绿黄色磷灰石热处理紫外可见光谱研究

doi:10.3964/j.issn.1000-0593(2020)01-0147-05

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Abstract Recently, a special kind of apatites in the gem trade has been popular for its charming color which is similar to “Paraiba” bluish-green tourmaline. In order to prove whether the color of this apatite is processed, this paper put apatite samples with different colors respectively in the air atmosphere heated from 400 to 800 ℃. The experimental results show that, after heated at 650 ℃, yellowish-green samples can be changed into bluish-green. With temperature adding up to 800 ℃, all samples’ color were vanished. According to X-ray diffraction data, there is no phase transformation during the treatment. Subsequently, some yellowish-green samples are treated with different experimental parameters. Results show that the color change of samples is very similar in both air atmosphere and reducing atmosphere, which indicates that the color change is not related to the variation of the valence states. The UV-Vis spectra (200～800 nm) obtained at room temperature show that there are three apparent regions: a strong absorption between 300 and 450 nm, a transmittance from 450 to 550 nm, and a wide absorption band between 620 and 720 nm. Besides, there are some tiny peaks at 515, 528, 578, 739 and 747 nm. With the increase of temperature, the absorption coefficient of the samples is decreased significantly, causing color light. The absorption edge shifts to short wavelength, which reduces the absorption in the blue region and makes sample bluer. When the temperature reaches 400 ℃, the maximum absorption position in 620～720 nm displays a blue-shift resulting in less yellow tone. In the following, the absorption in 620～720 nm disappear and the color of sample vanish for the absorption coefficient keeping at a low level when the temperature adds up to 800 ℃. However, those tiny peaks still exist. Therefore, the color change in the heat treatment process is mainly related to the absorption edge and 620～720 nm absorption band.

Key words：Apatite; Thermal treatment; UV-Vis spectral; Absorption edge

Received: 2018-11-19 Accepted: 2019-03-12

ZTFLH:

P575.4

Corresponding Authors: Andy Hsitien Shen E-mail: ahshen@foxmail.com

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2020)01-0147-05 OR https://www.gpxygpfx.com/EN/Y2020/V40/I01/147