The key difference between paramagnetic and diamagnetic materials is that the paramagnetic materials get attracted to external magnetic fields whereas the diamagnetic materials repel from the magnetic fields.
Materials tend to show weak magnetic properties in the presence of an external magnetic field. Some materials get attracted to the external magnetic field, whereas some repel from it. Due to this difference in magnetic behaviour, we can categorize elements and compounds into two types, namely paramagnetic and diamagnetic. Materials that get attracted to external magnetic fields are the paramagnetic materials. On the other hand, the materials that repel from external magnetic fields are the diamagnetic materials.
CONTENTS
1. Overview and Key Difference
2. What is Paramagnetic
3. What is Diamagnetic
4. Side by Side Comparison – Paramagnetic vs Diamagnetic in Tabular Form
5. Summary
What is Paramagnetic?
Paramagnetism occurs due to the presence of unpaired electrons in the system. Each element has a different number of electrons, and that defines its chemical character. According to how these electrons fill into the energy levels around the nucleus of the respective atom, some electrons remain unpaired. These unpaired electrons act like little magnets causing magnetic properties under the influence of an externally applied magnetic field. Actually, it’s the spin of these electrons that causes magnetism.
Paramagnetic materials have permanent dipole magnetic moments due to the spin of the unpaired electrons even during the absence of an external magnetic field. But these dipoles orient themselves randomly due to thermal motion hence giving a zero net dipole magnetic moment. When we apply an external magnetic field, the dipoles tend to align in the direction of the applied magnetic field resulting in a net dipole magnetic moment. Therefore, paramagnetic materials slightly get attracted to the external magnetic field. But, the material does not retain magnetic properties once we remove the external field. Only a small induced magnetization creates even in the presence of an external magnetic field. This is because, only a small fraction of spins orients with the external magnetic field. Also, this fraction is directly proportional to the strength of the field created.
Figure 01: Electron arrangement of Paramagnetic and Diamagnetic Materials
Generally, the higher the number of unpaired electrons, higher the paramagnetic behaviour and higher the strength of the field created. Therefore, transition and inner transition metals show stronger magnetic effects due to the localization of ‘d’ and ‘f’ electrons and also due to the presence of multiple unpaired electrons. Some commonly known paramagnetic elements include Magnesium, Molybdenum, Lithium, and Tantalum. There are also stronger synthetic paramagnets such as ‘ferrofluids’.
What is Diamagnetic?
Some materials tend to show a repelled magnetic behaviour when put in contact with an external magnetic field. These are the diamagnetic materials. They create magnetic fields that are opposing in the direction of the external magnetic field and hence show the repelling behavior. Generally, all materials have the diamagnetic properties, making a weak contribution to the magnetic behaviour of the material when subjected to an external magnetic field. But, in materials that show other magnetic properties such as paramagnetism and ferromagnetism, the effect of diamagnetism is negligible. Due to its weak magnetic property, the effects of diamagnetism is difficult to observe. ‘Bismuth’ acts as a strong diamagnet.
What is the Difference Between Paramagnetic and Diamagnetic
The term paramagnetic refers to the attraction of a material to an external magnetic field while the term diamagnetic refers to the repulsion of a material from an external magnetic field. This is mainly because the paramagnetic materials have unpaired electrons whereas diamagnetic materials have none of their electrons unpaired. This is the fundamental difference between paramagnetic and diamagnetic materials.
Another important difference between paramagnetic and diamagnetic materials is that the magnetic field created by paramagnetic materials is in the direction of the external magnetic field while the magnetic field created by diamagnetic materials is opposing in a direction to the external magnetic field.
The below infographic shows a comparison summary of the difference between paramagnetic and diamagnetic materials.
Summary – Paramagnetic vs Diamagnetic
We can divide the materials into three major types according to their magnetic properties; they are, diamagnetic, paramagnetic and ferromagnetic materials. The difference between paramagnetic and diamagnetic materials is that the paramagnetic materials get attracted to the external magnetic fields whereas the diamagnetic materials repel from the magnetic fields.