Materials Literature
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A model of nonradiative transitions in spin-crossover molecules is developed. The model takes into account linear and quadratic terms of electron-vibrational interaction. The frequency effect is shown to arise from the quadratic term of this interaction. With account of the frequency effect analytical expressions are…
The low temperature (6 K) EPR spectrum of Cu 2+ in K 2 Zn(SO 4 ) 2 ·6H 2 O is characteristic for the ground state a | x 2 - y 2 ⟩- b | z 2 ⟩ with essentially the | x 2 - y 2 ⟩ state and 4.5% admixture of the | z 2 ⟩ state due to the zero-point motions. Temperature variations of the g and A parameters are characteristi…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTChemical Shielding Tensors for a Silicon−Carbon Double BondJarrod J. Buffy, Robert West, Michael Bendikov, and Yitzhak ApeloigView Author Information Department of Chemistry, University of Wisconsin-Madison Madison, Wisconsin 53706 Department of Chemistry and the Lise…
We report dc and ac magnetization of the newly discovered Cd-Mg-RE quasicrystals (RE = Gd, Tb, Dy, Ho, Er, Tm and Yb). For all the RE atoms except Yb, the temperature dependence of the dc magnetization obeys the Curie-Weiss law at higher temperatures, T >50 K. Estimated effective moments indicate that these atoms are…
The preparation and crystal structures of two oxalato-bridged FeII-FeIII mixed-valence compounds, [FeII(bpm)3]2[FeIII2(ox)5].8H2O (1) and FeII(bpm)3Na(H2O)2FeIII(ox)(3).4H2O (2) (bpm = 2,2'-bipyrimidine; ox = oxalate dianion) are reported here. Complex 1 crystallizes in the triclinic system, space group P1, with a = 1…
The nature of the attractive electron-electron interaction, leading to the formation of Cooper pairs in unconventional superconductors, has still to be fully understood and is subject to intensive research. Here we show that the sequence spin-Peierls, antiferromagnetism, superconductivity observed in (TMTTF) 2 PF 6 un…
Core-level Mn and Co 2p x-ray photoelectron spectroscopic studies give evidence for different spin states of Mn and Co in the two different phases of the ferromagnetic compound LaMn 0.5 Co 0.5 O 3 . Ferromagnetism in the high- T c ( T c ≈230 K) phase of the compound arises from Mn 3+ -O-Mn 3+ superexchange interaction…
Excited state absorption spectra from the 4f 2 levels of Pr 3+ in YPO 4 to 4f5d were measured at 293 and 77 K using a pulsed pump-probe technique. The spectra from the 1 D 2 manifold were recorded by employing a continuous wave probe, whilst those from the 3 P J - 1 I 6 states were recorded by using for the first time…
We have investigated transport and magnetic properties of a series of double-perovskite alloys in the system Sr 2 FeMo x W 1- x O 6 . These compounds exhibit a metal-insulator transition as a function of doping, x . The compounds with x in the range 1.0⩾ x ⩾0.3 show metallic behaviour in the resistivity while compound…
The construction of two-dimensional (2D) copper halide networks within a variety of perovskite hosts by a low-temperature topochemical method is demonstrated. Ion exchange between some layered perovskite oxides of the type A'[An - 1(M,M')nO3n + 1] (A' = alkali metal, H, NH4; A = alkaline earth, rare earth, or Bi; M,M'…
The synthesis and characterization of (Bu4N)4[S2W18O62].1.23MeCN.0.27H2O are reported. It crystallizes in the monoclinic space group C2/c with a = 22.389(6) A, b = 22.104(3) A, c = 25.505(5) A, beta = 95.690(15) degrees, V = 12560(5) A3, and Z = 4. The anion exists as the gamma* isomer, the second example of this isom…
A process for the large-scale production of 4-hydroxyvalerate (4HV)-containing biopolyesters with a new monomer composition was developed by means of high-cell-density cultivation applying recombinant strains of Pseudomonas putida and Ralstonia eutropha, harboring the PHA-biosynthesis genes phaC and phaE of Thiocapsa…
An unusual field-dependent slow magnetic relaxation and two distinct transitions were observed in a family of rare-earth--transition-metal complexes [Ln (bipy) $({\mathrm{H}}_{2}\mathrm{O}{)}_{4} M(\mathrm{CN}{)}_{6}] \ensuremath{\cdot}1.5$ (bipy) $\ensuremath{\cdot}4{\mathrm{H}}_{2}\mathrm{O}$ $(\mathrm{b}\mathrm{i}\…
We compare the results of measurements of the magnetic susceptibility Chi(T), the linear coefficient of specific heat Gamma(T)=C(T)/T and 4f occupation number nf(T) for the intermediate valence compounds YbXCu4 (X = Ag, Cd, In, Mg, Tl, Zn) to the predictions of the Anderson impurity model, calculated in the non-crossi…
The Landau-Lifshitz (L-L) equation describing the time dependence of the magnetisation vector is numerically integrated fully without any simplifying assumptions in the time domain and the magnetisation time series obtained is Fourier transformed (FFT) to yield the permeability spectrum up to 10 GHz. The non linear re…
We studied the dynamical properties of Au using our previously developed tight-binding method. Phonon-dispersion and density-of-states curves at T=0 K were determined by computing the dynamical-matrix using a supercell approach. In addition, we performed molecular-dynamics simulations at various temperatures to obtain…
Titanium-substituted mesoporous SBA-15 molecular sieve has been successfully prepared at 373 K by direct synthesis under microwave−hydrothermal conditions within about 2 h. By means of X-ray diffraction, nitrogen adsorption, infrared, UV−vis diffuse reflectance, and Raman spectroscopies, a successful isomorphous subst…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTConducting Polyaniline Nanotubes by Template-Free PolymerizationHongjin Qiu, Meixiang Wan, Barry Matthews, and Liming DaiView Author Information Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Bei…
The photoelectrochemical characteristics of highly transparent nanoporous WO 3 films are described. The photocurrent versus excitation wavelength spectra of these photoelectrodes exhibit a maximum close to 400 nm and a significant photoresponse to the blue part of the visible spectrum. The observed conversion efficien…
The effect of phospho- l -serine in supersaturated solutions of calcium phosphate was investigated at plethostatic conditions. Phospho- l -serine inhibited the crystal growth of hydroxyapatite {Ca 5 OH(PO 4 ) 3, HAP} by blocking the crystal growth centers through adsorption. Complete inhibition was attained with a pho…