钙铁硅铁磁体微晶玻璃晶化与核化的研究

STUDY ON NUCLEATION AND CRYSTALLIZATION OF CALCIUM IRON SILICATE FERROMAGNETIC GLASS-CERAMICS

铁磁体微晶玻璃是用于温热治疗肿瘤的一种热种子材料 .使用XRD ,DTA ,SEM -EPMA ,M ssbauer和VSM对添加了少量改善生物活性的P2 O5 和B2 O3或Na2 O的钙铁硅微晶玻璃在还原气氛下热处理的核化与晶化特性进行了研究 .钙铁硅玻璃在还原气氛下热处理后其主要晶相是磁铁矿和硅灰石及少量赤铁矿 .随着玻璃化学组成和热处理条件的不同 ,微晶玻璃中也会出现少量钙铁辉石、钙铁橄榄石等其它晶相 .由于玻璃中存在很大的分相倾向 ,钙铁硅微晶玻璃中磁铁矿的核化是在成形冷却过程中完成的 ,核化速度很快 .硅灰石的核化速度较慢 ,在重新加热进行热处理的过程中完成 .添加少量P2 O5 和B2 O3的钙铁硅玻璃的成核机理以整体成核为主 ,而添加少量P2 O5 和Na2 O的钙铁硅玻璃以表面成核为主 .经过 10 0 0℃ ,2h热处理的钙铁硅微晶玻璃中椭球形磁铁矿晶粒大小约 2 5 0nm ,硅灰石晶粒大小约 15 0nm .

Ferromagnetic glass-ceramics can be expected to be useful as thermaosseeds for hyperthermia of tumor. Nucleation and crystallization of calcium iron silicate glass-ceramics containing minor P2O5 and B2O3 or Na2O to improve their bioactivity were investigated by XRD, DTA, SEM-EPMA, Mossbauer spectrum and VSM after heat-treatment in reduction atmosphere. The main crystals in the calcium iron silicate glass-ceramics heat-treated are magnetite, wollastonite and minor hematite. Hedenbergite, kirschsteinite and other crystals may also be found in the glass-ceramics, depending on the composition of glass and the heat-treatment schedule. The nucleation of magnetite is rapid during forming. Wollastonite, whose nucleation rate is slower than magnetite, nucleated in the process of heat-treatment. The nucleation mechanism of the glass-ceramics containing minor P2O5 and Na2O is surface nucleation. The particle sizes of ellipsoidal magnetite and wollastonite in the glass-ceramic formed after heat-treatment at 1000°C for 2 h are about 250 nm and 150 nm respectively. The glass-ceramics has magnetic properties and heat-generating power necessary for hyperthermia.