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Hydrated vanadium(III) phosphate, K3V3(PO4)4·H2O, has been synthesized by a facile aqueous hydrothermal reaction. The crystal structure of the compound is determined using X-ray diffraction (XRD) analysis aided by density functional theory (DFT) computational investigation. The structure contains layers of corner-sharing VO6 octahedra connected by corner and edge-sharing PO4 tetrahedra with a hydrated K+ ion interlayer. The unit cell is assigned to the orthorhombic system (space group Pnna) with a = 10.7161(4) Å, b = 20.8498(10) Å, and c = 6.5316(2) Å. Earlier studies of this material report a K3V2(PO4)3 stoichiometry with a NASICON structure (space group R3¯ c). Previously reported XRD and electrochemical data on K3V2(PO4)3 are critically evaluated and we suggest that they display mixed phase compositions of K3V3(PO4)4·H2O and known electrochemically active phases KVP2O7 and K3V(PO4)2. In the present study, the synthesis conditions, structural parameters, and electrochemical properties (vs K/K+) of K3V3(PO4)4·H2O are clarified along with further physical characterization by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray fluorescence (XRF), Raman spectroscopy, Fourier transform infrared (FT-IR), and thermogravimetric analysis (TGA).

THz/Far Infrared synchrotron absorption experiments on pure and doped MgB2 samples show that the absorption spectral weight at low wavenumber (i.e., <110 cm−1) evolves as the temperature is reduced to 10 K. Distinct spectral peak intensities increase as the temperature of MgB2 and doped MgB2 approaches, and then crosses, the superconducting transition temperature. These experimental data suggest a strong link to superconductivity induced by subtle shifts in structural symmetry. Significant increases in absorption are observed at frequencies that correspond to the superconducting gaps for doped and pure MgB2, and at fractions of these frequency (or energy) values. This low wavenumber spectral transition is consistent with the notion that superlattice frequencies contribute to the optic modes of the MgB2 phonon dispersion and are critical to the superconducting transition for this structure. Key integer ratios are identified in real and reciprocal spaces that link bonding character, Fermi vectors and Fermi surfaces as well as phonon properties with geometric parameters and specific superlattice symmetries for MgB2. Similarly consistent spectral data at low wavenumber are also obtained for carbon doped Mg11B2. Density Functional Theory calculations of superlattice phonon dispersions result in folded mode frequencies that match these observed low wavenumber experiments. These results show that symmetry reductions, largely electronic in character although coupled to vibrations, occur with change in temperature and imply strong links to superconductivity mechanisms.

The breadth and depth of applications for two-dimensional (2D) materials which, by their nature, are nanoscale and layer structured with a high surface to volume ratio, are extensive and rapidly transforming the field of gas sensing. Facile preparation methods, as well as novel electronic and surface properties that enable functionalisation, provide high sensitivity for gases commonly encountered in natural and industrial environments. Gas sensors that are operational at room temperature offer low power demand and thermal safety during analysis. This review focuses on room-temperature gas sensing performance of conductometric devices employing 2D hybrid nanomaterials including layered transition metal dichalcogenides (TMDs) and graphene materials. The effect of hybridisation of 2D nanomaterials on gas sensing performance and their sensing mechanisms are studied. Hybrid forms of 2D materials occur by the addition of metals, or polymers to surface sites, or by combining two or more different materials (i.e. nanocomposites) or by developing a heterojunction layer, which lead to enhanced collective performance. Gas sensing mechanisms depend on the type and format of 2D material but fundamentally involve gas adsorption on an active surface with a resultant change in the resistive property of the material.

