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首页> 外文学位 >TEMPERATURE AND PRESSURE DEPENDENCES OF ELASTIC CONSTANTS IN MERCURY-TELLURIDE CONTAINING 3 AND 20 PERCENT MANGANESE FROM ULTRASONIC-VELOCITY MEASUREMENTS
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TEMPERATURE AND PRESSURE DEPENDENCES OF ELASTIC CONSTANTS IN MERCURY-TELLURIDE CONTAINING 3 AND 20 PERCENT MANGANESE FROM ULTRASONIC-VELOCITY MEASUREMENTS

机译：超声波测速法测定含3％和20％锰的碲化汞中弹性常数的温度和压力依赖性

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摘要

Measurements have been made of the transit times of 30 MHZ longitudinal and transverse ultrasonic waves in Hg(,0.97)Mn(,0.03)Te and Hg(,0.8)Mn(,0.2)Te as functions of the temperature from 1.5 to 298 K and of hydrostatic pressure P up to 2.5 kbar. Second order elastic constants obtained therefrom are C(,L) = (C(,11) + C(,12) + 2C(,44)) / 2, C(,S) = (C(,11) - C(,12)) / 2 and C(,44). While the temperature dependences of the elastic constants of HgTe and Hg(,0.97)Mn(,0.03)Te are very similar, those of Hg(,0.8)Mn(,0.2)Te are significantly smaller. The temperature dependences of elastic constants can be fitted by Lakkad's anharmonic model. Below 200 K the explicitly temperature dependent term is more important than the thermal expansion term. From the elastic constants at 1.5 K the elastic Debye temperatures are deduced to be 143.2 (+OR-) 0.4 K for Hg(,0.97)Mn(,0.03)Te and 144.1 (+OR-) 0.9 K for Hg(,0.8)Mn(,0.2)Te respectively.;In Hg(,1-x)Mn(,x)Te samples the values of (PAR-DIFF)C(,L)/(PAR-DIFF)P are about equal, the values of (PAR-DIFF)C(,S)/(PAR-DIFF)P and (PAR-DIFF)C(,44)/(PAR-DIFF)P decrease with increasing x except that (PAR-DIFF)C(,S)/(PAR-DIFF)P is equal in HgTe and Hg(,0.97)Mn(,0.03)Te. The second order elastic constants at 298 K are used to deduce the harmonic force constants and Phillips ionicity for the Hg(,1-x)Mn(,x)Te samples with x > 0. The presence of 3d electrons on Mn makes the bond-bending force constants smaller in Hg(,1-x)Mn(,x)Te for larger x. From application of Bienenstock and Burley's model of structure and bonding, it is found that for a number of III-V and II-VI compounds, (gamma)(,C(,11)) is independent of ionicity, but (gamma)(,C(,S)) (except for HgTe and Hg(,0.97)Mn(,0.03)Te) and (gamma)(,C(,44)) (except for GaP, GaAs and GaSb) increase with decreasing ionicity. Use of modified Born criterion of Demarest et al., and the elastic constants data up to 2.5 kbar structural transition pressures P(,t) are deduced to be 12.6 and 10 kbar for Hg(,0.97)Mn(,0.03)Te and Hg(,0.8)Mn(,0.2)Te, respectively, at room temperature. The Phillips' relation for correlating ionicity with the change in Gibbs free energy at P(,t) is satisfied by Hg(,1-x)Mn(,x)Te samples which have lower P(,t) and higher ionicity for larger x. For the Hg(,1-x)Mn(,x)Te samples, present models are adequate for obtaining three of the third order elastic constants and one of the anharmonic force constants but not for determining the remaining three of the third order and two of the anharmonic force constants from the pressure dependences data of elastic constants.
机译：测量了Hg（，0.97）Mn（，0.03）Te和Hg（，0.8）Mn（，0.2）Te中30 MHZ纵向和横向超声波在1.5至298 K温度之间的传播时间静水压力P高达2.5 kbar。从中获得的二阶弹性常数为C（，L）=（C（，11）+ C（，12）+ 2C（，44））/ 2，C（，S）=（C（，11）-C（ ，12））/ 2和C（，44）。虽然HgTe和Hg（，0.97）Mn（，0.03）Te的弹性常数与温度的关系非常相似，但Hg（，0.8）Mn（，0.2）Te的弹性常数却小得多。弹性常数的温度依赖性可以通过Lakkad的非谐模型拟合。低于200 K时，与温度明显相关的项比热膨胀项更重要。从1.5 K的弹性常数推算得出Hg（，0.97）Mn（，0.03）Te的弹性德拜温度为143.2（+ OR-）0.4 K，Hg（，0.8）的144.1（+ OR-）0.9 K分别为Mn（，0.2）Te .;在Hg（，1-x）Mn（，x）Te样品中，（PAR-DIFF）C（，L）/（PAR-DIFF）P的值大约相等， （PAR-DIFF）C（，S）/（PAR-DIFF）P和（PAR-DIFF）C（，44）/（PAR-DIFF）P的值随x的增加而减小，除了（PAR-DIFF）C（， S）/（PAR-DIFF）P在HgTe和Hg（，0.97）Mn（，0.03）Te中相等。使用298 K的二阶弹性常数来推导x> 0的Hg（，1-x）Mn（，x）Te样品的谐波力常数和菲利普斯离子性。Mn上3d电子的存在使键合对于较大的x，弯曲力常数在Hg（，1-x）Mn（，x）Te中较小。从Bienenstock和Burley的结构和键合模型的应用中发现，对于许多III-V和II-VI化合物，（γ）（，C（，11））与离子性无关，但（γ）（ ，C（，S））（HgTe和Hg（，0.97）Mn（，0.03）Te除外）和γ（，C（，44））（GaP，GaAs和GaSb除外）随着离子度的降低而增加。使用Demarest等人的修正的Born准则，对于Hg（，0.97）Mn（，0.03）Te和Hg，推导出高达2.5 kbar结构转变压力P（，t）的弹性常数数据分别为12.6和10 kbar （，0.8）Mn（，0.2）Te分别在室温下。 Hg（，1-x）Mn（，x）Te样品满足P（，t）较低的P（，t）和更高的离子性的离子与P（，t）吉布斯自由能变化相关的菲利普斯关系X。对于Hg（，1-x）Mn（，x）Te样品，本模型足以获取三个三阶弹性常数和一个非谐力常数，但不能确定其余三个三阶弹性常数和两个非弹性力常数从弹性常数的压力依赖性数据中得出。

著录项

  • 作者

    CHAO, MARIA HUEY-MING.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Condensed matter physics.
  • 学位 Ph.D.
  • 年度 1983
  • 页码 93 p.
  • 总页数 93
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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