In-situ STEM imaging of growth and phase change of individual CuAl_X precipitates in Al alloy

Age-hardening in Al alloys has been used for over a century to improve its mechanical properties. However, the lack of direct observation limits our understanding of the dynamic nature of the evolution of nanoprecipitates during age-hardening. Using in-situ (scanning) transmission electron microscopy (S/TEM) while heating an Al-Cu alloy, we...

Temperature dependence of atomic vibrations in mono-layer graphene

We have measured the mean square amplitude of both in- and out-of-plane lattice vibrations for mono-layer graphene at temperatures ranging from ?100 K to 1300?K. The amplitude of lattice vibrations was calculated from data extracted from selected area electron diffraction patterns recorded across a known temperature range with over 80...

Growing LaAlO3/SrTiO3 interfaces by sputter deposition

Sputter deposition of oxide materials in a high-pressure oxygen atmosphere is a well-known technique to produce thin films of perovskite oxides in particular. Also interfaces can be fabricated, which we demonstrated recently by growing LaAlO3 on SrTiO3 substrates and showing that the interface showed the same high degree of epitaxy and atomic...

Unexpected origin of magnetism in monoclinic Nb12O29 from first-principles calculations

Nb12O29 is a 4d transition metal oxide that occurs in two forms with different symmetries, monoclinic (m) and orthorhombic (o). The monoclinic form has unusual magnetic properties; below a temperature of 12 K, it exhibits both metallic conductivity and antiferromagnetic ordering. Here, first-principles density-functional theory calculations are...

Localised corrosion in aluminium alloy 2024-T3 using in situ TEM

An approach to carry out chemical reactions using aggressive gases in situ in a transmission electron microscope (TEM), at ambient pressures of 1.5 bar using a windowed environmental cell, called a nanoreactor, is presented here. The nanoreactor coupled with a specially developed holder with platinum tubing permits the usage of aggressive...

In Situ transmission electron microscopy imaging of electromigration in platinum nanowires

In situ transmission electron microscopy was performed on the electromigration in platinum (Pt) nanowires (14 nm thick, 200 nm wide, and 300 nm long) with and without feedback control. Using the feedback control mode, symmetric electrodes are obtained and the gap usually forms at the center of the Pt nanowire. Without feedback control,...

Non-conducting interfaces of LaAlO3/SrTiO3 produced in sputter deposition: The role of stoichiometry

We have investigated the properties of interfaces between LaAlO3 films grown on SrTiO3 substrates singly terminated by TiO2. We used RF sputtering in a high-pressure oxygen atmosphere. The films are smooth, with flat surfaces. Transmission electron microscopy shows sharp and continuous interfaces with some slight intermixing. The elemental ratio...

Novel ultrafine Fe(C) precipitates strengthen transformation-induced-plasticity steel

A transmission electron microscopy study was conducted on nanoprecipitates formed in Ti microalloyed transformation-inducedplasticity-assisted steels, revealing the presence of Ti(N), Ti2CS and a novel type of ultra-fine Fe(C) precipitate. The matrix/precipitate orientation relationships, sizes and shapes were investigated in detail. The...

Characterization of NbC and (Nb, Ti)N nanoprecipitates in TRIP assisted multiphase steels

Multiphase steels utilising composite strengthening may be further strengthened via grain refinement or precipitation by the addition of microalloying elements. In this study a Nb microalloyed steel comprising martensite, bainite and retained austenite has been studied. By means of transmission electron microscopy (TEM), we have investigated the...

Atomic-scale electron-beam sculpting of defect-free graphene nanostructures

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Crystal fields, disorder, and antiferromagnetic short-range order in Yb0.24Sn0.76Ru

We report extensive measurements on a new compound (Yb0.24Sn0.76)Ru that crystallizes in the cubic CsCl structure. Valence-band photoemission (PES) and L3 x-ray absorption show no divalent component in the 4f configuration of Yb. Inelastic neutron scattering (INS) indicates that the eight-fold degenerate J-multiplet of Yb3+ is split by the...

Superconductivity at 2.3 K in the misfit compound (PbSe)1.16(TiSe2)2

The structural misfit compound (PbSe)1.16(TiSe2)2 is reported. It is a superconductor with a Tc of 2.3 K. (PbSe)1.16(TiSe2)2 derives from a parent compound, TiSe2, which shows a charge-density wave transition and no superconductivity. The crystal structure, characterized by high-resolution electron microscopy and powder x-ray diffraction,...

Superconductivity in CuxBi2Se3 and its Implications for Pairing in the Undoped Topological Insulator

Bi2Se3 is one of a handful of known topological insulators. Here we show that copper intercalation in the van der Waals gaps between the Bi2Se3 layers, yielding an electron concentration of ?2×1020??cm-3, results in superconductivity at 3.8 K in CuxBi2Se3 for 0.12?x?0.15. This demonstrates that Cooper pairing is possible in Bi2Se3 at accessible...

Insulator to correlated metal transition in V1?xMoxO2

Although many materials display the transition from insulating to metallic behavior on doping, only a few, such as VO2, have the right combination of crystal structure and physical properties to serve as model systems. Here we report the electronic and structural characteristics of the insulator to metal transition in V1?xMoxO2, which we have...

Extreme sensitivity of superconductivity to stoichiometry in Fe1+?Se

The recently discovered iron arsenide superconductors appear to display a universal set of characteristic features, including proximity to a magnetically ordered state and robustness of the superconductivity in the presence of disorder. Here we show that superconductivity in Fe1+?Se, which can be considered the parent compound of the...

Superconductivity in noncentrosymmetric Mg10Ir19B16

Mg10Ir19B16, a previously unreported compound in the Mg-Ir-B chemical system, is found to be superconducting at temperatures near 5 K. The fact that the compound exhibits a range of superconducting temperatures between 4 and 5 K suggests that a range of stoichiometries is allowed, though no structural evidence for this is observed. The compound...

Sodium ion ordering in NaxCoO2: Electron diffraction study