We present the first Southern-Hemisphere all-sky imager and radio-transient monitoring system implemented on two prototype stations of the low-frequency component of the Square Kilometre Array (SKA-Low). Since its deployment, the system has been used for real-time monitoring of the recorded commissioning data. Additionally, a transient searching algorithm has been executed on the resulting all-sky images. It uses a difference imaging technique to enable identification of a wide variety of transient classes, ranging from human-made radio-frequency interference to genuine astrophysical events. Observations at the frequency 159.375 MHz and higher in a single coarse channel ( $\approx$ 0.926 MHz) were made with 2 s time resolution, and multiple nights were analysed generating thousands of images. Despite having modest sensitivity ( $\sim$ few Jy beam–1), using a single coarse channel and 2-s imaging, the system was able to detect multiple bright transients from PSR B0950+08, proving that it can be used to detect bright transients of an astrophysical origin. The unusual, extreme activity of the pulsar PSR B0950+08 (maximum flux density $\sim$ 155 Jy beam–1) was initially detected in a ‘blind’ search in the 2020 April 10/11 data and later assigned to this specific pulsar. The limitations of our data, however, prevent us from making firm conclusions of the effect being due to a combination of refractive and diffractive scintillation or intrinsic emission mechanisms. The system can routinely collect data over many days without interruptions; the large amount of recorded data at 159.375 and 229.6875 MHz allowed us to determine a preliminary transient surface density upper limit of $1.32 \times 10^{-9} \text{deg}^{-2}$ for a timescale and limiting flux density of 2 s and 42 Jy, respectively. In the future, we plan to extend the observing bandwidth to tens of MHz and improve time resolution to tens of milliseconds in order to increase the sensitivity and enable detections of fast radio bursts below 300 MHz.

An investigation into the relative stabilities and equations of state of stoichiometric FeS was conducted using first-principles pseudopotential calculations. These calculations were based on density functional theory and performed using ultrasoft Vanderbilt pseudopotentials within the generalized gradient approximation. We have identified four stable polymorphs of FeS along the 0 K isotherm as a function of pressure: troilite, an orthorhombic MnP-type structure, a monoclinic structure, and a CsCl-type structure. The calculated internal energy as a function of volume for each polymorph was fitted to 4th order logarithmic and 3rd order Birch-Murnaghan equations of state, yielding values for the bulk modulus, K, and its first and second derivatives with respect to pressure, K′ and K″. These equations of state may be used to characterize models of planetary cores.

In order to be able to use the nature and scale of the exsolution microstructures developed in titanomagnetites as quantitative indicators of thermal history, it is necessary to have available accurate diffusion data for the system. Diffusion data for pure magnetite and Ti-poor titanomagnetites are available, but no data for diffusion in the centre of the solid-solution series exist. In order to obtain values for the activation energy (ΔE) and the pre-exponential factor (D0) for the interdiffusion of Fe and Ti in ulvöspinel-rich titanomagnetites, the natural microstructures developed in titanomagnetites from the Taberg intrusion, Sweden, were homogenized over a range of temperatures from 490 to 730 °C. From the model describing homogenization, values of 49.8 kcal mole−1 and 2.38 × 10−3 cm2 s−1 were calculated for ΔE and D0 respectively. Although the results obtained from these homogenization experiments are slightly less accurate than those which could be obtained by more conventional methods, the homogenization technique has several advantages which outweigh this drawback, namely the ease with which the experiment can be performed and the fact that the diffusion data can be obtained at significantly lower temperatures than is usually possible with more conventional methods.

The structure and elastic properties of MgSiO3, a major mantle-forming phase, have been simulated using computer models which predict the minimum energy structure by using interatomic pair potentials to describe the net forces acting between the atoms. Four such interatomic potentials were developed in this study, and are compared with potential N1 of Miyamoto and Takeda (1984). The most successful potential (W3) was derived by fitting the short range potential parameters to both the experimentally obtained structural and elastic properties of MgSiO3 perovskite. The relative stabilities of some of the possible perovskite polymorphs, the orthorhombic, cubic, and tetragonal phases and hexagonal polytypes, were evaluated at 0 K and between 1 bar and 2 Mbar. The orthorhombic phase is found to be stable at all but the highest pressures, where the cubic phase may be stable. The temperature of the ortho-rhombic to cubic transition may decrease with increasing pressure. The energy of a stacking fault on (110) in the cubic phase was estimated using the ANNNI model and found to be about 1.95 J m−2 using potential W3. The distance of separation of partial dislocations of this type is predicted to increase with increasing pressure from 8.4 Å at 1 bar to 9.2 Å at 1 Mbar.

