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Low-temperature soft chemical synthesis routes to transition-metal nitrides are of interest as an alternative to conventional high-temperature ammonolysis reactions involving large volumes of chemotoxic NH3 gas. One such method is the reaction between metal oxides and NaNH2 at ca. 200 °C to yield the counterpart nitrides; however, there remains uncertainty regarding the reaction mechanism and product phase assemblage (in particular, noncrystalline components). Here, we extend the chemical tool box and mechanistic understanding of such reactions, demonstrating the nitridation of Fe3O4 by reaction with NaNH2 at 170–190 °C, via a pseudomorphic reaction. The more reduced Fe3O4 precursor enabled nitride formation at lower temperatures than the previously reported equivalent reaction with Fe2O3. The product phase assemblage, characterized by X-ray diffraction, thermogravimetric analysis, and 57Fe Mössbauer spectroscopy, comprised 49–59 mol % ε-Fe2+xN, accompanied by 29–39 mol % FeO1–xNx and 8–14 mol % γ″-FeN. The oxynitride phase was apparently noncrystalline in the recovered product but could be crystallized by heating at 180 °C. Although synthesis of transition-metal nitrides is achieved by reaction of the counterpart oxide with NaNH2, it is evident from this investigation that the product phase assemblage may be complex, which could prove a limitation if the objective is to produce a single-phase product with well-defined electrical, magnetic, or other physical properties for applications. However, the significant yield of the FeO1–xNx oxynitride phase identified in this study opens the possibility for the synthesis of metastable oxynitride phases in high yield, by reaction of a metal oxide substrate with NaNH2, with either careful control of H2O concentration in the system or postsynthetic hydrolysis and crystallization.

Eu^[2+]-doped β-SiAlON (Si_[6-z]AlzOzN_[8-z]) phosphors with 1 ≤ z ≤ 4 were synthesized by gas pressure sintering. The emission spectra exhibit two broad bands with maxima at about 415 nm (violet) and 540 nm (green) under ultraviolet excitation. The green emission is dominant at z ≤ 2, while the violet emission becomes dominant at z > 2. The combination of two emission bands in a compound could lead to a white emission in Eu^[2+]-doped β-SiAlON with 2 < z ≤ 3.

A method for analyzing molecular motion of a branched long chain polymer wherein the position coordinate, the orientation vector, the number of monomers in the constituent elements of a tube and counterpart tube constituent elements forming entanglement are time-developed over a unit time defined by expression 7 according to the Langevin equation defined by expression 1 on the basis of the reptation theory with regard to an inter-tube constituent element constituting each polymer produced by coarse-graining the polymers of a mixture of the branched long chain polymer material to be analyzed according to the entanglement molecular weight (step 201), the number of monomers in the constituent element of the tube is time-development according to expression 5 (step 202), the number n of monomers in the constituent element of the tube at each end of a polymer is monitored, the constituent element of the counterpart tube forming entanglement is altered according to expression 8, and geometrical position exchange is caused to take place between the entanglement and a branch point by the number of constituent element of the tube at a branch part belonging to the branch point

A method for analyzing molecular motion of a copolymer comprising a step for time-developing the constitutional element of an associated tube forming positional coordinates, an orientation vector, number of monomers in the constitutional elements of a tube and an entanglement over a unit time defined by expression 7 according to Langevin equation defined by expression 1 with regard to an inter-tube constitutional element constituting each polymer produced by coarse-graining the polymer of a mixture of a copolymer material to be analyzed based on the inter-entanglement molecular weight based on reptation theory (step 201), and a step for time-developing the number of monomers in the constitutional element of tube according to expression 5 (step 202) wherein the number n of monomers in the constitutional element of tube at each end of a polymer is monitored, the constitutional element of an associated tube forming an entanglement is altered according to expression 8, and geometrical positional exchange is caused to take place between the entanglement and a branch point by the number of constitutional elements of a tube at a branch part belonging to the branch point.

In a method of analyzing the molecular motion of a mixture comprising different polymer materials, the polymers of the mixture comprising different polymer materials to be analyzed are roughly visualized depending on the molecular weights among tangling points according to the reptation theory. Based on the intertube factor constituting each polymer thus formed, the position coordinate, the alignment vector, the number of monomers in the tube factor and the tube factor of the counterpart forming the tangling are time developed per the unit time as defined by the formula 7 in accordance with Langevin formula defined by the formula 1 (step 201). Then the number of monomers in the tube factor is time developed in accordance with the formula 5 (step 202) and the number (n) of monomers in the tube factor at each terminus of the polymer is monitored. In accordance with the formula 8, the tube factor of the counterpart forming the tangling is altered.

A method for analyzing the molecular motion of a polymer compound which comprises forming, according to the reptation theory, tube−constituting elements composing each polymer molecule through a macroscopic operation based on an entanglement molecular weight with respect to the polymer molecule of the polymer compound, subjecting the position coordinates and orientation vectors of the tube−constituting elements, the numbers of monomers in the tube−constituting elements, and the tube−constituting elements playing opposite at the formation of entanglement, to time development according to Langevin equation over the unit time defined by the formula (4) (step 201), subjecting the numbers of monomers in the tube−constituting elements to time development according to equation (2) (step 202), monitoring the number (n) of monomers in the tube−constituting element positioning in each terminal of the polymer molecule, and changing the tube−constituting elements playing opposite at the formation of entanglement according to the formula (5).

Here we report the magnetic properties of the layered cobalt oxide system, LixCoO2, in the whole range of Li composition, 0 = 0.40), on the other hand, various phase transitions are observed. For x = 0.40, a susceptibility hump is seen at 30 K, suggesting the onset of static AF order. A magnetic jump, which is likely to be triggered by charge ordering, is clearly observed at Tt = 175 K in samples with x = 0.50 (= 1/2) and 0.67 (= 2/3), while only a tiny kink appears at T = 210 K in the sample with an intermediate Li composition, x = 0.60. Thus, the phase diagram of the LixCoO2 system is complex, and the electronic properties are sensitively influenced by the Li content (x)., Comment: 29 pages, 1 table, 9 figures

The primitive chain network model of entangled polymers, where primitive chains and entanglements are assigned in real 3-D space, is a possible step in the multi-scale path from atomistic simulations to macroscopic constitutive equations. In any coarse-grained model of a polymeric system, however, determination of the basic parameters is a crucial step. By fitting the linear viscoelastic response of several melts of monodisperse linear polymers taken from the literature, we here determine the corresponding basic parameters of the primitive chain network model. We concentrate in particular on the value of the mean molar mass between entanglements, and on how such a mass is related to plateau modulus from our simulations. We consistently find values that fall around 60% of the entanglement molecular weight as obtained from Ferry's definition, and we envisage that such a result is due to Brownian fluctuations of the entanglement nodes.