Near-normal incident infrared reflectivity spectra of （100） MgAl2O4 spinel single crystal have been measured at different temperatures in the frequency region between 50 and 6000 cm^-1. Eight infrared-active phonon ...Near-normal incident infrared reflectivity spectra of （100） MgAl2O4 spinel single crystal have been measured at different temperatures in the frequency region between 50 and 6000 cm^-1. Eight infrared-active phonon modes are identified, which are fitted with the factorized form of the dielectric function. The dielectric property and optical conductivity of the MgAl2O4 crystal are analysed. From TO/LO splitting, the effective Szigeti charges and Born effective charges at different temperatures are calculated for studying the ionicity and the effect of polarization. Based on the relationship between the （LO-TO）1 splitting, which represents the transverse and longitudinal frequencies splitting of the highest energy phonon band in the reflectivity spectrum, and the ionic-covalent parameter, the four main phonon modes are assigned. MgA1204 can be considered as a pure ionic crystal and its optical characters do not change with decreasing temperature, so it may be used as a suitable substrate for high-Tc superconducting thin films.展开更多
The corrosion resistance behavior of a highly dispersed MgO-MgAl2O4-ZrO2 composite refractory material is examined by testing with high-basicity and low-basicity RH(Ruhrstahl-Hereaeus)slags.The composite material exhi...The corrosion resistance behavior of a highly dispersed MgO-MgAl2O4-ZrO2 composite refractory material is examined by testing with high-basicity and low-basicity RH(Ruhrstahl-Hereaeus)slags.The composite material exhibits greater resistance to the RH slags than the traditional MgO-Cr2O3 composite,MgO-ZrO2 composite,and MgO-MgAl2O4-ZrO2 composite.On the basis of the microstructural analysis and mechanisms calculations,the corrosion resistance behavior of the MgO-MgAl2O4-ZrO2 composite is attributable to its highly dispersed structure,which helps protect the high activity of ZrO2.When in contact with the slag,ZrO2 reacts with CaO to form the stable phase CaZrO3,which protects MgAl2O4 against corrosion,thereby enhancing the corrosion resistance of the composite.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 10474128） and Chinese Academy of Sciences.
文摘Near-normal incident infrared reflectivity spectra of （100） MgAl2O4 spinel single crystal have been measured at different temperatures in the frequency region between 50 and 6000 cm^-1. Eight infrared-active phonon modes are identified, which are fitted with the factorized form of the dielectric function. The dielectric property and optical conductivity of the MgAl2O4 crystal are analysed. From TO/LO splitting, the effective Szigeti charges and Born effective charges at different temperatures are calculated for studying the ionicity and the effect of polarization. Based on the relationship between the （LO-TO）1 splitting, which represents the transverse and longitudinal frequencies splitting of the highest energy phonon band in the reflectivity spectrum, and the ionic-covalent parameter, the four main phonon modes are assigned. MgA1204 can be considered as a pure ionic crystal and its optical characters do not change with decreasing temperature, so it may be used as a suitable substrate for high-Tc superconducting thin films.
基金financially supported by the National Natural Science Foundation of China (No.51872023)
文摘The corrosion resistance behavior of a highly dispersed MgO-MgAl2O4-ZrO2 composite refractory material is examined by testing with high-basicity and low-basicity RH(Ruhrstahl-Hereaeus)slags.The composite material exhibits greater resistance to the RH slags than the traditional MgO-Cr2O3 composite,MgO-ZrO2 composite,and MgO-MgAl2O4-ZrO2 composite.On the basis of the microstructural analysis and mechanisms calculations,the corrosion resistance behavior of the MgO-MgAl2O4-ZrO2 composite is attributable to its highly dispersed structure,which helps protect the high activity of ZrO2.When in contact with the slag,ZrO2 reacts with CaO to form the stable phase CaZrO3,which protects MgAl2O4 against corrosion,thereby enhancing the corrosion resistance of the composite.
