Related Experiment Video
Updated: Apr 5, 2026
08:55
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
9.0K
Low temperature structural anomalies arising from competing exchange interactions in pyrochlore Nd2Ru2O7 probed by
Shi-Wei Chen1, Shao-Wei Fu, Chih-Wen Pao
1National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan. jmchen@nsrrc.org.tw.
Physical Chemistry Chemical Physics : PCCP
|August 25, 2015
Summary
Structural instability in pyrochlore Nd2Ru2O7 at low temperatures is linked to atomic disorder. This disorder drives spin frustration by competing magnetic interactions, offering new insights into its magnetic state.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Solid State Chemistry
Background:
- Pyrochlore materials exhibit complex magnetic behaviors.
- Understanding the interplay between structure and magnetism is crucial for novel material design.
Purpose of the Study:
- To quantitatively determine the structural parameters of pyrochlore Nd2Ru2O7 and their temperature dependence.
- To investigate the origin of structural instability and its correlation with magnetic properties.
Main Methods:
- X-ray Diffraction (XRD) and Extended X-ray Absorption Fine Structure (EXAFS) data fitting.
- Analysis of lattice parameters, bond lengths, bond angles, and atomic disorder.
Main Results:
- Anomalous expansion of lattice parameter and Ru-O bond length at low temperatures.
- Evidence of static disorder of Ruthenium (Ru) atoms, indicated by increased mean square fluctuation.
- Correlation between static disorder, decreased Ru-O-Ru bond angle, and short-range ferromagnetic coupling.
Conclusions:
- Spin frustration in Nd2Ru2O7 arises from competing ferromagnetic and antiferromagnetic interactions.
- Spin frustration induces structural instability at the atomic scale.
- This study provides a new perspective on the magnetic state of Nd2Ru2O7 through its structural properties.
Related Concept Videos
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
87
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...
87
01:29Imperfections in Crystal Structure: Non-Stoichiometric Defects
77
Non-stoichiometric defects refer to a type of defect in the crystal structure of a compound where the ratio of its constituent elements deviates from the ideal stoichiometric ratio. There are two main types of non-stoichiometric defects: metal excess defects and metal deficiency defects.Metal excess defects occur when there is a slight surplus of metal ions than what is required by the stoichiometric ratio of the compound. For example, heating a sodium chloride crystal in sodium vapor results...
77
01:29Determination of Crystal Structures
111
In the late 1800s, the revelation that light extended beyond visible wavelengths led to the discovery of X-rays by Wilhelm Roentgen. Recognized as high-energy electromagnetic radiation with short wavelengths, X-rays prompted exploration into their interaction with crystals. Max von Laue proposed in 1912 that the periodic arrangement of atoms, ions, or molecules in crystals would cause them to diffract X-rays, a hypothesis confirmed through experiments with copper sulfate and zinc sulfide...
111
01:10X-ray Diffraction of Biological Samples
5.2K
X-ray diffraction or XRD is an analytical tool that utilizes X-rays to study ordered structures such as crystalline organic and inorganic samples, polycrystalline materials, proteins, carbohydrates, and drugs.
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal...
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal...
5.2K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
49.7K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
49.7K
02:58Crystal Field Theory - Octahedral Complexes
31.8K
Crystal Field Theory
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...
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...
31.8K