Magnetic and Electronic Properties of Double Perovskite Ba2SmNbO6 without Octahedral Tilting by First Principle Calculations

The structural, magnetic and electronic properties of the double perovskite Ba2SmNbO6 （for the simple cubic structure where no octahedral tilting exists anymore） are studied using the density functional theory within the generalized gradient approximation as well as taking into account the on-site Coulomb repulsive interaction. The total energy, the spin magnetic moment, the band structure and the density of states are calculated. The optimization of the lattice constants is 8.5173 A, which is in good agreement with the experimental value 8.5180 A. The calculations reveal that Ba2SmNbO6 has a stable ferromagnetic ground state and the spin magnetic moment per molecule is 5.00μB/f.u. which comes mostly from the Sin3＋ ion only. By analysis of the band structure, the compound exhibits the direct band gap material and half-metallic ferromagnetic nature with 100% spin-up polarization, which implies potential applications of this new lanthanide compound in magneto-electronic and spintronic devices.

Atomic-scale observation of the deformation and failure of diamonds by in-situ double-tilt mechanical testing transmission electron microscope holder

In-situ transmission electron microscopy(TEM)has been demonstrated to be a powerful method in resolving challenging problems such as interactions among various defects.To take advantage of the atomic resolution of advanced TEMs,a compact five-degree-of-freedom nanomanipulator was integrated with an indenter that was made of nanotwinned diamonds,for both the in-situ mechanical testing and double tilting of TEM samples.As a demonstration,in-situ bending tests were performed on the?111?,?110?and?100?single-crystal diamond needles.The tests revealed the{111}cleavage to be the dominant failure mode.The in-situ indentation on a diamond nanoplate led to curved cracks consisting of nanometer-scale steps,which were identified to be atomic flat{111}facets.The atomic-scale observation of the deformation and failure of diamonds demonstrated the stability of the entire system and the durability of the indenter.We expect that more delicate research can be carried out by means of this holder in the near future,including in-situ stimulation,atomic characterization,and tomography.