Materials Literature
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A comprehensive review is given of recent advances in the study of metastable phases in rare-earth permanent magnets. The relations between the structures of the metastable and equilibrium phases and the transformations from the former to the latter are discussed. The formation of the phases is found to depend on the…
Neutron irradiation of the polygranular graphites used in reactor moderators results in an initial bulk shrinkage at low neutron fluence followed by expansion at higher neutron fluence. Recent work carried out to investigate the effects of simultaneous radiolytic oxidation on the dimensional-change behaviour of the Gi…
Thin films of yttrium sesquioxide, Y 2 O 3 , have been deposited on Si by ion beam sputtering at room temperature and 700 °C under an oxygen pressure of 4 × 10 -3 Pa or by oxygen ion beam assisted deposition. The stoichiometry of these films was analysed by Rutherford backscattering spectrometry. The thickness and ref…
Magnetization of compound La(Fe 0.98 Co 0.02 ) 11.7 Al 1.3 was measured carefully as functions of temperature and applied field around its Curie temperature of ~198 K. Magnetic entropy change |Δ S |, allowing estimation of the magnetocaloric effect (MCE), was determined based on thermodynamic Maxwell's relation. The a…
The growth of thin films from low-temperature plasmas plays an important role in many applications such as optical or wear-resistant layers or for the fabrication of electronic devices. Albeit of great importance, the underlying growth mechanisms responsible for film formation from low-temperature plasmas are not well…
Crystallization behavior of isotactic polypropylene (iPP) with extremely high isotacticity has been studied over a very wide range of crystallization temperature T c (145 °C ≤ T c ≤ 166 °C). Optical polarized microscopy observation reveals that morphologies obtained before and after T c = 157.0 °C are different in nat…
We report high-pressure liquid chromatography (HPLC) and transmission electron microscopy (TEM) studies of the size distributions of nanosize gold clusters dispersed in organic solvents. These metal clusters are synthesized in inverse micelles at room temperature, and those investigated range in diameter from 1 to 10…
Manganite multilayers have been fabricated using La 0.67 Ca 0.33 MnO 3 as the ferromagnetic layer and Pr 0.7 Ca 0.3 MnO 3 and Nd 0.5 Ca 0.5 MnO 3 as the spacer layers. All the multilayers were grown on LaAlO 3 (100) by pulse laser deposition. An enhanced magnetoresistance (defined ( R H - R 0 )/ R 0 ) of more than 98%…
A new mean-field type theory is proposed to study order-disorder transitions (ODT) in block copolymers. The theory applies to both the weak segregation (WS) and the strong segregation (SS) regimes. A new energy functional is proposed without appealing to the random phase approximation (RPA). We find new terms unaccoun…
We have applied first-principles density-functional calculations to the study of the energetics, and the elastic and electronic properties of monatomic wires of Au, Cu, K, and Ca in linear and a planar-zigzag geometries. For Cu and Au wires, the zigzag distortion is favorable even when the linear wire is stretched, bu…
The adsorption of C60 on Si(111) has been studied by means of first-principles density functional calculations. A 2x2 adatom surface reconstruction was used to simulate the terraces of the 7x7 reconstruction. The structure of several possible adsorption configurations was optimized using the ab initio atomic forces, f…
The thermotropic and viscoelastic properties and the structure of thermoreversible organogels composed of enantiomerically pure trans -1,2-bis(3-dodecylureido)cyclohexane ( 1 ) and primary alcohols, i.e., propanol, butanol, hexanol, and octanol, have been investigated by melting-point measurements, differential scanni…
Colloidal biocatalysts, comprising polystyrene (PS) carrier particles coated with enzyme multilayers, were fabricated via the layer-by-layer self-assembly method. Glucose oxidase (GOD), horseradish peroxidase (POD), or preformed enzyme−polyelectrolyte complexes were assembled in alternation with oppositely charged pol…
This paper describes high-temperature reliability, particularly creep and creep rupture behavior of three engineering ceramics—silicon nitride, silicon carbide, and alumina-based silicon-carbide-particulate ceramics—which are considered the most potential candidates for the use of blades of high-efficiency ceramic gas…
We present quasi-steady-state photoinduced absorption measurements on thin films of CdSe nanocrystals dispersed in a polystyrene matrix. For nanocrystals treated with pyridine we observe an intense, size-dependent absorption peaking in the mid-infrared when the samples are irradiated with visible light. This infrared…
This letter reports photoluminescence properties of nanocrystalline BaTiO3. Two intense emission bands centered at 543 and 694 nm and a weak one at 574 nm have been observed at room temperature. The change of luminescence peak with different heat treatments correlates to the evolution of Ti4+ defects in the nanocrysta…
The thermal stress of thin and ultrathin polystyrene (PS) films on Si substrate has been studied and the glass transition temperature (Tg) is determined from the thermal stress data. Tg of PS turned out to be thickness independent for thick films but decreases when the film thickness is comparable to the end-to-end di…
Mass-selected carbon ion beam deposition (MSIBD) was used to demonstrate that the diameter of a carbon nanotube could be as small as 0.4 nm, the theoretical limit predicted but never experimentally reached so far. The deposition was performed at an elevated temperature much lower than the high temperatures (800–1000 °…
The rate for cross slip of screw dislocations during annihilation of screw dipoles in copper is determined by molecular dynamics simulations. The temperature dependence of the rate is seen to obey an Arrhenius behavior in the investigated temperature range: 225-375 K. The activation energy and the effective attempt fr…
Cold-pressed powder compacts of CrO2 show large negative magnetoresistance (MR) due to intergranular tunneling. Powder compacts made from needle-shaped nanoparticles exhibit MR of about 28% at 5 K. Temperature dependence of the resistivity indicates that the Coulomb blockade intergranular tunneling is responsible for…