Atomic Packing Factor Formula:
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Definition: Atomic Packing Factor (APF) is the fraction of volume in a crystal structure that is occupied by constituent particles.
Purpose: It helps materials scientists and engineers understand the efficiency of atomic arrangement in crystalline materials.
The calculator uses the formula:
Where:
Explanation: The formula calculates what fraction of the unit cell's volume is actually occupied by atoms.
Details: APF helps predict material properties like density, strength, and thermal conductivity. Higher APF typically indicates more densely packed structures.
Tips: Enter the number of atoms in the unit cell, volume of each particle (default 1×10⁻²⁹ m³), and volume of unit cell (default 1.05×10⁻²⁸ m³). All values must be > 0.
Q1: What is a typical APF value?
A: For simple cubic it's 0.52, BCC 0.68, FCC and HCP 0.74.
Q2: How do I find the number of atoms in a unit cell?
A: Count all atoms fully within the cell plus fractions of atoms at edges/corners.
Q3: What units should I use?
A: Use consistent units (typically cubic meters) for both particle and unit cell volumes.
Q4: Can APF be greater than 1?
A: No, APF is a fraction of space occupied and cannot exceed 1.
Q5: How does APF relate to material density?
A: Higher APF generally means higher density, assuming similar atomic weights.