CrystalCram

d-spacing Calculator

Crystal System

a (Å)

Active Formula

Cubic:

1d² = h²+k²+l²a²

→ d = a√(h²+k²+l²)

Bragg's Law

nλ = 2d · sin(θ)

n = reflection order
λ = X-ray wavelength
d = interplanar spacing
θ = Bragg angle

Bragg Angle Calculator

λ wavelength (Å) — CuKα = 1.5406

n (order)

Practice Mode

Exam Mode

Questions

Time Limit

Crystal Structure Parameters

Structure	Unit Cell	Atoms/Cell	APF	CN	a in terms of r	Planar Density (110)
Simple Cubic	a³	1	0.5236	6	a = 2r	12√2 a²
BCC	a³	2	0.6802	8	a = 4r√3	1√2 a²
FCC	a³	4	0.7405	12	a = 2√2 r	2√2 a²
HCP	hex	6	0.7405	12	a = 2r	—

Common Metal Lattice Constants

Metal	Structure	a (Å)	c (Å)	c/a
Cu	FCC	3.615	—	—
Al	FCC	4.050	—	—
Ni	FCC	3.524	—	—
Au	FCC	4.078	—	—
Fe (α)	BCC	2.866	—	—
W	BCC	3.165	—	—
Cr	BCC	2.884	—	—
Ti (α)	HCP	2.951	4.684	1.587
Mg	HCP	3.209	5.211	1.624
Zn	HCP	2.665	4.947	1.856

Systematic Absences (Extinction Rules)

Structure	Allowed Reflections	Example present	Example absent
SC	All (h,k,l)	(100)	none
BCC	h+k+l = even	(110), (200), (211)	(100), (111)
FCC	h,k,l all odd or all even	(111), (200), (220)	(100), (110)

Drag to rotate | Scroll to zoom

Hi! I'm the CrystalCram AI tutor. Ask me anything about crystal structures — Miller indices, lattice parameters, APF, Bragg diffraction, planar densities, extinction rules, or anything else from your materials science course.