Cr_(2(1-x))(HfMg)_(x)Mo_(3)O_(12)固溶体相变及热膨胀性能的研究

Phase Transition and Negative Thermal Expansion of Cr_(2(1-x))(HfMg)_(x)Mo_(3)O_(12)

利用固相烧结法制备出Cr_(2(1-x))(HfMg)_(x)Mo_(3)O_(12)系列材料,能有效降低Cr_(2)Mo_(3)O_(12)的相变温度,并改善其热膨胀性能。研究了(HfMg)^(6+)掺杂量对材料相变和热膨胀的影响。结果表明,该系列材料单斜相到正交相的相变温度明显降低,随着(HfMg)^(6+)参杂量的增加,转变为正交相结构后材料的热膨胀系数逐渐减小接近零膨胀。当x≥0.7时,该材料在室温下展示为宽温度范围的近零膨胀性,意味着该材料在诸多领域都有潜在的应用前景。

Solid solutions of Cr_(2(1-x))(HfMg)_(x)Mo_(3)O_(12) are synthesized by solid state reaction which can effectively reduce the phase-transition temperature ofCr_(2)Mo_(3)O_(12) and improve its thermal expansion property.The effects of(HfMg)^(6+)incorporation on the phase transition and thermal expansion are investigated.It is shown that the monoclinic-to-orthorhombic phase transition temperature decreases significantly and the coefficient of thermal expansion(CTE)of the orthorhombic becomes less negative and close to zero with increasing the content of(HfMg)^(6+).A near zero thermal expansion covering the case at room temperature(RT)is achieved for the solid solutions with x≥0.7,implying potential applications of this material in many fields.