High temperature structural investigation of the delafossite type compound CuAlO2
High temperature structural investigation of the delafossite type compound CuAlO2
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DOI：
10.1016/0022-4596(82)90193-1
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发表时间：
1982-02
影响因子：
3.3
通讯作者：
T. Ishiguro;N. Ishizawa;N. Mizutani;M. Kato
中科院分区：
文献类型：
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作者：
T. Ishiguro;N. Ishizawa;N. Mizutani;M. Kato
用单晶高温X射线衍射法测定了CuAlO2在295、450、600、750、900和1200K温度下的晶体结构参数。各向异性细化导致在各自温度下的常规R值分别为0.021、0.027、0.029、0.030、0.032和0.036。CuAlO2晶体在295K时具有菱形空间群R3m，a=2.8584(7)，c=16.958(3)ä，Z=3.尺寸a的平均热膨胀系数为11.0×10−6 K−1，约为c的4.1×10−6 K−1的3倍.在该结构中，AlO 6八面体通过OO边连接在一起，形成垂直于c轴的AlO2层，厚度相当于八面体的高度.随着温度的升高，AlO_6八面体沿基面方向膨胀，而沿c轴几乎不发生膨胀。位于AlO2层之间的铜原子在热振动中表现出很大的各向异性行为。在1200K时，铜原子在基面上的温度因子变得很大(0.044？2)，但垂直于c的温度因子与平行于c的温度因子的比值随温度的升高变化不大。
Crystal structure parameters were determined for the delafossite type compound CuAlO 2 at 295, 450, 600, 750, 900, and 1200 K with single crystal high temperature X-ray diffraction technique. Anisotropic refinements result in conventional R values of 0.021, 0.027, 0.029, 0.030, 0.032, and 0.036 at respective temperatures. Crystals of CuAlO 2 have the rhombohedral space group R 3 m with a= 2.8584 (7), c= 16.958 (3) Å and Z= 3 at 295 K. The mean thermal expansion coefficient for the dimension a is 11.0× 10− 6 K− 1 about three times larger than 4.1× 10− 6 K− 1 for c. In the structure, the AlO 6 octahedra are linked by their O O edges and form AlO 2 layers perpendicular to the c axis with the thickness corresponding to the height of an octahedron. With increasing temperature, the AlO 6 octahedra expand along the directions of the basal plane, while expansion scarcely occurs along the c axis. The Cu atom lying between the AlO 2 layers shows a large anisotropic behavior in the thermal vibration. The temperature factor for Cu atom in the basal plane becomes very large (0.044 Å 2) at 1200 K, but the ratio of the temperature factor perpendicular to c to that parallel to c does not change appreciably with increasing temperature.