Effects of 4d transition metal Pd doping on the magnetic and superconducting properties of 112-type iron pnictide EuFeAs2

The recently discovered 112-type EuFeAs2 compound that shows complex Eu-spin magnetism provides a new platform to study the interplay between superconductivity (SC) and magnetism in iron pnictide superconductors. In this paper, by substituting Fe with the 4d transition metal Pd, we have successfully synthesized a series of EuFe1-xPdxAs2 (0 ≤ x ≤ 0.08) samples and studied the doping effect on SC and magnetism by means of electrical transport and magnetization measurements. The systematic evolution of the lattice parameters indicates that the Pd atoms have been successfully substituted into the Fe sites. With Pd doping, the Fe-related spin density wave (SDW) transition at TFe m in the parent phase is rapidly suppressed, and SC simultaneously emerges, exhibiting a domelike shape with a maximum onset transition temperature Tonset c of around 18.5 K at x = 0.04. On the other hand, the Eu-related AFM order at TEu m is suppressed very slowly and persists up to x = 0.08, covering the whole SC dome region. Also, the reentrant spin-glass and spin-reorientation transitions below TEu m remain unchanged with Pd doping. All these results indicate that the Eu spins have little effect on SC in EuFe1-xPdxAs2. Finally, based on the resistivity and magnetization data, the T-x phase diagram of EuFe1-xPdxAs2 is constructed and compared with those of 3d transition metals Co/Ni and La doped ones.

Sensing Properties of Vacancy and Pd-Doped Graphene Layer: A First-Principles Study

In this paper, the effect of SO2 adsorption on graphene (intrinsic, vacancy, and doped) is investigated for structural and electronic properties to exploit their potential applications as a gas sensor. The adsorption energy, charge transfer, magnetic moment, density of states, as well as band structure of the SO2 molecule on the vacancy and doped graphene systems are thoroughly discussed. The most stable adsorption site for SO2 on various graphene sheets is also identified and reported. It is found that SO2 molecule is weakly adsorbed on intrinsic graphene (IG) with low adsorption energy. In contrast, vacancy defect and Pd doping significantly enhance the strength of interaction between SO2 molecule and the modified substrates. The dramatic increase in adsorption energy and charge transfer of these systems are expected to induce significant changes in the electrical conductivity of the vacancy graphene (VG) and Pd-doped graphene (PdG) sheets. Furthermore, the results present the potential of Pd-doped vacancy graphene (Pd-VG) for molecular sensor application.

Pd Doping-weakened Intermediate adsorption to Promote Electrocatalytic Nitrate Reduction on TiO2 Nanoarrays for Ammonia Production and Energy Supply with Zinc-Nitrate Batteries

(Photo)Electrochemical nitrogen reduction for ammonia (NH3) production is an appealing alternative to the traditional high-energy Haber-Bosch reaction. However, the future of this approach is bleak because of the ultralow N2...

Martensitic Transformation, Thermal Analysis and Magnetocaloric Properties of Ni-Mn-Sn-Pd Alloys

Martensitic transition and magnetic response of Ni50−x Pdx,y Mn36 Sn14−y (x = 0, 1, 2 and y = 0, 1) Heusler alloys were analysed. The crystalline structure of each composition was solved by X-ray diffraction pattern fitting. For x = 1 and 2, the L21 austenite structure is formed and, for y = 1, the crystallographic phase is a modulated martensitic structure. From differential scanning calorimetry scans, we determine characteristic transformation temperatures and the entropy/enthalpy changes. The temperatures of the structural transformation increase with the addition of Pd to replace Ni or Sn, whereas the austenitic Curie temperature remains almost unvarying. In addition, the magneto-structural transition, investigated by magnetic measurements, is adjusted by suitable Pd doping in the alloys. The peak value of the magnetic entropy changes reached 4.5 J/(kg K) for Ni50Mn36Sn13Pd1 (external field: 50 kOe).

Boosting the Performance of Nano-Ni Catalysts by Palladium Doping in Flow Hydrogenation of Sulcatone

The effect of Pd doping on nano-Ni catalyst hydrogenation aptitude in sulcatone (6-methyl-5-hepten-2-one) hydrogenation was investigated. Obtained results demonstrated that the addition of non-catalytic amounts of Pd to the surface of parent Ni catalyst improves the activity to the extent that it surpassed the activity of 2.16 wt% Pd catalyst (model catalyst) at optimal reaction conditions in the flow hydrogenation of an unsaturated ketone. Pd doping improves hydrogen activation on the catalyst, which was found to be a rate-limiting step using kinetic isotopic measurements and theoretical calculations.

CO Catalytic Oxidation Performances of Pd-Doped BaCeO3

A series of palladium doped barium-based cerium (BaCe1-xPdxO3-δ) catalysts were prepared by the sol–gel method. The catalytic properties of BaCe1-xPdxO3-δ for the oxidation of carbon monoxide were studied. The results show that Pd doping can effectively inhibit the crystal size of catalyst powder, and the specific surface area of the catalyst increases with the increase of doping ratio. Palladium doping significantly improved the catalytic activity of barium ceric acid-based catalyst for CO oxidation. BaCe0.96Pd0.04O3-δ had the best catalytic activity for CO oxidation. After calcination at high temperature, the BaCeO3 perovskite is stable.