Comparison of powder synthesis methods for the production of potassium sodium niobate(KNN) için kapak resmi
Comparison of powder synthesis methods for the production of potassium sodium niobate(KNN)
Pişkin, Cerem, author.
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Fiziksel Tanımlama:
x, 54 leaves: charts;+ 1 computer laser optical disc
Alkali niobate-based, i.e., potassium sodium niobate, KxNax-1NbO3 at x=0.5 (the composition at the morphotropic phase boundary (MPB)), based materials have been reported as promising lead-free piezoelectrics to be substituted with the most extensive lead-based, i.e., lead zirconate titanate (PZT) ones. In this thesis, KNN particles were obtained using three discrete powder synthesis routes: conventional solid-state reaction, hydrothermal synthesis, and sol-gel processing. The as-synthesized powders were characterized via several techniques to provide a comparative study and underline the difficulties upon KNN synthesis. In the conventional method, the phase pure K0.5Na0.5NbO3 powders were obtained at 850°C with 382 ∓ 68 nm particle size. Unfortunately, the process cannot be considered sustainable due to the high risk of nonperovskite impurity phase formations. Also, the results demonstrated that single phase KNN powder having the MPB composition could not be accomplished via a one-step hydrothermal reaction process because of the inevitable formation of the second NaNbO3 phase. Instead, post-heat treatment of biphasic (K-rich (x>0.5) KNN and NaNbO3) samples lead to induction of sodium incorporation into the crystal lattice. Eventually, phase-pure KNN particles with high proximity (x=0.58) to MPB were achieved. The KNN powder with the smallest particle size (145 nm) was obtained using the sol-gel method at 500°C. However, the samples showed carbonate impurities resulting from the reaction of unreacted alkali cations (K+ and/or Na+ ) with the ambient CO2. Hence, the KNN samples needed to be stored under an inert atmosphere to ensure purity.
Tek Biçim Eser Adı:
Thesis (Master)--İzmir Institute of Technology:Materials Science and Engineering.

İzmir Institute of Technology: Materials Science and Engineering--Thesis (Master).
Elektronik Erişim:
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Durumu/İade Tarihi
Tez T002336 QD181.N3 P677 2021

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