Speaker and Affliation:
Dr. Ajeet Kumar
School of Materials Science and Engineering,
16th December, 2021 (Thursday), 02:30 PM (India Standard Time)
The thin/thick films of ferroelectrics (FE) have a wide range of applications. However, high processing/annealing temperature (≥600°C) involved in the fabrication of thin/thick films causes the electrical breakdown of the films and also prevents their deposition on flexible, and metallic substrates. The thin/thick films of ferroelectrics at lower temperatures can be fabricated by (1) laser-induced crystallization (LIC) technique using an excimer laser (<300oC) (2) aerosol deposition (AD) method at room temperature and (3) photon-assisted flash annealing technique. We have successfully demonstrated a way to crystallize Ba0.5Sr0.5TiO3 (BST) thin films at a lower temperature of ~300°C by an alternating depositing and annealing process using the pulsed laser deposition (PLD) method. At first, the BST thin film with a thickness of ~120 nm was deposited (laser energy of ~2 J/cm2) and subsequently laser annealed (66 mJ/cm2) at 300°C with several repetitions. Similarly, the aerosol deposition (AD) technique was employed to fabricate the thick films of PLZT ceramics (relaxor and anti-ferroelectric) at room temperature. The grain sizes of the AD thick films were tuned by thermal annealing which in turn can tune the electrical properties. The PLZT AD thick films showed excellent energy-storage density with stable energy efficiency which is required for commercial applications. Recently, photonics-based annealing using a xenon flash lamp has been successfully demonstrated for the annealing of metal oxide films on metal or polymer substrates fabricated by using PLD and AD. This photon-assisted flash annealing technique can be employed to realize flexible triboelectric/piezoelectric nanogenerators, magneto-mechano-electric (MME) generators, magnetic field sensors, micro-electro-mechanical-systems (MEMS), and micro-actuators.