Ge System Research Articles

Modulating phononic landscapes: The role of silicon ion bombardment in tailoring Si/Si+Ge and SiO2/SiO2+Ge superlattices for advanced neutron superreflector applications

This study investigates the effects of silicon ion bombardment on the phononic properties of Si/Si+Ge and SiO2/SiO2+Ge superlattices to enhance neutron superreflector technology. Through precise ion implantation and Fourier Transform Infrared Spectroscopy (FTIR), we observed significant alterations in transverse and longitudinal optical phonon modes. The Si/Si+Ge system exhibited notable blueshifts and intensity changes, while SiO2/SiO2+Ge showed increased lattice disorder and peak broadening. These findings highlight ion bombardment's potential to optimize phononic landscapes for improved nuclear reactor safety and efficiency via advanced phonon engineering.

Performance enhancement of PPP/SINS tightly coupled navigation based on improved robust maximum correntropy kalman filtering

Extended kalman filter (EKF) is widely used to integrated navigation system of global navigation satellite system (GNSS) and strapdown inertial navigation system (SINS). However, non-Gaussian noise and the uncertainty of measurement noise can seriously reduce the performance of EKF, so it is difficult to obtain an optimal GNSS/INS integration solution. At present, non-Gaussian noise processing is still a difficult issue in filter research. In this paper, an adaptive and robust maximum correntropy extended kalman filter (MCEKF) method based on Cauchy kernel function is proposed to solve the above problem. Thanks to the excellent properties of Cauchy kernel function, the proposed method can effectively avoid filter faults and has better stability. However, the performance of MCEKF depends on the select of kernel bandwidth parameter, which is a difficult problem in the engineering application of MCEKF. In this paper, the switching kernel bandwidth algorithm is employed to adaptively estimate the kernel bandwidth parameter to solve the tradeoff between convergence rate and steady-state misalignment in the MCEKF algorithm under constant kernel bandwidth. Finally, the performance of the proposed algorithm is verified by two sets of vehicle-mounted precise point positioning (PPP) and SINS tightly coupled integration experiments in urban environment. The results show that compared with EKF, the proposed method can significantly improve the positioning accuracy, that is, the PPP/SINS positioning accuracy based on GE, GR and GRE system is improved by 25.1 %, 2.5 % and 17.0 % in D196 experiment, and 23.5 %, 16.5 % and 31.8 % in D107 experiment, respectively. The velocity and attitude accuracy of the two methods are similar. The velocity errors of all schemes can reach cm/s level. The roll, pitch and heading errors of navigation-grade inertial sensor are all less than 0.12 degree. The roll and pitch errors of MEMS are less than 1.0 degree, the heading error of the G, GE, GR, and GRE systems are 1.719, 1.464, 1.676, and 1.475 degree, respectively.

Structural stability, electronic, magnetic, thermoelectric, optical and thermodynamic properties of CoTiFeGe and Co2Fe0.25Mn0.75-xTixGe alloys

Density Functional Theory (DFT) calculations are performed using full potential linearized augmented plane wave (FP-LAPW) method to study CoTiFeGe and Co2Fe0.25Mn0.75-xTixGe (x = 0, 0.25, 0.50, 0.75) systems through GGA and mBJ-GGA formalisms. The lattice equilibrium optimization was conducted to determine the stable magnetic phase state of these systems. It was found that the systems exhibit stability in a ferromagnetic nature, with the exception of the Co2Fe0.25Mn0.75Ge compound, which displays ferrimagnetic behavior. Electronic band structures and density of states for our systems show a half-metallic character using mBJ-GGA, except the Co2Fe0.25Mn0.75Ge system, which exhibits metallic behavior. Furthermore, the studied systems adhere to the Slater-Pauling rule condition for half-metallicity of alloys Mtot = ZV-24. Optoelectronic properties have been analyzed using optical parameters, confirming semiconducting behavior. Optical reflections with minimal loss and the existence absorption are observed in the infrared and visible areas suggest that the studied systems are suitable for optoelectronic devices. Additionally, a comprehensive assessment of the thermodynamic properties of the systems was carried out to investigate their thermodynamical stability against temperature and pressure change. The transport properties of these systems were systematically investigated, revealing that our alloys present the poor thermoelectric matter.

