Material Science for Environmental Sustainability Research Unit, School of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok, 10520, Thailand.
Municipal Waste and Wastewater Management Learning Center, School of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok, 10520, Thailand.
Sci Rep. 2022 Apr 27;12(1):6869. doi: 10.1038/s41598-022-11056-4.
The solid-state reaction was employed to synthesize CaCuPO by varying the mole ratio between Ca and Cu. The structure and crystallography of the pyrophosphate compounds were identified and confirmed by using X-ray diffraction (XRD). The Rietveld refinement method and the extended X-ray absorption fine structure (EXAFS) least-squares fitting technique were also applied to refine the sample crystal structure. The single phases of the obtained CaPO, CaCuPO, and CuPO samples and the mixing phases of the obtained CaCuPO and CaCuPO samples were identified, and then only a single phase of the samples was subjected to structural and dielectrical analyses. The structural results exhibit the tetragonal crystal system with the P4 space group for β-CaPO, the monoclinic crystal system with the P2/c space group for CaCuPO, and the C2/c space group for α-CuPO. The dielectric constant (ε) of the single metal pyrophosphates (CaPO and CuPO) was higher than that of binary metal pyrophosphates (CaCuPO). The image sensor result of the CuPO sample (x = 2.00) illustrated a yellowish-green color, while other compounds (x = 0.50-1.50) presented color tones that changed from blue-green to bluish-green. Raman and Fourier transform infrared (FTIR) spectrophotometers were employed to characterize and confirm the vibrational characteristics of the PO group, which contains the O-P-O radical ([PO]) and the P-O-P bride ([OPO]) and approximate M-O stretching modes. Furthermore, this work reports for the first time that the change in the crystal structure of CaCuPO (i.e., bond angle of P-O-P in PO and distortion phenomena in the M-O octahedral site) are cause the correlation between the structure, chromaticity, and dielectric properties of calcium copper pyrophosphates, CaCuPO.
采用固相反应用不同的钙铜摩尔比合成 CaCuPO。使用 X 射线衍射（XRD）确定和确认焦磷酸盐化合物的结构和晶体学。Rietveld 精修方法和扩展 X 射线吸收精细结构（EXAFS）最小二乘拟合技术也应用于样品晶体结构的精修。获得了 CaPO、CaCuPO 和 CuPO 样品的单相和获得的 CaCuPO 和 CaCuPO 样品的混合相，然后仅对样品的单相进行结构和介电分析。结构结果表明，β-CaPO 具有四方晶系 P4 空间群，CaCuPO 具有单斜晶系 P2/c 空间群，α-CuPO 具有 C2/c 空间群。单相金属焦磷酸盐（CaPO 和 CuPO）的介电常数（ε）高于二元金属焦磷酸盐（CaCuPO）。CuPO 样品（x=2.00）的图像传感器结果呈现出黄绿色，而其他化合物（x=0.50-1.50）呈现出从蓝绿色到青绿色的色调变化。拉曼和傅里叶变换红外（FTIR）分光光度计用于表征和确认 PO 基团的振动特性，该基团包含 O-P-O 自由基([PO])和 P-O-P 桥([OPO])以及近似的 M-O 伸缩模式。此外，本工作首次报道了 CaCuPO 晶体结构的变化（即 PO 中 P-O-P 的键角和 M-O 八面体位的扭曲现象）是导致钙铜焦磷酸盐 CaCuPO 的结构、色度和介电性能之间相关的原因。
