Neutral ceramics can be polarised by physical stress. If a permanent polarisation is required then an electric field is applied during manufacture. The key term that is missing is " electret ".nabs16 said:Ferroelectric materials have spantaneous polarization but i read in many articles that these ceramics are polarized by applying an electric field. Why polarize ceramics that are already polarized ?
Ferroelectric materials are a type of crystalline material that exhibit spontaneous electric polarization, meaning they have a dipole moment even in the absence of an external electric field. Piezoelectric materials, on the other hand, generate an electric charge when subjected to mechanical stress or pressure.
Ferroelectric materials are often used in memory devices, such as ferroelectric random access memory (FeRAM) and ferroelectric non-volatile random access memory (FRAM). Piezoelectric materials are commonly used in sensors, actuators, and transducers, such as in ultrasound machines, pressure sensors, and speakers.
Yes, some materials exhibit both ferroelectric and piezoelectric properties. These materials are known as ferroelectric piezoelectric materials and are commonly used in applications that require both properties, such as in ultrasound transducers and piezoelectric motors.
Ferroelectric materials have a hysteresis loop in their polarization-electric field curve, meaning their polarization can be reversed by applying an external electric field. In contrast, piezoelectric materials have a linear relationship between their strain and the applied electric field, meaning their response is reversible and directly proportional to the strength of the applied field.
The main advantage of using ferroelectric materials is their ability to retain a stable polarization state, making them useful for non-volatile memory applications. Piezoelectric materials, on the other hand, have a higher sensitivity and can generate a larger electric charge, making them better suited for sensing and actuation applications.