Thermodynamic stability and ionic conductivity in lithium–germanium binary system

Lithium–germanium binary compounds are promising anode materials for secondary lithium-ion batteries due to their high capacity, low operating voltage, and high electronic conductivity of lithiated Ge. For their successful application in batteries, it is essential to know the temperature stability of different Li–Ge phases and the variation of their ionic conductivity depending on the operating temperatures of the batteries. This work aims to comprehensively study the thermodynamic stability and ionic conductivity in Li–Ge binary compounds using a combination of first-principle computations and machine-learning interatomic potentials. We calculated convex hulls of the Li–Ge system at various temperatures and a temperature–composition phase diagram was obtained, delineating stability fields of each phase. Our calculations show that at temperatures higher than 590 K, LiGe undergoes a I41/a–P4/mmm transition, which leads to a change in the ionic conductivity. We show that all stable and metastable Li–Ge compounds have high ionic conductivity, but LiGe and Li7Ge12 have the lowest lithium diffusion. Trajectories of diffusion and Ge arrangements depend on lithium concentration. Based on advanced theoretical approaches, this study provides insights for the development of Li–Ge materials in lithium-ion and lithium-metal battery applications.

Phase diagram of ternary Co–Fe–Ge system (I): Experimental

Co–Fe–Ge is an important material system for magnetic and catalyst applications. However, phase equilibria information of the Co–Fe–Ge ternary system is limited. Ternary Co–Fe–Ge alloys equilibrated at 950 °C were prepared. The microstructures, chemical compositions and crystal structure of each phase were determined. The phase equilibria isothermal section at 950 °C of the Co–Fe–Ge ternary system was then proposed. A continuous solid solution phase was formed between the Co5Ge3 and Fe5Ge3 phases and was labeled the β(Co,Fe)5Ge3 phase. There are five three-phase regions in the system at 950 °C. A wide α2 single-phase, and liquid phase regions with large composition ranges being confirmed at the Ge-poor and Ge-rich sides, respectively.

Unusual multiple magnetic transitions and anomalous Hall effect observed in antiferromagnetic Weyl semimetal, Mn2.94Ge (Ge-rich).

We report on the magnetic and Hall effect measurements of the magnetic Weyl semimetal, Mn2.94Ge (Ge-rich) single crystal. From the magnetic properties study, we identify unusual multiple magnetic transitions below the Ne'el temperature of 353 K, such as the spin-reorientation (TSR) and ferromagnetic-like transitions. Consistent with the magnetic properties, the Hall effect study shows unusual behavior around the spin-reorientation transition. Specifically, the anomalous Hall conductivity increases with increasing temperature, reaching a maximum atTSR, which then gradually decreases with increasing temperature. This observation is quite in contrast to the Mn3+δGe (Mn-rich) system, though both compositions share the same hexagonal crystal symmetry. This study unravels the sensitivity of magnetic and topological properties on the Mn concentration.

Local-environment-guided selection of atomic structures for the development of machine-learning potentials.

Machine learning potentials (MLPs) have attracted significant attention in computational chemistry and materials science due to their high accuracy and computational efficiency. The proper selection of atomic structures is crucial for developing reliable MLPs. Insufficient or redundant atomic structures can impede the training process and potentially result in a poor quality MLP. Here, we propose a local-environment-guided screening algorithm for efficient dataset selection in MLP development. The algorithm utilizes a local environment bank to store unique local environments of atoms. The dissimilarity between a particular local environment and those stored in the bank is evaluated using the Euclidean distance. A new structure is selected only if its local environment is significantly different from those already present in the bank. Consequently, the bank is then updated with all the new local environments found in the selected structure. To demonstrate the effectiveness of our algorithm, we applied it to select structures for a Ge system and a Pd13H2 particle system. The algorithm reduced the training data size by around 80% for both without compromising the performance of the MLP models. We verified that the results were independent of the selection and ordering of the initial structures. We also compared the performance of our method with the farthest point sampling algorithm, and the results show that our algorithm is superior in both robustness and computational efficiency. Furthermore, the generated local environment bank can be continuously updated and can potentially serve as a growing database of feature local environments, aiding in efficient dataset maintenance for constructing accurate MLPs.

