, ▁the ▁Ca CO 3 ▁formed ▁on ▁the ▁surface ▁of ▁a ▁Ca O ▁particle ▁occup ies ▁a ▁larger ▁mol ar ▁volume . ▁As ▁a ▁result , ▁once ▁a ▁layer ▁of ▁carbon ate ▁has ▁formed ▁on ▁the ▁surface ▁( including ▁on ▁the ▁large ▁internal ▁surface ▁of ▁por ous ▁Ca O ), ▁it ▁imp edes ▁further ▁CO 2 ▁capture . ▁This ▁product ▁layer ▁grows ▁over ▁the ▁por es ▁and ▁se als ▁them ▁off , ▁forcing ▁carbon ation ▁to ▁follow ▁a ▁slower , ▁diffusion ▁dependent ▁mechanism . ▁ ▁S inter ing ▁Ca O ▁is ▁also ▁pr one ▁to ▁s inter ing , ▁or ▁change ▁in ▁p ore ▁shape , ▁shr ink age ▁and ▁gra in ▁growth ▁during ▁he ating . ▁I onic ▁comp ounds ▁such ▁as ▁Ca O ▁mostly ▁s inter ▁because ▁of ▁volume ▁diffusion ▁or ▁lattice ▁diffusion ▁mechan ics . ▁As ▁described ▁by ▁s inter ing ▁theory , ▁vac an cies ▁generated ▁by ▁temperature ▁sensitive ▁defect s ▁direct ▁void ▁sites ▁from ▁smaller ▁to ▁larger ▁ones , ▁explaining ▁the ▁observed ▁growth ▁of ▁large ▁por es ▁and ▁the ▁shr ink age ▁of ▁small ▁por es ▁in ▁cy c led ▁lim estone . ▁It ▁was ▁found ▁that ▁s inter ing ▁of ▁Ca O ▁increases ▁at ▁higher ▁temper atures ▁and ▁longer ▁calc ination ▁dur ations , ▁whereas ▁carbon ation ▁time ▁has ▁minimal ▁effect ▁on ▁particle ▁s inter ing . ▁A ▁sharp ▁increase ▁in ▁s inter ing ▁of ▁particles ▁is ▁observed ▁at ▁temper atures ▁above ▁ 1 1 7 3 ▁K , ▁causing ▁a ▁reduction ▁in ▁re active ▁surface ▁area