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We investigated the correlation between microstructures and optical properties of boron ion implanted microcrystalline diamond (B-MCD) thin films annealed at different temperatures. Ellipsometry characterization of B-MCD films was performed in the wavelength range of 380–1000 nm and the disperse parameters of the films such as single oscillator energy and dispersive energy were uniquely determined by using a Gaussian model. The results show that the refractive index increases from 2.18 to 2.21 to 2.28–2.29 with annealing temperature increasing from 700 to 800 °C and then it slightly decreases to 2.25–2.28 with annealing temperature further increasing to 900 °C, implying that the annealing temperature has a significant impact on the optical properties of B-MCD films. Raman spectra reveal that the full width at half maximum of diamond peak significantly decreases after 800 °C annealing, indicating a better quality of diamond crystalline. X-ray photoelectron spectroscopy results show that this sample contains higher sp3 carbon content, lower sp2 and C–O contents on the film surface after 800 °C annealing, implying that fewer defects exist. The results are of great significance for the preparation of excellent boron ion implanted microcrystalline diamond for waveguide based Mach-Zehnder Interferometer liquid sensing.

Due to the fatigue and continuous energy input during high-speed dynamic friction polishing (DFP), the diamond crystal beneath the polished surface (roughness 50 nm) and even preferential crystal cleavage with the non-diamond phase (distributing at the position in micrometers range).

Microorganisms promoted corrosion has caused significant loss to marine engineering and the antibacterial coatings have served as a solution that has gained attention. In this study, the chemical vapour deposition technique has been employed to grow three different types of diamond coatings, namely, ultrananocrystalline diamond (UNCD), nanocrystalline diamond (NCD), and microcrystalline diamond (MCD) coatings. The evolution of associated surface morphology and the surface functional groups of the grown coatings have demonstrated antibacterial activity in seawater environments. It is found that different ratio of sp3/sp2 carbon bonds on the diamond coatings influences their surface property (hydrophobic/hydrophilic), which changes the anti-adhesion behaviour of diamond coatings against bacteria. This plays a critical role in determining the antibacterial property of the developed coatings. The results show that the diamond coatings arising from the deposition process kill the bacteria via a combination of the mechanical effects and the functional groups on the surface of UNCD, NCD, and MCD coatings, respectively. These antibacterial coatings are effective to both Gram-negative bacteria (E. coli) and Gram-positive bacteria (B. subtilis) for 1–6 h of incubation time. When the contact duration is prolonged to 6 h or over, the MCD coatings begin to reduce the bacteria colonies drastically and enhance the bacteriostatic rate for both E. coli and B. subtilis.

Antibiotic resistance in bacteria is a current threat causing an increasing number of infections of difficult clinical management. While the overuse and misuse of antibiotics are investigated to reduce them, the need for alternatives to approaches is rising. Carbon-based materials shown recent moderate to high antibacterial properties and diamond, thanks to its superior mechanical, tribological, electrical, chemical and biological quality is a choice material to investigate for safe antibacterial films, coatings and particles. Here, the antibacterial properties of diamond films, nanodiamonds, DLC films and a comprehensive list of the composites developed from them are discussed along with a summary of the bacterial strains used and the most efficient composition and/or concentration discovered. In a later stage, the mechanisms of action and the parameters that are believed to influence them are discussed and finally, an overview of the biomedical and food industry applications is given.

The burgeoning multi-field applications of diamond concurrently bring up a foremost consideration associated with nitrogen. Ubiquitous nitrogen in both natural and artificial diamond in most cases as disruptive impurity is undesirable for diamond material properties, eg deterioration in electrical performance. However, the feat of this most common element-nitrogen, can change diamond growth evolution, endow diamond fancy colors and even give quantum technology a solid boost. This perspective reviews the understanding and progress of nitrogen in diamond including natural occurring gemstones and their synthetic counterparts formed by high temperature high pressure (HPHT) and chemical vapor deposition (CVD) methods. The review paper covers a variety of topics ranging from the basis of physical state of nitrogen and its related defects as well as the resulting effects in diamond (including nitrogen termination on diamond surface), to precise control of nitrogen incorporation associated with selective post-treatments and finally to the practical utilization. Among the multitudinous potential nitrogen related centers, the nitrogen-vacancy (NV) defects in diamond have attracted particular interest and are still ceaselessly drawing extensive attentions for quantum frontiers advance.

CuAlO2 has been examined as a potential luminescent material by substituting Eu for Al cations in the delafossite structure. CuAlO2:Eu3+ nanofibers have been prepared via electrospinning for the ease of mitigating synthesis requirements and for future optoelectronics and emerging applications. Single-phase CuAlO2 fibers could be obtained at a temperature of 1100 °C in air. The Eu was successfully doped in the delafossite structure and two strong emission bands at ~405 and 610 nm were observed in the photoluminescence spectra. These bands are due to the intrinsic near-band-edge transition of CuAlO2 and the f-f transition of the Eu3+ activator, respectively. Further electrical characterization indicated that these fibers exhibit semiconducting behavior and the introduction of Eu could act as band-edge modifiers, thus changing the thermal activation energies. In light of this study, CuAlO2:Eu3+ fibers with both strong photoluminescence and p-type conductivity could be produced by tailoring the rare earth doping concentrations.