從參考文獻中，得知單晶的ZnCr2O4在12.5 K具有反鐵磁性質。且介電常數對溫度圖中，約在15 K~30 K出現波峰，波峰最大值隨著頻率的增加往高溫區位移。
另一方面，我們發現ZnV2O4跟ZnCr2O4有著許多類似的特質。首先，ZnV2O4與ZnCr2O4都是屬於尖晶石結構，也因此X-ray繞射圖的繞射峰位置一致。質量上，釩(Vanadium)與鉻(Chromium)的原子序只相差一，原子量大小也相近。磁性上，ZnV2O4跟ZnCr2O4一樣都是屬於反鐵磁性質。基於以上幾種原因我們認為觀察這兩種材料的中間過程是有趣且可行的。於是使用固態反應法(solid state reaction method)製作Zn(Cr1-xVx)2O4 ( X = 0, 0.2, 0.4, 0.6, 0.8, 1)這一系列的樣品。
經過反覆的嘗試，我們找到製作這一系列樣品的最佳方式。經過GSAS的擬合與計算後，驗證了樣品的品質是良好的。磁性方面，從X - T的量測中得知，ZnCr2O4的磁性相轉變溫度為12.5 K，其磁性來源為Cr3離子。而中間系列的樣品，在12.5 K與15.2 K之間出現磁化率最大值，隨著釩(Vanadium) 摻雜比例的增加，磁化率最大值往高溫區位移。在介電常數的量測中，ZnV2O4不具有鐵電相轉變，因此我們判定ZnV2O4不是多鐵材料。而ZnCr2O4雖然有反鐵磁相變，但是我們沒有觀察到鐵電相變。

In the references, the ZnCr2O4 single crystal has the anti-ferromagnetic transition at temperature 12.5 K. The result of dielectric constant to the temperature shows a peak between 15 K and 30 K. This peak will shift to high temperature with the increasing frequency.
On the other hand, we found that ZnV2O4 has some similar properties with ZnCr2O4. First, ZnCr2O4 and ZnV2O4 are both spinel structures. Therefore, they have the same XRD pattern. Second, Vanadium’s atomic number is near to Chromium and both of them have close atomic mass. Third, both of them are anti-ferromagnetic in their magnetic properties. All the reasons we mentioned excited our curiosity to the research in these materials by using solid state reaction method to provide the series of Zn(Cr1-xVx)2O4 ( X = 0, 0.2, 0.4, 0.6, 0.8, ) samples.
After the growth process, we used GSAS calculation to prove all the samples are in good quality. From the X – T measurement, we found that ZnCr2O4 has the magnetic phase transition at temperature 12.5 K and that indicated the source of magnetic comes from Cr3+ ions. Moreover, the samples which with medium Vanadium doping ratios have the maximum magnetic susceptibilities showed between 12.5 K and 15.2 K. With the increasing of Vanadium doping ratios, the maximum magnetic susceptibilities moved toward to higher temperature. From the measurement of dielectric constant, ZnV2O4 does not have ferroelectric transition; therefore we determined it is not multiferroics. For ZnCr2O4, although it has the anti-ferromagnetic transition, there did not show the ferroelectric transition.

目錄

致謝..........................................................................................................................iii
論文摘要...................................................................................................................v
Abstract...................................................................................................................vi
目錄.........................................................................................................................vii
圖目錄......................................................................................................................ix
第一章:簡介…………………………………………………………………..……1
1.1 多鐵性材料…………………………………………………………...…..1
1.2 幾何自旋頓挫態系統.................................................................................6
1.3 樣品介紹………………………………………………………………...10
1.3.1 ZnCr2O4系統…………………………………………………….10
1.3.2 ZnV2O4系統……………………………………………………..21
1.4 Zn(Cr1-xVx)2O4，X = 0, 0.2, 0.4, 0.6, 0.8, 1.0研究動機………………...23
第二章:實驗儀器與方法…………………………………………………………24
2.1 X-ray繞射儀……………………………………………………………..24
2.1.1 粉末繞射分析儀 D5000………………………………………….24
2.1.2 粉末繞射分析儀 D2 Phaser……………………………………...27
2.2 磁性量測儀器…………………………………………………………...29
2.2.1 超導量子干涉磁量儀……………………...……………………29
2.2.2 磁性量測方式………………………………...…………………37
2.3介電性量測儀器……………………………………….…………………39
2.3.1 Close Cycle Refrigerator System………………...………………39
2.3.2 平行板電容樣品製作……………………………...……………40
第三章:實驗結果與討論…………………………………………………………41
3.1 Zn(Cr1-xVx)2O4，X=0, 0.2, 0.4, 0.6, 0.8, 1.0樣品製備與X-ray結構檢測.41
3.1.1第一次樣品製備(ZnCr2O-4)……………………………..…………41
3.1.2第二次樣品製備(Zn(Cr1-xVx)2O4，X = 0, 0.2, 0.8, 1.0)……….….45
3.1.3第三次樣品製備與X-ray結構檢測…………..…………..………48
3.2磁性實驗結果與討論…………………………………………….………62
3.3介電性實驗結果與討論………………………………………….………79
第四章:結論………………………………………………………………………83
參考文獻………………………………………………………………….………85

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