Elaine Moore

Solid State Chemistry: An Introduction, Fourth Edition

Provides a solid background to a fast-changing field, and also covers areas of new innovation Uses interesting applications to put the topics presented in context Incorporates a two-color layout and a four-color section to facilitate understanding of crystal structures Contains an extensive bibliography and suggestions for further reading to expedite searching for other relevant literature Includes question and answer sets, and an accompanying solutions manual Intended for first- and second-year undergraduates, this introduction to solid state chemistry includes practical examples of applications and modern developments to offer students the opportunity to apply their knowledge in real-life situations. The third edition of Solid State Chemistry: An Introduction has been comprehensively revised and updated. Building a foundation with a thorough description of crystalline structures, the book presents a wide range of the synthetic and physical techniques used to prepare and characterize solids. Other fundamental discussions include: bonding, superconductivity, and electrochemical, magnetic, optical, and conductive properties. The authors have added sections on fuel cells and electrochromic materials; conducting organic polymers, organic superconductors, and fullerenes; mesoporous solids and ALPOs; photonics; giant magnetoresistance (GMR) and colossal magnetoresistance (CMR); and p-wave (triplet) superconductors. The book also includes a completely new chapter, which examines the solid state chemical aspects of nanoscience. Each chapter contains a set of review questions and an accompanying solutions manual is available. Solid State Chemistry: An Introduction, Third Edition is written in a clear, approachable style that enhances the material by integrating its concepts in the context of current applications and areas of promising research.

Magnetic order in perovskite-related SrFeO2F

Perovskite-related strontium orthoferrite, SrFeO3−δ, has been fluorinated by a low temperature reaction with poly(vinylidene fluoride) to give the compound SrFeO2F. X-ray powder diffraction shows that fluorination leads to an expansion of the unit cell which is consistent with partial replacement of oxygen by fluorine and consequent reduction in the oxidation state of iron. Magnetometry experiments in the temperature range 10–400 K showed small aligned moments (0.003 ± 0.000 05 μB per Fe3+ ion at 2 T and 300 K), indicating the absence of ferro- or ferrimagnetism. The 57Fe Mossbauer spectra recorded at temperatures below about 300 K show broadened, but unsplit, sextet patterns whilst spectra recorded above this temperature show clear splitting of the sextet structure and a magnetic ordering temperature of 685 ± 5 K. A model related to the pattern of substitution by fluorine on the octahedral arrangement of oxygen sites around iron is proposed in which SrFeO2F undergoes a magnetic transition at about 300 K from a low temperature state with random spin directions to an antiferromagnetic state.

Tin-, titanium-, and magnesium-doped α-Cr2O3: Characterisation and rationalisation of the structures

Tin- and titanium-doped α-Cr2O3 have been prepared by the calcination of precipitates. Rietveld structure refinement of the X-ray powder diffraction patterns shows that the dopant metals occupy interstitial sites and partially substitute on octahedral chromium sites in the corundum-related α-Cr2O3 structure. Interatomic potential calculations show that such defects are energetically more favourable than the exclusive substitution of chromium or the occupation by the dopant of interstitial sites in α-Cr2O3 with charge balance being achieved by an appropriate number of cation vacancies. However, the attempted incorporation of magnesium within α-Cr2O3 results in the formation of spinel-related MgCr2O4. The observation is rationalised in terms of the greater thermodynamic stability of the spinel-related structure.

Rationalisation of defect structure of tin- and titanium-doped α-Fe2O3 using interatomic potential calculations

Two recently proposed models for the defect structure of tin-doped α-Fe2O3 have been assessed using interatomic potential calculations. The results show that a structure involving tin (or titanium) partially substituting at the octahedral iron sites as well as partially occupying the empty interstitial octahedral sites in corundum-related α-Fe2O3 is more favourable than an alternative model in which the tin (or titanium) ions only occupy the empty interstitial sites.

Preparation and characterisation of tin-doped α-FeOOH (goethite)

Tin-doped α-FeOOH (goethite) has been prepared directly by the hydrothermal processing of a precipitate. The morphology of the crystals, which is reflected in the 57Fe Mossbauer spectra, depends on the pH of the precipitating media. The 119Sn Mossbauer spectra are consistent with a complex microstructure around the octahedrally coordinated tin ions in the goethite structure and are sensitive to the changes in the magnetic structure of α-FeOOH resulting from tin doping. 57Fe Mossbauer spectroscopy and electron microscopy show acicular tin-doped α-FeOOH to be converted to tin-doped α-Fe2O3 with identical morphology by mild heating in air.

Ab initio calculation and NMR spin–echo measurement of 19F chemical shielding in the alkali-metal fluorides

Experimental values of 19F chemical shielding in the series of anhydrous alkali-metal fluorides LiF to CsF are reported. An NMR spin–echo technique is used for the measurements and the results are shown to compare favourably with others, in particular those determined by magic-angle spinning (MAS) techniques, reported in the literature. Ab initio methods of calculating 19F chemical shielding in these primarily ionic materials are then discussed in terms of simplified model systems. For all the alkali-metal fluorides, values of absolute 19F chemical shielding are calculated which are significantly less than the free fluoride ion value. In the specific cases of LiF and NaF reasonable agreement between ab initio calculation and experiment is achieved.

An investigation of the local environments of tin in tin-doped α-Fe2O3

The extended x-ray absorption fine structure (EXAFS) recorded from tin-doped α-Fe2O3, prepared by the mechanical milling of tin dioxide and α-Fe2O3 and by the hydrothermal processing of iron- and tin-containing precipitates, can be interpreted in terms of a model in which tin occupies both substitutional octahedral sites and the interstitial octahedral sites in the corundum-related α-Fe2O3 structure. The EXAFS and 119Sn Mossbauer spectra suggest that structural models derived from x-ray powder diffraction data do not adequately describe the complexity of the local environment of tin in α-Fe2O3. In particular, the EXAFS and 119Sn Mossbauer spectra recorded from materials made by mechanical milling show evidence of more disorder. The 119Sn Mossbauer spectra also indicate that the degree of order in the materials made by both methods is far from perfect and that the microstructural defects are highly sensitive to tin content and the preparative method.

The effect of the NMR spin-echo sequence Py(90°)-τ-Py(180°) in solids containing different dipolar-coupled spin species: applications to KHF2 AND CsHF2

Abstract An experimental investigation of the effect of the NMR sequence P y (90°)-τ- P y (180°) in solids containing different types of dipolar-coupled spin species is reported. The experimental results suggest that the decay of the maximum spin-echo amplitude as a function of pulse spacing depends only on the strength of the homonuclear dipolar interactions. Polycrystalline samples of KHF 2 and CsHF 2 are used as model systems.

Crystal-field theory

We begin our consideration of bonding in transition-metal complexes by looking at crystal-field theory, which is relatively straightforward to apply, and allows us to rationalise, and make predictions about many properties of these molecules.

Prediction of defect structure in lithiated tin- and titanium-doped α-Fe2O3 using atomistic simulation

Abstract The defect structure of lithiated tin- and titanium-doped α-Fe 2 O 3 has been assessed using interatomic potential calculations. Of the models considered for lithiation, a model in which Li + occupies an interstitial site balanced by the reduction of Fe 3+ to Fe 2+ on an Fe 3+ site was found to be more favourable than the substitution of Li + on an Fe 3+ octahedral site balanced by an O 2− vacancy. Insertion of lithium into the interstitial site between two adjacent M 4+ ions was particularly favourable. The calculated lattice parameters decrease on lithiation as has been observed experimentally.