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One of the most widely used active materials for phase-change memories (PCM), the ternary stoichiometric compound Ge 2 Sb 2 Te 5 (GST), has a low crystallization temperature of around 150 ° C. One solution to achieve higher operating temperatures is to enrich GST with additional germanium. This alloy crystallizes into a polycrystalline mixture of two phases, GST and almost pure germanium. In a previous work [R. Bayle et al., J. Appl. Phys. 128, 185 101 (2020)], this crystallization process was studied using a multi-phase field model (MPFM) with a simplified thermal field calculated by a separate solver. Here, we combine the MPFM and a phase-aware electrothermal solver to achieve a consistent multi-physics model for device operations in PCM. Simulations of memory operations are performed to demonstrate its ability to reproduce experimental observations and the most important calibration curves that are used to assess the performance of a PCM cell. [ABSTRACT FROM AUTHOR]

The unique structure of van der Waals materials facilitates a robust mechanism for precise control of physical properties. In this study, we present a comprehensive analysis based on the intercalation of organometallics to modulate the optoelectronic behavior of two-dimensional germanium sulfide (GeS). Advanced computational exploration reveals significant and tunable features in the intercalated material. Additionally, the weak chemical interactions between organometallics and GeS support the electric-field-mediated drift and charge–discharge processes in intercalants. Controlling the concentration of organometallics in this manner enables the dynamic emergence of novel characteristics post-intercalation. These include flatbands near the Fermi level, significant enhancement of carrier mobility, and a magnetic ground state that is atypical for pristine GeS. Our findings demonstrate that organometallic intercalation offers a powerful strategy for tailoring the optoelectronic and magnetic characteristics of GeS, paving the way for harnessing emerging features for applications in next-generation devices. [ABSTRACT FROM AUTHOR]

Hybrid organic–inorganic perovskite solar cells have attracted significant attention in the field of optoelectronics due to their exceptional photovoltaic and optoelectronic properties. Although lead (Pb)-based perovskites exhibit the highest power conversion efficiencies, concerns about their toxicity and environmental impact have prompted significant research activities to explore alternative compositions. In this regard, a special emphasis has been devoted to tin (Sn) and germanium (Ge) based perovskites. In order to reveal the full potential of Sn–Ge based perovskites, we computationally screened perovskites with a general formula of A 0.5 A 0.5 ′ S n y G e 1 − y X 3 (y = 0.00, 0.25, 0.50, 0.75, 1.00) at the density functional theory level, particularly using the HSE06 hybrid functional. By using 18 A/A′-cations, four X-anions, and five different y compositions, a total of 7695 perovskites in cubic (C), orthogonal (O), and tetragonal (T) phases were considered, and the most promising ones have been filtered out based on their formation energy and bandgap. More specifically, 596, 525, and 542 C-, O-, and T-phase perovskites have been identified with a HSE06 bandgap range of 1.0–2.0 eV. While the Sn1.00Ge0.00 composition was dominated for both C- and O-phases, for the T-phase, a higher number of promising perovskites were obtained with the Sn0.75Ge0.25 composition. It has also been found that Sn-rich perovskites exhibit more favorable bandgap characteristics compared to Ge-rich ones. FA, MS, MA, K, Cs, and Rb are the most favored A/A′-cations in these promising perovskites. Moreover, I− overwhelmingly prevails as the dominant anion. Further experimental validation may uncover the true capabilities and practical applicability of these promising perovskites. [ABSTRACT FROM AUTHOR]

We introduce a data-driven potential aimed at the investigation of pressure-dependent phase transitions in bulk germanium, including the estimate of kinetic barriers. This is achieved by suitably building a database including several configurations along minimum energy paths, as computed using the solid-state nudged elastic band method. After training the model based on density functional theory (DFT)-computed energies, forces, and stresses, we provide validation and rigorously test the potential on unexplored paths. The resulting agreement with the DFT calculations is remarkable in a wide range of pressures. The potential is exploited in large-scale isothermal-isobaric simulations, displaying local nucleation in the R8 to β-Sn pressure-induced phase transformation, taken here as an illustrative example. [ABSTRACT FROM AUTHOR]

Transient reflectivity measurements are used to probe the strain waves induced by ultrashort laser pulses in bulk [100] germanium. The measurement signals are compared to purely analytical model functions based on the known material parameters for germanium. The modeling includes (i) a derivation of analytical solutions to the wave equation for strain waves coupled to the diffusion equation for heat and charge carriers and (ii) an expression for the impact on reflection coefficients that are caused by perturbations to the dielectric function but extended to cover a non-isotropic, uniaxial dielectric tensorial form. The model is held up against transient reflectivity measurements with an s- and a p-polarized probe and with a probe wavelength in the range of 502–710 nm. Excellent agreement is found when comparing the oscillatory shape of the measurement signals to the models. As for the magnitude of the oscillations, the models reproduce the overall trends of the experiment when using the previously published values for the elasto-optical tensor measured under static strain. [ABSTRACT FROM AUTHOR]

Two-dimensional germanium is considered a promising new channel material to replace silicon owing to its lower effective mass and larger electron–hole mobility. To investigate the transport characteristics of single-layer germanane transistors with gate lengths (Lg) below 5 nm, we utilize an ab initio quantum transport methodology. It was found that the n-type germanane transistors having Lg of 3 and 5 nm satisfy the International Technology Roadmap for Semiconductors (ITRS) requirements for the on-state current (Ion), effective delay time, and power-delay products of high-performance (HP) devices. Notably, by introducing a negative capacitive (NC) dielectric layer, the p-type germanane transistor having an Lg of 5 nm is almost able to meet the ITRS demands for HP devices. Despite reducing the gate length to 2 nm through the incorporation of the NC dielectric layer, the on-state currents for both n-type and p-type still satisfy approximately 80% of the ITRS standard. Therefore, monolayer germanane presents promising potential as a channel material in a sub-5 nm scale for HP applications. [ABSTRACT FROM AUTHOR]

Germanium has received increased research interest for use in next-generation CMOS technology as its high carrier mobilities allow for enhanced device performance without further device scaling. Fabrication of high-performance NMOS Ge devices is hindered by high diffusivity and low activation of n-type implanted dopants. While the high solid solubility of P in Ge makes it an ideal dopant, its diffusion mechanism is poorly understood and results in heavy tradeoffs between implanted dopant diffusion and electrical activation. In this study, we demonstrate the suppression of in-diffusion of implanted P via a co-implantation with Ar. Diffusivity of implanted P species and their activation is investigated over a wide range of annealing temperatures and times. P diffusion was explored by secondary-ion-mass-spectrometry and the diffusivity of P was extracted by solving the 2D diffusion equation using the Crank–Nicolson method, and the dopant electrical activation was extracted from the Hall effect measurements. The co-implantation of P with Ar entirely suppresses P in-diffusion up to annealing temperatures as high as 700 °C but at the cost of its reduced electrical activation. Extracted diffusivity reveals a highly correlated exponential relationship with annealing. P activation energy was extracted from Arrhenius behavior. A 450 °C/10 min annealing of P implant shows negligible in-diffusion of P with the activation as high as 70%. RTA processing of the Ar/P co-implanted sample at 750 °C for 1 min results in a negligible P in-diffusion and an electrical activation of 20%. [ABSTRACT FROM AUTHOR]