Distinctive Cr-MOF@Da composites have been constructed using chromium-based metal-organic frameworks (MOFs) and diatomite (Da). The new materials have hierarchical pore structures containing micropores, mesopores and macropores. We have synthesized various morphologies of the MOF compound Cr-MIL-101 to combine with Da in a one-pot reaction step. These distinctive hierarchical pore networks within Cr-MIL-101@Da enable exceptional adsorptive performance for a range of molecules, including hydrogen (H2), carbon dioxide (CO2) and water (H2O) vapor. Selectivity for H2 or CO2 can be moderated by the morphology and composition of the Cr-MIL-101 included in the Cr-MOF@Da composite. The encapsulation and growth of Cr-MIL-101 within and on Da have resulted in excellent water retention as well as high thermal and hydrolytic stability. In some cases, Cr-MIL-101@Da composite materials have demonstrated increased thermal stability compared with that of Cr-MIL-101; for example, decomposition temperatures >340 °C can be achieved. Furthermore, these Cr-MIL-101@Da composites retain structural and morphological integrity after 60 cycles of repeated hydration/dehydration, and after storage for more than one year. These characteristics are difficult to achieve with many MOF materials, and thus suggest that MOF–mineral composites show high potential for practical gas storage and water vapor capture.

A suite of density functional theory (DFT) approaches that provide accurate and reliable superconductivity parameters without post-calculation corrections is presented. The sensitivity of phonon dispersion (PD) outputs to slight variations in calculation and external parameters enables identification of the most electron-coupled phonon mode(s). These mode(s) are directly linked, in a range of superconductors, to specific band structure characteristics and to the response of electrons to deformation potentials. These approaches are applied successfully to MgB2 under a wide range of variable external conditions, including isotopic state, metal substitutions, pressure, and temperature. This approach has also been extended to other chemical systems with significantly different composition and crystal symmetry, such as YB6, H3S under pressure, B-doped diamond, B-doped silicon, and A15 compounds, to name a few. The effectiveness of these approaches that link both PDs and electronic band structures (EBSs) is largely dependent on reliable and accurate DFT results at the meV range that resolve Fermi surface (FS) detail in close reciprocal space proximity. Such a level of meV resolution is possible only by using extremely fine k-grids and large cutoff radii, much smaller and larger, respectively, to what has typically been used in DFT calculations reported in the literature.

We have successfully developed poly(vinyl pyrrolidone) (PVP) and PVP/zeolite composite-coated nanomechanical Membrane-type Surface stress Sensor (MSS) for humidity and volatile organic compounds (VOCs) sensing. The VOCs include toluene, acetone, ethanol, methanol, hexane and isopropanol. At room temperature (RT), the PVP-coated MSS shows a highest response of 58.44 mV to humidity and the PVP/zeolite composite-coated MSS exhibits a highest response of 28.10 mV to isopropanol. In contrast, very weak response to hexane around 1 mV was observed for both PVP and PVP/ZSM5-coated MSS. The experimental results confirm potential use of these sensors for VOC and humidity sensing at RT.

Potassium-rich Zeolite N, with the general formula K12Al10Si10O40Cl2.nH2O, is orthorhombic with space group I222 in the EDI framework group, commonly known as a fibrous zeolite. The synthesis of zeolite N is relatively simple and can be undertaken in a typical chemistry laboratory and has been developed for use at commercial scale. Molecular dynamic simulation results showed that zeolite N has a high monovalent cation exchange capacity and a high uptake selectivity toward ammonium ions in aqueous solution that is consistent with experimental data. In this study we simulated the penetration and exchange of univalent cations (NH4+, Li+, Na+, K+, Rb+ and Cs+) into zeolite N from surfaces with different shape and entrance pore size.

Strong correlations between phonon energies and superconducting transition temperatures can be extracted from phonon dispersion calculations using density functional theory for a range of superconducting materials. These correlations are robust and consistent with experimental data for key external conditions including isotope effects, elemental substitutions and pressure variations. Changes in the electronic band structure also correlate with transitions to/from superconductivity but, in general, are less sensitive and less obvious than phonon behaviour. A computational approach that considers both phonons and electrons and the presence or absence of a phonon anomaly works well for conventional superconducting materials with hexagonal, cubic or tetragonal symmetries. Superconductivity in these compounds often involves symmetry reduction in an original non-superconducting parent compound induced, for instance, by substitution or by a dynamic reduction in symmetry shown in electron density distributions and Raman spectra. Such symmetry reduction is effectively modelled with super-lattice constructs which link Raman spectra with key superconducting parameters.

