Dissertation
POLYMERIZATION OF CARBON MONOXIDE, HYDROGEN-CARBON MONOXIDE MIXTURE, AND IRON PENTACARBONYL AT HIGH PRESSURE: SYNTHESIS OF HIGH ENERGY DENSITY EXTENDED CO SOLID AMENABLE TO STABILIZATION AT AMBIENT PRESSURE
Doctor of Philosophy (PhD), Washington State University
01/2016
Handle:
https://hdl.handle.net/2376/111839
Abstract
The application of high pressures to low-Z molecular solids can transform them into non-molecular extended solids of three-dimensional network structures with atoms bound by strong covalent bonds. These extended solids often exhibit novel properties such as superhardness, high-temperature superconductivity, ferroelectricity, multi-ferroicity, and high energy density. However, their limited stability under ambient conditions pose a challenge for such materials to be used in any application. Thus, our goal is to develop novel extended solids amenable to scale-up synthesis and stabilization at the ambient conditions.
Carbon monoxide furnished one such example of a low-Z molecular solid. It was the first molecular system found to transform above 5.5 GPa into a non-molecular “polymeric” solid in high energy density. The structure and properties of these phases above this pressure, however, had not been thoroughly investigated. For this reason, we have first investigated the pressure-induced phase transformations of carbon monoxide have been investigated to 160 GPa and found a series of transformations from molecular CO to opaque polymeric phase I at 6.3 GPa, then to translucent phase II at 11 GPa and transparent phase III above 50 GPa. These polymeric phases are recoverable, but highly metastable at ambient conditions. Then, we have investigated the effect of doping hydrogen or iron atoms on the stability of polymeric CO at ambient conditions.
We have investigated the physical and chemical transformations of binary mixtures of carbon monoxide and hydrogen using various spectroscopic methods with diamond anvil cell, Paris-Edinburg large volume anvil cell and Bridgman anvil cell. The results revealed that different doping ratio hydrogen molecule in carbon monoxide promote polymerization at low pressures and enhance the stabilization of recovered polymeric products.
The effect of iron on polymeric CO has been investigated through high-pressure studies on iron pentacarbonyl with weak Fe-CO back-bonds. The results indicates that the phase diagram of Fe(CO)5 consists of three molecular polymorphs (phase I, II and III) and an extended polymeric phase that can be recovered at ambient condition. The phase diagram shows a limited stability of Fe(CO)5 within a pressure-temperature dome formed below the liquid- phase II- polymer triple point at 4.2 GPa and 580 K. The limited stability, in turn, signifies the temperature-induced weakening of Fe-CO back bonds, which eventually leads to the dissociation of Fe-CO at the onset of the polymerization of CO. The recovered polymer is a composite of novel nm-lamellar layers of crystalline hematite Fe2O3 and amorphous CO polymers. These results, therefore, demonstrate the synthesis of Fe-doped CO polymer by compressing Fe(CO)5, which advocates a novel synthetic route to develop atomistic composite materials by compressing organometallic compounds.
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Details
- Title
- POLYMERIZATION OF CARBON MONOXIDE, HYDROGEN-CARBON MONOXIDE MIXTURE, AND IRON PENTACARBONYL AT HIGH PRESSURE: SYNTHESIS OF HIGH ENERGY DENSITY EXTENDED CO SOLID AMENABLE TO STABILIZATION AT AMBIENT PRESSURE
- Creators
- YOUNG JAY RYU
- Contributors
- Choong-Shik Yoo (Advisor)Kerry W Hipps (Committee Member)James A Brozik (Committee Member)Christian Mailhiot (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Materials Science and Engineering Program
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 178
- Identifiers
- 99900581431301842
- Language
- English
- Resource Type
- Dissertation