2020. gada novembr\u012b tika public\u0113ts raksts, kur\u0101 tika zi\u0146ots par sint\u0113zi par a<\/s> nanokrist\u0101lisko dimantu un lonsdale\u012btu istabas temperat\u016br\u0101, ko l\u012bdz \u0161im uzskat\u012bja par neiesp\u0113jamu. <\/p>\n\n\n\n
Sintezi veica zem 80 GPa spiediena no nekrist\u0101liska oglek\u013ca parauga prekursora. Tas bija iesp\u0113jams tikai ar augstu spiedienu un b\u012bdes spriegumu, kas ir \"svar\u012bgi, lai veicin\u0101tu f\u0101\u017eu veido\u0161anos, jo var pal\u012bdz\u0113t p\u0101rvar\u0113t kin\u0113tiskos \u0161\u0137\u0113r\u0161\u013cus\", rakst\u0101 teikts.<\/a> <\/p>\n\n\n\n P\u0113t\u012bjuma rezult\u0101ti balst\u0101s uz \u013coti izplat\u012btu elektronu mikroskopijas metodi, ko pla\u0161i izmanto kristalogr\u0101fij\u0101, kas ir eksperiment\u0101l\u0101 joma, kur\u0101 p\u0113ta atomu izvietojumu krist\u0101lisk\u0101s cietviel\u0101s, \u0161aj\u0101 rakst\u0101 apl\u016bkotaj\u0101 gad\u012bjum\u0101 - dimant\u0101 un lonsdale\u012bt\u0101.<\/p>\n\n\n\n Dimants, mazais (vai ar\u012b ne) un d\u0101rgais sp\u012bd\u012bg\u0101s klints gabals, ir ne tikai d\u0101rga rotaslieta, bet ar\u012b \u0101rk\u0101rt\u012bgi svar\u012bgs materi\u0101ls, pateicoties t\u0101 \u012bpa\u0161\u012bb\u0101m, kas \u013cauj to izmantot gan parast\u0101s, gan ekstr\u0113m\u0101s vid\u0113s. <\/p>\n\n\n\n Da\u017eas noder\u012bgas \u012bpa\u0161\u012bbas ir \u0101rk\u0101rt\u012bgi augsta ciet\u012bba, augsta siltumvad\u012btsp\u0113ja, un to var izmantot ar\u012b biomedic\u012bn\u0101. <\/p>\n\n\n\n Lonsdale\u012bts ir dimantam l\u012bdz\u012bgs materi\u0101ls ar neliel\u0101m at\u0161\u0137ir\u012bb\u0101m krist\u0101liskaj\u0101 strukt\u016br\u0101, sal\u012bdzinot ar dimantu, bet dimantam piem\u012bt kubisk\u0101 krist\u0101lisk\u0101 strukt\u016bra<\/strong> ar tetraedriski saist\u012btu oglekli, lonsdeil\u012btam ir heksagon\u0101l\u0101 krist\u0101lisk\u0101 strukt\u016bra<\/strong>, kas ir ret\u0101k sastopams p\u0101rk\u0101rtojuma veids.<\/p>\n\n\n\n Liel\u0101k\u0101 da\u013ca p\u0113t\u012bjumu par dimanta sint\u0113zi liecina, ka ir nepiecie\u0161amas divas ierosmes formas, lai p\u0101rvar\u0113tu materi\u0101lu f\u0101\u017eu izmai\u0146u augsto kin\u0113tisko barjeru. <\/p>\n\n\n\n Dimanta un lonsdale\u012bta sint\u0113zei laboratorij\u0101 parasti izmanto augstu spiedienu un paaugstin\u0101tu temperat\u016bru.<\/p>\n\n\n\n M\u016bsdien\u0101s zin\u0101tniekiem ir diagramma, kas par\u0101da k\u0101da materi\u0101la fizik\u0101lo st\u0101vokli atkar\u012bb\u0101 no temperat\u016bras un spiediena, ko sauc par. f\u0101\u017eu diagramma. \u013boti slavens un <\/strong>noder\u012bgs pal\u012bgl\u012bdzeklis zin\u0101tniekiem, lai uzzin\u0101tu, k\u0101da temperat\u016bra un spiediens ir nepiecie\u0161ami, lai sasniegtu konkr\u0113tu st\u0101vokli, piem\u0113ram, cietu, \u0161\u0137idru vai g\u0101zveida. Oglek\u013ca atomi, graf\u012bts un dimants ir divi ciet\u0101 st\u0101vokl\u012b eso\u0161i piem\u0113ri.