Thermodynamic modelling application for prediction of diffusion formation of supersaturation solution

Abstract In this paper the effect of diffusion formation of supersaturated solid solution in the Al–Ge system is discussed. It was shown that at relatively low temperatures of diffusion annealing, Ge concentration in Al-based solid solution became higher than the solubility limit at given temperatures. The maximal concentration of Ge was determined by extrapolation of the diffusion profile on the Ge/Al interface. Analysis of diffusivity of Al in Ge allowed to suggest that slow diffusion in Ge restricts the formation of Ge-based solid solution. Qualitative approach confirmed this suggestion.

Production Efficiency of Ribbon-Type Sections by the Drawing Method in Doubled-Roll Roller Dies

Introduction. The process of drawing is used to produce a wide range of fashion sections of complex configuration, including thin-walled, ribbon-type, and periodical section profiles.Problem Statement. Because of the complexity of steel ribbon production with flattening machines and high capital intensity of flattening production, since the second half of last century, the manufacturers have been trying to use alternative methods of flattening, in particular drawing in monolithic and double-roll roller dies.Purpose. The purpose of this research is to establish regularities of the influence of different sizing systems and process parameters on the regularities of shape change and energy-force parameters of the drawing process in double-roll roller dies and to determine the most effective schemes for achieving the maximal metal expansion while producing ribbon-type sections.Material and Methods. The materials used are as follows: round billets of 5.9 mm in diameter, made of steel brand St.08А; the methods used are as follows: cool billet processing with varying crimping in the double-roll rol ler die with different gauge systems.Results. The regularities of metal shape change and energy-force parameters alternation of the ribbon-type sec tion drawing process in doubled double-roll roller dies by using different gauge systems have been established. Marginal conditions of the deformation in double-roll dies, which provide stable and smooth drawing process according to the criterion of deformed metal safety factor, have been studied experimentally. The most efficient gau ge system of doubled roller dies, which provides maximal metal expansion while producing ribbon-type sections have been determined experimentally.Conclusions. It has been proposed to use the metal drawing technology in doubled double-roll roller dies with “bullhead-accelerated gauge” system while producing ribbon-type sections with a width-to-thickness ratio of more than 2, for achieving the maximal metal expansion per transition. In addition, such a process is energy efficient as the force of pulling through the roller die decreases.

Cross vendor test‐retest validation of diffusion tensor analysis along the perivascular space (DTI‐ALPS) method for evaluating glymphatic system function in vascular cognitive impairment and dementia (VCID)

AbstractBackgroundGlymphatic system (GS) is a recently discovered brain‐wide perivascular fluid transport system in the cerebral nervous system (CNS)(Benveniste H et al., 2019) The impairment of glymphatic transport has been demonstrated to be associated with several neurological diseases, in particular the vascular cognitive impairment and dementia (VCID)(Tang J et al., 2022). The diffusion tensor analysis along the perivascular space (DTI‐ALPS) was proposed to non‐invasively evaluate the GS clearance dysfunction which has been used to investigate the GS in various pathologies(Taoka T et al., 2017, Hsu JL et al., 2022). However, studies on the cross‐vendor and test‐retest reliability of DTI‐ALPS method are lacking. The current study aimed to perform cross‐vendor, inter‐rater and test‐retest validations of DTI‐ALPS method by using a cohort from the MarkVCID consortium.MethodFifty participants’ DTI data from the MarkVCID consortium (consists of 7 sites) were included in this study: 15 participants were scanned on four MRI scanners; 35 participants underwent two MR scans within 14 days. The DTI data were acquired used a single shell, b = 1000s/mm2, 40‐direction with a voxel size of 2.02.02.0mm3 and six b = 0 s/mm2 on 3T MR scanners from seven sites, including two Siemens systems, one Philips system and one GE system. Two pipelines by using DSI studio and FSL software were developed for data processing and ALPS index calculation (Figure 1). The mean ALPS (mALPS) index was obtained by the average of bilateral ALPS index and was used for testing the inter‐rater, cross‐vendor and test‐retest reliability. The association between mALPS index and Montreal Cognitive assessment (MoCA) scores were evaluated using a general linear model with age and gender as covariate.ResultThe Bland‐Altman plot and scatterplot illustrated the validation results of the mALPS index analyzed using DSI studio and FSL pipelines (Figure 2). The mALPS index demonstrated favorable inter‐scanner reproducibility (ICC = 0.77 to 0.95, P< 0.001), inter‐rater reliability (ICC = 0.96 to 1, P< 0.001) and test‐retest repeatability (ICC = 0.89 to 0.95, P< 0.001). A significantly positive correlation was observed between mALPS index and MoCA scores (r = 0.502, P< 0.01) (Figure 3).ConclusionThe mALPS index offers a robust potential biomarker for evaluating GS clearance function in VCID.

