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Ferroelectrics - why?

We have now seen how ferroelectrics behave and why they behave in this way. The question to ask now is ‘So what?’. The answer is simple. Ferroelectrics are very useful for devices and are used in many different ways today. If a ferroelectric is used in its linear region, above TC it makes a very good capacitor, as its dielectric constant can be very high indeed. These are often used in cameras as a way of powering a flash. A battery slowly stores a charge on a capacitor, which when connected to a bulb, releases a burst of high current, creating the flash.

First, the battery charges the ferroelectric capacitor and then, once fully charged, the ferroelectric is connected to the bulb and causes it to flash.

Note: This animation requires Adobe Flash Player 8 and later, which can be downloaded here.

Ferroelectrics are also being considered as a form of non-volatile computer memory, FeRAM (Ferroelectric Random Access Memory). Here, a ferroelectric can be in one polarised state or another, which can act as a 0 or 1, allowing use as binary.

Image of hysteresis loop

The two states may be distinguished by cycling the charge. They store non-volatile data, i.e. data even when the power is switched off. However, this is not as fast as current DRAM structures, so it is still under development, but it is actually used in e.g. the Sony Playstation 2, because a range of considerations permit it to fulfil this role.


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