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Title: Stoichiometric manipulation of inorganic compounds to function as near infrared absorbers
Author: Coulter, Rachel
ISNI:       0000 0004 6058 1759
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2015
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The synthesis, characterisation and testing of compounds to function as near-infrared (NIR) absorbers in a patented laser imaging process is presented. Working in conjunction with industrial partner Datalase Ltd, the project has focussed on finding materials which absorb NIR radiation for use in inks. The material is required to absorb NIR radiation from a laser and transfer it to a colour-changing pigment as heat in order to form images. The application of this process is primarily to create labels on packaging. Initially four commercial samples were analysed to provide a starting point for selecting NIR absorber candidates. Preliminary samples were synthesised and a testing procedure was established. A range of compounds were identified as potential NIR absorbers, synthesised, characterised and tested. The family of alkali metal tungsten bronzes MxWO3 was explored with various types of M and different values of x. The effect on laser imaging performance of factors such as solid state vs solvothermal synthesis routes and particle shape were investigated. As a family they were found to generally perform well. Sub-stoichiometric tungsten trioxides WO3-x were also investigated but show inferior performance as NIR absorbers compared to the tungsten bronzes. Molybdenum bronzes MxMoO3 were a natural follow-on family from the tungsten bronzes for investigation. The proved relatively difficult to synthesise in phase pure form and did not show the same level of performance as their tungsten counterparts. A phosphate tungsten bronze sample P4W12O32 had the same issues as the molybdenum bronzes – intermediate performance and difficult synthesis which is particularly undesirable for industrial applications. A number of copper phosphates and transparent conducting oxides were also studied. These samples generally had a lower level of NIR absorbance compared to the bronze samples which led to poor imaging. Throughout the project the main characterisation techniques used were powder X-ray diffraction, UV-vis-NIR spectrometry and scanning electron microscopy.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD Chemistry