多鐵材料鐿錳氧化物奈米棒之磁聲交互作用與尺寸效應研究

Spin–phonon interaction and Size effect on multiferroics YbMn2O5 nanorods

施瑋哲(Wei-Jhe Shih)

指導教授 ： 楊仲準

中原大學/理學院/應用物理研究所/碩士(2014年)

https://doi.org/10.6840/cycu201400550

摘要

利用水熱合成法製成多鐵材料YbMn2O5 奈米棒，再依不同熱退
火溫度鍛燒得到各尺寸樣品。以X 光粉末繞射儀鑑定樣品均為斜方
晶pbam 純相。透過穿透式電子顯微鏡影像分析統計得知樣品尺寸，
以短軸×長軸的標示為26(8) nm×50(23) nm、28(8) nm×49(20)、28(8)
nm×50(19) nm、29(8) nm ×48(19) nm、60(18) nm×98(34)、59(15)
nm ×96(32) nm。以選區電子繞射分析發現，樣品長軸均為晶軸c 軸
方向，故以奈米棒長軸長度來標示不同樣品。
量測各樣品磁化率得知， = 98、96 nm 樣品在38~40K 內部
磁性產生排列，其他樣品則無。而在2K 溫度環境量測磁滯曲線，也
是僅有大尺寸樣品的矯頑力較明顯，其中 = 96 nm 樣品的矯頑力
最大。由上述兩點表示尺寸效應與磁性相關。
變溫拉曼光譜實驗說明，在外加磁場為0T 時 = 50、98、與
96 nm樣品測得之拉曼光譜，分別在T = 130 ~ 170K、T = 100 ~ 240K、
與T = 80 ~ 130K 產生拉曼位移位置的扭曲變化。在外加磁場為0.2T
時，三個樣品的峰值皆無明顯隨著溫度改變而扭曲，這表示外加磁場
對拉曼振盪模產生影響，也意味著磁聲交互作用的存在。
將拉曼光譜與變溫XRD 量測的結構變化比較，可發先磁聲交互
作用只發生在bc 平面上。

關鍵字

磁聲效應

並列摘要

Various size of YbMn2O5 nanorods were fabricated by combining
hydrothermal, ane with diffierent annealing temperatures. X-ray diffraction
experiments reveal that all the samples are crystallized in orthorhombic with space
group Pbam phase. Six samples with annealing temperatures of 240、500、700、800、
900、1000 °C are idendified by TEM and SAED scheme, which can be labeled in the
form of long axis × short axis as 26(8) nm×50(23) nm、28(8) nm×49(20)、28(8) nm×
50(19) nm、29(8) nm ×48(19) nm、60(18) nm×98(34)、59(15) nm ×96(32) nm,
respectively。All the long axis of nanorods are parallel to c axis of the crystal. The
symbol is employed to label the long axis of nanorods and in place of sample
name.
Susceptibility measurements for each sample ,only simple = 98、96 nm at
38 ~ 40K samples have antiferromagnetic (AFM) peak. The temperatures measured at
2K hysteresis curve, coercivity is also the only large sample size is relatively obvious,
and the coercivity of = 96 nm sample is maximum. Represented by the two size
effects associated with magnetic.
Variable temperature Raman spectroscopy experiments show that when the
magnetic field is 0T = 50、98、and 96 nm Raman spectra of the sample
measured, respectively, at T = 130 ~ 170K, T = 100 ~ 240K, and T = 80 ~ 130K
distorting Raman shift change position. When the magnetic field is 0.2T, the peak of
the three samples were not significantly distorted as the temperature changes. It
indicating that the spin-phonon interactions exist.
By comparing the structure of VT-XRD and VT-Raman spectroscopy
experiments, we found the effect of spin-phonon interactions is appears on the bc
plane.

並列關鍵字

Spin–phonon interaction

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