In basic crystallography, isotropic and anisotropic terms are used to explain the properties of the materials. Isotropic materials are direction independent whereas anisotropic materials are direction dependent. The differences between isotropic and anisotropic materials occur due to it's differences in the orientation of atoms in the crystals.
Below article covers the difference between isotropic and anisotropic in detail along with learning briefly about Anisotropy and Isotropy.
Table of Content
Isotropic Meaning
The materials are defined as isotropic when they do not change their properties during different crystallographic orientations. These properties can be physical, mechanical, electrical, and thermal. Isotropic materials have a single refractive index in all directions. Isotropic minerals have a Uniform composition throughout, therefore isotropic minerals have the same properties throughout. They are not direction dimension dependent. Cubic crystals such as sodium chloride and rock salt are examples of isotropic materials. These crystals are cubic and are amorphous. Cells of plants are also isotropic in nature as they are the same everywhere.
Examples of Isotropic Material
Some of the examples of isotropic materials are listed below:
- Metals such as aluminium and tungsten
- Glass
- Polymers such as plastic
- Cubic crystals such as fluorite, diamond and halite
Anisotropic Meaning
The materials are defined as anisotropic when they have atomic arrangements that are direction dependent. With different directions the physical properties of anisotropic materials changes. Except cubic crystals all other crystals are considered as anisotropic materials. Such crystals have many refractive indices. Double refraction is possible in anisotropic materials. The chemical bonding in anisotropic materials is inconsistent. These crystals are majorly used for optical applications such as optical waveplates, wedges and polarizers. The interior part of plant cells known as cytoplasm is considered as anisotropic in nature as they consists of intracellular organelles.
Examples of Anisotropic Material
Some of the examples of anisotropic material are listed below:
- Ice
- Wood
- Slate
- Crystals such as quartz and corundum
- Single crystals such as copper and nickel
Isotropic vs Anisotropic
The difference between Isotropic and Anisotropic is tabulated below:
Parameter | Isotropic | Anisotropic |
|---|---|---|
Definition | The materials are defined as isotropic when they show similar properties in all the directions. | The materials are defined as anisotropic when they show different properties in all the directions. |
Direction Dependency | Isotropic materials are direction independent. | Anisotropic materials are direction dependent. |
Number of Refractive index | Isotropic materials have only single refractive index. | Anisotropic materials have multiple refractive index. |
Chemical bonding | Chemical bonding in isotropic materials is consistent. | Chemical bonding in anisotropic materials is inconsistent. |
Velocity | Same velocity is shown by isotropic materials in all the directions. | Different velocities are shown by anisotropic materials in all the directions |
Appearance | The appearance of isotropic materials is dark. | The appearance of anisotropic materials is light. |
Double refraction | In isotropic materials double refraction is not possible. | In anisotropic materials double refraction is possible. |
Passing of Light | Light cannot pass through isotropic materials. | Light can pass through anisotropic materials. |
Applications | Isotropic materials are used in applications such as windows and lenses. | Anisotropic materials are used in applications such as polarizers, wedges, optical waveplates |
Examples | Examples of isotropic materials are metals, diamonds, crystals with cubic symmetry, glass. | Examples of anisotropic materials are all crystals except cubic crystals, wood and composite materials. |
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