12010-41-2Relevant articles and documents
Investigation of the transport properties and compositions of the Ca2RE7Pn5O5 series (RE=Pr, Sm, Gd, Dy; Pn=Sb, Bi)
Forbes, Scott,Yuan, Fang,Kosuda, Kosuke,Kolodiazhnyi, Taras,Mozharivskyj, Yurij
, p. 148 - 154 (2016)
The Ca2RE7Pn5O5 phases (RE=Pr, Sm, Gd, Dy; Pn=Sb, Bi) were successfully prepared from high temperature reactions at 1225–1300?°C. These phases maintain the same structure types as the parent RE9Pn5O5 phases, except for a Ca/RE mixing. The study and preparation of these phases was motivated by the desire to shift the metallic type properties of the parent RE9Pn5O5 phases to a level more suitable for thermoelectric applications. Electrical resistivity measurements performed on pure, bulk samples indicated all phases to be narrow band gap semiconductors or semimetals, supporting the charge balanced electron count of the Ca2RE7Pn5O5 composition. Unfortunately, all samples are too electrically resistive for any potential usage as thermoelectrics. Electronic band structure calculations performed on idealized RE9Pn5O5 structures revealed the presence of a pseudogap at the Fermi level, which is consistent with the observed electrical resistivity and Seebeck coefficient behavior.
Experimental and theoretical investigation of optical properties of dysprosium monopnictides
Schoenes, J.,Repond, P.,Hulliger, F.,Ghosh, D. B.,De, S. K.,et. al.
, p. 1 - 11 (2008/10/08)
The electronic and optical properties of DyP and DyBi are investigated both experimentally and computationally. The reflectivity spectra, which have been measured up to 12 eV on single crystals, display richly peaked spectral structures that are analogous for both pnictides. From the measured reflectivities the plasma frequencies, Drude relaxation times, and optical conductivity spectra are derived. The fitted Drude conductivity reveals that DyP and DyBi are semimetals with a number of free carriers of about 0.16 and 0.23 per formula unit, respectively. The very-structured experimental optical conductivity spectra are compared to calculated spectra, which are computed using two different approaches to the Dy 4f states: the open-core approach and the L(S)DA + U approach in three versions. These approaches to the 4f states lead to very similar optical spectra. There exists a reasonable agreement between calculation and experiment for a number of the spectral features, which are interpreted by specific interband transitions within the calculated band structure. The agreement between theory and experiment substantiates that the 4f electrons do not participate in the bonding. The differences that remain between theory and experiment for some of the spectral features do not appear to rest on aspects of the treatment of the 4f states, but rather to be intrinsic shortcomings in the description of the other band states.
