B_4C作碳源高压合成金刚石的EPR谱特性

THE CHARACTER OF THE EPR SPECTRA FOR THE DIAMOND SYNTHESISED USING B 4C AS THE CARBON SOURCE UNDER HIGH-PRESSURE

与传统用石墨作碳源不同，首次用Ｂ４Ｃ作碳源，在高温高压与过渡金属合金触媒作用下，合成出高含硼黑色金刚石。这种金刚石的ＥＰＲ谱不再具有由孤立替位氮引起的三共振峰，而是一条线宽为７×１０－４特斯拉、ｇ＝２．００２３、浓度约为２×１０１８自旋数／厘米３的罗伦兹型单峰。分析表明：这可能是金刚石中硼杂质引起的受主中心，抵消了氮原子的未偶电子顺磁性后，所产生的共振现象。由于Ｂ４Ｃ分离出碳原子少，金刚石生长速度较慢，金刚石中铁磁杂质含量低，因此，它们引起的共振现象不明显。

For the first time, the black diamonds with high rich boron were synthesised using B 4C as a carbon source under high-temperature and high-pressure, and under the catalytic effect of transitional metal alloys, which is different from the traditional method that graphite is used as a carbon source. The EPR spectra of this kind of diamond are not any longer three resonant peaks caused by isolated replaceable nitrogen, but a single resonant peak of Lorentz type with the line-width of 7×10 -4 T, g=2.0023 and the concentration of 2×10 18 spin numbers/cm 3. The analysis shows that the resonant phenomenon may occur when the acceptor centers of the boron atoms with high concentration in the diamonds had offset the electron paramagnetism of the nitric atoms with unpaired electrons. Because there are few carbon atoms from the B 4C, diamonds are formed with a low speed and iron-magnetic impurities contents of the black diamonds are very thin, so the resonant phenomenon is obviousless.