<\/p>\n\n\n\n Ja paskat\u0101s uz oglek\u013ca diagramma<\/a>, dimanta st\u0101vokli var\u0113tu sasniegt istabas temperat\u016br\u0101 virs 2GPa spiediena, ta\u010du realit\u0101t\u0113 ir j\u0101\u0146em v\u0113r\u0101 citi faktori, kas var rad\u012bt milz\u012bgas at\u0161\u0137ir\u012bbas gala rezult\u0101t\u0101. Viens no \u0161iem faktoriem, kas min\u0113ts rakst\u0101, ir b\u012bdes spriegums<\/strong>.<\/p>\n\n\n\n \u0160\u013cau\u0161anas spriegumu paz\u012bst k\u0101 procesu, kur\u0101 paral\u0113li sl\u0101\u0146i sl\u012bd viens caur otru. \u013boti vienk\u0101r\u0161s piem\u0113rs tam ir, kad j\u016bs saliekat rokas kop\u0101 un s\u0101kat sl\u012bd\u0113t viena uz otras - piem\u0113ram, kad j\u016btaties auksti un v\u0113laties sasild\u012bt rokas - \u0161\u012b kust\u012bba rada b\u012bdes spriegumu rok\u0101s vai izmantotaj\u0101 materi\u0101l\u0101. <\/p>\n\n\n\n B\u012bdes spriegums var veicin\u0101t materi\u0101lu f\u0101\u017eu mai\u0146u. Ne\u0146emot v\u0113r\u0101 temperat\u016bru, sl\u012bdes spriegums, izr\u0101d\u0101s, ir svar\u012bgs komponents tam, k\u0101 \"dimants var veidoties daudz pla\u0161\u0101k\u0101 vid\u0113, gan sauszemes, gan \u0101rpuszemes, nek\u0101 uzskat\u012bts iepriek\u0161\", ta\u010du, lai apstiprin\u0101tu sl\u012bdes sprieguma ietekmi, ir nepiecie\u0161ami v\u0113l daudzi p\u0113t\u012bjumi. Ar\u012b lonsdale\u012bta veido\u0161an\u0101s ir saist\u012bta ar b\u012bdes spriegumu. <\/p>\n\n\n\n M\u0113\u0123inot ieg\u016bt dimantu un lonsdale\u012btu istabas temperat\u016br\u0101, zin\u0101tnieki saspieda stiklveida oglek\u013ca paraugus 80 \u00d7 10 % apm\u0113r\u0101.9<\/sup>Pa - tas ir liels spiediens, daudz, daudz liel\u0101ks nek\u0101 tas, ko j\u016bs izjut\u0101t, k\u0101rtojot k\u0101rt\u0113jo p\u0101rbaud\u012bjumu koled\u017e\u0101. <\/p>\n\n\n\n \u0160is skaitlis ir l\u012bdzv\u0113rt\u012bgs gandr\u012bz 800 t\u016bksto\u0161u atmosf\u0113ras spiedienam - m\u0113s dz\u012bvojam tikai vien\u0101 atmosf\u0113r\u0101.<\/p>\n\n\n\n Zin\u0101tnieki analiz\u0113ja paraugu rezult\u0101tus, izmantojot tr\u012bs da\u017e\u0101dus elektronu mikroskopijas veidus. Ramana spektroskopija, rentgenstaru difrakcija un TEM (transmisijas elektronu mikroskopija). Apl\u016bkosim katru no tiem.<\/p>\n\n\n\n Port\u0101ls Ramana spektroskopija<\/strong> ir metode, kas \u013cauj noteikt konkr\u0113ta materi\u0101la struktur\u0101lo pirkstu nospiedumu, izmantojot molekulu vibr\u0101cijas re\u017e\u012bmi<\/a>. <\/p>\n\n\n\n Parauga materi\u0101ls mijiedarbojas ar monohromatisku gaismu - parasti l\u0101zeru - absorb\u0113jot un emit\u0113jot fotonus neelast\u012bg\u0101s izkliedes veid\u0101, citiem v\u0101rdiem sakot, parauga molekul\u0101r\u0101 vibr\u0101cija absorb\u0113 vair\u0101kus fotonus, absorb\u0113tais daudzums at\u0161\u0137iras no emit\u0113t\u0101. <\/p>\n\n\n\n \u0160\u012b at\u0161\u0137ir\u012bba tiek konstat\u0113ta, un galarezult\u0101ts \u013cauj zin\u0101tniekiem ieg\u016bt inform\u0101ciju par parauga strukt\u016bru.