2D Similarity of NaCl(111) and Urea(111) Epitaxy Growth of Crystal twhen epitaxy growth, both gas and liquid, the match of lattice parameter should be considered 2图包是出盐 For example, in preparation of conducting thin og 099 crystallized from the supersatura =3.82A),the substrate can be the single crystal slice: SrTiO(100).a=3.91A aortio of unres aue te growth slowe than that of NaCl (100) dn hydrothermal deposition of TiO, thin film aThe 2D similarity of crystal Si(100), the lattice parameter of TiO structure cause such phenomena. b=10917A,d12=2a(a=543A,2a=1 0, so grow TiOg thin film with high 112 orientation. Carbon Allotropes Graphite Carbon shows both Layer and Cage Networks Graphite&s 2各 Diamond Sphalerite (ZnS)vs Diamond Structure Diamond hybrid C Ta group strongest/hardest material 深x known shows us the 4-fold coordination in bot High thermal conductivity (unlike ceramics) structures Transparent in the visible and infrared with high index of refraction Semiconduct doped to make devices Metastable (transforms to see the“ diamond carbon when heated)2 2D Similarity of NaCl(111) and Urea(111) (3 Cl- constitute equilateral triangle; 3 urea molecules constitute triangle. Compare the two triangles,the lateral length of the latter is twice that of the former. (octahedral NaCl crystal can be crystallized from the supersaturated solution of NaCl with urea. Absorption of Urea (111) on the NaCl (111) planes cause the growth rate of NaCl (111) rather slower than that of NaCl (100). (The 2D similarity of crystal structure cause such phenomena. Epitaxy Growth of Crystal When epitaxy growth, both gas and liquid, the match of lattice parameter should be considered. For example, in preparation of YBa2Cu3O7-d superconducting thin film, (a=3.88 Å, b=3.82 Å)，the substrate can be the single crystal slice: SrTiO3 (100), a=3.91 Å 。 In hydrothermal deposition of TiO2 thin film on Si(100), the lattice parameter of TiO2 : (a=5.354 Å, b=10.917 Å), d112=2asi,(a=5.43 Å, 2a=10.86 Å), so grow TiO2 thin film with high 112 orientation. Carbon shows both Layer and Cage Networks Carbon Allotropes Diamond Graphite Diamond sp3 hybrid C Td group One of the strongest/hardest material known High thermal conductivity (unlike ceramics) Transparent in the visible and infrared, with high index of refraction. Semiconductor (can be doped to make electronic devices) Metastable (transforms to carbon when heated) Sphalerite (ZnS) vs Diamond Structure Ball and stick shows us the 4-fold coordination in both structures Looking at tetrahedra in the structure helps us see the “diamond shape