A simple, convenient, low temperature route to grow polycrystalline copper selenide thin films

There have been major advances in solid state and materials chemistry in the last two decades and the subject is growing rapidly. In this account, a few of the important aspects of materials chemistry of interest to the author are presented. Accordingly, transition metal oxides, which constitute the most fascinating class of inorganic materials, receive greater attention. Metal-insulator transitions in oxides, high temperature superconductivity in cuprates and colossal magnetoresistance in manganates are discussed at some length and the outstanding problems indicated. We then discuss certain other important classes of materials which include molecular materials, biomolecular materials and porous solids. Recent developments in synthetic strategies for inorganic materials are reviewed. Some results on metal nanoparticles and nanotubes are briefly presented. The overview, which is essentially intended to provide a flavour of the subject and show how it works, lists references to many crucial reviews in the recent literature.

Novel materials, materials design and synthetic strategies: recent advances and new directions

Cobalt chromite (CoCr2O4) is a potential multiferroic material In order to understand the temperature dependent magnetic transitions on particle morphology, here we prepared CoCr2O4 nanoparticles by sonochemical technique We used powder x-ray diffraction, transmission electron microscopy, selected area electron diffraction, superconducting quantum interference device magnetometer, and ac susceptibility measurement techniques for characterization The low-temperature magnetic behavior of CoCr2O4 nanoparticles have been investigated in more detail While the bulk CoCr2O4 exhibits two magnetic transitions viz, Tc≈98 K and Ts≈26 K, the nanoparticles here showed a Tc≈84 K and Ts≈25 K We tentatively attribute this shift in Tc to finite size effects

Magnetic properties of sonochemically synthesized CoCr2O4 nanoparticles

In this paper we discuss magnetic ordering in three-dimensional crystals in which Heisenberg exchange interactions appear to dominate. Particular emphasis is placed on systems with strong competing exchange interactions, called frustrated spin systems. In the absence of such competition, one finds collinear spin ordering. However, strong competing interactions lead to non-collinear structures, often spirals and many variations thereof. The problem of understanding the origin and physical properties of such spin states within the classical Heisenberg model has been intensively addressed by a large community of researchers over the last 2–3 decades. The study of such problems actually began about five decades ago, and led to a large body of literature that has been overlooked in the publications of the last 2–3 decades (with two very recent exceptions). The early work established important fundamental concepts, including an unconventional theoretical approach, the generalized Luttinger–Tisza method and the ...

Spin ordering in three-dimensional crystals with strong competing exchange interactions

Chemical deposition of thallium doped cadmium selenide thin films and their characterization

