Characteristics of diamond crystals from FeNiCo-C system with Ge doping under high pressure and high temperature

Abstract

Various optical color centers in natural and synthetic diamond have attractive great attention of researched; to further investigate the effects of additive on diamond properties is of practical significance. In this work, diamond crystallization was investigated by temperature gradient growth method with Ge additive at a set pressure of 6.5 GPa and synthesis temperature ranging from 1290 to 1310 °C. Scanning electron microscope (SEM), and spectral characterization including Fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL) spectra were used to investigate the surface growth mechanism of diamond. It was noticed that the visible inclusions gradually reduced in the as-grown diamond, accompanying with the increase of Ge additive in the synthesis cavity. The (111) surface of the synthesized diamond followed the layer growth pattern from the SEM results. According to the measured FTIR results, the nitrogen impurity concentration values of the synthesized diamond crystals decreased from 500 to 90 ppm, confirming that Ge showed its own ability to remove nitrogen impurity in the growth stage of diamond. Additionally, the nickel-related and nitrogen-related optical color centers of the obtained diamond were characterized by PL spectra. Characteristic peaks due to nickel-related optical color centers located at 515 or 535 nm, and Characteristic peaks attributing to nitrogen-related optical color centers located at 575 or 637 nm. We believe that the research is of great significance for the application of diamond in optical and quantum information science fields.