Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group
  • Applied Spectroscopy
  • Vol. 66,
  • Issue 6,
  • pp. 665-672
  • (2012)

Monitoring of a Calcination Reaction of High Reflective Green-Black (HRGB) Pigments by Using Near-Infrared Electronic Spectroscopy: Calcination Temperature-Dependent Crystal Structural Changes of Their Components and Calibration of the Extent of the Reaction

Not Accessible

Your library or personal account may give you access


This paper demonstrates the potential of near-infrared (NIR) electronic spectroscopy in nondestructive monitoring of a chemical reaction of inorganic functional material. For this purpose NIR spectra in the 12 000-4000 cm−1 region were measured for high reflective green-black (HRGB) pigments (Co0.5Mg0.5Fe0.5Al1.5O4) calcined at 1000, 1100, and 1200 °C and pigments with the same components as HRGB but calcined at different temperatures (500-900 °C) (hereafter, called “Pigments A”) . NIR spectra of their components such as Co3O4, MgO, Fe2O3, and Al2O3 were also measured. The NIR spectra of Pigments A show two major broad bands. One arises from a 4A24T1 (Th) d-d transition of Co(II) in the 9000-6000 cm−1 region. The other band in the 12 000-9000 cm−1 region is assigned to a foot of the charge-transfer (CT) band of Fe2O3. The Co(II) band contains three component bands that are characteristic of a spinel structure. A shoulder arising from (A1-xBx)Th(AxB2-x)OhO4 (A≡Co, Mg, B≡Fe, Al; inverse spinel structure) emerges near 5900 cm−1 in the spectra of Pigments A calcined in the temperature range of 700-900 °C, indicating that the Pigments A calcined in this temperature range assume an inverse spinel structure. When the calcination temperature is above 1000 °C, the final product, HRGB, is produced. This is confirmed from the fact that HRGB shows peaks characteristic of a spinel structure that have different wavenumbers from those of the corresponding peaks of Pigments A. Wide-angle X-ray diffraction (WAXD) patterns were also measured for HRGB, Pigments A, and their components. Based on the NIR and WAXD data we investigated calcination-temperature-dependent crystal structural changes of the components. We also developed partial least squares (PLS) calibration models for the 9000-6000 cm−1 region of the NIR spectra of HRGB and Pigments A. The score plot of latent variable (LV) 2 of the calibration model for calcination temperature demonstrates clearly the existence of an intermediate of the calcination reaction, which may be (A1-xBx)Th(AxB2-x)OhO4 (A≡Co, Mg, B≡Fe, Al).

PDF Article

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
Login to access Optica Member Subscription

Select as filters

Select Topics Cancel
© Copyright 2022 | Optica Publishing Group. All Rights Reserved