ZIB

Hits per page

hits 1 - 2 | 2 hits

Sorting

Electronic Resource

Structural and electronic transport properties of polycrystalline p-type CoSb3 (1998)

Anno, H. ; Hatada, K. ; Shimizu, H. ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 83 (1998), S. 5270-5276

add to mindlist on the mindlist

Details

ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: The structural and electronic transport properties of polycrystalline p-type CoSb3 with different grain sizes (about 3 and 3×102 μm) were investigated. The magnetic susceptibility was also measured. Samples were characterized by x-ray diffractometry, electron-probe microanalysis, and optical microscope observation. Samples were found to be stoichiometric and homogeneous. The Hall carrier concentration of the samples is of the order of 1018 cm−3 and weakly dependent on the temperature. The temperature dependence of the Hall mobility suggests that the predominant scattering mechanism drastically changes depending on grain size: for large grain size a combination of the neutral impurity scattering and the acoustic phonon scattering, and for small grain size the ionized impurity scattering. The magnetic susceptibility was found to be essentially diamagnetic independently of grain size, and to vary slightly with temperature. The weak temperature dependence of the susceptibility can be explained by taking into account the three contributions of ion cores, conduction electrons, and trace amounts of magnetic impurities. From the analysis of the susceptibility due to conduction electrons, the band gap energy was determined to be about 70–80 meV, consistent with a recent band structure calculation. Although the effects of nonmagnetic impurity phases segregated (Sb, etc.) on the scattering mechanism are not clear, the grain size is one of the key factors determining the transport properties of polycrystalline CoSb3. © 1998 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.367350

Permalink

Library	Location	Call Number	Volume/Issue/Year	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Optically active and highly threodiisotactic poly(triphenylmethyl crotonate) with conformational chirality (1995)

Ute, K. ; Asada, T. ; Nabeshima, Y. ; [et al.]

Weinheim : Wiley-Blackwell

Acta Polymerica 46 (1995), S. 458-462

add to mindlist on the mindlist

Details

ISSN: 0323-7648

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Notes: Polymerization of triphenylmethyl crotonate with a 9-fluorenyllithium/(S,S)-(+)-2,3-dimethoxy-1,4-bis(dimethylamino)-butane complex in toluene at -78°C gave a highly threodiisotactic polymer. The polymer had a trimodal distribution of molecular weight (MW); the highest-MW part showed a small negative optical rotation and the other two showed positive rotation. The middle-MW fraction (DP=21.5, M̄w/M̄n=1.07) had an [α]D of +53.3°. The optical rotation of this fraction decreased gradually in chloroform at 60°C while the GPC curve of the fraction remained unchanged. The loss of optical activity was ascribed to the racemization through helix sense reversal of the polymer chain. The rate of the decrease in optical rotation obeyed first-order kinetics. From the rate constants at 50 and 60°C, the activation enthalpy for the helix reversal was determined to be 28.4 kcal/mol.

Additional Material: 6 Ill.