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 40Fe(2)O(3), 29CaO, 31SiO(2), 3P(2)O(5) (weight ratio) was heat-treated at a rate of 5 degreesC.min(-1) in 90CO(2)+10H(2) atmosphere. Magnetite started to precipitate at 650 degreesC, increased its crystallite size and volume fraction with increasing heat treatment temperature to reach 150 nm and 36 mass%, respectively at 1150 degreesC. The saturation magnetization of heat-treated specimens increased with increasing heat treatment temperature to reach 32.4 emu.g(-1) after treatment at 1150 degreesC. The coercive force of the heat-treated specimen increased with increasing heat treatment temperature to reach 430 Oe at 950 degreesC, and then decreased to reach 150 Oe at 1150 degreesC. The specimen heat-treated at 1150 degreesC showed the maximum heat generation, 7.5 W.g(-1), under 300 Oe and 100 kHz.