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Updated: Sep 1, 2025
Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area
Published on: February 19, 2018
Alkali Niobate Powder Synthesis Using an Emerging Microwave-Assisted Hydrothermal Method
Cristina-Rodica Dumitrescu1, Vasile-Adrian Surdu1,2, Hermine Stroescu3
1Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Chemical Engineering and Biotechnologies, University Politehnica of Bucharest, 060042 Bucharest, Romania.
Researchers synthesized lead-free alkali niobate (KNN) powders near the morphotropic phase boundary using hydrothermal microwave-assisted maturation. The resulting KNa1-NbO3 solid solutions exhibited polymorphic phase coexistence and sub-nanometer to micrometer particle sizes.
Area of Science:
- Materials Science
- Solid State Chemistry
- Nanotechnology
Background:
- Alkali niobate (KNN) materials are promising lead-free piezoelectric alternatives.
- Their applications span electronics, energy, and medical fields due to environmental benefits.
- Achieving optimal properties requires precise control over composition and phase structure.
Purpose of the Study:
- To synthesize reproducible potassium sodium niobate (KNN) powders near the morphotropic phase boundary (MPB).
- To investigate the effects of hydrothermal microwave-assisted maturation (HTMW) parameters on KNN synthesis.
- To characterize the resulting KNN solid solutions for compositional, structural, and morphological properties.
Main Methods:
- Wet synthesis route involving Nb2O5 powder and alkaline solutions (KOH, NaOH).
- Hydrothermal microwave-assisted maturation (HTMW) at 200-250 °C, 47-60 bar, for 30-90 min.
- Compositional, elemental, structural, and morphological characterization of synthesized powders.
Main Results:
- Successfully synthesized KNa1-NbO3 solid solutions with compositions ranging from x = 0.06 to 0.69.
- Observed polycrystalline particle assemblages with cubic and prismatic morphologies (0.28 nm–2.95 μm).
- Confirmed polymorphic orthorhombic-tetragonal (O-T) phase coexistence and low piezoelectric constant (d33 < 1 pC/N).
Conclusions:
- The HTMW method enables the synthesis of KNN solid solutions near the MPB.
- The synthesized KNN powders exhibit phase coexistence and controlled morphology.
- Further optimization is needed to enhance the piezoelectric properties for practical applications.
