奈米級尺寸顆粒 Bi1-xDyxFeO3 多鐵材料之光譜性質研究
dc.contributor | 劉祥麟 | zh_TW |
dc.contributor | Hsiang-Lin Liu | en_US |
dc.contributor.author | 蘇郁茜 | zh_TW |
dc.contributor.author | Yu-Chien, Su | en_US |
dc.date.accessioned | 2019-09-05T02:26:01Z | |
dc.date.available | 2012-8-30 | |
dc.date.available | 2019-09-05T02:26:01Z | |
dc.date.issued | 2011 | |
dc.description.abstract | 本論文研究奈米級尺寸顆粒 Bi1-xDyxFeO3(x = 0.00、0.05、0.10、0.15、0.20、0.30、0.40)多鐵材料的全頻反射與拉曼散射光譜。隨著摻雜鏑離子濃度的增加,紅外光與拉曼活性振動模的變化符合x 光繞射能譜的晶格結構分析:(i)0.00 ≤ x ≤ 0.05 屬於空間群 R3c 菱形晶系結構;(ii)0.20 ≤ x ≤ 0.40屬於空間群 Pnma 正交晶系結構;(iii)x = 0.10與 0.15 顯示兩相共存狀態。此外,高頻紅外光吸收與拉曼散射光譜展現多倍磁振子的貢獻,代表鏑離子的摻雜和奈米級尺寸顆粒導致Bi1-xDyxFeO3本身磁性結構的改變。更有趣地是低頻拉曼散射光譜顯現擴散響應,我們認為鏑離子的摻雜引起晶格局部扭曲,降低電荷的漂移率,造成Bi1-xDyxFeO3的電性傳導屬於電荷躍遷機制。 高溫拉曼散射光譜顯示:(i)在預期的尼爾溫度附近,各拉曼峰的參數(頻率位置、半高寬、及強度)並未發生明顯地異常變化,這代表自旋與聲子的交互作用微弱;(ii)擴散響應之半高寬隨溫度升高而變小,Bi1-xDyxFeO3電荷彼此之間的碰撞率降低,暗指其電性傳導愈佳化。 | zh_TW |
dc.description.abstract | We present the results of infrared, optical reflectivity and Raman-scattering measurements of nano-sized Bi1-xDy xFeO3 (x = 0, 0.05, 0.10, 0.20, 0.30, and 0.40) polycrystalline samples. It is found that when doping with Dy on Bi-site, the variations of infrared and Raman-active phonon modes are consistent with the analysis of x-ray powder diffraction spectra: (i) rhombohedral space group R3c as 0.00 ≤ x ≤ 0.05;(ii) dominant orthorhombic group Pnma as 0.20 ≤ x ≤ 0.40; and (iii) rhombohedral and orthorhombic mixings as x = 0.10 and 0.15. Moreover, multimagnon excitations are observed in both infrared absorption and high-frequency Raman-scattering spectra, indicating Dy doping and the nano-sized grains modify the magnetic structures of these materials. Interestingly, low-frequency Raman-scattering spectra exhibit diffusive response, reflecting the substitution of Dy for Bi induces the local lattice distortion and a concomitant reduction in the carrier mobility which manifest in the carrier hopping mechanism in Bi1-xDy xFeO3. With increasing temperature, there are two important features to the Raman-scattering spectra: (i) no detectable phonon anomalies are observed near the Néel temperature, suggesting the spin-phonon coupling is weak; and (ii) the scattering rate of diffusive hopping of the carriers is decreasing, indicating the enhancement of conductivity in these materials. | en_US |
dc.description.sponsorship | 物理學系 | zh_TW |
dc.identifier | GN0698410415 | |
dc.identifier.uri | http://etds.lib.ntnu.edu.tw/cgi-bin/gs32/gsweb.cgi?o=dstdcdr&s=id=%22GN0698410415%22.&%22.id.& | |
dc.identifier.uri | http://rportal.lib.ntnu.edu.tw:80/handle/20.500.12235/102770 | |
dc.language | 中文 | |
dc.subject | 鉍鐵氧 | zh_TW |
dc.subject | 奈米顆粒 | zh_TW |
dc.subject | 多鐵 | zh_TW |
dc.subject | 光譜研究 | zh_TW |
dc.subject | BiFeO3 | en_US |
dc.subject | nano-sized grains | en_US |
dc.subject | multiferroic | en_US |
dc.subject | optical studies | en_US |
dc.title | 奈米級尺寸顆粒 Bi1-xDyxFeO3 多鐵材料之光譜性質研究 | zh_TW |
dc.title | Optical studies of nano-sized multiferroic Bi1-xDyxFeO3 grains | en_US |
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