Distortion and Charge Density Wave in the Ga Square Net Coupled to the Site Occupancy Wave in YCo0.88Ga3Ge

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• 作者：Danielle L. Gray ; Melanie C. Francisco ; Mercouri G. Kanatzidis
• 刊名：Inorganic Chemistry
• 出版年：2008
• 出版时间：August 18, 2008
• 年：2008
• 卷：47
• 期：16
• 页码：7243-7248
• 全文大小：293K
• 年卷期：v.47,no.16(August 18, 2008)
• ISSN：1520-510X

文摘

YCob>0.88b>Gab>3b>Ge has an incommensurately modulated structure that was solved with (3 + 1)D superspace techniques. YCob>0.88b>Gab>3b>Ge crystallizes in the orthorhombic superspace group Immm(α00)00s with unit cell constants of a = 4.1639(4), b = 4.1639(4), c = 23.541(2) Å and a modulation vector of q = 0.3200(4)a* at 293 K. The incommensurate modulation, which creates a very large supercell (∼25 fold), arises from a charge density wave (CDW) in the square net of Ga atoms that is coupled with a site occupancy wave (SOW) of Co atoms. The distorted Ga net features polygallide ribbons, chains, as well as single atoms. Temperature dependent crystallographic studies of the structure from 100−500 K indicate that the CDW is “locked in”. Electrical conductivity and thermopower measurements in the temperature range of 300−500 K show that YCob>0.88b>Gab>3b>Ge is a poor metal.