Phase transformation from tetragonal-phase to cubic-phase due to addition of titanium in lanthanum sesquisulfide
Phase transformation from tetragonal-phase to cubic-phase due to addition of titanium in lanthanum sesquisulfide
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DOI：
10.1016/j.jallcom.2003.11.082
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发表时间：
2004-07
影响因子：
6.2
通讯作者：
M. Ohta;S. Hirai;S. Morita;T. Nishimura;Y. Uemura
中科院分区：
文献类型：
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作者：
M. Ohta;S. Hirai;S. Morita;T. Nishimura;Y. Uemura
众所周知，三硫化镧（La 2S 3）中的四方相（β相）实际上是La 10 S15 − xOx，其中0≤x≤1。当β-La 2S 3-相在1573 K左右转变为高温α-相（γ-相）时，La 10 S14 O-相在很宽的温度范围内稳定在β-相中。我们报道了由于钛的加入，从La_（10）S_（14）O相到γ相的相变。在1113 K的二硫化碳气氛中，通过硫化氧化镧制备了La 10 S14 O粉体。在923 ~ 1773 K的温度范围内，对La_（10）S_（14）O和Ti的混合粉末进行了热压烧结和脉冲电流烧结，烧结时间为3.6ks。当未添加添加剂的烧结体保持β相时，添加8 wt. Ti在1573 K转变为γ单相。此外，在初始阶段形成LaS相。由于在从β-La 2S 3-相到γ-相的相变中没有形成LaS-相，显然，由于钛的添加，LaS-相在相变中起重要作用。
It is well known that the tetragonal-phase (β-phase) in lanthanum sesquisulfide (La2S3) is actually La10S15−xOxwith 0≤x≤1. While the β-La2S3-phase transforms to the high temperature cubic-phase (γ-phase) at around 1573K, the La10S14O-phase is stabilized in the β-phase over a wide range of temperatures. We report the phase transformation from the La10S14O-phase to the γ-phase due to the addition of titanium. The La10S14O powder was synthesized by sulfurizing lanthanum oxide in carbon disulfide gas at 1113K. The powder mixture of the La10S14O and Ti was sintered by hot-pressing or by pulsed electric current sintering in the temperature range from 923 to 1773K for 3.6ks. While the sintered compact with no addition maintains the β-phase, the sintered compact with 8wt.% Ti transforms to the γ single-phase at 1573K. Moreover, the LaS-phase is formed at the initial stage. Since the LaS-phase is not formed in the phase transformation from the β-La2S3-phase to the γ-phase, it is obvious that the LaS-phase plays an important role in the phase transformation due to the addition of titanium.