Infrared absorption studies of the annealing of irradiated diamonds

Nanometers-Thick Ferromagnetic Surface Produced by Laser Cutting of Diamond

In this work, we demonstrate that cutting diamond crystals with a laser (532 nm wavelength, 0.5 mJ energy, 200 ns pulse duration at 15 kHz) produced a ≲20 nm thick surface layer with magnetic order at room temperature. We measured the magnetic moment of five natural and six CVD diamond crystals of different sizes, nitrogen contents and surface orientations with a SQUID magnetometer. A robust ferromagnetic response at 300 K was observed only for crystals that were cut with the laser along the (100) surface orientation. The magnetic signals were much weaker for the (110) and negligible for the (111) orientations. We attribute the magnetic order to the disordered graphite layer produced by the laser at the diamond surface. The ferromagnetic signal vanished after chemical etching or after moderate temperature annealing. The obtained results indicate that laser treatment of diamond may pave the way to create ferromagnetic spots at its surface.

The effect of pressure on synthetic diamond crystals at high temperatures and pressures in an Fe/Ni catalyst system

Pressure is a necessary condition for the growth of natural diamond.

Growth and characterization of diamond single crystals grown in the Fe–S–C system by the temperature gradient method

Diagram of the apparatus for the HPHT diamond synthesis: (a) alloy hammer + pyrophyllite assembly block; (b) sample assembly.

Probing the Nanostructure of Neutron-Irradiated Diamond Using Raman Spectroscopy

Disordering of crystal lattice induced by irradiation with fast neutrons and other high-energy particles is used for the deep modification of electrical and optical properties of diamonds via significant nanoscale restructuring and defects engineering. Raman spectroscopy was employed to investigate the nature of radiation damage below the critical graphitization level created when chemical vapor deposition and natural diamonds are irradiated by fast neutrons with fluencies from 1 × 10¹⁸ to 3 × 10²⁰ cm⁻² and annealed at the 100–1700 °C range. The significant changes in the diamond Raman spectra versus the neutron-irradiated conditions are associated with the formation of intrinsic irradiation-induced defects that do not completely destroy the crystalline feature but decrease the phonon coherence length as the neutron dose increases. It was shown that the Raman spectrum of radiation-damaged diamonds is determined by the phonon confinement effect and that the boson peak is present in the Raman spectra up to annealing at 800–1000 °C. Three groups of defect-induced bands (first group = 260, 495, and 730 cm⁻¹; second group = 230, 500, 530, 685, and 760 cm^–1; and third group = 335, 1390, 1415, and 1740 cm⁻¹) were observed in Raman spectra of fast-neutron-irradiated diamonds.

Synthesis and characterization of diamonds using C3H5N3O as an organic additive under high pressure and high temperature

In the NiMnCo–C system, diamond single crystals have been successfully synthesized by adding C₃H₅N₃O as an organic additive under 5.5–6.2 GPa and 1280–1320 °C.

Raman spectroscopic features of the neutral vacancy in diamond from ab initio quantum-mechanical calculations

Ab initio calculations of the Raman spectrum of the neutral vacancy in diamond reproduce observed spectral features of irradiated diamond up to the first-order peak.