The capacities of various interatomic potentials available for elemental germanium, with the scope to choose the potential suitable for the modeling of germanene (2D germanium) allotropes,f were investigated. Structural and mechanical properties of the flat, low-buckled, trigonal dumbbell, and large honeycomb dumbbell single-layer germanium (germanene) phases, were obtained using the density functional theory and molecular statics computations with Tersoff, modified embedded atom method, Stillinger–Weber, environment-dependent interatomic potential, ReaxFF, and machine-learning-based interatomic potentials. A systematic quantitative comparative study and discussion of the findings are given. [ABSTRACT FROM AUTHOR]

Ensuring high‐quality surface passivation is the key to realizing high‐performance self‐powered optoelectronic devices, as it significantly impacts carrier transport. 2D hexagonal boron nitride (hBN) exhibits exceptional material characteristics, including a wide bandgap, high dielectric constant, minimized dangling bonds, and high chemical stability, making it one of the most promising candidates for high‐quality passivation. Nevertheless, the passivation characteristics of hBN on Ge and their influence on self‐powered photodetection remain unexplored, as well as their effects on carrier recombination lifetime, interface defect density, and Schottky barrier height. In this study, the first demonstration of enhanced Schottky junction photodiode characteristics and the impact of the surface passivation on carrier lifetime and defect density using an hBN monolayer on Ge are presented. The characteristics of hBN/Ge with Al2O3/Ge are compared to demonstrate the superior passivation quality of hBN over conventional materials. These results highlight the significant potential of hBN as an effective passivation for optoelectronic device applications. [ABSTRACT FROM AUTHOR]

Oxyapatites A10(GeO4)6O2 (A – alkaline, rare‐earth elements) are considered promising materials for applications in solid‐state lighting and non‐contact thermometry. The temperature dynamics of the oxygen sublattice have a crucial influence on the luminescent properties of these optical hosts. Here, the structural evolution with temperature of germanates with the general formula ALa9(GeO4)6O2 (A – Li, Na, K, Rb) is investigated, using X‐ray and neutron powder diffraction methods. These compounds crystallize in space‐group P63/m. NPD experiments helped to determine the oxygen and alkaline metal positions. Thermally‐induced reentrant structural transitions relating to the oxygen in the apatite channel are discovered for the first time. In the example of Eu‐doped RbLa9(GeO4)6O2 and KLa9(GeO4)6O2, it is demonstrated that the luminescence of the Eu3+ ion is influenced by small changes in the crystal structure. [ABSTRACT FROM AUTHOR]

An eight‐channel local‐area‐network wavelength division multiplexing silicon photonic transceiver is designed within a 5 mm × 5 mm chip area. This integrated chip is composed of a set of perfectly vertical grating couplers, interleaved angled‐MMI wavelength division (de)multiplexers, silicon E‐O modulators, and germanium waveguide photodetectors. The multiplexer exhibits an IL of (4.5–5.8) dB and average crosstalk ≈−20 dB. Due to the limited bandwidth of the 2‐D GC, the IL of the demultiplexer is 5.17 dB at minimum, with a channel nonuniformity of 5.53 dB. The EO modulator and germanium waveguide PD exhibit 3‐dB bandwidths of 45 and 47 GHz, respectively. With a customized fiber array packaged, a back‐to‐back data transmission capacity of 1.56 and 1.42 Tb/s with BERs below the SD‐FEC limit is demonstrated for the transmitter and receiver, respectively. By connecting the transmitter and receiver, the dynamic performance of the transceiver chip is characterized, and the total data capacity of eight wavelength channels is 1.18 Tb/s. To show the advantage of transmission distance, 2 and 10 km SMF transmission experiments are also carried out. Through close integration with matched electronic circuits, the data capacity of this transceiver chip can be potentially boomed to 1.6 Tb/s. [ABSTRACT FROM AUTHOR]

The diaminoferrocene derivative fc[NH(BMes2)]2 (1H2; fc=1,1'‐ferrocenylene, Mes=mesityl) was prepared from fc(NH2)2 and Mes2BCl and used for the preparation of the N‐heterocyclic tetrylenes fc{[N(BMes2)]2E} (1E, E=Ge, Sn) via the sodium amide fc[NNa(BMes2)]2 (1Na2), which was obtained from 1H2 and NaN(SiMe3)2. 1H2 is inert towards LiN(SiMe3)2 or nBuLi. Its reaction with nBuLi in the presence of TMEDA afforded the TMEDA‐coordinated lithium amide 1Li2(TMEDA)2. Crystallisation of 1Na2 from THF furnished the adduct 1Na2(THF)3. The reaction of 1Na2 with Me3SiCl afforded 1(SiMe3)2. Attempts to obtain the thiourea fc{[N(BMes2)]2C=S} (1C=S) from 1Na2 and Cl2C=S were not successful. 1C=S is accessible from fc(NH3)Cl2, which is transformed to fc[(NH)2C=S] (2) by reaction with Cl2C=S and NEt3 (4 equiv.), followed by conversion of 2 to fc{[N(SiMe3)]2C=S} (3) with Me3SiCl and NEt3 (2 equiv.) and subsequent reaction of 3 with Mes2BCl. All new compounds except 1Na2 and 2 were structurally characterised by single‐crystal X‐ray diffraction. The N‐boryl substituents of 1E compete efficiently with the EII atom for nitrogen π‐donation, causing comparatively long EII−N bonds and small EII bond angles. 1C=S contains a four‐membered BNCS ring due to intramolecular adduct formation involving the Lewis basic S atom and a Lewis acidic B atom. [ABSTRACT FROM AUTHOR]

In the present work we have investigated the stability, CO poisoning tendency and HOR and ORR activities of small-sized monometallic Pt and bimetallic PtGe nanoclusters deposited on a series of 2D materials. By means of global minima search and mechanistic studies at the density functional theory (DFT) level with continuum implicit solvent, a screening of size, composition and support material has been carried out to obtain the optimal catalyst compositions that may boost the catalytic performance. Alloying and support effects work in two directions. On the one hand, the support increases the stability and modifies the electronic structure of the cluster via metal-support interaction. On the other hand, the cluster can change the electronic properties and catalytic activity of the support, which can be modulated with its size and composition. In addition, the 2D support assists pure Pt clusters in reducing the propensity to undergo CO poisoning, which can be further reduced by Ge alloying. This effect can be exploited to the point that the interaction with CO is not even favorable, as in Pt 5 Ge 5 /germanene, thus completely inhibiting the CO poisoning on the catalyst. Regarding the catalytic activities, all the catalysts studied in this work yield too high overpotentials for the ORR in acidic conditions, due to the presence of too oxophilic active sites which results in the overbinding of oxygenated species. However, the combination of Ge alloying and 2D support yield remarkable results in the HOR performance. The simultaneous tailoring of catalyst composition and support is demonstrated to be an effective strategy to successfully adjust the catalytic properties. [Display omitted] • This article studies the activity of Pt(Ge) clusters supported on 2D materials. • 2D materials enhance significantly the stability of monometallic clusters. • Combination of 2D material and Ge alloying drastically reduces CO poisoning. • Combination of 2D material and Ge alloying yields too oxophilic active sites for ORR. • Combination of 2D material and Ge alloying optimizes HOR performance. [ABSTRACT FROM AUTHOR]

