Synthesis and characterisation of Zn2NF

Zhu, Yu (2018) Synthesis and characterisation of Zn2NF. MSc(R) thesis, University of Glasgow.

Abstract

This work concerned the synthesis and characterisation of zinc nitride fluoride and an array of N, F co-doped ZnO materials. The synthesis of bulk Zn2NF requires a high purity zinc nitride (Zn3N2) precursor, which is impossible to obtain commercially. For this reason, an important point of the project involved the synthesis of Zn3N2 by thermal ammonolysis of pure zinc powder. Compared to methods reported in literature, the synthetic reaction was improved by acting principally on the cooling phase of the reaction. Rapid quenching dramatically reduced the amount of impurities (mainly ZnO). The origin of the oxide impurities in Zn3N2 was also investigated and as point of this study. The interactions of molten zinc with ammonia were examined was synthesis parameters.
Zn2NF was successfully synthesised, although no evidence of the previously reported low-temperature orthorhombic phase was observed. The pure material was obtained only when high-purity, oxygen-free atmospheres were used in the preparation. Despite the decrease in band gap compared to ZnO, the potential photocatalytic properties and performance of the material are negatively affected by oxidative reactions occurring in the presence of water, leading to the gradual formation of ZnO from Zn2NF.
Doping procedures successfully reduced the band gap of ZnO, demonstrating that insertion of fluorine could be achieved more readily compared to nitrogen. Among the different procedures, ammonolysis of ZnF2 or ZnO in combination with NH4F led to the simultaneous inclusion of the two non-metals, in some cases altering the original crystal structure of ZnO.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: Zinc nitride, Zinc nitride fluoride, PXRD, Band gap.
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering > School of Chemistry
• Supervisor's Name: Gregory, Prof. Duncan
• Date of Award: 2018
• Depositing User: Mr Yu Zhu
• Unique ID: glathesis:2018-8931
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 17 Apr 2018 12:51
• Last Modified: 11 May 2018 15:50
• URI: https://theses.gla.ac.uk/id/eprint/8931