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Smart susceptors are being developed for use as tooling surfaces in molding machines that use apply electro-magnetic induction heating to mold and form plastics or metal powders into structural parts, e.g., on aerospace and automotive manufacturing lines. The optimal magnetic materials for the induction heating process should have large magnetization, high magnetic permeability, but also small thermal expansion coefficient. The Fe0.65Ni0.35 invar alloy with its negligible thermal expansion coefficient is thus a natural choice for this application. Here, we use density functional theory as implemented through the Korringa-Kohn-Rostoker method within the coherent-potential approximation, to design new alloys with the large magnetization desired for smart susceptor applications. We consider the Fe0.65-xNi0.35-yMx+y alloys derived from Fe0.65Ni0.35 invar adding a third element M=Sc, Ti, V, Cr, Mn, or Co with concentration (x + y) reaching up to 5 at. %. We find that the total magnetization depends linearly on the concentration of M. Specifically, the early 3d transition metals from Sc to Cr decrease the magnetization with respect to that of the invar alloy whereas Mn and Co increase it. [ABSTRACT FROM AUTHOR]

Experimental measurements of optical and electronic properties and local-density approximation (LDA) calculations on polycrystalline Ga3-xIn5+xSn2O16--the so-called "T-phase" in the Ga2O3-In2O3-SnO2 ternary system--have revealed it to be a good candidate for n-type transparent conducting oxide applications, particularly in the replacement of tin-doped indium oxide as a1 transparent electrode in organic photovoltaics. Room temperature conductivity of over 1000 S cm-1 was measured in polycrystalline bulk samples. Band structure calculations reveal a highly dispersed conduction band, corresponding to an electron effective mass of about 0.2me. Normalized carrier mobility and concentration trends indicate that conductivity changes in T-phase are attributable to changes in carrier concentration, with mobility remaining relatively constant through the range of processing conditions and sample composition. Screened exchange LDA calculations yield a fundamental band gap of about 2.60 eV. A relatively constant optical band gap in the range of 2.9-3.0 eV along the range of T-phase composition was measured by diffuse re?ectance of bulk samples, whereas ab-initio simulations predict a decreasing fundamental band gap with increasing In-to-Ga ratio. This is attributed to an increasing Burstein-Moss shift--corresponding to increasing free electron concentration--with increasing In-to-Ga ratio. [ABSTRACT FROM AUTHOR]

For a material to be a good p-type transparent conducting oxide (TCO), it must simultaneously satisfy several design principles regarding its bulk and defect phase thermochemistry, its optical absorption spectrum, and its electric transport properties. Recently, we predicted Ag3VO4 to be p-type but with low conductivity and an optical band gap not large enough for transparency. To improve on the transport and optical properties of Ag3VO4, we searched an extended material space including quaternary compounds based on Ag, V, O, and an additional atom for a new candidate p-type TCO. From this set of quaternary materials, we selected KAg11(VO4)4, a known oxide with a crystal structure related to that of Ag3VO4. Notably, one could expect a possible enhancement of the concentration of hole producing Ag-vacancy defects in KAg11(VO4)4 due to its different local geometries of Ag atoms (2- and 3-fold coordinated) with respect to the 4-fold coordinated Ag atoms in Ag3VO4. By performing first-principles calculations, we found that KAg11(VO4)4 is an intrinsic p-type conductor and can be synthesized under conditions similar to those predicted for the synthesis of Ag3VO4. However, we predict that the intrinsic hole content in KAg11(VO4)4 is similar to that in Ag3VO4 even though KAg11(VO4)4 contains 2- and 3-fold coordinated Ag, hole producing sites with a lower defect formation energy than the 4-fold coordinated one. Our calculation demonstrates that the advantage from lower coordination number of the Ag atom in KAg11(VO4)4 can be offset by the change in the range of Ag chemical potential in which synthesis is allowed due to the oxide phases that Ag forms with K and that energetically compete with KAg11(VO4)4. [ABSTRACT FROM AUTHOR]

