Investigating synthesis of Cu2ZnSn(Se1-x,Sx)4 for values of 0≤x≤1 by S for Se substitution and direct sulphidisation of metallic precursors

Thin layers of Cu2ZnSn(Se1-x,Sx)4 were produced by selenisation and subsequent sulphur substitution of DC sputter-deposited metallic CZT precursors on soda-lime glass. Values of x=(0, 0.07, 0.12, 0.17, 0.28, 1) were measured by EDS. Samples were characterised optically and analysed using the Kubelka-Munk function, and found to have 0.96eV ≤Eg≤ 1.47eV, varying approximately linearly with x. Samples underwent X-ray diffraction characterisation and substituted samples were found to comprise of multiple phase kesterite material with different levels of S substitution, averaging to the values obtained by EDS. The spectra were found to conform to Vegard's law, as peak location shifted linearly between x=0 and x=1. Binary phases are suspected to exist, because of some unusual behaviour at the location of the (200) peak. Lattice parameters for all phases were calculated and found to vary linearly between (a=b=5.692, c=11.338) for x=0 and (a=b= 5.393, c= 10.863) for x=1, which are in excellent agreement with previously published figures

Characterisation of Thin Films CuIn1-xAlxSe2 Prepared by Selenisation of Magnetron Sputtered Metallic Precursors

Thin films of CuIn1-xAlxSe2 have been produced by the selenisation of magnetron sputtered Cu/In/Al precursor layers using elemental selenium and the chemical and physical properties of the layers have been determined for different conditions of synthesis. For optimum conditions of synthesis it was found possible to produce single phase films with the chalcopyrite structure. These films were pinhole free, had good adhesion and were conformal to the substrate. The films had uniform depth profiles as determined using the MiniSIMS. The layers were highly photoactive, indicating that they have the potential to be used to fabricate thin film photovoltaic solar cell devices

Radio Observations of Super Star Clusters in Dwarf Starburst Galaxies

We present new radio continuum observations of two dwarf starburst galaxies, NGC3125 and NGC5408, with observations at 4.80GHz (6cm) and 8.64GHz (3cm), taken with the Australia Telescope Compact Array (ATCA). Both galaxies show a complex radio morphology with several emission regions, mostly coincident with massive young star clusters. The radio spectral indices of these regions are negative (with alpha ~ -0.5 - -0.7), indicating that the radio emission is dominated by synchrotron emission associated with supernova activity from the starburst. One emission region in NGC5408 has a flatter index (alpha ~ -0.1) indicative of optically thin free-free emission, which could indicate it is a younger cluster. Consequently, in these galaxies we do not see regions with the characteristic positive spectral index indicative of optically obscured star-formation regions, as seen in other dwarf starbursts such as Hen 2-10.Comment: Accepted for publication in MNRA

Mapping the solid-state properties of crystalline lysozyme during pharmaceutical unit-operations

Bulk crystallisation of protein therapeutic molecules towards their controlled drug delivery is of interest to the biopharmaceutical industry. The complexity of biotherapeutic molecules is likely to lead to complex material properties of crystals in the solid state and to complex transitions. This complexity is explored using batch crystallised lysozyme as a model. The effects of drying and milling on the solid-state transformations of lysozyme crystals were monitored using differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), FT-Raman, and enzymatic assay. XRPD was used to characterise crystallinity and these data supported those of crystalline lysozyme which gave a distinctive DSC thermogram. The apparent denaturation temperature (Tm) of the amorphous lysozyme was ∼201 °C, while the Tm of the crystalline form was ∼187 °C. Raman spectra supported a more α-helix rich structure of crystalline lysozyme. This structure is consistent with reduced cooperative unit sizes compared to the amorphous lysozyme and is consistent with a reduction in the Tm of the crystalline form. Evidence was obtained that milling also induced denaturation in the solid-state, with the denatured lysozyme showing no thermal transition. The denaturation of the crystalline lysozyme occurred mainly through its amorphous form. Interestingly, the mechanical denaturation of lysozyme did not affect its biological activity on dissolution. Lysozyme crystals on drying did not become amorphous, while milling-time played a crucial role in the crystalline-amorphous-denatured transformations of lysozyme crystals. DSC is shown to be a key tool to monitor quantitatively these transformations

Poems concerning the Stanley family (Earls of Derby) 1485-1520

This thesis is an edition of four poems (Lady Bessiye, Bosworth Feilde, Scotish Feilde, and Flodden Feilde) which were written in celebration of the military successes of the family of Stanley, Lords Stanley and Earls of Derby, at the battles of Bosworth (1485) and Flodden (1513). The introduction discusses the manuscripts and editions, the conditions for which the poems were composed, the style of the poems, and their contributions to the history of the period. The poems are newly edited, and the commentaries attempt, as well as elucidating the meanings of obscure lines, to identify the people and places which would have been of interest to the Stanley family and friends

Investigations of ternary Cu3SbS3 thin films as absorber in photovoltaic devices

Magnetron sputtered Cu-Sb metallic precursors were sulphidised on glass and molybdenum/glass substrates at 6 different temperatures. Two techniques were adopted for the elemental sulphidisation process. Precursors sulphidised using evaporated elemental sulphur were successfully converted into Cu3SbS3 solar absorber layers on molybdenum substrates. The as-sulphidised films exhibited p-type conductivity were produced in the limited response when analysed using a Eu+ electrolyte arrangement to measure the photocurrent. The films exhibited an energy bandgap value of 1.84eV

Control of grain size in sublimation-grown CdTe, and the improvement in performance of devices with systematically increased grain size

A method to control the grain size of CdTe thin films deposited by close space sublimation using chamber pressure is demonstrated. Grain diameter is shown to increase in the pressure range 2–200 Torr, following the linear relationship D (?m)=0.027×P (Torr)+0.90. A mechanism is proposed to explain the dominance of the 111 preferred orientation in the small-grained, but not the large-grained films. For a series of CdTe/CdS solar cells in which the only variable was grain size, the performance parameters were seen to increase from 0.54% (0.94 ?m grains) up to a plateau of 11.3% (?3.6 ?m grains). This corresponds to the point at which the series resistance is no longer dominated by grain boundaries, but by the contacts