Substitution of Ba for Ca in the Structure of CaAl₁₂O₁₉

Abstract

The effect of Ba2+ on the crystallization thickness of calcium hexaaluminate (CA6) along the c axis was studied. The results show that after introduction of Ba2+, the CA6 flake crystals fired at 1600°C become thicker obviously. The structure refinement shows that the structure formula of the doped CA6 is (Ca0.973Ba0.027)O·6Al2O3, indicating Ba2+ has entered the lattices of CA6 and substituted Ca2+ in the mirror layers. The introduction of Ba2+ results in more defects VAl in spinel block layers in CA6, making ions easier to diffuse along c axis and fastening the growing of CA6 crystals along c axis. Thus, the introduction of Ba2+ is feasible and advantageous to increase the crystallization thickness of CA6 along c axis.

Synthesis of CA6/AlON Composites with Enhanced Slag Resistance

“…In view of the slag layer as shown in Fig. 10(b is consistent with the results reported by Chen et al [1] As for the corrosion zone, the thickness is approximate 345 µm. The whole phase composition in this zone is similar, i.e.…”

“…Calcium hexaaluminate (CaAl 12 O 19 , usually denoted as CA 6 ) is of great interest as high temperature ceramics bene ting from the combination of excellent properties including high melting point, good alkaline resistance, high stability in a reducing atmosphere, and low thermal conductivity, and so on [1][2][3][4]. However, CA 6 possesses a magnetoplumbite structure and belongs to hexagonal crystal system (space group P63/mmc) [5][6][7].…”

Effect of CaO on Phase Composition and Properties of Aluminates for Barium Tungsten Cathode

“…When the molar amount of CaO was 0.8, the structure of Ba 3 CaAl 2 O 7 phase was unstable due to the many Ca 2+ vacancies, and the second phase of Ba 5 CaAl 4 O 12 was formed. When the molar amount of CaO increased from 2 to 2.2, the excess CaO had no effect on the phase composition of aluminates, and the diffraction peak continued to shift to a higher angle, which suggested that Ca 2+ might be filling in the lattice of the Ba 3 CaAl 2 O 7 phase in the form of interstitial ions, so that the interplanar spacing decreased [ 24 ]. The reason for the broadening of the diffraction peak might be that the increase of CaO made the crystallization degree of 6BaO·xCaO·2Al 2 O 3 aluminates lower, and the grain size decreased.…”

Preparation, growth mechanism and slag resistance behavior of ternary Ca2Mg2Al28O46 (C2M2A14)

“…CaAl 12 O 19 (CA 6 ), a binary compound in the CaO‐Al 2 O 3 system with a high melting point of 1875°C and theoretical density of 3.79 g/cm 3 , exhibits such merits as good chemical stability in reducing atmosphere and alkaline conditions as well as low wettability to molten metal and slag, which results in its wide application in steel, petrochemical and aluminum industries . Therefore, CA 6 has attracted intensive attention and become an important research direction in refractories industry in recent years .…”