Materials Literature
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Ta 2 O 5 films deposited on Si substrates were investigated using transmission Fourier-transform infrared spectroscopy. We found a new absorption peak at 2340 cm−1 that can be characterized as a stretching vibration mode due to Ta=O bonds in the films. This peak appeared following annealing in O2 ambient, but not in N…
Recent studies have shown the application of amorphous carbon as a semiconductor in C/Si heterojunction photovoltaic solar cells. In this letter, we report the rectifying current–voltage characteristics of the phosphorus-doped carbon/undoped-carbon (n-C/p-C) junction. The p- and n-carbon films were deposited by pyroly…
In situ transmission electron microscopy study of electric field-induced cracking has been conducted on 〈001〉 oriented 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 crystal. Fracture of the 90° domain boundary was directly observed in the tetragonal area under both static and alternating electric fields. The field strength required…
We have measured high spatial/depth resolution (∼2–3 μm) thermal conductivity (κ) at 300 K of both fully and partially coalesced GaN/sapphire (0001) samples fabricated by lateral epitaxial overgrowth. On the fully coalesced sample we found 1.86W/cm K<κ<2.05 W/cm K over a distance of approximately 50 μm.…
A phenomenological model was proposed which describes frequency dispersion of nonlinear dielectric response of relaxor ferroelectrics (relaxors) as a result of dispersion of their linear dielectric permittivity. The model was applied to Pb(Mg(1/3)Nb(2/3))O3 (PMN) relaxor. It provided a good qualitative description of…
The dielectric properties, ferroelectric polarization, and piezoelectric strain behavior of Ba(Ti1−xZrx)O3 (x=0.05 and 0.08) single crystals are studied for different crystal orientations. The study of dielectric properties suggests that the three phase transitions in BaTiO3 are pinched by substituting Ti with Zr but…
A class of promising permanent-magnet materials with an appreciable high-temperature coercivity of 8.6 kOe at 500 °C is reported. The Sm–Co–Cu–Ti magnets are prepared by arc melting and require a suitable heat treatment. Magnetization measurements as a function of temperature and x-ray diffraction patterns indicate th…
Magnetostriction measurements have been made in an ordered Fe3Pt single crystal with degree of order of about 0.8, which exhibits a cubic-tetragonal martensitic transformation at 97 K. The specimen was cooled down to 4.2 K without magnetic field, and then a magnetic field of 4 T is applied to the specimen along 〈001〉…
Low temperature resistivity of CMR manganites is investigated. At the ground state, conduction electrons are perfectly spin polarized, which is called half-metallic. From one-magnon scattering processes, it is discussed that the resistivity of a half metal as a function of temperature scales as rho(T) - rho(0) propto…
An experimental proof-of-principle of an enhanced Z3DT (thermoelectric figure of merit) is demonstrated using (001) oriented Si/Ge superlattices. The highest value of the experimental Z3DT at 300 K for a (001) oriented Si(20 Å)/Ge(20 Å) superlattice is 0.1 using κ=5 Wm−1 K−1, for the in-plane thermal conductivity, whi…
The internal thermalization dynamics of the conduction electrons is investigated in silver nanoparticles with radius ranging from 13 to 1.6 nm using a femtosecond IR pump-UV probe absorption saturation technique. A sharp increase of the electron energy exchange rate is demonstrated for nanoparticles smaller than 5 nm.…
In an attempt to reproduce the functional properties associated with relaxor electroceramics, pulsed laser deposition has been used to fabricate thin-film capacitor structures in which the dielectric layer is composed of a superlattice of Ba0.8Sr0.2TiO3 and Ba0.2Sr0.8TiO3. The properties of the capacitors were investi…
The adsorption behavior of positively charged poly(propylene imine) dendrimers on glass has been studied by scanning angle reflectometry as a function of generation, pH, and ionic strength. The results indicate that the adsorption is controlled by properties of both the dendrimers (size and charge) and the surface lay…
Lamellar organoammonium silicates with variable silicon environments have been synthesized by the reaction of a layered polysilicate kanemite with aqueous solutions of hexadecyltrimethylammonium (C 16 TMA) chloride. While the structure of kanemite is composed of only Q 3 silicate species ((SiO) 3 Si O), SiO 4 units wi…
We have prepared a linear array of chromophores consisting of a perylene input unit, a bis(free base porphyrin) transmission unit, and a free base phthalocyanine output unit for studies in artificial photosynthesis and molecular photonics. The synthesis involved four stages: (1) a rational synthesis of trans-AB2C-porp…
Effective pair potentials for hollow nanoparticles like the ones made from carbon (fullerenes) or metal dichalcogenides (inorganic fullerenes) consist of a hard core repulsion and a deep, but short-ranged, van der Waals attraction. We investigate them for single- and multi-walled nanoparticles and show that in both ca…
We study thermal relaxation in ordered arrays of coupled nonlinear elements with external driving. We find, that our model exhibits dynamic self-organization manifested in a universal stretched-exponential form of relaxation. We identify two types of self-organization, cooperative and anti-cooperative, which lead to f…
A study has been made of the electrical resistivity ρ, magnetoresistance Δρ/ρ, and magnetization of La 0.35 Nd 0.35 Sr 0.3 MnO 3 epitaxial films on ZrO 2 (Y 2 O 3 ), SrTiO 3 , LaAlO 3 , and MgO substrates. The first film can exist in four equivalent crystallographic orientations in the sample plane, while the other th…
New crystals of the composition Er 2 (SO 4 ) 3 ⋅ 8H 2 O have been synthesized by the method similar to that used for synthesis of (CH 3 ) 2 NH 2 Al(SO 4 ) 2 ⋅ 6H 2 O. The synthesized crystals were studied by the X-ray diffraction method. The crystals are monoclinic C 2/ c ) and contain no (CH 3 ) 2 NH 2 ions. It is es…
A new detection system in scanning electron microscope, which filters in energy and detects the backscattered electrons close to the microscope axis, is described. This technique ameliorates the dependence of the backscattering coefficient on atomic number, and suppresses effectively the relief contrast at the same ti…