TY - JOUR

T1 - Crystallization of diamond from melts of europium salts

AU - Borzdov, Yuri M.

AU - Khokhryakov, Alexander F.

AU - Kupriyanov, Igor N.

AU - Nechaev, Denis V.

AU - Palyanov, Yuri N.

PY - 2020/5/7

Y1 - 2020/5/7

N2 - Diamond crystallization in melts of europium salts (Eu2 (C2 O4)3·10H2 O, Eu2 (CO3)3·3H2 O, EuCl3, EuF3, EuF2) at 7.8 GPa and in a temperature range of 1800–2000◦ C was studied for the first time. Diamond growth on seed crystals was realized at a temperature of 2000◦ C. Spontaneous diamond nucleation at these parameters was observed only in an Eu oxalate melt. The maximum growth rate in the europium oxalate melt was 22.5 µm/h on the {100} faces and 12.5 µm/h on the {111} faces. The diamond formation intensity in the tested systems was found to decrease in the following sequence: Eu2 (C2 O4)3·10H2 O > Eu2 (CO3)3·3H2 O > EuF3 > EuF2 = EuCl3 . Diamond crystallization occurred in the region of stable octahedral growth in melts of Eu3+ salts and in the region of cubo-octahedral growth in an EuF2 melt. The microrelief of faces was characterized by specific features, depending on the system composition and diamond growth rate. In parallel with diamond growth, the formation of metastable graphite in the form of independent crystals and inclusions in diamond was observed. From the spectroscopic characterization, it was found that diamonds synthesized from Eu oxalate contain relatively high concentrations of nitrogen (about 1000−1200 ppm) and show weak PL features due to inclusions of Eu-containing species.

AB - Diamond crystallization in melts of europium salts (Eu2 (C2 O4)3·10H2 O, Eu2 (CO3)3·3H2 O, EuCl3, EuF3, EuF2) at 7.8 GPa and in a temperature range of 1800–2000◦ C was studied for the first time. Diamond growth on seed crystals was realized at a temperature of 2000◦ C. Spontaneous diamond nucleation at these parameters was observed only in an Eu oxalate melt. The maximum growth rate in the europium oxalate melt was 22.5 µm/h on the {100} faces and 12.5 µm/h on the {111} faces. The diamond formation intensity in the tested systems was found to decrease in the following sequence: Eu2 (C2 O4)3·10H2 O > Eu2 (CO3)3·3H2 O > EuF3 > EuF2 = EuCl3 . Diamond crystallization occurred in the region of stable octahedral growth in melts of Eu3+ salts and in the region of cubo-octahedral growth in an EuF2 melt. The microrelief of faces was characterized by specific features, depending on the system composition and diamond growth rate. In parallel with diamond growth, the formation of metastable graphite in the form of independent crystals and inclusions in diamond was observed. From the spectroscopic characterization, it was found that diamonds synthesized from Eu oxalate contain relatively high concentrations of nitrogen (about 1000−1200 ppm) and show weak PL features due to inclusions of Eu-containing species.

KW - Characterization

KW - Crystal morphology

KW - Crystallization

KW - Defects

KW - Diamond

KW - High temperature

KW - High-pressure

KW - Rare-earth ions

KW - rare-earth ions

KW - HIGH-PRESSURE

KW - CARBON

KW - CENTERS

KW - high temperature

KW - MANTLE

KW - crystal morphology

KW - diamond

KW - FLUID

KW - high-pressure

KW - defects

KW - crystallization

KW - characterization

UR - http://www.scopus.com/inward/record.url?scp=85085069986&partnerID=8YFLogxK

U2 - 10.3390/cryst10050376

DO - 10.3390/cryst10050376

M3 - Article

AN - SCOPUS:85085069986

VL - 10

JO - Crystals

JF - Crystals

SN - 2073-4352

IS - 5

M1 - 376

ER -