摘要
The phase transition of a new compound Sr_2CdWO_6 has been investigated by means ofdifferential thermal analysis (DTA), X-ray powder diffraction, precise measurement of latticeparameters and other methods. It has been discovered that the compound has a first-orderdisplacive phase transition. The low-temperature-phase α-Sr_2CdWO_6 belongs to the orthor-hombic crystal system with space group Pmm2. Its lattice parameters at room temperatureare: a=8.1673A, b=5.7436A, c=5.8188A, the measured density is D_m=7.01g/cm^3, andeach unit cell contains two formula weights. The high-temperature-phase β-Sr_2CdWO_6 be-longs to the cubic system, with space group Fm3m and lattice parameter a=8.201A at860℃, and Z=4. The crystal structures of α-Sr_2CdWO_6 and β-Sr_2CdWO_6 have been determined by meansof the X-ray polycrystal method. The phase transition mechanism and the distortion degreeare investigated.
The phase transition of a new compound Sr<sub>2</sub>CdWO<sub>6</sub> has been investigated by means ofdifferential thermal analysis （DTA）, X-ray powder diffraction, precise measurement of latticeparameters and other methods. It has been discovered that the compound has a first-orderdisplacive phase transition. The low-temperature-phase α-Sr<sub>2</sub>CdWO<sub>6</sub> belongs to the orthor-hombic crystal system with space group Pmm2. Its lattice parameters at room temperatureare: a=8.1673A, b=5.7436A, c=5.8188A, the measured density is D<sub>m</sub>=7.01g/cm<sup>3</sup>, andeach unit cell contains two formula weights. The high-temperature-phase β-Sr<sub>2</sub>CdWO<sub>6</sub> be-longs to the cubic system, with space group Fm3m and lattice parameter a=8.201A at860℃, and Z=4. The crystal structures of α-Sr<sub>2</sub>CdWO<sub>6</sub> and β-Sr<sub>2</sub>CdWO<sub>6</sub> have been determined by meansof the X-ray polycrystal method. The phase transition mechanism and the distortion degreeare investigated.
