The Effect of Calcination Temperature on the Structure and Performance of Nanocrystalline Mayenite Powders.

Katarzyna Berent,Radosław Lach,Sebastian Komarek,Waldemar Pyda

doi:10.3390/ma12213476

Katarzyna Berent, Radosław Lach + Show 2 more

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https://doi.org/10.3390/ma12213476

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Journal: Materials	Publication Date: Oct 24, 2019
Citations: 22	License type: CC BY 4.0

Affiliation: AGH University of Krakow

Abstract

The effect of calcination temperature on the structural properties and phase formation of synthesized CaO-Al2O3 nanopowder was investigated and discussed. The calcination products were identified by differential thermal analysis (DTA) and the crystalline phase formation was analyzed by X-ray diffraction (XRD). The obtained results showed that the crystallization started at 460 °C. Finally, the microstructures of the nanoparticles were observed by scanning (SEM) and transmission electron (TEM) microscopes. The investigation showed that an increase in the calcination temperature led to the appreciable increase in the crystallite size and the crystallinity of the final product. The obtained data confirmed that the prepared materials were mayenite with different surface area in the range of 71.18 m2/g to 10.34 m2/g after annealing in the temperature range of 470 °C to 960 °C.

Highlights

The calcium aluminates, CaO-Al2 O3 (C-A) system is a promising group of materials due to superior refractory properties
The main components of this mixture, which was dried to constant weight at 100 ◦ C, were nano-boehmite and calcium hydroxide, but the hydrogranet phase (Ca3 Al2 (OH)12, C3AH6) in the amount of 23.3 wt %, which is already formed at 45 ◦ C according to [30], was found
Calcium carbonate was introduced into the mixture together with calcium hydroxide in which it was present in an amount of 3.99%, as revealed by TG/differential thermal analysis (DTA) analysis of this reagent

Summary

Introduction

The calcium aluminates, CaO-Al2 O3 (C-A) system is a promising group of materials due to superior refractory properties. Mayenite (12CaO·7Al2 O3 labelled as C12A7) is an auspicious functional material for usage in various engineering applications, such as catalysis [1,2,3,4], in particular, used in the synthesis of ammonia [5,6], batteries [7], white light-emitting diodes (W-LEDs) [8], electronic [9] and optoelectronic devices [10], which results from the discovery of oxygen mobility [11]. The substitution for the free oxygen ions O2− by F− , Cl− and OH− induces C12A7 into an electride in which electrons behave as anions [14]

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