Magnetoresistance at Room Temperature of Oleic Acid Coated Fe3-xCoxO4 (x = 0, 0.1 and 0.3) Nanocrystal Drop-Cast Films

Oleic acid coated Fe3-xCoxO4 (x = 0, 0.1 and 0.3) nanocrystal self-assembled films were fabricated via drop-casting of colloidal particles on a SiO2/Si substrate. Nanocrystals of the Fe3-xCoxO4 exhibited bifurcation of the zero-field-cooled and field-cooled magnetizations at 300 K. The Fe3-xCoxO4 nanocrystal drop-cast films demonstrated nonlinear current-voltage characteristics between the source and drain electrodes in magnetic fields of zero and 0.2 T, and magnetoresistance reached into −46% for the x = 0 film and −50% for both the x = 0.1 and 0.3 films at 300 K. Oleic acid coated Fe3-xCoxO4 (x = 0.1 and 0.3) nanocrystal would boost developments of a high performance current switching device using negative magnetoresistance

Response to "Comment on `Quantum-confinement effects on the optical and dielectric properties for mesocrystals of BaTiO3 and SrBi2Ta2O9\u27"

In this reply, the authors show that the argument by Scott regarding the band gap of bulk SrBi2Ta2O9 (SBT) is not based on concrete evidence. The authors will also show additional data from a Raman study of a powdered SBT sample to prove that the surface of the specimen was not covered by Bi2O3

Composition and structure of Pd nanoclusters in SiOx_x thin film

The nucleation, distribution, composition and structure of Pd nanocrystals in SiO$_2$ multilayers containing Ge, Si, and Pd are studied using High Resolution Transmission Electron Microscopy (HRTEM) and X-ray Photoelectron Spectroscopy (XPS), before and after heat treatment. The Pd nanocrystals in the as deposited sample seem to be capped by a layer of PdO$_x$. A 1-2 eV shift in binding energy was found for the Pd-3d XPS peak, due to initial state Pd to O charge transfer in this layer. The heat treatment results in a decomposition of PdO and Pd into pure Pd nanocrystals and SiO$_2$

Large frequency dependence of lowered maximum dielectric constant temperature of LiTaO3 nanocrystals dispersed in mesoporous silicate

A large frequency dependence of the maximum dielectric constant temperature was observed for LiTaO3 nanocrystals (the diameter 20 Å) dispersed in mesoporous silicate. At the applied field frequency of 100 kHz, the maximum temperatures in the real and imaginary parts were 365 and 345 °C, respectively. The maximum temperature in the real part is apparently lower than the paraelectric–ferroelectric transition temperature (645 °C) of bulk LiTaO3. The maximum temperature in the imaginary part rose from 285 to 420 °C with increasing frequency from 10 to 1000 kHz. Since the bulk LiTaO3 shows no relaxor behavior, such superparaelectric behavior is obviously a consequence of nanominiaturization of LiTaO3 crystal and insignificant cooperative interactions between the nanoparticles

The Ge(001) (2 × 1) reconstruction: asymmetric dimers and multilayer relaxation observed by grazing incidence X-ray diffraction

Grazing incidence X-ray diffraction has been used to analyze in detail the atomic structure of the (2 × 1) reconstruction of the Ge(001) surface involving far reaching subsurface relaxations. Two kinds of disorder models, a statistical and a dynamical were taken into account for the data analysis, both indicating substantial disorder along the surface normal. This can only be correlated to asymmetric dimers. Considering a statistical disorder model assuming randomly oriented dimers the analysis of 13 symmetrically independent in-plane fractional order reflections and of four fractional order reciprocal lattice rods up to the maximum attainable momentum transfer qz = 3c* (c* = 1.77 × 10−1 Å−1) indicates the formation of asymmetric dimers characterized by R>D = 2.46(5) Å as compared to the bulk bonding length of R = 2.45 Å. The dimer height of Δ Z = 0.74(15) Å corresponds to a dimer buckling angle of 17(4)°. The data refinement using anisotropic thermal parameters leads to a bonding length of RD = 2.44(4) Å and to a large anisotropy of the root mean-square vibration amplitudes of the dimer atoms (u112) 1/2 = 0.25 Å, (u222)1/2 = 0.14 Å, (u332)1/2 = 0.50 Å). We have evidence for lateral and vertical disp tenth layer below the surface

Synthesis and Magnetic Properties of Fergusonite Structured La(NbVMn)O4

The authors have synthesized fergusonite-structured La(Nb0·71V0·04Mn0·25)O4 samples. The samples, consisting of La3+, Nb5+, V5+, Mn4+ and oxygen ions, demonstrated temperature-dependent magnetization that increased with lowering the temperature below ≈200 K, and almost saturated below ≈100 K. At 75 K, the field-dependent magnetization demonstrated sigmoidal curve and reached 3 μB/Mn at 1 T. Such a magnetic behavior can be ascribed to exchange interaction between Mn4+Nb2O11 nanoclusters. The Mn4+ substitution for the V5+ sites of the crystal resulted also in the occupied state above the valence band maximum