Density Functional Theory (DFT) of electronic structure is widely used to simulate many structures and systems in chemistry and physics. In many cases, these simulations have been highly successful at explaining IR spectra, binding sites and activation energies while there are also some critical failures due to delocalization and correlation errors of commonly used functionals. In some cases, such as the prediction of superconducting properties using band structures, experimental data more commonly inform post-facto estimates of physical properties. In this work, we demonstrate the efficacy of DFT in modern computational programs for prediction of the superconducting transition temperature (Tc) for diboride structures.

The field of superconductivity is rich in history – more than 100 years – yet still at the forefront of scientific and technological revolutions that have not only led to new markets but also continue to disrupt existing markets. Superconducting science, technology and engineering is poised to transform completely the global energy sector over the next twenty to thirty years through lower cost and more efficient generation, distribution and storage of electrons. These benefits from superconductivity will accrue in different applications or market segments depending on the relative performance (e.g. current density, magnetic field strength, materials properties) at specific operating temperatures which can range from ~20 K to ~ 100 K at the present time. Superconductivity invokes two key physical attributes that are used in a wide range of applications. These attributes are zero electrical resistance for transfer of electrons and the expulsion of magnetic flux fields in a solid when cooled below a certain temperature, Tc, called the critical temperature. These attributes currently apply to 32 classes of materials or at least 500 specific compounds that meet these criteria. The past thirty years of research, development and demonstration has resulted in a plethora of new materials identified as superconductors – more than twice the number identified in the previous 60 years – with clear implications that additional new materials will continue to be identified. The pace of enquiry will continue unabated until a superconductor with a Tc > 300 K or higher is synthesised and trialled as a wire or tape. The development of new applications will then massively transform many market sectors including the maritime environment.

A predictive tool for the design of new, higher temperature superconductors requires a simple, first-principles technique, based on well-established axioms as embodied in Density Functional Theory without post-calculation corrections or increased levels of complexity. We show that anomalies in the calculated phonon dispersions of compounds with AlB2-type structures are good descriptors of their superconducting transition temperatures. This ab initio methodology has proven robust for descriptions of: the superconductivity of MgB2 and other related AlB2-type structures [1], the different isotopic forms of MgB2 [2], a series of substituted MgB2 compositions with Al [3] and transition metals [4], the pressure dependence of the superconductivity of MgB2 [5] and various temperature effects.

A comprehensive analysis of more than 7,000 topsoil and subsoil samples in Australia, matched with remote sensing and other data, confirms that clays are abundant, pervasive and regionally distributed across this significantly weathered continental landscape1. The predominant use of these clays within Australia is for building materials (e.g. paints, paper filler, bricks), ceramics and porcelain, horticulture and environmental remediation. Commercial use of clays in environmental remediation is as liners, geological barriers and containment walls in tailings dams, landfills, wetlands and water supply channels. Geosynthetic clay liners have widespread use in the construction/civil, mining and environmental sectors in Australia and involve forming bentonite within a flexible engineered fabric but the clay is essentially unmodified. This talk will focus on chemical modifications of clays resulting in either transformation of the source aluminosilicate or enhanced functionality due to adsorption of key compounds/elements.

