Core-Shell Structural Evolution of Crystalline Silicon Nanoparticles upon Lithiation/Delithiation By Ex Situ Raman Spectroscopy and Operando Synchrotron X-Ray Diffraction

2016 ◽  
Keyword(s):  
Raman Spectroscopy ◽  
Silicon Nanoparticles ◽  
Crystalline Silicon ◽  
Structural Evolution ◽  
Ex Situ ◽  
Core Shell ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Structural Evolution of Layered Manganese Oxysulfides during Reversible Electrochemical Lithium Insertion and Copper Extrusion

2021 ◽  
Author(s):  
Sunita Dey ◽  
Dongli Zeng ◽  
Paul Adamson ◽  
Jordi Cabana ◽  
Sylvio Indris ◽  
...  
Keyword(s):  
Structural Evolution ◽  
Ex Situ ◽  
Discharge Process ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Capacity Retention ◽  
X Ray ◽  
Metallic Particles ◽  
Electrochemical Lithiation ◽  
A Charge

<p>The electrochemical lithiation and delithiation of the layered oxysulfide Sr<sub>2</sub>MnO<sub>2</sub>Cu<sub>4−<i>δ</i></sub>S<sub>3</sub> has been investigated by using a combination of <i>in situ </i>powder X-ray diffraction and <i>ex situ</i> neutron powder diffraction, X ray absorption and Li NMR spectroscopy, together with a range of electrochemical experiments. Sr<sub>2</sub>MnO<sub>2</sub>Cu<sub>4−<i>δ</i></sub>S<sub>3</sub> consists of [Sr<sub>2</sub>MnO<sub>2</sub>] perovskite-type cationic layers alternating with highly defective antifluorite-type [Cu<sub>4−</sub><sub>d</sub>S<sub>3</sub>] (d ~ 0.5) anionic layers. It undergoes a combined displacement/intercalation (CDI) mechanism on reaction with Li, where the inserted Li replaces Cu, forming Li<sub>4</sub>S<sub>3</sub> slabs and Cu<sup>+</sup> is reduced and extruded as metallic particles. For the initial 2-3% of the 1<sup>st</sup> discharge process, the vacant sites in the sulfide layer are filled by Li; Cu extrusion then accompanies further insertion of Li. Mn<sup>2.5+</sup> is reduced to Mn<sup>2+</sup> during the first half of the discharge. The overall charging process involves the removal of Li and re-insertion of Cu into the sulfide layers with re-oxidation of Mn<sup>2+</sup> to Mn<sup>2.5+</sup>. However, due to the different diffusivities of Li and Cu, the processes operating on charge are quite different from those operating during the first discharge: charging to 2.75 V results in removal of most of the Li, little reinsertion of Cu and good capacity retention. A charge to 3.75 V is required to fully reinsert Cu, which results in significant changes to the sulfide sublattice during the following discharge and poor capacity retention. This detailed structure-property investigation will promote the design of new functional electrodes with improved device performance. </p>

Photoluminescence Quantum Yields from Crystalline and Amorphous Silicon Nanoparticles

2007 ◽  
Vol 1056 ◽  
Author(s):  
Rebecca Anthony ◽  
Uwe Kortshagen
Keyword(s):  
Silicon Nanoparticles ◽  
Crystalline Silicon ◽  
Plasma Reactor ◽  
Quantum Yields ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Non Thermal Plasma ◽  
Amorphous Nanoparticles ◽  
Amorphous Silicon Nanoparticles

ABSTRACTThe optical properties of amorphous and crystalline silicon nanoparticles are studied. By tuning the power of the non-thermal plasma reactor, the structure of the particles is adjusted from amorphous to crystalline nanoparticles. The microstructure is studied using transmission electron microscopy, X-ray diffraction, and Raman vibrational spectroscopy. The photoluminescence quantum yields of crystalline nanoparticle samples are consistently higher than those of amorphous nanoparticles.

Raman and dielectric response of BaTi1-x(Mg1/3Nb2/3)xO3 solid solution

2013 ◽  
Vol 03 (04) ◽  
pp. 1350030 ◽  
Author(s):  
Jingji Zhang ◽  
Ludong Ji ◽  
Jiangying Wang
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Raman Spectroscopy ◽  
Dielectric Response ◽  
Critical Concentration ◽  
Structural Evolution ◽  
Dielectric Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermally Activated

Structural evolution and dielectric analysis have been performed for BaTi 1-x( Mg 1/3 Nb 2/3)x O 3 solid solutions with x ≤ 0.07, together with the analysis of Raman spectroscopy. X-Ray diffraction and Raman results show a structural evolution from a tetragonal phase to a cubic one with increasing x. Dielectric analysis reveals a low critical concentration corresponding to ferroelectric–relaxor crossover (xc = 0.05). Activation energy with dozens meV is obtained using the Vogel–Fulcher relationship, which is attributed to thermally activated off-center ion hopping.

scholarly journals Structural Evolution of Layered Manganese Oxysulfides during Reversible Electrochemical Lithium Insertion and Copper Extrusion

2021 ◽  
Author(s):  
Sunita Dey ◽  
Dongli Zeng ◽  
Paul Adamson ◽  
Jordi Cabana ◽  
Sylvio Indris ◽  
...  
Keyword(s):  
Structural Evolution ◽  
Ex Situ ◽  
Discharge Process ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Capacity Retention ◽  
X Ray ◽  
Metallic Particles ◽  
Electrochemical Lithiation ◽  
A Charge

