Degenerately doped metal-oxide nanocrystals (NCs) show localized surface plasmon resonances (LSPRs) that are tunable via their tunable excess charge-carrier densities. Modulation of excess charge carriers has also been used to control magnetism in colloidal doped metal-oxide NCs. The addition of excess delocalized conduction-band (CB) electrons can be achieved through aliovalent doping or by postsynthetic techniques such as electrochemistry or photodoping. Here, we examine the influence of charge-compensating aliovalent dopants on the potentials of excess CB electrons in freestanding colloidal degenerately doped oxide NCs, both experimentally and through modeling. Taking Sn 4+ :In 2 O 3 (ITO) NCs as a model system, we use spectroelectrochemical techniques to examine differences between aliovalent doping and photodoping. We demonstrate that whereas photodoping introduces excess CB electrons by raising the Fermi level relative to the CB edge, aliovalent impurity substitution introduces excess CB electrons by stabilizing the CB edge relative to an externally defined Fermi level. Significant differences are thus observed electrochemically between spectroscopically similar delocalized CB electrons compensated by aliovalent dopants and those compensated by surface cations (e.g., protons) during photodoping. Theoretical modeling illustrates the very different potentials that arise from charge compensation via aliovalent substitution and surface charge compensation. Spectroelectrochemical titrations allow the ITO NC band-edge stabilization as a function of Sn 4+ doping to be quantified. Extremely large capacitances are observed in both In 2 O 3 and ITO NCs, making these NCs attractive for reversible charge-storage applications.

Ag[WI] and A[WI] compounds with A = Na, Li were prepared from binary tungsten iodides (WI) and corresponding metal iodides. Their crystal structures are analyzed on the basis of X-ray diffraction data. Li andNa solid-state NMR measurements reveal that Li and Na ions are distributed over two sites in the respective structures. These results shed some new light on A [MI] with A = alkali and M = Mo, W compounds being reported with x = 1 and 2, which exhibit photophysical properties. The lithium compound is an exception in the series of A[WI] compounds, because it is the only compound which is soluble in water.

No abstract

The mixed anion copper compound Cu(OH)F was studied in measurements of magnetic susceptibility, static and pulsed field magnetization, specific heat, X-band electron magnetic resonance and muon-spin spectroscopy. In variance with its layered structure, the magnetic behavior shows no evidence of low-dimensionality. Cu(OH)F reaches short range static antiferromagnetic order at TN = 9.5  11.5 K and experiences the spin-flop transition at B ~ 3.5 T. This behavior is in a sharp contrast with physical properties of earlier reported isostructural compound Cu(OH)Cl. The first principle calculations reveal highly competitive nature of ferromagnetic and antiferromagnetic superexchange interactions, the details being rather sensitive to choice of magnetic structure employed in the extraction of magnetic interaction. Rather broad anomaly in Cp(T) dependence at phase transition and smeared magnetization curve M(B) at low temperatures suggest static disorder in the ground state. Zero-field μSR data are consistent with Cu(OH)F experiencing a transition into a static magnetically disordered state. 1.Introduction Among numerous building blocks of inorganic chemistry the polyhedral units of divalent copper in oxygen coordination attract most attention in a quest for low dimensional magnetism and superconductivity.1) The copper polyhedra appear to be heavily distorted due to Jahn -Teller effect inherent for electronic 3d 9 shell of Cu 2+ ions. The pseudo-octahedral coordination units CuO6 may differ in their distortion. It could show symmetric or asymmetric shortening and elongation of basal and apical bonds. The positions of the apical ligands may heavily deviate from the normal to the basal plane and the basal plane itself may be bent. In this sense, better description for these units could be given in terms of pyramids CuO5, pseudo-tetrahedral CuO4 units or planar squares CuO4.2) The lower coordination of copper facilitates the reduced dimensionality of magnetic subsystem in the crystal structure. In complex oxides, the copper polyhedra linked through corners, edges or faces frequently form isolated chains or layers separated by nominally non-magnetic structural units. These quasi-onedimensional and quasi-two-dimensional structures develop short-range correlations but may be prevented from reaching a long-range magnetic ordered state. The non-magnetic units providing rather efficient pathways for the exchange interactions help to overcome this difficulty which may result in formation of three-dimensional magnetic order at lowering temperature.3) Similarly the tendency to form low-dimensional magnetic structures is rather pronounced in complex cupric halides and the role of side groups is also important in these compounds.Despite the fact, that both cupric oxide CuO and cupric halides CuX2 (X = F, Cl, Br) have been the topic of research due to their low dimensional magnetic structures, there is renewed interest in these compounds. To some extent, this is due to observation of multiferroicity in these compounds. [4][5][6] In spi...

An unique crystal structure of copper hydroxyl-fluorite, Cu3(OH)2F4, hosts the trimerized chains of both edge-sharing and corner-sharing CuO2F2 plaquettes. The results of the comprehensive study of this compound, including new synthetic route, measurements of specific heat, acand dc-susceptibility, pulsed field magnetization, electron spin resonance, muon spin rotation and relaxation and first principles calculations are presented. The data evidence magnetic phase transition at TC = 12.5 K into canted antiferromagnetic state which is due to antisymmetric Dzyaloshinskii-Moriya (DM) exchange interaction. No alteration of DM component stemming from the intrinsic features of the crystal lattice in Cu3(OH)2F4 results in unusually large spontaneous magnetization. At T < TC, the remanence MR constitutes significant portion of saturation magnetization MS which defines the canting angle  = 4.