Synthesis and in situ transformation of PST-1: a potassium gallosilicate natrolite with a high Ga content.
The synthetic details of a novel potassium gallosilicate natrolite with Si/Ga = 1.28, denoted PST-1, are described. The presence of K(+) and Ga with well-defined levels of concentration in the synthesis mixture is essential for directing its crystallisation. PST-1 transforms rapidly into TNU-6 under hydrothermal conditions, behaviour that contrasts sharply with its very high thermal and hydrothermal stability, which is unusual for a material of such a high Ga content. These stability issues are discussed and rationalized based on chemical composition, likely violations of Loewenstein's rule and the temperature of dehydration of as-made K-PST-1. The crystal structure of TNU-6 has been resolved through the combined use of synchrotron X-ray and electron diffraction data; it has the BaFeGaO(4) structure type with an additional radical 3a x radical 3a "GeAlO(4)" superstructure that arises from tilting of some of the tetrahedral units in all of the 6-rings.
Shin
Jiho
J
School of Environmental Science and Engineering and Department of Chemical Engineering, POSTECH, Pohang, 790-784, Korea.
Kim
Seok Han
SH
Camblor
Miguel A
MA
Warrender
Stewart J
SJ
Miller
Stuart R
SR
Zhou
Wuzong
W
Wright
Paul A
PA
Hong
Suk Bong
SB
D005857:Germanium / Q000737:chemistry*; D010316:Particle Size; D011188:Potassium / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D013696:Temperature; D014961:X-Ray Diffraction; D017641:Zeolites / Q000737:chemistry*
D017640:Silicates; D005857:Germanium; D017641:Zeolites; D011188:Potassium