The synthesis and characterisation of metal oxide thin films

This thesis details the use of chemical vapour deposition to deposit transparent conducting oxide (TCO) thin films for potential use in a wide range of applications ranging from electrodes in photovoltaic devices to low-ε-coatings in architectural glazing. TCO materials exhibit optical transparency along with electrical conductivity. The nature of electrical conductivity arises from either excess electrons in the conduction band or holes in the valence band. FTO thin films were deposited by use of an aerosol delivery system from methanolic solutions of monobutyltin trichloride. The deposition temperature was varied from 350-550 °C. The as-synthesised films displayed enhanced functional properties compared to commercial standards in terms of film microstructure i.e. pyramidal particle microstructure ideal for enhanced light scattering required for amorphous based silicon solar cells and also sheet resistances comparable to commercial standards. The natural progression from tin dioxide films was to explore zinc oxide thin films with respect to their opto-electronic properties. Highly conductive and transparent ZnO films were synthesized by the reaction of diethyl zinc (in toluene) with methanol by dual source aerosol assisted chemical vapour deposition. The scope of this thesis then moves away from TCO materials and concentrates on microporous oxide films produced by combining chemical vapour deposition (CVD) and hydrothermal methods. Dense, adhesive zeolitic films were synthesised from this method by using a CVD process to deposit a dense amorphous silica or titanium doped silica which was then converted to a crystalline nanoporous zeolite by a hydrothermal process using an organic structure directing agent. To demonstrate the capability of the method, silicalite (S-1) and titanium silicalite (TS-1) zeolites were prepared. In order to assess the generality of this method metal organic framework films were also synthesised by reacting zinc oxide films, deposited by chemical vapour deposition (CVD), with the appropriate linker in a conventional solvothermal process

A novel route to Pt-Bi2O3 composite thin films and their application in photo-reduction of water

A novel homoleptic bismuth(III) β-diketonate (dibenzoylmethane – dbm) complex [Bi(dbm)3]2 has been used as a precursor to thin films of crystalline β-Bi2O3, and hexachloroplatinic acid (H2PtCl6·6H2O) has been demonstrated as a suitable precursor for deposition of platinum nanoparticles, both deposited via aerosol-assisted chemical vapour deposition (AACVD). Thin films of Pt–Bi2O3 were co-deposited from a mixture of [Bi(dbm)3]2 and H2PtCl6·6H2O; the introduction of Pt particles into β-Bi2O3 causes hydrogen to be evolved during photolysis of water over the composite material, a property not found for Pt particles or β-Bi2O3 alone

Ogbu and the debate on educational achievement: an exploration of the links between education, migration, identity and belonging

This paper looks at some of the issues raised by Ogbu’s work in relation to the education of different minority ethnic groups. Ogbu poses questions such as the value attached to education, its links to the future and its measurable outcomes in terms of ‘success’ as experienced by black participants. The desire for better life chances leads families to consider migration to a new country or resettlement within the same country, thus making migration both a local and a global phenomenon. As an example, attention is drawn to the situation facing South Asian children and their families in the UK. In terms of ethnicity and belonging, the wider question that is significant for many countries in the West after ‘Nine-Eleven’ is the education of Muslim children. A consideration of this current situation throws Ogbu’s identification of ‘autonomous minority’ into question. It is argued that a greater understanding of diverse needs has to be accompanied by a concerted effort to confront racism and intolerance in schools and in society, thus enabling all communities to make a useful contribution and to avoid the ‘risk’ of failure and disenchantment

Single Step Solution Processed GaAs Thin Films from GaMe3 and tBuAsH2 under Ambient Pressure

This article reports on the possibility of low-cost GaAs formed under ambient pressure via a single step solution processed route from only readily available precursors, tBuAsH2 and GaMe3. The thin films of GaAs on glass substrates were found to have good crystallinity with crystallites as large as 150 nm and low contamination with experimental results matching well with theoretical density of states calculations. These results open up a route to efficient and cost-effective scale up of GaAs thin films with high material properties for widespread industrial use. Confirmation of film quality was determined using XRD, Raman, EDX mapping, SEM, HRTEM, XPS, and SIMS

Diasporic virginities: social representations of virginity and identity formation amongst British arab muslim women

This study compares how practising and non-practising British Arab Muslim women position themselves in relation to representations of virginity. Overall, in our qualitative study, we found that representations of culture and religion influenced social practices and social beliefs in different ways: non-practising Muslim women felt bound by culture to remain virgins, while practising Muslim women saw it as a religious obligation but were still governed by culture regarding the consequences of engaging in premarital sex. Interestingly, some practising Muslim participants used Mut’a (a form of temporary ‘marriage’) to justify premarital sex. This, however, did not diminish the importance of virginity in their understanding and identification as Arab women. In fact, this study found that virginity, for the British Arabs interviewed, embodied a sense of ‘Arabness’ in British society. Positioning themselves as virgins went beyond simply honour; it was a significant cultural symbol that secured their sense of cultural identity. In fact this cultural identity was often so powerful that it overrode their Islamic identities, prescribing their behaviour even if religion was seen as more ‘forgiving’

Awareness and understanding of dementia in South Asians: A synthesis of qualitative evidence

Hossain, M., Crossland, J., Stores, R., Dewey, A., & Hakak, Y. (2020). Awareness and understanding of dementia in South Asians: A synthesis of qualitative evidence. Dementia, 19(5), 1441–1473. Copyright © [2020] (The Author) DOI: https://doi.org/10.1177%2F147130121880064

Modular design of SPIRO-OMeTAD analogues as hole transport materials in solar cells

We predict the ionisation potentials of the hole-conducting material SPIRO-OMeTAD and twelve methoxy isomers and polymethoxy derivatives. Based on electronic and economic factors, we identify the optimal compounds for application as p-type hole-selective contacts in hybrid halide perovskite solar cells

Multifunctional P-Doped TiO 2

Multifunctional P-doped TiO2 thin films were synthesized by atmospheric pressure chemical vapor deposition (APCVD). This is the first example of P-doped TiO2 films with both P5+ and P3– states, with the relative proportion being determined by synthesis conditions. This technique to control the oxidation state of the impurities presents a new approach to achieve films with both self-cleaning and TCO properties. The origin of electrical conductivity in these materials was correlated to the incorporation of P5+ species, as suggested by Hall Effect probe measurements. The photocatalytic performance of the films was investigated using the model organic pollutant, stearic acid, with films containing predominately P3– states found to be vastly inferior photocatalysts compared to undoped TiO2 films. Transient absorption spectroscopy studies also showed that charge carrier concentrations increased by several orders of magnitude in films containing P5+ species only, whereas photogenerated carrier lifetimes—and thus photocatalytic activity—were severely reduced upon incorporation of P3– species. The results presented here provide important insights on the influence of dopant nature and location within a semiconductor structure. These new P-doped TiO2 films are a breakthrough in the development of multifunctional advanced materials with tuned properties for a wide range of applications