Origin of the polarization in BaTiO3 unit cell

In summary, in perovskite crystals like BaTiO3, the off-center position of the Ti ion results in a polarization moment within the unit cell. This does not necessarily lead to a separation of the electron cloud from the nuclei of the Ti atom, as the Ti atom itself is in a 4+ state, causing the entire unit cell to acquire a dipole moment. The dipole moment can be calculated for both a perfectly symmetric and a distorted unit cell, considering the atoms as charged points. The Ti atom is in a 4+ state in both cases.
  • #1
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hi, in perovskite crystal, such as BaTiO3, due to the off-centre of Ti ion, there exists a polarization moment in the unit cell (as shown in below link). my question is: does the disposition of Ti atom lead to separation of electron cloud from the nuclei of the Ti atom and so the Ti atom plays as a electric dipole ?

https://www.comsol.com/blogs/piezoelectric-materials-crystal-orientation-poling-direction/

Perovskite-unit-cell.png
 
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  • #2
Not really. The Ti atom itself is in the 4+ state so that the whole unit cell acquires a dipole moment. You should probably look up the definition of the dipolar moment and calculate it for a perfectly symmetric and a distorted unit cell. Just think of the atoms as charged points. It is really that simple.
 
  • #3
so if the dipole moment of the unit cell is because the Ti atom is in 4+ state. So when is the Ti atom in the 4+ state ? for a perfectly symmmetric cell or distorted cell ?
 

What is the origin of polarization in BaTiO3 unit cell?

The origin of polarization in BaTiO3 unit cell is due to the displacement of positive and negative ions in the crystal structure.

How does the displacement of ions lead to polarization in BaTiO3 unit cell?

The displacement of positive and negative ions creates an electric dipole moment, resulting in a net polarization in the unit cell.

Is the polarization in BaTiO3 unit cell permanent?

The polarization in BaTiO3 unit cell is not permanent and can be reversed by applying an external electric field.

What role does the crystal structure play in the polarization of BaTiO3 unit cell?

The unique crystal structure of BaTiO3 allows for the displacement of ions and leads to the creation of a net polarization in the unit cell.

Can the polarization in BaTiO3 unit cell be controlled?

Yes, the polarization in BaTiO3 unit cell can be controlled by applying an external electric field, changing the temperature, or altering the crystal structure through doping or strain.

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