Abstract A new method for the synthesis of various types of copper(II) formates with Cu(NO3)2∙3H2O and formic acid, orthorhombic (α) and monoclinic (β) modifications of anhydrous copper(II) formate, as well as Cu(HCOO)2∙2H2O and Cu(HCOO)2∙4H2O. The identity of the obtained compounds was confirmed by X-ray phase analysis, optical microscopy and thermogravimetry methods. It was shown that Cu(HCOO)2∙4H2O can be used as a precursor for producing copper powders with particle size of the order of 150 nm. The results of investigation of vibration and absorption spectra of α and β modifications of anhydrous copper(II) formate are presented. Their magnetic behavior in the temperature interval 2–300 K was estimated, and comparative analysis of magnetic properties was carried out. First-principle calculations of electronic band structure for anhydrous α and β modifications were performed. The results obtained correspond to experimentally observed structural instability of β-Cu(HCOO)2, fundamental absorption edge enhancement during transition from α to β modification, and low-temperature ferromagnetic ordering in α-Cu(HCOO)2. Simulation for β modification is indicative of antiferromagnetic ordering of magnetic moments inside chains formed by copper-oxygen octahedra.

中文翻译：

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生产甲酸铜 (II) 的新方法及其热、光谱和磁特性

摘要 一种用 Cu(NO3)2∙3H2O 和甲酸、无水甲酸铜 (II) 的正交 (α) 和单斜 (β) 变体以及 Cu 合成各种类型甲酸铜 (II) 的新方法(HCOO)2∙2H2O 和 Cu(HCOO)2∙4H2O。所得化合物的身份通过 X 射线相分析、光学显微镜和热重法确定。结果表明，Cu(HCOO)2∙4H2O 可用作制备粒径为 150 nm 数量级的铜粉的前驱体。介绍了无水甲酸铜 (II) 的 α 和 β 变体的振动和吸收光谱的研究结果。估计了它们在 2-300 K 温度区间的磁行为，并进行了磁性能的比较分析。进行了无水 α 和 β 修饰的电子能带结构的第一性原理计算。获得的结果对应于实验观察到的 β-Cu(HCOO)2 的结构不稳定性、从 α 到 β 改性过渡期间的基本吸收边缘增强以及 α-Cu(HCOO)2 中的低温铁磁有序。β 修饰的模拟表明由铜氧八面体形成的链内磁矩的反铁磁排序。