Thermoelectric properties of SrTiO3doped with 8%Pm at Sr site were investigated using density functional theory and generalized gradient approximation. The transport properties were calculated based on BoltzTraP code at temperature range 300-1200K. In electronic properties study Fermi level were shifted to conduction band region due to high contribution 4f orbital in Pm. Present study thermoelectric figure of merit ZT result was 0.395 at 300K and 0.638 at 1200K. This shows a considerably good value of ZT for SrTiO3as n-type oxide. Compared to previous work, ZT were at the range of 0.21 - 0.37 for temperature of 300-1000K in Pr, La, Ta and Ho.
In this project, iron mill scale has been used to produce iron powder that can be used within the Powder Metallurgy process. To achieve this objective, the iron mill scale needs to be refined. This involve the work of grinding the iron mill scale to an effective particle size, which is 300μm. Latter, the grounded iron mill scale will undergo the magnetic separation process. The purpose of this process is to remove any non-magnetic material. Than the following process is to fully oxidize and reduce the iron mill scale to form pure iron powder. From this step an optimum value for maximum heating temperature, heating rate and heating cycle was determined. Than in order to determine whether the oxidation and the reduction process have completely achieved their objective, the iron oxide and the iron powder that have been produced from both process, was characterized using X-Ray Diffraction Analysis (XRD) and X-Ray Florescent Analysis (XRF) technique. From the oxidation process, it is obvious that sample C gave higher oxidation percentage, which is 11.22%. While Reduction 2 shows the desirable result, which is 29.51% of reduction, involving a low cost compared to other reduction process.
The relations between the milling periods with the iron mill scale particle size have been studied. Iron mill scale has been chosen for this research due to the nature of itself, as a by-product. From this research, the average optimum size for the final iron mill scale particle size intended to produce is at 300 μm. Raw iron mill scale received from the industries was in the form of chip with the average size of 10 mm across and 1.5 mm thickness. Three different samples from three different steel mill companies have been used for this study. Rolling ball mill has been used to mill the iron mill scale with two different milling periods, which were two hours and six hours. After the milling process, the iron mill scale was sieved using sieving machine to a few specified grating sizes. Weight of each sample collected from each grating size was calculated in order to get the percentage of the particle size distribution of the iron mill scale after the milling process. Sample collected from Steel Mill 1 (SM1) and Steel Mill 3 (SM3) showing finer particle size produced after the milling period of six hours as compared to two hours. However sample from Steel Mill 2 (SM2) showing different trend of particle size collected as compared to SM1 and SM3. Coarser particle size was collected after the milling periods of six hours as compared to two hours. Characterization process have been conducted to all mill scale samples from each steel mill company in order to determine the relationship between the mill scale properties and the result gathered after the milling process.
The search for clean energy conversion technologies promotes the study of thermoelectric materials. In this paper, the electronic structure and thermoelectric properties of CaMnO3 doped with 17% V using first principles calculations and semi-classic Boltzmann theory on Ca site as well as Mn sites. The G-type AFM magnetic ordering is most stable among four types of magnetic ordering for CaMnO3 and V doped CaMnO3 a Mn site while FM ordering was found for V doped CaMnO3 at Ca site. The calculated partial density of states plot shows half metallic and metallic behavior for V doped at A site and B site respectively. Thermoelectric property calculations show that the magnitude of Seebeck coefficient decreased with V doping at both sites with V doping at Mn sites has the lowest magnitude of Seebeck coefficient. All samples show the negative Seebeck coefficient indicating n type behavior. The magnitude of conductivity increases with V doping with the highest magnitude belong to V doped at Mn site. The magnitude of thermal conductivity also increased with V doping at Mn site, but shows a reduction for V doping at Ca site. The figure of merit (ZT) for V doping at Ca site shows a significant improvement over intrinsic CaMnO3 at 0.14 at 1000 K. However, V doping at Mn site sample shows a reduction of ZT at 0.0028 for CaMnO3 at 1000 K which is much lower than CaMnO3 at 0.08.
Effect on mechanical properties of glass reinforced epoxy (GRE) pipe filled with different geopolymer filler molarity for piping application AIP Conference Proceedings 1835, 020042 (2017) -O-Mn 3+ bond angle affect the magnetoresistance ratio which reduce to 16.2 % for x=0.125 from 99.9 % for x=0.0 and 0.25.
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