Roman scattering measurement of （ 1 - x ） GeS2-x Ga2S3 system glasses was conducted in order to understand the microstructural change caused by the addition of Ga2S3 . According to the change of Raman spectra with t...Roman scattering measurement of （ 1 - x ） GeS2-x Ga2S3 system glasses was conducted in order to understand the microstructural change caused by the addition of Ga2S3 . According to the change of Raman spectra with the addition of Ga2S3, two main structural transformations were deduced ： the gradual enhancement of ethane- like structural units S3 Ge- GeS3 （ 250 cm ^- 1） and S3 Ga- GaS3 （270 cm ^- 1 ） and the appearance of charge imbalanced units [ Ga2 S2 （ S1/2 ）4 ]^2- and [Ga（ S1/2 ）4 ]^- . And this change of structural aspect seems to give as a clue to understanding the cause of the increased rare-earth solubility.展开更多
The oxidation behaviors of bulk Ti3Si(1-x)AlxC2 prepared by hot pressing were investigated. The results show that the isothermal oxidation behavior of Ti3SiC2 obeys a parabolic law between 900 and 1 100℃and follows a...The oxidation behaviors of bulk Ti3Si(1-x)AlxC2 prepared by hot pressing were investigated. The results show that the isothermal oxidation behavior of Ti3SiC2 obeys a parabolic law between 900 and 1 100℃and follows a two-step parabolic rate law between 1 200℃and 1 300℃. The cyclic oxidation behavior of material is assumed to obey a three-step parabolic rate law at 1 100℃and 1 200℃. The calculated activation energy of isothermal oxidation is 101.43 kJ/mol. The oxide layers which consist of a mass ofα-Al2O3 and little TiO2 and SiO2 are observed on Ti3SiC2 as a dense and adhesive protect scale. The oxidation mechanism varies with the additive aluminum that greatly improves the oxidation resistance of Ti3SiC2.展开更多
文摘Roman scattering measurement of （ 1 - x ） GeS2-x Ga2S3 system glasses was conducted in order to understand the microstructural change caused by the addition of Ga2S3 . According to the change of Raman spectra with the addition of Ga2S3, two main structural transformations were deduced ： the gradual enhancement of ethane- like structural units S3 Ge- GeS3 （ 250 cm ^- 1） and S3 Ga- GaS3 （270 cm ^- 1 ） and the appearance of charge imbalanced units [ Ga2 S2 （ S1/2 ）4 ]^2- and [Ga（ S1/2 ）4 ]^- . And this change of structural aspect seems to give as a clue to understanding the cause of the increased rare-earth solubility.
基金Project (KF200505) supported by the Key Laboratory of Heavy Ion Physics (Peking University), Ministry of Education
文摘The oxidation behaviors of bulk Ti3Si(1-x)AlxC2 prepared by hot pressing were investigated. The results show that the isothermal oxidation behavior of Ti3SiC2 obeys a parabolic law between 900 and 1 100℃and follows a two-step parabolic rate law between 1 200℃and 1 300℃. The cyclic oxidation behavior of material is assumed to obey a three-step parabolic rate law at 1 100℃and 1 200℃. The calculated activation energy of isothermal oxidation is 101.43 kJ/mol. The oxide layers which consist of a mass ofα-Al2O3 and little TiO2 and SiO2 are observed on Ti3SiC2 as a dense and adhesive protect scale. The oxidation mechanism varies with the additive aluminum that greatly improves the oxidation resistance of Ti3SiC2.
