Tuning room temperature T-p and MR of La1-y(Cay-xSrx)MnO3 polycrystalline ceramics by Sr doping
Tuning room temperature T-p and MR of La1-y(Cay-xSrx)MnO3 polycrystalline ceramics by Sr doping
复制标题
Sr掺杂调控La1-y(Cay-xSrx)MnO3多晶陶瓷的室温T-p和MR
DOI：
10.1016/j.ceramint.2016.12.121
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发表时间：
2017
影响因子：
5.2
通讯作者：
Liu Xiang
中科院分区：
文献类型：
--
作者：
Zhao Shuang;Yue Xuejiao;Liu Xiang
采用Sol−凝胶法制备了x=0，y/2 5，2y/2 5，3y/2 5，4y/2 5，y/3，y/2，2 y/3的多晶Sr−掺杂La1-y(Cay-xSrx)MnO3(LCSMO，y=3/8)陶瓷。X射线衍射图结果表明，所有样品都是单相的，没有任何杂质。当锶含量(X)等于或大于y/2时，样品的结构由正交相(PnmA空间群)向菱方相(R3̅c空间群)转变。随着x含量的增加，样品的电阻温度系数和磁阻温度系数逐渐减小。然而，LCSMO(x=4y/25)样品的金属-绝缘体转变温度(Tp)在300K时分别达到300.4 K和12%，这意味着LCSMO材料可以作为光电(非制冷测辐射热计或红外探测器等)的候选材料。或磁性设备(非制冷磁性传感器等)在室温下。结果表明，在LCSMO(y=3/8)多晶陶瓷中，用Sr2+离子取代了钙离子的位置，观察到了Tp和MR的室温调制。这导致了LCSMO陶瓷中A−位平均阳离子半径的增大，并通过Mn3+和Mn4+离子之间的双交换提高了Mn4+离子的浓度，从而提高了LCSMO陶瓷的电磁性能。
Abstract Polycrystalline Sr− doped La 1-y (Ca y-x Sr x) MnO 3 (LCSMO, y= 3/8) ceramics with x= 0, y/25, 2y/25, 3y/25, 4y/25, y/3, y/2, and 2y/3 were prepared by sol− gel methods. X-ray diffraction patterns results indicated that all the bulk samples were single phase without any impurities. The structure of the samples transformed from orthorhombic phase (space group of Pnma) to rhombohedral phase (space group of R 3 ̅ c) when the Sr content (x) was equal to or greater than y/2. With the increasing of x content, the temperature coefficient of resistance (TCR) and magnetic resistance (MR) decreased gradually. However, the metal to insulator transition temperature (T p) and the MR reached at 300.4 K and 12% at 300 K for the LCSMO (x= 4y/25) sample, respectively, which meant the LCSMO material could be used as a candidate for photoelectric (uncooled bolometer or infrared detectors, etc.) or magnetic devices (uncooled magnetic sensors, etc.) at room temperature. Visibly, the results indicated that the room temperature modulation of T p and MR was observed when the site of the Ca 2+ ion was substituted by the Sr 2+ ion in LCSMO (y= 3/8) polycrystalline ceramics. This gave rise to the increasing size of the A− site average cationic radius< r A> and improving of the Mn 4+ ion concentration through double exchange between the Mn 3+ and Mn 4+ ions, leading to enhance the electrical and magnetic properties of LCSMO ceramics.