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for dehydroxylation or decarbonation. They can most likely be attributed to decomposition of the metal oxide into a spinel phase resulting in the loss of oxygen. The following mechanism can be proposed for the thermal decomposition of the synthetic

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Journal of Thermal Analysis and Calorimetry
Authors: Hou-yin Zhao, Yan Cao, Zhi-zhong Kang, Yau-bang Wang, and Wei-ping Pan

showed the new formation of CuAl 2 O 4 spinel during the redox cycles. Figure 3 shows that the fresh oxygen carrier was composed of CuO and Al 2 O 3 . After the first reduction, it was reduced to Cu while after first oxidation, it was oxidized to CuAl

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°C in the DTA curve at heating rate 10 °C min −1 . Fourth endothermic peak between 415 and 670 °C with the maximum rate at 525 °C corresponds to the dehydroxylation process to metakaolinite [ 52 , 53 ]. In addition, the formation of a spinel phase

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) At 970 °C (sharp DTA exothermic peak), rebuilding of the metakaolinite internal structure takes place (Al, Si), spinel like phase in amorphous silica (SiO 2 ) matrix is formed. Structure of the spinel is rebuilt and next quantities SiO 2 expelled

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after 1 h of mechanical activation is the same as that after 2 h of mechanical activation. Chakraborty [ 27 ] stated that the exothermic peak at ∼980 °C was related to the crystallization of the Al–Si spinel phase, weakly crystalline mullite

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thermoluminescence properties. Cinibulk [ 8 ] assigned in his work the structure of magnetoplumbite for CA 6 , which consists of conduction layers and spinel blocks. Calcium hexaaluminate has shown a promise as an interface phase in fiber-reinforced ceramic

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among researchers. So understandably, development of synthetic techniques to prepare nanomaterials has taken center stage. Among the various magnetic materials, the spinel ferrite is a widely studied class due to its remarkable magnetic and electric

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form from the interaction of amorphous SiO 2 either with alumina of the kaolinite or the spinel phase from metakaolinite at 1150 °C. Temuujin et al. [ 7 ] investigated the phase evolution behavior of kaolinite—gibbsite mixtures by mechanochemical

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through short-range thermal phases [ 14 ]. The intermediary phases in this process have been described as defect Al-spinel or γ-alumina phase and poorly crystallized cubic mullite. Al-spinel phase is detected at about 900 °C [ 14 ]. The formation of well

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tetrahedral sites, avoiding the γ-Al 2 O 3 to α-Al 2 O 3 transition and stabilizing CoAl 2 O 4 spinel phase at lower temperatures. In both samples, a peak at about 35° (•) was also observed and is related to KCl phase from the coconut water. Besides

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