The refractory forms of boron show performance parameters that are critical for future technological applications such as superconductivity, thermo-electric and high temperature conduction. In this work, we focus on AlB2-type structures – their synthesis and DFT model calculations. We synthesise MgB2 and other diborides within parameter-controlled steel reactors at relatively low temperatures (~600oC) using intermediate borohydride compounds. In addition, we use DFT calculations, and the presence of phonon anomalies, to provide insight into diborides and their superconducting properties. We use these two complementary approaches to design new compositions that are predicted to have superconducting transition temperature (Tc) values that, in some cases, exceed the value for MgB2. Similarly, the absence of a phonon anomaly in Phonon Dispersion plots implies limited or no capacity for superconductivity. Our evaluation of electron-phonon interactions using DFT models in this structure type offers the potential to target key compositions for electronic, photovoltaic and energy applications.

We have shown that novel synthesis methods combined with careful evaluation of DFT phonon calculations provides new insight into boron compounds including a capacity to predict Tc for AlB2-type superconductors.

Synthesis of metal borides is typically undertaken at high temperature using direct combinations of elemental starting materials[1]. Techniques include carbothermal reduction using elemental carbon, metals, metal oxides and B2O3[2] or reaction between metal chlorides and boron sources[3]. These reactions generally require temperatures greater than 1200oC and are not readily suitable for an industrial setting nor scalable to bulk production.

Attention has recently focussed on MgB2 superconductors (Tc~39K) which can be formed into wires with high material density and viable critical current densities (Jc)1. However, broader utilisation of this diboride and many others is likely to occur when facile synthesis for bulk applications is developed. To date, common synthesis methods include high temperature sintering of mixed elemental powders2, combustion synthesis3, mechano-chemical mixing with high temperature sintering4 and high pressure (~GPa region) with high temperature. In this work, we report on a lower temperature, moderate (<4MPa) pressure method to synthesise metal diborides.

Over the past ten years, scaled-up utilisation of a previously under-exploited zeolite, Zeolite N1, has been demonstrated for selective ion exchange of ammonium and other ions in aqueous environments. As with many zeolite syntheses, the required source material should contain predictable levels of aluminium and silicon and, for full-scale industrial applications, kaolin and/or montmorillonite serve such a purpose. Field, pilot and commercial scale trials of kaolin-derived Zeolite N have focused on applications in agriculture and water treatment as these sectors are primary producers or users of ammonium. The format for the material – as fine powders, granules or extrudates – depends on the specific application albeit each has been evaluated.

Desalination processes to remove dissolved salts from seawater or brackish water includes common industrial scale processes such as reverse osmosis, thermal processes (i.e. multi-stage flash, multiple-effect distillation) and mechanical vapour compression. These processes are very energy intensive. The Institute for Future Environments (IFE) has evaluated various alternative processes to accomplish desalination using renewable or sustainable energy sources. A new process - a solar, thermally driven distillation system . based on the principles of a solar still – has been examined. This work presents an initial evaluation of the process.

Sandy soils have low nutrient holding capacity and high water conductivity. Consequently, nutrients applied as highly soluble chemical fertilisers are prone to leaching, particularly in heavily irrigated environments such as horticultural soils and golf courses. Amorphous derivatives of kaolin with high cation exchange capacity may be loaded with desired nutrients and applied as controlledrelease fertilisers. Kaolin is an abundant mineral, which can be converted to a meso-porous amorphous derivative (KAD) using facile chemical processes. KAD is currently being used to sequester ammonium from digester effluent in sewage treatment plants in a commercial environment. This material is also known in Australia by the trade name MesoLite. The ammonium-saturated form of KAD may be applied to soils as a nitrogen fertiliser. Up to 7% N can be loaded onto KAD by contacting it with high-ammonia concentration wastewater from sewerage treatment plants. This poster paper demonstrates plant uptake of nitrogen from KAD and compares its efficiency as a fertiliser with NH4SO4. Rye grass was grown in 1kg pots in a glass-house. Nitrogen was applied at a range of rates using NH4SO4 and two KAD materials carrying 7% and 3% nitrogen, respectively. All other nutrients were applied in adequate amounts. All treatments were replicated three times. Plants were harvested after four weeks. Dry mass and N concentrations were determined by standard methods. At all N application rates, ammonium-loaded KAD produced significantly higher plant mass than for NH4SO4. The lower fertiliser effectiveness of NH4SO4 is attributed to possible loss of some N through volatilisation. Of the two KAD types, the material with lower CEC value supported slightly higher plant yields. The KAD materials did not show any adverse effect on availability of trace elements, as evidenced by lack of deficiency symptoms and plant analyses. Clearly, nitrogen loaded on to KAD in the form of ammonium is likely to be protected from

