Study on solid state reactions of nanocrystalline Cu–Ge alloys upon mechanical alloying and annealing

Abstract

The structural evolution of Cu–12 wt·%Ge (∼Cu–11 at·%Ge) alloy processed by means of mechanical alloying (MA) with subsequent heat treatment was studied using X-ray diffraction profiles, scanning electron microscopy, transmission electron microscopy (TEM) and high resolution TEM observations as well as differential thermal analysis(DTA). The fcc Cu(Ge) solid solution (α) was produced at early stages of MA and amorphised upon further milling. This was followed by the formation of ζ−Cu5Ge intermetallic nanocrystals after 40 h of milling. The subsequent annealing process led to the nanocrystallisation of the amorphous powder. The X-ray crystallite size data showed the exceptional thermal stability of the alloy prepared. The mechanism of the stability was also investigated. In addition, a thermodynamic analysis based on Miedema's semiempirical model was carried out for the evaluation of the experimental results and a good agreement was found between them.

Exceptionally Reversible Li-/Na-Ion Storage and Ultrastable Solid-Electrolyte Interphase in Layered GeP5 Anode

“…Although the peak in the spectrum of the sample that was milled for 2 h is broad and weak, the peak intensity in the spectrum of the sample obtained after 10 h of milling is much higher, while there is no noticeable change in the spectrum of the sample prepared with 50 h of milling. These results clearly show that elemental Ge and RP are initially transformed to an amorphous GeP 5 phase, with further intensive mechanical deformation during high-energy ball milling leading to mechanically driven nanocrystallization that results in the nucleation and growth of a crystalline GeP 5 phase. − As a result, the following phase transition was observed during ball milling of Ge and RP elemental powders (Figure d) …”

“…Figure 1b shows that there is a broad exothermic peak in the range of 180−220 °C for the two samples that were ball-milled for 2 and 10 h, while this was not observed for powders milled for 50 h. This peak could be attributed to the crystallization transition of amorphous GeP 5 in the two samples. 18,19 Given that the powders that had been milled for 2 h were mainly composed of the initial RP and Ge elements, the exothermic crystallization peak in the sample milled for 2 h was negligible. Further confirmation was attained from a comparison of the melting transition in the three samples.…”

“…As shown in Figure 1b, the samples milled for 10 and 50 h exhibited a similar sharp endothermic peak at 500 °C, while the melting temperature of the sample milled for 2 h was completely different. 18,20 The ball-milled powders were also examined by time-of-flight secondary ion mass spectrometry (ToF-SIMS), with results shown in Figure 1c. The spectra of samples that were ball-milled for 2, 10, and 50 h exhibited a GeP − peak located at m/z = 104.88, confirming the formation of a GeP 5 phase.…”

Germaniumbasierte Nanomaterialien für wiederaufladbare Batterien

“…Germanium ist in der Lage, mit vielen verschiedenen Metall‐ und Nichtmetallelementen in variierenden Zusammensetzungen Legierungen zu bilden. Demzufolge haben all diese verschiedenen Legierungen unterschiedliche Eigenschaften und sind als Anodenmaterialien unterschiedlich gut nutzbar . In der Folge stellen wir einige Beispiele vor.…”

Tailoring Ultrafast and High‐Capacity Sodium Storage via Binding‐Energy‐Driven Atomic Scissors

“…In particular, Ge can form alloys of varying compositions with a number of different metal and nonmetal elements. [14,28,29] A typical example includes mixing Si or Al with Ge in silicate lattices during magma crystallization to form a mineral rock with unevenly dispersed Ge. [14] The traditional epitaxial deposition of Ge on the substrate is prone to form a stabilized Ge-based alloy [30][31][32][33][34] and it is difficult to induce further reversible (de) sodiation, complicating the design of the confinement matrix for nanosized Ge dispersions.…”