Spectroscopic Investigation of Properties of Blue Sapphire Samples Depending on Heating Conditions

The 3309, 3232, and 3185 cm –1 are a series of peaks defined as the 3309 cm –1 -series peaks of the functional group absorptions in the mid-infrared region of gem corundum samples, in particular, the blue sapphires. In this study, the 3309 cm –1 -series peaks were attributed to –Ti–OH stretching. Ho...

Full description

Saved in:
Bibliographic Details
Published in:Journal of applied spectroscopy 2019-11, Vol.86 (5), p.810-816
Main Authors: Phlayrahan, A., Monarumit, N., Lhuaamporn, T., Satitkune, S., Wathanakul, P.
Format: Article
Language:English
Subjects:
Absorption spectra
Aluminum oxide
Analysis
Analytical Chemistry
Atmospheric heating
Atomic/Molecular Structure and Spectra
Corundum
Functional groups
Gems
Investigations
Iron
Oxidation
Physics
Physics and Astronomy
Precious stones
Sapphire
Titanium
Titanium dioxide
Valence
X ray absorption
X-ray fluorescence
X-ray spectroscopy
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The 3309, 3232, and 3185 cm –1 are a series of peaks defined as the 3309 cm –1 -series peaks of the functional group absorptions in the mid-infrared region of gem corundum samples, in particular, the blue sapphires. In this study, the 3309 cm –1 -series peaks were attributed to –Ti–OH stretching. However, the application of revealing these series peaks is still limited because the mechanism of those peaks during the heating process has yet to be clarified. This study showed that the characteristics of the peaks depend strongly on the TiO 2 content in the sapphire samples. Energy dispersive X-ray fluorescence (EDXRF) spectrometry indicated that the samples with Ti content >0.02 wt.% usually show the 3309 cm –1 -series peaks with strong intensity. In addition, the X-ray absorption spectra (XAS) revealed that the oxidation state of Fe is Fe 3+ while Ti is Ti 4+ for every heating temperature. The UV-Vis-NIR optical absorption showed that the alteration of the bands at 580 and 710 nm, defined as the Fe 3+ /Ti 4+ pair, was related directly to the atmospheric heating conditions. In contrast, the intensity of the 3309 cm –1 -series peaks gradually decreased with increase in heating temperatures in any given atmosphere. This is a result of the mechanism of the bonding between Ti and/or Fe atoms and –OH in blue sapphire structures caused by the heating.
ISSN:0021-9037
1573-8647
DOI:10.1007/s10812-019-00898-y