Different C_(60) crystals were synthesized by precipitation from a mixture of the good solvent m-xylene and the poor solvent isopropyl alcohol.The samples were characterized by scanning electron microscopy(SEM),Raman ...Different C_(60) crystals were synthesized by precipitation from a mixture of the good solvent m-xylene and the poor solvent isopropyl alcohol.The samples were characterized by scanning electron microscopy(SEM),Raman spectroscopy,thermogravimetric analysis,and high resolution transmission electron microscope(HRTEM).We found that the morphologies and sizes of the samples could be controlled by adjusting the volume ratio between the good and poor solvents.Especially,an unexpected short flower column-like crystal was synthesized at low ratios(from 1:6 to 1:12).Room temperature photoluminescence(PL)and HRTEM studies of the C_(60) crystal samples reveal that the PL efficiency of the crystals decreases with increasing crystalline order and that the disordered C_(60) crystals synthesized at the ratio of 1:2 show 10 times higher PL efficiency than that of pristine C_(60).The mechanism of the growth process of these C_(60) crystals was also studied by replacing the good solvents m-xylene with toluene and mesitylene.展开更多
C_(60) and C_(70) single crystals free from solvent contamination grew from their vapour. Large C_(60) crystals up to a size of about 5 mm × 3 mm × 3 mm and C_(70) crystals about 1 mm × 1 mm × ...C_(60) and C_(70) single crystals free from solvent contamination grew from their vapour. Large C_(60) crystals up to a size of about 5 mm × 3 mm × 3 mm and C_(70) crystals about 1 mm × 1 mm × 1 mm were obtained. C_(60) crystals with fee structure showed two types of morphological faces, namely {111} and {100 },frequently with twinning on {111} face. C_(70) crystals obtained have a hop structure with a = 10. 1 andc=16. 7 DSC and X-ray diffraction analysis indicated that C(70) crystal underwent phase transition below 100 ℃ Morphological observation suggests that the growth of C(60) and C(70) single crystals is based on layer spreading mechanism.展开更多
The solubilities of C60 and C70 in toluene, o-xylene and CS2 between melting point and boiling point have been measured. The temperature-dependent solubillty of C60 displays the anomalous behavior. A solubility maximu...The solubilities of C60 and C70 in toluene, o-xylene and CS2 between melting point and boiling point have been measured. The temperature-dependent solubillty of C60 displays the anomalous behavior. A solubility maximum of C60 around O℃ for toluene and CS2, and around 30℃ for o-xylene was observed. The temperature-dependent solu bility of C70 displays the normal behavior in the same solvents.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504269 and 11504267)Tianjin Natural Science Foundation(Grant No.20JCQNJC00660)the Program for Innovative Research in University of Tianjin(Grant No.TD13-5077).
文摘Different C_(60) crystals were synthesized by precipitation from a mixture of the good solvent m-xylene and the poor solvent isopropyl alcohol.The samples were characterized by scanning electron microscopy(SEM),Raman spectroscopy,thermogravimetric analysis,and high resolution transmission electron microscope(HRTEM).We found that the morphologies and sizes of the samples could be controlled by adjusting the volume ratio between the good and poor solvents.Especially,an unexpected short flower column-like crystal was synthesized at low ratios(from 1:6 to 1:12).Room temperature photoluminescence(PL)and HRTEM studies of the C_(60) crystal samples reveal that the PL efficiency of the crystals decreases with increasing crystalline order and that the disordered C_(60) crystals synthesized at the ratio of 1:2 show 10 times higher PL efficiency than that of pristine C_(60).The mechanism of the growth process of these C_(60) crystals was also studied by replacing the good solvents m-xylene with toluene and mesitylene.
文摘C_(60) and C_(70) single crystals free from solvent contamination grew from their vapour. Large C_(60) crystals up to a size of about 5 mm × 3 mm × 3 mm and C_(70) crystals about 1 mm × 1 mm × 1 mm were obtained. C_(60) crystals with fee structure showed two types of morphological faces, namely {111} and {100 },frequently with twinning on {111} face. C_(70) crystals obtained have a hop structure with a = 10. 1 andc=16. 7 DSC and X-ray diffraction analysis indicated that C(70) crystal underwent phase transition below 100 ℃ Morphological observation suggests that the growth of C(60) and C(70) single crystals is based on layer spreading mechanism.
文摘The solubilities of C60 and C70 in toluene, o-xylene and CS2 between melting point and boiling point have been measured. The temperature-dependent solubillty of C60 displays the anomalous behavior. A solubility maximum of C60 around O℃ for toluene and CS2, and around 30℃ for o-xylene was observed. The temperature-dependent solu bility of C70 displays the normal behavior in the same solvents.
