Physical chemistry of nanostructured systems

Сентябрь 14, 2022

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Physical chemistry of nanostructured systems

Содержание

2. LECTURE No. 4 PROPERTIES OF NANOSTRUCTURED MATERIALS
3. INTRODUCTION Physical-chemistry of solid-state nanostructures is a bridge between: Atomic Physics Physical chemistry of the concentrated
4. INTRODUCTION What is Nonotechnology? What is Nonoscience? Stability: Kinetic Thermodynamic factors
5. OBJECTIVES To analyse physico-chemical properties of nanostructured materials. To explain size effect of nanoparticles on the
6. OUTLINE Physico-chemical properties of nanostructured materials. Size effect of nanoparticles on the chemical and thermodynamic properties.
7. Factors, influencing the properties of nanostructured materials (with decreasing of size of nanoparticles): A change in
8. The formation of nanoparticles from atoms is accompanied by two processes: Formation of metallic nuclei of
9. Change in the free Gibbs energy (G) Physico-chemical properties
10. Electrical resistivity Physico-chemical properties Where: - ρ∞ is the electrical resistivity of a coarse grain substance,
11. Physico-chemical properties Mechanical properties Tensile strength and hardness: Where: - is strength of a single crystal,
12. Physico-chemical properties Effect of grain size (d) on the micro hardness of metals
13. Physico-chemical properties Effect of grain size (d) on the micro hardness of metals (a) and ceramics
14. Physico-chemical properties Two-dimensional model of nanocrystalline material. Nanocrystallites with different orientations Interphase boundaries (межзеренных границ) Internal
15. Physico-chemical properties The study of experimental data and reactions of atoms, clusters and nanoparticles of various
16. Types of size effects Internal: associated with specific changes in the volume and surface properties of
17. Types of size effects The study of internal dimensional effects is aimed on the studying of:
18. The melting point as a function of the particle size and its geometry. Thermodynamic representations Where:
19. The melting point as a function of the particle size and its geometry. Vibrations of atoms:
20. The melting point as a function of the particle size and its geometry. Vibrations of atoms:
21. The melting point as a function of the particle size and its geometry. Vibrations of atoms:
22. Control questions 1. What are the main factors that influence in the properties of nanomaterials?. 2.
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LECTURE No. 4
PROPERTIES OF NANOSTRUCTURED MATERIALS

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INTRODUCTION
Physical-chemistry of solid-state nanostructures is a bridge between:
Atomic Physics
Physical chemistry

of the concentrated state

Наноструктура - очень маленький фрагмент твердого тела. Что при таких малых размерах свойства наноструктур сильно отличаются от свойств сыпучих материалов.

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INTRODUCTION
What is Nonotechnology?
What is Nonoscience?
Stability:
Kinetic
Thermodynamic factors

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OBJECTIVES
To analyse physico-chemical properties of nanostructured materials.
To explain size effect of

nanoparticles on the chemical and thermodynamic properties.

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OUTLINE
Physico-chemical properties of nanostructured materials.
Size effect of nanoparticles on the chemical

and thermodynamic properties.

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Factors, influencing the properties of nanostructured materials (with decreasing of size

of nanoparticles):
A change in the thermodynamic state of nanosystems
The appearance of quantum-size effects
excess energy and
high physico-chemical activity

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The formation of nanoparticles from atoms is accompanied by two processes:
Formation

of metallic nuclei of different sizes
Interaction between the particles, which facilitates the creation of ensembles representing nanostructures from them.

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Change in the free Gibbs energy (G)
Physico-chemical properties

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Electrical resistivity
Physico-chemical properties
Where:
- ρ∞ is the electrical resistivity of a coarse

grain substance,
- l∞ is the mean free path of electrons in a single crystal,
- q is the coefficient of electron scattering during the transition of grain boundaries (межзеренных границ)

0 < q < 1

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Physico-chemical properties
Mechanical properties
Tensile strength and hardness:
Where:
- is strength of

a single crystal,
- k is a coefficient of strength (specific for each material),
- d is an average grain size.

(Hall-Petch equation)

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Physico-chemical properties
Effect of grain size (d) on the micro hardness of

metals

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Physico-chemical properties
Effect of grain size (d) on the micro hardness of

metals (a) and ceramics (b)

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Physico-chemical properties
Two-dimensional model of nanocrystalline material.
Nanocrystallites with different orientations
Interphase

boundaries (межзеренных границ)

Internal stresses (grain boundaries as determining role)

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Physico-chemical properties
The study of experimental data and reactions of atoms, clusters

and nanoparticles of various elements of the periodic system allows us to formulate the following definition:

Pазмерные эффекты в химии – это явление, выражающееся в качественном изменении физико-химических свойств и реакционной способности в зависимости от количества атомов или молекул в частице вещества, происходящее в интервале менее 100 атомно-молекулярных диаметров.

