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A ternary hardening-accelerating admixture for Portland cement, comprising calcium fluoroaluminate (11CaO.7Al2O3.CaF2), calcium thiocyanate (Ca(SCN)2) and triethanolamine (C6H15NO3), was studied. The cement paste was investigated using compressive strength tests, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and porous medium surface area analysis. The results showed that the setting time of the cement had been shortened using the ternary admixture; the fluidity and early strength were improved compared with traditional admixtures cured at ambient temperature (20°C). The compressive strength reached 14·5 MPa at 1 d, which was twice that of cement without admixtures and 0·35 times higher than cement with a sodium chloride (NaCl) triethanolamine admixture. Moreover, the total pore volume in the cement with the ternary admixture was much less than the cement with the sodium chloride–triethanolamine admixture. When the ternary admixture was included, not only was the concentration of calcium ions (Ca2+) in the liquid phase increased, but there was also a complexation reaction between the ternary admixture and clinker, which accelerated the cement hydration reaction, and the concentrations of calcium silicate hydrates and ettringite were increased at an early age. The new admixture is a promising non-chloride accelerator and offers more options in hardening-accelerating admixtures for Portland cement systems.

In this study, the low voltage CHEI program is used to achieve single electron injection in nitride layer of nano-scaled SONOS (polysilicon-oxide-nitride-silicon) devices. By investigating various CHEI conditions and different temperature, the best single electron transfer condition is determined. Under this condition, the single electron induced current steps are in good agreement with theoretical result.

Solar-blind metal-semiconductor-metal (MSM) photodetectors (PDs) with Ni/Au semi-transparent interdigitated contact electrodes are fabricated on Al0.4Ga0.6N epi-layer grown by metal-organic chemical vapor deposition on sapphire substrate. The PD exhibits ultra-low dark current in fA range at room temperature (RT) under 20-V bias and a corresponding breakdown voltage higher than 300 V. The PD also shows a maximum RT quantum efficiency of 64% at ~ 275 nm under 10-V bias with a solar-blind/ultraviolet (UV) rejection ratio up to four orders of magnitude. Even at a high temperature of 150°C, the dark current of the PD is still in fA range with a reasonable rejection ratio of more than 8000, suggesting its potential applications for high-temperature deep-UV detection. The ultra-low dark current achieved is believed to be related to the high-temperature AlN buffer layer used in the epi-structure as well as the coplanar configuration of the MSM PD itself.

To further understand the relationship between the polymer structure and nonlinear optical (NLO) property, in this article, three fluorene-based triazole functional polymers with different linked chains were designed and controllably prepared by click chemistry method. The structures and properties of these polymers were characterized and evaluated with Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, ultraviolet spectroscopy, fluorescence spectra, dynamic state laser light scattering, thermogravimetric analysis, and NLO analyses. The results exhibited that the target polymers displayed good solubility, high thermal stability, and well NLO properties. The relationships between molecular structures and optical properties were investigated by both theoretical simulation and experimental results. It was found that the rigid conjugated linked chain between triazole and chromophore can effectively enhance the NLO properties of the resultant polymers. The suitable rigid and flexible groups in the triazole polymers will result in good thermal stabilities. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40878.

In 0.3Ga 0.7N metal–insulator–semiconductor (MIS) and metal–semiconductor (MS) surface barrier photodetectors have been fabricated. The In0.3Ga0.7N epilayers were grown on sapphire by metalorganic chemical vapour deposition (MOCVD). The photoresponse and reverse current–voltage characteristics of the In0.3Ga0.7N MIS and MS photodetectors were measured. A best zero bias responsivity of 0.18 A/W at 450 nm is obtained for the In0.3Ga0.7N MIS photodetector with 10 nm Si3N4 insulator layer, which is more than ten times higher than the In0.3Ga0.7N MS pho-todetector. The reason is attributed to the decrease of the interface states and increase of surface barrier height by the inserted insulator. The influence of the thickness of the Si3N4 insulator layer on the photoresponsivity of the MIS photodetector is also discussed.

Thirty-pair Al0.3Ga0.7N/AlN distributed Bragg reflectors centred at 320 nm are designed and grown on sapphire substrates by metalorganic chemical vapour deposition. No cracks are observed in the main area of the 2-inch wafer except for about 4 mm margin under an optical microscope. Regular stack of alternating layers is shown by scanning electron microscopy. Clear two-dimensional growth steps and very low surface roughness are shown by atomic force microscopy (AFM). Well-defined periodicity is shown by high resolution x-ray diffraction. High reflectivity of 93% at 313 nm with a bandwidth of 13 nm is obtained.

The unintentionally doped samples of Al0.22Ga0.78N/GaN/Al0.22Ga0.78N/GaN multi-heterostructures have been designed and fabricated. The polarization induced charge and free-carrier charge distributions have been demonstrated and the energy band profile has also been calculated. The results indicate the existence of two-dimensional electron gas (2DEG) and hole well at the heterointerfaces. By means of variable temperature Hall measurements, the carrier mobility and the sheet carrier density were measured from 300 to 77 K. The significant increment of carrier mobility at low temperature also verified the existence of the 2DEG.

The advantages of the p-AlInGaN/GaN superlattices' (SLs) structure as an electron blocking layer (EBL) for InGaN blue light-emitting diodes (LEDs) were studied by experiment and APSYS simulation. Electroluminescence (EL) measurement results show that the LEDs with the p-AlInGaN/GaN SLs' structure EBL exhibited better optical performance compared with the conventional AlGaN EBL due to the enhancement of hole concentration and hole carrier transport efficiency, and the confinement of electrons' overflow between multiple quantum-wells (MQWs) and EBL.

To further investigate the influence of H-bond combining with π–π stack interaction on the optical performances, a few rigid zwitterionic squaraine molecules, with different terminal H-bond recognition abilities, are identified and designed. They can controllably construct a series of supramolecular self-assemblies with different morphologies and dimensions via a simple solution-based self-assembly method under mild conditions. The morphologies, synergetic reinforcing effect, and optical-thermal properties are investigated and confirmed by both theoretical and experimental methods. The results indicate that the morphologies of the resultant self-assemblies can be effectively controlled by rational molecular design, whose absorption and emission spectra and thermal stabilities accordingly change with the alteration of zwitterionic squaraine molecular structures.