Experimentaldetails
Adipic acidwiththeformula(CH2)4(COOH)2, whichisapowder
at roomtemperature,wasusedinthisworkasaprecursorforthe
direct conversionintoacarbonsamplecontainingnano-diamond
grains.Thesamplewascompressedusingacustom-built5000-ton
multi-anvil pressatatemperatureof1235 °C andpressureof
14GPafor1h.Theadipicacidpowderwasplacedinsideathin
graphitesleeveandweldedintoa2mmdiametergoldcapsule.A
0.025 mmthickpieceofmolybdenumfoilwasplacedatthebot-
tomofthecapsuleto fix theoxygenfugacity.Thecapsulewas
carefullycompressedtoproduceacylinder3.5mmlongand
placed insideacylindricalsleevemadeofhexagonalboronnitride
(h-BN). ThecapsuleandsleevewasplacedatthecenterofaLa-
CrO3 (Sr-doped)cylindricalheater.Spacebelowthecapsulewas
filled withanMgOcylinder,whilefromaboveaW3%Re-W25%Re
(type d)thermocoupleinsidea4-borealuminatubewasinserted
throughafurtherMgOsleeve.Thefurnacewassurroundedbya
ZrO2 insulator.Theentireassemblywasplacedintoa6.8mm
diameter holeboredintoan18mmedgelengthMgO(Cr2O3-