The Ge-Zn (Germanium-Zinc) system

Investigation on tribological behaviors of biodegradable pure Zn and Zn-X (Li, Cu, Ge) binary alloys

As a potential biodegradable implant material, zinc (Zn) alloys have attracted increasing attention due to their good biocompatibility and moderate degradation rate. Zn and its alloys are expected to become candidate materials for medical devices. The metals implanted in the human body will inevitably undergo friction in the human body before it is completely degraded. Friction and wear are essential factors which may cause medical devices' service failure. However, there are still few studies on the friction and wear properties of biodegradable Zn-based alloys in the human body, and most studies just focus on the mechanical properties, degradation properties and biocompatibility of the alloys. Thus, it is crucial to study the friction and wear properties of Zn and its alloys. In the present work, we investigated the tribological properties of biodegradable pure Zn and Zn-X (Li, Cu, Ge) alloys. Our study found that under simulated body fluid and dry friction conditions, the addition of alloying elements Li and Cu can improve the friction properties of Zn. Among the four metals, Zn-0.5Li alloy has the lowest friction coefficient and the best wear resistance. Hank's solution has lubricating and corrosive effects. That is to say, when the alloy is rubbed in Hank's solution, it can not only be protected by the lubrication of the solution, but also tribocorrosion will occur as well.

Germanium Crystalline Nanomaterials for Li-Ion Storage Prepared by Decomposing LiZnGe in Air

Germanium nanomaterials are important for their potential applications in many fields. However, current synthetic technologies usually involve either high-cost explosive reagents or complicated facilities, which make the mass production especially challenging. In this report, a method was developed to synthesize nano-Ge materials conveniently, realized by decomposing LiZnGe in air at room temperature. The process is nontoxic, inexpensive, and, most of all, very suitable for large-scale production in combination with ball milling. The as-prepared Ge nanomaterials are crystalline whose structures can be flexibly tuned through the ball milling syntheses. As the lithium-ion battery anode, such Ge nanomaterials exhibited long-term cycle ability with high specific capacity as well as excellent rate performance. These results not only provided a very efficient way to prepare nano-Ge in lab or even promising industry production but also suggested a universal method in synthesizing the tetrels elemental nanomaterials.

Microstructure, mechanical properties, biocompatibility, and in vitro corrosion and degradation behavior of a new Zn-5Ge alloy for biodegradable implant materials

Zinc (Zn)-based alloys are considered a new class of biodegradable implant materials due to their superior chemical stability and processability compared to biodegradable magnesium (Mg) alloys. In this study, we report a new biodegradable Zn-5Ge alloy with highly desirable mechanical, corrosion, and biological properties. Microstructural characterization revealed the effective grain-refining effect of germanium (Ge) on the Zn alloy. Tensile test results indicated that the hot-rolled Zn-5Ge alloy showed an ultimate tensile strength of 237.0 MPa, a yield strength of 175.1 MPa, and an elongation of 21.6%; while as-cast pure Zn showed an ultimate tensile strength of 33.6 MPa, a yield strength of 29.3 MPa, and an elongation of 1.2%. The corrosion rates measured by potentiodynamic polarization tests in Hank's solution in ascending order are: as-cast Zn-5Ge (0.1272 mm/y) < as-cast pure Zn (0.1567 mm/y) < hot-rolled Zn-5Ge (0.2255 mm/y) < hot-rolled pure Zn (0.3057 mm/y). Immersion tests revealed that the degradation rate of as-cast Zn-5Ge is 0.042 mm/y, less than half of that of hot-rolled pure Zn and ∼62% of that of as-cast pure Zn. Moreover, the Zn-5Ge alloy showed excellent in vitro hemocompatibility and the addition of 5% Ge effectively enhanced the hemocompatibility of pure Zn. CCK-8 assay using murine preosteoblast MC3T3-E1 cells indicated that the diluted extracts at a concentration <12.5% of both the as-cast Zn-5Ge alloy and pure Zn showed grade 0 cytotoxicity; the diluted extracts at the concentrations of 50% and 25% of Zn-5Ge alloy showed a significantly higher cell viability than those of pure Zn. STATEMENT OF SIGNIFICANCE: Zinc (Zn)-based alloys are currently considered a new class of biodegradable implant materials due to their excellent processability. Here, we report a novel Zn-5Ge alloy with highly desirable mechanical, corrosion and biological properties. The tensile test results indicated that the hot-rolled Zn-5Ge alloy showed an ultimate tensile strength of 237.0 MPa, a yield strength of 175.1 MPa and an elongation of 21.6%; while as-cast pure Zn showed an ultimate tensile strength of 33.6 MPa, a yield strength of 29.3 MPa and an elongation of 1.2%. The corrosion rate measured by potentiodynamic polarization tests in Hank's solution in the ascending order is: as-cast Zn-5Ge (0.1272 mm/y) < as-cast pure Zn (0.1567 mm/y) < hot-rolled Zn-5Ge (0.2255 mm/y) < hot-rolled pure Zn (0.3057 mm/y). Immersion tests revealed that the degradation rate of the as-cast Zn-5Ge is 0.042 mm/y, less than half of that of the hot-rolled pure Zn, ∼62% of that of as-cast pure Zn. Moreover, the Zn-5Ge alloy showed excellent in vitro biocompatibility.