This work presents the advancement of lead‐free tin perovskite photodiodes in terms of their photodetection and air stability by incorporating germanium (Ge) and ethylenediamine (EDA) to formamidinium tin iodide (FASnI3). EDA0.01FA0.98SnI3:Ge‐based photodiodes demonstrate a significantly improved specific detectivity (1.6 × 1012 Jones at −0.1 V), cut‐off frequency (6.6 × 105 Hz), response speed (0.53 µs), and signal‐to‐noise ratio (45 dB) compared with control devices. The superior performance is attributed to the stronger Ge─I bond, the passivation of Sn2+ and I– vacancies by smaller Ge2+ ions, the promotion of a fully 3D perovskite structure, the elevation of the conduction band energy level, and the formation of a protective GeO layer. Various film analyses, including X‐ray photoelectron spectroscopy, UV photoelectron spectroscopy, density functional theory, as well as device testing using time‐of‐flight secondary ion mass spectrometry and voltage‐dependent admittance, support and explain the mechanisms behind the enhancements. Ge‐ and EDA‐incorporated photodiodes exhibit excellent air stability, as evidenced by the time‐dependent ultraviolet visible spectra and the considerably high certified power conversion efficiency without encapsulation in air, demonstrating their potential for practical applications. The obtained photodetection performance is highest among the published lead‐free tin‐based perovskite photodetectors, presenting a monumental progress from the previous report of the same group. [ABSTRACT FROM AUTHOR]

Hole-based spin qubits in strained planar germanium quantum wells have received considerable attention due to their favorable properties and remarkable experimental progress. The sizeable spin-orbit interaction in this structure allows for efficient qubit operations with electric fields. However, it also couples the qubit to electrical noise. In this work, we perform simulations of a heterostructure hosting these hole spin qubits. We solve the effective mass equations for a realistic heterostructure, provide a set of analytical basis wavefunctions, and compute the effective g-factor of the heavy-hole ground state. Our investigations reveal a strong impact of highly excited light-hole states located outside the quantum well on the g-factor. We find that sweet spots, points of operations that are least susceptible to charge noise, for out-of-plane magnetic fields are shifted to impractically large electric fields. However, for magnetic fields close to in-plane alignment, partial sweet spots at low electric fields are recovered. Furthermore, sweet spots with respect to multiple fluctuating charge traps can be found under certain circumstances for different magnetic field alignments. This work will be helpful in understanding and improving the coherence of germanium hole spin qubits. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) and the antioxidant germanium (Ge) are promising tools for boosting bioactive compound synthesis and producing healthier foods. However, their combined effect remains unexplored. This study demonstrates the synergistic impact of AMF and Ge on the growth, metabolite accumulation, biological activities, and nutritional qualities of Spinacia oleracea L. (spinach), a globally significant leafy vegetable. Individually, Ge and AMF increased biomass by 68.1% and 22.7%, respectively, while their combined effect led to an 86.3% increase. AMF and Ge also improved proximate composition, with AMF–Ge interaction enhancing crude fiber and mineral content (p < 0.05). Interestingly, AMF enhanced photosynthesis-related parameters (e.g., total chlorophyll) in Ge treated plants, which in turn increased carbohydrate accumulation. This accumulation could provide a route for the biosynthesis of amino acids, organic acids, and fatty acids, as evidenced by increased essential amino acid and organic acid levels. Consistently, the activity of key enzymes involved in amino acids biosynthesis (e.g., glutamine synthase (GS), methionine biosynthase (MS), lysine biosynthase (LS)) showed significant increments. Furthermore, AMF improved fatty acid levels, particularly unsaturated fatty acids in Ge-treated plants compared to the control. In addition, increased phenylalanine provided a precursor for the production of antioxidants (e.g., phenols and flavonoids), through the action of the enzyme phenylalanine ammonia-lyase (PAL), resulting in improved antioxidant activity gains as indicated by FRAP, ABTS, and DPPH assays. This study is the first to show that Ge enhances the beneficial effect of AMF on spinach, improving growth and nutritional quality, with promising implications for agricultural practices. [ABSTRACT FROM AUTHOR]

We have demonstrated a unique reductive coupling of 4‐iodophenyl isocyanide, facilitated by a perimidine‐based N‐heterocyclic germylene (NHGe), which yields a bis‐spirogerma compound featuring simultaneous C−C and C−N bond formation. This reaction, which leads to the oxidation of germanium from +2 to +4, represents a significant departure from previously documented isocyanide‐germylene interactions. The product exhibits extensive conjugation across its bicyclic C4Ge2N2 framework, conferring distinct photophysical properties, including prominent orange luminescence in both solution and solid states. The photophysical properties are supported by the TD‐DFT calculations confirming an n→π* transition. The potential application of this compound in optoelectronic devices, particularly as a hole transport layer in PbS quantum dot solar cells, is also explored, with promising preliminary results. [ABSTRACT FROM AUTHOR]

Inorganic semiconductor‐based nano/micro‐membranes are of great interest and can be used as active materials for high‐performance and flexible electronics, due to their unique and stable physical or chemical properties. However, the creation of high‐quality and single‐crystalline semiconducting membranes, particularly germanium (Ge) membranes, remains a significant challenge. In this study, a wet etching approach is developed to thin bulk Ge into soft Ge membranes, which are further used to fabricate flexible and stretchable photodetectors. The thickness of the obtained Ge membranes can be precisely controlled, with a minimum thickness of ≈1.6 µm. Investigations on the surface morphology, surface chemical composition, and Raman shifts indicate that the prepared Ge membranes are single‐crystalline and suitable for the following device fabrication. As an example, flexible and stretchable Ge photodetectors, of which the stretchability is realized by a meshed‐structure design, are demonstrated. Bending (with a minimum radius of 4 mm and a bending cycle of 10 000 times) and stretching (with a stretching strain of up to 10%) tests result in negligible variations in the device performance, revealing good flexibility, and stretchability, as well as the significant potentials of the prepared Ge membranes as candidates for flexible electronics. [ABSTRACT FROM AUTHOR]

The Centers for Disease Control and Prevention (CDC) Radiation Laboratory's primary mission is to provide laboratory support for an effective and efficient response to public health radiological emergencies. The laboratory has developed methods for several radiological threat agents, including Iridium-192 (Ir-192). Ir-192 can be analyzed via its gamma energy through analytical methods such as High Purity Germanium (HPGe) and its beta energy through Liquid Scintillation Counting (LSC). In this work, we present and compare HPGe and LSC rapid response methods for Ir-192 quantification. Both methods show the reasonable results and can be used in emergency situations. [ABSTRACT FROM AUTHOR]

