Synthesis of zinc and cadmium complexes of 1, 1, 5, 5-tetramethyl-2-4-dithiobiuret (M{N(SCNMe2)2}2) (M = Zn, Cd) is described together with X-ray single crystal of cadmium complex. These complexes have been used as a single molecular precursor for the deposition of ZnS, CdS and ZnxCd1-xS thin films by aerosol assisted chemical vapour deposition (AACVD) method. Adherent specular films of ZnS and CdS were obtained in the temperature range 300 – 500 °C. Hexagonal ZnxCd1-xS films were obtained at 400 °C by varying the precursor concentration. XRD of ZnS films showed cubic to hexagonal phase conversion above 350 °C. SEM showed that the morphology of the films varied depending on the deposition temperature. Films were also characterized by atomic force microscopy (AFM). To the best of our knowledge these complexes are the first in its class to be used as a single molecular precursor to deposit ZnS, CdS, and ZnxCd1-xS thin films.

TaCN-based metal films were grown by metal-organic chemical-vapor deposition (MOCVD) and atomic vapor-deposition (AVD). Thermal decomposition at 500ºC leads to com-positions of approximately Ta0.50C0.4N0.1 (“TaCN”), whereas a reactive process using NH3 leads to the formation of Ta0.65C0.1N0.25 (“Ta2N”) films. All films are nearly amorphous as grown and recrystallize only weakly after spike annealing at 1050°C. The thermal stability of TaCN/HfSiO4 and Ta2N/HfSiO4 stacks during spike annealing at 1050°C was studied and Si and Hf outdiffusion into TaCN or Ta2N was observed. The effective work functions of TaCN and Ta2N on HfSiO4 were found to be as high as 4.9 eV after high thermal budget. It is demonstrated that the effective work function can be further increased to 5.1 eV after high thermal budget by the insertion of a thin Al2O3 capping layer between HfSiO4 and the metal films.

In 1987 samples of Pu238 and Cm244 doped Synroc C were prepared in the UKAEA Laboratories at Harwell. They were studied for five years before being archived. During decommissioning of the Harwell laboratories the samples were transferred to Sellafield and the opportunity was taken to conduct further studies. Given the age of the samples, they offer a unique insight into the long term radiation stability of Synroc. To date, the three Pu238 samples have been examined. The alpha decay dose experienced by the samples is estimated to be 3 × 1019 alphas per gram.

The sample allowed to accumulate alpha decay damage (10587) was slightly heterogeneous, with an apparent grain size in the range 3–15νm. EDX analysis confirmed the phases present to be those expected in Synroc C and that the Pu had partitioned predominantly into the perovskite and zirconolite. Microcracking was observed in the hollandite and rutile but cracks arrested once they reached a zirconolite or perovskite grain.

Sample 10588 was annealed after five years, at temperatures up to 1200°C, this sample was microstructurally similar to 10587 at the 20-50νm scale but differs at small scales. A major difference is the presence of both intergranular and intragranular porosity.

Sample 10589 was annealed at the same time as 10588 but differed significantly probably due to actual fabrication temperatures being higher than those recorded.

Information on these samples will be presented, along with a discussion of the implications for the expected long term stability of titanate ceramic wasteforms.

Elastomeric composites based on Ethylene-Propylene-Diene-Monomer (EPDM) filled with multi-wall carbon nanotubes (MWNTs) have been prepared, showing improved mechanical properties as compared to the pure EPDM matrix. The results have been discussed using the Guth model. The main focus of the study was on the electrical behavior of the nanocomposites, in view of possible sensor applications. A linear relation has been found between conductivity and deformations up to 10% strain, which means that such materials could be used for applications such as strain or pressure sensors. Cyclic experiments were conducted to establish whether the linear relation was reversible, which is an important requirement for sensor materials.

Amorphous LaAlO3 high-k oxide was grown in a molecular beam epitaxy reactor on p-Si(001) using a thin γ-Al2O3 epitaxied buffer layer. Interfaces were free of SiO2 or silicates and remained abrupt despite the high temperature used for annealing, as X-ray photoelectron spectroscopy showed. Electrical measurements performed on as-deposited samples revealed a dielectric constant value close to that of the bulk, small equivalent oxide thickness and low density of interface states. But some negative charges were present, leading to a flat band voltage shift. Post deposition annealing with forming gas can correct this effect.

