Al2O3:Cr3+ microfibers by hydrothermal route: Luminescence properties

Liu, Dianguang; Zhu, Zhiliang; Liu, Hui; Zhang, Zhengyang; Zhang, Yanbin; Li, Gege

doi:10.1016/j.materresbull.2012.05.026

Cited by 11 publications

(2 citation statements)

References 15 publications

(15 reference statements)

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“…Many methods are used to prepare Cr-doped Al 2 O 3 , e.g., chemical vapor deposition [15,16], the combustion method [17,18,19,20,21], conventional solid–state method [22,23,24,25], sol–gel method [26,27,28], hydrothermal method [29,30], pulsed electric-current sintering process [31,32], and microwave-solvothermal method [33,34]. Recently, the solid-state method has been widely used to synthesize colored Cr-doped ceramic pigments [23,24,25].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Thermochromic Properties of Cr-Doped Al2O3 for a Reversible Thermochromic Sensor

2017

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An inorganic thermochromic material based on Cr-doped Al2O3 is synthesized using a solid-state method. The crystal structure, chemical composition, and morphology of the synthesized material are analyzed using X-ray diffraction, scanning electron microscopy coupled with an energy-dispersive X-ray spectrometer, and Fourier transform infrared (FT-IR) spectroscopy. The color performances of the synthesized material are analyzed using a UV-VIS spectrometer. Finally, the thermochromism exhibited by the powdered samples at high temperatures is investigated. The material exhibits exceptional thermochromic property, transitioning from pink to gray or green in a temperature range of 25–600 °C. The change in color is reversible and is dependent on the surrounding temperature and chromium concentration; however, it is independent of the exposure time. This novel property of Cr-doped Al2O3 can be potentially employed in reversible thermochromic sensors that could be used not only for warning users of damage due to overheating when the environmental temperature exceeds certain limits, but also for detecting and monitoring the temperature of various devices, such as aeronautical engine components, hotplates, and furnaces.

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Section: Introductionmentioning

confidence: 99%

Synthesis and Thermochromic Properties of Cr-Doped Al2O3 for a Reversible Thermochromic Sensor

2017

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“…Ruby is one of the most precious gemstones on the market; it is a variety of corundum, and its structural formula is Al 2 O 3 , in which a small amount of Al 3+ is replaced by Cr 3+ ions [1]. Most natural rubies show uneven color saturation, sometimes with bands of blue color.…”

Section: Introductionmentioning

confidence: 99%

Chemical and Spectral Variations between Untreated and Heat-Treated Rubies from Mozambique and Madagascar

Sun

Qin³

2022

Minerals

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The chemical composition and spectra of untreated and heat-treated rubies from Mozambique and Madagascar were analyzed by an electron probe microscopy analysis, laser ablation inductively coupled plasma quadrupole mass spectrometry, Fourier transform infrared spectroscopy, Raman spectroscopy and UV-visible spectroscopy. Due to the different content of Fe and different inclusions, rubies from Madagascar belong to alkaline basalt deposit, while rubies from Mozambique belong to amphibole metamorphic rock. The ruby samples were heated to 900 °C to change their color. As Fe and Ti ions can be transferred into different valences and diffused into the interior of rubies, Cr ions in cracks or cleavages entered the crystal lattice during heat treatment and the content of Fe and Ti decreased, while the content of Cr increased in heat-treated rubies. After heating, blue-purple decreased and the red hue increased, while the blue color band disappeared and yellow appeared in the cracks of the samples because of the chemical changes. Compared with untreated rubies, the infrared absorption peaks of 2123 cm−1 and 1990 cm−1 related to inclusions disappeared, and the existence of 3236 cm−1 and 3186 cm−1 absorption peaks was a typical characteristic of heat-treated ruby, which was produced by changes in its inclusion. In addition, due to the weakened charge transfer of Fe2+ and Ti4+ and the increasing reaction of Fe2+ → Fe3+ along with the heat treatment, the UV-visible absorption peak at 400 nm shifted to purple.

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