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홍정택,이병완,고재현,Irena Jankowska-Sumara,Maria Podgórna,Andrzej Majchrowski 한국물리학회 2018 Current Applied Physics Vol.18 No.6
The phase transition sequence of a PbHf0.7Sn0.3O3 single crystal was investigated by using Brillouin spectroscopy. The longitudinal acoustic mode showed three distinct changes at ∼370 K, ∼455 K and ∼495 K which corresponded to the antiferroelectric 1 → antiferroelectric 2 → intermediate → paraelectric phase transitions upon heating. The paraelectric phase was characterized by softening acoustic mode, increasing acoustic damping and the appearance of quasielastic central peaks which were observed upon approaching the phase transition temperature. The relaxation times derived from the acoustic mode anomalies and the central peak were consistent with each other and showed a slowing-down behavior. These precursor phenomena were attributed to the polar clusters having broken inversion symmetry. The substitution of Hf with Sn induced a very soft intermediate phase between the paraelectric and the antiferroelectric phases, where the longitudinal acoustic mode exhibited the lowest mode frequency along with substantially high acoustic damping. The transverse acoustic mode, which was observed in the two antiferroelectric phases, did not appear in the intermediate phase. These results indicated that the average symmetry of the intermediate phase may be cubic consisting of fine ferroelastic domains.
Hong, Jung-Taek,Lee, Byoung Wan,Ko, Jae-Hyeon,Jankowska-Sumara, Irena,Podgó,rna, Maria,Majchrowski, Andrzej ELSEVIER 2018 Current Applied Physics Vol.18 No.6
<P><B>Abstract</B></P> <P>The phase transition sequence of a PbHf<SUB>0.7</SUB>Sn<SUB>0.3</SUB>O<SUB>3</SUB> single crystal was investigated by using Brillouin spectroscopy. The longitudinal acoustic mode showed three distinct changes at ∼370 K, ∼455 K and ∼495 K which corresponded to the antiferroelectric 1 → antiferroelectric 2 → intermediate → paraelectric phase transitions upon heating. The paraelectric phase was characterized by softening acoustic mode, increasing acoustic damping and the appearance of quasielastic central peaks which were observed upon approaching the phase transition temperature. The relaxation times derived from the acoustic mode anomalies and the central peak were consistent with each other and showed a slowing-down behavior. These precursor phenomena were attributed to the polar clusters having broken inversion symmetry. The substitution of Hf with Sn induced a very soft intermediate phase between the paraelectric and the antiferroelectric phases, where the longitudinal acoustic mode exhibited the lowest mode frequency along with substantially high acoustic damping. The transverse acoustic mode, which was observed in the two antiferroelectric phases, did not appear in the intermediate phase. These results indicated that the average symmetry of the intermediate phase may be cubic consisting of fine ferroelastic domains.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We measure the elastic properties of PbHf<SUB>0.7</SUB>Sn<SUB>0.3</SUB>O<SUB>3</SUB> single crystals. </LI> <LI> The acoustic anomalies related the phase transition are determined. </LI> <LI> The effect of Sn substitution on the elastic property is determined. </LI> </UL> </P>