Effect Of Doping Elements Research Articles

Effects of Doped Elements on Electrochemical Performance of Ni(OH)2 Materials

High energy ball milling(HEBM) method was applied to synthesize Ni(OH)2 with different doped elements substitution for Ni2+. The morphology, structure and electrochemical behavior of prepared powders were studied. The results reveal that all the synthesized Ni(OH)2 particles were in sub-micron sizes and greatly agglomerated. Co-, Mg-, Fe- or Mn-doped Ni(OH)2 was of β-phase with 0. 400–0. 500 nm crystal interlayer distance, while Al- and Zn- doped products displayed α-phase with larger crystal interlayer spaces. The electrochemical mechanisms of synthesized Ni(OH)2 electrodes were discussed by EIS spectra. The specific capacity of Co-doped Ni(OH)2 is 245 mA · h · g−1, i.e., 60 mA · h · g−1 higher than that of Al-doped electrode, which has the highest discharging platform of a mid-voltage of 1. 30 V.

High-Throughput Gas Sensing Screening of Surface-Doped In2O3

The effect of various surface doping elements on the electrical and gas sensing properties of indium(III) oxide thick films sensors was investigated by means of high-throughput impedance spectroscopy (HTIS). Some doping elements lead to changes in both the conductivity in air as well as in the gas sensing properties towards oxidizing (NO(2), NO) and reducing (H(2), CO, propene) gases. Correlations between the sensing and the electrical properties in reference atmosphere indicate that the effect of the doping elements can be ascribed to an influence on the oxidation state of the metal oxide surface rather that to an interaction with the respective testing gases. An equation for the description of the temperature-dependent conductivity in air and nitrogen is proposed to describe the oxidation state of the metal oxide surface taking into account sorption of oxygen. Furthermore, a model associating the sensing properties and the oxidation state of the surface layer of the metal oxide based on oxygen spillover from doping element particles to the metal oxide surface is introduced.

The effect of doped elements on the martensitic transformation in Ni–Mn–Ga magneticshape memory alloy

Ni–Mn–Ga alloy is a new actuator material due to the fact that its shape memoryeffect can be controlled by magnetic field in addition to the conventional controlsby temperature and stress. However, the alloy shows relatively low martensitictransformation and Curie temperatures. In this paper, we report the results ofadding small amounts of Fe, Co and Tb to NiMnGa alloys. The effect of smalladditions of these doped elements on the martensitic transformation temperatureis remarkable, but the Heusler structure of the alloys remains unchanged. ForNi50Mn27Ga23−xFex (x = 0,1,2) with partial replacement of Ga by Fe, the martensitic transformationtemperatures increase with increase of the Fe content, and so does the Curietemperature. This phenomenon of increasing both the martensitic transformationtemperatures and the Curie temperature was found for the first time. ForNi47Mn31X1Ga21 (X = Fe,Co), Fe and Co substitution for Mn, Fe increases the martensitic transformationtemperature but decreases the Curie temperature, while Co has the opposite effect. ForNi48Mn33Ga18Tb1, the addition of the rare earth element Tb decreases the martensitic transformationtemperature and the Curie temperature remarkably. Therefore, the transformationtemperatures of the alloys can be improved by these doping methods.

Thermoelectric Properties of TiS2 type materials

ABSTRACTTiS2 belongs to a family of layered compounds that displays promise as a thermoelectric material. At room temperature the thermopower (a) of TiS2 displays an n-type behavior, with a magnitude of ≈ -200 μV/K. The electrical resistivity (ρ), is on the order of 1 mΩ-cm at room temperature and displays a “metallic-like” behavior with dR/dT > 0 from 300 K to 10 K. Thus, these compounds exhibit relatively large power factors (PF = α2/ρ) with a PF ∼30 μW/K2 cm at T = 300 K, which are comparable to the state-of-the art Bi2Te3 type materials, which have a PF ∼40 μW/K2, at T = 330K. These values suggest that further investigations of these systems could be profitable. Thin plate-like crystals of TiS2 are grown by the iodine vapor transport method with planar dimensions of 1 cm and thicknesses of 20 μm or more. In this synthetic approach some dopants can be integrated into the parent compound, effectively providing a route for the tuning of electronic properties. We present here some effects of elemental doping on the electronic properties in these TiS2 based materials.

Sensing characteristics of ZnO-based NO x sensor

Sensing characteristics of ZnO-based sputtered films are studied. The film about 140 nm thick showed high sensitivity to NO x and selectivity against H 2 and CO. The sputtering pressure greatly affected the sensitivity, and the sensitivity maximum was observed at 0.67 Pa. The effect of element doping into ZnO on sensitivity and selectivity to NO x was also studied using co-sputtering technique. Rare earth element doping improved sensitivity and selectivity to NO 2 against NO. Er-doped ZnO film had good selectivity and fast response time to NO 2 above 200°C, and almost linear sensitivity dependence in the sub-ppm concentration range of NO 2.