Abstract
The solid-state synthesis of undoped K0.5Na0.5NbO3 (KNN) and KNN doped with 1, 2 and 6 mol% Sr, from potassium, sodium and strontium carbonates with niobium pentoxide, was studied using thermal analysis and in situ high-temperature X-ray diffraction (HT-XRD). The thermogravimetry and the differential thermal analyses with evolved-gas analyses showed that the carbonates, which were previously reacted with the moisture in the air to form hydrogen carbonates, partly decomposed when heated to 200 °C. In the temperature interval where the reaction was observed, i.e., between 200 and 750 °C, all the samples exhibited the main mass loss in two steps. The first step starts at around 400 °C and finishes at 540 °C, and the second step has an onset at 540 °C and finishes with the end of the reaction between 630 and 675 °C, depending on the particle size distribution of the Nb2O5 precursor. According to the HT-XRD analysis, the perovskite phase is formed at 450 °C for all the samples, regardless of the Sr content. The formation of a polyniobate phase with a tetragonal tungsten bronze structure was detected by HT-XRD in the KNN with the largest amount of Sr dopant, i.e., 6 mol% of Sr, at 600 °C.
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References
Acmite Market Intelligence. Global piezoelectric device market, market report. Ratingen: Acmite Market Intelligence; 2014.
EU-Directive 2002/96/EC. Waste electrical and electronic equipment (WEEE). Off J Eur Union. 2003;46(L37):24–38.
EU-Directive 2002/95/EC. Restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS). Off J Eur Union. 2003;46(L37):19–23.
Rödel J, Webber KG, Dittmer R, Jo W, Kimura M, Damjanovic D. Transferring lead-free piezoelectric ceramics into application. J Eur Ceram Soc. 2015;35(6):1659–81.
Saito Y, Takao H, Tani T, Nonoyama T, Takatori K, Homma T, et al. Lead-free piezoceramics. Nature. 2004;432(7013):84–7.
Safari A, Akdogan EK, editors. Piezoelectric and acoustic materials for transducer applications. New York: Springer; 2008.
Kosec M, Kolar D. On activated sintering and electrical properties of NaKNbO3. Mater Res Bull. 1975;10(5):335–9.
Malič B, Koruza J, Hreščak J, Bernard J, Wang K, Fisher JG, et al. Sintering of lead-free piezoelectric sodium potassium niobate ceramics. Materials. 2015;8:8117–46.
Jaffe B, Cook WR, Jaffe H. Piezoelectric ceramics. London: Academic Press; 1971.
Shannon RD. Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallogr A. 1976;32(5):751–67.
Malic B, Bernard J, Holc J, Jenko D, Kosec M. Alkaline-earth doping in (K, Na)NbO3 based piezoceramics. J Eur Ceram Soc. 2005;25(12):2707–11.
Malic B, Bernard J, Holc J, Kosec M. Strontium doped K0.5Na0.5NbO3 based piezoceramics. Ferroelectrics. 2005;314:149–56.
Maeder MD, Damjanovic D, Setter N. Lead free piezoelectric materials. J Electroceram. 2004;13(1):385–92.
Acker J, Kungl H, Hoffmann MJ. Influence of alkaline and niobium excess on sintering and microstructure of sodium-potassium niobate (K0.5 Na0.5)NbO3. J Am Ceram Soc. 2010;93(5):1270–81.
Birol H, Damjanovic D, Setter N. Preparation and characterization of (K0.5Na0.5)NbO3 ceramics. J Eur Ceram Soc. 2006;26(6):861–6.
Tellier J, Malic B, Dkhil B, Jenko D, Cilensek J, Kosec M. Crystal structure and phase transitions of sodium potassium niobate perovskites. Solid State Sci. 2009;11(2):320–4.
Malic B, Jenko D, Holc J, Hrovat M, Kosec M. Synthesis of sodium potassium niobate: a diffusion couples study. J Am Ceram Soc. 2008;91(6):1916–22.
Hreščak J, Bencan A, Rojac T, Malič B. The influence of different niobium pentoxide precursors on the solid-state synthesis of potassium sodium niobate. J Eur Ceram Soc. 2013;33(15–16):3065–75.
Priya S, Nahm S, editors. Lead-free piezoelectrics. New York: Springer; 2012.
Malič B, Jenko D, Starowicz M, Bernard J, Kosec M, editors. Processing and characterization of (K, Na)NbO3 based piezoceramics. In: International conference on microelectronics, devices and materials, vol 38. Lipica, Slovenia: MIDEM—society for microelectronics, electronic components and materials; 2002.
Jenko D. Synthesis of (K, Na)NbO3 ceramics [Ph.D. thesis]. Ljubljana: University of Ljubljana; 2006.
Opravil T, Ptáček P, Šoukal F, Bartoníčková E, Wasserbauer J. Solid-state synthesis of SrY2O4 and SrSm2O4: mechanism and kinetics of synthesis, reactivity with water and thermal stability of products. J Therm Anal Calorim. 2016;123:181–94.
Arora C, Sharma A, Soni S, Naik Y, Ramarao G. Solid-state reaction of strontium oxalate with uranium oxalate: application of TG. J Therm Anal Calorim. 2016;124:43–9.
Liptay G. Atlas of thermoanalytical curves. Budapest: Akademiai Kiado; 1974.
Acknowledgements
This work was supported by the Slovenian Research Agency, under Grants P2-0105 and PR-03727. The authors would like to thank Edi Kranjc for measuring the HT-XRD of the samples.
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Hreščak, J., Malič, B., Cilenšek, J. et al. Solid-state synthesis of undoped and Sr-doped K0.5Na0.5NbO3 . J Therm Anal Calorim 127, 129–136 (2017). https://doi.org/10.1007/s10973-016-5615-3
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DOI: https://doi.org/10.1007/s10973-016-5615-3