Abstract

75 mol % LiF + 25 mol % SmF₃ eutectic composite is obtained by fusing components in a CF₄ atmosphere. The composite is multiphase and consists of β-SmF₃ (sp. gr. Pnma, a = 6.6703(2) Å, b = 7.0557(2) Å, c = 4.4005(2) Å), LiF (sp. gr. \(Fm\bar {3}m\), a = 4.0234(3) Å), and a small amount (up to 4.5% of the total trifluoride content) of α-SmF₃ (sp. gr. \(P\bar {3}c1\), a = 6.946(1) Å, c = 7.136(1) Å). The conductometric measurements are carried out in a heating–cooling cycle in the range of 463–827 K. A first-order phase transition is detected upon heating at T_tr = 763 ± 15 K, which increases the conductivity σ_dc of the composite by a factor of ~10. After the experiment, the α-SmF₃ phase content in the composite increases by a factor of almost 3. According to the differential scanning calorimetry data, the polymorphic transition in pure SmF₃ component occurs at T_β−α = 764.6 ± 0.2 K. The first-order transition in the composite is assigned to the polymorphic β-SmF₃ → α-SmF₃ transition. Upon cooling, a reverse transition from the high-temperature α-SmF₃ (LaF₃ type) to the low-temperature form β-SmF₃ (β-YF₃ type) is kinetically retarded. The enthalpy of σ_dc activation for α-SmF₃ is ΔH_σ = 0.37 ± 0.05 eV.

中文翻译：

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75LiF + 25SmF 3共晶复合物和SmF 3的离子电导率，接近多态α-β转变

摘要

通过在CF ₄气氛中熔融组分而获得75mol％的LiF + 25mol％的SmF ₃共晶复合物。该复合材料是多相和组成的β-SMF ₃（比重=晶Pnma，一个= 6.6703（2）埃，b = 7.0557（2）埃，c ^ = 4.4005（2）埃），LIF（比重= \ （FM \巴{3}米\） ，一个= 4.0234（3）埃），和少量（总三氟化含量高达4.5％）α-SMF ₃（比重= \（P \巴{3} c1 \），a = 6.946（1）Å，c= 7.136（1）Å）。电导测量在一个加热-冷却循环中463-827 K. A的范围内进行时，在加热中检测的一阶相变Ť _TR = 763±15 K，这增加了导电率σ_的直流通过该复合材料的约10倍 在实验后，α-SMF ₃在复合的增加相含量的几乎3.按照差示扫描量热法数据的一个因素，在纯SMF的多晶型转变₃成分发生在Ť _β-α = 764.6±0.2 K.在复合材料中的一阶过渡分配给多态β-SMF ₃ →α-SMF ₃过渡。冷却后，从高温α-SMF的反向过渡₃（LAF ₃型），以低温形式β-SMF ₃（β-YF ₃型）在动力学延迟。σ的焓_直流活化α-SMF ₃是Δ ħ _σ = 0.37±0.05电子伏特。