1. Lattice Dynamics.- Theory of Small Oscillations.- Effect of Lattice Symmetry.- Density of Vibrational States.- Vibrational Thermodynamic Properties of Crystals.- X-ray and Neutron Scattering.- 2. Cohesive Energies of Ionic Solids.- Born-Haber Cycle.- Born Treatment of Ionic Solids.- Some Related Aspects.- 3. Defect Chemistry and Non-Stoichiometric Compounds.- Point Defect Equilibria in Crystals.- The Systematica of Non-Stoichiometric Compounds.- Grossly Non-Stoichiometric Compounds.- Ferrous Oxide: A Case History.- Strong Defect Ordering: Intermediate Superstructure Phases.- Elimination of Defects: Crystallo graphic Shear.- Imperfections of Ordered Structures (Lattice Imaging).- Conclusions and Outstanding Problems.- 4. Theory of Point Defects in Ionic Crystals.- to Point Defects in Ionic Crystals.- Experimental Studies of Point Defects.- Theoretical Calculations of the Formation Energies of Schottky Defects.- Defect Interaction Energies.- Migration Energies.- Interstitial Defects.- Concluding Remarks.- 5. Dielectric Properties.- Definitions and Units.- Mechanisms of Polarization.- Alternating Current Phenomena.- Ferroelectrics.- 6. Magnetism.- Non-Interacting Atoms.- Magnetic Interactions.- Long-Range Order.- Spiral Configurations.- Magnetic Atoms in a Crystal.- Superexchange Interactions.- Collective d-Electron Model.- 7. Neutron Diffraction and Solid State Properties.- Thermal Neutrons.- Elastic Scattering.- Inelastic Scattering.- Conclusions.- 8. Magnetic Resonance.- Nuclear Moments end Nuclear Magnetic Resonance.- Spin-Lattice Relaxation.- Bloch Equations and Transverse Relaxation.- Experimental Arrangements.- NMR in Non-metallic Solids.- Quadrupolar Splittings in NMR.- NMR in Metals.- Chemical Shift and Spin Coupling in Solids.- Pure Quadrupole Resonance in Solids.- Electron Paramagnetic Resonance.- Concluding Remarks.- 9. Nuclear Magnetic Resonance in Superconductors and Dilute Alloys.- NMR in Superconductors.- NMR in Dilute Alloys.- 10. Magnetostriction in Materials.- Behaviour of Common Materials.- Conclusions.- 11. Mossbauer Effect and Dynamics of Atomic Motion in Solids.- Resonance Fluorescence.- Mossbauer's Experiment.- Resonance Absorption of Gamma Rays and Dynamics of Atomic Motion.- Experimental Results.- Concluding Remarks.- 12. Positron Annihilation in Solids.- Methods and Results.- 13. Elements of Order-Disorder Theory and Diverse Applications.- Statement of the Problem.- The Zero Order Approximation (Langmuir Isotherm).- The Fermi-Dirac Distribution Function.- Decomposition of the Lattice into Subfigures.- The Fowler-Guggenheim Adsorption Isotherm.- Thermodynamic Properties of Binary Mixtures in the Bragg-Williams Approximation.- 14. Diffusion in Solids.- The Diffusion Coefficient.- Intrinsic Diffusion Coefficients.- Self-Diffusion Coefficients.- Experimental Procedures.- 15. Ionic Conductivity.- Conduction Mechanisms in Ionic Crystals.- Anisotropy of Conduction in Ionic Crystals.- 16. Inorganic Glasses.- Constitution of Glass.- Glass formation.- Inorganic Glass Forming Systems.- Transport Properties of Glasses.- 17. Electrical Properties of Solid Catalysts.- Historical Introduction.- Classification of Solid Catalysts based on Electronic Properties.- Inverse Mixed Catalysts.- Conclusions.- 18. Dislocations and Solid State Reactions.- Dislocations, Their Structure and Properties.- The Role of Dislocations in Chemical Reactions.- 19. Solid State Reactions.- Role of Defects in the Reactivity of Solids.- Solid-Gas Reactions: Oxidation of Metals.- Solid-Solid Reactions.- Thermal Decomposition of Solids.- 20. Band and Transport Theories in Solids.- to Band Structure Concepts (Particle-in-the-Box).- Kronig-Penney Model.- Bloch Functions for the Circular Chain.- Band Structure for a Circular Chain in the Tight Binding Approximation.- Pauli Exclusion Principle and Fermi-Dirac Statistics.- Heat Capacity of a Metal.- Classification of Materials.- Elementary Discussion of Yarious Transport Phenomena.- Fermi Levels and Conductivity in Intrinsic and Extrinsic Semiconductors.- Transport Effects in Materials Characterized by 'Hopping' Electrons.- Brief Survey of Experimental Results.- 21. Spectroscopy of Metals and Semiconductors.- Macroscopic Theory and Experimental Methods.- Microscopic Theory of Optical Properties.- Optical Properties of Metals.- Optical Properties of Semiconductors.- Conclusions.- 22. Phase Transformations in Solids.- Thermodynamic Considerations.- Structural Changes in Transformations.- Kinetics of Transformations.- Order-Disorder Transitions.- Martensite Transformations.- Ferroelectric Transformations.- Magnetic Transitions.- Semiconductor-Metal Transitions.- High Pressure Transformations.- Born Treatment of Phase Transformations in Alkali Halides.- Comments on Experimental Techniques.

C. N. R. Rao

Papers

Modern Aspects of Solid State Chemistry