scholarly journals A Partial Anion Disorder in SrVO2H Induced by Biaxial Tensile Strain

Inorganics ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 26 ◽  
Author(s):  
Morito Namba ◽  
Hiroshi Takatsu ◽  
Wataru Yoshimune ◽  
Aurélien Daniel ◽  
Shoichi Itoh ◽  
...  
Keyword(s):  
Tensile Strain ◽  
Secondary Ion Mass Spectrometry ◽  
Intermediate Phase ◽  
Topochemical Reaction ◽  
Epitaxial Strain ◽  
Extended Solids ◽  
Reaction Processes ◽  
Kinetic Trapping ◽  
Secondary Ion ◽  
Biaxial Tensile Strain

SrVO2H, obtained by a topochemical reaction of SrVO3 perovskite using CaH2, is an anion-ordered phase with hydride anions exclusively at the apical site. In this study, we conducted a CaH2 reduction of SrVO3 thin films epitaxially grown on KTaO3 (KTO) substrates. When reacted at 530 °C for 12 h, we observed an intermediate phase characterized by a smaller tetragonality of c/a = 0.96 (vs. c/a = 0.93 for SrVO2H), while a longer reaction of 24 h resulted in the known phase of SrVO2H. This fact suggests that the intermediate phase is a metastable state stabilized by applying tensile strain from the KTO substrate (1.4%). In addition, secondary ion mass spectrometry (SIMS) revealed that the intermediate phase has a hydrogen content close to that of SrVO2H, suggesting a partially disordered anion arrangement. Such kinetic trapping of an intermediate state by biaxial epitaxial strain not only helps to acquire a new state of matter but also advances our understanding of topochemical reaction processes in extended solids.

High Temperature Anatase TiO2 Stabilization in TiO2/Si Multilayer Structures

2012 ◽  
Vol 1443 ◽  
Author(s):  
Helmut Karl ◽  
Martina Schaedler ◽  
Eugen Ruff ◽  
Bernd Stritzker
Keyword(s):  
High Temperature ◽  
Secondary Ion Mass Spectrometry ◽  
Rutile Phase ◽  
Inert Gas ◽  
Multilayer Structures ◽  
Simultaneous Formation ◽  
Transmission Electron ◽  
Reaction Processes ◽  
Secondary Ion ◽  
Si Nanocrystallites

ABSTRACTIn this work TiO2/Si multilayer structures have been grown by sputtering. After rapid thermal annealing in pure inert gas or inert gas with oxygen atmosphere the multilayers have been investigated by high resolution transmission electron microscopy, μ-Raman and dynamic secondary ion mass spectrometry for their structure and anatase/rutile phase composition. It has been found that the photocatalytically more active anatase TiO2 is stabilized and that interdiffusion and chemical reaction processes were strongly hindered up to 1100°C annealing temperature in oxygen containing atmosphere. These findings are of particular importance since only at this high temperature simultaneous formation of embedded Si nanocrystallites can be achieved.

scholarly journals Ferroelectricity and Large Piezoelectric Response of AlN/ScN Superlattice

2018 ◽  
Author(s):  
Mohammad Noor-A-Alam ◽  
Oskar Olszewski ◽  
Michael Nolan
Keyword(s):  
Density Functional ◽  
Tensile Strain ◽  
Piezoelectric Coefficient ◽  
Piezoelectric Properties ◽  
Piezoelectric Response ◽  
Functional Theory ◽  
Epitaxial Strain ◽  
Biaxial Tensile Strain ◽  
Ferroelectric And Piezoelectric Properties ◽  
External Strain

Based on density functional theory, we investigate the ferroelectric and piezoelectric properties of the AlN/ScN superlattice. We find that the polar wurzite (w-ScAlN) structure is mechanically and dynamically stable, and is more stable than the nonpolar hexagonal flat configuration. We show that ferroelectric polarization switching can be possible for epitaxially tensile strained superlattice. Due to the elastic constant C33 softening along with an increase in e33, the piezoelectric coefficient d33 of the superlattice is doubled compared to pure w-AlN. The combined enhancement of Born effective charges (Z33) and the sensitivity of the atomic co-ordinates to external strain (\frac{\partial u_{3}}{\partial\eta_{3}}) is the origin of large piezoelectric constant e33. Moreover, we show that epitaxial biaxial tensile strain significantly enhances the piezo-response, so that d33 is seven times larger than that of w-AlN at 4% strain. The tensile strain results in a huge enhancement in e33by increasing Z33 and \frac{\partial u_{3}}{\partial\eta_{3}}, which boosts the piezoelectric coefficient. As both superlattice growth and epitaxial strain are already experimentally demonstrated in wurzite nitrides, our results show a new, more controlled approach to significantly enhance and tune the piezoelectric response of w-AlN materials.

scholarly journals Ferroelectricity and Large Piezoelectric Response of AlN/ScN Superlattice

