| Summary: | The structural, electronic and optical properties of stressed MgO–ZnO nanocomposite alloys with concentrations of Zn and Mg varying from 0.125 to 0.875 were studied using ab initio simulations. Two crystal structures are considered for the initial MgO–ZnO alloys: the rocksalt Mg<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow></mrow><mn>1</mn></msub><msub><mrow></mrow><mo>−</mo></msub><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></mrow></semantics></math></inline-formula>Zn<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></semantics></math></inline-formula>O and wurtzite Zn<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow></mrow><mn>1</mn></msub><msub><mrow></mrow><mo>−</mo></msub><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></mrow></semantics></math></inline-formula>Mg<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></semantics></math></inline-formula>O phases. For rocksalt Mg<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow></mrow><mn>1</mn></msub><msub><mrow></mrow><mo>−</mo></msub><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></mrow></semantics></math></inline-formula>Zn<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></semantics></math></inline-formula>O, the optimized structures are stable at pressures below 10 GPa. The larger the Mg concentration and pressure, the wider the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>E</mi><mi>g</mi></msub></semantics></math></inline-formula> of the rocksalt phase. In contrast, the optimal geometries of wurtzite Zn<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow></mrow><mn>1</mn></msub><msub><mrow></mrow><mo>−</mo></msub><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></mrow></semantics></math></inline-formula>Mg<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></semantics></math></inline-formula>O reveal a diversity of possibilities, including rocksalt, wurtzite and mixed phases. These effects lead to the fact that the optical properties of wurtzite Zn<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow></mrow><mn>1</mn></msub><msub><mrow></mrow><mo>−</mo></msub><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></mrow></semantics></math></inline-formula>Mg<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></semantics></math></inline-formula>O not only demonstrate the properties of the wurtzite phase but also indicate the optical features of the rocksalt phase. In addition, mixed phases of Zn<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow></mrow><mn>1</mn></msub><msub><mrow></mrow><mo>−</mo></msub><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></mrow></semantics></math></inline-formula>Mg<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi mathvariant="normal">x</mi></msub></semantics></math></inline-formula>O simultaneously provide the characteristics of both wurtzite and rocksalt phases with the same structures in different dielectric matrices.
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