[en] Fully epitaxial ZnO(0001)/Fe₃O₄(111) spin injection heterostructures with LaNiO₃(111) conductive buffer layers were fabricated on SrTiO₃(111) by sputtering for the prospective spin injection experiments. Epitaxial growth of Fe₃O₄ can be realized at temperatures higher than 673 K on LaNiO₃(111) substrates. The epitaxial relationship was determined to be ZnO(0001)[112^¯0]∥Fe₃O₄(111)[110]∥LaNiO₃(111)[110]∥SrTiO₃(111)[110]. With the increase of LaNiO₃ growth temperature, the surface of Fe₃O₄ in the hybrid heterostructures becomes flatter whereas the magnetization of ZnO/Fe₃O₄ decreases. A Verwey transition located at ∼ 110 K was observed in all the ZnO/Fe₃O₄ heterostructures, demonstrating the stoichiometry and good crystallinity of Fe₃O₄. - Highlights: ► Epitaxial Fe₃O₄/ZnO bilayers were fabricated on conductive LaNiO₃ by sputtering. ► The surface of Fe₃O₄ becomes flatter with the increase of LaNiO₃ growth temperature. ► The moment jump at Verwey transition decreases with the magnetic field increasing.

[en] This paper discusses radiotracer well logging in the petroleum industry in China. It covers the latest progress in the area. Topics include determination of water intake profile, flow measurement of production fluid, and inter-well fluid tracing. (author)

[en] We investigate the dynamic hysteresis of nanoscale magnetic aggregates by employing Monte Carlo simulation, based on Ising model in non-integer dimensional space. The diffusion-limited aggregation (DLA) model with adjustable sticking probability is used to generate magnetic aggregates with different fractal dimension D. It is revealed that the exponential scaling law A(H₀, ω)∼H₀^α.ω^β, where A is the hysteresis area, H₀ and ω the amplitude and frequency of external magnetic field, applies to both the low-ω and high-ω regimes, while exponents α and β decrease with increasing D in the low-ω regime and keep invariant in the high-ω regime. A mean-field approach is developed to explain the simulated results.

[en] Influences of transformation behavior and precipitates on the deformation behavior of Ni-rich NiTi alloys were thermodynamically and experimentally investigated in present work. According to the thermodynamic analysis, the critical stress presents the same linear relationship with martensitic transformation temperature for all Ni-rich NiTi alloys. The thermodynamic results were demonstrated by the experimental results after aging treatment of Ni-rich NiTi alloys with compositions of 51.5, 51 and 50.5 at% Ni, even for the aged alloys with R phase transformation. Meanwhile, evolution of precipitate size and volume fraction was clearly discussed for Ni-rich NiTi alloys with different aging conditions. Different from the critical stress, transformation behavior presents no obvious influence on the yield stress of the Ni-rich NiTi alloys. The yield stress is mainly determined by Ni₄Ti₃ precipitates, which increases with increasing the precipitate volume fraction and decreases with increasing the precipitate size.

[en] Highlights: • Ni₄Ti₃ precipitation changes to β-Nb precipitation with increasing Nb addition. • Ni₄Ti₃ precipitates cause no change of phase transformation in Nb2 alloy. • β-Nb precipitates decrease Ms in NiTiNb alloy. • The critical yield stresses present same minus linear relationship with Ms. -- Abstract: Ni-rich Ni_xTi_yNb_z (x/y = 1.0645/x-y ≈ 3, z = 0, 2, 4, 6, 9 at.%) alloys were designed and prepared in this work. Based on these alloys, the precipitation evolution of Ni-rich NiTiNb alloys and its influence on phase transformation and mechanical properties were investigated. Ni₄Ti₃ precipitates are observed in Nb0 and Nb2 alloys after aging and furnace cooling. Ni₄Ti₃ precipitation sharply increases Ms in Nb0 alloy, however, causes no obvious change of Ms in Nb2 alloy. With increasing Nb addition, large numbers of β-Nb precipitates densely distribute among eutectic regions of Nb6 and Nb9 alloys. β-Nb precipitates and eutectic β-Nb particles decrease Ms. The critical yield stresses of all Ni-rich NiTiNb alloys are determined by Ms, and present same minus linear relationship with Ms. Precipitation and element variation change Ms and then influence mechanical properties. Meanwhile, this result is demonstrated by thermodynamic analysis.