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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.

AAsSe2 (A = Li, Na) have been identified as a new class of polar direct-band gap semiconductors. These I-V-VI2 ternary alkali-metal chalcoarsenates have infinite single chains of (1/∞)[AsQ2-] derived from corner-sharing pyramidal AsQ3 units with stereochemically active lone pairs of electrons on arsenic. The conformations and packing of the chains depend on the structure-directing alkali metals. This results in at least four different structural types for the Li1-xNaxAsSe2 stoichoimetry (α-LiAsSe2, β-LiAsSe2, γ-NaAsSe2, and δ-NaAsSe2). Single-crystal X-ray diffraction studies showed an average cubic NaCl-type structure for α-LiAsSe2, which was further demonstrated to be locally distorted by pair distribution function (PDF) analysis. The β and γ forms have polar structures built of different (1/∞)[AsSe2] chain conformations, whereas the δ form has nonpolar packing. A wide range of direct band gaps are observed, depending on composition: namely, 1.11 eV for α-LiAsSe2, 1.60 eV for LiAsS2, 1.75 eV for γ-NaAsSe2, 2.23 eV for NaAsS2. The AAsQ2 materials are soluble in common solvents such as methanol, which makes them promising candidates for solution processing. Band structure calculations performed with the highly precise screened- exchange sX-LDA FLAPW method confirm the direct-gap nature and agree well with experiment. The polar γ-NaAsSe2 shows very large nonlinear optical (NLO) second harmonic generation (SHG) response in the wavelength range of 600-950 nm. The theoretical studies confirm the experimental results and show that γ-NaAsSe2 has the highest static SHG coefficient known to date, 337.9 pmN, among materials with band gaps larger than 1.0 eV. [ABSTRACT FROM AUTHOR]

We describe the inorganic polymer K4P8Te4 which is soluble, giving solutions that exhibit white emission upon 355 nm laser irradiation. An indirect band gap semiconductor (Eg ≈ 1.4 eV), K4P8Te4 crystallizes in the space group P21/m, with a = 6.946(1) Å, b = 6.555(1) Å, c = 9.955(2) Å, and β = 90.420(3)° at 173(2) K. The compound features infinite chains of [P8Te44-] with covalent P-Te bonding and exhibits reversible crystal-glass phase-change behavior. When deposited from solution, the material forms highly crystalline K4P8Te4 nanospheres. The thermal analysis, FT-IR, UV-vis diffuse reflectance, 31P magic angle spinning solid-state NMR spectroscopy, and pair distribution function (PDF) analysis for the crystal and glass forms and ab initio electronic structure calculations by the screened-exchange local density function approximation are also reported. Speciation of K4P8Te4 in solution studied with 31P solution-state NMR spectroscopy, electrospray ionization mass spectrometry, and PDF analysis indicate exfoliation of [P8Te44-] chains followed by rearrangement into molecular species. [ABSTRACT FROM AUTHOR]

The Cs5BiP4Se12 salt grows naturally as nanowires that crystallize in the polar space group Pmc21, with a = 7.5357(2) Å, b = 13.7783(6) Å, C = 28.0807(8) Å, and Z = 4 at 293(2) K. The compound features octahedral [Bi(P2Se6)2]5 coordination complexes that stack via weak intermolecular SeߪSe interactions to form long, flexible fibers and nanowires. The Cs5BiP4Se12 fibers are transparent in the near- and mid-IR ranges and were found to exhibit a nonlinear optical second harmonic generation response at 1 μm that is approximately twice that of the benchmark material AgGaSe2. The material has a nearly direct band gap of 1.85 eV and melts congruently at 590 °C. Ab initio electronic structure calculations performed with the full-potential linearized augmented plane wave (FLAPW) method show that the band gap increases 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 and explain how the long nanowire nature of Cs5BiP4Se12 emerges. [ABSTRACT FROM AUTHOR]

The Lewis acidic ionic liquid EMIMBr-AlCl3 (EMIM = 1-ethyl-3-methylimidazolium) allows a novel synthetic route to the semiconducting layered metal chalcogenides halide [Bi2Te2Br]-(AlCl4) and its Sb analogue. [Bi2Te2Br](AlCl4) is a direct band gap, strongly anisotropic semiconductor and consists of cationic infinite layers of [Bi2Te2Br]+ and [AlCl4]- anions inserted between the layers. [ABSTRACT FROM AUTHOR]

The article presents the study on the cause of superconductivity in several types of compounds. A kind of metallic iron arsenide which is the CaFe4As3 was used. It is stated that the properties of CaFe4As3 need further study that includes the temperature-dependent neutron diffraction and the pressure on magnets.