Black diamond is obtained by a controlled nanoscale periodic texturing of CVD diamond surface, able to drastically modify the interaction with solar radiation from optical transparency up to solar absorptance values even >90%. Surface texturing, performed by the use of an ultra-short pulse laser, is demonstrated to induce an intermediate band within the diamond bandgap supporting an efficient photoelectronic conversion of sub-bandgap photons (<5.5 eV). The intermediate band introduction results in an external quantum efficiency enhanced up to 800 nm wavelengths (and up two orders of magnitude larger than the starting transparent diamond film), without affecting the film transport capabilities. The optical and photoelectronic outstanding results open the path for future application of black diamond as a photon-enhanced thermionic emission cathode for solar concentrating systems, with advantages of excellent electronic properties combined with a potentially very low work function and high thermal stability

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La 1Àx Sr x Ga 1Ày Mg y O 3À (LSGM) powders containing different amounts of Sr 2+ and Mg 2+ were prepared from precursors synthesised by either Pechini or citrate sol-gel method and by subsequent calcination at 1400 C. Some powders were also submitted to further 10 h firing at 1500 C. All as-calcined powders contained small amounts of Sr-and Ga-containing phases (namely SrLaGa 3 O 7 and SrLaGaO 4 ), as detected by X-Ray Diffraction (XRD). The relative amounts of these phases depended on x and y, i.e. the dopants' levels. Nevertheless, powders prepared by the citrate method exhibited systematically higher phase purity than those obtained by the Pechini process. Calcined powders were then sintered at 1500 C (10 h) in air and the degree of sintering was assessed by scanning electron microscopy (SEM). Phase composition of sintered pellets was different from that of powders. In fact, sintered pellets showed the presence of MgO, as detected by SEM, and of lesser amounts of SrLaGa 3 O 7 . Both these phases were less abundant in materials sintered using powders prepared by citrate method, thus suggesting that Pechini method does not represent the best wet chemical process for manufacturing. The conductivity of sintered pellets was measured by impedance spectroscopy in the 600-800 C interval. Conductivity values of LSGM materials were affected by secondary phase segregation and, therefore, depended on both composition and sol-gel method synthetic route. #

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