9 research outputs found
Influence of the carbon substitution on the critical current density and AC losses in MgB2 single crystals
The DC magnetization and AC complex magnetic susceptibilities were measured
for MgB2 single crystals, unsubstituted and carbon substituted with the
composition of Mg(B_0.94C_0.06)2. The measurements were performed in AC and DC
magnetic fields oriented parallel to the c-axis of the crystals. From the DC
magnetization loops and the AC susceptibility measurements, critical current
densities (Jc) were derived as a function of temperature and the DC and AC
magnetic fields. Results show that the substitution with carbon decreases Jc at
low magnetic fields, opposite to the well known effect of an increase of Jc at
higher fields. AC magnetic losses were derived from the AC susceptibility data
as a function of amplitude and the DC bias magnetic field. The AC losses were
determined for temperatures of 0.6 and 0.7 of the transition temperature Tc, so
close to the boiling points of LH2 and LNe, potential cooling media for
magnesium diboride based composites. The results are analyzed and discussed in
the context of the critical state model.Comment: 10 pages, 7 figures, 1 tabl
Influence of carbon on intraband scattering in Mg(B1-xCx)2
We report data on the Hall coefficient (RH) of the carbon substituted
Mg(B1-xCx)2 single crystals with x in the range from 0 to 0.1. The temperature
dependences of RH obtained for the substituted crystals differ systematically
at low temperatures, but all of them converge to the value of 1.8 x 10^-10
m^3/C at room temperature. The RH(T) data together with results of the
thermoelectric power and electrical resistivity measurements are interpreted
within a quasi-classical transport approach, where the presence of four
different conducting sheets is considered. The main influence of the carbon
substitution on the transport properties in the normal state is associated with
enhanced scattering rates, rather than modified concentration of charge
carriers. Presumably the carbon substitution increases the electron-impurity
scattering mainly in the pi band.Comment: 16 pages, 3 figure
Optical, Dielectric and Magnetic Properties of La1−xNdxFeO3 Powders and Ceramics
Nanocrystalline La1−xNdxFeO3 powders with different concentrations of Nd3+ have been synthesized using a modified Pechini method. Their structures were studied by X-ray powder diffraction (XRD). Furthermore, La1−xNdxFeO3 nanoceramics were prepared using a high pressure sintering technique. The luminescence spectra of the powders were investigated as a function of concentration of active dopant to check the possible energy transfers observed due to Nd3+ concentration changes. The electrical and magnetic properties of the powders and ceramics were investigated to determine the effect of Nd3+ doping on the dielectric permittivity and magnetization in the wide frequency range. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 778070—TransFerr—H2020-MSCA-RISE-2017. Part of the work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement
Thermoelectric Power of Single Crystals Doped with Holes and Electrons
The thermoelectric power of single crystals, non-substituted, single-substituted with C, and co-substituted with C and Li, was investigated in the temperature range from 10 to 300 K. Both the in-plane and the out-of-plane thermoelectric powers are positive for non-substituted crystals and both and change a sign for crystals doped with electrons when C is substituted for B in the amount larger than 6 at.%. The substitution of C, which supplies electrons mainly into the σ band, reduces the thermoelectric power anisotropy, most likely by increasing the interband scattering. When Li is additionally co-substituted for Mg, remains unchanged but increases substantially. The Li substitution donates holes into the π band rather than into the σ band and in this way modifies the π band properties, including the possible increase in the intraband scattering
Tailoring structure and electric transport properties of the magnetic iron boron nitride nanoceramics
Influence of precursor type on structural, morphological, dielectric and magnetic properties of TiO2 nanoparticles
BARCSoySNP23: a panel of 23 selected SNPs for soybean cultivar identification
This report describes a set of 23 informative SNPs (BARCSoySNP23) distributed on 19 of the 20 soybean linkage groups that can be used for soybean cultivar identification. Selection of the SNPs to include in this set was made based upon the information provided by each SNP for distinguishing a diverse set of soybean genotypes as well as the linkage map position of each SNP. The genotypes included the ancestors of North American cultivars, modern North American cultivars and a group of Korean cultivars. The procedure used to identify this subset of highly informative SNP markers resulted in a significant increase in the power of identification versus any other randomly selected set of equal number. This conclusion was supported by a simulation which indicated that the 23-SNP panel can uniquely distinguish 2,200 soybean cultivars, whereas sets of randomly selected 23-SNP panels allowed the unique identification of only about 50 cultivars. The 23-SNP panel can efficiently distinguish each of the genotypes within four maturity group sets of additional cultivars/lines that have identical classical pigmentation and morphological traits. Comparatively, the 13 trinucleotide SSR set published earlier (BARCSoySSR13) has more power on a per locus basis because of the multi-allelic nature of SSRs. However, the assay of bi-allelic SNP loci can be multi-plexed using non-gel based techniques allowing for rapid determination of the SNP alleles present in soybean genotypes, thereby compensating for their relatively low information content. Both BARCSoySNP23 and BARCSoySSR13 were highly congruent relative to identifying genotypes and for estimating population genetic differences