First-Principles Dynamics Investigation of Germanium as an Anode Material in Multivalent-Ion Batteries

Germanium, a promising electrode material for high-capacity lithium ion batteries (LIBs) anodes, attracted much attention because of its large capacity and remarkably fast charge/discharge kinetics. Multivalent-ion batteries are of interest as potential alternatives to LIBs because they have a higher energy density and are less prone to safety hazards. In this study, we probed the potential of amorphous Ge anodes for use in multivalent-ion batteries. Although alloying Al and Zn in Ge anodes is thermodynamically unstable, Mg and Ca alloys with Ge form stable compounds, Mg2.3Ge and Ca2.4Ge that exhibit higher capacities than those obtained by alloying Li, Na, or K with Ge, corresponding to 1697 and 1771 mA·h·g–1, respectively. Despite having a slightly lower capacity than Ca–Ge, Mg–Ge shows an approximately 150% smaller volume expansion ratio (231% vs. 389%) and three orders of magnitude higher ion diffusivity (3.0 × 10−8 vs. 1.1 × 10−11 cm2 s−1) than Ca–Ge. Furthermore, ion diffusion in Mg–Ge occurs at a rate comparable to that of monovalent ions, such as Li+, Na+, and K+. The outstanding performance of the Mg–Ge system may originate from the coordination number of the Ge host atoms and the smaller atomic size of Mg. Therefore, Ge anodes could be applied in multivalent-ion batteries using Mg2+ as the carrier ion because its properties can compete with or surpass monovalent ions. Here, we report that the maximum capacity, volume expansion ratio, and ion diffusivities of the alloying electrode materials can be understood using atomic-scale structural properties, such as the host–host and host–ion coordination numbers, as valuable indicators.

THERMODYNAMIC PROPERTIES OF MELTS OF THE Eu-Ge AND Al-Eu-Ge SYSTEMS

The thermochemical properties of the melts of the Eu–Ge and Al–Eu–Ge systems at 1200–1400 K were determined for the first time by the method of calorimetry. It was established that the minimum value of the enthalpy of mixing of the melts of the Eu–Ge system is -49.1±4.4 for an alloy with xGe = 0.45, ΔH̅∞Eu = -145.7 ± 22.3; ΔH̅∞Ge = −166.8 ± 19.8 kJ/mole at T = 1400 K. The curve of enthalpy of mixing of the studied melts is almost symmetrical, which correlates with the behavior of alloys of this and similar systems in the solid state. The obtained data make it possible to consider the entire spectrum of Ge–Ln systems (lanthanides) and to explain what determines the thermodynamic properties of melts of the Eu–Ge system, in particular, and Ge–Ln, in general. Using the defined thermochemical properties of melts and the known phase diagram of the Eu–Ge system, the Gibbs energy, enthalpy, and entropy of formation of melts, associates in melts, and compounds of the Eu–Ge system were optimized and calculated according to the ideal associated solution (IAS) model. The calculated activities of the components in the melts of this system show large negative deviations from ideal solutions. Using the obtained thermochemical data, the temperatureconcentration dependences of Gibbs energies, enthalpies and entropies of the formation of melts and intermetallics, and the coordinates of the liquidus curve of the state diagram of the Eu–Ge system were also calculated according to the IAS model. The calculated liquidus curve and the one known from experimental data do not fully agree with each other. Comparison of ΔHmin of melts with enthalpies of formation, temperatures of melting Ln5Ge3 compounds, and differences in molar volumes and electronegativities of components of Ge–Ln systems depending on the serial number of Ln showed that they are correlated with each other, and ΔHmin of melts and Ln5Ge3 compounds differ little from each other. In addition, all dependences, with the exception of Δχ, are symbiotic and monotonic, with the exception of compounds and melts of binary Ge–Eu(Yb) systems. It was established that the integral and partial enthalpies of mixing of melts of radial sections with xEu/xGe = 0.85/0.15 and 0.3/0.7 of the Al–Eu–Ge system at 1400 K are exothermic. When aluminum is added to GexEu1-x melts, the thermal effect of its dissolution in the first section initially decreases, and then it increases, and in the second – it increases. This is due to the breaking of strong Eu–Ge bonds and the formation of lower energy bonds between Al and Eu. The thermodynamic properties of melts of the Al–Eu–Ge system were calculated using the “geometric” models and the Redlich-Kister-Mujianu model based on similar data for limiting binary systems. It is shown that those calculated according to the Redlich-Kister-Mujianu model with the ternary contribution L = -220 kJ/mole are in the best agreement with the experimental data. Therefore, the same model was used to calculate other thermodynamic properties of melts of the Al–Eu–Ge system.

