Microstructural characterization of mechanically activated ZnO powders

Area of Science:

• Materials Science
• Nanotechnology
• Powder Metallurgy

Background:

• Zinc oxide (ZnO) is a versatile semiconductor with applications in electronics, catalysis, and UV protection.
• Controlling the microstructural properties of ZnO powders is crucial for optimizing their performance in various applications.
• Mechanical activation is a common technique for modifying powder characteristics.

Purpose of the Study:

• To investigate the microstructural changes in zinc oxide (ZnO) powder during mechanical activation.
• To understand the effect of milling parameters, specifically the ball-to-powder mass ratio, on ZnO powder characteristics.
• To characterize the morphology, dispersivity, and specific surface area of activated ZnO powders.

Main Methods:

• Mechanical activation of ZnO powder using a planetary ball mill under continuous regime.
• Varying the balls-to-powder mass ratio during grinding.
• Analysis of particle and agglomerate morphology and dispersivity using scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM).
• Determination of specific surface area using BET analysis.

Main Results:

• Mechanical activation introduced significant microstructural and structural defects into the ZnO powder.
• The specific surface area of ZnO powder increased from 3.60 m²/g to 4.42 m²/g after activation.
• Increased ball-to-powder mass ratio led to decreased particle dimensions and formation of compact aggregates.
• Activation produced a highly disperse, nano-scaled mixture of crystallites (10-40 nm) and aggregates (0.1-0.3 µm).

Conclusions:

• Mechanical activation effectively modifies the microstructural characteristics of ZnO powders.
• The ball-to-powder mass ratio is a critical parameter influencing crystallite and aggregate size.
• The process yields nano-scaled ZnO particles and aggregates, with potential for enhanced material properties.