The decommissioning of the UK’s Magnox reactor sites will produce large volumes of low level waste (LLW) arisings. The vast majority of this waste takes the form of concrete, building rubble and redundant plant containing relatively low levels of radioactivity. Magnox Electric Ltd (Magnox) is leading a strategic initiative funded by the Nuclear Decommissioning Authority (NDA) to explore opportunities for the disposal of such waste to suitably engineered facilities that might be located on or adjacent to the site of waste arising, if appropriate and subject to regulatory acceptance and stakeholder views. The strategic issues surrounding this initiative are described along with an update of progress with stakeholder consultations in relation to the proposed licensing of the first such facility at Hinkley Point A, which could be viewed as a test case for the development of similar disposal facilities at other nuclear sites in England and Wales.

Monolayer thin films of YbBiPt and YBiPt have been produced with 560 nm and 394 nm thick respectively in house and their thermoelectric properties were measured before and after MeV ion bombardment. The energy of the ions were selected such that the bombarding Si ions stop in the silicon substrate and deposit only electronic energy by ionization in the deposited thin film. The bombardment by 5.0 MeV Si ions at various fluences changed the homogeneity as well as reducing the internal stress in the films thus affecting the thermal, electrical and Seebeck coefficient of thin films. The stoichiometry of the thin films was determined using Rutherford Backscattering Spectrometry, the thickness has been measured using interferometry and the electrical conductivity was measured using Van der Pauw method. Thermal conductivity of the thin films was measured using an in-house built 3ω thermal conductivity measurement system. Using the measured Seebeck coefficient, thermal conductivity and electrical conductivity we calculated the figure of merit (ZT). We will report our findings of change in the measured figure of merit as a function of bombardment fluence.

Plasma doping (PLAD) process utilizing PH3 plasma to fabricate n-type junction with supplied bias of −1 kV and doping time of 60 sec under the room temperature is presented. The RTA process is performed at 900 °C for 10 sec. A defect-free surface is corroborated by TEM and DXRD analyses, and examined SIMS profiles reveal that shallow n+ junctions are formed with surface doping concentration of 1021atoms/cm3. The junction depth increases in proportion to the O2 gas flow when the N2 flow is fixed during the RTA process, resulting in a decreased sheet resistance. Measured doping profiles and the sheet resistance confirm that the n+ junction depth less than 52 nm and minimum sheet resistance of 313 Ω/□ are feasible.

We report continuous-wave (CW) infrared-semiconductor laser annealing of silicon implanted with boron atoms with assistance of diamond-like carbon (DLC) films as optical absorption layer in order to form shallow junctions. BF2 ions were implanted at 10 keV at doses of 1.5×1015 cm−2 thorough an 8-nm thick SiO2 layer. The effective boron dose implanted into silicon was 7.5c1015 cm−2 a half of the implantation dose. The initial boron distribution had a peak concentration of 6×1020 cm−3 at the silicon surface and a concentration of 1×1019 cm−3 at a depth of 27 nm. The samples were coated with 200-nm-thick DLC films. The samples were annealed by irradiation with a 940 nm continuous wave laser at 80 kW/cm2 with a beam diameter of 180 μm for 2.6 ms. Heat flow analysis estimated that the sample surface was heated to 1350°C for 1.5 ms by laser annealing. Laser annealing markedly reduced the sheet resistance to 531 Ω/sq. Boron atoms were almost completely activated with a carrier density close to the effective boron dose of 7.5×1014 cm−2. The in-depth profile of boron concentration hardly changed within 3 nm for laser annealing for 2.6 ms. The intermediate SiO2 layer effectively blocked carbon incorporation to a level below 1017 cm−3. These results show that the present laser annealing method is suitable to form shallow junction of a high dopant activation ratio. We will report low energy implantation of boron-cluster ions followed by the present infrared-semiconductor laser annealing in order to form a shallow junction with a depth less than 15 nm.

Singapore, located at the centre of Asia, is an ideal dynamic hub to converge advanced R & D and industry leaders, robust alliances, new technologies and world class infrastructure. In the field of nanotechnology, Singapore is equipped with state of the art facilities (one of the best in the world) for nanotechnology R & D and it has unique open research environment for encouraging and attracting international collaboration and industry cooperation. Combining its efficient government administration and international business and financial environment, Singapore is becoming an attractive place for setting up leading R & D centres, research and development partnerships for research institutions and industries, and for locating company regional headquarters. Singapore government is aggressively promoting innovation and launched attractive funding schemes in help fostering SMEs and spin offs from research institutions. Singapore government has committed SGD 13.55 Billion (USD10B) on R & D for the period of 2006-2010 (over 200% increase from the previous 5 year period), making Singapore GERD to 3% of GDP by 2010. Singapore is not only a melting point of diverse cultures but most importantly a place for exciting converging technologies, global partnerships and creates growth nanotech industries. In this article we give an overview on the Singapore public and private financing schemes for nanotech R & D and commercialisation. Incentives for supporting start-ups as well as R & D partnerships with research institutes are summarized. We outlined the world-class infrastructure for nanotech R & D. Summary of nanotech R & D efforts are highlighted.

