Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (12): 2422-2426.doi: 10.3866/PKU.WHXB20091215

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In situ Microcalorimetry Insight into the Growth of CaMoO4 Microcrystallites

MI Yan, HUANG Zai-Yin, JIANG Jun-Ying, LI Yan-Fen   

  1. College of Chemistry&Ecological Engineering, Guangxi University for Nationalities, Nanning 530006, P. R. China
  • Received:2009-08-10 Revised:2009-10-04 Published:2009-11-27
  • Contact: HUANG Zai-Yin E-mail:hzy210@yahoo.cn

Abstract:

In situ calorimetric studies of CaMoO4 microcrystallite fabrication were performed in an alkalescent aqueous solution. We first presented an oscillatory microcalorimetric heat flow curve pattern which traced the energy evolution of the CaMoO4 microcrystallite growth process. A characteristic endothermic peak for the initial reaction and double relatively weak and discontiguous exothermic peaks for the subsequent crystal growth were observed. We briefly discussed the morphology evolution and the thermokinetics information of the growth process of CaMoO4 microcrystallites on the basis of the oriented attachment mechanism. The rate constants of the reaction and nucleation, crystal crystallization, and microcrystalline secondary growth were found to be 1.54×10-4, 1.09×10-4, and 0.71×10-4 s-1, respectively. As the crystals aggregated and repelled each other, the reaction slowed leading to a relatively flatter second exothermic curve.

Key words: Microcalorimetry, Thermokinetics, CaMoO4, Microcrystallite, Characteristic heat flow curve, Oriented attachment mechanism

MSC2000: 

  • O642