Electrical characterization and examination of temperature-induced degradation of metastable Ge0.81Sn0.19 nanowires

Electrical characterization of Ge0.81Sn0.19 nanowires has been performed revealing high electrical conductivity and semiconductor behaviour when cooled to 10 K. The impact on slightly elevated temperatures on the device stability of this metastable material is described.

Structural Investigations of (GaIn)(NAs)/GaAs Multi-Quantum-Wells by Transmission Electron Microscopy

ABSTRACTThe structure of compressively strained (GaIn)(NAs)/GaAs multi-quantum wells (MQWs) grown by MOVPE is investigated using TEM. The quaternary, metastable material exhibits a high structural perfection if a N concentration of 4% is not exceeded. Phase separation or clustering effects are not observed, and the In is dispersed homogeneously throughout the quantum wells. The interface roughness of the quantum wells to the GaAs barriers is in the order of several monolayers. Increasing the N content to above 4.5% results in a deterioration of the structure and of the homogeneity of the wells

Lattice Dynamical Prediction of the Elastic Constants of Diamond

The thermophysical properties of diamond, a metastable material at room temperature, are difficult to measure at high temperatures. These properties are of interest for testing equation of state and interatomic potential models. Here we utilize a geometrical lattice transformation, one dimensional lattice dynamical theory, and the principle of corresponding states to calculate the elastic constants of diamond over an extended temperature range.

High dielectric SrGeO3 perovskite prepared by high pressure synthesis

ABSTRACTHigh pressure synthesis of SrGeO3 perovskite and its properties are reported. The metastable material recovered to room pressure shows a high dielectric constant (>100), due to a “stretched” crystal lattice.

Nucleation of calcium phosphate from solution

A method of determining the stoichiometry of metastable phases from nucleation characteristics is described and is applied to calcium phosphate precipitation. The stoichiometric ratio [Ca]/[P] is shown to be 1.49 ± 0.02 in the pH range 7.0–9.1, indicating that it is not hydroxyapatite which normally forms first in the physiological pH region. Characterization of the product by radio isotopes and by infrared spectroscopy and electron diffraction confirms the stoichiometry and indicates that the calcium phosphate nucleated from solution at high pH is an amorphous or soft metastable material. Some biological implications of these findings are pointed out.