Introduction: Dust formation in mass-loss winds from asymptotic giant branch (AGB) stars is a key process for acceleration of outflows. Equilibrium condensation calculations [e.g., 1] predict that corundum (Al2O3) is one of the first condensates around oxygenrich AGB stars. The presence of presolar corundum grains originated from AGB stars in chondrites [e.g., 25] is also a strong evidence of c...

Ti-doped nano MgAl2O4 for white emission was synthesized by combustion method. Extrinsic Schottky defects, Al vacancies and Ti4+ dopant in Al sites, which are considered to be responsible for bluish-white emission, were observed by STEM on the surface of Ti-doped nano MgAl2O4 powder. The stabilities of the Schottky defect associates, (TiAl·-VAl''')'', were demonstrated by DFT calculation. The e...

The MgAl2O4:Eu2+, Dy3+ nanophosphors with different particle sizes have been synthesized through a simple and inexpensive precipitate approach followed by a post-annealing process. The structure and morphology of the phosphor are characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). According to XRD and TEM results, the particle size of MgAl2O4:Eu2+, Dy3+ could be...

Close lattice matching with a MgAl2O4 (0 0 1) substrate has been used to synthesize thin films of a rare spinel-like polymorph of MgO (b-MgO) that is unstable in bulk form. The film is produced by spin casting an acetate-substituted Mg-ethoxide precursor, which forms a crystalline magnesium acetate phase at room temperature. Pyrolysis of most organic constituents occurs during continuous heatin...

We present opacity sampling model atmospheres, synthetic spectra and colors for brown dwarfs and very low mass stars in two limiting case of dust grain formation: 1) inefficient gravitational settling i.e. the dust is distributed according to the chemical equilibrium predictions, 2) efficient gravitational settling i.e. the dust forms and depletes refractory elements from the gas, but their opa...

Environmental issues regarding Cr6+ formation lead to replacing chrome-containing refractories with greener alternatives. MgO-containing compositions have been extensively investigated for this purpose, however, few studies evaluated the likelihood of using other chemical elements as inducers spinel-like phase in refractory castables. In study, addition zincite alumina-based castables was and c...

Bandgap engineering is central to the design of heterojunction devices. For heterojunctions involving monolayer-thick materials like MoS2, carrier concentration atomically thin film can vary significantly depending on amount charge transfer between MoS2 and substrate. This makes substrates with a range neutrality levels—as case for complex oxide substrates—a powerful addition electrostatic gati...