劉祥麟周方正Hsiang-Lin LiuF.C. Chou田如君JuChun Tien2019-09-052014-3-112019-09-052013http://etds.lib.ntnu.edu.tw/cgi-bin/gs32/gsweb.cgi?o=dstdcdr&s=id=%22GN0699410149%22.&%22.id.&http://rportal.lib.ntnu.edu.tw:80/handle/20.500.12235/102779Li2CuO2晶格結構的主要基礎為一個共邊鏈的CuO2。鋰離子沿c軸方向與CuO2交錯堆疊成一正交晶系結構，其晶格常數為a = 3.66 Å，b = 2.86 Å，c = 8.94 Å，銅-氧-銅間的鍵角為93°。此系統具反鐵磁性質，其尼爾溫度約在 TN ~ 9 K，在2.6 K為鐵磁自旋傾斜。Cu2+離子在此系統中為自旋1/2，根據古典海森堡模型理論計算，其有效磁矩為 1.732 μB。然而在實驗上利用居里外斯定律分析磁化率，得到有效磁矩的結果大於1.732 μB，E. M. L. Chung等人從中子繞射實驗發現氧具有自旋，我們進而推論氧缺陷為主因。 　　為了驗證有效磁矩增加是否真為氧缺陷所造成，我們設計了在不同氧壓力和七大氣壓下調變氧分壓，藉以調整氧缺陷在單晶樣品中的含量。利用光學聚焦區浮爐成長單晶樣品，並使用x光粉末繞射能譜、感應耦合電漿質譜儀、熱重分析儀及超導量子干涉磁量儀、分析氧缺陷對樣品物性的影響。實驗結果顯示多餘的磁矩是由氧缺陷所提供。Li2CuO2 has a crystal structure composed of edge-shared CuO2 chains. The lattices constants are a = 3.66 Å, b = 2.86 Å, c = 8.94 Å, and the bond angle of Cu-O-Cu is 93°. This material orders antiferromagnetically below TN ~ 9 K, and canted at 2.6 K. The Cu2+ spin is expected to be 1/2 with effective moment of 1.732 μB. However, the magnetic susceptibility data fitted with Curie-Weiss law always suggest that the effective moment is higher than 1.732 μB, the excess magnetic moment beyond 1.732 µB is likely provided by the oxygen defects, as suggested from the neutron scattering studies by E. M. L. Chung et al. 　　We have synthesized single crystals by using floating-zone method under various oxygen pressures and high pressure of various oxygen partial pressures. This is an effective way to tune the oxygen deficiency level. The effective moment dependence of oxygen defect levels is examined using x-ray powder diffraction (XRPD), inductively coupled plasma-mass spectrometry (ICP-MS), thermo gravimetric analyzer (TGA), and superconducting quantum interference device (SQUID). Our results indicate that excess effective magnetic moments in Li2CuO2 is indeed provided by oxygen defects.Li2CuO2氧缺陷Li2CuO2oxygen defects