Materials Science Forum Vols. 663-665

Abstract: Uniform 3D flower-like β-In2S3 microstructures were synthesized using InCl3·4H2O and KSCN as starting reagents in ethylene glycol at 200-220°C for 30h under solvothermal conditions. The prepared products were characterized by various techniques, such as XRD, XPS, FESEM, TEM and ED. FESEM and TEM observation reveals that the as-prepared flower-like β-In2S3 microstructures are assembled by plate-like nanocrystals with average thickness of 10nm. These nanoplates interconnect with each other to form an entangled network-like architecture with irregular-shaped pore in the flower-like β-In2S3 microstructures. Photoluminescence (PL) spectrum indicates that the synthesized β-In2S3 porous micro spheres have shown considerably greater quantum size effects.

Abstract: Large-scaled and monodispersed ZnO nanospheres have been synthesized successfully using zinc nitrate hexhydrate and triethanolamine (TEA) aqueous solutions as precursors through a facile one-pot microwave-assisted process in the absence of any template. The as-prepared products were characterized by XRD, EDX, FESEM, TEM, HRTEM and PL. The results reveal that solid ZnO nanospheres possess a hexagonal wurtzite structure with diameters of 240-440 nm, which are self-assembled by single-crystal polygonal nanoflakes with 20-30 nm in side lengths. Room temperature photoluminescence (PL) spectrum shows a strong ultraviolet (UV) emission around 387 nm and a broad green band at the center of 530 nm. The possible formation mechanism was also investigated.

Abstract: This paper proposed a new 2D method to simulate the microstructure for normal grain growth of polycrystalline materials. In this method, the sample was discretized into geometry points and a straightforward geometric construction was implemented to estimate whether the current point was located at the interior of a certain grown grain. The ceramics material was assumed isotropic; furthermore, the single-phase and two-phase systems without pores were discussed respectively. So each grain core would grow up at the same velocity in all directions until it met another growing core in single-phase systems, while in two-phase systems, there would be two sorts of cores with different growing velocities. The ratio of these different velocities was the key factor of the sample microstructures after sintering. The simulation results and the analysis showed that the proposed method agree well with the experimental observation.

Abstract: The reflection and transmission of antiferromagnetic sandwich (SiO2/MnF2/ZnF2), which impacted by third-order nonlinear modification from antiferromagnetic film (MnF2), is analyzed. The obvious effect on the reflection can be observed in the vicinity of the resonant frequency. In order to illustrate the influence of medium on the refection and transmission, the case air/MnF2/air also is considered.

Abstract: Piezoelectric sensor can produce voltage when deflected (function as an energy harvester) while piezoelectric actuator can deflect when a voltage is applied. Different device applications have different requirements on the thickness and in-plane geometry of the Lead Zirconate Titanate(PZT) piezoelectric layers and thus have their own processing difficulties. In this paper, PZT-Au-Si cantilever is fabricated by eutectic bonding and dicing process.The properties of lapped PZT ceramics and silicon cantilever is also evaluated. The PZT-Au-Si cantilever applications for both piezoelectric actuators and energy harvesters have been confirmed.

Abstract: The microstructure and crystallographic characteristics of diamond film deposited with the chemical vapor deposition method was investigated using transmission electron microscopy (TEM). It is found that fivefold twin center does not always behave as growth nuclei of diamond grain. For those behaving as growth nuclei, there are a large amount of defects in every block of fivefold twin. However, for those not behaving as growth nuclei, two blocks of fivefold twin contain large quantities of defects, the other three are nearly clear. High resolution TEM analysis shows stacking faults coexist with microtwins in the two vast-defects-contained blocks. The effect of the mismatch angle (7.5°) in fivefold twins on microtwins, and the coexistence mechanism of both stacking faults and microtwins are also discussed.

Abstract: The thermal expansion of a novel semiconductor material, mercury indium telluride (MIT) grown by vertical Bridgman (VB) method, was measured from room temperature till 573K by two methods, i.e. Macroscopic dilatometric and X-ray measurements. It is found that the macroscopic expansion is quite different from the expansion of the lattice (micro-expansion). The macroscopic expansion is lower than micro-expansion in the temperature range of 303-425.5K and has a minimum of -0.14% linear expansion, while the macro-expansion becomes larger than micro-expansion in the temperature higher than 425.5K. The former may be due to the effects of the existing neutral vacancies. The latter may result from the influence of thermal-activated vacancies on the lattice.

Abstract: A novel tri-functional copolymer P1 containing hole transporting units, electron transporting units and terbium complex units was synthesized via radical copolymerization. It was characterized by DSC, TGA, Fluorescence, CV and I-V data test. The results showed that the copolymer P1 was capable of pure green emission in the solid state under UV excitation and had potential application in the memory or light-emitting device.

Abstract: Poly(methyl methacrylate)(PMMA) and Poly L-lactic acid (PLLA) are transparent and they are suitable for optical purposes. The multi-layer polymer microfabrication can be applied for a large displacement actuator and precision sensors. A new method is intruduced to generate the multi-layer polymers microstructures by X-ray lithography with alignment. The function of X-ray on polymer materials are breaking the polymer main chain and generating intermediates which can be degraded further and finally dissolved by the solvent interaction. The method for polymer micromachining by using X-ray lithography with alignment for fabrication multi-layer micro polymer structures is confirmed experimentatively.

Abstract: The corrosion behavior of lanthanum hexaboride (LaB6) in the environment containing H2S and CO2 was studied. The results show that the corrosion of LaB6 was severe when the environmental temperature and the partial pressure of H2S were high, and the corrosion would preferentially happen at the central part of the sample due to the lower compact of this part.