Solid-state synthesis of multicomponent equiatomic rare-earth oxides
Solid-state synthesis of multicomponent equiatomic rare-earth oxides
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DOI：
10.1111/jace.16971
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发表时间：
2020-01-07
影响因子：
3.9
通讯作者：
Zhuravleva, Mariya
中科院分区：
文献类型：
--
作者：
Pianassola, Matheus;Loveday, Madeline;Zhuravleva, Mariya
多组分稀土氧化物中相的形成取决于组成、烧结气氛和冷却速率的组合。采用固态烧结法合成了由Ce、Gd、La、Nd、Pr、Sm和Y氧化物以等原子比例的各种组合组成的多晶陶瓷。研究了成分、烧结气氛和冷却速度对相形成的影响。以3.3摄氏度/分钟的缓慢冷却获得了单一的立方或单斜结构，证实稀土氧化物遵循与过渡金属高熵氧化物不同的结构稳定过程。在氧化性气氛中，Ce和Pr都诱导立方结构，而在惰性或还原性气氛中只有Ce起作用。不含Ce或Pr的样品形成单一的单斜结构。当陶瓷在另外的气氛中退火时，在初始合成时形成的结构可以转化为不同的结构。还研究了五阳离子组合物的相演变作为烧结温度的函数。用作原料的二元氧化物在1450摄氏度的空气中完全溶解成单一的立方结构。
Phase formation in multicomponent rare-earth oxides is determined by a combination of composition, sintering atmosphere, and cooling rate. Polycrystalline ceramics comprising various combinations of Ce, Gd, La, Nd, Pr, Sm, and Y oxides in equiatomic proportions were synthesized using solid-state sintering. The effects of composition, sintering atmosphere, and cooling rate on phase formation were investigated. Single cubic or monoclinic structures were obtained with a slow cooling of 3.3 degrees C/min, confirming that rare-earth oxides follow a different structure stabilization process than transition metal high-entropy oxides. In an oxidizing atmosphere, both Ce and Pr induce a cubic structure, while only Ce plays that role in an inert or reducing atmosphere. Samples without Ce or Pr develop a single monoclinic structure. The structures formed at initial synthesis may be converted to a different one, when the ceramics are annealed in an additional atmosphere. Phase evolution of a five-cation composition was also studied as a function of sintering temperature. The binary oxides used as raw materials completely dissolve into a single cubic structure at 1450 degrees C in air.