Atomic resolution imaging and spectroscopy of single Barium atoms and functional groups on graphene oxide

C.B. BOOTHROYD; M.S. MORENO; M. DUCHAMP; A. KOVÁCS; N. MONGE; G.M. MORALES; C.A. BARBERO; R.E. DUNIN-BORKOWSKI

ULTRAMICROSCOPY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 145 p. 66 - 73

0304-3991

We present an atomic resolution transmission electron microscopy (TEM) and scanning TEM (STEM) study of the local structure and composition of graphene oxide modified withBa2+. In our experiments, which arecarried out at 80kV, the acquisition of contamination-free high-resolution STEM images is only possible while heating the sample above 400C using a highly stable heating holder. Ba atoms are identified spectroscopically in electron energy-loss spectrum images taken at 800C and are associated with bright contrast in high-angle annular dark-field STEM images. The spectrum images also show that Ca and O occur together and that Ba is not associated with a significant concentration of O. The electron dose used for spectrum imaging results in beam damage to the specimen, even at elevated temperature. It is also possible to identify Ba atoms in high-resolution TEM images acquired using shorter exposure times at room temperature, thereby allowing the structure of graphene oxide to be studied using complementary TEM and STEM techniques over a wide range of temperatures.