108,325 research outputs found
Indium substitution effect on the topological crystalline insulator family (PbSn)InTe: Topological and superconducting properties
Topological crystalline insulators (TCIs) have been of great interest in the
area of condensed matter physics. We investigated the effect of indium
substitution on the crystal structure and transport properties in the TCI
system (PbSn)InTe. For samples with a tin
concentration , the low-temperature resisitivities show a dramatic
variation as a function of indium concentration: with up to ~2% indium doping
the samples show weak-metallic behavior, similar to their parent compounds;
with ~6% indium doping, samples have true bulk-insulating resistivity and
present evidence for nontrivial topological surface states; with higher indium
doping levels, superconductivity was observed, with a transition temperature,
Tc, positively correlated to the indium concentration and reaching as high as
4.7 K. We address this issue from the view of bulk electronic structure
modified by the indium-induced impurity level that pins the Fermi level. The
current work summarizes the indium substitution effect on (Pb,Sn)Te, and
discusses the topological and superconducting aspects, which can be provide
guidance for future studies on this and related systems.Comment: 16 pages, 8 figure
Method for attaching a fused-quartz mirror to a conductive metal substrate
A fused-quartz mirror is attached to a conductive metal substrate by the following steps: tinning one surface of a fused-quartz mirror with a solder of substantially pure indium; tinning a metallic substrate with an indium eutectic alloy consisting essentially of indium bismuth, lead and tin having a melting point substantially below that of indium; heating the eutectic alloy to a temperature substantially above its melting point, but below that of the solder; floating the mirror into place, and subsequently cooling the alloy to a temperature substantially below its melting point
Competitive segregation of gallium and indium at heterophase Cu–MnO interfaces studied with transmission electron microscopy
This paper concentrates on the possible segregation of indium and gallium and competitive segregation of gallium and indium at atomically flat parallel {111}-oriented Cu–MnO interfaces. The segregation of gallium at Cu–MnO interfaces after introduction of gallium in the copper matrix of internally oxidized Cu–1 at.%Mn could be hardly detected with energy-dispersive spectrometry in a field emission gun transmission electron microscope. After a heat treatment to dissolve indium in the copper matrix, gallium has a weak tendency to segregate, that is 2.5 at.% Ga per monolayer at the interface compared with 2 at.% in the copper matrix. The striking result is that this gallium segregation is observable because it does not occur at the metal side of the interface but in the first two monolayers at the oxide side. Using the same heat treatment as for introducing indium in the sample, but without indium present, gallium segregates strongly at the oxide side of the Cu–MnO interface with a concentration of about 14.3 at.% in each monolayer of the two. In contrast, the presence of gallium has no influence on the segregation of indium towards Cu–MnO interfaces, because the outermost monolayer at the metal side of the interface contains 17.6 at.% In, that is similar to previously found results. This leads to the intriguing conclusions, firstly, that, in contrast with antimony and indium, gallium segregates at the oxide side of the interface and, secondly, that the presence of indium strongly hampers gallium segregation. The results from analytical transmission electron microscopy on gallium segregation are supported by high-resolution transmission electron microscopy observations.
Direct Observation of Early-stage Quantum Dot Growth Mechanisms with High-temperature Ab Initio Molecular Dynamics
Colloidal quantum dots (QDs) exhibit highly desirable size- and
shape-dependent properties for applications from electronic devices to imaging.
Indium phosphide QDs have emerged as a primary candidate to replace the more
toxic CdSe QDs, but production of InP QDs with the desired properties lags
behind other QD materials due to a poor understanding of how to tune the growth
process. Using high-temperature ab initio molecular dynamics (AIMD)
simulations, we report the first direct observation of the early stage
intermediates and subsequent formation of an InP cluster from separated indium
and phosphorus precursors. In our simulations, indium agglomeration precedes
formation of In-P bonds. We observe a predominantly intercomplex pathway in
which In-P bonds form between one set of precursor copies while the carboxylate
ligand of a second indium precursor in the agglomerated indium abstracts a
ligand from the phosphorus precursor. This process produces an indium-rich
cluster with structural properties comparable to those in bulk zinc-blende InP
crystals. Minimum energy pathway characterization of the AIMD-sampled reaction
events confirms these observations and identifies that In-carboxylate
dissociation energetics solely determine the barrier along the In-P bond
formation pathway, which is lower for intercomplex (13 kcal/mol) than
intracomplex (21 kcal/mol) mechanisms. The phosphorus precursor chemistry, on
the other hand, controls the thermodynamics of the reaction. Our observations
of the differing roles of precursors in controlling QD formation strongly
suggests that the challenges thus far encountered in InP QD synthesis
optimization may be attributed to an overlooked need for a cooperative tuning
strategy that simultaneously addresses the chemistry of both indium and
phosphorus precursors.Comment: 40 pages, 9 figures, submitted for publicatio
Indium adhesion provides quantitative measure of surface cleanliness
Indium tipped probe measures hydrophobic and hydrophilic contaminants on rough and smooth surfaces. The force needed to pull the indium tip, which adheres to a clean surface, away from the surface provides a quantitative measure of cleanliness
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