5d Transition Metal Oxyhydrides

Transition metal oxyhydrides are uncommon materials that contain both oxide and hydride ions in the anion lattice. Due to the contrasting features of the two ions, they exhibit a range of interesting properties that would not be accessible to metal oxides. The lower charge of the hydride ion relative to oxide ions stabilises transition metals with lower oxidation states than are typically observed for metal oxides, whilst the lower electronegativity and higher polarizability of hydride ions relative to oxide ions can result in increased covalency and stronger magnetic interactions. In addition, the symmetry of hydride ions is different from oxide ions, which can dramatically affect the orbital connectivity within the material and lead to materials with reduced dimensionality in their electronic structure. As such, transition metal oxyhydrides often have fundamentally different chemical and physical properties to the corresponding oxides. As a result of their unusual chemical behaviour, oxyhydrides could become an important class of functional material with potential applications in hydrogen fuel cells or as catalysts in ammonia synthesis.
Due to the strongly reducing nature of the hydride ion, transition metal oxyhydrides are generally thermodynamically unstable with respect to the elemental metal and water, so preparing these materials through conventional high temperature ceramic synthesis methods is unfeasible. As such, soft chemistry methods are required to synthesise transition metal oxyhydrides as metastable phases, whereby hydride ions are inserted directly into a parent crystal structure at low temperature. Recently, these methods have been used to synthesise a number of oxyhydrides containing 3d and 4d transition metals. Many of these were found to exhibit novel electronic and magnetic properties, and they often adopt structures containing MH2 or MO2 sheets, which are analogous to the CuO2 sheets found in cuprate superconductors.
This project aims to prepare the first oxyhydrides that contain 5d transition metals. In contrast to previously prepared transition metal oxyhydrides, the strong spin-orbit coupling and wide bands associated with 5d metals are expected to yield materials with qualitatively different chemical and physical properties to lighter transition metal analogues, which could lead to desirable features, such as superconductivity or magnetoresistivity. In addition, due to the delicate balance of interactions that localise and delocalise electrons in 5d transition metal compounds, small alterations in the crystal structure can lead to dramatic changes in the electronic and magnetic properties of the compound, thereby suggesting that a rich variety of physical behaviours are accessible in these materials. As such, these compounds are likely to provide fertile ground for the discovery of new materials with novel electronic and magnetic properties.
This project falls within the EPSRC Functional Ceramics and Inorganics research area.

The primary impact of the OxICFM CDT will be the highly-trained world-class scientists that it delivers. This impact will encompass both the short term (during their doctoral studies), the medium term (subsequent employment) and ultimately the longer timescale defined by their future careers and consequent impact on science, engineering and policy in the UK.

The impact of OxICFM students during their doctoral studies will be measured by the culture change in graduate training that the Centre brings about - in working at the interface between inorganic synthesis and manufacturing, and fostering cross-sector industry/academia working practices. By embedding not only from larger companies, but also SMEs, we have developed a training regime that has broader relevance across the sector, and the potential for building bridges by fostering new collaborations spanning enormous diversity in scientific focus and scale. Moreover, at a broader level, OxICFM offers to play a unique role as a major focus (and advocate) for manufacturing engagement with academic inorganic synthetic science in the UK.

From a scientific perspective, OxICFM will be uniquely able to offer a broad training programme incorporating innovative and challenging collaborative projects spanning all aspects of fundamental and applied inorganic synthesis, both molecular and materials based (40+ faculty). These will address key challenges in areas such as energy provision/storage, catalysis, and resource provision/renewal necessary to enhance the capability and durability of UK plc in the medium term. To give some idea of perspective, the output from previous CDTs in Oxford's MPLS Division include two start-up companies and in excess of 30 patents.

It is not only in the industrial and scientific realms that students will have impact during their timeframe of their doctorate. Part of the training programme will be in public engagement: team-based challenges in resource development/training and outreach exercises/implementation will form part of the annual summer school. These in turn will constitute a key part of the impact derived from the CDT by its engagement with the public - both face-to-face and through electronic/web-based media. As the centre matures, our aspiration is that our students - from diverse backgrounds - will act as ambassadors for the programme and promote even higher levels of inclusion from all parts of society.

For our partners, and businesses both large and small in the manufacturing sector, it will be our students who are considered the ultimate output of the OxICFM CDT. Our programme has been shaped by the need of such companies (frequently expressed in preliminary discussions) to recruit doctoral graduates who can apply themselves to a broad spectrum of multi-disciplinary challenges in manufacturing-related synthesis. OxICFM's cohort-based training programme integrates significant industry-led training components and has been designed to deliver a much broader skill set than standard PhD schemes. The current lack of CDT training at the interface of inorganic chemistry and manufacturing (and the relevance of inorganic molecules/materials to numerous industrial sectors) heightens the need for - and the potential impact of - the OxICFM CDT. Our students will represent a tangible and valuable asset to meet the long-term skills demand for scientists to develop new materials and nanotechnology identified in the UK Government's 2013 Foresight report.

In the longer term, the broad and relevant training delivered by OxICFM, and the uniquely wide perspective of the manufacturing sector it will deliver, will allow our graduates to obtain (and thrive in) positions of significant responsibility in industry and in research facilities/institutes. Ultimately we believe that many will go on to be future research leaders, driving innovation and changing research culture, and thereby making a lasting contribution to the UK economy.