireflection coating consisting of ZnS and Ge on ZnS substrate

We have designed, fabricated and characterized a multi-layers antireflection coating on multispectral ZnS substrate, suitable for the infrared range of 8–12 μm. The 4-layers coating (Ge/ZnS/Ge/ZnS) with optimized thicknesses was fabricated by PVD technique and studied by FTIR, nanoindentation and AFM. From FTIR spectroscopy it was found that, in the wavelength range of 8–12 μm, the average transmittance of the double-side coated sample increases by about 26% and its maximum reaches about 98%. To improve the mechanical hardness, a bilayer of Y₂O₃/carbon was deposited on the coating. Nanoindentation test shows that the coating enhances the mechanical properties. The final coating have successfully passed durability and environmental tests.