Thermal Decomposition Processes of Lanthanum Sulfate and Lanthanum Carbonate

DOI Web Site 1 Citations

Bibliographic Information

Other Title
  • 硫酸ランタンおよび炭酸ランタンの熱分解過程について
  • リュウサン ランタン オヨビ タンサン ランタン ノ ネツ ブンカイ カテイ

Search this article

Abstract

As a part of the study of sintering behaviors of oxides, the thermal decomposition processes of La2(SO4)39H2O and La2(CO3)3 were investigated by using T. G. A. and X-ray diffraction. From the results obtained, the detailed mechanisms of their decomposition were inferred.<br>(1) The thermo-gravimetric curves of the specimens were obtained in air, N2, and CO2 gas. The thermal decomposition curves showed three stages for La2(SO4)39H2O and two stages for La2(CO3)3. The chemical reaction of each stage was determined as follows.<br>La2(SO4)3·9H2O:<br>La2(SO4)3·9H2O→La2(SO4)3+9H2O (the first stage)<br>La2(SO4)3→La2O2(SO4)+2SO2+O2 (the second stage)<br>La2O2(SO4)→La2O3+SO3 (the third stage)<br>La2(CO3)3:<br>La(CO3)3→La2O3CO2+2CO2 (the first stage)<br>La2O3CO2→La2O3+CO2 (the second stage)<br>(2) These reactions were interpreted to be the first order reaction in all atmospheres. The rate constants for three decomposition stages in air of La2(SO4)39H2O were represented by<br>k1=105.4exp(-13000/RT) (the first stage)<br>k2=1012exp(-65000/RT) (the second stage)<br>k3=1017exp(-134000/RT) (the third stage)<br>and those for the two decomposition stages in air of La2(CO3)3 were<br>k1=1013exp(-50000/RT) (the first stage)<br>k2=1012exp(-67000/RT) (the second stage)<br>(3) The lattice constants of La2O3 obtained were a=3.89Å and c=6.08Å. Lanthanum sulfate and carbonate decomposed to La2O3 at about 1500°C and 1000°C, respectively.

Journal

Citations (1)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top