Hydration kinetics of cementitious materials composed of red mud and coal gangue

To elucidate the intrinsic reaction mechanism of cementitious materials composed of red mud and coal gangue（RGC）, the hydration kinetics of these cementitious materials at 20°C was investigated on the basis of the Krstulovi？-Dabi？ model. An isothermal calorimeter was used to characterize the hydration heat evolution. The results show that the hydration of RGC is controlled by the processes of nucleation and crystal growth（NG）, interaction at phase boundaries（I）, and diffusion（D） in order, and the pozzolanic reactions of slag and compound-activated red mud-coal gangue are mainly controlled by the I process. Slag accelerates the clinker hydration during NG process, whereas the compound-activated red mud-coal gangue retards the hydration of RGC and the time required for I process increases with increasing dosage of red mud-coal gangue in RGC.

Effect of distortion degree on the hydration of red mud base cementitious material

The interaction of Si anions with Al sites during the hydration process was observed by NMR, IR and SEM to understand the reaction mechanism of the hydrates formation mixed with oil shale calcined at different temperatures. As the reaction progressed, the coordination of Al （Ⅳ, Ⅴ, and Ⅵ） changed almost completely to Ⅳ, when mixed with oil shale calcined at 700 ℃. However, when mixed with oil shale calcined at 400 ℃, some 6-coordination of Al still remained in the hydrates. Under the function of alkaline solutions, which were produced with the hydration of clinker, a certain amount of Si and Al atoms dissolved or hydrolyzed from aluminosilicate, formed geomonomers in solutions, and then polycondensed to form networks.

Synthesis of novel thieno-[3,4-b]-pyrazine-cored molecules as red fluorescent materials

Two novel thieno-[3,4-b]-pyrazine-based molecules, TP-E and TP-O, were designed and synthesized for potential application as red fluorescent emitters. The bulky tetraphenylethylene groups were attached at the periphery of the thieno-[3,4-b]-pyrazine core to form the non-planar molecules, as efficient solid- state emitting materials. The peripheral groups were grafted to the emissive core through either a conjugated acetylene bond, or a non-conjugated ether bond. These molecules exhibit strnng red fluorescence in both dilute solutions and in thin films with large Stokes shifts of over 100 nm. The cyclic voltammetry measurements showed the reversible oxidation and reduction behavior for both compounds. All these properties indicate the two compounds are possible functional materials for use in ontoelectronic devices.

Effect of Oil Shale on Na^+ Solidification of Red Mud-Fly Ash Cementitious Material

Red mud-fly ash based cementitious material mixed with different contents of oil shale calcined at 700 ℃ is investigated in this paper. The effect of active Si and A1 content on the solidification of Na＋ during the hydration process is determined by using X-ray diffraction （XRD）, 27A1 and 29Si magic-angle-spinning nuclear magnetic resonance （MAS-NMR）, infrared （IR）, scanning electronic microscopy （SEM） and X-ray photoelectron spectroscopy （XPS）. It is shown that the content of oil shale has a remarkable effect on the solidified content of Na＋. The hydration process generates a highly reactive intermediate gel phase formed by co-polymerisation of individual alumina and silicate species. This kind of gel is primarily considered as 3D framework of Si04 and A104 tetrahedra interlinked by the shared oxygen atoms randomly. The negative charges and four-coordinated A1 inside the network are mainly charge-balanced by Na＋. The solidifying mechanism of Na＋ is greatly attributed to the forming of this kind of gel.

Oxide ancillary ligand-based europium β-diketonate complexes and their enhanced luminosity

Ternary materials of europium complex with2,2,6,6-tetramethyl-3,5-heptanedione(tmhd) ligand and aqua ligand as ancillary ligands have been prepared and characterized for various optoelectronic characteristics.Reactions of hydrated complex [Eu(tmhd)_(3)(H_(2)O)_(2)] proceeded with triphenylphosphine oxide(TPPO) and pyridine-N-oxide(PNO) ancillary ligands were studied to develop novel complexes. The prepared complexes show good thermal stability. A comparative investigation of preparedmaterials[Eu(tmhd)_(3)(H_(2)O)_(2)],[Eu(tmhd)_(3)(TPPO)_(2)] and [Eu(tmhd)_(3)(PNO)_(2)] was conducted for their luminescent behaviors in order to obtain the role of ancillary ligand in the enhancement of illumination amount generated from europium(Eu^(3+)) ion. Color coordinates of prepared ternary complexes such as[Eu(tmhd)_(3)(H_(2)O)_(2)]with(x = 0.54,y = 0.32),[Eu(tmhd)_(3)(TPPO)_(2)] with(x = 0.56, y = 0.32) and[Eu(tmhd)_(3)(PNO)_(2)] with(x = 0.57, y = 0.33) indicated that these materials exhibited bright red emission in visible region spectrum. The complexes show a proficient energy transport pathway from the ligands to the innermost Eu^(3+)by means of an ancillary ligand-sensitized luminescence process. Interaction between the metal and ligand results in a distinguished effect on quantum efficiency(η) as well as on Judd–Ofelt intensity factor(Ω_(2)) of the prepared materials.