Isotropic and Anisotropic

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.

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.

FAQs on Isotropic vs Anisotropic

1. What is Isotropic?

Isotropic is the property of material in which the physical properties such as refractive index etc. are direction independent.

2. What is Anisotropic?

Anisotropic is the property of material due to which the values of the physical properties become direction dependent i.e. have different values in different ditrection.

3. Why Sodium Chloride is known as Isotropic?

Sodium Chloride is known as isotropic because of its cubic like crystal structure. Sodium Chloride has same symmetry along its all the three axes therefore it it posses same properties in all the directions.

4. Why Anisotropic are considered more better than Isotropic?

Anisotropic and isotropic both are different in terms of strength. Anisotropic materials have stronger magnetic properties as compared to isotropic materials hence anisotropic materials are more direction dependent.

5. Where are Anisotropic Materials used?

Anisotropic materials are used in various applications such as medicine for medical ultrasound imaging and materials used for conduction and rejection of heat.

6. Which tissues in Human Body Anisotropic?

Soft tissues in human body such as skeletal muscles, skin and tissues that forms organs such as brain and myocardial tissues are anisotropic in nature.

7. Can light pass through Isotropic Materials?

No, light cannot pass through isotropic materials because they have only one refractive index. Therefore double refraction is also not possible through isotropic materials.