Comparing eDQE and eNEQ metrics – is there an alternative approach to assessing image quality in digital mammography?

Abstract Introduction: Early detection of breast cancer requires high-quality mammographic images that have been made possible by the introduction of new technologies, such as full-field digital mammography (FFDM). In this new study, we perform extended measurements to calculate effective detective quantum efficiency (eDQE) and introduce effective noise equivalent quanta (eNEQ). Our aim was to show how these two metrics relate to the image quality of two digital mammography systems. Material and methods: Measurements were performed for a Siemens Mammomat Inspiration and a GE Senographe Pristina system. Each was equipped with an automatic exposure control (AEC) for use in a clinical setting. We used a polymethyl methacrylate (PMMA) phantom at thicknesses of 20, 30, 40 and 70 mm to cover the range of scatter conditions expected in mammography, with and without an anti-scatter grid. The Siemens system had an a-Se detector, and the GE system had an indirect-conversion detector. Measurements of Kerma were performed with Piranha Black 657 meter (RTI Electronics AB). The majority of our calculations were automated, using a modified version of our software. Results: For the two mammographic systems evaluated, we characterized physical quality parameters, such as effective modulation transfer function (eMTF), effective normalized noise power spectrum (eNNPS), eDQE and eNEQ for a wide range of exposures, phantom thicknesses, with and without an anti-scatter grid. Results are presented as a function of spatial frequency. A contrast-detail analysis was performed with a CDMAM 3.4 phantom with dedicated software (CDMAM analysis 1.5.5, NCCPM) and a set of different PMMA phantoms. Conclusions: We successfully demonstrated that the eNEQ metric can be used as a new option to evaluate image quality for images taken with and without a grid and with phantoms of different thicknesses for the Siemens and GE systems. These results were consistent with the results obtained from CDMAM.

Variabilities in apparent diffusion coefficient (ADC) measurements of the spleen and the paraspinal muscle: A single center large cohort study

