中文摘要：

以SrO和CrO2为原料,在高温高压的条件下直接反应生成纯相的K2NiF4结构的Sr2CrO4多晶样品.结构用粉末X射线衍射及GSAS精修表征.磁化率测试显示样品存在一个弱的反铁磁相变,奈尔温度为N=95 K.在奈尔温度以上,磁化率随温度的变化遵循居里-外斯定律.对样品进行了电阻测试,结果显示了样品的绝缘特性.

英文摘要：

Sr2CrO4 with a K2NiF4structure can be synthesized by different methods under ambient pressure and high pressure,while the properties reported are quite different. In this paper, pure phase Sr2CrO4 with K2NiF4 structure is obtained by one-step solid state reaction under high pressure and high temperature. Powders of SrO and CrO2 are used as the starting materials. The Sr2 Cr O4structure at room temperature is determined by powder XRD measurement and GSAS Rietveld refinement. Sr2CrO4 crystal is of tetragonal symmetry with space group 4/ and its lattice parameters = 3 8191 ？ and = 12 5046 ？. There are two oxygen sites, apical O1 and equatorial O2. The CrO6 octahedron is slightly elongated along the-axis, forming a longer bond Cr—O1= 1 9180 ？ and a shorter bond Cr—O2= 1 9096 ？.Temperature dependence of the magnetic susceptibility is measured in the temperature range of 2–300 K under the magnetic field 1 T. A weak antiferromagnetic transition can be seen at N = 95 K. Above N, the susceptibility obeys Curie-Weiss law. The Curie-Weiss fitting gives the Weiss constant =-364 K and the effective magnetic moment eff = 2 9 B, in good agreement with the theoretical value of localized Cr4＋, indicating the localized electronic state.Field dependence of susceptibility has been measured at different temperatures. The magnetic properties here are different from those in the previous reports, and this discrepancy is attributed to the quite different sample synthesis methods. Temperature dependence of electrical resistivity of Sr2CrO4 shows insulating behavior. Activation energy ？is estimated by the relation ∝ exp（？/ B） at temperature range 150–300 K. In the temperature range 150–200 K and 200–300 K the activation energies are ？L = 0 134 e V and ？H = 0 168 e V, respectively. The insulating behavior is consistent with the previous experiment reports and the theoretical calculation, which is possibly attributed to the suppression of orbital degree of freedom, resulting from the elongation of CrO6 oc