Question

Which of the following is not a ferroelectric compound?
(a)- Rochelle’s Salt
(b)- ${{K}_{4}}[Fe{{(CN)}_{6}}]$
(c)- $BeTi{{O}_{3}}$
(d)- $K{{H}_{2}}P{{O}_{4}}$

Answer 1

Hint: Ferroelectricity is a property of certain materials in which the spontaneous electric polarization can be reversed by applying an external electric field. One of the compounds in the options is a coordination compound and this is not a ferroelectric.

Complete answer:
There are many properties of the compound in which magnetic property is one of the main properties. There are many types of magnetic properties like paramagnetic, diamagnetic, ferromagnetic, ferromagnetic, and anti-ferromagnetic.
Ferroelectricity is a property of certain materials in which the spontaneous electric polarization can be reversed by applying an external electric field. Ferroelectrics are all pyroelectric, with the added property of reversible natural electrical polarisation. The concept is analogous to ferromagnetism, which describes the presence of a permanent magnetic moment in a substance.
When Valasek discovered ferroelectricity in Rochelle salt in 1920, ferromagnetism was already known. Despite the fact that most ferroelectric materials do not contain iron, the prefix Ferro was used to characterize the property. Multiferroics are materials that are both ferroelectric and ferromagnetic.
So, in the options there are four compounds are given, i.e., Rochelle’s salt, ${{K}_{4}}[Fe{{(CN)}_{6}}]$, $BeTi{{O}_{3}}$, and $K{{H}_{2}}P{{O}_{4}}$. In these, Rochelle’s salt, $BeTi{{O}_{3}}$, and $K{{H}_{2}}P{{O}_{4}}$ show ferromagnetic properties, hence they are ferroelectric compound. But ${{K}_{4}}[Fe{{(CN)}_{6}}]$ is a coordination compound and it does not show a ferromagnetic property. Therefore, ${{K}_{4}}[Fe{{(CN)}_{6}}]$ is not a
ferroelectric compound.

Hence, the correct answer is an option (b).

Note:
Ferroelectric materials' nonlinear properties can be used to create capacitors with variable capacitance. A ferroelectric capacitor is usually made up of a pair of electrodes sandwiched between two layers of ferroelectric content. Ferroelectrics have a permittivity that is not only adjustable but also very high, particularly near the phase transition temperature.