摻雜鍶對釹-鈣-錳氧化物的磁耦合增強效應; Enhancement of Magnetic coupling in Nd0.5Ca1-xSrxMnO3 by dopping Sr

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题名:	摻雜鍶對釹-鈣-錳氧化物的磁耦合增強效應;Enhancement of Magnetic coupling in Nd0.5Ca1-xSrxMnO3 by dopping Sr
作者:	薛雍霖;Yung-Lin Shiun
贡献者:	物理研究所
关键词:	磁耦合增強效應;龐磁阻材料;物理特性量測系統;交流磁化率;楊-泰勒扭曲;Jahn-Taylor distortion;ferromagnetic;PPMS;Nd0.5Sr0.5MnO3;GSAS;x-ray diffraction;Nd0.5Ca0.5−ySryMnO3
日期:	2007-06-20
上传时间:	2009-09-22 10:59:05 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	樣品Nd0.5Ca0.5-ySryMnO3的製作方法，乃是採用標準的固態反應法。Nd0.5Ca0.5-ySryMnO3 的晶體結構已透過中子與X 光繞射實驗分析。在室溫下0≦y<0.5的樣品屬於斜方晶系的Pbnm 空間群，Nd0.5Sr0.5MnO3為Imma晶體對稱。並且藉著變溫X光實驗發現Nd0.5Ca0.5MnO3、Nd0.5Ca0.19Sr0.31MnO3、Nd0.5Sr0.5MnO3的樣品在溫度為260K、160K、180K有楊-泰勒扭曲。並使用物理特性量測系統(Physical property measurement system)量測其磁磁化率。由結果得知Sr的摻雜使得Mn+4-O- Mn+3的夾角變大，使其耦合增強造成鐵磁的相轉換溫度往高溫移動。從磁化率的結果可以明顯的發現Nd0.5Ca0.19Sr0.31MnO3、Nd0.5Sr0.5MnO3在高溫250Kk左右有兩個峰值，可能是由於Mn+4及Mn+3所造成的鐵磁有序行為。本研究得以獲得磁場對溫度的相圖，呈現Nd0.5Ca0.5-ySryMnO3 系統的物理特性。 Polycrystalline samples of Nd0.5Ca0.5−ySryMnO3 with 0≦y≦0.5 are prepared by the standard solid state reaction technique. Crystall structure of Nd0.5Ca0.5-ySryMnO3 at room temperature is revealed by using x-ray diffraction technologies. It crystallized into an orthorombic Pbnm phase at room temperature. Nd0.5Sr0.5MnO3 crystallized into an orthorombic Imma phase. We discover that Nd0.5Ca0.5MnO3、Nd0.5Ca0.19Sr0.31MnO3、Nd0.5Sr0.5MnO3 have the Jahn-Taylor distortion in X-ray diffraction patterns at the temperatures : 260K、160K、180K. The magnetization measurements were carried out with the a Physical Property Measurement System . By the result know doping Sr causes the angle of Mn+4-O- Mn+3 to become larger. Causes its coupling enhancement change the temperature of ferromagnetic transforms toward the higher temperature. We discover that Nd0.5Ca0.19Sr0.31MnO3、Nd0.5Sr0.5MnO3 have two peak at 250 K, due to the ferromagnetic ordering of Mn+3 and Mn+4. This research can obtain the magnetic field to the temperature phase diagram, presents the Nd0.5Ca0.5-ySryMnO3 system the physical property.
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