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Abstract: A clean signature of room temperature multiferroicity in Bi1.2Gd0.1Fe0.8O3 ceramics is observed. Samples were prepared by slow step sintering technique at 850°C. Impurity peaks normally present in original BiFeO3 are completely suppressed with the increase of Bi concentration. Apart from this, structural transformation took place from R3 C to Pn21 a space group and a clear orthorhombic grain growth habit is seen by SEM microstructure. Suppression of impurity phases favors the reduction of mobile oxygen vacancies and hence reduces leakage current for which ferroelectric properties of Bi1.2Gd0.1Fe0.8O3 are enhanced. We argue that the addition of Gd is likely to suppress the spiral spin modulation and at the same time increase the canting angle which favors the enhanced ferromagnetism. Excess Bi is expected to act as point defects and occupy interstitial positions which in turn surrounded by oxygen vacancies and is likely to promote defect driven ferromagnetism with enhanced spin and electric polarization. This finding encourages further revaluation of long-discounted BiFeO3 for multiferroics research. [ABSTRACT FROM AUTHOR]

Nanotwinned α-brass (Cu–30 wt.% Zn) with varying lamellae thickness in the range of 28–170 nm, has been produced by cryorolling (CR). The effect of CR strain ( ɛ CR = 0.2–0.95) on the evolution of homogeneity and refinement in terms of twin lamellae thickness, twin spacing, and their distribution, have been studied using high-resolution transmission electron microscopy (HRTEM) and microhardness measurements. Analysis of X-ray peak broadening has shown that the crystallite size reduces down to 20 nm at ɛ CR = 0.95, which scales with the subgrain size in preexisting twin lamellae, as revealed under HRTEM. The effect of dislocation density and crystallite size on the strength of nanotwinned brass has been correlated using an analytical model. [ABSTRACT FROM AUTHOR]

Abstract We report the evolution of nanocrystalline γ-Ni of 3–7 nm size along with amorphous phase in (Ni 0.50 Fe 0.50) 70.5 B 17.7 Si 7.8 Ti 4 (at.%) upon mechanical alloying of the elemental powder mixture up to 36 h. The effect of milling time on the nanostructure, thermal stability and magnetic properties, have been investigated using x-ray diffraction, differential scanning calorimeter, transmission electron microscope, and vibrating sample magnetometer. The lattice parameter of the γ-Ni phase gradually decreases from 0.3607 nm for 9 h milling down to 0.3554 nm upon 36 h of milling. A first-order magnetic transition has been identified using Arrott plot analysis at Curie temperature (T C) of 608 K along with a large magnetic entropy change (Δ S M) of 0.45 J/kg.K at an applied field of 13800 Oe, and relative cooling power (RCP) of 10.15 J/kg. The effects of nanostructure and phase constituents on the thermal stability, T C , magnetization and coercivity, have been correlated. Highlights • (Ni 0.50 Fe 0.50) 70.5 B 17.7 Si 7.8 Ti 4 (at.%) has been prepared by mechanical alloying. • Heat-treated powder contain nanocrystalline γ -Ni phase with 13–22 nm size. • A first order transition has been identified. • The transition involves a large entropy change of |- ΔS M | = 0.45 J/kg.K at 13800 Oe. [ABSTRACT FROM AUTHOR]

Abstract: The mechanical behaviour upon compression of (Cu0.50Zr0.50)100−x Al x (x =4, 5, 7) rods with 2 and 3mm diameter was systematically studied and compared with the literature data. Fully amorphous bulk metallic glasses (x =5, 7) show little permanent deformation and reproducible yield stress values. The remarkable fracture strain, observed for some apparently X-ray diffraction amorphous samples (x =4), was found to be due to significant amounts (at least 20%) of the B2-CuZr crystalline phase. The effect of possible flaws on the external surface of the rods was evaluated by mechanical testing of either as cast and machined samples. [Copyright &y& Elsevier]