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We report results of detailed structural investigations on the system La2-xSrxCuRuO6 (0 <= x <= 1) as a function of composition using neutron powder diffraction. Our results reveal that this series of compounds exhibit an interesting structural transition manifested through Sr doping; with Ru in single valency, in end members, and mixed valency otherwise. The end members La2CuRuO6 and LaSrCuRuO6 crystallize in monoclinic structures with space group P2(1)/n. However, the compositions with intermediate Sr doping (x = 0.2 and 0.8) crystallize in triclinic structure with space group P-1, albeit with minute distortions. The detailed structural studies by neutron powder diffraction at room temperature and at 10 K, for compositions, x = 0.2, 0.8 and 1 are presented. While magnetic measurements are indicative of ferro and antiferromagnetic like transitions for x = 0 and x > 0 respectively, neutron diffraction patterns collected at 10 K and 30 K across the characteristic transition temperature suggested by the magnetic data, do not show any extra peaks or extra intensity at lower temperature as compared to the high temperature, thus, establishing the absence of any long-range magnetic ordering in these samples.

Sn4+-doped In2O3 (ITO) is a benchmark transparent conducting oxide material. We prepared ligand-free but colloidal ITO (8nm, 10% Sn4+) nanocrystals (NCs) by using a post-synthesis surface-modification reaction. (CH3)(3)OBF4 removes the native oleylamine ligand from NC surfaces to give ligand-free, positively charged NCs that form a colloidal dispersion in polar solvents. Both oleylamine-capped and ligand-free ITO NCs exhibit intense absorption peaks, due to localized surface plasmon resonance (LSPR) at around =1950nm. Compared with oleylamine-capped NCs, the electrical resistivity of ligand-free ITO NCs is lower by an order of magnitude (approximate to 35mcm(-1)). Resistivity over a wide range of temperatures can be consistently described as a composite of metallic ITO grains embedded in an insulating matrix by using a simple equivalent circuit, which provides an insight into the conduction mechanism in these systems.

Properties of any heterostructured material depend critically on the specific composition profile of the constituent elements in the sample. X-ray photoelectron spectroscopy (XPS) is particularly well suited to probe elemental composition of any system. Tunable photon energies, available from any synchrotron centre, allow one to map out the compositional variation through a sample in a manner that can be termed non-invasive and non-destructive depth profiling. In addition, XPS is also able to provide depth resolved electronic structure information by directly mapping out occupied states at and near the Fermi energy. Recent developments at various synchrotron centers, providing access up to very high energy (~10 keV) photons with a good resolution and flux, have made it possible to estimate such compositional and electronic structure depth profiles with a greater accuracy for a wider range of materials. In this book chapter, we describe in detail the use of X-ray photoelectron spectroscopy in a selection of heterostructures, in order to illustrate the power of this technique.

We have revisited the valence band electronic structure of NiO by means of hard x-ray photoemission spectroscopy (HAXPES) together with theoretical calculations using both the GW method and the local density approximation + dynamical mean-field theory (LDA+DMFT) approaches. The effective impurity problem in DMFT is solved through the exact diagonalization (ED) method. We show that the LDA+DMFT method in conjunction with the standard fully localized limit (FLL) and around mean field (AMF) double-counting alone cannot explain all the observed structures in the HAXPES spectra. GW corrections are required for the O bands and Ni-s and p derived states to properly position their binding energies. Our results establish that a combination of the GW and DMFT methods is necessary for correctly describing the electronic structure of NiO in a proper ab initio framework. We also demonstrate that the inclusion of photoionization cross section is crucial to interpret the HAXPES spectra of NiO. We argue that our conclusions are general and that the here suggested approach is appropriate for any complex transition metal oxide.