Charge Order and Negative Thermal Expansion in V2OPO4
Charge Order and Negative Thermal Expansion in V2OPO4
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DOI：
10.1021/jacs.7b09441
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发表时间：
2018-01-17
影响因子：
15
通讯作者：
Attfield, J. Paul
中科院分区：
文献类型：
--
作者：
Pachoud, Elise;Cumby, James;Attfield, J. Paul
半价氧磷酸盐V_2OPO_4在605 K以下具有长程V_2 ~+/V（3 ~+）电荷有序，并观察到单斜向四斜结构的转变和热膨胀由正向负的转变。轨道聚合物链内的V-V键被认为是热膨胀行为的新开关的关键因素，因为V-V键的损失使得横向氧运动在高温下主导热膨胀。亚铁磁顺序的V2+自旋和V3+自旋下的状态下观察到以下的磁有序转变在164 K，和磁化率测量证据本地自旋配对的相关性，以更高的温度。
The semivalent oxyphosphate V2OPO4 is found to have long-range V2+/V(3+)charge ordering up to 605 K where a monoclinic to tetragonal structural transition and a switch from positive to negative' thermal expansion are observed. V-V bonding within orbital polymer chains is proposed as the key factor in the novel switch of thermal expansion behavior, as loss of V-V bonding enables transverse oxygen motions to dominate the thermal' expansion at high temperatures. Ferrimagnetic order of V2+ spin up and V3+ spin down states is observed below a magnetic ordering transition at 164 K, and susceptibility measurements evidence local spin pairing correlations to higher temperatures.