The Heat Treatment Process and Color Mechanism of Green
Fluor-Hydroxyapatite
YUE Su-wei1*, YAN Xiao-xu2*, CHEN Si-min2, LUO Jie2
1. Jewelry Institute, Guangzhou Polytechnic University, Guangzhou 511483, China
2. School of Jewelry, Guangzhou City University of Technology, Guangzhou 510800, China
Abstract:Apatite is widely used as an inorganic non-metallic material, a geological indicator mineral, and a common gemstone variety. The chemical formula for apatite is [Ca10(PO4)6(F, Cl, OH)2], Ca2+sites can be isomorphously substituted by divalent transition metal cations (Fe2+, Mn2+, etc. ), rare earth element ions (La3+, Ce3+, Gd3+, etc. ), or alkali and alkaline earth metal ions (K+, Na+, Sr2+, etc. ), resulting in various colors such as yellow, green, blue, purple, and photochromic effects. Green fluor-hydroxyapatite turns into a bright blue hue after heat treatment at 650~700 ℃, possessing high ornamental and commercial value. The results show that the samplesare mainly composed of Ca2+ and P5+ with a small amount of N5+, which is mainly substituted [PO3] in the form of —NH2, indicating biochemical behavior correlated in formation. UV-Vis results show that the sample's color is mainly caused by the isomorphic substitution of Ce3+ and Mn2+ in the distorted octahedron of Ca2+, forming a blue-green transmission window. The defects in the green apatite sample before heat treatment are mainly ionic centers F--O--F-, combining with O2--O--V and OH--O--V, caused by the isomorphic substitution of Ce3+ at the CaⅠ site. After heat treatment, the recovery of hole centers is mainly manifested as ionic center defects caused by Mn2+ substituting the distorted octahedron at CaⅠ and CaⅡ sites. Combining EPR spectra shows that Mn2+ can be distributed at both CaⅠ and CaⅡ positions, causing a blue hue in the samples; otherwise, when Ce3+ is highly substituted at the CaⅠ position, the samples turn green.
Key words:Green apatite; Heat treatment; Color mechanism; EPR spectra
岳素伟,剡晓旭,陈思敏,罗 洁. 绿色氟羟磷灰石热处理及颜色成因探究[J]. 光谱学与光谱分析, 2025, 45(07): 1961-1967.
YUE Su-wei, YAN Xiao-xu, CHEN Si-min, LUO Jie. The Heat Treatment Process and Color Mechanism of Green
Fluor-Hydroxyapatite. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2025, 45(07): 1961-1967.
[1] Ketcham R A. American Mineralogist, 2015, 100(7): 1620.
[2] XING Kai, SHU Qi-hai(邢 凯, 舒启海). Mineral Deposits(矿床地质), 2021, 40(2): 189.
[3] Stock M J, Humphreys M C S, Smith V C, et al. Journal of Petrology, 2018, 59(12): 2463.
[4] Piper W W, Prener J S. Physical Review B, 1972, 6(7): 2547.
[5] Iskhakova K, Murzakhanov F, Mamin G, et al. IOP Conf. Series: Earth and Environmental Science, 2018, 155: 012002.
[6] Kamal H, Hezma A M. Physical Science International Journal, 2015, 7(3): 137.
[7] Pan Y M, Dong P, Chen N. Geochimica et Cosmochimica Acta, 2003, 67(10): 1889.
[8] Hammerli J, Hermann J, Tollan P, et al. Contributions to Mineralogy and Petrology, 2021, 176(12): 105.
[9] Zhou Q, Dolgov L, Srivastava A M, et al. Journal of Materials Chemistry C, 2018, 6(11): 2652.
[10] CHEN Chao-yang, HUANG Wei-zhi, SHAO Tian, et al(陈超洋, 黄伟志, 邵 天, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2021, 41(5): 1483.
[11] Zhang Z Y, Xu B, Yuan P Y, et al. Crystals, 2022, 12(8): 1067.
[12] Chindudsadeegul P, Jamkratoke M. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2018, 204: 276.
[13] Drouet C. Journal of Chemical Thermodynamics, 2019, 136: 182.
[14] Gilinskaya L G, Mashkovtsev R I. Journal of Structural Chemistry, 1995, 36(1): 76.
[15] Hughes J M, Rakovan J F. Elements, 2015, 11(3): 165.
[16] Tao J H. Methods in Enzymology, 2013, 532: 533.
[17] Grunenwald A, Keyser C, Sautereau A M, et al. Journal of Archaeological Science, 2014, 49: 134.
[18] TU Jiang-lei, GUO Fu-qiang, LÜ Chun-chun, et al(涂姜磊, 郭富强, 吕春春, 等). Journal of Biomedical Engineering(生物医学工程学杂志), 2011, 28(1): 99.
[19] Zhang C T, Chen C Y, Li Z B, et al. Minerals, 2023, 13(9): 1139.
[20] Pan Y M, Chen N, Weil J A. American Mineralogist, 2002, 87, 10: 1333.
[21] CAI Xiu-cheng, FU Yu-de, TANG Rong-bing(蔡秀成, 富毓德, 唐荣炳). Acta Mineralogica Sinica(矿物学报), 1981,1(2): 77.
[22] Mayer I, Cuisinier F J G, Popov I, et al. European Journal of Inorganic Chemistry, 2006, 7: 1460.