The influence of crystallization temperature and boron concentration in growth environment on its distribution in growth sectors of type IIb diamond

Structure and superconductivity of isotope-enriched boron-doped diamond

“…The 500 cm −1 band in Raman spectra of BDD was previously assigned to a local vibrational mode of boron pairs [17,21]. Consistent with this assignment, the isotope shift ν( 10 B)/ν( 11 B) ∼ 1.04 of the 500 cm −1 band was observed by changing the boron isotope in BDD prepared with 12 C. The observation of a strong boron isotope shift of the 500 cm…”

“…To extract an isotope effect from this shift of T c , one should take into account the difference in boron doping, which can be calculated from experimentally determined values of the lattice parameters (table 1), and the dependence of T c on the lattice parameter [22]. We estimated T c due to a difference in boron doping as 0.25 K for samples 12 C-10 B and 13 C-10 B and 0.16 K for samples 12 C-11 B and 13 C-11 B. The value of the isotope effect coefficient is β 0 = −dlnT c /dlnM.…”

“…Graphite directly transforms into diamond at pressures of 12-25 GPa and temperatures exceeding 1900 K [10], and one cannot exclude that the synthesis of BDD in the B 4 C-graphite system at 20 GPa [9] begins from the direct conversion of graphite to diamond, which finally leads to a BDD formation scenario very different from that in [1]. In [11,12], the BDD synthesis was carried out using a temperature gradient method at a pressure of 5.5 GPa and temperatures of about 1700-1800 K. A metallic alloy was used as a crystal growth medium for the BDD synthesis. It was reported that the concentration of boron in the crystals did not reach the critical value 7 × 10 20 cm −3 , at which a metal-to-insulator transition takes place in the bulk HPHT single crystals of BDD synthesized with a metal melt [13] and in single-crystalline superconducting films grown by chemical vapor deposition (CVD) [14].…”

“…The observation of an isotope effect would be very important for identification of the vibrational modes as well as for understanding the nature of superconductivity in BDD. Recent work [7] on isotopic substitution of 12 C by 13 C in BDD (C + 7% B) has reported a large carbon-isotope effect on the superconducting transition temperature T c . If this result is correct then it indicates a diamond-related nature of superconductivity in BDD even with boron-rich (95% B + C) inclusions [18].…”

Heavily Boron Doped Diamond Powder: Synthesis and Rietveld Refinement

“…Several methods have been developed for producing boron-doped diamonds (BDD) with low electrical resistance, high mobility of charge carriers, and p-type conductivity. Large single crystals are synthesized at pressures of about 5 GPa [5]. In this case, the boron is in the molten metal through which the graphite recrystallization takes place.…”