The ordered alloy phase of Ti3Al shows a rather wide solid solution range in aluminum and also in vanadium. Several Ti-Al-V ternary alloys have been prepared to investigate the alloy composition effect upon microstructure, crystallography, and mechanical characteristics. The materials containing 75, 70, and 65 at.% titanium, and 0 or 5 at.% vanadium were prepared by arc melting. Metallographic observation has revealed that the binary Ti-Al alloys contained somewhat coarse grains with about 100 μm grain diameter. In contrast to this, ternary alloys containing 5 at.% vanadium showed smaller grained microstructures with grain diameters around 15 μm. The grain size could not be adjusted to a unified value in the present study. X-ray diffraction study and microanalysis showed that the alloys contained single phase α2. Not every possible diffraction peak of the D019 ordered structure has been observed in the XRD patterns. The lattice parameters, a and c, were observed to decrease as the aluminum content increased and also when vanadium was added. Compression tests have been performed at various temperature ranging from an ambient temperature up to 1300K on rectangular parallelepiped specimens with 2mm×2mm×3mm dimensions. Alloys containing more aluminum showed higher strength, and vanadium addition enhanced the strength of the alloys. In some alloys deformability and strength are both enhanced by vanadium addition in some alloys. Temperature dependence of strength showed a little variation upon chemical compositions.

We report on the formation of nanocrystalline Al thin films (180 nm thick) via magnetron sputtering technique using a step-wise deposition concept where columnar growth is inhibited, giving place to the development of a nanocrystalline mosaic grain arrangement with characteristic diameters of ≈ 30 nm and small size dispersion. The thermal evolution of the grain size distributions is investigated by transmission electron microscopy (TEM) in samples annealed in high vacuum for 3600 s. For the temperature range 300 ≤ T ≤ 462 °C the system presents a 3-D regular growth behavior up to sizes ≈ 70 nm. For T = 475 °C a rather sharp transition from normal to abnormal grain growth occurs. The grains extend to the film thickness and present mean lateral dimensions of ≈ 1000 nm. The observed phenomenon is discussed in terms of a synergetic grain boundary mobility effect caused by the characteristics of the initial nanogranular grain boundary morphology.

We have proposed a new mixed approach by combining efficiently classical and first-principles molecular dynamics to study undercooling of liquid silicon, regardless of a specific empirical interaction model. Our results show an enhancement of the local tetrahedral ordering in the deep undercooled region associated to the appearance of propagating shear waves and give a strong support to the existence of a transition between a high density liquid to a low density liquid near 1050 K. An analysis of the structural, dynamics and electronic properties is proposed to elucidate these features.

The electronic properties of an InN/anatse bilayer, proposed as a replacement for the dye/semi-conductor interface in Dye Sensitized Solar Cell[1, 2], are measured. RF sputtered thin films of anatase and InN are used as the “dye” replacement. .Two types of InN film are prepared: polycrystalline samples deposited at high temperature, with an optical band gap of < 1 eV, and as-deposited (at least partially amorphous) samples with an optical band gap >1 eV.Energy Dispersive X-ray fluorescence, X-ray Diffraction, and Raman spectroscopy are used to characterize the samples. The resistance in the dark and under illumination are measured.The samples deposited at high temperature are crystalline and have a sheet resistivity ≈ 4 Ω/⁐, and display no photoconductivity.The partially amorphous samples have sheet resistivity of≈ 500Ω/⁐. Since both types of InN films, including high quality (based on band gap) polycrystalline InN, do not show increased conductivity with light, we conclude that a solar cell based on an InN/anatase bilayer is not feasible.

While only a minor phase constituent, the deformation behavior of the hexagonal α2-Ti3Al phase, significantly affects the mechanical properties of two-phase TiAl based alloys. We have used conventional and high-resolution transmission electron microscopy to investigate the fine structure of pyramidal plane glide dislocations, with Burgers vectors of the type b=<2c+a>, in α2-Ti3Al after room temperature compression of binary polysynthetically twinned TiAl normal to the lamellar interfaces to nominal plastic strains of 1%-7%. We report atomic resolution observations of non-co-planar dislocation core configurations for <2c+a>-dislocations and show that translamellar deformation twins active in the majority γ-TiAl phase play an important role in facilitating pyramidal plane slip in α2-Ti3Al in the lamellar two-phase alloys.

