A. D. Wadsley

Bio: A. D. Wadsley is an academic researcher. The author has contributed to research in topics: Molybdenum bronze & Potassium. The author has an hindex of 1, co-authored 1 publications receiving 135 citations.

Mixed Valence Chemistry-A Survey and Classification

Abstract: Publisher Summary This review is concerned with the neglected class of inorganic compounds, which contain ions of the same element in two different formal states of oxidation. Although the number of references cited in our review show that many individual examples of this class have been studied, yet they have very rarely been treated as a class, and there has never before, to our knowledge, been a systematic attempt to classify their properties in terms of their electronic and molecular structures. In the past, systems containing an element in two different states of oxidation have gone by various names, the terms “mixed valence,” nonintegral valence,” “mixed oxidation,” “oscillating valency,” and “controlled valency” being used interchangeably. Actually, none of these is completely accurate or all-embracing, but in our hope to avoid the introduction of yet another definition, we have somewhat arbitrarily adopted the phrase “mixed valence” for the description of these systems. The concept of resonance among various valence bond structures is one of the cornerstones of modern organic chemistry.

Electronic structure and properties of solids

Abstract: Some of the challenges facing scientists in the area of the electronic structure and properties of solids are reviewed. At a time when computational advances have made possible high-quality calculations, not even conceivable 10 years ago, the article stresses the importance of going beyond the raw output of the calculation and understanding where the result originates. The areas selected for study include the Fermi surface and charge density waves, the stability of solids and the structures of solids under pressure, metal−insulator transitions, the method of moments, superconductivity, and the use of a relatively new technique for the study of chemical bonding, the electron localization function (ELF).

Electronic crystals: an experimental overview

Abstract: This article reviews the static and dynamic properties of spontaneous superstructures formed by electrons. Representations of such electronic crystals are charge density waves (CDW) and spin density waves in inorganic as well as organic low-dimensional materials. A special attention is paid to the collective effects in pinning and sliding of these superstructures, and the glassy properties at low temperature. Charge order and charge disproportionation which occur in organic materials resulting from correlation effects are analysed. Experiments under magnetic field, and more specifically field-induced CDWs are discussed. Properties of meso-and nanostructures of CDWs are also reviewed.

Evidence for a Peierls transition in the blue bronzes K0.30MoO 3 and Rb0.30MoO3

Abstract: X-ray diffuse scattering studies of the quasi one-dimensional blue bronzes K 0.30 MoO 3 and Rb 0.30 MoO 3 show that the metal insulator phase transition observed at T c =180 K is accompanied by a periodic lattice distortion. Analysis of the diffuse scattering observed well above T c shows that the lattice instability involves mainly MoO 6 octahedra. The anisotropy of the electrical resistivity is consistent with a quasi one-dimensional conduction band built on hybridized molybdenum 4d and oxygen pπ orbitals. Together with the electrical properties, the structural results corroborate that the phase transition of the blue bronzes can be viewed as a Peierls distortion Etude par diffusion de rayons X, montrant que la transition metal-isolant observee a T c =180 K s'accompagne d'une distorsion periodique du reseau. Au-dessus de T c , instabilite de reseau principalement pour les octaedres MoO 6 . Interpretation de l'anisotropie de resistivite electrique par une bande de conduction quasi unidimensionnelle construite sur des orbitales hybridees 4d de Mo et pπ de O. Confirmation d'une transition de phase de type Peierls