Fabrizio Maseri

Synthesis and characterization of new inorganic polymeric composites based on kaolin or white clay and on ground-granulated blast furnace slag

Alkali activation of dehydroxylated kaolin or clay yielded high-strength polymeric materials, so-called geopolymers. They were synthesized by mixing the aluminosilicate with solutions of sodium metasilicate and KOH followed by adding 45 wt.% of ground-granulated blast furnace slag. The influence of the aluminosilicate source, its activation temperature, and the order of mixing raw materials were studied on the workability of the blending paste, the microstructure, and the Vickers hardness of the geopolymer samples. The polymeric material is completely amorphous according to x-ray diffraction. Solid-state 2 7 A1 and 2 9 Si magic-angle-spinning nuclear magnetic resonance showed that the geopolymer consists of AlO 4 and SiO 4 tetrahedra linked together through a polymeric network constituted by branched entities SiQ 4 (4A1) and SiQ 4 (3A1), but also by less-polymerized silicates SiQ 1 and SiQ 2 . Scanning electron microscopy showed a homogeneous polymeric gel matrix containing unreacted slag (and quartz) grains; thermogravimetric analysis and differential scanning calorimetry exhibited a high content of water and an elevated melting point (1260 °C). Vickers hardness values are in the range of 200 MPa.

Laser Desorption/Ionization Fourier Transform Mass Spectrometry of Thin Films Deposited on Silicon by Plasma Polymerization of Acetylene

Thin films deposited on silicon substrate by three different methods of plasma polymerization of acetylene were analyzed by direct laser desorption/ionization Fourier transform mass spectrometry. High-resolution mass spectra showed the presence of carbon clusters and hydrocarbon oligomers in different relative abundances. During unipolar and continuous discharge polymerization of acetylene-hydrogen gas mixtures, quadrupole mass spectra of the plasma constituents showed the presence of molecular species with m/z lower than 100 — mainly peaks of C4H2 and C6H2. Films produced had smooth surfaces and the corresponding LDI-FTMS spectra displayed only carbon cluster signals in the positive ion mode and both hydrocarbon and carbon cluster signals (with much higher relative abundance of carbon cluster signals) in the negative ion mode. Alternatively, during bipolar discharge with either higher acetylene gas flux (>40 cm3/min) or longer deposition times (>10 min), quadrupole mass spectra of the plasma constituents showed signals corresponding to polycyclic aromatic hydrocarbons (PAH) with m/z higher than 100. SEM pictures of the bipolar thin films demonstrated the presence of “flower” structures and nanoparticles developed on the surface. LDI-FTMS spectra of such thin films showed either total absence or lower relative abundance of carbon cluster signals, compared with hydrocarbon signals.

Large white organic light-emitting diode lighting panel on metal foils

Large-area top-emitting PIN structure (highly p- and n- type doped transport layers for electrons and holes and an undoped emitter layer)-organic light-emitting diode (OLED) on advanced metal foils were fabricated for lighting applications. ArcelorMittal has developed a new surface treatment on metal foils, suitable for roll-to-roll production and dedicated to large-area device integration. Both monochromatic and white devices are realized on advanced metal foils. Power efficiencies at 1000 cd/m 2 of >70 lm/W (green), moreover, power efficiency of white devices of >22 lm/W are achieved. Furthermore, first large-area 60 × 60 cm white OLED sources on metal foils are presented. C 2011 Society of Photo-Optical Instrumentation Engineers

Novel high thermal barrier layers for flexible CIGS solar cells on stainless steel substrates

For the fabrication of monolithically integrated flexible CIGS modules on stainless steel, individual photovoltaic cells must be insulated from the metal substrates by a barrier layer that can sustain high temperature treatment. In this work combination of sol-gel (organosilane-sol) and sputtered SiAlxOy thin layers (TDBL) were prepared on stainless steel substrates. At first, the deposition of organosilane-sol dielectric layers on the commercial AISI-316–2RB stainless steel (Rz = 500 nm, RMS= 56 nm) induces a planarization of the surfaces (RMS = 16.4nm, Rz =176nm). The leakage current in DC mode through the dielectric layers was measured by preparing metal-insulator-metal (MIM) junction that acts as capacitor. This method proposed here allowed us to quantify the quality the quality of our TDBL insulating layer and its lateral uniformity. Indeed, evaluating a ratio of the number of valid MIM capacitors to the number of tested MIM capacitors, a yield of ∼ 95% and 50% has been reached respectively with non annealed and annealed samples based sol-gel double layer. A yield of 100% has been reached with reinforced PCDP by sputtered SiAlxOy thin layer showing perfect electrical insulation. Since this yield is obtained on several samples, it can be extrapolated to any substrate size. Furthermore, according to Glow Discharge Optical Emission Spectroscopy (GDOES) measurements, these barrier layers exhibit excellent barrier properties against the diffusion of undesired atoms which could spoil the electronic and optical properties of CIGS based photovoltaic cells.