A suite of new materials, based on chemical modification of kaolins, has been successfully prepared via manipulation of the kaolin structure and subsequent intercalation by CaCl2 and MgCl2. A standard kaolinite(KGa-1)and a commercially available halloysite (New Zealand china clay) were used for this study. The kaolins are given several cycles of intercalation and deintercalation using a common intercalant such as potassium acetate. The number of cycles given depends on the type of kaolin. After this treatment, both kaolinite and halloysite hydrate show considerable broadening of the (00l) reflections which indicate extensive exfoliation of the layers. In the case of kaolinite, exfoliated layers roll to form tubes similar to proper halloysite. Kaolins modified by the above treatment readily intercalate MgCl2 and CaCl2 from saturated solutions of these salts. On intercalation with CaCl2 and MgCl2, kaolinite layers expand to 10A and 9.8A, and those of halloysite to 12.8A and 15.5A, respectively. To our knowledge, this is the first report of successful intercalation of alkaline-earth halides by kaolins.

Chemical treatments of kaolins to produce nanocrystalline or "X-ray amorphous", stable aluminosilicates with variable - but reproducible - types of micro- and meso-porosity have been developed. These materials show cation exchange capacities and surface area values significantly higher (ranging from 10x to 100x) than kaolin and show good acid resistance to pH~3.0. The combination of these properties offers strong potential for many new applications of kaolin-derived materials in large worldwide markets such as environmental remediation and catalysis. Kaolin amorphous derivative (KAD) is well-suited to removal of many toxic metals down to ppb range from acid mine drainage. Engineering development trials of the KAD manufacturing process and the utilisation of KAD in polluted waters such as acid mine drainage indicates that scale-up from bench-scale is not a barrier to market entry.

The degree of diversity or similarity detected in comets depends primarily on the lifetimes of the individual cometary nuclei at the time of analysis. It is inherent in our understanding of cometary orbital dynamics and the seminal model of comet origins that cometary evolution is the natural order of events in our Solar System. Thus, predictions of cometary behaviour in terms of bulk physical, mineralogical or chemical parameters should contain an appreciation of temporal variation(s). Previously, Rietmeijer and Mackinnon [1987] developed mineralogical bases for the chemical evolution of cometary nuclei primarily with regard to the predominantly silicate fraction of comet nuclei. We suggested that alteration of solids in cometary nuclei should be expected and that indications of likely reactants and products can be derived from judicious comparison with terrestrial diagenetic environments which include hydrocryogenic and low-temperature aqueous alterations. In a further development of this concept, Rietmeijer [1988] provides indirect evidence for the formation of sulfides and oxides in comet nuclei. Furthermore, Rietmeijer [1988] noted that timescales for hydrocryogenic and low-temperature reactions involving liquid water are probably adequate for relatively mature comets, e.g. P/comet Halley. In this paper, we will address the evolution of comet nuclei physical parameters such as solid particle grain size, porosity and density. In natural environments, chemical evolution (e.g. mineral reactions) is often accompanied by changes in physical properties. These concurrent changes are well-documented in the terrestrial geological literature, especially in studies of sediment diagenesis and we suggest that similar basic principles apply within the upper few meters of active comet nuclei. The database for prediction of comet nuclei physical parameters is, in principle, the same as used for the proposition of chemical evolution. We use detailed mineralogical studies of cho