Non-hydrolytic Sol-gel (NHSG) Synthesis of Transition Metal Sulfides and Theoretical Investigations
type: CreativeWork
description: Non-hydrolytic sol-gel (NHSG) synthesis provides an elegant approach to many solid-state materials, which was originally developed for the preparation of oxides.1 As they do not require high temperatures like conventional solid-state routes, access to thermodynamically metastable materials, which cannot be prepared through traditional solid-state routes, is possible. In this project, NHSG chemistry is explored for the synthesis of binary metal sulfides.Sulfides, some of which are thermally unstable and highly oxygen sensitive, have applications in many areas, such as solar cells, catalysts, sensors, lubricants, semiconductors etc.2 Despite the widespread use of sulfides, they have been studied much less comprehensively than oxides. One of the reasons is the difficulty in synthesis because metastable sulfides are intolerant to high temperatures and oxygen. In NHSG routes, the reaction of a metal halide with a thioether is used to form a metal sulfide network at low temperatures. This can give access to materials that are not accessible by high temperature routes, and may lead to the discovery of new phases.3 Because synthesis of sulfides through NHSG is an unexplored area, the synthesis conditions must be optimized for each metal. In this thesis, the Cu-S and Ta-S systems were thoroughly explored using NHSG techniques. Amorphous tantalum sulfides were obtained in as-recovered samples, and heat treatments of such amorphous precursors resulted in crystallization of 1-TaS2 and 3R-TaS2 phases. For the synthesis of copper sulfides, precise phase selection of five different polymorphs, metastable hexagonal chalcocite, monoclinic chalcocite, djurleite, low digenite and covellite, was achieved by fine tuning synthetic parameters. In addition, a continuous phase evolution from copper rich phases towards copper deficient phases between chalcocites and djurleite was observed. All polymorphs could be obtained as nanoparticles. Theoretical studies can complement experimental appr…
abstract: Non-hydrolytic sol-gel (NHSG) synthesis provides an elegant approach to many solid-state materials, which was originally developed for the preparation of oxides.1 As they do not require high temperatures like conventional solid-state routes, access to thermodynamically metastable materials, which cannot be prepared through traditional solid-state routes, is possible. In this project, NHSG chemistry is explored for the synthesis of binary metal sulfides.Sulfides, some of which are thermally unstable and highly oxygen sensitive, have applications in many areas, such as solar cells, catalysts, sensors, lubricants, semiconductors etc.2 Despite the widespread use of sulfides, they have been studied much less comprehensively than oxides. One of the reasons is the difficulty in synthesis because metastable sulfides are intolerant to high temperatures and oxygen. In NHSG routes, the reaction of a metal halide with a thioether is used to form a metal sulfide network at low temperatures. This can give access to materials that are not accessible by high temperature routes, and may lead to the discovery of new phases.3 Because synthesis of sulfides through NHSG is an unexplored area, the synthesis conditions must be optimized for each metal. In this thesis, the Cu-S and Ta-S systems were thoroughly explored using NHSG techniques. Amorphous tantalum sulfides were obtained in as-recovered samples, and heat treatments of such amorphous precursors resulted in crystallization of 1-TaS2 and 3R-TaS2 phases. For the synthesis of copper sulfides, precise phase selection of five different polymorphs, metastable hexagonal chalcocite, monoclinic chalcocite, djurleite, low digenite and covellite, was achieved by fine tuning synthetic parameters. In addition, a continuous phase evolution from copper rich phases towards copper deficient phases between chalcocites and djurleite was observed. All polymorphs could be obtained as nanoparticles. Theoretical studies can complement experimental appr…
author: Zhou, Xiuquan
language: English
keywords: Chemistry
date published: 2013-06-14
date modified: 2026-07-24T03:37:16Z
provider: OhioLINK
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Toledo