The Library
XANES study of Ti coordination in heat-treated (TiO2)(x)(SiO2)(1-x) xerogels
Tools
UNSPECIFIED (1999) XANES study of Ti coordination in heat-treated (TiO2)(x)(SiO2)(1-x) xerogels. CHEMISTRY OF MATERIALS, 11 (5). pp. 1253-1258. ISSN 0897-4756.
Research output not available from this repository.
Request-a-Copy directly from author or use local Library Get it For Me service.
Abstract
Accurate measurements of the height and position of the preedge peak in Ti K-edge XANES (X-ray absorption near-edge structure) can distinguish 4-, 5-, and 6-fold coordination of Ti by O (Ti-[4], Ti-[5], and Ti-[6], respectively), and mixtures thereof. This approach has been applied to titania-silica xerogels, (TiO2)(x)(SiO2)(1-x), prepared from Si and Ti alkoxides using a prehydrolysis step and acid catalyst, with 0.18 < x < 0.75. As expected, samples with x = 0.75 contain phase-segregated, amorphous, pre-anatase Ti-[6], which is converted to anatase after heating at 500 degrees C. Samples with x = 0.18 contain a majority of isolated, distorted Ti-[6] before heating, which is converted to Ti-[4] substituted for Si after heating at 750 degrees C. This is the first time that the changes in the coordination of isolated Ti have been unambiguously described. Xerogels with 0.25 < x < 0.35 and heat treatment at 750 degrees C showed concentration limits of Ti-[4] substitution for Si of 10-15mol %. Slightly higher values were obtained for xerogels prepared using acetylacetone, but the main difference was that the latter had a significantly larger content of distorted Ti-[6] before heat treatment. There is no evidence of significant amounts of Ti-[5].
Item Type: | Journal Article | ||||
---|---|---|---|---|---|
Subjects: | Q Science > QD Chemistry T Technology > TA Engineering (General). Civil engineering (General) |
||||
Journal or Publication Title: | CHEMISTRY OF MATERIALS | ||||
Publisher: | AMER CHEMICAL SOC | ||||
ISSN: | 0897-4756 | ||||
Official Date: | May 1999 | ||||
Dates: |
|
||||
Volume: | 11 | ||||
Number: | 5 | ||||
Number of Pages: | 6 | ||||
Page Range: | pp. 1253-1258 | ||||
Publication Status: | Published |
Data sourced from Thomson Reuters' Web of Knowledge
Request changes or add full text files to a record
Repository staff actions (login required)
View Item |