Miller Indices Calculator - Cubic crystals (2024)

The Miller indices calculator determines the interplanar distance for cubic crystal systems. It was introduced in 1839 by a British mineralogist named Prof. William Hallowes Miller. Miller indices are part of X-ray crystallography, which are useful to study the optical properties of atoms (cf. atom calculator) and molecules using their crystal structures.

In addition to the optical properties, it is also helpful to observe dislocations during the plastic deformations in an atomic structure, i.e., the strain at the atomic level. The knowledge is crucial in nanofabrication or machining nano wafers. There are different kinds of crystal lattices; this calculator focuses on cubic structures in particular.

The topic is a fundamental concept in material sciences that has implications in various fields. This article will help you understand the definition of Miller indices and the steps on how to calculate Miller indices.

The Miller indices represent the reciprocal of the intercepts a [plane makes with each axis. In a 3-dimensional plane, consider a crystal face parallel to the XY plane. The intercepts for the crystal face with the axes are $(\infin, \infin, 1)$(∞,∞,1). Therefore, the Miller indices for the face are $(1/\infin, 1/\infin, 1) = (100)$(1/∞,1/∞,1)=(100).

If the intercepts are fractions, the indices are converted to integers by multiplying by their common denominator. The negative intercepts are represented with a bar on the index.

Using the Miller indices and the lattice constant, you can determine the interplanar distance for the unit cell. Mathematically, this is:

where:

• $h,k,l$h,k,l – Miller indices;
• $a$a – Lattice constant; and
• $d_{hkl}$dhkl​ – Interplanar distance.

To calculate Miller indices using this calculator:

1. Locate the x, y, and z axes intercept for the crystal face.
2. Find the reciprocal of the intercept to obtain the Miller indices.
3. Enter the lattice constant for the cubic cell.
4. Fill in the Miller indices, $(hkl)$(hkl).
5. The Miller indices calculator will return the interplanar distance for the cubic cell.

Find the interplanar distance for a cubic unit cell having Miller indices (201) and lattice constant $2\r{\text{ A}}$2A˚.

1. Enter the lattice constant for the cubic cell as $2\r{\text{ A}}$2A˚.
2. Fill in the Miller indices as 2, 0 and 1, respectively.
3. The interplanar distance, $d_{hkl}$dhkl​ is:

To determine the Miller indices:

1. Find the x, y, and z intercepts for the face.
2. Calculate the reciprocal of the intercepts to obtain the Miller indices.

In the case of the Miller indices being fractions, multiply the index with the common denominator to convert them into integers.