<p>The electrochemical lithiation and delithiation of the layered oxysulfide Sr<sub>2</sub>MnO<sub>2</sub>Cu<sub>4−<i>δ</i></sub>S<sub>3</sub> has been investigated by using a combination of <i>in situ </i>powder X-ray diffraction and <i>ex situ</i> neutron powder diffraction, X ray absorption and Li NMR spectroscopy, together with a range of electrochemical experiments. Sr<sub>2</sub>MnO<sub>2</sub>Cu<sub>4−<i>δ</i></sub>S<sub>3</sub> consists of [Sr<sub>2</sub>MnO<sub>2</sub>] perovskite-type cationic layers alternating with highly defective antifluorite-type [Cu<sub>4−</sub><sub>d</sub>S<sub>3</sub>] (d ~ 0.5) anionic layers. It undergoes a combined displacement/intercalation (CDI) mechanism on reaction with Li, where the inserted Li replaces Cu, forming Li<sub>4</sub>S<sub>3</sub> slabs and Cu<sup>+</sup> is reduced and extruded as metallic particles. For the initial 2-3% of the 1<sup>st</sup> discharge process, the vacant sites in the sulfide layer are filled by Li; Cu extrusion then accompanies further insertion of Li. Mn<sup>2.5+</sup> is reduced to Mn<sup>2+</sup> during the first half of the discharge. The overall charging process involves the removal of Li and re-insertion of Cu into the sulfide layers with re-oxidation of Mn<sup>2+</sup> to Mn<sup>2.5+</sup>. However, due to the different diffusivities of Li and Cu, the processes operating on charge are quite different from those operating during the first discharge: charging to 2.75 V results in removal of most of the Li, little reinsertion of Cu and good capacity retention. A charge to 3.75 V is required to fully reinsert Cu, which results in significant changes to the sulfide sublattice during the following discharge and poor capacity retention. This detailed structure-property investigation will promote the design of new functional electrodes with improved device performance. </p>

Interfacial properties of GaSb/InAs superlattices

1993 ◽  
Vol 51 ◽  
pp. 826-827
Author(s):  
M. E. Twigg ◽  
B. R. Bennett ◽  
J. R. Waterman ◽  
J. L. Davis ◽  
B. V. Shanabrook ◽  
...  
Keyword(s):  
Gaas Substrate ◽  
Molecular Beam ◽  
Infrared Detector ◽  
Interfacial Properties ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
Absorption Coefficients ◽  
X Ray ◽  
Short Period ◽  
High Optical Absorption

Recently, the GaSb/InAs superlattice system has received renewed attention. The interest stems from a model demonstrating that short period Ga1-xInxSb/InAs superlattices will have both a band gap less than 100 meV and high optical absorption coefficients, principal requirements for infrared detector applications. Because this superlattice system contains two species of cations and anions, it is possible to prepare either InSb-like or GaAs-like interfaces. As such, the system presents a unique opportunity to examine interfacial properties.We used molecular beam epitaxy (MBE) to prepare an extensive set of GaSb/InAs superlattices grown on an GaSb buffer, which, in turn had been grown on a (100) GaAs substrate. Through appropriate shutter sequences, the interfaces were directed to assume either an InSb-like or GaAs-like character. These superlattices were then studied with a variety of ex-situ probes such as x-ray diffraction and Raman spectroscopy. These probes confirmed that, indeed, predominantly InSb-like and GaAs-like interfaces had been achieved.

Raman spectroscopy and X-ray diffraction of lithium niobate at temperatures up to 1300○-4.80pt○C

2005 ◽  
Vol 126 ◽  
pp. 101-105 ◽  
Author(s):  
B. Moulin ◽  
L. Hennet ◽  
D. Thiaudière ◽  
P. Melin ◽  
P. Simon
Keyword(s):  
Raman Spectroscopy ◽  
Lithium Niobate ◽  
X Ray Diffraction ◽  
X Ray

STRUCTURAL EVOLUTION OF EXCEPTIONALLY IRON-DEFICIENT HEMATITE NANOCRYSTALS AS OBSERVED BY IN SITU SYNCHROTRON X-RAY DIFFRACTION

2019 ◽  
Author(s):  
Si Athena Chen ◽  
◽  
Peter Heaney ◽  
Jeffrey E. Post ◽  
Peter J. Eng ◽  
...  
Keyword(s):  
Structural Evolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Iron Deficient

In Situ X-Ray Diffraction Investigations during Diffusion Anneals of Ni-Cu Thin Film Diffusion Couples

2010 ◽  
Vol 89-91 ◽  
pp. 503-508 ◽  
Author(s):  
J. Sheng ◽  
U. Welzel ◽  
Eric J. Mittemeijer
Keyword(s):  
Thermal Stresses ◽  
Stress Generation ◽  
Ex Situ ◽  
Diffusion Annealing ◽  
X Ray Diffraction ◽  
Individual Layer ◽  
X Ray ◽  
Bilayer System ◽  
Stress Changes

The stress evolution during diffusion annealing of Ni-Cu bilayers (individual layer thicknesses of 50 nm) was investigated employing ex-situ and in-situ X-ray diffraction measurements. Annealing at relatively low homologous temperatures (about 0.3 - 0.4 Tm) for durations up to about 100 hours results in considerable diffusional intermixing, as demonstrated by Auger-electron spectroscopy investigations (in combination with sputter-depth profiling). In addition to thermal stresses due to differences of the coefficients of thermal expansion of layers and substrate, tensile stress con-tributions in the sublayers arise during the diffusion anneals. The obtained stress data have been discussed in terms of possible mechanisms of stress generation. The influence of diffusion on stress development in the sublayers of the diffusion couple during heating and isothermal annealing was investigated by comparing stress changes in the bilayer system with corresponding results obtained under identical conditions for single layers of the components in the bilayer system. The specific residual stresses that emerge due to diffusion between the (sub)layers in the bilayer could thereby be identified.

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