### 抄録

The orientational ordering in a system of dipolar molecules located on a trigonal lattice is studied in the eight-sublattices approximation. Our concrete example is SO_{2} molecules in β-hydroquinone clathrate. It is assumed that the molecules interact with each other via effective dipole-dipole interactions, and that the crystal field acting on those molecules is of the form W_{A} = C_{COS}[ν(φ-δ_{A})], where φ is a rotational angle and A is a sublattice number. If ν is an odd integer, we assume that δ_{A} may different for different A. The mean electric field which depends on the depolarization field is obtained. Various cases of C, ν, δ_{A} are investigated. Results are as follows: the possible dipole arrangement is antiferroelectric in all cases; the phase transition for ν = 2, 4, 5, 6 is of second order; if ν = 1, no disordered phase occurs; if ν = 3, the phase transition is weakly of first order excep for special cases; the C dependence of the transition temperature is weak unless ν = 2; δ_{A} chiefly determines the equilibrium direction. A comparison with experiment suggests that the low-temperature phase of SO_{2}-β-hydroquinone has ν = 2 or 3, and that interactions between enclosed SO_{2} molecules other than dipole-dipole interactions may be also effective.

元の言語 | 英語 |
---|---|

ページ（範囲） | 1364-1370 |

ページ数 | 7 |

ジャーナル | journal of the physical society of japan |

巻 | 66 |

発行部数 | 5 |

DOI | |

出版物ステータス | 出版済み - 1 1 1997 |

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### All Science Journal Classification (ASJC) codes

- Physics and Astronomy(all)

### これを引用

**Effects of a Crystal Field on the Orientational Phase Transition in a System of Dipoles : A Mean-Field Study of SO _{2}-β-Hydroquinone Clathrate.** / Imasaka, Tomoko; Hirokawa, Shoji.

研究成果: ジャーナルへの寄稿 › 記事

}

TY - JOUR

T1 - Effects of a Crystal Field on the Orientational Phase Transition in a System of Dipoles

T2 - A Mean-Field Study of SO2-β-Hydroquinone Clathrate

AU - Imasaka, Tomoko

AU - Hirokawa, Shoji

PY - 1997/1/1

Y1 - 1997/1/1

N2 - The orientational ordering in a system of dipolar molecules located on a trigonal lattice is studied in the eight-sublattices approximation. Our concrete example is SO2 molecules in β-hydroquinone clathrate. It is assumed that the molecules interact with each other via effective dipole-dipole interactions, and that the crystal field acting on those molecules is of the form WA = CCOS[ν(φ-δA)], where φ is a rotational angle and A is a sublattice number. If ν is an odd integer, we assume that δA may different for different A. The mean electric field which depends on the depolarization field is obtained. Various cases of C, ν, δA are investigated. Results are as follows: the possible dipole arrangement is antiferroelectric in all cases; the phase transition for ν = 2, 4, 5, 6 is of second order; if ν = 1, no disordered phase occurs; if ν = 3, the phase transition is weakly of first order excep for special cases; the C dependence of the transition temperature is weak unless ν = 2; δA chiefly determines the equilibrium direction. A comparison with experiment suggests that the low-temperature phase of SO2-β-hydroquinone has ν = 2 or 3, and that interactions between enclosed SO2 molecules other than dipole-dipole interactions may be also effective.

AB - The orientational ordering in a system of dipolar molecules located on a trigonal lattice is studied in the eight-sublattices approximation. Our concrete example is SO2 molecules in β-hydroquinone clathrate. It is assumed that the molecules interact with each other via effective dipole-dipole interactions, and that the crystal field acting on those molecules is of the form WA = CCOS[ν(φ-δA)], where φ is a rotational angle and A is a sublattice number. If ν is an odd integer, we assume that δA may different for different A. The mean electric field which depends on the depolarization field is obtained. Various cases of C, ν, δA are investigated. Results are as follows: the possible dipole arrangement is antiferroelectric in all cases; the phase transition for ν = 2, 4, 5, 6 is of second order; if ν = 1, no disordered phase occurs; if ν = 3, the phase transition is weakly of first order excep for special cases; the C dependence of the transition temperature is weak unless ν = 2; δA chiefly determines the equilibrium direction. A comparison with experiment suggests that the low-temperature phase of SO2-β-hydroquinone has ν = 2 or 3, and that interactions between enclosed SO2 molecules other than dipole-dipole interactions may be also effective.

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U2 - 10.1143/JPSJ.66.1364

DO - 10.1143/JPSJ.66.1364

M3 - Article

VL - 66

SP - 1364

EP - 1370

JO - Journal of the Physical Society of Japan

JF - Journal of the Physical Society of Japan

SN - 0031-9015

IS - 5

ER -