In spite of intrinsic limitations, neutron powder diffraction is, and will still be in the future, the primary and most straightforward technique for magnetic structure determination. In this paper some recent improvements in the analysis of magnetic neutron powder diffraction data are discussed. After an introduction to the subject, the main formulas governing the analysis of the Bragg magnetic scattering are summarized and shortly discussed. Next, we discuss the method of profile fitting without a structural model to get precise integrated intensities and refine the propagation vector(s) of the magnetic structure. The simulated annealing approach for magnetic structure determination is briefly discussed and, finally, some features of the program FullProf concerning the magnetic structure refinement are presented and discussed. The different themes are illustrated with simple examples.

Recent advances in magnetic structure determination by neutron powder diffraction

Thermoelectric materials are solid-state energy converters whose combination of thermal, electrical, and semiconducting properties allows them to be used to convert waste heat into electricity or electrical power directly into cooling and heating. These materials can be competitive with fluid-based systems, such as two-phase air-conditioning compressors or heat pumps, or used in smaller-scale applications such as in automobile seats, night-vision systems, and electrical-enclosure cooling. More widespread use of thermoelectrics requires not only improving the intrinsic energy-conversion efficiency of the materials but also implementing recent advancements in system architecture. These principles are illustrated with several proven and potential applications of thermoelectrics.

http://engin1000.pbworks.com/f/TE_rev.pdf

Cooling, heating, generating power, and recovering waste heat with thermoelectric systems.

Multiferroic materials, which show simultaneous ferroelectric and magnetic ordering, exhibit unusual physical properties — and in turn promise new device applications — as a result of the coupling between their dual order parameters. We review recent progress in the growth, characterization and understanding of thin-film multiferroics. The availability of high-quality thin-film multiferroics makes it easier to tailor their properties through epitaxial strain, atomic-level engineering of chemistry and interfacial coupling, and is a prerequisite for their incorporation into practical devices. We discuss novel device paradigms based on magnetoelectric coupling, and outline the key scientific challenges in the field.

Multiferroics: progress and prospects in thin films.

http://sces.phys.utk.edu/mostcited/mc1_1114.pdf

Colossal Magnetoresistant Materials: The Key Role of Phase Separation

Metal Oxides and Oxysalts as Anode Materials for Li Ion Batteries

Oxide pyrochlores — A review

High Dielectric Constant in ACu3Ti4O12 and ACu3Ti3FeO12 Phases

High-efficiency thermoelectric (TE) materials are important for power-generation devices that are designed to convert waste heat into electrical energy.They can also be used in solid-state refrigeration devices.The conversion of waste heat into electrical energy may play an important role in our current challenge to develop alternative energy technologies to reduce our dependence on fossil fuels and reduce greenhouse gas emissions. An overview of various TE phenomena and materials is provided in this issue of MRS Bulletin. Several of the current applications and key parameters are defined and discussed.Novel applications of TE materials include biothermal batteries to power heart pacemakers, enhanced performance of optoelectronics coupled with solid-state TE cooling, and power generation for deep-space probes via radioisotope TE generators.A number of different systems of potential TE materials are currently under investigation by various research groups around the world, and many of these materials are reviewed in the articles in this issue.These range from thin-film superlattice materials to large single-crystal or polycrystalline bulk materials, and from semiconductors and semimetals to ceramic oxides.The phonon-glass/electron-crystal approach to new TE materials is presented, along with the role of solid-state crystal chemistry.Research criteria for developing new materials are highlighted.

/pdf/thermoelectric-materials-phenomena-and-applications-a-bird-s-2e5bqpy32n.pdf

Thermoelectric materials, phenomena, and applications : A bird's eye view

Giant dielectric constant response in a copper-titanate

A new superconductor that displays onset behavior near 120 K has been identified as Bi2Sr3-xCaxCu2O8+y, with x ranging from about 0.4 to 0.9. Single crystal x-ray diffraction data were used to determine a pseudo-tetragonal structure based on an A-centered orthorhombic subcell with a = 5.399 A, b= 5.414A, and c = 30.904 A. The structure contains copper-oxygen sheets as in La2CuO4 and YBa2Cu3O7, but the copper-oxygen chains present in YBa2Cu3O7 do not occur in Bi2Sr3-xCaxCu2O8+y. The structure is made up of alternating double copper-oxygen sheets and double bismuth-oxygen sheets. There are Ca2+ and Sr2+ cations between the adjacent Cu-O sheets; Sr2+ cations are also found between the Cu-O and Bi-O sheets. Electron microscopy studies show an incommensurate superstructure along the a axis that can be approximated by an increase of a factor of 5 over the subcell dimension. This superstructure is also observed by x-ray diffraction on single crystals, but twinning can make it appear that the superstructure is along both a and b axes. Flux exclusion begins in our samples at about 116 K and is very strong by 95 K. Electrical measurements on a single crystal of Bi2Sr3-xCaxCu2O8+y show a resistivity drop at about 116 K and apparent zero resistivity at 91 K.

https://science.sciencemag.org/content/sci/239/4843/1015.full.pdf

Munirpallam A. Subramanian

Papers

Oxide pyrochlores — A review

High Dielectric Constant in ACu3Ti4O12 and ACu3Ti3FeO12 Phases

Thermoelectric materials, phenomena, and applications : A bird's eye view

Giant dielectric constant response in a copper-titanate

A New High-Temperature Superconductor: Bi2Sr3-x Cax Cu2O8+y.