Effect of gradual ordering of Ge/Sb atoms on chemical bonding: A proposed mechanism for the formation of crystalline Ge2Sb2Te5

Publication date: April 2018 Source:Journal of Solid State Chemistry, Volume 260 Author(s): Janpreet Singh, Gurinder Singh, Aman Kaura, S.K. Tripathi Using first principle calculations, we study the atomic arrangement and bonding mechanism in the crystalline phase of Ge2Sb2Te5 (GST). It is found that the stability of GST depends on the gradual ordering of Ge/Sb atoms. The configurations with different concentration of Ge/Sb in layers have been analyzed by the partial density of state, electron localization function and Bader charge distribution. The s and p-states of Ge atom alter with different stacking configurations but there is no change in Sb and Te atom states. Our findings show that the bonding between Ge-Te is not only responsible for the stability of GST alloy but can also predict which composition can show generic features of phase change material. As the number of Ge atoms near to vacancy layer decreases, Ge donates more charge. A growth model has been proposed for the formation of crystalline phase which justifies the structure models proposed in the literature. Graphical abstract

Source: Journal of Solid State Chemistry - February 4, 2018 Category: Chemistry Source Type: research