Abstract
The development of new strategies for the mass synthesis of SiC nanocrystals with high structure perfection and narrow particle size distribution remains in demand for high-tech applications. In this work, the size-controllable synthesis of the SiC 3C polytype, free of sp2 carbon, with high structure quality nanocrystals, was realized for the first time by the pyrolysis of organosilane C12H36Si6 at 8 GPa and temperatures up to 2000 °C. It is shown that the average particle size can be monotonically changed from ~2 nm to ~500 nm by increasing the synthesis temperature from 800 °C to 1400 °C. At higher temperatures, further enlargement of the crystals is impeded, which is consistent with the recrystallization mechanism driven by a decrease in the surface energy of the particles. The optical properties investigated by IR transmission spectroscopy, Raman scattering, and low-temperature photoluminescence provided information about the concentration and distribution of carriers in nanoparticles, as well as the dominant type of internal point defects. It is shown that changing the growth modes in combination with heat treatment enables control over not only the average crystal size, but also the LO phonon—plasmon coupled modes in the crystals, which is of interest for applications related to IR photonics.
Highlights
Silicon carbide (SiC) is the most widely used non-oxide ceramic, which has applications in many industrial fields, due to its special semiconducting and spin-related properties, high mechanical strength and hardness, high thermal conductivity, resistance to corrosion and thermal shock, etc. [1,2,3,4,5,6,7,8,9,10,11,12]
Our experiments show that with a particle size of more than 200–500 nm, a decrease in the surface-to-volume ratio no longer plays a key role as a driving force in the growth of SiC crystals, and crystal growth slows down
The HTHP synthesis of 3C silicon carbide powders from dodecamethylhexasireplicas, with the participation of longitudinal optical (LO) and LA phonons, with a quasimomentum located at linane was carried out
Summary
Silicon carbide (SiC) is the most widely used non-oxide ceramic, which has applications in many industrial fields, due to its special semiconducting and spin-related properties, high mechanical strength and hardness, high thermal conductivity, resistance to corrosion and thermal shock, etc. [1,2,3,4,5,6,7,8,9,10,11,12]. A number of methods to synthesize nano- and micropowders have already been developed, including growth from hydrogen silicone oil [6], mechanical grinding [11,12], fast carbothermal synthesis [13,14,15], combustion synthesis [16], microwave synthesis [17], pyrolysis of polymers [18], sol-gel processes [19], CVD [20], and laser synthesis [21] All of these processes have their own advantages and disadvantages, associated with the cost of precursors, synthesis conditions, the purity degree of the materials obtained, and others [7]. It is known that HPHT conditions are favorable for producing the SiC 3C polytype in the Si-C system [25,26], its formation stability under pressure in the
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