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題名 | RbTiOAsO[feb2]單晶的聲聲子研究=Study of Acoustic Phonons in RbTiOAsO[feb2]Single Crystal |
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作者 | 薛仲貴; 杜繼舜; Xue, Z. G.; Tu, C. S.; |
期刊 | Fu Jen Studies. Science and Engineering |
出版日期 | 19971200 |
卷期 | 31 1997.12[民86.12] |
頁次 | 頁67-75 |
分類號 | 336.9 |
語文 | chi |
關鍵詞 | 布里元光學散射; 聲聲子; 鐵電相變; 第拜非同調近似式; Brillouin scattering; Acoustic phonon; Ferroelectric transition; Debye anharmonic approximation; |
中文摘要 | 本報告,是利用布里元光學散射實驗,進行研究RbTi0AsO□(RTA)單晶的LA﹝001﹞聲聲子光譜與其溫度的關係。發現當溫度升高時,RTA的聲聲子頻率顯示出明顯的減弱,直到其鐵電相變溫度(T□∼800℃)以上時才趨於定值,這個現象被歸因於聲聲子的"軟模(soft-mode)"出現。其聲子半寬頻率則是在溫度接近相變溫度時,有明顯的最大值,我們認為order-parameter(polarization)的fluctuations是這個行為的主因。藉著使用第拜非同調近似式(Debye anharmonic approximation),非耦合的聲子頻率□(0)= 44.28GH□,第拜溫度θ=300K及非同調係數A=6x10□K□也被得到。 |
英文摘要 | The longitudinal (LA) (001) Brillouin back-scattering phonon spectra have been measured as a function of temperature (25-871 ℃) for RbTiOAsO, (RTA) single crystal. As temperature increase, the acoustic phonon frequency shows a strong softening (negative coupling) and reaches its a minimum value above the ferroelectric (FE) transition temperature T□~800℃. Correspondingly, the half-width of phonon exhibits a broad maximum (near T□) that was attributed to the order-parameter fluctuations. The Debye bare phonon frequency □(0) Debye temperature θ, and anhamonicity were also obtained by using the Debye anharmonic approximation. |
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