Materials Literature
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The two main effects underlying the magnetic shape memory effect in Ni2MnGa are martensitic transformations and magnetic anisotropy energies. Both issues are addressed here with first-principles calculations. First, we examine how the tetragonality in the martensitic phase varies with the composition. Then, the actual…
Differential scanning calorimetry and Raman spectroscopy measurements have been performed to investigate the β-cubic (c) phase transition of the compositionally homogeneous ZrO2-22 mol % ScO1.5 solid solution. The enthalpy of transition (1.11 kJ/mol of cation) and thermal hysteresis between β- and c-phases were smalle…
The phase diagram of hexagonal HoMnO3 in the magnetic-field/temperature plane is investigated by second harmonic generation (SHG). Four different magnetic phases of the frustrated Mn sublattice are identified on the basis of the selection rules for SHG. In-plane or interplane reordering of Mn spins at the phase bounda…
Investigations were made into the effect of small additions of Ni, Mo, Sn, as well as larger additions of Al on the magnetostriction of single crystal Fe100−xGax alloys (x≅13). The Fe–Ga and Fe–Al systems are seemingly unique among the Fe-based alloys in having very large magnetostrictions in spite of Ga and Al being…
The sputter deposited NiZn ferrite thin films were studied as a function of annealing temperature. The magnetization showed a monotonic increase with increasing annealing temperature. The coercivity shows a minimum at annealing temperature of 400 °C and shows a value of 14 Oe. Transmission electron microscopy study in…
To gain insight into the thermodynamics of protein denaturation, the complex heat capacity, C p * (= C p ‘ − iC p ‘ ‘) of lysozyme−water system has been measured at pH 2.5 in the 293−368 K range by using temperature-modulated scanning calorimetry (TMSC), a technique in which the thermally reversible enthalpy changes a…
MnBi forms peritectically at ∼450 °C. Preparation of MnBi employing conventional techniques such as arc melting and induction melting results in the segregation of manganese. In order to avoid this segregation, we followed the procedure recommended by Guo et al. [X. Guo, A. Zaluska, Z. Altounian, and J. O. Strom-Olsen…
Small-angle neutron scattering (SANS) has been used to measure the chain dimensions of syndiotactic polypropylene ( s -PP) in the melt, using mixtures of 1 H- and 2 D-labeled molecules. This leads to a segment length 7.6 Å normalized to a four-carbon repeat unit, which is in excellent agreement with a prediction based…
The conducting polymers such as polyaniline, polypyrrole and polythiophene were functionalized with copper phthalocyanine using chemical oxidation method. The obtained polymers viz. PANI-CuPc, PPy-CuPc and PT-CuPc were studied as chemical sensors by their response characteristics after exposure to various chemical vap…
Scanning tunneling microscopy and core level photoelectron spectroscopy measurements have been used to investigate the morphology of ZnO(0001 macro)-O, and its reactivity with carbon monoxide and carbon dioxide, as a function of surface preparation. Real space images of the surface indicate that increasing the substra…
Steels with high Si content (up to 6.5% Si) are excellent soft magnetic materials, however, as the Si content is increased, the material becomes extremely brittle and it is very difficult to produce thin sheet by conventional rolling. An alternative production route has been developed through hot dipping in a high Si-…
High purity MnBi low temperature phase has been prepared and analyzed using magnetic measurements and neutron diffraction. The low-temperature phase of the MnBi alloy has a coercivity μ0iHc of 2.0 T at 400 K, and exhibits a positive temperature coefficient from 0 to at least 400 K. The neutron data refinement indicate…
Using oxalate as a stabilizing agent, stable colloidal solutions of platinum nanoparticles of different shape distributions were prepared by reducing K 2 [Pt(C 2 O 4 ) 2 ], K 2 PtCl 6, or K 2 PtCl 4 with hydrogen. The mean diameters of the Pt nanoparticles prepared from these precursors are 6.5, 3.5, and 7.9 nm, respe…
The influence of monatomic steps on the oxidation of adsorbed CO is examined using potentiodynamic and galvanostatic experiments. Galvanostatic experiments allow a better determination of the lowest possible oxidation potential than cyclic voltammetry. By comparing results on Pt(111), Pt(665), Pt(332), and Pt(755), we…
We report here a new understanding of the mechanisms involved in the sonoelectrochemical synthesis of nanoparticles. Our results indicate that, in addition to the deposition-break processes, a suspended electrode that is formed by the ultrasonic wave has a major effect on the particles’ properties. This new understand…
The size effects on the crystal structure and phase transitions have been investigated for BaTiO 3 fine particles of 700, 400, 300 and 100 nm size, by means of powder diffraction using synchrotron radiation (SR) high-energy X-rays. The Rietveld refinement reveals that the BaTiO 3 fine particles consist of tetragonal a…
The surfactant-free synthesis of poly(methyl methacrylate)−silica nanocomposite particles has been achieved in aqueous alcoholic media at ambient temperature without the use of auxiliary comonomers. Stable colloidal dispersions with reasonably narrow size distributions can be obtained with silica contents of up to 58%…
Inorganic−organic hybrid polymers were prepared by radical polymerization of methacrylic acid or methyl methacrylate with 0.5−2 mol % of the (meth)acrylate-substituted oxotitanium clusters Ti 6 O 4 (OEt) 8 (OMc) 8 (OMc = methacrylate), Ti 6 O 4 (OPr) 8 (OAcr) 8 (OAcr = acrylate), and the new clusters Ti 4 O 2 (OPr i )…
Zinc-blende CrAs/GaAs multilayers were grown by molecular beam epitaxy. It was certified that each CrAs layer maintains an epitaxial relationship with the zinc-blende GaAs structure judging from the reflection high-energy electron diffraction observation. The film contains thicker zinc- blende CrAs layers in total tha…
Co–Ti substituted M-type hexagonal barium ferrite nanoparticles BaFe12−2xCoxTixO19 (0⩽x⩽1.0) have been prepared by a sol-gel method. Magnetic and structural properties of the powders were characterized with a Mössbauer spectroscopy, vibrating sample magnetometer, x-ray diffraction (XRD), thermogravimetry (TG), and dif…