材料科学
氧烷
X射线光电子能谱
X射线吸收光谱法
铁电性
价(化学)
扩展X射线吸收精细结构
兴奋剂
拉曼光谱
吸收光谱法
吸收边
分析化学(期刊)
光谱学
K-边
X射线吸收精细结构
结晶学
核磁共振
化学
带隙
光学
量子力学
光电子学
物理
电介质
色谱法
有机化学
作者
M. Arshad,Wasi Khan,Parasmani Rajput,Manvendra Kumar,M. Abushad,Shahid Husain
标识
DOI:10.1016/j.ceramint.2022.01.302
摘要
In this report, the local structure geometry of BaTi1-xNixO3 (0.0 ≤ x ≤ 0.06) ceramics has been studied through synchrotron based x-ray-absorption spectroscopy, measured at the Ti K, Ba L3 and Ni K-edges at room temperature. The x-ray absorption near edge spectroscopy (XANES) at Ti K-edge confirms the TiO6 octahedron geometry of Ti atom due hybridization between Ti(3d)-O(2p) orbitals and signifies the non-centrosymmetric nature of BaTiO3 samples. However, Ti–O off-center displacement (non-centrosymmetric) is disturbed under the effect of Ni doping as a result of oxygen vacancies formation. More interestingly, XANES studies at Ni K-edge ensure successful substitution of Ni in BaTiO3 as Ni2+ ions. Extended x-ray absorption fine structure (EXAFS) data at Ni K-edge have been fitted to estimate pertinent local structural parameters of the Ni–O, Ni–Ba, Ni–Ti and Ni–Ni shells (viz. bond lengths and disorder parameters) and it also reveal that the structural disorders around the Ti sites in the doped BaTiO3 expand with Ni doping. The mixed-valence states of titanium ion, i.e., Ti4+ and Ti3+ in the doped samples were established with the x-ray photoelectron spectroscopy (XPS). Moreover, XPS divulges the creation of oxygen vacancies due to Ni doping in BaTiO3 matrix. The complementary information about the lattice vibration is analyzed through Raman studies that approve the softening of the transverse optical (TO) mode present at 515 cm−1. The temperature dependent ferroelectric studies affirm that the ferroelectricity vanishes in the doped samples due to the decrement in the off-center displacement between the Ti4+ and O2− ions in the TiO6 octahedral geometry. Differential thermal analysis (DTA) exhibits a ferroelectric tetragonal to para-electric cubic phase transition in the pristine as well as Ni doped BaTiO3 samples.
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