Research Projects

The emergence of Industry 4.0 has led to the rapid proliferation of Internet of Things (IoT) devices across a wide range of applications, including healthcare monitoring systems, defense surveillance, industrial automation, smart homes, environmental sensing, and infrastructure management. These devices typically operate on low power (10–100 μW) and rely on batteries for energy. However, the extensive use of batteries presents significant environmental concerns related to their limited lifespan, high replacement costs, hazardous chemical composition, and disposal issues, which collectively contribute to electronic waste accumulation. To overcome these limitations and ensure long-term sustainability, piezoelectric energy harvesters (PEHs) have gained attention as a promising alternative to battery-based powering systems. PEHs convert mechanical vibrations (ambient or induced) into electrical energy using the direct piezoelectric effect. Among various piezoelectric materials, lead-based ceramics such as Pb(Zr,Ti)O₃ (PZT) and Pb(Mg₁/₃Nb₂/₃)O₃-PbTiO₃ (PMN-PT) are most commonly employed due to their superior piezoelectric properties (d₃₃ 300–600 pC/N). However, these materials pose serious health and ecological hazards owing to their high lead content (60 wt%) and the volatility of PbO during high-temperature processing. Their use is being increasingly restricted by global environmental directives such as RoHS (Restriction of Hazardous Substances), WEEE (Waste Electrical and Electronic Equipment), and ELV (End-of-Life Vehicles). In response to these challenges, the present project aims to develop eco-friendly, high-performance, lead-free piezoelectric ceramics that can serve as sustainable power sources for IoT systems. The proposed materials are based on perovskite-type ABO₃ compounds, including BaTiO₃ (BT), (Bi₁/₂Na₁/₂)TiO₃ (BNT), and (Na,K)NbO₃ (KNN), which are lead-free and exhibit intrinsic ferroelectric and piezoelectric properties. However, in their conventional polycrystalline form, these materials often suffer from low Curie temperatures (Tc), weak poling efficiency, low mechanical quality factors, and poor temperature stability. To address these limitations, the project proposes a composition- and microstructure-driven approach using domain engineering and Templated Grain Growth (TGG) to fabricate textured (grain-oriented) piezoceramics. Texturing aligns the crystallographic orientations of grains to mimic single-crystal behavior, significantly enhancing piezoelectric response and energy conversion efficiency. The novelty lies in achieving single-crystal-like properties (d₃₃ ~250 pC/N, Tc ~150 °C) using cost-effective tape casting and TGG techniques as opposed to expensive and time-consuming single-crystal growth. The methodology involves: • Solid-state synthesis of BT, BNT, and KNN compositions. • Doping strategies (e.g., Ca, Zr, Sn) to optimize morphotropic/polymorphic phase boundaries (MPB/PPB). • Synthesis of template particles using molten salt routes for orientation control. • Tape casting and sintering to induce texture using TGG or RTGG. • Structural (XRD, SEM, TEM), electrical (dielectric, piezoelectric), and functional (energy harvesting output) characterization. • Fabrication of vibration energy harvesting prototypes (unimorph/bimorph structures). The expected outcomes include: • Development of lead-free piezoceramics with competitive performance compared to PZT. • Demonstration of vibration-powered energy harvester prototypes for powering small-scale IoT devices. • Advancement of fundamental understanding in piezoceramic texturing and transduction behavior. • Contribution to India’s green energy goals and Industry 4.0 infrastructure with sustainable technology. This research not only aligns with national missions like Make in India and Digital India but also contributes globally to the shift toward sustainable electronics by offering an environmentally responsible alternative to toxic PZT-based piezoceramics.