Thermolysis of Coprecipitated ChromiumZinc Hydroxides

E. A. Telushchenko*, A. M. Kirillov**, M. N. Kopylovich***, and A. K. Baev****

* Minsk Research Institute for Radio Engineering Materials, Minsk, Belarus

** Institute for Powder Metallurgy, Minsk, Belarus

*** Lisbon Technical University, Lisbon, Portugal

**** Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, Russia

Received May 29, 2002

Abstract—Chromium(III)–zinc(II) double hydroxides of various compositions have been prepared by copre-
cipitation from nitrate solutions. The hydroxides and their thermolysis products have been characterized by IR
spectroscopy, differential thermal analysis (DTA), X-ray powder diffraction, and chemical analysis. Phase tran-
sitions in ZnCr₂(OH)₈ · nH₂O (n = 5.5–7.0), Zn₂Cr₂(OH)₁₀ · 7.2H₂O, and Zn₄Cr₂(OH)₁₄ · 7.5H₂O during ther-
molysis have been studied. These hydroxides can be employed for the low-temperature synthesis of ZnCr₂O₄
spinel and its ZnO solid solutions with the spinel phase percentage of 50 and 25 mol %, respectively.

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