La_(2-x)Pr_xNiO_(4+δ)体系低频内耗研究  

Low-Frequency Internal Friction Research on La_(2-x)Pr_xNiO_(4+δ) System

作　　者：陈志军[1,2] 吴修胜[3] 刘卫[2] 

机构地区：[1]安徽省绩溪中学,安徽宣城245300 [2]中国科学技术大学中国科学院能源转换材料重点实验室,安徽合肥230026 [3]安徽建筑大学材料与化学工程学院,安徽合肥230022

出　　处：《中国稀土学报》2015年第5期602-608,共7页Journal of the Chinese Society of Rare Earths

基　　金：国家自然科学基金项目(10574123;11204406)资助

摘　　要：利用内耗技术对La2-xPrxNi O4+δ(0≤x≤2.0)体系额外氧的状态进行了深入研究。La2-xPrxNi O4+δ(0≤x≤2.0)系列样品的XRD数据拟合计算得出:当x小于等于0.75时,体系为四方结构,而当x大于0.75时,体系转变为正交结构。通过对体系低频内耗和模量的测量研究发现,当0≤x≤0.75时,样品只存在一个弛豫内耗峰(P1峰),其峰值随x值增大而增大,与额外氧的浓度成正相关;当1.0≤x≤2.0时,样品中存在两个弛豫内耗峰,分析研究表明:高温侧内耗峰P1对应着前面发现的内耗单峰,它是由ab面额外氧对的取向弛豫运动引起的,在这里该内耗峰峰值随x值增大而减小,显然是受到额外氧的三维有序结构形成的影响。低温侧内耗峰峰P2可能与额外氧对的新的组态运动方式有关。Internal friction techniques were used to investigate the excess oxygen state of La2-xPrxNi O4＋δ （0 ≤x≤ 2.0） system. The XRD data of La2-xPrxNi O4＋δ samples were fitting calculated. For x~〈0.75, the system is tetragonal structure. For x 〉 0.75, the system is orthogonal structure. The temperature dependence of low-frequency internal friction and shear modulus of La2-xPrxNi O4＋δ （0 ≤ x ≤2.0） samples were studied. There was one relaxation internal friction peak P1 in all simples, which was due to the orientation migration of excess oxygen pairs in ab plane. The peak Pt height increased with x increasing when x≤0.75, the height decreased with x increasing when x≥1. 0, which may be affected by the three-dimensional （3D） ordering process of the excess oxygen. For 1.0≤x ≤2.0, another relaxation internal friction peak P2 at the low temperature side of P1 may be related to the new con- figuration of the excess oxygen.

关 键 词：La2-xPrxNiO4+δ 额外氧 内耗 稀土 

分 类 号：O48[理学—固体物理]