Leaching process of germanium oxide dust

A thermodynamic analysis on the acid leaching process of germanium oxide dust and discussion on the behaviors of main substances of the dust in the leaching process were carried out. The effects of temperature, acid concentration, leaching time and stirring speed on the leaching rate of germanium were investigated. Based on the characteristic of the dust, the kinetics and reactive mechanism of acid leaching were studied. The results show that the leaching of the dust by acid belonged to ＂the unreacted core shrinking model＂ of producing solid outgrowth layer. The chemical reaction was controlled by inner diffusion process. The apparent activation energy of leaching process was 12.60 kJ/mol. The leaching reaction of germanium was determined to be mainly second order reaction. The optimum conditions were the reaction temperature of 363 K, the leaching time of 2.5 h, the stirring speed of 120 r/min, the solid-to-liquid ratio of 1/8 and the acid concentration of 120 g/L. Under these conditions, the leaching rate of germanium can come up to more than 87%.

Analyzing the surface passivity effect of germanium oxynitride:a comprehensive approach through first principles simulation and interface state density

High-purity germanium(HPGe)detectors,which are used for direct dark matter detection,have the advantages of a low threshold and excellent energy resolution.The surface passivation of HPGe has become crucial for achieving an extremely low energy threshold.In this study,first-principles simulations,passivation film preparation,and metal oxide semiconductor(MOS)capacitor characterization were combined to study surface passivation.Theoretical calculations of the energy band structure of the -H,-OH,and -NH_(2) passivation groups on the surface of Ge were performed,and the interface state density and potential with five different passivation groups with N/O atomic ratios were accurately analyzed to obtain a stable surface state.Based on the theoretical calculation results,the surface passivation layers of the Ge_(2)ON_(2) film were prepared via magnetron sputtering in accordance with the optimum atomic ratio structure.The microstructure,C-V,and I-V electrical properties of the layers,and the passivation effect of the Al/Ge_(2)ON_(2)/Ge MOS were characterized to test the interface state density.The mean interface state density obtained by the Terman method was 8.4×10^(11) cm^(-2) eV^(-1).The processing of germanium oxynitrogen passivation films is expected to be used in direct dark matter detection of the HPGe detector surface passivation technology to reduce the detector leakage currents.

Facile synthesis of porous germanium-iron bimetal oxide nanowires as anode materials for lithium-ion batteries

Germanium-based oxide has been found to be a promising high-capacity anode material for lithium-ion batteries （LIBs）. However, it exhibits poor electrochemical performance because of the drastic volume change during cycling. Herein, we designed porous Ge-Fe bimetal oxide nanowires （Ge-Fe-Ox-700 NWs） by a large-scale and facile solvothermal reaction. When used as the anode material for LIBs, these Ge-Fe-Ox-700 NWs exhibited superior electrochemical performance （- 1,120 mAh·g^-1 at a current density of 100 mA·g^-1） and good cycling performance （- 750 mAh·g^-1 after 50 cycles at a current density of 100 mA·g^-1）. The improved performance is due to the small NW diameter, which allows for better accommodation of the drastic volume changes and zero-dimensional nanoparticles, which shorten the diffusion length of ions and electrons.

Ultra-broad near-infrared emission of Bi-doped SiO_2 Al_2O_3 GeO_2 optical fibers

Bi-doped SiO2-Al2O3-GeO2 fiber preforms are prepared by modified chemical vapor deposition （MCVD） and solution doping process. The characteristic spectra of the preforms and fibers are experimentally investigated, and a distinct difference in emission between the two is observed. Under 808-nm excitation, an ultra-broad near-infrared （NIR） emission with full-width at half-maximum （FWHM） of 495 nm is observed in the Bi-doped fiber. This observation, to our knowledge, is the first in this field. The NIR emission consists of two bands, which may be ascribed to the Bi0 and Bi＋ species, respectively. This Bi-doDed fiber is promising for broadband or）tical amolification and widely tunable laser.

Co-,Fe-,Ni-doped and co-doped rutile GeO_(2):insights from ab-initio calculations

Rutile germanium oxide(rutile GeO_(2)),a semiconductor,can act as a half-metallic compound and is a promising material for spintronic and optoelectronic applications.Calculations were performed using the Korringa–Kohn–Rostoker(KKR)approach and the coherent potential approximation(CPA),which were further combined with two approximations,the local density approximation(LDA)and the self-interaction corrected LDA approximation(LDA-SIC),to study the electronic structure of bulk rutile GeO_(2) doped and co-doped with three transition-metal impurities:Fe,Co,and Ni.The doping value was set to 10%,while the co-doping level was set to 5%for each impurity.The main findings of this work are:(1)a direct ultrawide bandgap of4.80 eV is observed and the rutile GeO_(2) exhibits an N-type semiconducting property.(2)Doped and co-doped GeO_(2) acquire a magnetic behavior and exhibit half-metallicity.(3)The mechanism responsible for these properties is also studied.(4)The critical temperature can reach 334 K when GeO_(2) is doped with Fe,while it rises to 398 K when it is co-doped with Fe and Co.(5)The spin polarization can be improved by co-doping.It can be inferred that rutile GeO_(2) doped or codoped with(Co,Fe)transition metals can be considered to be potential candidates for spintronic and optoelectronic applications.