Phase Transformations in physical mixtures of Pd-Cu nanoparticles

2013 ◽  
Vol 1528 ◽  
Author(s):  
Vineetha Mukundan ◽  
Jun Yin ◽  
Chuan-Jian Zhong ◽  
Oana Malis
Keyword(s):  
Structural Phase ◽  
Alloy Nanoparticles ◽  
Thermal Treatments ◽  
Cu Nanoparticles ◽  
X Ray Diffraction ◽  
Structural Phase Transformation ◽  
X Ray ◽  
Random Alloy ◽  
Physical Mixtures

ABSTRACTThe temperature induced structural transformations in physical mixtures of 1nm palladium and ultrafine (∼0.5nm) copper nanoparticles supported on carbon were studied using in-situ real time synchrotron based x-ray diffraction. These nanoparticles were subjected to two-step thermal annealing from 25°C to 700°C. The Pd and Cu nanoparticles were found to coalesce forming alloy nanoparticles that subsequently undergo a structural phase transformation from ordered B2 to disordered fcc. The random alloy formed at the end of the thermal treatments was found to be copper-rich.

scholarly journals Gas-induced selective re-orientation of Au–Cu nanoparticles on TiO2 (110)

Nanoscale ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 752-761 ◽  
Author(s):  
Axel Wilson ◽  
Aude Bailly ◽  
Romain Bernard ◽  
Yves Borensztein ◽  
Alessandro Coati ◽  
...  
Keyword(s):  
Bimetallic Nanoparticles ◽  
Grazing Incidence ◽  
Low Pressure ◽  
Photoemission Spectroscopy ◽  
Cu Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures

Au–Cu bimetallic nanoparticles (NPs) grown on TiO2(110) have been followed in situ using grazing incidence X-ray diffraction and X-ray photoemission spectroscopy from their synthesis to their exposure to a CO/O2 mixture at low pressure (P < 10−5 mbar) and at different temperatures (300 K–470 K).

Electrical Transport and In-Situ X-Ray Studies of the Formation of TiSi2 Thin Films on Si

1986 ◽  
Vol 77 ◽  
Author(s):  
J. C. Hensel ◽  
J. M. Vandenberg ◽  
L. F. Mattheiss ◽  
F. C. Unterwald ◽  
A. Maury
Keyword(s):  
Thin Films ◽  
Electrical Transport ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
Metallic Behavior ◽  
Distinctive Features ◽  
X Ray ◽  
Total Energies ◽  
Sputter Deposited

ABSTRACTThe formation of TiSi2 thin films on Si has been investigated by in situ x-ray diffraction and by electrical transport. The x-ray results show unequivocally that the staging proceeds through two orthorhombic polytypes of TiSi2 according to the sequence: sputter-deposited metallic Ti films on Si (001) → TiSi2 (C49 structure) → TiSi2 (C54 structure), with no evidence of lower suicides. Electrical transport shows metallic behavior for all phases and distinctive features in the annealing curves which correlate with the structural transformations. Most importantly, the resistivity, characteristically very high for the C49 phase, undergoes a precipitous drop at the C49 → C54 transition. Total energies for both phases are calculated and, consistent with the occurrence of a structural phase transformation, are found not to differ appreciably.

Powder X-ray diffraction and Rietveld analysis of La1−xBaxCoO3 (0

2006 ◽  
Vol 21 (4) ◽  
pp. 304-306 ◽  
Author(s):  
Wanju Luo ◽  
Fangwei Wang
Keyword(s):  
Phase Transformation ◽  
Bond Length ◽  
Structural Properties ◽  
Powder Diffraction ◽  
Bond Angle ◽  
Structural Phase ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Structural Phase Transformation ◽  
X Ray

Detailed structural properties of La1−xBaxCoO3 (LBCO) have been investigated by means of X-ray powder diffraction and Rietveld analysis. A structural phase transformation from R3c to Pm3m at x=0.30–0.35 has been detected based on a comparison between the refinements of R3c and Pm3m. The Co–O bond length of the CoO6 octahedron expanded rapidly with increasing Ba content when x<0.1, and then it leveled off and kept constant at 0.1⩽x⩾0.35, where the Co–O–Co bond angle reaches 180°. The Co–O bond length expansion resumed with increasing Ba content beyond x=0.35.

