In this paper, Cr-doped LiSrAlF6 crystals are investigated using high-temperature Raman spectroscopy and the single-crystal Raman spectra of Cr：LiSrAlF6 are analysed by factor group theory and comparison with other f...In this paper, Cr-doped LiSrAlF6 crystals are investigated using high-temperature Raman spectroscopy and the single-crystal Raman spectra of Cr：LiSrAlF6 are analysed by factor group theory and comparison with other fluorides. The results indicate that Cr：LiSrAlF6 is stable below its melting point; Raman peaks located at 561,322 and 250 cm-1 are assigned to the Alg modes of AlF6, SrF6 and LiF6 octachdra, respectively; with temperature increasing, Raman peaks associated with AlF6 octahedra shift towards low frequencies, while LiF6 and SrF6 octahedra are temperature- insensitive; around the crystal melting point, three new Raman peaks occur, which are associated with the AlF6 octahedral chain structure. Finally, the microstruetural evolution of Cr：LiSrAlF6 from room temperature to its melting point is discussed based on its Raman spectra.展开更多
The microstructures of Na_(2)Si_(2)O_(5) from room temperature up to 1773 K are studied by high temperature Raman spectroscopy.Deconvolutions of complex Raman spectra of crystal and amorphous states(glass and melt)are...The microstructures of Na_(2)Si_(2)O_(5) from room temperature up to 1773 K are studied by high temperature Raman spectroscopy.Deconvolutions of complex Raman spectra of crystal and amorphous states(glass and melt)are described.The results show that the temperature-dependent Raman spectra clearly indicate phase transition.Relative abundance of various kinds of SiO_(4) tetrahedrons(each Si binding to different number of bridging oxygens)can be qualitatively and quantitatively resolved as to be varied obviously with different temperatures.It manifests that high temperature Raman spectroscopy provides a useful tool for the microstructure research under high temperature and helps to explain the properties of silicate glasses and melts.展开更多
A newly constructed high-temperature Raman spectrometer was used to study the temperature-dependence Raman spectra(up to 2023 K)and transformation of zirconia crystal.High-temperature Raman scattering is a useful tool...A newly constructed high-temperature Raman spectrometer was used to study the temperature-dependence Raman spectra(up to 2023 K)and transformation of zirconia crystal.High-temperature Raman scattering is a useful tool in characterizing the different structures of zirconia and offers the possibility to identify the phase transformation.It shows that monoclinic zirconia transforms to tetragonal phase at about 1440 K during the process of increasing temperature,but shows a lower transformation temperature from tetragonal to monoclinic phase at about 1323 K while the temperature decreased.展开更多
基金Project supported by the Key Program of the National Natural Science Foundation of China （Grant No. 50932005） and the Open Poject of Shanghai Key Laboratory of Modern Metallurgy and Materials Processing （Grant No. SELF-2009-01）.
文摘In this paper, Cr-doped LiSrAlF6 crystals are investigated using high-temperature Raman spectroscopy and the single-crystal Raman spectra of Cr：LiSrAlF6 are analysed by factor group theory and comparison with other fluorides. The results indicate that Cr：LiSrAlF6 is stable below its melting point; Raman peaks located at 561,322 and 250 cm-1 are assigned to the Alg modes of AlF6, SrF6 and LiF6 octachdra, respectively; with temperature increasing, Raman peaks associated with AlF6 octahedra shift towards low frequencies, while LiF6 and SrF6 octahedra are temperature- insensitive; around the crystal melting point, three new Raman peaks occur, which are associated with the AlF6 octahedral chain structure. Finally, the microstruetural evolution of Cr：LiSrAlF6 from room temperature to its melting point is discussed based on its Raman spectra.
基金Supported by the National Natural Sciences Foundation of China under Grant Nos.59874016 and 59832080the Shanghai Research Center for Advanced Materials under Grant No.98JC14018Shanghai Educational Council.
文摘The microstructures of Na_(2)Si_(2)O_(5) from room temperature up to 1773 K are studied by high temperature Raman spectroscopy.Deconvolutions of complex Raman spectra of crystal and amorphous states(glass and melt)are described.The results show that the temperature-dependent Raman spectra clearly indicate phase transition.Relative abundance of various kinds of SiO_(4) tetrahedrons(each Si binding to different number of bridging oxygens)can be qualitatively and quantitatively resolved as to be varied obviously with different temperatures.It manifests that high temperature Raman spectroscopy provides a useful tool for the microstructure research under high temperature and helps to explain the properties of silicate glasses and melts.
基金Supported by the National Natural Sciences Foundation of China under grant Nos.59874016 and 59832080the Shanghai Research Center for Advanced Materials under grant No.98JC14018 and Shanghai Educational Council.
文摘A newly constructed high-temperature Raman spectrometer was used to study the temperature-dependence Raman spectra(up to 2023 K)and transformation of zirconia crystal.High-temperature Raman scattering is a useful tool in characterizing the different structures of zirconia and offers the possibility to identify the phase transformation.It shows that monoclinic zirconia transforms to tetragonal phase at about 1440 K during the process of increasing temperature,but shows a lower transformation temperature from tetragonal to monoclinic phase at about 1323 K while the temperature decreased.