Black germanium (Ge) exhibits exceptional light absorption, holding significant promise for optoelectronic applications. However, achieving self‐powered photodetection performance in black Ge is challenging due to its high surface recombination rate. Herein, this challenge is addressed by demonstrating self‐powered Graphene (Gr)/black‐Ge Schottky photodiodes, achieved through simultaneous nanotexturing and high‐quality self‐passivation. This approach involves utilizing reactive ion etching with Cl2 and BCl3 to achieve Cl‐passivated black Ge. Optical analysis reveals excellent optical characteristics in both Cl2‐treated and BCl3‐treated samples, including a high aspect ratio of 1.9 and a low reflectance of 1.5%. Notably, the Cl2‐treated black Ge exhibits a higher carrier lifetime of 20.4 µs compared to the 11.7 µs lifetime of the BCl3‐treated black Ge, attributed to the self‐passivation induced by Cl2 plasma, effectively mitigating defects. Surface composition analysis further confirms the substantial role of Cl in passivation. Significantly, these improved properties translate into notable advancements in device performance, including an enhancement in responsivity from 21 to 276 mA W−1 when compared to planar Gr/Ge devices. These findings underscore the potential of Cl2 RIE for developing high‐performance Ge‐based optoelectronic devices. [ABSTRACT FROM AUTHOR]

In this study, two new structures are proposed for reverse-conducting insulated gate bipolar transistors (RC-IGBT) that effectively prevent snapback by relocating the N-collectors and utilizing silicon–germanium in the collector region of each device. The forward mode of the proposed structures shows IC− VC characteristics without snapback, since the position of the N-collector is changed to prevent electron extraction. In the reverse mode, the silicon–germanium induces currents through tunneling and impacts the ionization mechanisms. Importantly, the proposed structures generate a stable current value even if there are errors in the length of the N-collector during ion implantation, which enhances the reliability of the device. In addition, the proposed structures exhibit similar values for the breakdown voltage at around 700 V and the turn-on and turn-off losses when compared to the conventional RC-IGBT. Thus, this paper improves the reliability of RC-IGBTs by mitigating the snapback effect while maintaining their unique electrical properties. [ABSTRACT FROM AUTHOR]

The research for wurtzite‐type ternary nitride semiconductors containing earth abundant elements with a stoichiometry of 1 : 1 : 2 was focused on metals like Mg or Zn, so far. The vast majority of these Grimm–Sommerfeld analogue compounds crystallize in the β‐NaFeO2 structure, although a second arrangement in space group Pmc21 is predicted to be a viable alternative. Despite extensive theoretical and experimental studies, this structure has so far remained undiscovered. Herein, we report on BeGeN2 in a Pmc21 structure, synthesized from Be3N2 and Ge3N4 using a high‐pressure high‐temperature approach at 6 GPa and 800 °C. The compound was characterized by powder X‐ray diffraction (PXRD), solid state nuclear magnetic resonance (NMR), Raman and energy dispersive X‐ray (EDX) spectroscopy, temperature‐dependent PXRD, second harmonic generation (SHG) and UV/Vis measurements and in addition also compared to its lighter homologue BeSiN2 in all mentioned analytic techniques. The synthesis and investigation of both the first beryllium germanium nitride and the first ternary wurtzite‐type nitride crystallizing in space group Pmc21 open the door to a new field of research on wurtzite‐type related structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coal ash is an important source of germanium, a crucial resource in modern society. • A coal gasification ash can be used both as germanium source and as building material. • An integrated valorization process for a real coal gasification fly ash is shown. • A more circular and sustainable recycling alternative for this waste is presented. • Better waste management option for coal gasification plants and old ash deposits. A Circular Waste Management alternative is considered in this paper in which a complete ash valorization process is proposed for an Integrated Gasification with Combined Cycle fly ash, trying to extract maximum value from this waste before it is discarded. In the paper, germanium, a scarce resource vital in our modern society, is first extracted from fly ash using water, with an extraction yield of 85%, and subsequently, the leached fly ash is used in the manufacture of fire-resistant boards containing 60% ash, thereby avoiding its disposal in a landfill. The potential environmental impact caused by the two stages of the process was analyzed, and the final effluent was considered to achieve a zero-discharge objective. This paper contributes to the development of a more sustainable management alternative for an industrial waste produced in increased amounts and provides the basis for a symbiotic coupling relationship among various industrial sectors. [ABSTRACT FROM AUTHOR]

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Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the countercurrent leaching process of neutral leaching and acid leaching in traditional zinc hydrometallurgy process, a small part of copper and most of germanium in the acid leaching solution will precipitate into the leaching residue when the acid leaching solution returns to the neutral leaching process, resulting in low recovery of copper and failure of direct separation and enrichment of germanium. Focusing on the separation and enrichment of copper and germanium in acid leaching solution of zinc calcine, the separation behavior of copper and germanium in the process of directly copper replacement and germanium neutralization precipitation of acid leaching solution was studied. The experimental results show that higher amount of iron powder and lower pH value will cause coprecipitation of copper and germanium in the acid leaching solution. Under the conditions of the temperature of 70 °C, iron powder stoichiometric addition of 1.2, time of two hours, pH value of 1.5-2.0, and reaction time of 20 minutes, the precipitation rate of germanium and copper is 2.51% and 96.53% respectively, which realizes effective separation of copper and germanium in solution. The arsenic in solution is co-precipitate wth copper. The main phases in the cementation products are Cu3As and Cu2O, and the mass fraction of copper in replacement precipitate is 58.02%. Under the condition of H2O2 dosage of 5 mL/L, temperature of 70 °C, time of 2.5 hours, and end point pH value of 5.0-5.2, the content of copper, iron and germanium in the neutralization solution is 16.52, 1.39 and 0.43 mg/L, respectively, which meets the requirements of subsequent purification. The neutralization residue is enriched with 2 501.40 g/t of germanium, which can be used as raw material for recovery of germanium. [ABSTRACT FROM AUTHOR]

Intense long‐wave infrared (LWIR) femtosecond pulses within the 8−14 µm atmospheric window present an array of applications, such as in strong‐field physics, ultrafast nonlinear spectroscopy, and self‐guided atmospheric propagation. However, the realization of an LWIR source capable of delivering millijoule‐class energy, few‐cycle duration, and kHz repetition rate concurrently remains challenging. Here, such an LWIR source via the combination of different nonlinear parametric processes is reported, driven by a 1 kHz Yb:YAG thin‐disk laser. The system comprises two parallel multi‐cycle optical parametric chirped‐pulse amplifiers (OPCPAs) operating at 2.3 and 3.1 µm, respectively, alongside a stage of ZnGeP2‐crystal‐based difference‐frequency generation (DFG). The resulting 9 µm DFG pulses have a record energy of 0.21 mJ, a 3‐cycle duration, a 1 kHz repetition rate, and long‐term energy stability. The simultaneous output of three synchronized intense lasers at short‐wave infrared (2.3 µm), mid‐wave infrared (3.1 µm), and LWIR (9 µm) renders the source particularly appealing for multicolor ultrafast applications. [ABSTRACT FROM AUTHOR]

