彩色金刚石中过渡金属离子的谱学研究

Spectroscopic Studies on Transition Metal Ions in Colored Diamonds

过渡金属镍、钴和铁是高温高压法合成金刚石的常用触媒 ,已有研究表明 :采用镍、钴作触媒所合成的金刚石中存在镍、钴离子 ,部分天然金刚石含有镍离子 ;镍、钴离子以替代方式或间隙形式进入金刚石的晶格 ,并能与杂质氮形成复合体。为了探寻彩色金刚石中过渡金属离子存在的谱学标志 ,确定镍、钴离子在彩色金刚石中的赋存状态 ,文章对 6颗彩色天然与合成金刚石进行了扫描电镜 能谱、显微红外光谱、光致发光谱、电子顺磁共振谱 (EPR)等测试研究。结果表明天然与合成的样品都具有与镍、钴有关的发光中心与EPR结构 :包括西澳的蓝灰色天然金刚石中与镍有关的 884 6nm等发光中心 ,以及天然变色金刚石中与钴有关的发光中心。对各种谱学测试结果的综合分析 ,得出样品中存在镍、钴离子并与杂质氮形成各种Ni N或Co N复合体的结论 ,其中在天然金刚石中发现钴离子在该领域研究中尚属首次。

Transition metals like nickel, cobalt and iron have been often used as solvent catalysts in high pressure high temperature (HPHT) synthesis of diamond, and nickel and cobalt ions have been found in diamond lattice. Available studies indicated that nickel and cobalt ions could enter the lattice as interstitial or substitutional impurities and form complexes with nitrogen. Polarized microscopy, SEM-EDS, EPR, PL and FTIR have been used in this study to investigate six fancy color natural and synthetic diamonds in order to determine the spectroscopic characteristics and the existing forms of transition metal ions in colored diamond lattice. Cobalt-related optical centers were first found in natural chameleon diamonds, and some new nickel and cobalt-related optical and EPR centers have also been detected in these diamond samples.