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Grain-size-induced ferroelectricity in NaNbO3

Koruza, Jurij ; Groszewicz, Pedro B. ; Breitzke, H. ; Buntkowsky, G. ; Rojac, Tadej ; Malič, Barbara :
Grain-size-induced ferroelectricity in NaNbO3.
In: Acta Materialia (126) pp. 77-85.
[Artikel], (2017)

Kurzbeschreibung (Abstract)

The influence of a material's length scale on its functional properties has been reported for many ferroics, where a decrease in the dielectric, ferroelectric, and piezoelectric properties is frequently observed when the size is reduced below the micrometer range. Here we demonstrate that in NaNbO3, in contrast to general expectations, a long-range ferroelectric order is induced when decreasing the size. A series of sintered, polycrystalline, NaNbO3 samples with different grain sizes was prepared and analyzed using differential scanning calorimetry, dielectric measurements, and 23Na 3QMAS nuclear magnetic resonance(NMR). A size-induced phase transition into the ferroelectric polymorph was observed when the grain size decreased below 0.27 mm. The different polymorphs were distinguished based on the local symmetry of the Na(1) sodium site. NMR was also used to determine the relative amounts of the polymorphs in the samples. The observed size-induced phase transition is attributed to the existence of intragranular stresses, induced by the decreased compensation of the ferroelastic energy during the formation of non- 180° domainwalls when decreasing the grain size and the large anisotropy of the thermal expansion. The results demonstrate the unique possibility of stabilizing ferroelectricity by reducing the grain size, which was not observed in other ferroic systems.

Typ des Eintrags: Artikel
Erschienen: 2017
Autor(en): Koruza, Jurij ; Groszewicz, Pedro B. ; Breitzke, H. ; Buntkowsky, G. ; Rojac, Tadej ; Malič, Barbara
Titel: Grain-size-induced ferroelectricity in NaNbO3
Sprache: Englisch
Kurzbeschreibung (Abstract):

The influence of a material's length scale on its functional properties has been reported for many ferroics, where a decrease in the dielectric, ferroelectric, and piezoelectric properties is frequently observed when the size is reduced below the micrometer range. Here we demonstrate that in NaNbO3, in contrast to general expectations, a long-range ferroelectric order is induced when decreasing the size. A series of sintered, polycrystalline, NaNbO3 samples with different grain sizes was prepared and analyzed using differential scanning calorimetry, dielectric measurements, and 23Na 3QMAS nuclear magnetic resonance(NMR). A size-induced phase transition into the ferroelectric polymorph was observed when the grain size decreased below 0.27 mm. The different polymorphs were distinguished based on the local symmetry of the Na(1) sodium site. NMR was also used to determine the relative amounts of the polymorphs in the samples. The observed size-induced phase transition is attributed to the existence of intragranular stresses, induced by the decreased compensation of the ferroelastic energy during the formation of non- 180° domainwalls when decreasing the grain size and the large anisotropy of the thermal expansion. The results demonstrate the unique possibility of stabilizing ferroelectricity by reducing the grain size, which was not observed in other ferroic systems.

Titel der Zeitschrift, Zeitung oder Schriftenreihe: Acta Materialia
(Heft-)Nummer: 126
Verlag: Elsevier
Freie Schlagworte: Ferroics Phase transitions NMR Ferroelectrics Antiferroelectrics
Fachbereich(e)/-gebiet(e): 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft
11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Nichtmetallisch-Anorganische Werkstoffe
11 Fachbereich Material- und Geowissenschaften
Hinterlegungsdatum: 03 Jan 2017 07:13
ID-Nummer: doi:10.1016/j.actamat.2016.12.049
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