This work explores the synthesis and characterization of the metastable alloys Sn1-xCaxCh (Ch= S, Se) and nitride compounds Zn-W-Mo-N, which have recently been predicted by theorists. Single phase thin films of Sn1-xCaxS are prepared by pulsed laser deposition and radio-frequency magnetron sputtering and of Sn1-xCaxSe are prepared by pulsed laser...
Phosphate and peroxide stabilize new oxo-hydroxo niobium clusters in water at low pH. The clusters open a new chapter in aqueous niobium chemistry under acidic conditions. The clusters also produce atomically smooth, amorphous niobium oxide phosphate (NbPOx) thin films. Reaction pathways from cluster solutions to amorphous niobium oxide phosphate solids...
Oxo-hydroxo Group 5 metal clusters are an untapped resource to study and advance aqueous solution processing of metal oxide thin films. The tetramethylammonium (TMA) hexatantalate salt (TMA6[H2Ta6O19]) yields dense Ta2O5 films (~95% of the bulk ß-Ta2O5 density) with atomically smooth surfaces (<4 Å root mean square surface roughness). This same...
Chemistry of preparing dense film from solution deposition is explored with several cases in this thesis. Surface dense structure, conversion at melting point, and ion exchange in aqueous solution are the main topics covered here for the thin films of aluminum oxide phosphate and tin dioxide. Thin film density, optical...
The development of nanomaterials and the potential enhancement of their chemical, mechanical, electrical, and optical properties have led to the investigation of methods for their synthesis at lower cost with enhanced performance for next generation devices. Along with the pursuit of new materials that exhibit properties of interest, industry requires...
Polyoxometalates are a rapidly growing class of discrete metal oxide clusters with a wide range of applications including functional materials. These anionic clusters of the group V and VI transition metals are inexpensive and non-toxic. Within group V polyoxometalates, niobium and tantalum chemistry has been underdeveloped owing to their unique...
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May Nyman
Polyoxometalates are a rapidly growing class of discrete metal oxide clusters
Changes in climate caused by increased concentrations of carbon dioxide (CO₂) in the Earth’s atmosphere have led land and ocean surface temperatures to increase by 0.85°C and sea level to increase by 19 cm relative to preindustrial times. Global climate change will lead to further alterations in mean temperature and...
The focus of this thesis is developing materials for thin-film transistors (TFTs). Cu₃SbS₄ is explored as p-channel layer. Cu₃SbS₄ TFTs show p-type, depletion-mode behavior with a small amount of gate-controlled modulation of the channel conductance. This behavior is consistent with Hall measurements indicating a mobility of 17 cm²V⁻¹s⁻¹ and hole...
Emergence of a terawatt scalable photovoltaic (PV) thin film technology is currently impeded by
the limited supply of relatively rare elements like In or Te, which has spurred active research in
recent years on earth-abundant PV materials. Instead of searching for alternative PV materials,
we approach the problem here by...
Mixed anion compounds that form ZrCuSiAs-type crystal structures exhibit remarkable properties such as superconductivity at low temperatures,
hole conduction with optical transparency in the visible region, and exciton absorption at room temperature. In this thesis, properties of a selected group of materials out of the very large set of mixed...