Impurity Effect on a Structural Phase Transition Intermediate between the Order-Disorder and Displacive Types.

杂质对有序无序型和位移型中间结构相变的影响。

• 批准号: 09640689
• 负责人: SAITO Kazuya
• 金额: $ 2.11万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640689/
• 关键词: structural phase transition; Impurity Effect; polyphenyl; ac calorinetry; 熱容量; シミュレーション

1. In order to clarify the impurity effect on structural phase transition ranging from displacive type to order-disorder type thermodynamically, heat capacity calorimetry of high precision was planned. The experiments on the displacive and order-disorder systems had been completed before this project started. Since the sample remained was commercially unavailable, the ac calorimetry applicable to very small samples was chosen as the experimental technic. The chopped-light ac calorimeter with high thermal stability was developed.2. By quenching liquid solution of 4,4"-difluoro-p-terphenyl (DFTP) and 3,6-diphenyl-1,2,4,5-tetrazine (DPTZ), thin uniform sample of the solid solution was prepared and used for the ac calorimetry. Strong suppression of thermal anomaly of DFTP upon increasing DPTZ contents showed an intermediate phase transition was much more sensitive to the impurity than order-disorder transition in p-terphenyl and similarity to the displacive transition in biphenyl. It is highly desired to establish a unified understanding the impurity effect on structural phase transitions theoretically.3. Molecular dynamics simulations were made on a simple model showing a displacive phase transition. A discussion concerning the mechanism of the strong impurity effect in displacive systems was confirmed in part. That is, the strong effect has a close connection to localization of lattice vibration, I.e., the soft-mode.

1。为了阐明从位移类型到热力学的订单类型的结构相过渡的杂质效应，计划了高精度的热容量量热法。在该项目开始之前，已经完成了流离失所和订单系统系统的实验。由于样品在商业上不可用，因此选择适用于非常小样品的AC量热法作为实验技术。开发了具有较高热稳定性的切碎的光量热仪2。通过将4,4“ -Difluoro-P-甲苯基（DFTP）和3,6-二苯基-1,2,4,5-四嗪（DPTZ）淬灭液体溶液，制备了固体溶液的薄均匀样品，并用于AC量热应强烈地抑制DPTP的强烈抑制。 p-二苯基的阶段和与统一的相似性，在理论上，高度希望理解对结构相位的杂质效应。晶格振动的定位，即软模式。

项目成果

K.Saito: ""Distortion of Local Order Parameter Caused by Impurities in Displacive Phase Transition"" J.Phys.Soc.Jpn.67(9). 3137-3140 (1998)

K.Saito：“位移相变中杂质引起的局域有序参数畸变”J.Phys.Soc.Jpn.67(9)。

K.Saito et al.: "General Purpose Cryostat Applicable to Chopped-Light ac Calorinetry with Highly Stable Thermal Condition" 熱測定. 25(5). 150-153 (1998)

K. Saito 等人：“适用于具有高度稳定热条件的短切光交流量热法的通用低温恒温器”热测量 25(5)。

Y. Yamamura: "Disapperance of a Displacive Phase Transition in Crystalline Biphenyl by a, Small Amount of Impurity" J. Phys. Soc. Jpn.67・5. 1649-1654 (1998)

Y. Yamamura：“少量杂质导致结晶联苯中的位移相变消失”J. Phys. Jpn.67・5 (1998)。

K.Saito: "Distortion of Local Order Parameter Caused by Impurities in Displacive Phase Transition" J.Phys.Soc.Jpn.67(9). 3137-3140 (1998)

K.Saito：“位移相变中杂质引起的局域有序参数畸变”J.Phys.Soc.Jpn.67(9)。

Y.Yamamura, K.Saito, I.Ikemoto & M.Sorai: ""Entropic Evidence of the Order-Disorder Nature of the Phase Transition in rho-Terphenyl Crystal"" J.Phys. : Condensed Matt.10(15). 3359-3366 (1998)

Y.Yamamura、K.Saito、I.Ikemoto