ON AGGREGATION OF ISOMORPHOUS NITROGEN IMPURITY IN SYNTHETIC DIAMONDS (SYSTEM Fe-Ni-C)

Abstract

The relevance of the research is determined by the importance of nitrogen as the main structural impurity in diamond, the content and form of which affect the properties of diamond, its color characteristics and are used in the analysis of the temperature-time conditions of natural diamond formation. The purpose of this work is to study the features of nitrogen impurity aggregation in synthetic diamonds grown in the Fe-Ni-C system. Object and methods. The studied sample of a synthetic single crystal of diamond was obtained in Fe-Ni-C system by the temperature gradient method at high P, T parameters in the field of stability on a multi-anvil high-pressure apparatus of the «split sphere» type. Determination of nitrogen and the degree of its aggregation were performed using a Bruker Vertex-70 IR Fourier spectrometer with a Hyperion 2000 microscope. When analyzing the spectral data, a specialized program for processing the IR spectra of diamond IR'nDi-Module was used. Results and conclusions. The authors have studied the variation in formation of pair associates of isomorphic nitrogen impurity (degree of aggregation) in the octahedral growth sectors of synthetic diamond obtained with a high nickel content in metal-solvent (Fe20Ni80 at. %). After the gradual achievement of complete aggregation of nitrogen in the outer regions of the crystal, a progressive reverse deaggregation of nitrogen was recorded in its internal, previously formed zones. The established fact cannot be explained within the framework of the known unidirectional kinetics of the nitrogen aggregation and indicates the presence of an additional factor affecting this reaction in diamonds with a high content of an accompanying impurity of nickel. The possibility of nitrogen deaggregation initiated by the redistribution of nitrogen from nitrogen associates (A-defects) to nickel-nitrogen complexes (NE-centers) was suggested for the first time.

Keywords

• diamond
• impurities
• defects
• nitrogen
• aggregation