In this paper we report the observation of enhanced field emission properties from thiolated multi-wall carbon nanotubes (MWCNTs) produced by a simple and effective two-step chemical surface modification technique. This technique implements carboxylation and thiolation on the MWCNTs synthesized by microwave plasma chemical vapor deposition (MPCVD) on the flexible carbon cloth substrate. The resulting thiolated MWCNTs were found to have a very low threshold field value of 1.25 V µm(-1) and a rather high field enhancement factor of 1.93 × 10(4), which are crucial for applications in versatile vacuum microelectronics.
The phase transformation in Zn-4 Al-3 Cu alloy employing various solution-treatment temperatures (230 ЊC to 325 ЊC) was studied by means of microhardness, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The starting microstructure of the as-cast Zn-4Al-3Cu alloy consists of an ␣ phase (aluminum-rich, fcc structure) in the matrix (zinc-rich, h.c.p. structure) prior to solution-treatment. A platelike ε phase with 3-m length and 0.5-m thickness was found in the phase matrix after solution-treating the as-cast material at 240 ЊC for 1 hour. The ε phase was then dissolved gradually back into the matrix above that temperature. A four-phase transformation, ␣ ϩ ε → T' ϩ , was observed from the temperature 250 ЊC to 310 ЊC, wherein the T' phase formed at the interface of ε platelet and phase matrix. This T' phase was further identified as a rhombohedral structure. As the solution-treatment temperature was increased to above 310 ЊC, the ε phase was completely dissolved back into the matrix and numerous  phase particles were distributed uniformly in the matrix. The  phase subsequently decomposed at room temperature to a fine ␣ phase embedded in the matrix. For the materials solution-treated above 250 ЊC, the microhardness of the matrix increased in 40 minutes during natural aging, which was associated with the formation of fine ε phase of 0.15-m diameter. The orientation relationship between this fine ε phase and phase was determined as [ 011] // [ 011] ε , (01 2) // (01 2) ε . 1 1 1 1
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