|
NAT |
[Ga] Natrolite |
Si(62), Ga(38) |
Contributed by Mario Occelli
Verified by I. Buhl and by R Aiello
Type Material (NaK8R6)[Ga15Si25O80] . wH2O (R = benzyl trimethylammomum (BTMA))
Method M. L Occelli, E. Goldish, H. Eckert [1]
Batch Composition 5.30 Na2O : 2.21 K20 : 2.12 R2O : Ga2O3 : 12.54 SiO2 : 298 H2O : 31.4 CH3OH
Source Materials
deionized water
sodium hydroxide, reagent grade (~97% NaOH)
potassium hydroxide, reagent grade (85% KOH)
gallium oxide (99.99% Ga2O3)
sodium silicate (PQN-brand, 29,9% SiO2, 10.0% Na2O)
benzyl trimethyl ammonium hydroxide (Excel Co., 40% in methanol)
Batch Preparation
(1) [50 g water + 9.92 g sodium hydroxide + 29.0 g potassium hydroxide] mix until dissolved
(2) [(1) + 18.7 g gallium oxide], stir at the boiling point until the solution clears
(3) [(2) +50 g water], mix and cool to ambient temperaturea
(4) [(3) + 167.2 g BTMA. OH solution]
(5) [251.3 g sodium silicate + 274.3 g water] mix for 4 hours
(6) [(5) + (4)], add gallate mixture dropwise to the vigorously stirred, diluted sodium silicate; stir for 10 hours at ambient temperature
Crystallization
Vessel: Teflon-lined, stirred autoclave
Incubation: 10 h at ambient temperature with stirring.
Temperature: 125±2¡C
Time: 7 days
Agitation: 100 rpm
Product Recovery
(1) Filter and wash to pH<10
(2) Dry at 1100C
(3) Yield: near 100% on Ga2O3
Product Characterization
XRD: NAT; no other crystalline phases or amorphous material observed
Elemental Analyses: Ga2O3 : 3.28 SiO2 : 0.11 Na2O : 0.56 K2O : 0.39 (BTMA)2O
Crystal Size and Habit: Anisotropic columns 10-20 um long with an almost square cross
section often bounded at both ends by pyramids. Twinning and intergrowths are common
Click here to view XRD pattern
Reference
[1] M. L Occelli, L Goldish, H. Eckert, in Stud. Surf. Sci. Catal. 84, J. Weitkamp, H. G. Karge, H. Pfeifer, W. Holderich (eds.), 1994, p. 597
Note
a. Diluted gallate solution must be clear.