This study uses density functional theory to investigate boron nitride nanoclusters functionalized with amino acids for enhanced binding of bisphenols A (BPA) and Z (BPZ) to mimic the estrogen-related receptor gamma. Three categories of nanoclusters were examined: pristine B12N12, and those which were germanium-doped for boron or nitrogen. The study reveals that hydrogen bonding patterns and molecular stability are significantly influenced by the type of functional group and the specific amino acids involved. Ge-doping generally enhances the binding stability and spontaneity of the nanocluster–amino acid–bisphenol complexes, with Glu 275 emerging as the most stable binding site. The analysis of electronic properties such as energy gap, ionization potential, electron affinity, and chemical hardness before and after bisphenol binding indicates a general trend of increased reactivity, particularly in Ge-doped nanoclusters. The findings highlight the potential of these nanocluster composites in applications requiring high reactivity and electron mobility, such as pollutant removal and drug delivery. [ABSTRACT FROM AUTHOR]

Strain engineering serves as an effective method for optimizing electronic and optical properties in semiconductor devices, with applications including the enhancement of optical emission in Ge and GeSn‐based devices, improvement of carrier mobility, and second harmonic generation in silicon photonics structures. Current methods for deformation characterization in semiconductors, such as X‐ray diffraction and Raman spectroscopy, often require bulky and expensive setups and are limited in vertical resolution. Consequently, techniques capable of measuring lattice strain while overcoming these drawbacks are highly desirable. This study proposes a proof of concept for a cost‐effective, compact, fast, and non‐destructive approach to probe non‐uniform strain fields and additional material properties by exploiting the bulk photovoltage effect. The method is benchmarked with an array of silicon nitride stripes deposited under varying pressure conditions on a germanium substrate. Initially, their surface strains are verified through Raman spectroscopy. The deformations are replicated in a finite element method platform by integrating mechanical simulations with deformation potential theory, thereby estimating the band edge energy landscape. Finally, the study discusses the theoretical behavior of the photovoltage signal, considering semiconductor properties, defects, doping, and deformation. The findings offer insights into the development of advanced techniques for strain and transport analysis in semiconductor materials. [ABSTRACT FROM AUTHOR]

Synthesis and structural characterization of a family of germanium‐dioxolene complexes with ditopic N‐donor ligands (L1‐L5) (L1=1,2‐bis(pyridin‐2‐ylmethylene)hydrazine L2=1,6‐bis‐(pyridin‐2‐yl)‐2,5‐diaza‐1,5‐hexadiene, L3=N,N‐bis(pyridin‐2‐ylmethylene)‐1,4‐benzenediamine, L4=N,N‐bis(pyridin‐2‐ylmethylene)‐(biphenyl)‐4,4‐diamine, L5=2,2’‐azopyridine) is reported. The reaction of germanium bis‐catecholate with bridging ligands L1 – L4, differing by the nature of the linker between pyridine sites gives rise to dinuclear digermanium complexes (36Cat2Ge)2L1−4 (36Cat=dianion of 3,6‐di‐tert‐butylcatechol) 1–4 of DMAMD type (donor‐metal‐acceptor‐metal‐donor) with a charge transfer in the UV‐Vis region. In opposite, the interaction of the 36Cat2Ge with 2,2’‐azopyridine (L5) results in the two‐electron transfer from the donor 36Cat2− ligands to the azopyridine bridge forming stable open‐shell complex 5 [(36SQ)(36CatGe)]2(L5)2− (36SQ=radical‐anionic semiquinonate ligand). Molecular structures of compounds 3 and 5 were determined by single crystal X‐ray diffraction analysis. Electronic structures of complexes 1–5 were studied by means of DFT calculations. [ABSTRACT FROM AUTHOR]

In recent years, thermal imaging and sensing technologies have seen dramatic increases in usage for a range of applications. However, the material cost and manufacturing complexity of infrared optics remain a major barrier toward their democratization. Here, a solution‐processed plasmonic reflective filter (PRF) is presented as a scalable, disordered, and low‐cost thermal infrared (TIR) optic. The PRF selectively absorbs sunlight and specularly reflects TIR wavelengths, with a performance comparable to state‐of‐the‐art infrared optics made of materials like Germanium. Unlike the latter, however, the PRF is fabricated using low‐cost materials and a "dip‐and‐dry" chemical synthesis technique, which enables orders of magnitude lower manufacturing costs. The PRF's optical functionality and integration into infrared imaging systems are experimentally demonstrated. The chemical synthesis technique also affords exceptional spectral tuneability and material compatibility compared to traditional fabrication methods. The PRF's tuneable and broadband TIR yield can be augmented by inexpensive dielectric or polymeric filters to yield novel capabilities such as wide‐area ambient temperature surveys. Practically, the PRF represents a significant advance toward democratizing the benefits of thermal imaging and sensing. Scientifically, it represents a previously unexplored optical functionality of disordered materials, and a new direction for versatile chemical synthesis in designing optical components. [ABSTRACT FROM AUTHOR]

During the oxidation of SiGe regions, Si is preferably incorporated into the oxide, while Ge atoms accumulate at the SiGe side of the interface. Moreover, during oxidation of fin structures of Si/SiGe superlattices, Ge atoms diffuse from SiGe regions to Si regions along the oxide/SiGe interface, as recently reported. This surface diffusion can be used for the formation of Si nanowires surrounded by SiGe, and possibly for the fabrication of gate all‐around transistors. Herein, a new process simulation model is presented which describes SiGe oxidation and the diffusion of Ge atoms along the interface. During oxidation, Ge atoms can be trapped at the oxide/SiGe interface, diffuse along the interface, and be re‐emitted into the SiGe bulk. The model reproduces measured oxidation rates, the pileup of Ge atoms at the SiGe side of planar oxide/SiGe interfaces, the injection of self‐interstitials and the reduction of vacancies at oxidizing SiGe surfaces, and the recently reported diffusion of Ge atoms along the surface of fin structures made of Si/SiGe superlattices. [ABSTRACT FROM AUTHOR]

In this work, the integration of graphene nanoplatelets (GNPs) with amorphous germanium (Ge) substrates is explored. The optical properties were characterized using Variable-Angle Spectroscopic Ellipsometry (VASE). The findings of this study reveal a strong interaction between GNPs and amorphous germanium, indicated by a significant optical absorption. This interaction suggests a change in the electronic structure of the GNPs, implying that amorphous germanium could enhance their effectiveness in devices such as optical sensors, photodetectors, and solar cells. Herein, the use of amorphous germanium as a substrate for GNPs, which notably increases their refractive index and extinction coefficient, is introduced for the first time. By exploring this unique material combination, this study provides new insights into the interaction between GNPs and amorphous substrates, paving the way for the develop of high-performance, scalable optoelectronic devices with enhanced efficiency. [ABSTRACT FROM AUTHOR]

