We report the discovery of superconductivity with T c = 5.5 K in Nb 2 Pd x Se 5 , in which one-dimensional (1D) Nb-Se chains existing along the b-direction hybridize each other to form the conducting b-c * plane. The magnetic susceptibility and specific heat data in both single crystal and polycrystal show evidence of bulk superconductivity. The resistivity, Hall coefficient and magneto-resistance data all indicate the presence of an energy scale T * = ∼50 K, which becomes systematically lowered under hydrostatic pressure and competes with the stabilization of superconductivity. Combined with the band calculation results showing the Fermi surfaces with 1D character, we postulate that the energy scale T * is related to the formation of a density wave 5
We report the observation of multiferroicity in a clinopyroxene NaFeGe(2)O(6) polycrystal from the investigation of its electrical and magnetic properties. Following the previously known first magnetic transition at T(N1) = 13 K, a second magnetic transition appears at T(N2) = 11.8 K in the temperature dependence of the magnetization. A ferroelectric polarization starts to develop clearly at T(N2) rather than T(N1) and its magnitude increases up to ~13 μC m(-2) at 5 K, supporting the idea that the ferroelectric state in NaFeGe(2)O(6) stems from a helical spin order stabilized below T(N2). When a magnetic field of 90 kOe is applied, the electric polarization decreases to 9 μC m(-2) and T(N2) slightly increases by 0.5 K. At intermediate magnetic fields, around 28 and 78 kOe, anomalies in the magnetoelectric current, magnetoelectric susceptibility, and field derivative of magnetization curves are found, indicating field-induced spin-state transitions. Based on these electrical and magnetic properties, we provide a detailed low temperature phase diagram up to 90 kOe, and discuss the nature of each phase of NaFeGe(2)O(6).
A hybrid supercapacitor (HSC) is a supercapacitor (SC) based on two different electrode materials. One electrode is based on battery type faradic reactions (also known as extrinsic pseudocapacitor), and the other is based on the electric double-layer capacitor (non-faradic, known as intrinsic pseudocapacitor). In HSC, generally negative electrode material includes carbonbased materials (such as activated carbon, carbon nanotubes (CNT's) and graphene), metal oxides (such as V2O5 and MoO3), and their composites, while positive electrode materials are Ni, Co-based, mixed metal oxide, binary metal-based, layered double hydroxide (LDH) based materials etc. The synergy between high conductivity, specific surface area of negative electrode and architectures, heterostructures of positive electrodes is used to improve the overall electrochemical performances of the HSC's device. In this review, the basic charge storing mechanisms, a method for determination of capacitive and diffusion-controlled contribution, are explained. This review highlights the importance of hybrid solid-state supercapacitors (HSSC's) as energy storage devices. Finally, recent advancement in the HSSC fields is discussed and will guide future work in the HSSC field.
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