Towards understanding the dissolving behaviors of oxygen at finite temperature in Au and Ag: First-principles total energy and phonon spectrum calculations

• Published in: Chinese journal of physics (Taipei) 2017-04, Vol.55 (2), p.218-229
• Main Authors: Zhang, Xu, Wang, Mingli, Yao, Qinglong, Yang, Kun Jie, Hua, Juan, Liu, Yue-Lin
• Format: Article
• Language: English
• Subjects: Au/Ag; First-principles; Oxygen solution; Temperature effect; Vibration spectrum calculations
• ISSN: 0577-9073
• DOI: 10.1016/j.cjph.2017.01.002

•Gold (Au) and silver (Ag) are often used as ideal jewelry materials.•Oxygen (O) is a common impurity significantly affecting the purification.•The O solution behaviors are also fundamental and essential parameters.•The O solution energy depends significantly on the temperature.•First-principles total energy and vibration spectrum calculations have been used. By first-principles total energy and vibration spectrum calculations, we predict the impurity oxygen (O) dissolving behaviors at-finite temperature in Au and Ag. The temperature effect is considered by the lattice expansion and phonon vibration energy. An O atom is invariably preferable to stay at the tetrahedral interstitial site rather than the octahedral interstitial site over the whole temperature regime 200–1200K in two metals. The O solution energy referring to the static O chemical potential μO (T= 0K) decreases with temperature, while the O solution energy in reference to the temperature-dependent O chemical potential μO (T≠0K) increases with the increasing temperature. Meanwhile, phonon vibration energy plays a crucial role in the O dissolving behavior with temperature. Based on the obtained temperature-dependent O solution energy, we predict the O concentration over the temperature range 200–1200K in both metals. Due to that the above data of O dissolving behaviors are rather scarce in both experiment and calculation, our theoretical predictions can provide a very useful reference for purification of Au and Ag as noble metals in industry.