Germanium (Ge) is a critical raw material for emerging high-tech and green industries, resulting in considerable recent interest in understanding its distribution and geochemical behavior in ore deposits. In this contribution, the distribution of Ge and related trace elements in the Fule Pb-Zn(-Ge) deposit, South China, is investigated to reveal the distribution of Ge in the hydrothermal ores and during sulfide weathering, using multiple microanalytical techniques, including scanning electron microscopy, electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In the Fule MVT deposit, sphalerite (ZnS) is the most significant Ge-carrier relative to other sulfides, though the five recognized textural types of sphalerite display progressive depletion in Ge from the first sphalerite generation to the late one. In the early stage, sphalerite with fine-grained chalcopyrite inclusions has the highest Ge concentrations, probably accounting for a significant proportion of the total Ge. We interpret that high Ge concentrations in the early sphalerite may be attributable to high Cu activity in the mineralizing fluids. During oxidative weathering, Ge was redistributed from its original host, sphalerite, to the weathering product willemite (Zn2SiO4) rather than smithsonite (ZnCO3), with high levels of Ge (up to 448 μg/g) present in the willemite. The formation of abundant willemite largely prevents the dispersion of Ge during weathering. In principle, willemite-hosted Ge should be fully recoverable, and the Zn-silicate ores may, therefore, be a potential target to meet future demand. This study provides new information on how Ge behaves from sulfide- to weathering-stage in MVT systems, which directly impacts Ge mobility and deportment changes and the development of metallurgical strategies for Ge recovery. [ABSTRACT FROM AUTHOR]

Transparent amorphous germanium (a‐Ge) has emerged as a promising material for engineering nanostructures and metasurfaces, offering significant potential for enhancing the performance of photonic devices in the short‐wavelength infrared (SWIR) spectrum. Herein, the successful application of a‐Ge metasurfaces with a truncated pyramid profile to enhance the external quantum efficiency (EQE) of a digital alloy Al0.3InAsSb p–i–n photodiode across a broad‐wavelength range in the SWIR is presented. The experimental findings demonstrate a broadband enhancement in EQE. Two metasurface samples are designed to emphasize different‐wavelength ranges. Notably, 51% improvement in EQE at 1550 nm and 125% enhancement at 2000 nm is achieved. Finite‐difference time domain simulations show that the observed EQE improvement originates from the reduction of reflection and electromagnetic field enhancement. This study underscores the promising role of a‐Ge metasurfaces in advancing the capabilities of SWIR photodetectors. It lays the groundwork for further exploration in optoelectronic device enhancements. [ABSTRACT FROM AUTHOR]

Anode materials based on IV main group elements like Si, Ge, and Sn show great potential for lithium‐ion batteries (LIBs) due to their high specific capacity and low working potential. However, issues such as volume expansion and lattice pulverization hinder their practical usage. To address these issues for Ge, a novel F127 triblock polymer/acetylene black dual‐assisted strategy is proposed to achieve uniform dispersion of polycrystalline Ge, enabling the preparation of Ge@C nanocomposites via hydrogen reduction. The introduced F127 triblock polymer and acetylene black serves a dual purpose to enhance electrical conductivity and prevent Ge nanoparticles from agglomeration. When tested as anode material for LIBs, the Ge@C nanocomposites exhibit exceptional electrochemical performances, demonstrating a sustained specific discharge capacity of 780 mA h g−1 at 0.2 A g−1 after 100 cycles. Moreover, the capacity remains at 767 mA h g−1 even after 300 cycles at a higher current density of 0.5 A g−1. These enhanced lithium storage performances are attributed to the combined effects of well‐dispersed tiny Ge nanoparticles, uniform carbon coating, and an abundance of defects. These factors effectively mitigate the volume expansion and lattice pulverization of Ge nanoparticles and concurrently enhance their conductivity, leading to improved overall performance in LIBs. [ABSTRACT FROM AUTHOR]

Efficient p‐ and n‐type in situ doping of compressively strained germanium tin (Ge1‐xSnx) semiconductor epilayers, grown by chemical vapor deposition on a standard Si(001) substrate, is demonstrated. Materials characterization results reveal unusual impact of dopants manifesting via a pronounced reduction of Sn content in the epilayer, accompanied by an enhancement of the growth rate, due to increasing p‐type doping concentration. Furthermore, the opposite behavior for n‐type doping is observed, resulting in a less pronounced increase of Sn concentration and no effect on growth rate. Nevertheless, a very high density of electrically active holes up to ≈4 × 1020 cm−3 is obtained in p‐type doped Ge1‐xSnx epilayer resulting in the lowest resistivity of 0.15 mΩ cm among all in situ doped epitaxial and strained group‐IV semiconductors. Also, the metal‐to‐insulator transition in Ge1‐xSnx is experimentally demonstrated for doping levels above 1 × 1017 cm−3, which is substantially lower than in any group‐IV semiconductor, and theoretically predict it to be as low as ≈1 × 1017 cm−3. The findings enabled by the doping regime explored in this work can open novel prospects to engineer low resistivity contacts and charge current injection in applications covering next‐generation transistors, qubits, diodes, electrically driven light sources, sensors and hybrid quantum devices. [ABSTRACT FROM AUTHOR]

Germanium is reemerging as a prominent material in the semiconductor field, particularly for electronic applications, photonics, photovoltaics, and thermophotovoltaics. Its combination with III‐V compound semiconductors through epitaxial growth by metal‐organic vapor phase epitaxy (MOVPE) is instrumental and thus, the comprehension of the sequential stages in such epitaxial processes is of great importance. During the deposition of GaAs on p‐type Ge, the formation of n/p junctions occurs when As diffuses into Ge. It is found that this formation begins in the so‐called AsH3 preexposure where Ge substrate is first exposed to AsH3. Also important is the fact that both free carrier profiles and As profiles indicate that prolonged AsH3 preexposure times lead to deeper diffusion depths for the same process time. This effect is concomitant with the degradation of the Ge surface morphology, characterized by higher roughness as the AsH3 preexposure duration is extended. Unlike ion‐implanted As in Ge, which shows a quadratic dependent diffusivity, this MOVPE investigation using AsH3 indicates a linear relationship, consistent with Takenaka et al.'s MOVPE study using TBAs. The analysis of As profiles alongside simulations, with and without subsequent GaAs epitaxy, suggests the generation of Ge vacancies during the process, contributing to deeper As diffusion. [ABSTRACT FROM AUTHOR]

This letter focuses on the field-programmable gate array (FPGA) implementation of a Class A Middleton noise estimator, aiming to enhance its efficiency and performance. The inherent algorithm of the estimator undergoes strategic enhancements, leveraging median approximations. This endeavor leads to the development of a more streamlined and expeditious architecture. The research not only introduces the refined architecture but also conducts a comparative analysis of its attributes. The outcomes of this investigation show the benefits of algorithmic optimization, as the execution times achieved in hardware significantly surpass those attainable through software-based implementation. This underscores the practicality of the algorithmic refinement and also the notable advantages of the FPGA-based execution in terms of computational speed. [ABSTRACT FROM AUTHOR]

