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.
Similar content being viewed by others
References
Y. Nakayama, P.J. Pauzauskie, A. Radenovic, R.M. Onorato, R.J. Saykally, J. Liphardt, P. Yang, Nature 447(7148), 1098–1101 (2007)
B. Li, Y. Hakuta, H. Hayashi, J. Supercrit. Fluids 35(3), 254–259 (2005)
V.I. Chani, K. Shimamura, T. Fukuda, Cryst. Res. Technol. 34(4), 519–525 (1999)
H. Kimura, A. Miyazaki, K. Maiwa, Z.X. Cheng, C.V. Kannan, Opt. Mater. 30(1), 198–200 (2007)
M. Mann, S. Jackson, J. Kolis, J. Solid State Chem. 183(11), 2675–2680 (2010)
M.R. Joung, H. Xu, J.S. Kim, I.T. Seo, S. Nahm, J.Y. Kang, S.J. Yoon, J. Appl. Phys. 111(11), 114314 (2012)
M.R. Joung, H. Xu, I.T. Seo, D.H. Kim, J. Hur, S. Nahm, H.M. Park, J. Mater. Chem. A 2(43), 18547–18553 (2014)
S. Chakraborty, S.K. Ghosh, G.C. Das, S. Mukherjee, Int. J. Appl. Ceram. Technol. 13(4), 743–752 (2016)
C. Huiqun, Y. Cheng, Y. Jie, C. Bo, X. Hong, Y. Bin, Rare Metal Mat. Eng. 45(6), 1391–1395 (2016)
Y. Wang, X. Kong, W. Tian, D. Lei, X. Lei, RSC Adv. 6(63), 58401–58408 (2016)
G. Shi, J. Wang, H. Wang, Z. Wu, H. Wu, Ceram. Int. 43(9), 7222–7230 (2017)
X. Kong, D. Hu, P. Wen, T. Ishii, Y. Tanaka, Q. Feng, Dalton Trans. 42(21), 7699–7709 (2013)
H. Tian, X. Meng, C. Hu, P. Tan, X. Cao, G. Shi, Z. Zhou, R. Zhang, Sci. Rep. 6(1), 25637 (2016)
Y. Purusothaman, N.R. Alluri, A. Chandrasekhar, S.J. Kim, J. Mater. Chem. C 5(22), 5501–5508 (2017)
F. Madaro, J.R. Tolchard, Y. Yu, M.A. Einarsrud, T. Grande, CrystEngComm. 13(5), 1350–1359 (2011)
D.H. Kim, M.R. Joung, I.T. Seo, J. Hur, J.H. Kim, B.Y. Kim, H.J. Lee, S. Nahm, J. Eur. Ceram. Soc. 34(16), 4193–4200 (2014)
N. Kumada, T. Kyoda, Y. Yonesaki, T. Takei, N. Kinomura, Mater. Res. Bull. 42(10), 1856–1862 (2007)
G. Pecchi, B. Cabrera, A. Buljan, E.J. Delgado, A.L. Gordon, R. Jimenez, J. Alloys Compd. 551, 255–261 (2013)
S. Kumar, L.K. Sahay, A.K. Jha, K. Prasad, Adv. Mater. Lett. 5, 67 (2013)
Acknowledgements
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy(MOTIE) of the Republic of Korea(No. 20152020104960). The authors also thank the Ku-Kist graduate school program of Korea University.
Author information
Authors and Affiliations
Corresponding author
Electronic supplementary material
ESM 1
(DOCX 1811 kb)
Rights and permissions
About this article
Cite this article
Lee, WH., Ko, YJ., Im, M. et al. Formation of a KNbO3 single crystal using solvothermally synthesized K2-mNb2O6-m/2 pyrochlore phase. J Electroceram 41, 37–42 (2018). https://doi.org/10.1007/s10832-018-0149-7
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10832-018-0149-7