scholarly journals ASSOCIATIVE CULTURES OF CHEMOLITHOTROPHIC MICROORGANISMS AND THEIR ROLE IN LEACHING OF NOBLE METALS FROM KAZAKHSTAN ORES

2016 ◽  
Author(s):  
Ashimkhan Kanayev
Keyword(s):  
Noble Metals

Growth of near noble metal Pd and Pt thin film silicides morphology and structure

1984 ◽  
Vol 42 ◽  
pp. 498-499
Author(s):  
E. I. Alessandrini ◽  
M. O. Aboelfotoh
Keyword(s):  
Noble Metals ◽  
Annealing Temperature ◽  
Chemical Compounds ◽  
Barrier Properties ◽  
Solid State Reactions ◽  
Transmission Electron ◽  
Stable Chemical ◽  
Metal Thickness ◽  
Amorphous Si ◽  
Si Films

Considerable interest has been generated in solid state reactions between thin films of near noble metals and silicon. These metals deposited on Si form numerous stable chemical compounds at low temperatures and have found applications as Schottky barrier contacts to silicon in VLSI devices. Since the very first phase that nucleates in contact with Si determines the barrier properties, the purpose of our study was to investigate the silicide formation of the near noble metals, Pd and Pt, at very thin thickness of the metal films on amorphous silicon.Films of Pd and Pt in the thickness range of 0.5nm to 20nm were made by room temperature evaporation on 40nm thick amorphous Si films, which were first deposited on 30nm thick amorphous Si3N4 membranes in a window configuration. The deposition rate was 0.1 to 0.5nm/sec and the pressure during deposition was 3 x 10 -7 Torr. The samples were annealed at temperatures in the range from 200° to 650°C in a furnace with helium purified by hot (950°C) Ti particles. Transmission electron microscopy and diffraction techniques were used to evaluate changes in structure and morphology of the phases formed as a function of metal thickness and annealing temperature.

Microstructure and reactivity of small metal particles: The role of Ce additives

1992 ◽  
Vol 50 (1) ◽  
pp. 318-319
Author(s):  
L.D. Schmidt ◽  
K. R. Krause ◽  
J. M. Schwartz ◽  
X. Chu
Keyword(s):  
Atmospheric Pressure ◽  
Noble Metals ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Chemical Shifts ◽  
Catalytic Converter ◽  
Structural Evolution ◽  
Single Particles ◽  
Small Metal Particles

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.

Evolution of the electronic structure of metallic multilayers from two to threedimensionality. A Full Potential Linearized Augmented Plane Wave calculation.

2002 ◽  
Vol 727 ◽  
Author(s):  
A. M. Mazzone
Keyword(s):  
Plane Wave ◽  
Density Of States ◽  
Noble Metals ◽  
Full Potential ◽  
Metallic Multilayers ◽  
Augmented Plane Wave ◽  
Narrow Bandwidth ◽  
Epitaxial Multilayers ◽  
Linearized Augmented Plane Wave ◽  
Wave Calculation

AbstractFull Potential Linearized Augmented Plane Wave calculations have been performed for epitaxial multilayers formed by the noble metals Ag and Cu with a thickness n up to 10 layers. The multilayers have a fcc lattice and are pure or compositionally modulated with a structure of the type Agn Cun or (AgCu)n. For n in the range 2,3 the density of states, evaluated at paramagnetic level, exhibits a sharp reduction of the bandwidth which is consistent with the reduced coordination of these structures. For n ≤ 5 the density of states in the central layers converges to the bulk value while the outer layers retain the narrow bandwidth found at n=2. Due to the absence of charge intermixing and hybridization, these features are shared by multilayers of all composition.

TEMPERATURE DEPENDENCE BEHAVIOR OF ELECTRICAL RESISTIVITY IN NOBLE METALS AT LOW TEMPERATURES

2014 ◽  
Vol 5 (3) ◽  
pp. 982-992 ◽  
Author(s):  
M AL-Jalali
Keyword(s):  
Experimental Data ◽  
Electrical Resistivity ◽  
Temperature Dependence ◽  
Concentration Dependence ◽  
Low Temperatures ◽  
Noble Metals ◽  
Phonon Scattering ◽  
Theoretical Models ◽  
Residual Resistivity ◽  
Electron Phonon Scattering

Resistivity temperature – dependence and residual resistivity concentration-dependence in pure noble metals(Cu, Ag, Au) have been studied at low temperatures. Dominations of electron – dislocation and impurity, electron-electron, and electron-phonon scattering were analyzed, contribution of these mechanisms to resistivity were discussed, taking into consideration existing theoretical models and available experimental data, where some new results and ideas were investigated.

Comparative evaluation of the potentiating effect of nanoparticles of noble metals in the antimicrobial compositions

2019 ◽  
pp. 5-15
Author(s):  
Konstantin I. Gurin ◽  
◽  
Valentina S. Menukhova ◽  
Ivan P. Pogorelskiy ◽  
Vladimir S. Lobastov ◽  
...  
Keyword(s):  
Comparative Evaluation ◽  
Noble Metals ◽  
Nanoparticles Of Noble Metals

Review on Methodologies Used in the Synthesis of Metal Nanoparticles: Significance of Phytosynthesis Using Plant Extract as an Emerging Tool

2020 ◽  
Vol 26 (40) ◽  
pp. 5188-5204
Author(s):  
Uzair Nagra ◽  
Maryam Shabbir ◽  
Muhammad Zaman ◽  
Asif Mahmood ◽  
Kashif Barkat
Keyword(s):  
Green Synthesis ◽  
Metal Nanoparticles ◽  
Plant Extracts ◽  
Biomedical Applications ◽  
Noble Metals ◽  
Cost Effective ◽  
Green Technology ◽  
Critical Parameters ◽  
Nanosized Particles ◽  
Preparation Methods

Nanosized particles, with a size of less than 100 nm, have a wide variety of applications in various fields of nanotechnology and biotechnology, especially in the pharmaceutical industry. Metal nanoparticles [MNPs] have been synthesized by different chemical and physical procedures. Still, the biological approach or green synthesis [phytosynthesis] is considered as a preferred method due to eco-friendliness, nontoxicity, and cost-effective production. Various plants and plant extracts have been used for the green synthesis of MNPs, including biofabrication of noble metals, metal oxides, and bimetallic combinations. Biomolecules and metabolites present in plant extracts cause the reduction of metal ions into nanosized particles by one-step preparation methods. MNPs have remarkable attractiveness in biomedical applications for their use as potential antioxidant, anticancer and antibacterial agents. The present review offers a comprehensive aspect of MNPs production via top-to-bottom and bottom-to-top approach with considerable emphasis on green technology and their possible biomedical applications. The critical parameters governing the MNPs formation by plant-based synthesis are also highlighted in this review.

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