The model GW method [F. Gygi and A. Baldereschi, Phys. Rev. Lett. 62, 2160 (1989)] is an efficient simplification to the standard GW approximation which uses model dielectric function to describe the long range Coulomb interactions in semiconductors. In this work, the model GW method is used to calculate the quasiparticle band structures of MnO, FeO, CoO, and NiO. All four late transition metal monoxides are predicted to be insulators. The band gaps, magnetic moments, and quasiparticle spectra are in good agreement with the experiments, except for the satellite structures which are missing in the density of states because the model GW self-energy is static. The high accuracy of model GW is due to the usage of the accurate dielectric constants in the construction of the model dielectric functions which ensures the correct asymptotic behavior of the long range Coulomb interactions. Besides, we find that the transition metal 4s states are irrelevant to the formation of the band gaps, which supports the local approaches and the experimental interpretations of the band gaps by photoemission and electron energy loss spectroscopy, while contradicts the recent calculations by hybrid functionals, exact exchange, and one shot GW approximations. [ABSTRACT FROM AUTHOR]

The high-temperature electrical conductivity and thermopower of several compounds in the In2O3(ZnO)k system (k=3, 5, 7, and 9) were measured, and the band structures of the k=1, 2, and 3 structures were predicted based on first-principles calculations. These phases exhibit highly dispersed conduction bands consistent with transparent conducting oxide behavior. Jonker plots (Seebeck coefficient versus natural logarithm of conductivity) were used to obtain the product of the density of states and mobility for these phases, which were related to the maximum achievable power factor (thermopower squared times conductivity) for each phase by Ioffe analysis (maximum power factor versus Jonker plot intercept). With the exception of the k=9 phase, all other phases were found to have maximum predicted power factors comparable to other thermoelectric oxides if suitably doped. [ABSTRACT FROM AUTHOR]

Improved conductivity has been achieved by controllable substitution of an ultraviolet electronic conductor. The transparent conducting oxide system, H-doped Ca12Al(14-x)SixO(33+x/2) with x=0-4, exhibits a conductivity strongly dependent on the substitution level. Four-point direct current conductivity increases with x from 0.15 to 0.61 S/cm at room temperature. The observed conductivity behavior is consistent with the predictions of our first principles density functional calculations for the Si-substituted system with x=0, 2, and 4. Furthermore, the Seebeck coefficient is composition dependent suggesting the existence of an activated mobility associated with small polaron conduction. [ABSTRACT FROM AUTHOR]

A tunable conductivity has been achieved by controllable substitution of an ultraviolet light activated electronic conductor. The transparent conducting oxide system H-doped Ca12-xMgxAl14O33 (x=0, 0.1, 0.3, 0.5, 0.8, 1.0) presents a conductivity that is strongly dependent on the substitution level and temperature. Four-point dc-conductivity decreases with x from 0.26 S/cm (x=0d to 0.106 S/cm sx=1) at room temperature. At each composition the conductivity increases sreversibly with temperatured until a decomposition temperature is reached; above this value, the conductivity drops dramatically due to hydrogen recombination and loss. The observed conductivity behavior is consistent with the predictions of our first principles density functional calculations for the Mg-substituted system with x=0, 1, and 2. The Seebeck coefficient is essentially composition and temperature independent, the later suggesting the existence of an activated mobility associated with small polaron conduction. The optical gap measured remains constant near 2.6 eV while transparency increases with the substitution level, concomitant with a decrease in carrier content. [ABSTRACT FROM AUTHOR]

The Lewis acidic liquid EMIMBr-Al[Cl.sub.3] (EMIM = 1-ethyl-3-methylimidazolium) has provided a synthetic route to the semiconducting layered metal chalcogenides halide [[Bi.sub.2][Te.sub.2]Br](Al[Cl.sub.4]) and its Sb analogue. [[Bi.sub.2][Te.sub.2]Br](Al[Cl.sub.4]) is shown to be a direct band gap, strongly anisotropic semiconductor and has cationic infinite layers of [[[Bi.sub.2][Te.sub.2]Br].sup.+] and [[Al[Cl.sub.4].sup.-] anions inserted between the layers.

