Structural relaxation around substitutional Cr3+ in MgAl2O4

Structural relaxation around substitutional Cr3+ in pyrope garnet

The structural environment of substitutional Cr ion in a natural pyrope Mg3Al2Si3O12 has been investigated by Cr K-edge Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) coupled with first-principles computations. The Cr-O distance is close to that in knorringite Mg3Cr2Si3O12, indicating a full relaxation of the first neighbors. The local C3i symm...

X-ray Linear Dichroism in cubic compounds: the case of Cr3+ in MgAl2O4

Yield Strength of Transparent MgAl2O4 Nano-Ceramic at High Pressure and Temperature

We report here experimental results of yield strength and stress relaxation measurements of transparent MgAl2O4 nano-ceramics at high pressure and temperature. During compression at ambient temperature, the differential strain deduced from peak broadening increased significantly with pressure up to 2 GPa, with no clear indication of strain saturation. However, by then, warming the sample above ...

Brightness degradation in electroluminescent ZnS : Cu

Monte Carlo simulations using crystal chemical constraints have been used to elucidate the copper diffusion mechanisms in copper-doped zinc sulfide. Relaxation around the ZnSuCu S interface allows facile copper diffusion, particularly in the 22x presence of substitutional oxygen or sulfur vacancies. Copper diffusion is responsible for the brightness degradation in this electroluminescent materi...

A Comparative DFT Study on Structural and Electronic Properties of C24 and Some of Its Derivatives: C12B6N6, B6N6C12 and B12N12

The structural stabilities, geometry and electronic properties of C24 and some its heterofullerenederivatives are compared at the B3LYP/6-311-EFG**//B3LYP/6-31+G* level of theory. Vibrationalfrequency calculations show that all the systems are true minima. The calculated binding energies ofheterofullerenes show C24 as the, most stable fullerenes by 9.03eV/atom. While decreasing bindingenergy in...