<\/p>\n\n\n\n Rentgena staru difrakcija<\/strong> metode ietver elektronu stara izmanto\u0161anu monohromatisk\u0101s gaismas viet\u0101. \u0145emot v\u0113r\u0101 atomu izvietojuma mode\u013cus krist\u0101liskaj\u0101 strukt\u016br\u0101, kad rentgena staru k\u016blis sasniedz paraugu, tas izklied\u0113jas daudzos da\u017e\u0101dos le\u0146\u0137os un virzienos. <\/p>\n\n\n\n Zin\u0101tnieki var izm\u0113r\u012bt \u0161os le\u0146\u0137us un izklied\u0113t\u0101 staru k\u016b\u013ca intensit\u0101ti, p\u0101rveidojot datus tr\u012bsdimensiju att\u0113l\u0101 ar atomu atra\u0161an\u0101s viet\u0101m krist\u0101l\u0101.<\/p>\n\n\n\n Port\u0101ls TEM, transmisijas elektronu mikroskopija<\/strong> ir mikroskopijas metode, kur\u0101 gaismas, k\u0101 ar\u012b rentgena staru difrakcijas viet\u0101 izmanto elektronu staru k\u016bli. <\/p>\n\n\n\n Paraugs tiek pak\u013cauts staru k\u016blim, kas caur to iet cauri un ar fluorescences detektora pal\u012bdz\u012bbu rada att\u0113lu. <\/p>\n\n\n\n \u0160ai metodei ir nepiecie\u0161ama parauga sagatavo\u0161ana uz re\u017e\u0123a, un t\u0101 tiek apz\u012bm\u0113ta k\u0101 izvair\u012bga metode, jo anal\u012bzes laik\u0101 paraugs tiek izn\u012bcin\u0101ts.<\/p>\n\n\n\n P\u0113c m\u0113\u0123in\u0101juma ieg\u016bt dimantu p\u0113tnieki ar Ramana metodi atkl\u0101ja, ka paraugi sast\u0101v tikai no graf\u012bta materi\u0101la. <\/p>\n\n\n\n Tom\u0113r rentgenstaru difrakcijas mode\u013ci uzr\u0101d\u012bja at\u0161\u0137ir\u012bgus rezult\u0101tus, pier\u0101dot lonsdale\u012bta (12%), dimanta (3%) un graf\u012bta (85%) kl\u0101tb\u016btni. <\/p>\n\n\n\n \u0160ie at\u0161\u0137ir\u012bgie rezult\u0101ti ir izskaidrojami ar katras metodes at\u0161\u0137ir\u012bb\u0101m. Ramana metode sp\u0113j analiz\u0113t tikai materi\u0101lu virsmu, savuk\u0101rt rentgena staru difrakcija var analiz\u0113t visu parauga biezumu.<\/p>\n\n\n\n Kopum\u0101 \u0161is rezult\u0101ts pier\u0101da, ka t\u0101du cietu materi\u0101lu k\u0101 dimants veido\u0161anos nosaka ne tikai spiediens un temperat\u016bra. <\/p>\n\n\n\n Materi\u0101lu veido\u0161anos var izrais\u012bt ar\u012b citi faktori, piem\u0113ram, b\u012bdes spriegums vai faktori, kurus zin\u0101tne v\u0113l pat nezina. <\/p>\n\n\n\n Iesp\u0113jams, n\u0101kotn\u0113, kad \u0161\u012b kompresijas tehnika b\u016bs nostiprin\u0101jusies lab\u0101k, padarot dimanta ra\u017eo\u0161anu l\u0113t\u0101ku, zin\u0101tne var\u0113s piln\u012bb\u0101 izmantot \u0161\u012b materi\u0101la priek\u0161roc\u012bbas. <\/p>\n\n\n\n _____<\/p>\n\n\n\n Vai j\u016bs jau esat Mind the Graph <\/a>lietot\u0101js? Ja t\u0101 nav, varat s\u0101kt tie\u0161i tagad<\/a>! Varat ar\u012b noklik\u0161\u0137in\u0101t uz \u0161eit<\/a> lai apskat\u012btu m\u016bsu zin\u0101tnisko ilustr\u0101ciju galeriju, jums nav j\u0101s\u0101k projekts no nulles! \n\n<\/p>","protected":false},"excerpt":{"rendered":" 2020. gada novembr\u012b tika public\u0113ts raksts, kur\u0101 zi\u0146ots par nanokrist\u0101liska dimanta un lonsdale\u012bta sint\u0113zi istabas temperat\u016br\u0101, ko l\u012bdz \u0161im uzskat\u012bja par neiesp\u0113jamu. Sintezi veica zem 80 GPa spiediena no nekrist\u0101liska oglek\u013ca parauga prekursora. Tas bija iesp\u0113jams tikai ar augstu spiedienu un b\u012bdes spriegumu, kas bija \"svar\u012bgi [...].<\/p>","protected":false},"author":4,"featured_media":12058,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[959,28],"tags":[814,554,775],"yoast_head":"\n