Papers by Keyword: NH₄OH

Abstract: A new process was provided for decomposition of ilmenite by ammonium hydroxide under hydrothermal process. The significant effects of reaction temperature, NH₄OH concentration, NH₄OH-to-ilmenite mass ratios on titanium extraction were studied. The temperature showed significant influence on titanium extraction. The experimental data of the extraction rates under the relevant operating variables were well interpreted with the shrinking core model under chemically controlled process.

Abstract: The Magnesium hydroxide sulfate hydrate whiskers (5Mg(OH)₂.MgSO₄.3H₂O, abbreviated 513MHSH) have attracted much attention due to its practical applications as filler and reinforcement. However, it is difficult to produce high quality MHSH because plate-like Mg(OH)₂ impurities were formed in high concentrations of OH^- and interaction between Mg²⁺ and OH^-. In this work, to reduce formation Mg(OH)₂, molar ratio of^{Superscript text} magnesium oxide (MgO) and magnesium sulfate (MgSO₄.7H₂O) were controlled. As a result, when low concentration of SO₄^2-, MHSH whiskers co-existed with hexagonal plate Mg(OH)₂. The molar ratio of MgSO₄.7H₂O/MgO was high, uniform MHSH whiskers were formed without Mg(OH)₂. In addition, appropriate amount of NH₄OH has affected formation of high quality MHSH. Their morphologies and structures were determined by powder X-ray diffraction (XRD) scanning electron microscopy (SEM) and thermo-gravimetric analyzer (TGA)

Abstract: The porous TiO2 layer on the silicon surface not only acts as a buffer layer to relieve the strain associated with the volume expansion but also prevents the aggregation of the particles upon normal cycles of charging and discharging. The control of the optimum amount of catalyst has led to enhance the cycle performance of TiO2 coated silicon anode.

Abstract: One of key processes in tungsten (W) CMP is to remove slurry particles inside W plug after CMP. In general, HF cleaning is well known to remove the slurry residue particles in W plugs. HF chemistry lifts off the particles by etching the plug during scrubbing and effectively removes particles. It is sometimes impossible to apply HF chemisty on W plug due to the degradation of electrical characteristics of a device. In this paper, a post W CMP cleaning process is proposed to remove residue particles without applying HF chemistry. After W CMP, recessed plugs are created, therefore they easily trap slurry particles during CMP process. These particles in recessed plug are not easy to remove by brush scrubbing when NH4OH chemistry is used for the cleaning because the brush surface can not reach the recessed area of plugs. Buffing with oxide slurry was followed by W CMP due to its high selectivity to W. The buffing polishes only oxide slightly which creates higher plug profiles than surrounding oxide. Higher profiles make the brush contact much more effectively and result in a similar particle removal efficiency even in NH4OH cleaning to that in HF brush scrubbing.