Enhanced performance in transparent conducting materials at the interface of a wide band gap semiconductor and a correlated metal.

Several classes of inorganic transparent conducting coatings are available (broad band wide band gap semiconductors, noble metals, amorphous oxides and correlated metals), with peak performance depending on the layer thickness. Correlated metallic transition metal oxides have emerged as potential competitive materials for small coating thicknesses, but their peak performance remains one order of magnitude below other best in class materials. By exploiting the charge transfer at the interface between a correlated metal (SrNbO) and a wide band gap semiconductor (SrTiO), we show that pulsed laser deposition-grown SrNbO heterostructures on SrTiO outperform correlated metals by an order of magnitude.

Synthesis, Structure, and Properties of CuBiSeCl: A Chalcohalide Material with Low Thermal Conductivity.

Mixed anion halide-chalcogenide materials have recently attracted attention for a variety of applications, owing to their desirable optoelectronic properties. We report the synthesis of a previously unreported mixed-metal chalcohalide material, CuBiSeCl (), accessed through a simple, low-temperature solid-state route. The physical structure is characterized through single-crystal X-ray diffraction and reveals significant Cu displacement within the CuSeCl octahedra.

A high throughput synthetic workflow for solid state synthesis of oxides.

High-throughput synthetic methods are well-established for chemistries involving liquid- or vapour-phase reagents and have been harnessed to prepare arrays of inorganic materials. The versatile but labour-intensive sub-solidus reaction pathway that is the backbone of the functional and electroceramics materials industries has proved more challenging to automate because of the use of solid-state reagents. We present a high-throughput sub-solidus synthesis workflow that permits rapid screening of oxide chemical space that will accelerate materials discovery by enabling simultaneous expansion of explored compositions and synthetic conditions.

Superionic lithium transport via multiple coordination environments defined by two-anion packing.

Fast cation transport in solids underpins energy storage. Materials design has focused on structures that can define transport pathways with minimal cation coordination change, restricting attention to a small part of chemical space. Motivated by the greater structural diversity of binary intermetallics than that of the metallic elements, we used two anions to build a pathway for three-dimensional superionic lithium ion conductivity that exploits multiple cation coordination environments.

Band Structure Engineering of BiOSeCl for Thermoelectric Applications.

The mixed anion material BiOSeCl has an ultralow thermal conductivity of 0.1 W m K along its stacking axis ( axis) at room temperature, which makes it an ideal candidate for electronic band structure optimization via doping to improve its thermoelectric performance. Here, we design and realize an optimal doping strategy for BiOSeCl from first principles and predict an enhancement in the density of states at the Fermi level of the material upon Sn and Ge doping.

Predicting spinel solid solutions using a random atom substitution method.

Exploration of chemical composition and structural configuration space is the central problem in crystal structure prediction. Even in limiting structure space to a single structure type, many different compositions and configurations are possible. In this work, we attempt to address this problem using an extension to the existing ChemDASH code in which variable compositions can be explored.

Cation Disorder and Large Tetragonal Supercell Ordering in the Li-Rich Argyrodite LiZnSiS.

A tetragonal argyrodite with >7 mobile cations, LiZnSiS, is experimentally realized for the first time through solid state synthesis and exploration of the Li-Zn-Si-S phase diagram. The crystal structure of LiZnSiS was solved from high-resolution X-ray and neutron powder diffraction data and supported by solid-state NMR. LiZnSiS adopts a tetragonal 4 structure at room temperature with ordered Li and Zn positions and undergoes a transition above 411.

Chemical Control of the Dimensionality of the Octahedral Network of Solar Absorbers from the CuI-AgI-BiI Phase Space by Synthesis of 3D CuAgBiI.

A newly reported compound, CuAgBiI, is synthesized as powder, crystals, and thin films. The structure consists of a 3D octahedral Ag/Bi network as in spinel, but occupancy of the tetrahedral interstitials by Cu differs from those in spinel. The 3D octahedral network of CuAgBiI allows us to identify a relationship between octahedral site occupancy (composition) and octahedral motif (structure) across the whole CuI-AgI-BiI phase field, giving the ability to chemically control structural dimensionality.

One class classification as a practical approach for accelerating π-π co-crystal discovery.

The implementation of machine learning models has brought major changes in the decision-making process for materials design. One matter of concern for the data-driven approaches is the lack of negative data from unsuccessful synthetic attempts, which might generate inherently imbalanced datasets. We propose the application of the one-class classification methodology as an effective tool for tackling these limitations on the materials design problems.

Discovery of a Low Thermal Conductivity Oxide Guided by Probe Structure Prediction and Machine Learning.

We report the aperiodic titanate Ba Y Ti O with a room-temperature thermal conductivity that equals the lowest reported for an oxide. The structure is characterised by discontinuous occupancy modulation of each of the sites and can be considered as a quasicrystal. The resulting localisation of lattice vibrations suppresses phonon transport of heat.

Highly Absorbing Lead-Free Semiconductor CuAgBiI for Photovoltaic Applications from the Quaternary CuI-AgI-BiI Phase Space.

Since the emergence of lead halide perovskites for photovoltaic research, there has been mounting effort in the search for alternative compounds with improved or complementary physical, chemical, or optoelectronic properties. Here, we report the discovery of CuAgBiI: a stable, inorganic, lead-free wide-band-gap semiconductor, well suited for use in lead-free tandem photovoltaics. We measure a very high absorption coefficient of 1.

Crystal Structure and Stoichiometric Composition of Potassium-Intercalated Tetracene.

