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High-entropy pyrochlore iridates A2Ir2O7 with multiple trivalent A cations were synthesized. The parent ternary A2Ir2O7 displays a variety of electronic phases depending on the size of A cations; Pr2Ir2O7 with a large A cation shows semimetallic behavior down to low temperatures, whereas A2Ir2O7 with smaller A cations, such as Nd2Ir2O7 and Eu2Ir2O7, displays a (semi)metal to magnetic insulator transition as a function of temperature. By further reducing the A cation size, smaller than Y3+, A2Ir2O7 becomes a Mott insulator, and long-range magnetic order takes place below room temperature. The metal–insulator transition and magnetic ordering turned out to be robust against strong disorder induced by the mixing of more than five A-cations in the high-entropy A2Ir2O7. The transition temperatures were found to scale with the average ionic radius of multiple A-cations. In contrast, high-entropy A2Ir2O7 including Bi3+ exhibits metallic behavior down to 2 K, which is likely associated with the presence of oxygen vacancies as in the parent Bi2Ir2O7. Although these indicate that the overall electronic structure of A2Ir2O7 remains intact in the presence of high-entropy configuration at the A-site, the transport properties suggest that fine details of the band structure may be modulated by local distortion. Strong disorder at the A-site of complex oxides may be exploited as a tool to control electronic properties. [ABSTRACT FROM AUTHOR]

The recently-discovered high pressure material MnFe3O5 displays a rich variety of magnetically ordered states on cooling. Fe spins order antiferromagnetically below a Néel transition at 350 K. A second transition at 150 K marks Mn spin order that leads to spin canting of some of the Fe spins and ferrimagnetism. A further transition at 60 K is driven by charge ordering of Fe2+ and Fe3+ over two inequivalent Fe sites, with further canting of all spins. Electrical resistivity measurements reveal semiconducting behaviour in MnFe3O5 with a change in activation energy at 285 K. [ABSTRACT FROM AUTHOR]

Examines polyolefin-organoclay nanocomposites containing a synthetic tetrasilisic fluoromica. Preparation of the nanocomposites from metallocene-catalyzed and conventional Ziegler-Natta-catalyzed linear low-density polyethylenes; Effects of maleic-anhydride grafted compatibilizer; Crystallization; Dynamic mechanical thermal analysis.

An account is given of an investigation into the peel strength of wool fabrics bonded with different compositions of vinyl acetate-ethylene copolymer latices for which a 180° peel-testing method was used. The effects on the bond strength of changes in viscosity, thickness, contact time, contact pressure, and method of application of the adhesive are also examined. Modifications to the surface of the wool fibre were found to have a significant effect on the bond strength, as did the effective area of the superimposed fabrics. [ABSTRACT FROM AUTHOR]

The recently-discovered high pressure material MnFe 3 O 5 displays a rich variety of magnetically ordered states on cooling. Fe spins order antiferromagnetically below a Néel transition at 350 K. A second transition at 150 K marks Mn spin order that leads to spin canting of some of the Fe spins and ferrimagnetism. A further transition at 60 K is driven by charge ordering of Fe 2+ and Fe 3+ over two inequivalent Fe sites, with further canting of all spins. Electrical resistivity measurements reveal semiconducting behaviour in MnFe 3 O 5 with a change in activation energy at 285 K.