Sm_(2)Y_(1-x)Al_(x)TaO_(7)陶瓷材料的热物理性能

Thermophysical Properties of Sm_(2)Y_(1-x)Al_(x)TaO_(7) Ceramics

以高纯度Al_(2)O_(3)、Y_(2)O_(3)、Sm_(2)O_(3)和Ta_(2)O_(5)为原材料,采用高温烧结方法制备了Sm_(2)Y_(1-x)Al_(x)TaO_(7)系列陶瓷材料,对其晶体结构、显微组织、元素组成、热导率和热膨胀性能进行了系统研究。结果表明,除Sm_(2)Y_(0.5)Al_(0.5)TaO_(7)具有焦绿石结构之外,其余三种氧化物均具有单一的萤石晶体结构。其块体材料相对致密度均在90%以上,晶界清晰,各元素摩尔比与其化学式基本一致。由于Al^(3+)和Y^(3+)之间较大的离子半径和原子量差别,增大了对声子的散射,其热传导性能随着Al_(2)O_(3)含量的增加而降低。虽然Al_(2)O_(3)含量增加降低了其热膨胀系数,其大小与YSZ基本相当,所制备陶瓷在室温至1400℃范围内具有良好的相稳定性能。

The high-purity Al_(2)O_(3),Y_(2)O_(3),Sm_(2)O_(3)and Ta_(2)O_(5)were utilized as raw materials to prepare the Sm_(2)Y_(1-x)Al_(x)TaO_(7)series ceramic materials through a high-temperature sintering method.Their crystal structure,microstructure,elemental composition,thermal conductivity,and thermal expansion properties were systematically studied.The results indicate that except for Sm_(2)Y_(0.5)Al_(0.5)TaO_(7),which has a pyrochlore structure,the other three oxides exhibit a single fluorite crystal structure.The relative density of the obtained dense samples exceeded 90%,displaying clear grain boundaries,and the molar ratios of elements were consistent with their chemistry formulas.Because of the large disparities in ionic radius and atomic weight between Al3+and Y3+,phonon scattering is amplified;nevertheless,as the Al_(2)O_(3)concentration increases,the thermal conductivity of Sm_(2)Y_(1-x)Al_(x)TaO_(7)falls.Although an increase in Al_(2)O_(3)concentration reduces the thermal expansion coefficient,the value remains equivalent to YSZ.Additionally,the prepared ceramics exhibit excellent phase stability at the temperature range from room temperature to 1400℃.