Philip Lightfoot

Bio: Philip Lightfoot is an academic researcher from University of St Andrews. The author has contributed to research in topics: Crystal structure & Neutron diffraction. The author has an hindex of 53, co-authored 383 publications receiving 10549 citations. Previous affiliations of Philip Lightfoot include Natural Resources Canada & Moscow State University.

Crystal Structure of the Polymer Electrolyte Poly(ethylene oxide)3:LiCF3SO3.

Abstract: Ionically conducting polymers (polymer electrolytes) are under intensive investigation because they form the basis of all solid-state lithium batteries, fuel cells, and electrochromic display devices, as well as being highly novel electrolytes. Little is known about the structures of the many crystalline complexes that form between poly(ethylene oxide) and a wide range of salts. The crystal structure is reported of the archetypal polymer electrolyte poly(ethylene oxide)(3):LiCF(3)SO(3), which has been determined from powder x-ray diffraction data. The poly(ethylene oxide) (PEO) chain adopts a helical conformation parallel to the crystallographic b axis. The Li(+) cation is coordinated by five oxygen atoms-three ether oxygens and one from each of two adjacent CF(3)SO(3)(-) groups. Each CF(3)SO(3)(-) in turn bridges two Li(+) ions to form chains running parallel to and intertwined with the PEO chain. There are no interchain links between PEO chains, and the electrolyte can be regarded as an infinite columnar coordination complex.

Ferroelectric-Paraelectric Transition in BiFeO 3 : Crystal Structure of the Orthorhombic β Phase

Abstract: A detailed investigation using variable temperature powder neutron diffraction demonstrates that BiFeO3 undergoes a phase transition from the ferroelectric alpha phase (rhombohedral, R3c) to a paraelectric beta phase (orthorhombic, Pbnm) between 820 degrees C and 830 degrees C. Coexistence of both phases over a finite temperature interval, together with abrupt changes in key structural parameters, confirms that the transition is first order. The beta phase corresponds to a GdFeO3-type perovskite structure.

Cation disorder in ferroelectric Aurivillius phases of the typeBi2ANb2O9(A=Ba, Sr, Ca)

Abstract: The structures of the ferroelectric two-layer Aurivillius phases Bi 2 ANb 2 O 9 (A=Ba, Sr, Ca) have been refined using a combination of X-ray and neutron powder diffraction data. Bi 2 BaNb 2 O 9 is not significantly distorted from idealised symmetry and has been refined in tetragonal space group I4/mmm, a=3.9362(1) and c=25.6582(7) A. The Sr and Ca compounds have been refined in orthorhombic space group A2 1 am, with a=5.5193(3), b=5.5148(3), c=25.0857(6) A and a=5.4833(1), b=5.4423(1), c=24.8984(6) A, respectively. The orthorhombic distortion increases with decreasing A 2+ cation size and originates from bonding requirements at the perovskite A site, in agreement with previous work. However, in contrast to earlier work, we find a partial mixing of Bi and A cations on their respective sites, which increases in the order Ca

Understanding ferroelectricity in layered perovskites: new ideas and insights from theory and experiments

Abstract: ABO3 perovskites have fascinated solid-state chemists and physicists for decades because they display a seemingly inexhaustible variety of chemical and physical properties. However, despite the diversity of properties found among perovskites, very few of these materials are ferroelectric, or even polar, in bulk. In this Perspective, we highlight recent theoretical and experimental studies that have shown how a combination of non-polar structural distortions, commonly tilts or rotations of the BO6 octahedra, can give rise to polar structures or ferroelectricity in several families of layered perovskites. We discuss the crystal chemical origin of the polarization in each of these families – which emerges through a so-called ‘trilinear coupling’ or ‘hybrid improper’ mechanism – and emphasize areas in which further theoretical and experimental investigation is needed. We also consider how this mechanism may provide a generic route for designing not only new ferroelectrics, but also materials with various other multifunctionalities, such as magnetoelectrics and electric field-controllable metal-insulator transitions.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Synthesis of transportation fuels from biomass: chemistry, catalysts, and engineering.

Abstract: 1.0. Introduction 4044 2.0. Biomass Chemistry and Growth Rates 4047 2.1. Lignocellulose and Starch-Based Plants 4047 2.2. Triglyceride-Producing Plants 4049 2.3. Algae 4050 2.4. Terpenes and Rubber-Producing Plants 4052 3.0. Biomass Gasification 4052 3.1. Gasification Chemistry 4052 3.2. Gasification Reactors 4054 3.3. Supercritical Gasification 4054 3.4. Solar Gasification 4055 3.5. Gas Conditioning 4055 4.0. Syn-Gas Utilization 4056 4.1. Hydrogen Production by Water−Gas Shift Reaction 4056

Hybrid porous solids: past, present, future

Abstract: This critical review will be of interest to the experts in porous solids (including catalysis), but also solid state chemists and physicists. It presents the state-of-the-art on hybrid porous solids, their advantages, their new routes of synthesis, the structural concepts useful for their ‘design’, aiming at reaching very large pores. Their dynamic properties and the possibility of predicting their structure are described. The large tunability of the pore size leads to unprecedented properties and applications. They concern adsorption of species, storage and delivery and the physical properties of the dense phases. (323 references)