RbLn2F7（Ln = Gd, Y, Er, Yb and Lu）, crystallized in the hexagonal RbEr2F7 structure type, is synthesized by a hydrothermal method. The excitation spectra of Eu^3 ＋ -doped RbGd （Y）2F7 suggest that the oxygen conte...RbLn2F7（Ln = Gd, Y, Er, Yb and Lu）, crystallized in the hexagonal RbEr2F7 structure type, is synthesized by a hydrothermal method. The excitation spectra of Eu^3 ＋ -doped RbGd （Y）2F7 suggest that the oxygen content is very low in the samples obtained by hydrothermal synthesis. Only the f-f transitions of Gd^3＋ ions are observed in the excitation spectrum of RbGd2F7：Eu^3＋ （0.5mol%）, while those of Eu^3＋ ions do not appear. When the Gd^3＋ ions are excited, the absorbed energy is transferred efficiently from Gd^3＋ to Eu^3＋ . The spectra show that the doped Eu^3＋ ions are located in non-centrosymmetric sites in hexagonal RbLn2F7.展开更多
Thermodynamic properties for an alloy system play an important role in the materials science and engineer- ing. Therefore, theoretical calculations having the flexibility to deal with complexity are very useful and ha...Thermodynamic properties for an alloy system play an important role in the materials science and engineer- ing. Therefore, theoretical calculations having the flexibility to deal with complexity are very useful and have scien- tific meaning. The Hoch-Arpshofen model was deduced from physical principles and is applicable to binary, ternary and larger system using its binary interaction parameters only. Calculations of the activities of Fe-based liquid alloys are calculated using Hoch-Arpshofen model from data on the binary subsystems. Results for the activities for Fe-Au- Ni, Fe-Cr-Ni, Fe-Co-Cr and Fe-Co-Ni systems at required temperature are presented by Hoch-Arpshofen model. The average relative errors of prediction are 7.8%, 4.5%, 4.9~ and 2.7%, respectively. It shows that the calcu- lated results are in good agreement with the experimental data except Fe-Au-Ni system, which exhibits strong inter- action between unlike atoms. The model provides a simple, reliable and general method for calculating the activities for Fe-based liquid alloys.展开更多
文摘RbLn2F7（Ln = Gd, Y, Er, Yb and Lu）, crystallized in the hexagonal RbEr2F7 structure type, is synthesized by a hydrothermal method. The excitation spectra of Eu^3 ＋ -doped RbGd （Y）2F7 suggest that the oxygen content is very low in the samples obtained by hydrothermal synthesis. Only the f-f transitions of Gd^3＋ ions are observed in the excitation spectrum of RbGd2F7：Eu^3＋ （0.5mol%）, while those of Eu^3＋ ions do not appear. When the Gd^3＋ ions are excited, the absorbed energy is transferred efficiently from Gd^3＋ to Eu^3＋ . The spectra show that the doped Eu^3＋ ions are located in non-centrosymmetric sites in hexagonal RbLn2F7.
基金Sponsored by National Natural Science Foundation of China (51090381)Foundation of Yunnan Educational Committee of China (2010Z013)
文摘Thermodynamic properties for an alloy system play an important role in the materials science and engineer- ing. Therefore, theoretical calculations having the flexibility to deal with complexity are very useful and have scien- tific meaning. The Hoch-Arpshofen model was deduced from physical principles and is applicable to binary, ternary and larger system using its binary interaction parameters only. Calculations of the activities of Fe-based liquid alloys are calculated using Hoch-Arpshofen model from data on the binary subsystems. Results for the activities for Fe-Au- Ni, Fe-Cr-Ni, Fe-Co-Cr and Fe-Co-Ni systems at required temperature are presented by Hoch-Arpshofen model. The average relative errors of prediction are 7.8%, 4.5%, 4.9~ and 2.7%, respectively. It shows that the calcu- lated results are in good agreement with the experimental data except Fe-Au-Ni system, which exhibits strong inter- action between unlike atoms. The model provides a simple, reliable and general method for calculating the activities for Fe-based liquid alloys.
