Title

The decomposition of the environmental pollutant, nitrogen trifluoride, and the synthesis of catalysts using microwave heating

Date of Completion

January 1998

Keywords

Chemistry, Inorganic|Environmental Sciences|Engineering, Environmental|Engineering, Materials Science

Degree

Ph.D.

Abstract

In the past decade, the use of NF$\sb3$ has increased dramatically. This is due to the development of NF$\sb3$ as an etching and cleaning agent in the semiconductor industry. The development of a plasma method that can enhance reaction selectivity while at the same time reducing damage and contamination has become increasingly important with the increased sophistication of integrated circuit technology. NF$\sb3$ has managed to fill this role. However, concerns regarding its toxicity and its environmental effects as a greenhouse gas has spurred the development of new processes to destroy or remove unreacted effluent NF$\sb3.$^ The research presented here is an attempt to evaluate suitable gettering materials to establish a strong scientific basis for the rational choice of gettering materials. This is the first step in the design of an effective, cost efficient system to eliminate or recycle unreacted effluent NF$\sb3$ in a manner that is environmentally friendly and safe. Metal oxides, metals, and mixed systems were tested under similar conditions.^ Interactions of microwaves and materials has proven to be a fascinating field of materials synthesis. Recent literature articles concerning the use of microwave heating to produce organic and inorganic materials has demonstrated the unique capabilities that microwave radiation possesses. Reactions using shorter times and producing more crystalline products are two hallmarks of microwave heating, as well as stereochemically selective organic reactions with and without solvent and/or catalysts.^ There is a current debate as to whether an intrinsic microwave effect exists or if the rapid crystallization and shorter processing times are simply due to extremely localized heating or inaccurate temperature measurement. This work presents a study of the synthesis of manganese oxides using microwave heating, and compares the products obtained to those prepared using conventional heating in an attempt to understand the phenomenon. Manganese oxides were chosen because they are known to absorb microwave radiation well, indicating that synthesis of manganese oxides in a microwave field might lead to different and interesting results, and give insight to some of the phenomenon associated with microwave heating. ^