THE FABRICATION OF NANOMETRIC METAL SULFIDES FROM XANTHATE PRECURSORS By ALAN PIQUETTE Bachelor of Arts Western State College of Colorado Gunnison, Colorado 2002 Submitted to the Faculty of the Graduate College of the Oklahoma State University In partial fulfillment of The requirements for The Degree of DOCTOR OF PHILOSOPHY December, 2007 THE FABRICATION OF NANOMETRIC METAL SULFIDES FROM XANTHATE PRECURSORS Thesis Approved: _______________ __Allen Apblett___ ______________ Thesis Advisor ________________ Nicholas Materer_____ __________ _____________ __LeGrande Slaughter___ __________ _______________ ____Jim Smay___ _______________ _____________ __A. Gordon Emslie___ ____________ Dean of the Graduate College ACKNOWLEDGEMENTS It is with my utmost sincere appreciation that I acknowledge my thesis advisor, Dr. Allen W. Apblett, for his support, guidance, and motivation. He provided a research environment that was both friendly and challenging, which made my years in his group enjoyable and rewarding. His broad range of knowledge was something of which I was happy to take advantage. His dedication to teaching and research is something that will be a positive influence on me for the rest of my scientific career. I would like to express gratitude to my committee members: Dr. Nicholas Materer, Dr. LeGrande Slaughter, and Dr. Jim Smay, for their assistance, advice, guidance, and support throughout the years. I am deeply grateful to all my colleagues and friends in the chemistry department. I would specifically like to thank Sulaiman Al-Fadul, Mohammed Al-Hazmi, Zeid Al- Othmann, Mohamed Chehbouni, Satish Kuriyavar, and Tarek Trad for showing me the ropes, for their valuable discussions, continuous encouragement, and for all the help they extended during the course of my stay in the Apblett Group. It would not have been the same without you. iii I am also thankful to all the faculty and staff at the Department of Chemistry at Oklahoma State University for their help and kindness. I am deeply indebted to my siblings: Eric, Jeff, Paul, Megan, and Evan for their unwavering love, support, and friendship. Words cannot express how appreciative of my parents I have been throughout my life. Without them, I would be lost. Finally, I humbly thank God, to whom I owe everyting. iv TABLE OF CONTENTS CHAPTER PAGE CHAPTER 1 INTRODUCTION ............................................................................................................. 1 Introduction to dissertation ..................................................................................... 1 Collaboration................................................................................................1 Dissertation outline ......................................................................................1 Motivation and scope of the research ..................................................................... 2 Basic motivation ..........................................................................................2 Importance of nanometric metal chalcogenides ..........................................2 Various routes to semiconductor nanoparticles ...........................................4 Summary of Results.............................................................................................. 10 Part one ......................................................................................................10 Part two ......................................................................................................10 Part three ....................................................................................................12 CHAPTER 2 SYNTHESIS, CHARACTERIZATION AND APPLICATIONS OF METAL XANTHATE COMPOUNDS .................................................................................. 13 Introduction........................................................................................................... 14 Experimental......................................................................................................... 16 Materials ....................................................................................................16 Synthesis of group I ethylxanthates ...........................................................17 Synthesis of various potassium alkylxanthate compounds........................18 v CHAPTER PAGE Synthesis of transition metal ethylxanthates..............................................21 Characterization .........................................................................................23 Results and Discussion ......................................................................................... 24 Structure and thermal stability of alkali metal ethylxanthates...................24 Structure and thermal stability of transition metal ethylxanthates.............32 Tailoring the xanthate substituent for specific purposes............................36 References............................................................................................................. 40 CHAPTER 3 SINGLE PRECURSOR ROUTE TO SULFIDES: INFLUENCE OF THE METAL AND R-GROUP IN THE DECOMPOSITION OF ALKYLXANTHATES ...... 44 Introduction........................................................................................................... 45 Experimental......................................................................................................... 47 Materials ....................................................................................................47 Synthesis of potassium alkylxanthates.......................................................47 Synthesis of transition metal alkylxanthates..............................................49 Characterization .........................................................................................50 Results and Discussion ......................................................................................... 51 Metal influence: thermogravimetric analysis and decomposition products......................................................................................................51 Alkyl group influence: thermogravimetric analysis and decomposition products .............................................................................60 Conclusions........................................................................................................... 69 References............................................................................................................. 71 CHAPTER 4 LOW TEMPERATURE GROWTH OF ZINC SULFIDE NANOPARTICLES FROM ZINC XANTHATE SINGLE SOURCE PRECURSORS ....................... 73 vi CHAPTER PAGE Introduction........................................................................................................... 74 Experimental......................................................................................................... 75 Materials ....................................................................................................75 Synthesis of ZnS suspensions in DMSO ...................................................75 Characterization .........................................................................................76 Results and discussion .......................................................................................... 79 Preparation of ZnS nanoparticles from Zn(S 2COCH 2CH 3)2......................79 The decomposition of Zn(S 2COCH 2CH 3)2 ................................................83 DMSO bonding in the ZnS-DMSO complex.............................................88 Conclusions........................................................................................................... 95 References............................................................................................................. 97 CHAPTER 5 BROADBAND LUMINESCENCE FROM HIGH SURFACE AREA ZINC SULFIDE AND ZINC OXIDE.............................................................................. 100 Introduction......................................................................................................... 101 Experimental....................................................................................................... 102 Materials ..................................................................................................102 Synthesis of neat ZnS, doped ZnS, and ZnO...........................................103 Characterization .......................................................................................104 Results and Discussion ....................................................................................... 106 Thermogravimetric anaylsis of Zn(S 2COCH 2CH 3)2 and powder X-ray diffraction patterns of the solid decomposition products ..............106 Surface area analyses of ZnS and ZnO nanocrystals...............................110 Fluorescence spectra of ZnS and ZnO nanocrystals................................112 Conclusions......................................................................................................... 116 References........................................................................................................... 118 vii CHAPTER PAGE CHAPTER 6 INTENSE BROADBAND FLUORESCENCE FROM NANOCRYSTALLINE ZINC SULFIDE-SILICA AND CADMIUM SULFIDE-SILICA COMPOSITES ....................................................................................................... 121 Introduction........................................................................................................