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Cymbal is a class-V flextensional transducer that consists of thickness poled ceramic disc sandwiched between the two metal end caps which acts as a mechanical transformer. Cymbal transducers were fabricated using piezoceramic discs of compositions (PNS-PZT). Piezoelectric and hydrostatic constants for PNS-PZT composition were on higher side. End caps were made up of brass sheet having thickness 0.5 mm. Underwater testing of the polyurethane moulded cymbal hydrophones were carried out in acoustic tank and compared. The resonance frequency for both the hydrophones was 10.1 kHz. PNS-PZT hydrophone shows higher sensitivity (-183.2 dB re 1V/µPa) compared to PZT type 5A (-191.2 dB re 1V/µPa) at resonance frequency. Directivity pattern observed for PNS-PZT is omni-directional near resonance frequency.

EXPERIMENTAL (NiSb) 0.05 [(Zr 0.52 Ti 0.48 ) 0.995 ] 0.95 O 3 [La-PNS-PZT] was synthesised by mixed oxide route using the oxides of elements.Raw material powders NiO (97%, Acros), Sb 2 O 5 (99%, Loba Chemie), PbO (99.5%,Waldies Ltd., Kolkata), ZrO 2 (99.37%, Loba Chemie) and TiO 2 (98.5%, Travancore Titanium Products) were wet milled in pure water medium for 24 hours. Calcination was performed at 1060 °C followed by wet milling. Phase formation of the calcined powder was analysed from slow scanned X-ray diffraction pattern recorded from 42° to 58° by X-Ray diffractometer (Make -PANalytical, Model-X'pert pro). Powder was granuled using polyvinyl alcohol as a binder. Discs of diameter 29 mm and 1.7 mm thickness were compacted using double ended die punch machine (Make-GMT) by maintaining green density near to 4.8 g/cc. Samples were sintered in lead rich environment at 1270 °C for 20 min, 40 min, 60 min, 80 min and 100 min. They were lapped to 1.2 mm thickness and electroded with silver paste, followed by poling. Microstructure of polished and chemically etched samples was studied using optical microscope.Capacitance (C at 1 kHz), resonance frequency (f r ), anti (La-PNS-PZT) was optimised to achieve properties suitable for power harvesting. Composition was processed through mixed oxide route and sintered at 1270 °C for 20 min, 40 min, 60 min, 80min and 100 min. XRD pattern indicated the presence of both, ferroelectric tetragonal and ferroelectric rhombohedral perovskite phases. The optical photographs shown the uniform and dense microstructure for the samples sintered for 60 min, resulted into optimum piezoelectric charge coefficient, voltage coefficient, electromechanical coupling coefficient and figure of merit. Power harvesting capabilities in response to impact of stainless steel ball (8.25 gm) from 150 mm height were evaluated and compared with PZT type 5A. La-PNS-PZT produced batter electrical output (5.11 W, 71.13 µJ) across the matching load resistance of 4000 Ω and 2.08 W maximum power and 20.79 µJ energy by PZT type 5A disc across the matching load resistance of 1000 Ω.

Nanostructured Pb0.98La0.02(Ni1/3Sb2/3)0.05[(Zr0.52Ti0.48)0.995]0.95O3 ferroelectric ceramic has been synthesized for the first time by columbite precursor method followed by mechanical activation (MA) from 5 to 40 h of dry oxide powders using high‐energy ball mill, thereby evading the calcination stage. Progressive perovskite phase formation and transformation by MA were investigated from X‐ray diffraction (XRD) analysis, indicating the noticeable presence of perovskite phase after 10 h of milling. Particle morphology of the powder was analyzed by HRTEM and correlated with activation time. Furthermore, the effect of activation time on microstructure and piezoelectric properties of the samples sintered at 1220°C were investigated. Compact microstructure, composition at morphotropic phase boundary, optimum tetragonality, and crystallinity obtained for the sintered samples resulted in best possible piezoelectric charge coefficient, d33 (449 × 10−12 C/N), piezoelectric voltage coefficient, g33 (32 × 10−3 m.V/N), and figure of merit for power harvesting, FoMPH (14.4 × 10−12 m‐V.C/N2), for 10 h of activation. The experimental data on output voltage in response to simulated random vibrations of aerospace vehicles measured in frequency band of 20–2000 Hz were also optimum for 10 h activation, which confirm the suitability of this composition for power‐harvesting applications.

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