Synthesis of cadmium (Cd)-free quantum dots (QDs) with tunable emission and high color purity has been a big challenge for the academic and industrial research community. Among various Cd-free QDs, indium phosphide (InP) QDs exhibit reasonably good color purity with emission full width at half-maximum (fwhm) values between 45 and 50 nm for green and over 50 nm for red emission, which is not good enough, as values less than 35 nm are favorable in commercial display products. In this work, we present the synthesis of highly luminescent In­(Zn)­P/ZnSe/ZnS QDs with tunable emission from 488 to 641 nm and high color purity. We found that the addition of zinc during the conventional SILAR growth of shell (ZnSe or ZnS) deteriorated the absorption features of core InP QDs and resulted in broader emission line widths. We solved this issue by synthesizing Zn carboxylate covered In­(Zn)P QDs in a single step and dramatically decreased the emission fwhm to as low as 36 nm with quantum yields (QYs) up to 67% for the green emitting QDs. We also demonstrate an effective successive ion layer adsorption and reaction method to continuously tune the InP QDs size from 1.6 to 3.6 nm with narrow size distribution. This enables us to tune the emission up to 641 nm with fwhm values less than 45 nm and QY up to 56% for red emission. This is the first report on the synthesis of InP QDs with such high color purity. In addition, the obtained QDs show exceptional stability under air (>15 days) and heat treatment (150 °C in air for 24 h). Given the difficulty in synthesizing size tunable InP QDs with narrow emission fwhm and high quantum yield, the results presented here are an important step toward the realization of Cd-free QDs as a feasible alternative in commercial display technologies.

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Inclusions chemistry of Mn/Si deoxidized steel was studied through both thermodynamic computation and experimental method. The computational thermodynamics has proved to provide a powerful tool for controlling inclusions and precipitates in steel. For Mn/Si deoxidized steels, important factors in determining the liquidus temperature and primary phase of the inclusions are MnO/SiO 2 ratio and Al 2 O 3 content in inclusions. Provided that no further interaction with steel matrix during cooling, inclusions having MnO/SiO 2 mass% ratio near unity and Al 2 O 3 content in the range of 10-20 mass% give low liquidus temperatures (1150-1200°C) and primary phases of MnSiO 3 and Mn 3 Al 2 Si 3 O 12 both which are soft. For the case of MnϩSiϭ1.0 in mass%, the Mn/Si ratio of 2-5 meets the above conditions. Effect of the top slag on the inclusions chemistry can be predicted with accuracy, and hence it is possible to control the inclusions chemistry through proper design of the top slag composition so that the inclusions show a low liquidus temperature and soft primary phase. As the inclusions composition gradually changes with time toward the top slag composition, the length of refining time which determines the extent of reaction with the top slag is an important factor in determining the inclusions chemistry.KEY WORDS: inclusion; Mn/Si deoxidation; metal-inclusion reaction; the CaO-MnO-SiO 2 -Al 2 O 3 system; computational thermodynamics. namic computations, a thermodynamic database for slag and inclusion, which was optimized by the present authors, [19][20][21] was used, and all calculations were performed using the FactSage thermochemical software. 22) Thermodynamic Basis-Models and Database Liquid SteelMost investigators have used interaction parameter formalism developed by Wagner 23) and extended by Sigworth and Elliot. 24) This formalism has been widely used in metallurgy to calculate activity/activity coefficients of solutes in liquid steel. Many experiments have been conducted to evaluate interaction parameters among metallic elements, O, C, S, N etc. in molten iron and are well documented in the literature. 24,25) However, it fails sometimes to reproduce experimental data, particularly for those cases of 1) a highly concentrated region or 2) containing strong deoxidizer such as Al, Ca and Mg. In order to solve these problems in a thermodynamically sound way, Pelton and Bale 26-28) developed Unified Interaction Parameter Formalism (UIPM) which modifies Wagner formalism 23,24) and Darken formalism. 29) Moreover, in order to reproduce the deoxidation phenomena when strong deoxidizing elements exist, Jung et al. 30) proposed the use of associates such as Al*O, Ca*O, Si*O etc. in molten iron with UIPM. This UIPM with associates shows excellent agreement between calculation and experiments for deoxidation phenomena in liquid steel with a few model parameters. 30) Therefore, UIPM with associates was used to describe thermodynamic properties for liquid steel. All interaction parameters required for deoxidation of Mn, ...