Search results for "Germanium oxide"
showing 5 items of 5 documents
Defect Luminescence Study in Tetragonal GeO2 Crystals
2000
The perovskite-or rutile-like GeO2 crystals were grown by the “top-seed” method from a fused germanium dioxide solution with sodium bicarbonate. The luminescence was studied under cathode-, x-ray, and photo-excitation. There are two luminescence bands at 550 nm and 400 nm with slow (100–200 µs) and fast (<20 ns) decay, respectively. The luminescence can be excited either by intra-center and electron-hole recombination processes. An analogous luminescence, however with strong non-exponential decay, is observed in glassy materials obtained from the frozen solution. Sodium-germanate glasses melted under oxygen deficient condition also possess similar luminescence, therefore the luminescence is…
Luminescence of polymorph crystalline and glassy SiO2, GeO2: A short review
2009
Studies of SiO 2 and GeO 2 crystals with α-quartz and rutile structures were performed during last two decades. The goal of such studies was comparison of properties with those of glassy modifications of these crystals. Luminescence of oxygen deficient centers in these glassy materials was found to resemble the luminescence of the rutile-type modification rather than α-quartz modification. In α-quartz, similar luminescence centers appear after damaging irradiation by electron beam at low temperatures (<60 K) or at ambient temperatures after gamma or neutron irradiation.
Size dependent light absorption modulation and enhanced carrier transport in germanium quantum dots devices
2015
Quantum confinement in closely packed arrays of Ge quantum dots (QDs) was studied for energy applications. In this work, we report an efficient tuning mechanism of the light harvesting and detection of Ge QDs. Thin films of SiGeO alloys, produced by rf-magnetron sputtering, were annealed at 600 degrees C in N-2 to induce precipitation of small amorphous Ge QDs into the oxide matrix. Varying the Ge content, the QD size was tailored between 2 and 4 nm, as measured by high resolution transmission electron microscopy. X-ray photoelectron spectroscopy (XPS) measurements indicate the formation of pure SiO2, as well as the presence of a sub-stoichiometric Ge oxide shell at the QD interface. Light …
A new method for radiochemical separation of arsenic from irradiated germanium oxide.
2005
Abstract Radioarsenic labelled radiopharmaceuticals could be a valuable asset to Positron Emission Tomography (PET). In particular, the long half-lives of 72 As ( T 1/2 =26 h) and 74 As ( T 1/2 =17.8 d) allow to investigate slow physiological or metabolical processes, like the enrichment and distribution of antibodies in tumor tissue. This work describes the direct production of no-carrier-added (nca) arsenic isotopes *As, with *=71, 72, 73, 74 or 77, the reaction to [*As]AsI 3 and its radiochemical separation from the irradiated solid germanium oxide via polystyrene-based solid-phase extraction. The germanium oxide target, irradiated at a cyclotron or a nuclear reactor, is dissolved in con…
Matrix isolation studies on the co-condensation reactions of molecular SiO and GeO: the characterisation of the novel cyclic species SiGeO(2), Si(2)G…
2010
Matrix isolation IR studies, together with DFT calculations, have established that the co-condensation of molecular SiO and GeO in low temperature (12 K) nitrogen matrices leads to the formation of the novel silicon germanium oxide species SiGeO(2), Si(2)GeO(3) and SiGe(2)O(3) analogous to the known dimer and trimer species M(2)O(2) and M(3)O(3) (M = Si, Ge). Controlled diffusion studies in the temperature range 20-34 K result in a significant increase in trimer formation, which implies a very low activation energy for this oligomerisation step. Characteristic IR modes are assigned for all three novel mixed oxide molecules, and the DFT calculations establish that these species have cyclic C…