Experimental Considerations and Limitations in the Application of Ultra High Temperature (2100°C) X-Ray Diffraction

1991 ◽  
Vol 35 (A) ◽  
pp. 425-429
Author(s):  
Sampath S. Iyengar
Keyword(s):  
High Temperature ◽  
Crystalline Material ◽  
Thermal Treatments ◽  
Ceramic Fibers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Controlled Atmospheres ◽  
Heat Treated ◽  
Multiple Samples

In-situ, high temperature X-ray diffraction (XRD) is an extremely useful tool for studying, monitoring or investigating crystal structure modifications as well as phase transformations in crystalline material during thermal treatments in controlled atmospheres. This technique has been used to investigate the thermal behavior of materials such as carbonate minerals, ceramic fibers, coating pigments, etc. The advantages of such a technique over the conventional practice, where samples are heat treated in a separate oven and then analyzed by XRD include: consistency of sample placement; preservation of high temperature structures to facilitate observation of metastable phases that are unstable upon exposure to outside atmosphere or during cooling; real time monitoring of reactions that occur, and products that are formed at a desired temperature or environment; and need for multiple samples or analysis.

scholarly journals A highly efficient and multifunctional biomass supporting Ag, Ni, and Cu nanoparticles through wetness impregnation for environmental remediation

2019 ◽  
Vol 8 (1) ◽  
pp. 309-319 ◽  
Author(s):  
Shahid Ali Khan ◽  
Muhammad Ismail ◽  
Yasir Anwar ◽  
Aliya Farooq ◽  
Bassam Oudh Al Johny ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Attenuated Total Reflectance ◽  
Gravimetric Analysis ◽  
Cu Nanoparticles ◽  
X Ray Diffraction ◽  
Total Reflectance ◽  
X Ray ◽  
Wide Range ◽  
Bactericidal Activities

Abstract Plant-based materials are reported to have a wide range of applications in the environmental and biomedical sectors. In this report, we present an economic and environmentally friendly supported turmeric powder (TP) biomass for the support of Ag, Ni and Cu nanoparticles (NPs) designated as Ag@TP, Ni@TP and Cu@TP. The in situ syntheses of the stated NPs were achieved in aqueous medium using NaBH4 as a reducing agent. The prepared NPs were applied for the degradation of o-nitrophenol (ONP), m-nitrophenol (MNP), p-nitrophenol (PNP), methyl orange (MO), Congo red (CR), rhodamine B (RB) and methylene blue (MB). Initially, Ag@TP, Ni@TP and Cu@TP were screened for the MO dye and antibacterial activity, where Ag@TP displayed the strongest catalytic activity for MO and bactericidal activities as compared to Ni@TP and Cu@TP. The quantity of metal ions adsorbed onto the TP was investigated by atomic absorption spectroscopy. The Ag@TP, Ni@TP and Cu@TP were characterized through X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, thermal gravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscope (FESEM) analysis.

Powder X-ray diffraction and Rietveld analysis of La1−xCaxMnO3(0

2006 ◽  
Vol 21 (1) ◽  
pp. 40-44 ◽  
Author(s):  
P. R. Sagdeo ◽  
Shahid Anwar ◽  
N. P. Lalla
Keyword(s):  
Phase Transformation ◽  
Calcium Concentration ◽  
Single Phase ◽  
Structural Phase ◽  
Rietveld Analysis ◽  
Linear Variation ◽  
X Ray Diffraction ◽  
Structural Phase Transformation ◽  
Magnetic Phases ◽  
X Ray

Single-phase samples of La1−xCaxMnO3compounds have been synthesized by solid-state reaction. Detailed Rietveld analysis of powder X-ray diffraction data showed that La1−xCaxMnO3undergoes a structural phase transformation fromR-3ctoPnmaatX=0.05–0.075. There is a linear variation of lattice parameters as a function of calcium concentration. The slope of this linear variation changes atX=0.6. A correlation between observed Mn-O bond lengths, corresponding to different compositions, and possible magnetic phases is discussed.

scholarly journals High-Pressure Behaviors of Ag2S Nanosheets: An in Situ High-Pressure X-Ray Diffraction Research

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1640
Author(s):  
Ran Liu ◽  
Bo Liu ◽  
Quan-Jun Li ◽  
Bing-Bing Liu
Keyword(s):  
High Pressure ◽  
Phase I ◽  
Phase Ii ◽  
Structural Phase ◽  
Phase Iii ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Phase ◽  
Ag2s Nanoparticles

An in situ high-pressure X-ray diffraction study was performed on Ag2S nanosheets, with an average lateral size of 29 nm and a relatively thin thickness. Based on the experimental data, we demonstrated that under high pressure, the samples experienced two different high-pressure structural phase transitions up to 29.4 GPa: from monoclinic P21/n structure (phase I, α-Ag2S) to orthorhombic P212121 structure (phase II) at 8.9 GPa and then to monoclinic P21/n structure (phase III) at 12.4 GPa. The critical phase transition pressures for phase II and phase III are approximately 2–3 GPa higher than that of 30 nm Ag2S nanoparticles and bulk materials. Additionally, phase III was stable up to the highest pressure of 29.4 GPa. Bulk moduli of Ag2S nanosheets were obtained as 73(6) GPa for phase I and 141(4) GPa for phase III, which indicate that the samples are more difficult to compress than their bulk counterparts and some other reported Ag2S nanoparticles. Further analysis suggested that the nanosize effect arising from the smaller thickness of Ag2S nanosheets restricts the relative position slip of the interlayer atoms during the compression, which leads to the enhancing of phase stabilities and the elevating of bulk moduli.

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