Difference Between Isotropic and Anisotropic

Introduction

Isotropic and anisotropic are two types of macro-scale classification.Materials are substance that constitutes an object. And they may be living or non-living things. An understanding of the properties of materials is very important. All the materials that surround us are different in many aspects that may be including their hardness, transparency, appearance, properties, etc. They are very important as it is the building block of many important things. proper classification of materials is necessary to understand more about the properties of different materials. The classification is based on many aspects such as appearance, hardness, chemical properties, and macro- scale dimension. The macro-scale classification is important among them.

What are Isotropic Materials?

The word isotropy means uniform it is formed by joining two words 'isos' which means equal and the 'tropos' which means way. If the properties of materials such as physical, chemical, thermal, and electric properties are isotropic. Metals, plastics, and glass are three materials that show isotropic behaviour.

The items present in glasses are well organized and they have similar properties in all directions. In metals, metallic bonds are formed by the sharing of electrons and their properties are the same in all directions. So isotropy means that they have uniform properties in any direction. For example, if we apply stress for any direction such as x, y, and z they will behave similarly. Several tests have been done to determine whether the properties are the same in all directions. When a force is applied to an isotropic material the effect of this force the is same in all the directions of that particular material.

Give the characteristics

The important characteristics of isotropic materials are discussed in the below points.

• Isotropic materials have the same and a constant character in all directions.

• Uniform composition is found in all the directions of isotropic material.

• They have a dark appearance in general.

• Isotropic materials do not have any optical properties.

• In all the directions the same velocity of light is shown.

• The does not split unpolarised light into two.

• They are direction independent which means properties vary in different directions.

• Only one refractive index is present.

• A constant chemical bonding is present.

• Does not show dichroism and birefringence since only one refractive index is possible.

What are Anisotropic Materials?

They are direction-dependent materials that have an unsymmetrical crystalline structure and are anisotropic. If the properties of materials such as physical, chemical, thermal, and electric properties are different in different directions are anisotropic materials. So it means that they are independent of direction. The concentration distribution or the composition of molecules are different in different directions for anisotropic materials. If a particular force is applied in an X-direction, its behaviour will be different when applied in the Y direction.

For example, wood is a good example of an anisotropic material. If a mechanical force is applied to it, the behaviour will be different in different directions. In this way, thermal, chemical, etc. properties will also vary. And is because of its asymmetric or non-uniform internal structure. Their optical properties of them are also different which means that a range of refractive indexes will be obtained by the application of a particular wavelength. All the crystals, wood, biological tissue, plant stem, and some composite materials are examples of anisotropic materials.

Give the characteristics

Some of the important characteristics of anisotropic materials are discussed in the below points.

• They have a light appearance.

• Light penetration is possible through them.

• Different chemical bonding is present in different directions because of the asymmetric composition.

• More than one refractive index is possible for them because of its different properties in different directions.

• They have different compositions in different directions.

• They show optical activity.

• Birefringence and dichroism are possible because of their more than one refractive index.

• They are directional which means that different properties are present in different directions.

• It will split unpolarised light into two.

Difference Between Isotropic And Anisotropic

Isotropic and anisotropic are two important classifications of materials based on their directional or non-directional nature. They are very distinct materials and have different properties. Some of their important difference are tabulated in the below table.

Isotropic material	Anisotropic materials
Their chemical and physical properties are direction-dependent.	Their chemical and physical properties are direction-independent.
Has only a single refractive index.	Has many refractive indexes.
The internal structure is symmetrical.	Asymmetric internal structure.
Does not have double refraction and the velocity of light is equal in all directions.	Has double refraction and the velocity of light is different in varying directions.
It appears as dark and even in the passage of light.	They appear light and allow light to enter through them.
Similar and consistent chemical bonding is present.	Dissimilar and inconsistent chemical bonding.
Used in lenses and windows.	Used in optical waveplates and polarizers.
Glass and metals are isotropic materials.	Wood and biological tissue are anisotropic materials.

Conclusion

Isotropic and anisotropic materials are two important classifications of materials. The materials in which they are direction independent are isotropic. They have the same properties in different directions. Isotropic materials have similar properties in all directions and are because of the similar chemical bonding in all directions. A very good example of isotropic material is glass, which has the same chemical composition and concentration gradient in all directions. If a force is applied, the effect of which is the same if applied in different directions too. For anisotropic materials, their properties are different in varying directions. Different chemical composition is present in different directions and so their properties are different. An important example of an anisotropic material is wood. If a force is applied the effect will be different in different directions in which the force is applied.

FAQs

1. Are crystalline solids isotropic?

Crystalline solids have a regular arrangement of molecules and atoms. They have a highly ordered arrangement of atoms and molecules. But the physical and chemical properties change in all directions. Since their properties vary in different directions they are anisotropic. So crystalline solids are anisotropic.

2. Is steel isotropic or anisotropic?

If the properties are the same in all directions it will be isotropic. And it may be homogeneous or non-homogenous. The microscopic structure of steel is non- homogenous. Even though it is non-homogenous it is isotropic, which means that all the physical, chemical, mechanical, thermal, and electrical properties are the same in all directions.

3. What is the anisotropic effect?

It means a nonuniform effect. The property in which materials have different properties in varying directions is the anisotropic effect.

4. Are all composites anisotropic?

Metals and polymers are all isotropic materials even though they are bulk materials. But composites are anisotropic materials. They have different properties in different directions.

5. Why are metals isotropic?

Electrons are shared by atoms in all directions. And the metallic bonds formed by sharing of electrons are non-directional. So the properties of metals are independent of direction. This means that they have similar properties in all directions. So metals are isotropic.