The Study Of N-Type Large Diamonds With Sulfur And Boron

High quality type Ⅰb and type Ⅱa large diamond single crystals(diameter about3~4mm)were successfully synthesized by temperature gradient method,under5.6GPa pressure and different temperatures about 1250~1340oC.Large diamonds were successfully synthesized from FeNiMnCo-S-C system at temperatures in the range of 1255-1393oC and pressures of 5.3-5.5 GPa.It was found that the pressure and temperature conditions of large diamond have decreased to some extent with the increase of additive S content and results in left down of the V-shape region.The analysis of X-ray photoelectron spectroscopy(XPS)spectra showed the presence of S in diamonds.When sulfur in the cell of diamond additive was up to4.0%,the resistivity values of the diamond was 9.628×10~5?.cm.It was found that the slight variation of the additive S content had not made obvious change for the color of diamonds synthesized from FeNiCo-C system.The B-S co-doping samples became more transparent and yellow than the samples added alone by S.The analysis of X-ray photoelectron spectroscopy(XPS)spectra and Fourier transform infrared(FTIR)spectroscopy showed the presence of B and S in the obtained diamonds.The highest value of the hall mobility was 628.726 cm~2/vs.And the lowest value of the resistivity was 9.33×10~5?·cm with boron additive of 0.8%and sulfur of 2%doping to diamond which was confirmed as n-type.This work indicated that B-S co-doping to synthesize diamond crystals was a trend to promote the electrical properties of large diamond crystals.n-type large diamonds of type Ib with B-S doping were acquired.But,only single B was assuredly incorporated in the samples which eliminated nitrogen.