We report on the magneto-structural properties of the rare copper aluminum hydroxo-arsenate mineral liroconite with chemical composition Cu2AlAs1−x P x O4(OH)4·4H2O (x ≈ 0.2). In order to characterize the natural mineral sample chemical analyses, X-ray single crystal and powder diffraction, heat capacity and crystal water desorption, anisotropic thermal expansion and Raman scattering and magnetic susceptibility investigations have been carried out. The magnetic properties are well described by two discrete oxygen bridged Cu2+ spin S = 1/2 dimers with antiferromagnetic spin exchange ranging between −320 K and −136 K, depending on to which group-15 five-valent cation, As5+ or P5+, the dimer bridging oxygen atoms coordinate to. Accordingly the temperature dependence of the magnetic susceptibilities can be well fitted to a sum of two Bleaney–Bowers type spin S = 1/2 dimer susceptibilities suggesting that the dimers show negligible mixed coordination to (AsO4)3−/(PO4)3− tetrahedra. DFT + U calculation confirm the ratio of the spin exchange parameters of the (AsO4)3− or (PO4)3− coordinated Cu2+ – Cu2+ dimers. Inter dimer spin exchange is about two orders of magnitude smaller than intra dimer exchange.

中文翻译：

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Liroconite Cu2Al(As,P)O4(OH)4·4H2O中的多重强耦合反铁磁自旋S = 1/2二聚体

我们报告了化学成分为 Cu 的稀有铜铝羟基砷酸盐矿物 liroconite 的磁结构特性2唉1−X 磷 X ○4（哦）4·4小时2Ø (X≈ 0.2)。为了表征天然矿物样品的化学分析，进行了 X 射线单晶和粉末衍射、热容量和结晶水解吸、各向异性热膨胀和拉曼散射和磁化率调查。两个离散的氧桥接铜很好地描述了磁性2+旋转小号= 1/2 二聚体，反铁磁自旋交换范围在 -320 K 和 -136 K 之间，取决于哪个第 15 组五价阳离子，As5+或 P5+，桥接氧原子的二聚体配位到。因此，磁化率的温度依赖性可以很好地拟合两个 Bleaney-Bowers 型自旋的总和小号= 1/2 二聚体敏感性表明二聚体与 (AsO4)3−/(PO4)3−四面体。DFT +ü计算证实了（AsO的自旋交换参数的比率4)3−或 (PO4)3−配位铜2+– 铜2+二聚体。二聚体间自旋交换比二聚体内交换小两个数量级。