The article is devoted to lignite deposits of Zakarpattia, which contain germanium, in particular, the Bigan deposit and methods of extracting germanium from this deposit. Ukraine has coal deposits with industrial concentrations of germanium and industrial capacity for obtaining high-purity germanium. Until recently, this allowed the domestic germanium complex to be among the leaders of the world market. Unfortunately, now the production of germanium in Ukraine is suspended, and the processing of metal-bearing coal is carried out without obtaining the corresponding germanium concentrate. Ukrainian coal deposits, which are characterized by germanium metal content, are currently not used in full for their complex purpose. The state mineral balance of Ukraine as of January 1, 2024 includes 226 subsoil exploitation objects with estimated germanium reserves. Germanium in Ukraine is associated mainly with coal deposits of the Donetsk and Lviv-Volyn coal basins, where it is found as an accompanying component. Germanium is found in all coal beds of the Lower, Middle and Upper Carboniferous of Donbass, but the most productive beds are found in hard coal of the Middle Carboniferous. Germanium content in Donbas coal ranges from 0.3-1.3 g/t in anthracite to 3.8-9.2 g/t in low-metamorphosed coal grades D, DG, G; however, as a rule, only coking coal with an average content of germanium at the level of 4.5 g/t was once used to obtain this metal thanks to the processing of the corresponding concentrate, which was produced at the chemical plants of the coke-chemical plants of Ukraine using the technology of extracting germanium compounds from supertar water. The content of germanium in brown coal of the Dnieper basin is relatively low (1-2 g/t of ash). At the same time, in the Transcarpathian lignite basin, the main mass of which is small deposits confined to the deposits of the Ilnytsia world of the Neogene Chop-Mukachivska and Solotvyn depressions. Thus, the content of germanium in lignite of the Novoselytskyi deposit is up to 280 g/t, in the Bigan deposit - up to 1000 g/t. The Bigan deposit itself requires further research as one of the most promising lignite deposits in Germany. It is worth noting that germanium is found in significant quantities not only in brown coal (lignites), but also in carbonaceous clays, where the concentration of germanium reaches 200 g/t. The decisive factor in the distribution of germanium in the layers is the nature of the plant material from which this layer is composed. Based on the analysis of the results of the work carried out, the highest germanium content (over 1000 g/t) is confined to pure varieties of lignite, and especially weakly carbonized wood residues, the amount of which depends on the concentration of germanium in the formation as a whole. It is quite clear that germanium in lignites is associated with humic acids, forming organometallic compounds. This is confirmed by the fact that by treating lignite with a 1% ammonia solution, it is possible to obtain up to 98% germanium. Geological exploration work at the Bigan deposit was carried out intermittently from 1953 to 1969. In 1961-1965, search operations were carried out on an area of about 30 km². Total of 486 wells (87,000 cubic meters) have been drilled in the field and adjacent areas since the beginning of geological exploration. The preliminary exploration of the Bigan deposit was carried out using the results of the search and exploration works of 1961-1967, while technological studies of the lignites of this deposit were also carried out. As a result, a feasibility study was drawn up, the summary of which was reduced to the fact that the Bigan deposit is characterized by a relatively high content of germanium, which allows this deposit to be considered a large potential source of germanium. It is worth noting that in the 80s of the last century, a technology was developed for the industrial development of the Malobigan and Bigan deposits by burning lignite at the Uzhhorod TPP, followed by hydrometallurgical processing of ash and dust containing several kilograms of germanium per ton. It is important that in Transcarpathia, in addition to the above-mentioned deposits, there are 15 more unexplored, but promising germanium-bearing areas. It should be noted that the concomitant extraction of germanium is one of the ways to improve the economic indicators of the coal industry and the comprehensive use of lignite deposits of Zakarpattia. The set of works carried out allows judging on the basis of experimental data about rational ways of using germanium-bearing lignites of the Bigan deposit. [ABSTRACT FROM AUTHOR]

The article is devoted to lignite deposits of Zakarpattia, which contain germanium, in particular, the Bigan deposit and methods of extracting germanium from this deposit. Ukraine has coal deposits with industrial concentrations of germanium and industrial capacity for obtaining high-purity germanium. Until recently, this allowed the domestic germanium complex to be among the leaders of the world market. Unfortunately, now the production of germanium in Ukraine is suspended, and the processing of metal-bearing coal is carried out without obtaining the corresponding germanium concentrate. Ukrainian coal deposits, which are characterized by germanium metal content, are currently not used in full for their complex purpose. The state mineral balance of Ukraine as of January 1, 2024 includes 226 subsoil exploitation objects with estimated germanium reserves. Germanium in Ukraine is associated mainly with coal deposits of the Donetsk and Lviv-Volyn coal basins, where it is found as an accompanying component. Germanium is found in all coal beds of the Lower, Middle and Upper Carboniferous of Donbass, but the most productive beds are found in hard coal of the Middle Carboniferous. Germanium content in Donbas coal ranges from 0.3–1.3 g/t in anthracite to 3.8–9.2 g/t in low-metamorphosed coal grades D, DG, G; however, as a rule, only coking coal with an average content of germanium at the level of 4.5 g/t was once used to obtain this metal thanks to the processing of the corresponding concentrate, which was produced at the chemical plants of the coke-chemical plants of Ukraine using the technology of extracting germanium compounds from supertar water. The content of germanium in brown coal of the Dnieper basin is relatively low (1–2 g/t of ash). At the same time, in the Transcarpathian lignite basin, the main mass of which is small deposits confined to the deposits of the Ilnytsia world of the Neogene Chop-Mukachivska and Solotvyn depressions. Thus, the content of germanium in lignite of the Novoselytskyi deposit is up to 280 g/t, in the Bigan deposit – up to 1000 g/t. The Bigan deposit itself requires further research as one of the most promising lignite deposits in Germany. It is worth noting that germanium is found in significant quantities not only in brown coal (lignites), but also in carbonaceous clays, where the concentration of germanium reaches 200 g/t. The decisive factor in the distribution of germanium in the layers is the nature of the plant material from which this layer is composed. Based on the analysis of the results of the work carried out, the highest germanium content (over 1000 g/t) is confined to pure varieties of lignite, and especially weakly carbonized wood residues, the amount of which depends on the concentration of germanium in the formation as a whole. It is quite clear that germanium in lignites is associated with humic acids, forming organometallic compounds. This is confirmed by the fact that by treating lignite with a 1% ammonia solution, it is possible to obtain up to 98% germanium. Geological exploration work at the Bigan deposit was carried out intermittently from 1953 to 1969. In 1961–1965, search operations were carried out on an area of about 30 km². Total of 486 wells (87,000 cubic meters) have been drilled in the field and adjacent areas since the beginning of geological exploration. The preliminary exploration of the Bigan deposit was carried out using the results of the search and exploration works of 1961–1967, while technological studies of the lignites of this deposit were also carried out. As a result, a feasibility study was drawn up, the summary of which was reduced to the fact that the Bigan deposit is characterized by a relatively high content of germanium, which allows this deposit to be considered a large potential source of germanium. It is worth noting that in the 80s of the last century, a technology was developed for the industrial development of the Malobigan and Bigan deposits by burning lignite at the Uzhhorod TPP, followed by hydrometallurgical processing of ash and dust containing several kilograms of germanium per ton. It is important that in Transcarpathia, in addition to the above-mentioned deposits, there are 15 more unexplored, but promising germanium-bearing areas. It should be noted that the concomitant extraction of germanium is one of the ways to improve the economic indicators of the coal industry and the comprehensive use of lignite deposits of Zakarpattia. The set of works carried out allows judging on the basis of experimental data about rational ways of using germanium-bearing lignites of the Bigan deposit.