2018 ◽  
Author(s):  
Mohammad Noor-A-Alam ◽  
Oskar Olszewski ◽  
Michael Nolan
Keyword(s):  
Density Functional ◽  
Tensile Strain ◽  
Piezoelectric Coefficient ◽  
Piezoelectric Properties ◽  
Piezoelectric Response ◽  
Functional Theory ◽  
Epitaxial Strain ◽  
Biaxial Tensile Strain ◽  
Ferroelectric And Piezoelectric Properties ◽  
External Strain

Based on density functional theory, we investigate the ferroelectric and piezoelectric properties of the AlN/ScN superlattice. We find that the polar wurzite (w-ScAlN) structure is mechanically and dynamically stable, and is more stable than the nonpolar hexagonal flat configuration. We show that ferroelectric polarization switching can be possible for epitaxially tensile strained superlattice. Due to the elastic constant C33 softening along with an increase in e33, the piezoelectric coefficient d33 of the superlattice is doubled compared to pure w-AlN. The combined enhancement of Born effective charges (Z33) and the sensitivity of the atomic co-ordinates to external strain (\frac{\partial u_{3}}{\partial\eta_{3}}) is the origin of large piezoelectric constant e33. Moreover, we show that epitaxial biaxial tensile strain significantly enhances the piezo-response, so that d33 is seven times larger than that of w-AlN at 4% strain. The tensile strain results in a huge enhancement in e33by increasing Z33 and \frac{\partial u_{3}}{\partial\eta_{3}}, which boosts the piezoelectric coefficient. As both superlattice growth and epitaxial strain are already experimentally demonstrated in wurzite nitrides, our results show a new, more controlled approach to significantly enhance and tune the piezoelectric response of w-AlN materials.

Aspects of high-resolution imaging with a scanning ion microprobe

1986 ◽  
Vol 44 ◽  
pp. 750-751
Author(s):  
R. Levi-Setti ◽  
J. M. Chabala ◽  
Y. L. Wang
Keyword(s):  
Metal Ion ◽  
Secondary Ion Mass Spectrometry ◽  
Chromatic Aberration ◽  
Ion Source ◽  
Ion Microprobe ◽  
Emission Pattern ◽  
Intrinsic Resolution ◽  
Resolution Imaging ◽  
20 Nm ◽  
Secondary Ion

We have shown the feasibility of 20 nm lateral resolution in both topographic and elemental imaging using probes of this size from a liquid metal ion source (LMIS) scanning ion microprobe (SIM). This performance, which approaches the intrinsic resolution limits of secondary ion mass spectrometry (SIMS), was attained by limiting the size of the beam defining aperture (5μm) to subtend a semiangle at the source of 0.16 mr. The ensuing probe current, in our chromatic-aberration limited optical system, was 1.6 pA with Ga+ or In+ sources. Although unique applications of such low current probes have been demonstrated,) the stringent alignment requirements which they imposed made their routine use impractical. For instance, the occasional tendency of the LMIS to shift its emission pattern caused severe misalignment problems.

How SIMS microscopy can be used in medicine

1992 ◽  
Vol 50 (2) ◽  
pp. 1602-1603
Author(s):  
Philippe Fragu
Keyword(s):  
Mass Spectrometry ◽  
Biomedical Applications ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Elements ◽  
Biological Applications ◽  
The Past ◽  
Potential Source ◽  
Secondary Ion ◽  
Chemical Integrity ◽  
Scientific Endeavour

The identification, localization and quantification of intracellular chemical elements is an area of scientific endeavour which has not ceased to develop over the past 30 years. Secondary Ion Mass Spectrometry (SIMS) microscopy is widely used for elemental localization problems in geochemistry, metallurgy and electronics. Although the first commercial instruments were available in 1968, biological applications have been gradual as investigators have systematically examined the potential source of artefacts inherent in the method and sought to develop strategies for the analysis of soft biological material with a lateral resolution equivalent to that of the light microscope. In 1992, the prospects offered by this technique are even more encouraging as prototypes of new ion probes appear capable of achieving the ultimate goal, namely the quantitative analysis of micron and submicron regions. The purpose of this review is to underline the requirements for biomedical applications of SIMS microscopy.Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue.

Advances in imaging SIMS studies of stained and BrdU-labelled human metaphase chromosomes

1995 ◽  
Vol 53 ◽  
pp. 932-933
Author(s):  
R. Levi-Setti ◽  
J. M. Chabala ◽  
R. Espinosa ◽  
M. M. Le Beau
Keyword(s):  
High Performance ◽  
Secondary Ion Mass Spectrometry ◽  
Analytical Sensitivity ◽  
Metaphase Chromosomes ◽  
Banding Patterns ◽  
Sector Mass Spectrometer ◽  
Staining Methods ◽  
The University ◽  
Secondary Ion ◽  
Better Than

We have shown previously that isotope-labelled nucleotides in human metaphase chromosomes can be detected and mapped by imaging secondary ion mass spectrometry (SIMS), using the University of Chicago high resolution scanning ion microprobe (UC SIM). These early studies, conducted with BrdU- and 14C-thymidine-labelled chromosomes via detection of the Br and 28CN- (14C14N-> labelcarrying signals, provided some evidence for the condensation of the label into banding patterns along the chromatids (SIMS bands) reminiscent of the well known Q- and G-bands obtained by conventional staining methods for optical microscopy. The potential of this technique has been greatly enhanced by the recent upgrade of the UC SIM, now coupled to a high performance magnetic sector mass spectrometer in lieu of the previous RF quadrupole mass filter. The high transmission of the new spectrometer improves the SIMS analytical sensitivity of the microprobe better than a hundredfold, overcoming most of the previous imaging limitations resulting from low count statistics.

