Synthesis and study on piezoelectric and acoustic properties of pure and doped PZT nanostructure for use in sensore

نوع: Type: thesis

مقطع: Segment: PHD

عنوان: Title: Synthesis and study on piezoelectric and acoustic properties of pure and doped PZT nanostructure for use in sensore

ارائه دهنده: Provider: Fatemeh Yousefi

اساتید راهنما: Supervisors: Dr. Hamid Esfahani

اساتید مشاور: Advisory Professors: Dr. Hamid Reza Karami

اساتید ممتحن یا داور: Examining professors or referees: Dr:Akbar Heydarpure-Mehdi Kazazi-Hasan Elmkhah

زمان و تاریخ ارائه: Time and date of presentation: 2024

مکان ارائه: Place of presentation: Faculty of Engineering

چکیده: Abstract: Today, acoustic sensors play a very important role in detecting damage in structures (SHM) before destruction occurs. In addition, acoustic sensors play a significant role in the development of acoustic energy harvesters (AEH) from sources of sound waste such as noises in traffic, stadiums, train stations, etc. With the introduction and development of nanostructured materials based on lead zirconate titanate (PZT), this can be done more efficiently. In the present research in three phases; 1- Synthesis of pure PZT nanostructures and Doped with Nb and Nd by electrospinning and calcination method, 2- Acoustic behavior of flexible polyvinylidene fluoride (PVDF) scaffolds containing nanostructures and 3- The role of non-stoichiometric PZT nanostructures on acoustic energy harvesting PVDF flexible scaffolds, the mentioned goals are investigated. By doping Nb and Nd individually and simultaneously in Pb(Zr0.52Ti0.48)O3, smooth and flawless fibers with average fiber diameter of 292 ± 82 nm were synthesized after electrospinning. After calcination, the fibers were transformed into nanowhiskers. The simultaneous contamination of Nb and Nd not only led to an increase in the l/d ratio of the whisker, but also the most structural disorder and composition close to the morphotropic boundary (MPB), which is the reason for observing the highest dielectric behavior (21642), piezoelectric sensitivity (mV/ N 69/7) and magnetism (Oe 492), it was obtained. Also, studies showed that Nb tends to form Zr-rich PZT (rhombohedral structure) and Nd tends to form Ti-rich PZT (tetragonal structure). In the second phase, using the electrospinning method, pure and doped PZT nanostructures were synthesized inside or as clusters connected to fibers in the PVDF scaffold. The results showed that the simultaneous contamination of Nb and Nd led to the greatest increase in the β phase (79.8%) in the PVDF structure, which resulted in piezoelectric sensitivity (1.071 mV/N). By examining the acoustic behavior of the scaffolds, including sound absorption coefficient (α) and noise reduction coefficient (NRC), it was found that PZT nanostructures doped simultaneously with Nb and Nd have the greatest effect on sound absorption. Therefore, in the third phase of the research, non-stoichiometric PZT nanostructures (contaminated with Nb and Nd simultaneously) were used as nano generators (PENG) in the AEH behavior of PVDF-based flexible scaffolds. By changing the amount of PENG (x equal to 2.5, 5 and 10% by weight), the morphology of the fibers changed. At x=2.5, a homogeneous distribution of nanostructures inside the fibers was observed. Also, the maximum β phase, the maximum piezoelectric sensitivity (V/N 1.95) and magnetism (Oe 750) and the lowest surface resistance (1.2 kΩ/sq) of the scaffold were observed at this value. Examining the results of the acoustic energy harvesting process showed that the highest output power density (0.0822 W/g) at a sound pressure of 90 dB and a frequency of 2000 Hz by a flexible PVDF scaffold containing 2.5% by weight of non-stoichiometric PZT nanostructures (doped with Nb and Nd simultaneously) can be extracted. According to the findings of this research, non-stoichiometric PZT nanostructures can be suggested as an effective factor in sound sensors and acoustic energy harvester

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