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Field emission properties of vertically aligned gold nanowires of different aspect ratios and spatial distribution are presented. The nanowires were electrochemically deposited into the pores of etched ion-track polymer membranes. High emission site densities up to 5.7×105cm−2 based on a controlled field enhancement β of individual emitting sites were observed by means of field emission scanning microscopy. Local measurements reveal stable Fowler–Nordheim behavior of the emitters up to currents of 100μA. The integral emission of Au nanowires cathodes for device application is also discussed.

The incommensurately modulated crystal structures of Ca(0.28)Ba(0.72)Nb(2)O(6) (CBN28) and Ce(0.02)Ca(0.25)Ba(0.72)Nb(2)O(6) (Ce:CBN28) were refined in the supercentred setting X4bm(AA0,-AA0) of the 3 + 2-dimensional superspace group P4bm(aa½,-aa½). Both compounds are isostructural with a tetragonal tungsten bronze-type structure. The modulation of CBN28 consists of a wavy distribution of Ba and Ca atoms as well as vacancies on the incompletely occupied Me2 site with 15-fold oxygen coordination. The occupational modulation is coupled with a modulation of the atomic displacement parameters and a very weak modulation of the positional parameters of Me2. The surrounding O atoms show strong displacive modulations with amplitudes up to ca 0.2 Å owing to the cooperative tilting of the rigid NbO(6) octahedra. The Me1 site with 12-fold coordination and Nb atoms are hardly affected by the modulations. Only first-order satellites were observed and the modulations are described by first-order harmonics. In Ce:CBN28 cerium appears to be located on both the Me2 and Me1 sites. Wavevectors and structural modulations are only weakly modified upon substitutional incorporation of 0.02 cerium per formula unit of calcium.

One of the goals of crystal engineering is to make it possible to design and synthesize MOFs with predetermined topology and properties, usually through judicious selection of multitopic organic ligands as the spacers and metal ions or clusters as the junctures [1]. As functional metal centers, rare earth metals are attracting more and more attention due to their fantastic coordination properties and special chemical characteristics arising from 4f electrons [2], [3]. Many coordination polymers based on rare earths have been synthesized, and most of them exhibit amazing optical and magnetic properties, enabling them as fluorescent probes and electroluminescence devices [4], [5]. We report herein a family of 11 isostructural 3D metal-organic compounds, {[Ln(µ 3-pmdc)(µ-ox) 0.5 (H 2 O) 2 ]•2.25H 2 O} n

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