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RE2O3-NH4HF2系合成稀土氟化物的反應規律

Principles of reactions in the synthesis of rare earth fluorides in RE2O3-NH4HF2 systems

  • 摘要: 在RE2O3-NH4HF2系中,以稀土氧化物和氟化氫銨為原料,分別在常壓和真空狀態下,研究了該體系的各步反應,提出了新的合成REF3反應規律.粉狀La2O3,Gd2O3與NH4HF2在低溫下開始反應,產物為RENH4F4(RE=La,Gd),NH4F,NH3和H2O,高溫下RENH4F4分解為REF3和NH4F,伴有NH4F的揮發和分解;整個過程包括合成、分解和脫銨三個步驟;真空可以降低反應的起止溫度.制備稀土氟化物應采用"常壓低溫合成-真空高溫分解、脫銨"工藝.

     

    Abstract: Rare earth fluorides were synthesized with RE2O3 and NH4HF2 under atmospheric pressure and vacuum in RE2O3-NH4HF2 systems, the reactions in the systems were studied, and a new mechanism for the synthesis of REF3 was proposed. Powder La2O3, Gd2O3 started to react with NH4HF2 at low temperature, and the products were RENH4F4(RE=La, Gd), NH4F, NH3 and H2O. RENH4F4 was decomposed to REF3 and NH4F at high temperature, accompanied with the volatilization and decomposition of NH4F. The whole process could be divided into three steps of synthesis, decomposition and deammoniation. The initial and final temperatures of the reactions were reduced under vacuum. The combination process of synthesis under atmospheric pressure at low temperature and decomposition and deammoniation under vacuum at high temperature should be applied to the preparation of rare earth fluorides.

     

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