Recrystallization of barium ferrite under high pressure oxygen

Abstract Barium ferrite (BaFe 12 O 19 ) and a substituted composition (BaZnTiMnFe 9 O 19 ) were each melted at approximately 1500 °C without flux in platinum crucibles under high oxygen pressures. Total melting could only be achieved by minimizing the conductive heat-loss by the use of a platinum cover incorporating a hole large enough for visibility and Czochralski crystal withdrawal. When BaFe 12 O 19 (“M” phase) was recrystallized by slow cooling under 20 atm of oxygen, BeFe 18 O 27 (“W” phase) was a major constituent: at 50 atm, only the ferric iron containing “M” phase was detected by X-ray analysis. The substituted barium ferrite melted under 50 atm showed an “M”, “W”, spinel and α-Fe 2 O 3 phase.