It is shown that solution-grown ZnO nanostructures exhibit enhanced radiation hardness against neutron irradiation as compared to bulk material. The decrease of the cathodoluminescence intensity after irradiation at a neutron dose of 6 × 1016 cm−2 in ZnO nanostructure is nearly identical to that induced by a dose of 1.5 × 1014 cm−2 in bulk material. The damage introduced by irradiation is shown to change the nature of electronic transitions responsible for luminescence. The change of excitonic luminescence to the luminescence related to the tailing of the density of states caused by potential fluctuations occurs at an irradiation dose around 6×1016 cm−2 and 5×1014 cm−2 in nanostructured and bulk materials, respectively.

Hall measurements before and after annealing determined the effect of dose on resistance, mobility, and carrier concentration. Annealing decreased the sheet resistance, increased the mobility, and increased carrier concentration for all doses. While the concentration of carriers in the control sample increased 200-fold after annealing, the increase was ∼1000-fold for the irradiated samples. Annealed irradiated samples showed a maximum carrier concentration increase of about 60x over the unirradiated sample. Interestingly, neutron irradiation increased the mobility even in the un-annealed samples.

Topochemical reaction strategies based on two-step intercalation methods are studied. Reactions involving reductive followed by oxidative intercalation are quite effective in making new compounds; the synthesis and characterization of (A2Cl)LaNb2O7 (A = Rb, Cs) are presented. An alternative synthetic route, oxidative followed by reductive intercalation, is also discussed.

The long-term prediction of the equilibrium concentration of α-isosaccharinic acid (α-ISA) in cement pore water is a crucial step in the assessment of the role of cellulose in the safety of a cementitious repository. The aim of the present contribution is to summarise recent efforts in identifying the most important processes leading to the formation or degradation of α-ISA and in predicting its most likely concentrations in cement pore water. The issues considered are the kinetics involved in the formation of α-ISA, reactions of α-ISA with dissolved or solid compounds that may lead to limitations of its pore water concentrations and the chemical stability of α-ISA in a heterogeneous alkaline environment. Some new results are presented showing that α-ISA is degraded to low-molecular weight organic compounds in the presence of oxygen, whereas such processes occur only to a minor extent under anaerobic conditions. It is concluded that the processes involved in the degradation of cellulose under alkaline conditions are not sufficiently understood to explain fully the observed concentrations of α-ISA in long-term experiments.

Micro tubular solid oxide fuel cells (SOFCs) have many desirable advantages compared to general SOFC. Recently, microtubualr SOFC are now studied to apply into APU system in a future generation vehicles. In this study, electrochemical and mechanical properties of the micro tubular SOFCs (less than 1 mm O.D.) have been characterized. Electrochemical characterization showed the excellent performance of MT SOFC with the power density of 1 W/cm2 at 600°C. Impedance measurement indicated that the contribution of contact resistance on the cell performance was still high and there were many possibilities to improve the cell performance. Mechanical test of the MT-SOFC using burst testing apparatus indicated the mechanical properties were mainly dependent on porosity and wall thickness, i.e. physical properties of anode support. This study examined the properties of micro-tubular SOFC using the novel characterization method for APU application.

Detection of mercury with high sensitivity and selectivity constitutes a significant research concern. Here, we report an amplified fluorescence turn-on assay for mercury(II) with an improved performance. This sensing system takes advantage of optically amplifying fluorescent conjugated polyfluorene derivatives and DNA immobilized silica nanospheres (NSs) in addition to the specific thymine- mercury(II)-thymine(T- Hg2+-T) interaction. The employment of ion-specific T- Hg2+-T coordination increases the melting temperature (T m) of the double-stranded DNA (dsDNA) on the hybridized NS surface. After thermal washing at 45 °C, the Hg2+ treated sample (dsDNA-NS) was effectively differentiated from that treated with nonspecific ions through monitoring fluorescence emission of fluorescein (Fl) labeled target DNA remained on the NS surface. Finally, a cationic conjugated polyfluorene derivative (CCP) was introduced to electrostatically associate with the DNA molecules on the NS surface, resulting in an amplified Fl signal via fluorescence resonance energy transfer (FRET) from the CCP to the dye molecule. In comparison with the use of Fl alone as a signal reporter, the presence of CCP significantly enhances the detection fluorescence intensity, reduces false-positive signal, and improves the detection selectivity for mercury(II). Further improvement in the probe design could yield more efficient metal ion sensors, which have the potential to be operated at room temperature and for the detection of other metal ions besides mercury(II).