Open AccessLocal structural studies of the cubic Cd 1– x Ca x O system through Cd K ‐edge extended X‐ray absorption spectroscopic studies
Author(s) -
Srihari Velaga,
Sridharan V.,
Nomura Masaharu,
Sastry V. Sankara,
Sundar C. S
Publication year - 2012
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049512018419
Subject(s) - solid solution , diffraction , x ray crystallography , chemistry , absorption (acoustics) , crystallography , analytical chemistry (journal) , absorption edge , x ray , k nearest neighbors algorithm , physics , condensed matter physics , optics , band gap , organic chemistry , chromatography , artificial intelligence , computer science
Cd K ‐edge extended X‐ray absorption fine‐structure spectroscopic studies were carried out on Cd 1– x Ca x O (0 ≤ x ≤0.9) solid solutions and the first and second nearest neighbour (NN) distances and their mean square relative displacement σ 2 were estimated. The first NN distance, d Cd–O ( x ), was found to be smaller than its expected value, a ( x )/2, obtained from the X‐ray diffraction measurements. It increases monotonically and non‐linearly with a negative curvature, comparable with that of the a ( x ) value variation. The variation σ 2 of the 1NN with x is consistent with a disordered solid solution model. The 2NN distances d Cd–Cd ( x ) and d Cd–Ca ( x ) are found to follow the average values obtained by X‐ray diffraction with d Cd–Ca ( x ) > d Cd–Cd ( x ). From detailed analysis it is argued that the solid solution exhibits a bimodal distribution of the 1NN distances, d Cd–O ( x ) and d Ca–O ( x ), and that the system belongs to a persistent type.