Question

Explain the Synthesis of Iron Nanoparticles with its mechanism and the steps of nucleation involved in it?

Answer 1

Synthesis of Nanoparticles involves two different methods:

Physical and Chemical methods

• Physical methods involve Mechanical Milling and Laser Ablation
• Chemical methods involve Reduction method

Metal salts, Reducing Agents and Capping Agents are used in the synthesis of metal nanoparticles

Adding of Precursors leads to two possible mechanisms: Fast Nucleation and Slow Nucleation

• sodium citrate, NaBH4, Ascorbic acid are used as reducing agents for metal nanoparticle synthesis
• Thiols, Citrate and polymers such as PVA and PVP are used as Capping Agents

These Metal Nanoparticles are highly unstable

Nucleation:

• Nucleation is the phenomena where the initiation of the formation of the first crystal in the solution
• The appearance of very small particles or Nuclei of the new phase which are capable of growing
• Nucleation is of two types:

1. Homogenous Nucleation
2. Heterogeneous Nucleation

• Homogeneous Nucleation is the process where all the Nuclei form Simultaneous resulting in Monodisperese phase
• Heterogeneous Nucleation is the process where the particles Nucleate at a different time resulting in Polydisperse Phase

Strong Nucleation and slow growth is a favourable condition for the Metal Nanoparticle Synthesis

Vigorous mixing creates a Large number of Nucleation Centers

The following is the growing mechanism of size

ATOMS --> CLUSTERS --> CRYSTALLITES --> PRIMARY PARTICLES --> AGGLOMERATES

• Synthesis of Iron Nanoparticles involves Solvothermal or Hydrothermal Process, with Iron Chloride as the main raw material along with reducing and capping agents.
• Iron chloride + Trisodium Citrate + Sodium Acetate are used along with Ethylene Glycol in the synthesis of Fe Nanoparticles

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