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If you believe you were blocked by mistake, you can find additional information and instructions in the <a href="https://meta.wikimedia.org/wiki/Special:MyLanguage/No_open_proxies" class="extiw" title="m:Special:MyLanguage/No open proxies">No open proxies</a> global policy. </p> Otherwise, to discuss the block please <a href="https://meta.wikimedia.org/wiki/Steward_requests/Global" class="extiw" title="m:Steward requests/Global">post a request for review on Meta-Wiki</a>. You could also send an email to the <a href="https://meta.wikimedia.org/wiki/Special:MyLanguage/Stewards" class="extiw" title="m:Special:MyLanguage/Stewards">stewards</a> <a href="https://meta.wikimedia.org/wiki/Special:MyLanguage/VRT" class="extiw" title="m:Special:MyLanguage/VRT">VRT</a> queue at <kbd>stewards@wikimedia.org</kbd> including all above details.</div></div><hr /> <p>Cewch weld a chopïo côd y dudalen: </p><textarea readonly="" accesskey="," id="wpTextbox1" cols="80" rows="25" style="" class="mw-editfont-monospace" lang="cy" dir="ltr" name="wpTextbox1">=== Pacio agos === [[File:close packing.svg|thumb|upright=1.3|Dellt pacio agos hecsagonol (hcp) ar y chwith a dellt ciwbig wyneb-ganolog (fcc) ar y dde.]] Gellir deall yr egwyddorion dan sylw trwy ystyried y ffordd fwyaf effeithlon o bacio sfferau maint cyfartal a phentyrru planau atomig wedi eu pacio'n agos mewn tri dimensiwn. Er enghraifft, os yw plân A yn gorwedd o dan plân B, mae dwy ffordd bosibl o osod atom ychwanegol ar ben haen B. Pe bai haen ychwanegol yn cael ei gosod yn union dros plân A, byddai hyn yn arwain at y gyfres ganlynol: :...'''ABABABAB'''... Adnabyddir y trefniant hyn o atomau mewn crisial fel pacio agos hecsagonol '''(hcp - ''hexagonal close packing'')'''. Fodd bynnag, os yw'r tair plân wedi'u gwasgaru mewn perthynas â'i gilydd, ac nad yw'r dilyniant yn cael ei ailadrodd tan i'r bedwaredd haen gael ei gosod yn union dros plân A, yna mae'r dilyniant canlynol yn codi: :...'''ABCABCABC'''... Adnabyddir y math hyn o drefniant strwythurol fel pacio agos ciwbig '''(ccp - ''cubic close packing'')'''. Cell uned trefniant pacio agos ciwbig (ccp) o atomau yw cell uned ciwbig wyneb-ganolog (fcc). Nid yw hyn yn amlwg ar unwaith gan fod yr haenau sydd wedi'u pacio'n agos yn baralel i blanau {111} cell uned ciwbig wyneb-ganolog (fcc). Mae pedwar cyfeiriadedd gwahanol i'r haenau sydd wedi eu pacio'n agos. Gellir cyfrifo'r '''effeithlonrwydd pacio''' trwy rannu cyfanswm cyfaint y sfferau a'u rhannu dros cyfaint y gell, fel y ganlyn: :<math> \frac{4 \times \frac{4}{3} \pi r^3}{16 \sqrt{2} r^3} = \frac{\pi}{3\sqrt{2}} = 0.7405...</math> Effeithlonrwydd pacio o 74% yw'r dwysedd mwyaf posib mewn cell uned wedi ei greu o sfferau o un maint yn unig. Mae'r mwyafrif o ffurfiau crisialog o elfenau metel yn pacio agos hecsagonol (hcp), ciwbig wyneb-ganolog (fcc) neu giwbig corff-ganolog (bcc). [[Rhif cydlyniad]] atomau mewn strwythurau hcp a fcc yw 12, a'i [[ffactor pacio atomig]] (APF - ''atomic packing factor'') yw'r rhif a gyflynwyd uchod, 0.74. Gellir cymharu hyn gyda APF strwythur bcc, sy'n 0.68. </textarea><div class="templatesUsed"></div><p id="mw-returnto">Dychwelyd at <a href="/wiki/Strwythur_crisial" title="Strwythur crisial">Strwythur crisial</a>.</p> <noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Wedi dod o "<a dir="ltr" href="https://cy.wikipedia.org/wiki/Strwythur_crisial">https://cy.wikipedia.org/wiki/Strwythur_crisial</a>"</div></div> <div id="catlinks" class="catlinks catlinks-allhidden" data-mw="interface"></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> </ul> <ul id="footer-places"> <li id="footer-places-privacy"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy">Polisi preifatrwydd</a></li> <li id="footer-places-about"><a href="/wiki/Wicipedia:Yngl%C5%B7n_%C3%A2_Wicipedia">Ynglŷn â Wicipedia</a></li> <li id="footer-places-disclaimers"><a href="/wiki/Wicipedia:Gwadiad_Cyffredinol">Gwadiadau</a></li> <li id="footer-places-wm-codeofconduct"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Universal_Code_of_Conduct">Cod Ymddygiad</a></li> <li id="footer-places-developers"><a href="https://developer.wikimedia.org">Datblygwyr</a></li> <li id="footer-places-statslink"><a href="https://stats.wikimedia.org/#/cy.wikipedia.org">Ystadegau</a></li> <li id="footer-places-cookiestatement"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Cookie_statement">Datganiad cwcis</a></li> <li id="footer-places-mobileview"><a href="//cy.m.wikipedia.org/w/index.php?title=Strwythur_crisial&action=edit&section=13&mobileaction=toggle_view_mobile" class="noprint stopMobileRedirectToggle">Golwg symudol</a></li> </ul> <ul id="footer-icons" class="noprint"> <li id="footer-copyrightico"><a href="https://wikimediafoundation.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><img src="/static/images/footer/wikimedia-button.svg" width="84" height="29" alt="Wikimedia Foundation" loading="lazy"></a></li> <li id="footer-poweredbyico"><a href="https://www.mediawiki.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><img src="/w/resources/assets/poweredby_mediawiki.svg" alt="Powered by MediaWiki" width="88" height="31" loading="lazy"></a></li> </ul> </footer> </div> </div> </div> <div class="vector-settings" id="p-dock-bottom"> <ul></ul> </div><script>(RLQ=window.RLQ||[]).push(function(){mw.config.set({"wgHostname":"mw-web.codfw.main-6df7948d6c-dzg2x","wgBackendResponseTime":155,"wgPageParseReport":{"limitreport":{"cputime":"0.006","walltime":"0.007","ppvisitednodes":{"value":18,"limit":1000000},"postexpandincludesize":{"value":705,"limit":2097152},"templateargumentsize":{"value":0,"limit":2097152},"expansiondepth":{"value":2,"limit":100},"expensivefunctioncount":{"value":0,"limit":500},"unstrip-depth":{"value":0,"limit":20},"unstrip-size":{"value":0,"limit":5000000},"entityaccesscount":{"value":0,"limit":400},"timingprofile":["100.00% 0.000 1 -total"]},"cachereport":{"origin":"mw-web.codfw.main-6df7948d6c-dzg2x","timestamp":"20241127213931","ttl":2592000,"transientcontent":false}}});});</script> </body> </html>