Identification and single-crystal x-ray diffraction studies of AAs[Se.sub.2] (where A = Li, Na) as a new class of polar direct-band gap semiconductors is described. The theoretical studies which confirmed with the experimental results indicated the [gamma]-NaAs[Se.sub.2] to have the highest static SHG coefficient of 337.9 pm/V, among materials with band gaps larger than 1.0 eV.

The soluble inorganic polymer [K.sub.4][P.sub.8][Te.sub.4] which give solutions that exhibit white emission upon 355 nm laser irradiation and features infinite chains of [[P.sub.8][Te.sub.4.sup.4-]] with covalent P-Te bonding that exhibit reversible crystal-glass phase-change behavior is reported. Speciation of [K.sub.4][P.sub.8][Te.sub.4] in solution explored with [super 31]P solution-state NMR spectroscopy, electrospray ionization mass spectrometry, and PDF analysis revealed exfoliation of [[P.sub.8][Te.sub.4.sub.4-]] chains followed by rearrangement into molecular species.

The iron arsenide Ca[Fe.sub.4][As.sub.3] has featured a three-dimensional network derived from intergrown [Fe.sub.2][As.sub.2] layers and Ca ions in channels. Complex magnetic interactions between Fe atoms have provided unexpected transitions and novel direction-dependent magnetic behavior.

The [Cs.sub.5]Bi[P.sub.4][Se.sub.12] fibers are transparent in the near- and mid-infrared ranges and have displayed a nonlinear optical second harmonic generation response at 1 [micro]m that is approximately twice that of the benchmark material AgGa[Se.sub.2]. The full-potential linearized augmented plane wave (FLAPW) method has shown that the band gap has increased from its local density approximation (LDA) spin-orbit coupling value of 1.15 eV to the higher value of 2.0 eV when the screened-exchange LDA method is invoked.

An investigation on the dopant ion size and electronic structure effects on the charge transport properties and electronic band structures of CdO-based transparent conducting oxides (TCOs) is conducted. The results reveal that dopant ion size and electronic configuration have substantial influence on the CdO crystal and band structure, especially on the energetic position and width of the highly dispersed conduction band.

The highly conductive and transparent CSO thin films are grown on glass and single-crystal MgO(100) substrates at 400 degree Celsius by an MOCVD process. The XRD data reveal that all of these features as-deposited Sc-doped CdO (CSO) films are phase-pure and highly crystalline with features assignable are found to contract with the introduction of Sc(super 3+) in agreement with the full-potential linear augmented plane wave (FLAPW) calculations.

First-principles of the bcc Fe(001)/TiC(001) interface with TiC in the NaCl structure, predict their magnetism and adhesion strength. The interface Fe shows substantially reduced magnetism, while the second Fe layer has the bulk magnetic moment.

The heavy metal selenophosphate, Pb2P2Se6, is a promising new material for cost-effective X-ray/γ-ray detection. Crystal boules of Pb2P2Se6 up to 25 mm in length and 15 mm in diameter are grown by a vertical Bridgman method. They are cut and processed into size-appropriate wafers for physical, photo-transport property studies, as well as γ-ray detector testing. The material is a semiconductor with an indirect bandgap of 1.88 eV and has electrical resistivity in the range of 1 × 1010 Ω cm. Pb2P2Se6 single crystal samples display a significant photoconductivity response to optical, X-ray, and γ-ray radiation. When tested with a 57Co γ-ray source, Pb2P2Se6 crystals show spectroscopic response and several generated pulse height spectra resolving the 122.1 and 136.5 keV 57Co radiation. The mobility-lifetime product of Pb2P2Se6 is estimated to be ≈3.5 × 10−5 cm2 V−1 for electron carriers. The Pb2P2Se6 compound melts congruently at 812 °C and has robust chemical/physical properties that promise low cost bulk production and detector development. [ABSTRACT FROM AUTHOR]