PurposeEvaluation of the variabilities in apparent diffusion coefficient (ADC) measurements of the spleen (ADCspleen) and the paraspinal muscles (ADCmuscle) to identify the reference organ for normalizing the ADC from the abdominal diffusion weighted imaging (DWI). MethodsTwo MRI scanners, with 314 abdominal exams on the GE and 929 on the Siemens system, were used for MRI examinations including DWI (b-values, 50 and 800 s/mm2). For a subset of 73 exams on the Siemens system a second exam was conducted. Four regions of interest (ROIs) in each exam were placed to measure the ADCspleen and the bilateral ADCmuscle. ADC variability between patients (on each scanner separately), ADC variability due to ROI placement between the two ROIs in each organ, and variability in the subset between the first and second exams were assessed. ResultsThe ADCspleen was more scattered and variable than the ADCmuscle in the comparability (n = 929 and 314 for two MRI scanners, respectively) and repeatability (n = 73) datasets. The Bland-Altmann bias and limits of agreement (LoAs) for the ADCspleen (ICC, 0.47; CV, 0.070) and ADCmuscle (ICC, 0.67; CV, 0.023) in the repeatability datasets (n = 73) were −0.1 (−25.7%–25.6%) and −0.3 (−8.8%–8.1%), respectively. For the Siemens system, the Bland-Altmann bias and LoAs for the ADCspleen (ICC, 0.72; CV, 0.061) and ADCmuscle (ICC, 0.53; CV, 0.030) in the comparability datasets (n = 929) were 2.1 (−20.0%–24.2%) and 0.7 (−10.0%–11.4%), respectively. Similar findings have been found in the GE system (n = 314). The CVs for the ADCmuscle measurements were lower than those of the ADCspleen both in the repeatability and the comparability analyses (all p < 0.001). ConclusionParaspinal muscles demonstrate better reference characteristics than the spleen in estimating ADC variability of abdominal DWI.

Phase equilibria of Zr-Co-Ge ternary system at 1023, 1173 and 1373 K

Phase equilibria of the Zr−Co−Ge ternary system at 1023, 1173 and 1373 K were precisely measured via alloy sampling associated with electron probe microanalysis (EPMA) and X-ray diffraction (XRD) techniques. The isothermal sections in the Zr−Co−Ge system were appropriately constructed, containing 29, 28, and 26 three-phase regions at 1023, 1173, and 1373 K, respectively. Except for confirming the five ternary compounds previously reported in the literature, a new ternary phase τ was detected with a remarkable homogeneity range, consisting of 13.8−19.4 at.% Co at 1023 K, 12.9−19.0 at.% Co at 1173 K and 12.3−14.9 at.% Co at 1373 K. And, an invariant reaction was deduced to occur at a temperature between 1023 and 1173 K, i.e., τ+τ1τ4+ZrGe2. Besides, the third element Ge can partly substitute Co in some Co−Zr intermediate phases, e.g., CoZr2 and Co23Zr6 where the maximum solubility of Ge can separately reach up to 22.8 at.% and 20.3 at.%, respectively.

Brain image quality according to beam collimation width and image reconstruction algorithm: A phantom study

PurposeTo compare quantitatively and qualitatively brain image quality acquired in helical and axial modes on two wide collimation CT systems according to the dose level and algorithm used. MethodsAcquisitions were performed on an image quality and an anthropomorphic phantoms at three dose levels (CTDIvol: 45/35/25 mGy) on two wide collimation CT systems (GE Healthcare and Canon Medical Systems) in axial and helical modes. Raw data were reconstructed using iterative reconstruction (IR) and deep-learning image reconstruction (DLR) algorithms. The noise power spectrum (NPS) was computed on both phantoms and the task-based transfer function (TTF) on the image quality phantom. The subjective quality of images from an anthropomorphic brain phantom was evaluated by two radiologists including overall image quality. ResultsFor the GE system, noise magnitude and noise texture (average NPS spatial frequency) were lower with DLR than with IR. For the Canon system, noise magnitude values were lower with DLR than with IR for similar noise texture but the opposite was true for spatial resolution. For both CT systems, noise magnitude was lower with the axial mode than with the helical mode for similar noise texture and spatial resolution. Radiologists rated the overall quality of all brain images as “satisfactory for clinical use”, whatever the dose level, algorithm or acquisition mode. ConclusionsUsing 16-cm axial acquisition reduces image noise without changing the spatial resolution and image texture compared to helical acquisitions. Axial acquisition can be used in clinical routine for brain CT examinations with an explored length of less than 16 cm.

