Estimation of activation parameters for diffusion‐controlled crystallization of barium tungstate from sodium tungstate melts by differential thermal analysis | Zendy

Roy B. N. | Zendy; Roy M. R. | Zendy

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Estimation of activation parameters for diffusion‐controlled crystallization of barium tungstate from sodium tungstate melts by differential thermal analysis

Author(s) -

Roy B. N.,

Roy M. R.

Publication year - 1981

Publication title -

kristall und technik

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.377

H-Index - 64

eISSN - 1521-4079

pISSN - 0023-4753

DOI - 10.1002/crat.19810161108

Subject(s) - crystallization , tungstate , sodium tungstate , activation energy , barium , enthalpy , diffusion , thermodynamics , arrhenius equation , materials science , analytical chemistry (journal) , chemistry , inorganic chemistry , tungsten , chromatography , metallurgy , physics

The proximity ( d 12 ) between a diffusing species and its host crystal necessary for a successful diffusion for diffusion‐controlled crystallization of barium tungstate from sodium tungstate melts in platinum crucibles was estimated. These distances increased with increased cooling rates ( R T ) and crystallization temperatures ( T 0 ). Energy ( E ), enthalpy (Δ H a ), entropy (Δ S a ) and free‐energy (Δ G a ) of activation and the pre‐exponential factor ( k 0 ) were evaluated using an ordinary Arrhenius equation k D1 = k 0 e − E / RT , where k D1 was the diffusion rate‐constant. These parameters were virtually unaffected by the changes in T 0 and R T .

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