PbSe films were grown on(111)-oriented BaF_(2)substrates by using molecular beam epitaxy.High resolution x-ray diffraction characterization showed good crystalline quality of PbSe films.Both longitudinal optical phono...PbSe films were grown on(111)-oriented BaF_(2)substrates by using molecular beam epitaxy.High resolution x-ray diffraction characterization showed good crystalline quality of PbSe films.Both longitudinal optical phonon at 135cm^(-1)and transverse optical phonon at 47.6cm-1 were observed by Raman scattering measurements.The Raman tensor calculation demonstrates that both transverse-optical and longitudinal-optical(LO)phonons in PbSe crystal are Raman active on(111)-oriented surface,Furthermore,2LO phonon at about 270cm^(-1)and polaron at about 800cm^(-1)in PbSe,were also observed.The observed Raman frequencies are in good agreement with theoretical calculations using point ion model.展开更多
Nanolaminated Ti3AlC2honeycomb monolith with parallel and uniform holes has been prepared through a facile extrusion route by using Ti3AlC2powder as the main raw material.The fabricated honeycomb monolith has high com...Nanolaminated Ti3AlC2honeycomb monolith with parallel and uniform holes has been prepared through a facile extrusion route by using Ti3AlC2powder as the main raw material.The fabricated honeycomb monolith has high compressive strength of 133 ± 11 and 59 ± 9 MPa,along and perpendicular to the extrusion direction,respectively.It also has good electrical conductivity,and excellent match of thermal expansion coefficient with the washcoat material of γ-AI2O3.These combined properties endow the honeycomb monolith a promising candidate as catalysis substrate for cleaning vehicle exhaust.展开更多
基金Supported in part by the National Natural Science Foundation of China under Grant No.69606006Oklahoma Center for the Advancement of Science and Technology(OCAST#AR6-054).
文摘PbSe films were grown on(111)-oriented BaF_(2)substrates by using molecular beam epitaxy.High resolution x-ray diffraction characterization showed good crystalline quality of PbSe films.Both longitudinal optical phonon at 135cm^(-1)and transverse optical phonon at 47.6cm-1 were observed by Raman scattering measurements.The Raman tensor calculation demonstrates that both transverse-optical and longitudinal-optical(LO)phonons in PbSe crystal are Raman active on(111)-oriented surface,Furthermore,2LO phonon at about 270cm^(-1)and polaron at about 800cm^(-1)in PbSe,were also observed.The observed Raman frequencies are in good agreement with theoretical calculations using point ion model.
基金supported by the National Natural Science Foundation of China(Nos.50802097 and 50832008)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministrythe support of K.C.Wang Education Foundation, Hong Kong
文摘Nanolaminated Ti3AlC2honeycomb monolith with parallel and uniform holes has been prepared through a facile extrusion route by using Ti3AlC2powder as the main raw material.The fabricated honeycomb monolith has high compressive strength of 133 ± 11 and 59 ± 9 MPa,along and perpendicular to the extrusion direction,respectively.It also has good electrical conductivity,and excellent match of thermal expansion coefficient with the washcoat material of γ-AI2O3.These combined properties endow the honeycomb monolith a promising candidate as catalysis substrate for cleaning vehicle exhaust.
