PHONON-DISPERSION BRANCHES IN ALPHA-QUARTZ
PHONON-DISPERSION BRANCHES IN ALPHA-QUARTZ
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DOI：
10.1088/0022-3719/13/36/014
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发表时间：
1980-01-01
期刊：
影响因子：
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通讯作者：
RZANY, H
中科院分区：
文献类型：
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作者：
DORNER, B;GRIMM, H;RZANY, H
作者在室温下测量了α石英中（xi 0 0）和（xi xi 0）方向的六个最低声子色散分支。与巴伦等人的晶格动力学计算定性一致。1976年，好。在数量上的差异中，最引人注目的出现在（xi xi 0）方向的声学模式中。对称（“纵向”）分支具有较低的初始斜率（4.70 km s-1），然后是反对称（“横向”）分支（5.4 km s-1）。这种不寻常的行为，它出现在相对较小的声子波长可观察到的非弹性中子散射是相反的，从弹性常数计算出的长波长的声速给出5.724公里s-1的对称和5.114公里s-1的上反对称分支。他们用第一声区和零声区的不同声速解释了这一现象。
The authors measured the six lowest phonon dispersion branches in alpha quartz at room temperature for the (xi 00) and (xi xi 0) directions. The qualitative agreement with lattice dynamical calculations by Barron et al.(1976) is good. Among the quantitative differences the most striking appears in the acoustic modes in the (xi xi 0) direction. The symmetric ('longitudinal') branch has a lower initial slope (4.70 km s-1) and then one antisymmetric ('transverse') branch (5.4 km s-1). This unusual behaviour, which appears at relatively small phonon wavelengths observable by inelastic neutron scattering is in contrast to the long-wavelength sound velocities calculated from elastic constants which give 5.724 km s-1 for the symmetric and 5.114 km s-1 for the upper antisymmetric branch. They explain this observation by the different sound velocities in the first and zero sound regimes.