Synthesis of KNbO3 nanostructures by a microwave assisted hydrothermal method

Ueno

Trans. Mat. Res. Soc. Japan

2015

The present work describes the preparation of potassium niobate (KNbO 3 ) nanocrystals by wet chemical reaction at low temperature. Nanocube is particularly paid attention in dielectric materials. The KNbO 3 have perovskite structure and indicate ferroelectrics property. In this study, preparation of the KNbO 3 nanocubes was investigated using solvothermal and microwave reactions. Microwave method enable to the rapidly increasing temperature. 40 mL ethanol was used as reaction medium while 1 mmol niobium oxide (Nb 2 O 5 ) and 10 mmol potassium hydroxide (KOH) were used as raw materials. The microwave-assisted solvothermal reaction was carried out at 200℃ for 30 minutes. Then, solvothermal reaction was performed at 230℃ for 18 h. The characterization was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). KNbO 3 was not obtained from the XRD measurement after the microwave-assisted solvothermal reaction at 200℃ for 30 minutes. However, the main XRD peaks indicated KNbO 3 after solvothermal reaction at 230℃ for 18 h. The shape of obtained powders was nanocube from SEM observation. That is to say, KNbO 3 nanocubes were obtained by combining microwave and solvothermal reactions.

Section: Introductionmentioning

confidence: 99%

Preparation of Potassium Niobate Nanocrystals by Wet Chemical Reaction at Low Temperature

Ueno

Trans. Mat. Res. Soc. Japan

2015

“…The merit of the wet chemical reaction is shape and size control of obtained powders. In particular, there are many reports of powders preparation of unique shape by means of hydrothermal method, glycothermal method, and microwave-assisted process [2][3][4][5]. Hydrothermal synthesis is the use of aqueous solvents under the high temperature and high pressure in an autoclave and it could produce the crystallization.…”

Section: Introductionmentioning

confidence: 99%

“…Also, they described the adjusting the reaction temperature and the potassium hydroxide (KOH) / niobium oxide (Nb 2 O 5 ) ratio. Regarding the microwave-assisted hydrothermal method, Paula et al reported the synthesis of single-crystalline KNbO 3 particles [3]. This method made possible a very fast synthesis of single crystalline powders.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Characterization of KNbO<sub>3</sub> Nanocubes under Various Solvothermal Conditions

Ueno

Trans. Mat. Res. Soc. Japan

2014

Potassium niobate (KNbO 3 ) is a perovskite oxide functional material that has been attracting attention as dielectric materials. The present work describes the fabrication of the KNbO 3 nanocubes by wet chemical reaction. The preparation and characterization of the KNbO 3 nanocubes were investigated. KNbO 3 was prepared using a solvothermal method. 40 mL organic solvent was used such as methanol, ethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, and 2-(2-n-butoxyethoxy)ethanol while niobium oxide (Nb 2 O 5 ) and potassium hydroxide (KOH) were used as raw materials. The reaction was performed at 230 -250℃ for 18 h. The characterization was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). When solvothermal syntheses were performed with various organic solvents, KNbO 3 was formed from the XRD measurement and KNbO 3 nanocubes were obtained from SEM observations. Particularly, KNbO 3 nanocubes were the smallest size when the methanol solvent was used in this study.

“…4) 7) In 2007, three types of KNbO 3 powders with orthorhombic, tetragonal, and cubic symmetries were synthesized by Kumada et al using a hydrothermal reaction, by adjusting the reaction temperature and the potassium hydroxide (KOH)/niobium oxide (Nb 2 O 5 ) ratio. 4) In 2008, Paula et al reported the synthesis of single-crystalline KNbO 3 particles through the reaction of Nb 2 O 5 and KOH via a microwave-assisted hydrothermal method. 5) In 2011, Kaseda et al demonstrated that fine particles of KNbO 3 could be synthesized on a time scale of seconds in supercritical water using a flow reactor.…”

Section: Introductionmentioning

confidence: 99%

“…4) In 2008, Paula et al reported the synthesis of single-crystalline KNbO 3 particles through the reaction of Nb 2 O 5 and KOH via a microwave-assisted hydrothermal method. 5) In 2011, Kaseda et al demonstrated that fine particles of KNbO 3 could be synthesized on a time scale of seconds in supercritical water using a flow reactor. 6) Liquid reaction processes have the advantage of allowing control of morphology.…”

Section: Introductionmentioning

confidence: 99%

Preparation of KNbO<sub>3</sub> nanocubes using a solvothermal method at low temperature

Fujii

2013

J. Ceram. Soc. Japan

Potassium niobate (KNbO 3 ) was prepared using a solvothermal method. The synthesis was conducted using niobium oxide (Nb 2 O 5 ) and potassium hydroxide (KOH) as starting materials and ethanol as the reaction medium. X-ray diffraction (XRD) confirmed the presence of perovskite KNbO 3 particles and indicated that the lattice of the KNbO 3 was orthorhombic. The morphology of the KNbO 3 was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM). Energy-dispersive X-ray (EDX) spectrometry was conducted with TEM/STEM, which clearly revealed that the KNbO 3 particles were nanosized and possessed a cubic shape with sharp-edged corners. The STEM-EDX observations indicated that all three elements of potassium (K), niobium (Nb), and oxygen (O) were distributed homogeneously across the nanocubes. Only K, Nb, and O were detected in the EDX spectrum of the KNbO 3 powders obtained. Thus, KNbO 3 nanocubes were successfully prepared using a solvothermal method at low temperature.