K. Daimon et al., Formation of MgSO4-Al-2(SO4)(3) solid solution and thermal decomposition into the spinel solid solution, NIP KAG KAI, (6), 2000, pp. 433-435
Solid solution of MgSO4 and Al-2 (SO4)(3) was prepared from mixed aqueous s
olutions by rapid dry using micro-wave heating. The Mg2+ ion is soluble int
o the anhydrous aluminum sulfate crystal lattice over a wide range up to ne
ar the equimolar composition of MgSO4 and Al-2(SO4) (3) The anhydrous alumi
num sulfate solid solution, at first, thermally decompose into the mixture
of eta-Al2O3 and MgSO4. The crystalline spinel phase appears at the second
step of the thermal decomposition. The lattice parameters of the spinel cha
nges linearly with the Mg content ranging from 0.5 to 0.8 at the fraction o
f MgAl2O4/ (MgAl2 O-4 + Al2O3) The produced nonstoichiometric spinel solid
solutions must be metastable because the stable region of the composition o
f the spinel solid solutions is very narrow at the heating temperature empl
oyed to the thermal decomposition.