Abstract
For the guidance of the study on the celite part, I have studied in order to reexamine the studies of both home and abroad on the brownmillerite.
For this purpose, by microscopic and X ray methods I have investigated on the each fired sample of the mixtures, whose mloar compositions are 3CaO:Al2O3:Fe2O3, 4CaO: Al2O3:Fe2O3, 5CaO:Al2O3:Fe2O3, 6CaO:Al2O3:2Fe2O3 and 6CaO:2Al2O3:Fe2O3, which had been studied by many investigators in the study of the celite part.
The results of my study on them are as follows:
(1) Each fired sample consists of 1-3 different crystals, and the principal mineral which occupies whole or most part of each sample is a ferric oxide series compound (perhaps, a solid solution), that has deep red and brown colour, fibrous structure, strong double refraction and high refractive index.
(2) In the crystal consisting of the ferric oxide series compound, that is the principal mineral of each sample, the zonal structure is found by the microscopic observation. This is a crystalline phase known in a solid solution.
(3) By the X ray analysis, each X ray powder photograph of these samples gives a diffraction pattern of 2CaO⋅Fe2O3 type, and the principal minerals seem to have the internal structure of strictly the same type, but each is only different in the interplanar spacing of lattice. Such a phenomenon is seen in a solid solution.
(4) From my experimentation, in the fired sample of 4CaO:Al2O3:Fe2O3, its lattice spacing is the same with the spacing of so-called brownmillerite that has been already reported by many investigators.
(5) The lattice spacing of each sample is reduced in the order of 2CaO⋅Fe2O3, 6CaO:Al2O3:2Fe2O3, 3CaO:Al2O3:Fe2O3, 5CaO:Al2O3:Fe2O3, 4CaO:Al2O3:Fe2O3, and 6CaO:2Al2O3:Fe2O3.
Thus, each principal mineral existing in each of the above five fired samples seem to lie in a solid solution series.
In my experimentation, it is considered that the principal mineral existing in the fired sample of 6CaO:2Al2O3:Fe2O3 is a solid solution that has the greatest miscibility.
But if we think of the existence of a compound in this series insistently, from the above result of the X ray analysis it is only right and proper to rather think of the existence of such a ferric oxide series compound of high lime-alumina as existing in the fired sample of the mix, 6CaO:2Al2O3:Fe2O3, than of the brownmillerite.
Thereupon, the brownmillerite (4CaO⋅Al2O3⋅Fe2O3) should be considered to occupy a region in a solid solution series between 2CaO⋅Fe2O3 and a compound of higher lime-alumina than 4CaO⋅Al2O3⋅Fe2O3.
Thus, the existence of the brownmillerite is still open to doubts.
(6) In the principal mineral of the ferric oxide series that exist in all fired samples of higher lime mixtures (5CaO: Al2O3:Fe2O3, 6CaO:Al2O3:Fe2O3, and so on) than 4CaO:Al2O3:Fe2O3, the more the content of lime in the mixtures increases, the more the content of lime-alumina in the principal mineral existing in its fired sample decreases.
(7) In 5CaO:Al2O3:Fe2O3, if investigated