Numerical calculations and experimental approaches are used to examine the slip characteristics of 1064 nm laser ablated single crystal germanium. The ablation and cooling processes are used to investigate the influence of laser power density on the creation of the slip process. A 1064 nm continuous laser and a nanosecond laser were used to ablate single-crystal germanium samples, and the damage to the surface was seen using an optical microscope. The results demonstrate that raising the laser power density to 107 W/cm2 efficiently suppresses slip production during laser processing. [ABSTRACT FROM AUTHOR]

In this study, we fabricated laser-induced periodic surface structures (LIPSS) on a germanium surface through laser ablation in air using axicon and femtosecond (fs) pulses. This novel approach permitted the nanoscale material processing outcome refinement via an fs Bessel beam. Our investigations aimed at systematically understanding the formation of periodic structures under various experimental conditions, such as (i) different pulse energies ranging from 50 µ J to 1000 µ J at a constant scan speed and (ii) constant energy with different scan speeds (0.1–3 mm s−1). By adjusting the fluences and scan speeds, we were able to identify the parametric space and alter the periodicity of the low-spatial frequency LIPSS and high-spatial frequency LIPSS on germanium, which were analyzed using field emission scanning electron microscopy. An optimal LIPSS formation over a large area of germanium was achieved at an input energy of 250 µ J and a scan speed of 0.75 mm s−1. Additionally, we measured the contact angles of the Ge nanostructures (GeNSs) to demonstrate their hydrophobic nature and non-wetting properties, providing insights into the behavior of LIPSS. Subsequently, the GeNSs were coated with a ∼15 nm thick gold (Au) film using a thermal deposition method. Utilizing these, the surface-enhanced Raman spectroscopy (SERS) technique detected diverse analytes, such as tetryl (an explosive) at a concentration of 50 µ M and thiram (a pesticide) at 500 nM. The SERS enhancement factors for tetryl and thiram molecules on GeNSs coated with a 15 nm-thick Au layer were determined to be 2.5 × 104 and 4.2 × 105, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • A unique carbon coating Ge nanospheres with a cubic hollow structure (Ge@C) is controllably designed and synthesized by using low-cost GeO 2 as precursor. • The hollow Ge@C nanostructure not only provides abundant internal space to alleviate volumetric expansion of Ge, but also facilitates the transmission of Li+ and electrons. • The hollow Ge@C shows very superior lithium storage performance with enhanced Li+ adsorption ability and low Li+ diffusion energy barrier. • This work is a very important breakthrough for the development of high-performance Ge based anode for lithium ion batteries. Germanium based nanomaterials are very promising as the anodes for the lithium ion batteries since their large specific capacity, excellent lithium diffusivity and high conductivity. However, their controllable preparation is still very difficult to achieve. Herein, we facilely prepare a unique carbon coating Ge nanospheres with a cubic hollow structure (Ge@C) via a hydrothermal synthesis and subsequent pyrolysis using low-cost GeO 2 as precursors. The hollow Ge@C nanostructure not only provides abundant interior space to alleviate the huge volumetric expansion of Ge upon lithiation, but also facilitates the transmission of lithium ions and electrons. Moreover, experiment analyses and density functional theory (DFT) calculations unveil the excellent lithium adsorption ability, high exchange current density, low activation energy for lithium diffusion of the hollow Ge@C electrode, thus exhibiting significant lithium storage advantages with a large charge capacity (1483 mAh/g under 200 mA g−1), distinguished rate ability (710 mAh/g under 8000 mA g−1) as well as long-term cycling stability (1130 mAh/g after 900 cycles under 1000 mA g−1). Therefore, this work offers new paths for controllable synthesis and fabrication of high-performance Ge based lithium storage nanomaterials. [ABSTRACT FROM AUTHOR]

We have been interested in the differences between the properties of low-coordinated carbon compounds and their heavier homologues based on elements of group 14, e.g., Si and Ge. Fundamental research on the synthesis and characterization of divalent and multiply bonded compounds of heavier group 14 elements has led to a variety of isolated low-coordinated species of heavier group 14 elements that can replace transition metals in small-molecule transformations. We have focused on low-coordinated germanium compounds with double or triple bonds between germanium atoms, as well as germanium-containing aromatic compounds. Once isolated, the reactivity of these low-coordinated germanium compounds was examined with regard to small-molecule activation. In this account, the reactivity patterns of these compounds will be described. 1 Introduction 2 1,2-Dibromodigermenes and Bromogermylenes 3 Digermynes 4 1,2-Digermacyclobutene 5 1,3-Digerma-2-silaallene 6 Digerma-Aromatic Compounds 7 Germanium-Catalyzed Cyclotrimerization of Alkynes 8 Summary [ABSTRACT FROM AUTHOR]

Ab initio investigation of the spectroscopic constants, bond dissociation energies of germanium monohalides, germanium dihalides and their ionic systems, viz. GeX, GeX−, GeX+, GeX2, GeX2− and GeX2+ (X = F, Cl, Br and I) have been carried out using correlation consistent triple-zeta basis sets for F and Cl and similar triple-zeta basis sets with RECPs for Ge, Br and I atoms. Geometry and frequency of all the neutral and ionic systems of germanium halides are obtained using MP2, CCSD(T) and QCISD(T) methods. The energetics are obtained at the CCSD(T)//MP2, QCISD(T)//MP2, CCSD(T) and QCISD(T) levels. Electron affinity (EA) and ionization potential (IP) of the monohalides and dihalides are reported to be consistent with the data available in literature. The bond dissociation energies (BDEs) to various dissociation asymptotes for most of the ionic systems are to be reported new in literature. The BDEs of the neutral germanium dihalides GeX2 are calculated by using the BDEs of GeX2− and GeX2+ ions and EA and IP of the associated neutral systems. A good agreement is found between the calculated values and the data wherever available. The BDEs of GeX2 for higher halogen member are reported to be new in literature. The enthalpies of formation for atomization and ionization of the neutral GeX2 dihalides are also reported here. The enthalpies of ionization are reported first time in literature and found consistent with other group IV dihalides. The reported molecular properties may be helpful to understand the chemistry involved in the plasma-assisted fabrication process of the Ge-based modern microelectronic devices, as well as will serve as a future reference. [ABSTRACT FROM AUTHOR]