Materials Literature
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A general chemical method has been developed to prepare semiconductor hollow microspheres with various electronic bandgaps (see SEM image), as well as a number of core/shell structures. These hollow structures have potential applications in the fields of optoelectronic technology, photovoltaic devices, photonic bandga…
By using transmission electron microscopy (TEM), the chirality of novel mesoporous materials has been studied. In addition, a computer simulation that uses a simple structural model was employed. The existence of chiral channels inside a tubelike material was confirmed by the observation of fringes along the length of…
A scheme of nanoscale lasers based on the so-called carbon peapods is examined in details. Since there is considerable cylindrical empty space in the middle of a single-wall carbon nanotube (SWCNT), it can serve as a laser resonant cavity that consists of two highly reflecting, alignment “mirrors” separated by some di…
Reversible 300 K ferromagnetic ordering in a diluted magnetic semiconductor, Co2+:ZnO, is achieved by lattice incorporation and removal of the native n-type defect, interstitial Zn, resulting in “off” and “on” states (Figure, red triangles and blue circles). Spectroscopic and magnetic data implicate a double-exchange…
The spin-reorientation transition of layered perovskite oxide CaNdFeO4has been investigated through powder x-ray and neutron diffraction, magnetic susceptibility, specific heat and 57Fe M?ssbauer spectrum measurements. This oxide presents orthorhombic symmetry (space group:?Bmab)?with lattice parameters at room temper…
CdSe quantum dots have been produced in an amorphous GeS 2 thin film matrix by alternating thermal evaporation in vacuum and deposition of several CdSe and GeS 2 layers, with the thickness of the latter being, typically, 20 times larger than that of the former. Raman scattering spectra of these films have been measure…
Using a laser monitoring observation technique, solid−liquid equilibria in the systems benzoic acid + p -toluic acid + chloroform at 303.15 K, benzoic acid + p -toluic acid + acetic acid at 343.15 K, and terephthalic acid + isophthalic acid + N,N -dimethylformamide at 343.15 K have been investigated. The solid−liquid…
In this work, we examine the phase stability of both uncoated and alumina-coated zirconia nanoparticles using in-situ X-ray diffraction. By tracking structural changes in these particles, we seek to understand how changing interfacial bonding affects the kinetics of amorphous zirconia crystallization and the kinetics…
The colossal magnetoresistance (CMR) effect in perovskite manganites is a magnetic-field-induced transition from a paramagnetic insulating (PI) to a ferromagnetic metallic state. The large electrical resistivity of the PI state lies at the heart of the CMR effect. This enhanced resistivity stems, in part, from strong…
An assumed B 2 CN crystal system containing seven possible diamond-structured configurations in boron-carbonitride B–C–N compounds has been studied by using an ab initio pseudopotential density functional method. After structural relaxation, the lattice constant, bulk modulus and shear modulus, and electronic band str…
Nickel formate serves as an ideal catalyst precursor for surface-bound thermal and plasma-enhanced CVD growth of carbon nanotubes. As the method of deposition of the Ni catalyst is solution-based, it benefits from a low-cost, large-area growth, ease of operation and suitability for coating substrates with complex shap…
Using NMR inversion recovery experiments and XPLOR distance restraint calculations, we recently deduced the structure of ferriprotoporphyrin IX (FPIX) heme mu oxo dimer-antimalarial drug complexes for chloroquine (CQ), quinine (QN), and quinidine (QD) at atomic resolution [A. Leed et al., Biochemistry 2002, 41, 10245-…
We report on the effect of Mn site substitution of Al on the structural, magnetic and transport properties of charge ordered Pr 0.5 Ca 0.5 MnO 3 . This substitution introduces non-magnetic impurities in the Mn–O–Mn network, causes the Mn 3+ /Mn 4+ ratio to deviate away from unity and is seen to predominantly replace M…
Li+ motion in quartz and β-eucryptite (LiAlSiO4) is investigated by dielectric spectroscopy and classical simulations. Simulations are performed using a combination of traditional energy-minimization (using the GULP code) and a mechanical approach derived from Rigid Unit modelling, implemented in the GASP code. Compar…
Lines of formation and decomposition of the hcp (ε) molybdenum deuteride in the T–P phase diagram of the Mo–D system are constructed via the measurement of isotherms of the electrical resistance of molybdenum in a deuterium atmosphere at temperatures up to 550 °C and pressures up to 6 GPa. The diagram is compared to t…
An in situ Raman spectroscopic study was conducted to explore the pressure-induced phase transformation of Sr2CaWO6 to pressures of 50.8 GPa and room temperature. Group theory yields 24 Raman active modes for Sr2CaWO6, of which 17 are observed at ambient conditions. Upon elevation of pressure to 3.2 GPa, the results s…
The series of the SrTi(1-x)Co(x)O(3-delta) polycrystalline samples has been prepared via solid-state reaction in air. The structural study shows that a solid solution exists for all compositions, such as 0 < or = x < or = 0.9, which discards the presence of ferromagnetic and metallic cobalt clusters for the low level…
At temperatures below the metal–insulator transition of La 1− x Sr x MnO 3 with 0.1 < x < 0.15, a peculiar ferromagnetic and insulating phase is observed which has been intensively discussed over the last few years. We present a detailed investigation of this phase by means of resonant and high energy x-ray scattering…
We investigated the temperature-dependent optical absorption spectra of LaMnO 3 and NdMnO 3 epitaxial thin films. We found that both spectra have strong absorption features around 2 eV, and that the 2 eV peak of LaMnO 3 has a weak temperature dependence. As the La ions are replaced with Nd ions, the spectral weight of…
Colossal magneto-resistance manganites are characterized by a complex interplay of charge, spin, orbital and lattice degrees of freedom. Formulating microscopic models for these compounds aims at meeting two conflicting objectives: sufficient simplification without excessive restrictions on the phase space. We give a…