Alkali Niobate Powder Synthesis Using an Emerging Microwave-Assisted Hydrothermal Method

For more than five decades, alkali niobate-based materials (KxNa1−xNbO3) have been one of the most promising lead-free piezoelectric materials researched to be used in electronics, photocatalysis, energy storage/conversion and medical applications, due to their important health and environmentally f...

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Bibliographic Details
Published in:Materials 2022-08, Vol.15 (15), p.5410
Main Authors: Dumitrescu, Cristina-Rodica, Surdu, Vasile-Adrian, Stroescu, Hermine, Nicoara, Adrian-Ionut, Neacsu, Ionela Andreea, Trusca, Roxana, Andronescu, Ecaterina, Ciocan, Lucian Toma
Format: Article
Language:English
Subjects:
Electric fields
Energy consumption
Energy storage
Homogenization
Hydrothermal crystal growth
Lead free
Morphology
Niobates
Niobium oxides
Particle size
Phase transitions
Physiology
Piezoelectricity
Plasma sintering
Potassium
Radiation
Software
Solid solutions
Spectrum analysis
Structural analysis
Synthesis
Temperature
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Summary:For more than five decades, alkali niobate-based materials (KxNa1−xNbO3) have been one of the most promising lead-free piezoelectric materials researched to be used in electronics, photocatalysis, energy storage/conversion and medical applications, due to their important health and environmentally friendly nature. In this paper, our strategy was to synthetize the nearest reproductible composition to KxNa1−xNbO3 (KNN) with x = 0.5, placed at the limit of the morphotropic phase boundary (MPB) with the presence of both polymorphic phases, orthorhombic and tetragonal. The wet synthesis route was chosen to make the mix crystal powders, starting with the suspension preparation of Nb2O5 powder and KOH and NaOH alkaline solutions. Hydrothermal microwave-assisted maturation (HTMW), following the parameter variation T = 200–250 °C, p = 47–60 bar and dwelling time of 30–90 min, was performed. All powders therefore synthesized were entirely KxN1−xNbO3 solid solutions with x = 0.06–0.69, and the compositional, elemental, structural and morphological characterization highlighted polycrystalline particle assemblage with cubic and prismatic morphology, with sizes between 0.28 nm and 2.95 μm and polymorphic O-T phase coexistence, and a d33 piezoelectric constant under 1 pC/N of the compacted unsintered and unpoled discs were found.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma15155410