TY - JOUR
T1 - Synthesis and morphological control of large titanosilicate ETS-10 crystals
AU - Ji, Zhaoxia
AU - Warzywoda, Juliusz
AU - Sacco, Albert
N1 - Funding Information:
The authors acknowledge NASA for financial support.
PY - 2008/3/1
Y1 - 2008/3/1
N2 - Hydrothermal synthesis of large titanosilicate ETS-10 crystals was investigated at 473 K by adjusting the Na2O/K2O ratio (x/y) and H2O content (z) of synthesis mixtures with molar composition 5.5SiO2:xNa2O:yK2O:1TiO2:zH2O, where x = 1.66-4.18, y = 0.28-2.80, x + y = 4.46, and z = 300-900. Square truncated bipyramidal crystals with the increasing basal width and decreasing aspect ratio (i.e., decreasing combined height of two pyramids divided by the width of the shared base) were grown upon decreasing x/y in mixtures with z = 300, and by increasing z in mixtures with x/y = 2.0. The largest ETS-10 crystals (average dimensions ∼80 × 80 × 22 μm) were obtained using mixture with x/y = 0.6 and z = 300. These are the largest ETS-10 crystals reported to date. The linear dimensions of the stepped island-like structures that are present on the square crystal faces increased concomitantly with the increasing basal width and decreasing ETS-10 aspect ratio. These results suggest that both the replacement of Na ions by K ions in the synthesis mixture and its dilution with water suppressed three- and two-dimensional nucleation of ETS-10. Also, these results suggest a lower concentration of defects along the ⋯Ti-O-Ti-O-Ti⋯ chains in large crystals.
AB - Hydrothermal synthesis of large titanosilicate ETS-10 crystals was investigated at 473 K by adjusting the Na2O/K2O ratio (x/y) and H2O content (z) of synthesis mixtures with molar composition 5.5SiO2:xNa2O:yK2O:1TiO2:zH2O, where x = 1.66-4.18, y = 0.28-2.80, x + y = 4.46, and z = 300-900. Square truncated bipyramidal crystals with the increasing basal width and decreasing aspect ratio (i.e., decreasing combined height of two pyramids divided by the width of the shared base) were grown upon decreasing x/y in mixtures with z = 300, and by increasing z in mixtures with x/y = 2.0. The largest ETS-10 crystals (average dimensions ∼80 × 80 × 22 μm) were obtained using mixture with x/y = 0.6 and z = 300. These are the largest ETS-10 crystals reported to date. The linear dimensions of the stepped island-like structures that are present on the square crystal faces increased concomitantly with the increasing basal width and decreasing ETS-10 aspect ratio. These results suggest that both the replacement of Na ions by K ions in the synthesis mixture and its dilution with water suppressed three- and two-dimensional nucleation of ETS-10. Also, these results suggest a lower concentration of defects along the ⋯Ti-O-Ti-O-Ti⋯ chains in large crystals.
KW - Crystal morphology
KW - ETS-10
KW - Hydrothermal crystal growth
KW - Large crystals
KW - Titanosilicates
UR - http://www.scopus.com/inward/record.url?scp=37349021762&partnerID=8YFLogxK
U2 - 10.1016/j.micromeso.2007.04.019
DO - 10.1016/j.micromeso.2007.04.019
M3 - Article
AN - SCOPUS:37349021762
SN - 1387-1811
VL - 109
SP - 1
EP - 11
JO - Microporous and Mesoporous Materials
JF - Microporous and Mesoporous Materials
IS - 1-3
ER -