| 摘要 |
1,075,177. Synthetic garnet. WESTERN ELECTRIC CO. Inc. June 30, 1964 [July 10, 1963], No. 26927/64. Heading H1H. Bismuth substituted garnets of formula Bi x M 3-x [Fe y Mt<SP>1</SP> 2-y ](Fe z M<SP>11</SP> 3-z )O 12 where M represents cations of, say, the rare earths, alkaline earth metals, manganese in dodecahedral garnet sites, M<SP>1</SP> and M<SP>11</SP> represent cations of e.g. titanium, zirconium, hafnium, magnesium, zinc, gallium, indium, silicon, germanium, tin chromium, manganese, cobalt, nickel, scandium, aluminium in octahedral and tetrahedral sites respective, x is 0.05 to 1À5, y is 1 to 2, z is 0À5 to 3.0 and at least 2À5-y, are synthesized by mixing stoichiometric proportions of the oxides, or oxide equivalents, of each cation and firing the mixture at 900‹ C. to 1400‹ C. to form a single phase garnet. The starting material may be precalcined at 500‹ C. increasing to 900‹ C., e.g. for I hour, and successively ground and fired over a variety of temperatures and times with, say, increase or decrease in temperature, cooling, regrinding and mixing between each temperature variation. A bismuth excess of up to 10% may be added to the starting material to compensate for vaporization losses, or extra bismuth added at a stage in the firing schedule, or the container may be sealed off during firing or an internally introduced bismuth-containing atmophere used. |
