Related Experiment Video
Updated: May 30, 2026
Radio Frequency Magnetron Sputtering of GdBa2Cu3O7−δ/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 (STO) Single-crystal Substrates
Published on: April 12, 2019
Structural transition, electrical and magnetic properties of the B-site Co doped Sr(14)Cu(24)O(41) compounds
Jun Wang1, Ying Lin, Huamin Zou
1Key Laboratory of Acoustic and Photonic Materials and Devices of the Ministry of Education, Department of Physics, Wuhan University, Wuhan 430072, People's Republic of China. Center for Electron Microscopy, Wuhan University, Wuhan 430072, People's Republic of China.
Abstract:
The effect of Co substitution for Cu on the structure and physical properties of Sr(14)(Cu(1-x)Co(x))(24)O(41) compounds was studied by analyzing the selected-area electron diffraction and convergent-beam electron diffraction patterns, and by measuring the magnetic susceptibility, the electrical resistivity and Raman spectra. It is found that the space group of the CuO(2) chain is changed from Amma to Ammm upon Co doping, but the structure of the Cu(2)O(3) ladder remains unchanged. This indicates that the displacement between two neighboring CuO(2) chains has disappeared due to Co doping. Once a small amount of Co ions are doped into the compound, exceptional changes in the Weiss temperature and in the number of dimers occur. The remarkable increase in the absolute value of the Weiss temperature indicates that the antiferromagnetic interaction in CuO(2) chains becomes very strong due to Co doping. The increase in the Curie coefficient and the number of dimers implies that the Co doping causes Zhang-Rice singlets in the chains to be decoupled into free spins Cu(2+) and holes. Then, the free spins Cu(2+) are coupled into dimers, and the holes transfer from chains to ladders, which causes the resistivity to decrease when the Co dopant concentration is low (x<0.10). When the Co dopant concentration is high (x>0.10), some Co ions are directly substituted for the Cu ions in the ladders, which results in an increase in resistivity with increasing Co dopant content.
Related Concept Videos
02:58Properties of Transition Metals
03:02Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
02:42Valence Bond Theory
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
04:00Periodic Classification of the Elements
02:34Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...