Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40th anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are dee...

Fundamentals and Catalytic Applications of CeO2-Based Materials

Lithium intercalation or insertion materials have been widely investigated in the search for new electrode materials for use in high-voltage rechargeable batteries.1-6 The first commercial Li-ion rechargeable battery contains the layered materials LiCoO2 (Figure 1) and graphite as the cathode (or positive electrode) and anode (or negative electrode), respectively.7 Although this battery is the current standard in many applications including cell phones and laptops, its slow charge and discharge rates and cost have prevented its use in applications that require cheap high power and capacity, such as hybrid electric vehicles and electric vehicles. The toxicity of Co is also an issue. A wide variety of materials have been studied,5,6 which include doped LiCoO2 phases, layered compounds based on the LiCoO2 structure (e.g., LiNiO2 8 and LiNi0.5Mn0.5O2 9,10),

NMR studies of cathode materials for lithium-ion rechargeable batteries.

Spectacular advances in superconductors have taken place in the past two years. The upper temperature for superconductivity has risen from 23 K to 122 K, and there is reason to believe that the ascent is still ongoing. The materials causing this excitement are oxides. Those oxides that superconduct at the highest temperatures contain copper-oxygen sheets; however, other elements such as bismuth and thallium play a key role in this new class of superconductors. These superconductors are attracting attention because of the possibility of a wide range of applications and because the science is fascinating. A material that passes an electrical current with virtually no loss is more remarkable when this occurs at 120 K instead of 20 K.

https://science.sciencemag.org/content/sci/242/4885/1519.full.pdf

Chemistry of High-Temperature Superconductors

Recent advances in aerosol generation of materials are reviewed Gas-to-particle and spray processes (spray pyrolysis) for powder generation and various routes for film generation are discussed from the experimental and theoretical perspectives The range of materials generated by these routes has increased in recent years to include fullerenes and ceramic superconductors Many metals and various oxide and nonoxide ceramics have also been added to the list of materials generated by gas-phase routes Established aerosol routes such as vapor condensation have found widespread applications for generation of nanophase materials The formation of quantum dots via aerosol approaches has also been demonstrated The theoretical understanding of gas-to-particle conversion routes has advanced to include the finite rate of particle fusion or sintering occurring after collisions of particles The modeling of spray pyrolysis systems has provided insight into the control of particle morphology and reactor design In th

https://www.tandfonline.com/doi/pdf/10.1080/02786829308959650

Aerosol Processing of Materials

Hydrogen storage alloys are of particular interest as a novel group in functional materials owing to their potential and practical applications in Ni/MH rechargeable batteries. This review is devoted to the specific alloy families developed for high-energy and high-power Ni/MH batteries in the last decades, especially for EV, HEV and PHEV applications. The scope of the work encompasses principles of Ni/MH batteries, electrochemical hydrogen storage thermodynamics and kinetics, prerequisites for hydrogen storage electrode alloys and recent advances in hydrogen storage electrode alloys. Rare earth AB5-type alloys, Ti- and Zr-based AB2-type alloys, Mg-based amorphous/nanocrystalline alloys, rare earth-Mg–Ni-based alloys and Ti–V-based alloys are highlighted. Additionally, the challenges met in developing advanced hydrogen storage alloys for Ni/MH rechargeable batteries are pointed out and some research directions are suggested.

Advanced hydrogen storage alloys for Ni/MH rechargeable batteries

The compound CaBaLaCu 3 O 6.9 is a tetragonal bulk superconductor with a T c of 80 K. CaBaLaCu 3 O x is isomorphic to tetragonal YBa 2 Cu 3 O x in which the Ca and La ions are both located at the Y- and Ba-site. High temperature X-ray diffraction and thermogravimetric measurements show no indication for “order-disorder” transitions involving the oxygen ions. TEM micrographs of CaBaLaCu 3 O x show no evidence for a / b twinning. The oxygen content and the partial oxygen pressure of CaBaLaCu 3 O x are determined as a function of temperature. The standard enthalpy change for the oxidation reaction, Δ H , is determined as 190.4(0.3) kJ⧸mol O 2 . Transmission electron diffraction patterns show weak but distinct half-order spots indicating an ordering which can be described by a supercell having axes twice as large as the basic unit cell.

Properties of the tetragonal superconductor CaBaLaCu3Ox

High energy density strategies: from hydride-forming materials research to battery integration

The influence of preparation conditions and microstructure on the superconductive properties of single-phase poly-crystalline YBa2Cu3O7−x was investigated by electron probe microanalysis, transmission electron microscopy (TEM), and x-ray powder diffraction as a function of temperature in various ambients supplemented by resistivity and susceptibility measurements. Leaching of Ba was observed when samples were brought in contact with water. The TEM imaging revealed that individual grains have an extremely defect-rich outer shell and an inner core with a domain structure with a and b axes interchanged. The transition temperature Tc was found to decrease with increasing quench temperature in the range 400–900°C. The Tc was observed to be linearly proportional to the difference in the orthorhombic cell parameters (b-a). Further implications are discussed.

Oxygen content, microstructure, and superconductivity of YBa2Cu3O7−x

Compound formation in the Ce2O3-SiO2 system

In the last years, mechanochemical alloying has been proven to be an important technology for the synthesis of intermetallic compounds. This technology has recently been used as a new route for the synthesis of inorganic compounds. The use of mechanochemical synthesis opens possibilities for the synthesis of complex systems at low temperatures. In this paper we discuss the preparation of the powders BaTiO3, Bi0.5Na0.5TiO3 and Ba2NaNb5O15 by mechanochemical synthesis. Phase formation is studied by X-ray powder diffraction. Since partly amorphous powders are obtained the crystallisation behaviour is further investigated by high temperature X-ray powder diffraction. Ceramic pellets have been sintered starting from as-milled powders as well as prefired powders. Microstructure and dielectric properties are characterised.

H.A.M. van Hal

Papers

Properties of the tetragonal superconductor CaBaLaCu3Ox

High energy density strategies: from hydride-forming materials research to battery integration

Oxygen content, microstructure, and superconductivity of YBa2Cu3O7−x

Compound formation in the Ce2O3-SiO2 system

Mechanochemical synthesis of BaTiO3, Bi0.5Na0.5TiO3 and Ba2NaNb5O15 dielectric ceramics