Interaction of Components and Crystal Structure of Compounds in the Pr–Cu–Ge System

Interaction of Components and Crystal Structure of Compounds in the Pr–Cu–Ge System

KINETICS OF OXIDATION OF Ca–Ge SYSTEM MELTS BY AIR OXYGEN

With the introduction of complex alloys and metals – reoxidizers into liquid steel, their waste is observed, or more precisely, oxidation by the gas phase of the furnace. To select the optimal composition of complex deoxidizers, it is necessary to know the physicochemical laws of this process, which are little studied. To study the kinetics of oxidation of metal melts, the method of continuous sample weighing is used, which is usually used in the study of high-temperature corrosion of solid metals. The mechanism of interaction of liquid metals with oxygen is similar in nature to high-temperature gas corrosion of solid metals. In both cases, adsorption of gas molecules on the metal surface, nucleation, and then growth of an oxide film take place. In this work, the kinetics of oxidation of Ca-Ge melts with atmospheric oxygen was studied using thermogravimetry, IR spectroscopy, and X-ray phase analysis. It is shown that germanium additions up to 33.3 at % increase the resistance of melts to oxidation. An increase in temperature contributes to an increase in the rate of oxidation of melts of the Ca–Ge system. The process of oxidation of the investigated melts obeys the parabolic law. The true rate of oxidation is on the order of 10–4 kg · m–2 · s–1. The apparent activation energy of oxidation, depending on the composition of the alloys, is 39.8–526.7 kJ/mol. The products of melt oxidation are СaGe4О9 and GeО2. The mechanism of the influence of germanium on the kinetics of oxidation of Ca-Ge melts has been established. The CaGe4O9 oxide plays a dominant role in the formation of a protective oxide film.

Spectroscopic study of nitrogen incorporation in Ge, Sb, and Te elemental systems: A step toward the understanding of nitrogen effect in phase-change materials

Nitrogen doping in chalcogenide materials represents a promising way for the improvement of material properties. Indeed, N doping in GeSbTe phase-change alloys have demonstrated to greatly enhance thermal stability of their amorphous phase, necessary to ensure the data retention of the final phase-change memory device. Although it is suggested that the N doping in such alloys leads to the preferential formation of Ge-N bonds, further questions concerning the bonding, in particular, Sb-N and Te-N, and the structural arrangement remain unclear. In this paper, we present a study of as-deposited elemental Ge, Sb, and Te systems and their nitrides (i.e., GeN, SbN, and TeN alloys), using a large range of N content from 0 up to about 50 at. %. The as-deposited alloys are investigated by Fourier transform infrared and Raman spectroscopy. We identify the active vibrational modes associated with the formation of Ge-N, Sb-N, and Te-N bonds, highlighting the impact of N incorporation on the structure of these elemental systems. We further qualitatively compare the GeN, SbN, and TeN experimental spectra with the “ab initio” simulations of the related ideal nitride structures. Finally, the analysis of elemental nitride layers is extended to N-doped GeSbTe alloys, providing deeper understanding of nitrogen bonding in such ternary systems, employed in memory technology.

Analysis and Prediction of the Coupling and Coordinated Development of Green Finance–Environmental Protection in China

Green finance is an important tool to help China accelerate the process of environmental protection, but the level of coupling and coordinated development between it and environmental protection has not yet been explored. This study measures the coupling and coordinated level of the green finance–environmental protection system (GE system) in 30 Chinese provinces from 2011 to 2020 and uses the improved GM (1,1) model based on background value optimization to predict the future development trend of the coupling and coordinated level of the green finance–environmental protection system. The results show that: (1) the national average coupling and coordinated level of the green finance–environmental protection system has been in mild disharmony from 2011 to 2020 all the time, and only Guangdong Province and Zhejiang Province among them have reached the coordination level. (2) The coupling and coordinated level of the green finance–environmental protection system based on regional differences has a large gap, ranking in order: Eastern region &gt; Central region &gt; Western region &gt; Northeast region, where the first-ranked Eastern region leads the rise, while the last-ranked Northeast region even shows a decreasing trend year by year. (3) The national average coupling and coordinated level will reach the coordination level in 2077, which fails to get ahead of the “2060 carbon neutrality” goal. Additionally, from the regional division, the Eastern region will be the first to reach the coordination level (2040), the Central region will reach the coordination level in 2043, the Western region is difficult to reach the coordination level, and the Northeast region shows the deterioration of coupling and coordinated degree, and the regional differences are still obvious. This study aims to reduce regional disparities, improve the coupling and coordinated development level of the green finance–environmental protection system nationwide, and implement the process of green development in China.