Using an alternative production method dubbed spark plasma sintering, researchers based in the UK, Sweden and China have successfully fabricated dense nanograined BLSFs ceramics. What's more, the team has reported, for the first time, evidence that BLSFs ceramics with a grain size as small as 90 nm are still ferroelectrically active.
Ferroelectric materials are used widely in commercial products. Current applications and those under development include data storage, microwave electronic components, and micro-devices with pyroelectric and piezoelectric micro-sensors and actuators.
How small is too small?
Scientists believe that there is a fundamental change in the intrinsic properties of ferroelectrics when dimensions approach the nanoscale. From the point of view of both basic theory and practical application, an understanding of how small is too small is crucial to determine the extent to which these materials can be implemented in future generations of microelectronic structures.
Aurivillius phase, BLSFs are potential lead-free candidates for the above applications. One of the most studied compounds in the BLSFs family is Bi3.15Nd0.85Ti3O12 (BNdT). It is popular due to its high ferroelectric performances, which include high remanent polarization, fatigue resistance and low dielectric losses. To study the intrinsic size effect at the nanoscale, nanopowders have been produced by a hydrolysis method and a new processing technology called spark plasma sintering has been employed to successfully fabricate highly dense BNdT ceramics with a grain size of 90 nm.
Compared with micrograined ceramics, nanograined BNdT ceramics exhibit an enhanced dielectric constant and dramatically decreased losses at room temperature, which is interesting for microelectronics applications. An important observation is that BNdT ceramics with a grain size as small as 90 nm are still ferroelectrically active. So an interesting question arises, what is the critical size below which BLSFs ceramics are no longer ferroelectric? This is a topic of our current research.
The team presented its research in the journal Nanotechnology.