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Types of size effects
Internal: associated with specific changes in the

volume and surface properties of both individual particles and the ensembles obtained because of their self-organization.

External: dimensionally dependent response to an external field or the action of forces independent of the internal effect.

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Types of size effects
The study of internal dimensional effects

is aimed on the studying of:
The electronic and structural properties of clusters,
The effect on chemical activity, the ionization potential, the binding energy between atoms in a particle and between particles, and
The crystallographic structure.

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The melting point as a function of the particle size and

its geometry.

Thermodynamic representations

Where:
- rs is the radius of the particle,
- ∆H is the molar latent heat of fusion,
- Υ is the surface energy,
- ρ is the density.

System dimensions are infinite.
Equilibrium and perfect crystals.

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The melting point as a function of the particle size and

its geometry.

Vibrations of atoms: Lindemann criteria.

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The melting point as a function of the particle size and

its geometry.

Vibrations of atoms: Lindemann criteria.

Where: - Tm (r) and Tm (∞) are the melting points of a nanocrystal and a compact metal,
- h the height of the monolayer of atoms in the crystal structure,
- r is the size of the nanoparticle.

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The melting point as a function of the particle size and

its geometry.

Vibrations of atoms: Lindemann criteria.

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Control questions
1. What are the main factors that influence in the properties

of nanomaterials?.
2. Mention the steps of nanostructures formation.
3. Why is important the particle size.
4. Explain the behavior of the mechanical properties with decreasing of size in nanostructured materials.
5. Describe the size effect on the melting point of nanostructured materials.
6. Analyze the models that explain the dependence of melting point on the size of metallic nanoparticles.

Physical chemistry of nanostructured systems

Содержание

LECTURE No. 4PROPERTIES OF NANOSTRUCTURED MATERIALS

INTRODUCTIONPhysical-chemistry of solid-state nanostructures is a bridge between: Atomic PhysicsPhysical chemistry

INTRODUCTIONWhat is Nonotechnology?What is Nonoscience?Stability:KineticThermodynamic factors

OBJECTIVESTo analyse physico-chemical properties of nanostructured materials.To explain size effect of

OUTLINEPhysico-chemical properties of nanostructured materials.Size effect of nanoparticles on the chemical

Factors, influencing the properties of nanostructured materials (with decreasing of size

The formation of nanoparticles from atoms is accompanied by two processes:Formation

Change in the free Gibbs energy (G)Physico-chemical properties

Electrical resistivityPhysico-chemical propertiesWhere:- ρ∞ is the electrical resistivity of a coarse

Physico-chemical propertiesMechanical propertiesTensile strength and hardness: Where: - is strength of

Physico-chemical propertiesEffect of grain size (d) on the micro hardness of

Physico-chemical propertiesEffect of grain size (d) on the micro hardness of

Physico-chemical propertiesTwo-dimensional model of nanocrystalline material. Nanocrystallites with different orientationsInterphase

Physico-chemical propertiesThe study of experimental data and reactions of atoms, clusters

Types of size effects Internal: associated with specific changes in the

Types of size effects The study of internal dimensional effects

The melting point as a function of the particle size and

The melting point as a function of the particle size and

The melting point as a function of the particle size and

The melting point as a function of the particle size and

Control questions1. What are the main factors that influence in the properties

Похожие презентации

LECTURE No. 4
PROPERTIES OF NANOSTRUCTURED MATERIALS

INTRODUCTION
Physical-chemistry of solid-state nanostructures is a bridge between:
Atomic Physics
Physical chemistry

INTRODUCTION
What is Nonotechnology?
What is Nonoscience?
Stability:
Kinetic
Thermodynamic factors

OBJECTIVES
To analyse physico-chemical properties of nanostructured materials.
To explain size effect of

OUTLINE
Physico-chemical properties of nanostructured materials.
Size effect of nanoparticles on the chemical

The formation of nanoparticles from atoms is accompanied by two processes:
Formation

Change in the free Gibbs energy (G)
Physico-chemical properties

Electrical resistivity
Physico-chemical properties
Where:
- ρ∞ is the electrical resistivity of a coarse

Physico-chemical properties
Mechanical properties
Tensile strength and hardness:
Where:
- is strength of

Physico-chemical properties
Effect of grain size (d) on the micro hardness of

Physico-chemical properties
Effect of grain size (d) on the micro hardness of

Physico-chemical properties
Two-dimensional model of nanocrystalline material.
Nanocrystallites with different orientations
Interphase

Physico-chemical properties
The study of experimental data and reactions of atoms, clusters

Types of size effects
Internal: associated with specific changes in the

Types of size effects
The study of internal dimensional effects

Control questions
1. What are the main factors that influence in the properties