TY - JOUR
T1 - Contrasting temperature dependences of isostructural one-dimensional ferroelectric crystals NH4HSO4and RbHSO4in terms of thermal conductivities
AU - Hoshino, Norihisa
AU - Akutagawa, Tomoyuki
N1 - Funding Information:
This work was financially supported by Grants-in-Aid for Scientific Research (C; Grant No. 20K05535) by the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT), CREST (Grant No. JPMJCR18I4) by the Japan Science and Technology Agency, and the “Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials” from MEXT.
Publisher Copyright:
© 2020 Author(s).
PY - 2020/11/21
Y1 - 2020/11/21
N2 - Temperature-dependent thermal conductivities are reported for one-dimensional (1D) hydrogen-bonding ferroelectric crystals of isostructural compounds NH4HSO4 and RbHSO4. As the temperature was decreased from 300 K, at which point they were paraelectric in the P21/n space group, their thermal conductivities decreased, similar to those of glassy materials. At the ferroelectric transition points (T1A = 270 K for NH4HSO4 and T1R = 264 K for RbHSO4), a change from P21/n to Pn space groups was observed, and the thermal conductivity of the NH4HSO4 crystal decreased without any anomalies, whereas that of RbHSO4 increased, similar to that of crystalline materials. At the second ferroelectric-to-paraelectric transition point of NH4HSO4 (T2A = 154 K), the thermal conductivity increased from 1.00 W m-1 K to 1.32 W m-1 K and increased with a subsequent decrease in temperature, similar to that of crystalline materials. Single-crystal x-ray structure analyses revealed that the thermal conductivity transition of RbHSO4 at T1R = 264 K corresponds to the rotational motion excitation of the HSO4- chains. The abrupt thermal conductivity jump of NH4HSO4 was likely related to the order-disorder type transition in NH4+ ions, accompanied by lattice vibration excitation, coupled with internal rotation. At the T2A ferroelectric-to-paraelectric phase transition of NH4HSO4, 21 crystal symmetry recovery was observed, similar to the Rochelle salt, and the space group at low temperatures was P21/n. For the RbHSO4 crystals, the thermal conductivity parallel to the 1D chains was 1.5-times higher than the corresponding perpendicular orientation.
AB - Temperature-dependent thermal conductivities are reported for one-dimensional (1D) hydrogen-bonding ferroelectric crystals of isostructural compounds NH4HSO4 and RbHSO4. As the temperature was decreased from 300 K, at which point they were paraelectric in the P21/n space group, their thermal conductivities decreased, similar to those of glassy materials. At the ferroelectric transition points (T1A = 270 K for NH4HSO4 and T1R = 264 K for RbHSO4), a change from P21/n to Pn space groups was observed, and the thermal conductivity of the NH4HSO4 crystal decreased without any anomalies, whereas that of RbHSO4 increased, similar to that of crystalline materials. At the second ferroelectric-to-paraelectric transition point of NH4HSO4 (T2A = 154 K), the thermal conductivity increased from 1.00 W m-1 K to 1.32 W m-1 K and increased with a subsequent decrease in temperature, similar to that of crystalline materials. Single-crystal x-ray structure analyses revealed that the thermal conductivity transition of RbHSO4 at T1R = 264 K corresponds to the rotational motion excitation of the HSO4- chains. The abrupt thermal conductivity jump of NH4HSO4 was likely related to the order-disorder type transition in NH4+ ions, accompanied by lattice vibration excitation, coupled with internal rotation. At the T2A ferroelectric-to-paraelectric phase transition of NH4HSO4, 21 crystal symmetry recovery was observed, similar to the Rochelle salt, and the space group at low temperatures was P21/n. For the RbHSO4 crystals, the thermal conductivity parallel to the 1D chains was 1.5-times higher than the corresponding perpendicular orientation.
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U2 - 10.1063/5.0028153
DO - 10.1063/5.0028153
M3 - Article
C2 - 33218251
AN - SCOPUS:85096569860
VL - 153
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 19
M1 - 194503
ER -