Preparation of Magnetite-Containing Glass-Ceramics in Controlled Atmosphere for Hyperthermia of Cancer

Ferrimagnetic glass-ceramics are useful as thermoseeds for hyperthermia of cancers, especially those located at deep parts of the body, since cancers are locally heated by hysteresis loss of the magnetite. When, after implantation at around the cancer, they are placed under an alternating magnetic field. In the present study, a glass of composition 40Fe2O3, 29CaO, 31SiO2, 3P2O5 (weight ratio) was heat-treated at a rate of 5°C·min-1 in 90CO2+10H2 atmosphere. Magnetite started to precipitate at 650°C, increased its crystallite size and volume fraction with increasing heat treatment temperature to reach 150nm and 36mass%, respectively at 1150°C. The saturation magnetization of heat-treated specimens increased with increasing heat treatment temperature to reach 32.4emu·g-1 after treatment at 1150°C. The coercive force of the heat-treated specimen increased with increasing heat treatment temperature to reach 430Oe at 950°C, and then decreased to reach 150Oe at 1150°C. The specimen heat-treated at 1150°C showed the maximum heat generation, 7.5W·g-1, under 300Oe and 100kHz.