Preparation of Multiple-Cation alpha-SiAlON Ceramics Containing Lanthanum
Preparation of Multiple-Cation alpha-SiAlON Ceramics Containing Lanthanum
复制标题
含镧多阳离子α-SiAlON陶瓷的制备
DOI：
10.1111/j.1151-2916.1999.tb01750.x
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发表时间：
2004
影响因子：
3.9
通讯作者：
M. Hoffmann
中科院分区：
文献类型：
--
作者：
H. Mandal;M. Hoffmann
直到最近，人们才接受具有1.03 A的离子半径（r）的Ce 3+阳离子太大而不能形成α-SiAlON结构。然而，最近的研究表明，在1800°C下烧结后，铈阳离子可以通过以600°C/min的速率淬火并入α-SiAlON中。到目前为止，对于r= 1.06 A的La 3+阳离子，没有观察到α-SiAlON形成。在目前的工作中，有La 3+物种作为掺杂剂阳离子在α-SiAlON的可能性进行了研究，通过使用单独的La 2 O3或与CaO或Yb 2 O3等摩尔的混合物。将所得材料在1450°C的温度下热处理720 h，以使晶界玻璃析晶成晶相，并观察α→β SiAlON转变。对用单一阳离子致密化的样品的X射线衍射表明，单独的La 3+阳离子不形成α-SiAlON;相反，它形成具有s-SiAlON相的N相（La 3Si 8 O 4 N11）。在多种阳离子的情况下，α-SiAlON仅作为基质相观察到。能量色散X射线测量表明，La 3+离子可以被容纳到α-SiAlON结构中，并且在较低温度下这种结构也不会转变为β-SiAlON。
Until recently, it was accepted that Ce3+ cations, with an ionic radius (r) of 1.03 A, were too large to form an α-SiAlON structure. However, more-recent studies have shown that cerium cations can be incorporated into α-SiAlON via quenching at a rate of 600°C/min, after sintering at 1800°C. Thus far, no α-SiAlON formation has been observed for La3+ cations with r= 1.06 A. In the present work, the possibility of having the La3+ species as a dopant cation in α-SiAlON has been investigated by using La2O3 alone or in equimolar mixtures with CaO or Yb2O3. The resulting materials have been heat-treated at a temperature of 1450°C for up to 720 h to devitrify the grain-boundary glass into crystalline phases and also to observe the α→β SiAlON transformation. X-ray diffractometry on samples that were densified with single cations revealed that the La3+ cation alone does not form an α-SiAlON; rather, it forms the N-phase (La3Si8O4N11) with a s-SiAlON phase. In the case of multiple cations, α-SiAlON was observed only as a matrix phase. Energy-dispersive X-ray measurements have proven that La3+ cations can be accommodated into the α-SiAlON structure and this structure also does not transform to β-SiAlON at lower temperatures.