We summarize the main ideas used to determine the thermodynamic properties of pure systems and binary alloys from first principles calculations. These are based on the ab initio calculations of free energies. As an application we present the study of iron and iron alloys under Earth,s core conditions. In particular, we report the whole melting curve of iron under these conditions, and we put constraints on the composition of the core. We found that iron melts at 6350士600 K at the pressure corresponding to the boundary between the solid inner core and the liquid outer core (ICB). We show that the core could not have been formed from a binary mixture of Fe with S, Si or O and we propose a ternary or quaternary mixture with 8—10% of S/Si in both liquid and solid and an additional ~8% of oxygen in the liquid. Based on this proposed composition we calculate the shift of melting temperature with respect to the melting temperature of pure Fe of ~—700 K, so that our best estimate for the temperature of the Earth's core at ICB is 5650±600 K.

The commissioning and operation of apparatus for neutron diffraction at simultaneous high temperatures and pressures is reported. The basic design is based on the Paris-Edinburgh cell using opposed anvils, with internal heating. Temperature is measured using neutron radiography. The apparatus has been shown in both on-line and off-line tests to operate to a pressure of 7 GPa and temperature of 1700°C. The apparatus has been used in a neutron diffraction study of the crystal structure of deuterated brucite, and results for 520°C and 5.15 GPa are presented. The diffraction data that can be obtained from the apparatus are of comparable quality to previous high-pressure studies at ambient temperatures, and are clearly good enough for Rietveld refinement analysis to give structural data of reasonable quality.

An investigation of the relative stabilities and equations of state of possible Fe3S polymorphs was conducted using first-principles pseudopotential calculations. These calculations were based on density functional theory and performed using ultrasoft Vanderbilt pseudopotentials within the generalized gradient approximation. In accord with experiment, we found that the tetragonal Fe3P-type polymorph is the only stable phase along the 0 K isotherm as a function of pressure. Fe3S exhibits permanent magnetism at ambient conditions (Fei et al., 2000), but magnetism is suppressed by pressure and temperature, and therefore non-magnetic data are appropriate ones to use for modelling planetary interiors. For this reason, and because the Fe3P-type polymorph of Fe3S contains 32 atoms per unit cell it was impractical to incorporate magnetic properties into the simulations of this phase, we studied the behaviour of the non-magnetic phase. We obtained values of 250 GPa for the bulk modulus, K0, and 4.61 for its first derivative withrespect to pressure, K0′, by fitting a 3rd order Birch-Murnaghan equation of state to the calculated internal energy as a function of volume for the non-magnetic Fe3P-type Fe3S. This suggests that a pressure far greater than that expected in the Martian interior would be needed to achieve a density comparable to that of the Martian core. We therefore conclude that it is unlikely that the core of Mars contains significant amounts of solid Fe3S.

Chrome spinels from seams in the Rhum layered intrusion, Inner Hebrides, generally contain very fine platelets of exsolved phases. Despite the low bulk Ti content (< 1%) of the spinel grains, analytical electron microscopy shows these platelets to be highly enriched in titanium. Electron diffraction indicates the presence of platelets of two different phases, one a magnesian ilmenite, the other a defect spinel intermediate phase. The platelets are the result of oxidation of the spinel at moderate (c. 600 °C) temperatures and their distribution suggests that oxygen fugacity gradients existed across some of the seams.

The procedure for deriving interatomic potentials for molecular ionic materials, using empirical fitting procedures, is described. Potentials are obtained for carbonates, phosphates and perchlorates, and used to calculate crystal and lattice properties which are compared with available experimental data.

Svetlozarite, previously described as a new member of the mordenite group of zeolites, is reinterpreted as a multiply twinned and highly faulted dachiardite. X-ray diffraction study and transmission electron microscopy revealed (001) twins and (100) stacking faults. The former are attributed at least mainly to the insertion of a b glide plane between dachiardite sheets at each twin interface, which preserves the 5-ring linkages between the sheets. The latter are associated with loss of the C face-centring relation, and are attributed to replacement of shared 5-rings by linked 4-rings in the dachiardite sheets. Further study is needed to determine whether the structural faults in the dachiardite structures are chemically controlled.