This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: While chemical bonds usually determine the structure and properties of a material, bonds between neighboring metal atoms can also change as temperature or other conditions change. These changes can lead to unusual electronic and magnetic behaviors.
A new study on Li₀.₅VS₂ shows that bonding between vanadium atoms can reorganize as the material passes through successive structural changes. The study was led by assistant professor Keita Kojima from the Graduate School of Environment, Life, Natural Science and Technology at Okayama University in Japan, along with professor Naoyuki Katayama from Okayama University. The study is published in the journal Chemistry of Materials.
Murphy and his co-workers showed that Li₀.₅VS₂ was the only composition that exhibited two distinct magnetic phase transitions, whereas only a single transition was observed for cases in which the values of x were 0, 0.33 and 1. This unusual behavior strongly motivated Kojima to investigate the electronic and structural changes associated with these transitions. The researchers identified two successive magnetic phase transitions, occurring near 345 and 140 K.
At high temperatures, the vanadium atoms have a triangular arrangement. At intermediate temperatures, they form zigzag chains, while the material develops a more localized magnetic response. At low temperatures, the vanadium atoms shift again, and their bonds reorganize, accompanied by a sharp decrease in magnetic response.
Importantly, electrical resistivity measurements showed that the compound remains metallic through all three phases. The intermediate-temperature phase is particularly unusual because it combines electrical conductivity with a more localized magnetic response. Structural measurements helped explain this behavior.
In the intermediate-temperature phase, some vanadium atoms move closer together to form zigzag chains. The V–V distances shorten by about 0.2 Å, indicating that the atoms begin to form bonds. However, there are not enough electrons to completely fill all these bonds.
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