Mossbauer Spectroscopic Studies of Super-ionic Conductors

1. ^<197>Au Mossbauer光谱仪和X射线粉末衍射（XRD）已被应用于混合系统的超离子导体，如AgI-AuI和Ag_2XAu_2X（X=S、Se和Te）。这些系统展示了在不同热分析（DTA）曲线中的内热峰值，从结构相转换中得到的结果。来自<197>16 K的gamma-AgAuI_2中的^ Au Mossbauer光谱，I-Au-I键比AuI晶体中的复合物更具有关联性，建议Gamma-AgAuI_2中的Ag^+[AuI_2]^-。^<197>Au Mossbauer spectra在Ag_3AuX_2的16 K（X=S， Se， and Te）建议黄金原子，由两个电荷原子进行线性协调，存在于单一音调，以及在S， Se和Te顺序中X-AU-X键增加的常见特征。The ^<125>Te Mossbauer spectra suggest that the tellurium atoms are substantially ionic for both Ag_2 Te and Ag_3 AuTe_2.2。TeO_2和SnO_2对Gelta-Bi_2 O_3（氧离子导体）的稳定性使用XRD和^<125>Te Mossbauer光谱仪进行了调查。A composite oxide of 3 Bi_2 O_3·2 TeO_2 composition exhibited a endfothermic peak at 815？C in the DTA curve with a wieght loss of 1. 7%。氧化物的低温度阶段被分配到了orthorhombic Bi_6Te_2O_<15>，在那里的碲原子位于Te（VI）的状态。由quenching发现的高温度相位被识别为立方体Bi_6Te_2O_<13>（一种氧-deficient fluorite结构，存在于Te（IV）状态中。

1. ^<197>Au Mossbauer spectroscopy and X-ray powder diffraction(XRD)have been applied for super-ionic conductors of mixed systems such as AgI-AuI and Ag_2XAu_2X(X=S, Se, and Te). These systems showed endothermic peaks in their differential thermal analysis(DTA)curves, resulting from the structural phase transitions. From the ^<197>Au Mossbauer spectrum at 16K of gamma-AgAuI_2, the I-Au-I bond is more covalent in the compound than in the AuI crystal, suggesting that gamma-AgAuI_2 consists of Ag^+[AuI_2]^-. The ^<197>Au Mossbauer spectra at 16K of Ag_3AuX_2(X=S, Se, and Te)suggest that the gold atoms, linearly coordinated by two chalcogen atoms, exist as monovalent cations, and the covalent character of the X-AU-X bonds increase in the order of S, Se, and Te. The ^<125>Te Mossbauer spectra suggest that the tellurium atoms are substantially ionic for both Ag_2Te and Ag_3AuTe_2.2. The stabilization of gelta-Bi_2O_3 (oxygen-ion conductor) by TeO_2 and SnO_2 has been investigated by using XRD and ^<125>Te Mossbauer spectroscopy. A composite oxide of 3Bi_2O_3・2TeO_2 composition exhibited a endfothermic peak at 815ﾟC in the DTA curve with a wieght loss of 1.7%. The low temperature phase of the oxide was assigned to the orthorhombic Bi_6Te_2O_<15>, in which the tellurium atom was in the state of Te(VI). The high temperature phase obtained by quenching was identified to the cubic Bi_6Te_2O_<13> (a oxygen-deficient fluorite structure, in which tellurium existed in the state of Te(IV).