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Showing papers on "Potassium iodate published in 1999"


Journal ArticleDOI
TL;DR: In this paper, the authors investigated aspects of the kinetics of tungsten chemical mechanical polishing (CMP) in iodate-based slurries and found that the polish rate data fit a multiterm regression model better than the empirical Preston equation.
Abstract: We investigated aspects of the kinetics of tungsten chemical mechanical polishing (CMP) in iodate‐based slurries. Specifically, we performed experiments in which we measured the tungsten polish rate and process temperature as a function of alumina concentration, potassium iodate concentration, platen temperature, polish pressure, polish rotation rate, and pad type. We found that the polish rate data fit a multiterm regression model better than the empirical Preston equation. Polish rate was found to vary with all of the factors investigated. Process temperature varied with all of the factors except potassium iodate concentration. These results, in combination with an energy balance on the entire process, indicate the change in temperature due to alumina concentration is mostly due to energy input from increased shaft work. This implies that the chemical and physical interactions between the alumina and tungsten surfaces are complex and play an important role in the mechanism of tungsten removal during CMP. © 1999 The Electrochemical Society. All rights reserved.

57 citations


Journal ArticleDOI
TL;DR: In this paper, the role of colloid species and slurry chemistry in tungsten chemical mechanical polishing was investigated, and it was shown that the colloid surface chemistry had a large effect on polish rate and process temperature, however, the trend in polish rate did not always follow that of process temperature.
Abstract: We investigated the role of colloid species and slurry chemistry in tungsten chemical mechanical polishing. Specifically, we measured polish rate and process temperature in potassium iodate-based slurries as a function of colloid species and concentration, slurry pH, and potassium iodate concentration, as well as polish pressure and polish rotation rate. We investigated slurries containing yttrium-, zirconium-, cerium-, and aluminum-based oxide and hydroxide colloids. We found that the colloid species had a large effect on polish rate and process temperature. The colloids showed two orders of magnitude in the polish rate range from ∼15 to ∼1975 A min -1 under otherwise identical experimental conditions (same polisher, pad, slurry chemistry, pressure, and rotation rates). Colloids of the same metal species from different sources also showed a large range in polish rates. Process temperature was a function of colloid species, however, the trend in polish rate did not always follow that of process temperature. Both polish rate and process temperature were dependent on potassium iodate concentration and slurry pH (controlled with a buffer). We also introduce a heuristic polish mechanism to investigate the role of the colloid surface chemistry and its interaction with the tungsten surface. The data indicate that the surface characteristics of the colloid and how this surface interacts with the tungsten surface play a significant role in the mechanism of tungsten removal during polish.

39 citations


Journal ArticleDOI
TL;DR: Simultaneous spectrophotometric and volumetric determinations of the antibiotic is based on the neutralization of the degraded product by dilute hydrochloric acid to get a pH approximately 2 to be conducive for redox titration using potassium iodate as titrant.

33 citations


Journal ArticleDOI
TL;DR: In this paper, the results of a thorough study and application of leucocrystal violet for the determination of arsenic in parts per million (ppm) levels in environmental and biological samples is described.
Abstract: Results of a thorough study and application of leucocrystal violet for the determination of arsenic in parts per million (ppm) levels in environmental and biological samples is described here. The proposed method is based on the reaction of arsenic with potassium iodate to liberate iodine. The liberated iodine selectively oxidises leucocrystal violet to form crystal violet dye in the presence of sodium hydroxide. The dye formed shows maximum absorbance at 592 nm. The detection limit of arsenic is 0.002 μgmL−1 and the method obeys Beer's law over the concentration range of 0.1 μg - 1.0 μg of per 25 mL of final solution (0.004–0.04 ppm). The molar absorptivity was found to be 1.49 × 106 L mol−1 cm−1. The proposed method was successfully applied for the determination of arsenic in various environmental and biological samples. The results are in good agreement with the standard reported method.

20 citations


Journal ArticleDOI
TL;DR: In this paper, two experiments were conducted to evaluate surface applications of potassium iodide and potassium iodate as alternatives to direct treatment of ewes where iodine deficiency may be a problem.
Abstract: Two experiments were conducted to evaluate surface applications of potassium iodide and potassium iodate as alternatives to direct treatment of ewes where iodine (I) deficiency may be a problem. In Experiment 1, the hypothesis that grazing of pasture which had been sprayed with a potassium iodide and oil mixture results in increased blood iodine (serum T4) levels in ewes was tested over two years on five farms in Southland and West Otago, New Zealand. The results show that spraying elevated pasture I levels from March to pre lambing. The increased pasture I levels increased serum T4 levels by only 1.5% in late winter, an increase which was not significant (P > 0.05). There were small increases in lambing percentages (1–5%) due to the spraying in both years, but these were not significant (P > 0.05). In Experiment 2, the hypothesis that surface applications of potassium iodide and potassium iodate fertiliser can result in increased herbage I levels was tested on two farms in Southland and West Ota...

12 citations