Articles you may be interested inTemperature-and field-dependent critical currents in [(Bi,Pb)2Sr2Ca2Cu3Ox]0.07(La0.7Sr0.3MnO3)0.03 thick films grown on LaAlO3 substrates

We prepared a series of Mg 1Ϫx Zr x B 2 bulk samples with different x values by the solid-state reaction at ambient pressure and investigated the effects of the Zr doping on phase compositions, microstructure, and flux pinning behavior. The results indicate that the a axis increases with the increase of the Zr doping and the c axis remains unchanged. ZrB 2 phases form and a small amount of Zr atoms may substitute Mg in Zr-doped samples. Critical temperature drops with increasing the Zr doping. It is found that critical current density J c can be significantly enhanced by the Zr doping and the best data are achieved in Mg 0.9 Zr 0.1 B 2 . For this sample, J c values are remarkably improved to 1.83ϫ10 6 A/cm 2 in the self field and 5.51ϫ10 5 A/cm 2 in 1 T at 20 K. Also, the irreversibility field is increased by the Zr doping. The high density, fine grain size of MgB 2 , and small ZrB 2 particles in Zr-doped samples may be responsible for the enhancement of J c . Also, the field dependence of J c at different temperatures was briefly discussed.

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We use first-principles calculations to systematically explore the potential of transition metal atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, and Au) embedded in buckled monolayer g-CN as single-atom catalysts. We show that clustering of Sc and Ti on g-CN is thermodynamically impeded and that V, Cr, Mn, and Cu are much less susceptible to clustering than the other TM atoms under investigation. Strong bonding of the transition metal atoms in the cavities of g-CN and high diffusion barriers together are responsible for single-atom fixation. Analysis of the CO oxidation process indicates that embedding of Cr and Mn in g-CN gives rise to promising single-atom catalysts at low temperature.