Imaging of Al-Li-Cu alloys with a Scanning Ion Microprobe

1990 ◽  
Vol 48 (2) ◽  
pp. 314-315
Author(s):  
K.K. Soni ◽  
D.B. Williams ◽  
J.M. Chabala ◽  
R. Levi-Setti ◽  
D.E. Newbury
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Equilibrium Phase ◽  
Icosahedral Symmetry ◽  
Ion Microprobe ◽  
X Ray ◽  
Cu Alloys ◽  
Two Phases ◽  
The University ◽  
Secondary Ion

In contrast to the inability of x-ray microanalysis to detect Li, secondary ion mass spectrometry (SIMS) generates a very strong Li+ signal. The latter’s potential was recently exploited by Williams et al. in the study of binary Al-Li alloys. The present study of Al-Li-Cu was done using the high resolution scanning ion microprobe (SIM) at the University of Chicago (UC). The UC SIM employs a 40 keV, ∼70 nm diameter Ga+ probe extracted from a liquid Ga source, which is scanned over areas smaller than 160×160 μm2 using a 512×512 raster. During this experiment, the sample was held at 2 × 10-8 torr.In the Al-Li-Cu system, two phases of major importance are T1 and T2, with nominal compositions of Al2LiCu and Al6Li3Cu respectively. In commercial alloys, T1 develops a plate-like structure with a thickness <∼2 nm and is therefore inaccessible to conventional microanalytical techniques. T2 is the equilibrium phase with apparent icosahedral symmetry and its presence is undesirable in industrial alloys.

Applications of Time-OF-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

1990 ◽  
Vol 48 (2) ◽  
pp. 308-309
Author(s):  
Bruno Schueler ◽  
Robert W. Odom
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Structural Information ◽  
Time Of Flight ◽  
Biological Tissues ◽  
Polymer Surfaces ◽  
Tof Sims ◽  
Secondary Ions ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.

Near-Surface Aggregation of Sn In Heavily Sn-Doped GaAs Films Grown By Molecular Beam Epitaxy

1985 ◽  
Vol 43 ◽  
pp. 368-369
Author(s):  
S. H. Chen
Keyword(s):  
Molecular Beam Epitaxy ◽  
Cross Section ◽  
Electron Spectroscopy ◽  
Molecular Beam ◽  
Surface Segregation ◽  
Secondary Ion Mass Spectrometry ◽  
Specimen Preparation ◽  
Near Surface ◽  
Gaas Films ◽  
Secondary Ion

Sn has been used extensively as an n-type dopant in GaAs grown by molecular-beam epitaxy (MBE). The surface accumulation of Sn during the growth of Sn-doped GaAs has been observed by several investigators. It is still not clear whether the accumulation of Sn is a kinetically hindered process, as proposed first by Wood and Joyce, or surface segregation due to thermodynamic factors. The proposed donor-incorporation mechanisms were based on experimental results from such techniques as secondary ion mass spectrometry, Auger electron spectroscopy, and C-V measurements. In the present study, electron microscopy was used in combination with cross-section specimen preparation. The information on the morphology and microstructure of the surface accumulation can be obtained in a fine scale and may confirm several suggestions from indirect experimental evidence in the previous studies.

Trace nanoanalysis

1994 ◽  
Vol 52 ◽  
pp. 940-941
Author(s):  
D. E. Newbury ◽  
R. D. Leapman
Keyword(s):  
High Performance ◽  
Secondary Ion Mass Spectrometry ◽  
Detection Efficiency ◽  
Volume Element ◽  
And Performance ◽  
Trace Constituents ◽  
Secondary Ion ◽  
Concentration Levels ◽  
Structure Properties

Trace constituents, which can be very loosely defined as those present at concentration levels below 1 percent, often exert influence on structure, properties, and performance far greater than what might be estimated from their proportion alone. Defining the role of trace constituents in the microstructure, or indeed even determining their location, makes great demands on the available array of microanalytical tools. These demands become increasingly more challenging as the dimensions of the volume element to be probed become smaller. For example, a cubic volume element of silicon with an edge dimension of 1 micrometer contains approximately 5×1010 atoms. High performance secondary ion mass spectrometry (SIMS) can be used to measure trace constituents to levels of hundreds of parts per billion from such a volume element (e. g., detection of at least 100 atoms to give 10% reproducibility with an overall detection efficiency of 1%, considering ionization, transmission, and counting).

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