Transition from AFM Spin Canting to Spin Glass-AFM Exchange as Particle Size Decreases in LaFeO.

In this work, we have studied structural and magnetic properties of LaFeO as a function of the particle size , from bulk ( >> 1 µm) to nanoscale ( ≈ 30 nm). A large number of twins were observed for large particles that disappear for small particle sizes. This could be related to the softening of the FeO distortion as particle size decreases.

Coexistence of Two Spin Frustration Pathways in the Quantum Spin Liquid CaCrO.

Kagome antiferromagnetic lattices are of high interest because the geometric frustration is expected to give rise to highly degenerated ground states that may host exotic properties such as quantum spin liquid (QSL). CaCrO has been reported to display all the features expected for a QSL. At present, most of the literature reports on samples synthesized with starting materials ratio CaO/CrO 3:1, which leads to a material with small amounts of CaCrO and CaO as secondary phases; this impurity excess affects not only the magnetic properties but also the structural ones.

Local modification of the microstructure and electrical properties of multifunctional Au-YSZ nanocomposite thin films by laser interference patterning.

Nanocomposite films consisting of gold nanoparticles embedded in an yttria-stabilized zirconia matrix (Au-YSZ) have been synthesized with different gold loadings by reactive magnetron sputtering followed by ex situ annealing in air or laser interference patterning (LIP) treatment. It is shown that the electrical conductivity of the nanocomposite films can be modified to a large extent by changing the gold loading, by thermal annealing, or by LIP. The structural and microstructural analyses evidenced the segregation of metallic gold in crystalline form for all synthesis conditions and treatments applied.

Structural elucidation of the Bi(2(n + 2))Mo(n)O(6(n + 1)) (n = 3, 4, 5 and 6) family of fluorite superstructures by transmission electron microscopy.

The cationic framework structure of a whole new family of compounds with the general formula Bi(2(n + 2))Mo(n)O(6(n + 1)) (n = 3, 4, 5 and 6) has been elucidated by transmission electron microscopy (TEM) methods. High-resolution transmission electron microscopy (HRTEM) has been used to postulate heavy-atom models based on the known structure of the n = 3 phase, Bi(10)Mo(3)O(24). These models were tested by HRTEM image simulation, electron diffraction and powder X-ray diffraction simulation methods which agreed with the experimental results.

Ordered rock-salt related nanoclusters in CaMnO2.

Oxygen engineering techniques performed under adequate controlled atmosphere show that the CaMnO(3)-CaMnO(2) topotactic reduction-oxidation process proceeds via oxygen diffusion while the cationic sublattice remains almost unaltered. Extra superlattice reflections in selected area electron diffraction patterns indicate doubling of the CaMnO(2) rock-salt cell along the cubic directions of a distorted rhombohedral cell originated by ordering of Ca(2+) and Mn(2+) ions distributed in nanoclusters into a NaCl-type matrix, as evidenced by dark field electron microscope images. The local nature of the information provided by the transmission electron microscopy techniques used to characterize the rock-salt type Ca(1-x)Mn(x)O(2) solid solution clearly hints at the existence of subtle extra ordering in other upper oxides of the Ca-Mn-O system.

Order, disorder and structural modulations in Bi-Fe-W-O-Br Sillén-Aurivillius intergrowths.

Transmission electron microscopy observations on a new complex oxybromide with nominal composition Bi(4)Fe(1/3)W(2/3)O(8)Br, heated at high temperature, reveal the transformation of its basic structure yielding two types of crystals. The first crystal type shows ordered and disordered extended defects leading to a new family of intergrowths between one Sillén block and n Aurivillius blocks and occasionally between one Aurivillius block and n Sillén blocks. The second type presents a compositionally modulated structure, determined by electron diffraction, with an average composition Bi(4)Fe(1/2)W(1/2)O(8 - delta)Br and unit-cell parameters a = (1/gamma) 3.

Electron microscopy characterization of nanostructured carbon obtained from chlorination of metallocenes and metal carbides.

In this work we report some new well-defined carbon nanostructures produced by direct chlorination of metallocenes (ferrocene and cobaltocene) and NbC, at temperatures from 100 to 900 degrees C. Thus, amorphous carbon nanotubes with variable dimensions depending on reaction temperature were produced from ferrocene. When cobaltocene is the carbon precursor the main product are solid amorphous nanospheres.

The Phase Co(1)(-)(x)()Ni(x)()Sn(2): Structural Variations Based on the Stacking of Two Different Planar Nets.

The investigation of the tin-rich part of the ternary system Co/Ni/Sn yielded the phase Co(1)(-)(x)()Ni(x)()Sn(2) with the range of composition 0.23(3) < x < 0.59(3).