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无机材料学报

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K2Ln(NO3)5·2H2O(Ln=La,Ce,Pr,Nd,Sm)的晶体生长和热重-差热分析研究

董文庭; 张洪杰; 苏锵   

  1. 中国科学院长春应用化学研究所; 稀土化学与物理开发实验室 长春 130022
  • 收稿日期:1997-11-24 修回日期:1998-01-23 出版日期:1998-12-20 网络出版日期:1998-12-20

Crystal Growth and TG-DTA Properties of K2Ln(NO3)5.2H2O(Ln=La, Ce, Pr, Nd, Sm)

DONG Wen-Ting; ZHANG Hong-Jie; SU Qiang   

  1. Key Laboratory of Rare Earth Chemistry and Physics; Changchun Institute of Applied Chemistry; Chinese Academy of Sciences Changchun 130022 China
  • Received:1997-11-24 Revised:1998-01-23 Published:1998-12-20 Online:1998-12-20

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摘要： 本文生长出了K2Ln（NO3）5·2H2O（Ln=La；Ce；Pr；Nd；Sm）的单晶，并对其进行了晶体结构及差热-热重分析研究．结果表明，K2Ln（NO3）5.2H2O（Ln=La；Ce；Pr；Nd）的晶体属正交晶系，Fdd2空间群．首次生长出KPrN单晶并用直接法解出其晶体结构．解得KPrN的晶胞参数为：a=11．2210（10）A, b=21．411（3）A，c=12．208（2）A,Z=6；R=0．0240．对KLnN加热，则依次出现脱水、熔化、不可逆相变和NO的分解过程（K2Ce（NO3）5·2H2O除外）K2Ln（NO3）5·2H2O（Ln＝La；Nd；Sm）的NO分三步分解，K2Ln（NO3）5·2H2O（Ln=Ce；Pr）的NO分两步分解·KNO3和Ln（NO3）3·nH2O的混合物在225℃左右生成K2Ln（NO3）5

关键词: 稀土, 硝酸镧钾, 晶体生长, 差热分析

Abstract: Single crystals of KLnN(Ln=La, Ce, Pr, Nd, Sm) can be grown in water solution with pH≈1～2 at about 40℃. Crystals of KLnN
(Ln=La, Ce, Pr, Nd) are orthorhombic with space group Fdd2. KPrN crystal was grwon and its crystal structure was determined for the first time.
The KPrN crystal parameters obtained by the direct method are as follows: a=21.411(3)A, b=11.2210(10)A, c=12.208(2)A, Z=6, R=0.0240. The TG-DTA curves of KLnN(Ln=
La, Ce, Pr, Nd, Sm) demonstrate that the processes of dehydration , melt, irreversible phase transition and decomposition of NO-3 take place in sequence with the temperature increasing(except KCN). There are three steps in the
decomposition of NO-3 in KLnN(Ln=La, Nd, Sm) while two steps in KLnN(Ln=Ce, Pr). K2Ln(NO3)5·2H2O are formed at about 225℃
by the reaction of the starting materials of KNO3 and Ln(NO3)3·nH2O.

Key words: rare earth, potassium lanthanide nitrate hydrate, crystal growth,TG-DTA

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