The products of the solid-state reactions between potassium metal and tetracene (K:Tetracene, 1:1, 1.5:1, and 2:1) are fully structurally characterized. Synchrotron X-ray powder diffraction shows that only KTetracene forms under the reaction conditions studied, with unreacted tetracene always present for < 2.

Modular Design via Multiple Anion Chemistry of the High Mobility van der Waals Semiconductor BiOSeCl.

Making new van der Waals materials with electronic or magnetic functionality is a chemical design challenge for the development of two-dimensional nanoelectronic and energy conversion devices. We present the synthesis and properties of the van der Waals material BiOSeCl, which is a 1:1 superlattice of the structural units present in the van der Waals insulator BiOCl and the three-dimensionally connected semiconductor BiOSe. The presence of three anions gives the new structure both the bridging selenide anion sites that connect pairs of BiO layers in BiOSe and the terminal chloride sites that produce the van der Waals gap in BiOCl.

Detection and Crystal Structure of Hydrogenated Bipentacene as an Intermediate in Thermally Induced Pentacene Oligomerization.

6,6',13,13'-Tetrahydro-6,6'-bipentacene (HBP), the intermediate molecule connecting pentacene to previously observed peripentacene and extended pentacene oligomers through the formation of a carbon-carbon bond, is synthesized and crystallographically characterized. Heating pentacene to 300 °C under vacuum for 200 h results in pale golden crystals of HBP and amorphous material containing pentacene oligomers, offering experimental evidence that pentacene preferentially dimerizes at the 6,6'-position. Continued heating of HBP results in co-crystals of 6,13-dihydrogenated pentacene and pentacene and further amorphous pentacene oligomers.

Reactivity of Solid Rubrene with Potassium: Competition between Intercalation and Molecular Decomposition.

We present the synthesis and characterization of the K-intercalated rubrene (CH) phase, KRubrene (KR), and identify the coexistence of amorphous and crystalline materials in samples where the crystalline component is phase-pure. We suggest this is characteristic of many intercalated alkali metal-polyaromatic hydrocarbon (PAH) systems, including those for which superconductivity has been claimed. The systematic investigation of K-rubrene solid-state reactions using both K and KH sources reveals a complex competition between K intercalation and the decomposition of rubrene, producing three K-intercalated compounds, namely, KR, K(RR*), and K R' (where R* and R' are rubrene decomposition derivatives CH and CH, respectively).

BiOCuSeX (X = Cl, Br): A Three-Anion Homologous Series.

Both layered multiple-anion compounds and homologous series are of interest for their electronic properties, including the ability to tune the properties by changing the nature or number of the layers. Here we expand, using both computational and experimental techniques, a recently reported three-anion material, BiOCuSeCl, to the homologous series BiOCuSeX (X = Cl, Br), composed of parent blocks that are well-studied thermoelectric materials. All of the materials show exceptionally low thermal conductivity (0.

Computational Prediction and Experimental Realization of p-Type Carriers in the Wide-Band-Gap Oxide SrZnLi O.

It is challenging to achieve p-type doping of zinc oxides (ZnO), which are of interest as transparent conductors in optoelectronics. A ZnO-related ternary compound, SrZnO, was investigated as a potential host for p-type conductivity. First-principles investigations were used to select from a range of candidate dopants the substitution of Li for Zn as a stable, potentially p-type, doping mechanism in SrZnO.

The preparation of large surface area lanthanum based perovskite supports for AuPt nanoparticles: tuning the glycerol oxidation reaction pathway by switching the perovskite B site.

Gold and gold alloys, in the form of supported nanoparticles, have been shown over the last three decades to be highly effective oxidation catalysts. Mixed metal oxide perovskites, with their high structural tolerance, are ideal for investigating how changes in the chemical composition of supports affect the catalysts' properties, while retaining similar surface areas, morphologies and metal co-ordinations. However, a significant disadvantage of using perovskites as supports is their high crystallinity and small surface area.

Interface control by chemical and dimensional matching in an oxide heterostructure.

Interfaces between different materials underpin both new scientific phenomena, such as the emergent behaviour at oxide interfaces, and key technologies, such as that of the transistor. Control of the interfaces between materials with the same crystal structures but different chemical compositions is possible in many materials classes, but less progress has been made for oxide materials with different crystal structures. We show that dynamical self-organization during growth can create a coherent interface between the perovskite and fluorite oxide structures, which are based on different structural motifs, if an appropriate choice of cations is made to enable this restructuring.

Catalytic Response and Stability of Nickel/Alumina for the Hydrogenation of 5-Hydroxymethylfurfural in Water.

The catalytic response of Ni on Al2O3 obtained from Ni-Al layered double hydroxides was studied for the liquid-phase hydrogenation of hydroxymethyl furfural to tetrahydrofuran-2,5-diyldimethanol (THFDM) in water. The successive calcination and reduction of the precursors caused the removal of interlayer hydroxyl and carbonate groups and the reduction of Ni(2+) to Ni(0). Four reduced mixed oxide catalysts were obtained, consisting of different amount of Ni metal contents (47-68 wt%) on an Al-rich amorphous component.

Photocatalytic water oxidation by a pyrochlore oxide upon irradiation with visible light: rhodium substitution into yttrium titanate.

A stable visible-light-driven photocatalyst (λ≥450 nm) for water oxidation is reported. Rhodium substitution into the pyrochlore Y2 Ti2 O7 is demonstrated by monitoring Vegard's law evolution of the unit-cell parameters with changing rhodium content, to a maximum content of 3 % dopant. Substitution renders the solid solutions visible-light active.