EuIr4In2Ge4 is a new intermetallic semiconductor that adopts a non-centrosymmetric structure in the tetragonal ${I\bar 42m}$ space group with unit cell parameters a=6.9016(5) Å and c=8.7153(9) Å. The compound features an indirect optical band gap Eg=0.26(2) eV, and electronic-structure calculations show that the energy gap originates primarily from hybridization of the Ir 5d orbitals, with small contributions from the Ge 4p and In 5p orbitals. The strong spin-orbit coupling arising from the Ir atoms, and the lack of inversion symmetry leads to significant spin splitting, which is described by the Dresselhaus term, at both the conduction- and valence-band edges. The magnetic Eu2+ ions present in the structure, which do not play a role in gap formation, order antiferromagnetically at 2.5 K. [ABSTRACT FROM AUTHOR]

EuIr4In2Ge4 is a new intermetallic semiconductor that adopts a non-centrosymmetric structure in the tetragonal I̅ 42m space group with unit cell parameters a=6.9016(5) Å and c=8.7153(9) Å. The compound features an indirect optical band gap Eg=0.26(2) eV, and electronic-structure calculations show that the energy gap originates primarily from hybridization of the Ir 5d orbitals, with small contributions from the Ge 4p and In 5p orbitals. The strong spin-orbit coupling arising from the Ir atoms, and the lack of inversion symmetry leads to significant spin splitting, which is described by the Dresselhaus term, at both the conduction- and valence-band edges. The magnetic Eu2+ ions present in the structure, which do not play a role in gap formation, order antiferromagnetically at 2.5 K. [ABSTRACT FROM AUTHOR]

In diverse classes of organic optoelectronic devices, controlling charge injection, extraction, and blocking across organic semiconductor-inorganic electrode interfaces is crucial for enhancing quantum efficiency and output voltage. To this end, the strategy of inserting engineered interfacial layers (IFLs) between electrical contacts and organic semiconductors has significantly advanced organic light-emitting diode and organic thin film transistor performance. For organic photovoltaic (OPV) devices, an electronically flexible IFL design strategy to incrementally tune energy level matching between the inorganic electrode system and the organic photoactive components without varying the surface chemistry would permit OPV cells to adapt to ever-changing generations of photoactive materials. Here we report the implementation of chemically/environmentally robust, low-temperature solution-processed amorphous transparent semiconducting oxide alloys, In-Ga-O and Ga-Zn-Sn-O, as IFLs for inverted OPVs. Continuous variation of the IFL compositions tunes the conduction band minima over a broad range, affording optimized OPV power conversion efficiencies for multiple classes of organic active layer materials and establishing clear correlations between IFL/photoactive layer energetics and device performance. [ABSTRACT FROM AUTHOR]

Large plate crystals of LaPtGe2 have been grown by using an inert indium metal flux. This compound crystallizes in the CeNiSi2-type structure (orthorhombic space group Cmcm) with lattice parameters a = 4.3770(9) Å, b = 17.186(3) Å, and c = 4.3942(9) Å. The structure of LaPtGe2 is a three-dimensional framework with alternating PbO-type layers of PtGe and infinite Ge chains, separated by La atoms. Electrical resistivity and Hall effect measurements characterize LaPtGe2 as a metal with holes that act as the charge carriers. Strong temperature dependence of the Hall coefficient and a violation of Kohler's rule (from magnetoresistance data) both indicate possible multiband effects. The electronic structure calculations suggest the metallic nature of LaPtGe2 and show that the strongest bonding exists between Pt and Ge within the PbO-type layers. [ABSTRACT FROM AUTHOR]