| 非晶态低温反常热导率的量子理论 | |
| 赵维良 | |
| Subtype | 硕士 |
| Thesis Advisor | 周本濂 |
| 1991 | |
| Degree Grantor | 中国科学院金属研究所 |
| Place of Conferral | 中国科学院金属研究所 |
| Abstract | 本文依据七十年代初发展起来的两能级隧道态的理论模型，考虑隧道态与声子场的相互作用。从声子在无序固体中的输运性质入手，研究声子输运的波耳兹量方程。在研究声子输运过程中合理略去声子与声子之间的相互作用，声子与边界作用等散射过程。对在晶绝缘固体，在极低温下，认为声子与隧道态的作用将是阻碍热流使非晶绝缘固体成为有限热导率的主要作用。具体计算声子与隧道态相互作用的量子力学跃迁矩阵元，假定在非晶绝缘体中，隧道态的粒子分布为玻耳兹曼分布，考虑各向同性介质的简单情况，计算非晶绝缘固体的热导率，得出极低温下热导率的T~2关系。已有理论处理这一问题时所采用的是驰豫时间近似，而计算驰豫时间时采用了爱因斯坦处理原子与辐射场相互作用时所采用的半经典方法。本文完全从量子理论和玻耳兹主程出发来考虑这一问题，物理图象更为基本和清晰。 |
| Other Abstract | Discussion is begun with phonon's transporting character and Boltzman equation and based on "tunnelling level" theory developed in 70's. A system in which phonon state couples with two level system is considered. The interaction of phonons and that between phonon and boundary are neglected. Under extremely low temperature, for the amorsphous state solid, the interaction between phonon and tunnelling state is regarded as the main part to hinter the heat current and to make the heat conductivity of an amorphous state solid be a limitting value. The transition matrix element of interaction between phonon state and tunnelling state is calculated. Assuming that the particle in the tunnelling state obeys Boltzman Distribution and the medium is isotropic, for the heat conductivity of an amorphous solid, the T~2 relation is obtain. In the pioneer's work, relaxation time approximation was used to solve such a problem and the relaxation time was calculated with a quasi-classical method like that Enstein used to discuss the interaction between atom and radiation field. It should be noted that, in this thesis, our calculation is based on the quantum theory and the relaxation time approximation is not used. We only use Boltzman equation and quantum transition theory to consider this problem, and the physical image is more basic and distinct. |
| Pages | 32 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.imr.ac.cn/handle/321006/17521 |
| Collection | 中国科学院金属研究所 |
| Recommended Citation GB/T 7714 | 赵维良. 非晶态低温反常热导率的量子理论[D]. 中国科学院金属研究所. 中国科学院金属研究所,1991. |
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