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Ab initio study of the electronic properties of Mg 1-x Bi X O alloys Ph.D. (c) Patricia Abdel Rahim Bogotá, Colombia

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Ab initio study of the electronic properties of Mg1-xBiXO alloys

Ph.D. (c) Patricia Abdel RahimBogotá, Colombia

Universidad de Tokio

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Índice

• Introducción • Motivación• Nuestro trabajo

CsCl NaCl NiAs

WZZnS

Ab initio study of the electronic properties of Mg1-xBiXO alloys

Using the method in first-principles, we have investigated the electronic properties of the compound Mg1-xBixO with varying concentrations of 0%, 25%, 50% and 75% x of bismuth in the phases in sodium chloride (NaCl), cesium chloride (CsCl), zinc-blende (ZnB), wurtzite (WZ) and nickel arsenidine (NiAs) (including spin).

We calculated the band structure and the density of states in the equilibrium volume of the structures for the different phases. The calculations were performed using the first-principles pseudo-potential method in the framework of the spin Density Functional Theory (DFT). The exchange and correlation effects are treated by using the Generalized Gradient Approximation (GGA) as it is implemented in the Perdew - Burke- Ernzerhof- method (PBE). The calculations were performed using the pwscf code, distributed with the Quantum-ESPRESSO package.

Structural parameters of Mg1-xBiXO alloys

Structural parameters of Mg1-xBiXO alloys

Transiciones de fase para esta estructura

Electronic properties of Mg1-xBiXO alloys in the phase NaCl

MgO Mg0.75Bi0.25O Mg0.5Bi0.5O Mg0.25Bi0.75O

Electronic properties of Mg1-xBiXO alloys in the phase NaCl

MgO Mg0.75Bi0.25O

Mg0.5Bi0.5O Mg0.25Bi0.75O

Electronic properties of Mg1-xBiXO alloys in the phase WZ

MgO Mg0.75Bi0.25O Mg0.5Bi0.5O Mg0.25Bi0.75O

Electronic properties of Mg1-xBiXO alloys in the phase WZ

MgO Mg0.75Bi0.25O

Mg0.5Bi0.5O Mg0.25Bi0.75O

Electronic properties of Mg1-xBiXO alloys in the phase ZnS

MgO Mg0.75Bi0.25O

Mg0.5Bi0.5OMg0.25Bi0.75O

Electronic properties of Mg1-xBiXO alloys in the phase ZnS

MgO Mg0.75Bi0.25O Mg0.5Bi0.5O Mg0.25Bi0.75O

Electronic properties of Mg1-xBiXO alloys in the phase CsCl

MgO Mg0.75Bi0.25O

Mg0.5Bi0.5OMg0.25Bi0.75O

Electronic properties of Mg1-xBiXO alloys in the phase CsCl

MgO Mg0.75Bi0.25O Mg0.5Bi0.5O Mg0.25Bi0.75O

Electronic properties of Mg1-xBiXO alloys in the phase NiAs

MgO Mg0.75Bi0.25O

Mg0.5Bi0.5OMg0.25Bi0.75O

Electronic properties of Mg1-xBiXO alloys in the phase NiAs

MgO Mg0.75Bi0.25O Mg0.5Bi0.5O Mg0.25Bi0.75O

Electronic properties of Mg1-xBiXO alloys in the phase Hexa

MgO Mg0.75Bi0.25O

Mg0.5Bi0.5OMg0.25Bi0.75O

Conclusions

Calculations of electronic properties of Mg1-xBixO were carried out by means of DFT using the Wu-Cohen GGA approximation.

It was determined that the MgO has an energy gap the ~ 3 eV and other region down the ~ -1 eV formed mainly by the orbital p the O in the three phases studied and the Mg1-x BixO has a behavior metal for ¼, ½ and ¾ x of Bi in the phases the NaCl, CsCl, NaCl, WZ and ZnS.

ConclusionesCalculations of structural properties of Mg1-xBixO were carried out by means of DFT using the Wu-Cohen GGA approximation. It was determined that at concentrations of 25% there are no phase transitions, while for 100%, 75%, and of 50% x of Bi, if it exists, this can be very useful for future experimental studies of these materials. Furthermore, it was observed that decreasing the lattice constant makes the material become more rigid and hence increases the bulk modulus and the energy. .

Muchas Gracias