Formation of a KNbO3 single crystal using solvothermally synthesized K2-mNb2O6-m/2 pyrochlore phase

Woong Hee Lee, Young Jin Ko, Mir Im, Sang Hyo Kweon, Sung Hoon Cho, Hai Bo Xu, Chong-Yun Kang, Sahn Nahm

Research output: Contribution to journalArticle

Abstract

A K2-mNb2O6-m/2 single crystal with a pyrochlore phase formed when the Nb2O5 + x mol% KOH specimens with 0.6 ≤ x ≤ 1.2 were solvothermally heated at 230 °C for 24 h. They have an octahedral shape with a size of 100 μm, and the composition of this single crystal is close to K1.3Nb2O5.65. The single-crystal KNbO3 formed when the single-crystal K2-mNb2O6-m/2 was annealed at a temperature between 600 °C and 800 °C with K2CO3 powders. When annealing was conducted at 600 °C (or with a small amount of K2CO3), the KNbO3 single crystal has a rhombohedral structure that is stable at low temperatures (< − 10 °C). The formation of the rhombohedral KNbO3 structure can be explained by the presence of the K+ vacancies in the specimen. The KNbO3 single crystal with an orthorhombic structure formed when the K2-mNb2O6-m/2 single crystal was annealed at 800 °C with 20 wt% of K2CO3.

Original languageEnglish
Pages (from-to)1-6
Number of pages6
JournalJournal of Electroceramics
DOIs
Publication statusAccepted/In press - 2018 Jul 7

Fingerprint

Single crystals
single crystals
pyrochlore
Powders
Vacancies
Annealing
Temperature
annealing
Chemical analysis
potassium carbonate
temperature

Keywords

  • KNbO
  • Metal vacancy
  • Single crystal
  • Solvothermal synthesis

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Mechanics of Materials
  • Materials Chemistry
  • Electrical and Electronic Engineering

Cite this

Formation of a KNbO3 single crystal using solvothermally synthesized K2-mNb2O6-m/2 pyrochlore phase. / Lee, Woong Hee; Ko, Young Jin; Im, Mir; Kweon, Sang Hyo; Cho, Sung Hoon; Xu, Hai Bo; Kang, Chong-Yun; Nahm, Sahn.

In: Journal of Electroceramics, 07.07.2018, p. 1-6.

Research output: Contribution to journalArticle

Lee, Woong Hee ; Ko, Young Jin ; Im, Mir ; Kweon, Sang Hyo ; Cho, Sung Hoon ; Xu, Hai Bo ; Kang, Chong-Yun ; Nahm, Sahn. / Formation of a KNbO3 single crystal using solvothermally synthesized K2-mNb2O6-m/2 pyrochlore phase. In: Journal of Electroceramics. 2018 ; pp. 1-6.
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abstract = "A K2-mNb2O6-m/2 single crystal with a pyrochlore phase formed when the Nb2O5 + x mol{\%} KOH specimens with 0.6 ≤ x ≤ 1.2 were solvothermally heated at 230 °C for 24 h. They have an octahedral shape with a size of 100 μm, and the composition of this single crystal is close to K1.3Nb2O5.65. The single-crystal KNbO3 formed when the single-crystal K2-mNb2O6-m/2 was annealed at a temperature between 600 °C and 800 °C with K2CO3 powders. When annealing was conducted at 600 °C (or with a small amount of K2CO3), the KNbO3 single crystal has a rhombohedral structure that is stable at low temperatures (< − 10 °C). The formation of the rhombohedral KNbO3 structure can be explained by the presence of the K+ vacancies in the specimen. The KNbO3 single crystal with an orthorhombic structure formed when the K2-mNb2O6-m/2 single crystal was annealed at 800 °C with 20 wt{\%} of K2CO3.",
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