Stable cation inversion at the MgAl2O4(100) surface

From an interplay of atom-resolved noncontact atomic force microscopy, surface x-ray diffraction experiments, and density functional theory calculations, we reveal the detailed atomic-scale structure of the (100) surface of an insulating ternary metal oxide, MgAl2O4 (spinel). We surprisingly find that the MgAl2O4(100) surface is terminated by an Al and O-rich structure with a thermodynamically favored amount of Al atoms interchanged with Mg. This finding implies that so-called Mg-Al antisites, which are defects in the bulk of MgAl2O4, become a thermodynamically stable and integral part of the surface.     

Structure of the Rh2O3(0001) surface

We have studied the (0001) surface termination of Rh₂O₃ on a Rh(111) single crystal using a combination of high resolution core level spectroscopy, low energy electron diffraction, scanning tunneling microscopy and density functional theory. By exposing the Rh(111) to atomic oxygen we are able to grow Rh₂O₃ layers exposing the (0001) surface. The experiments support the theoretical predictions stating that the surface is terminated with an O–Rh–O trilayer yielding a RhO₂ termination instead of a bulk Rh₂O₃ termination. The structural details as found by the DFT calculations are presented and reasons for the previously observed strong differences in catalytic activity between the structurally similar RhO₂ surface oxide, and the Rh₂O₃(0001) surface are discussed.     

Selective growth of individual multiwalled carbon nanotubes

Growth of individual, vertically aligned multiwalled carbon nanotubes (VACNT) on patterned Si wafers using dc plasma-enhanced CVD is described. The selective growth of individual VACNT within larger holes etched in Si is demonstrated for the first time.     

Study of structural and electronic transport properties of Ce-doped LaMnO3

The structural and electronic transport properties of La_1−x Ce _x MnO₃ (x=0.0–1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with Ce doping. They also make a metal-insulator transition (MIT) and transition temperature increases with increase in Ce concentration up to 50% doping. The system La_0.5Ce_0.5MnO₃ also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition.