Low-temperature structural phase transition in synthetic libethenite Cu2PO4OH

Twinned olivenite from Cap Garonne, Mine du Pradet – structure and magnetic behavior

Systematically twinned olivenite (Cu2(AsO4)OH) single crystals from Cap Garonne, Mine du Pradet, France, were studied by X-ray diffraction: P 21/n, a = 822.69(6) pm, b = 861.88(9) pm, c = 594.06(9) pm, β = 90.000(6)°, wR = 0.0224, 1621 F 2 values, 79 variables and a domain ratio of 0.501(1)/0.499(1). The temperature dependence of the magnetic susceptibility was well reproduced with a square-spin cluster model and an antiferromagnetic spin-exchange parameter of J/k B = 157(3) K.

Fabricating Metallic Circuit Patterns on Polymer Substrates through Laser and Selective Metallization

Nowadays, with the rapid development of portable electronics, wearable electronics, LEDs, microelectronics, and bioelectronics, the fabrication of metallic circuits onto polymer substrates with strong adhesion property is an ever-increasing challenge. In this study, the high-resolution and well-defined metallic circuits were successfully prepared on the polymer surface via laser direct structuring (LDS) based on copper hydroxyl phosphate [Cu₂(OH)PO₄], and the key mechanism of the selective metallization was systematically investigated. XPS confirmed that Cu⁰ (elemental copper) was formed through photochemical reduction reaction of Cu₂(OH)PO₄, after 1064 nm NIR pulsed laser irradiation. During the electroless plating, because it is the important active catalytic center, this newly formed Cu⁰ was the key factor to achieve the successful selective metallization. SEM revealed that after the electroless plating, the copper layer actually physically anchored into the polymer substrate, giving an excellent mechanical adhesion property of the obtained metallic patterns. In addition, the micro-Raman surface imaging approved the generation of the amorphous carbon on the polymer composites' surface after NIR laser irradiation, and the chemical reaction region caused by the pulsed laser spot was found at approximately 40 μm. This environmentally friendly and effective strategy for fabricating circuit patterns on the polymer surface has a possible application in the printed circuit plate (PCB) industry.

High pressure structural and vibrational properties of the spin-gap system Cu2PO4(OH)

The structural and vibrational properties of the spin-gapped system Cu(2)PO(4)(OH) have been investigated at room temperature under high pressure up to ~20 GPa by Raman scattering and synchrotron-based x-ray diffraction and infrared (IR) spectroscopic measurements. The orthorhombic phase (space group Pnnm, z = 4) remains stable up to at least 7 GPa where it undergoes a weakly first order structural transition (with negligible volume drop) to a monoclinic phase (space group P2(1)/n, z = 4) with an abrupt monoclinic distortion. Refinement of atomic positions has been performed for the low pressure phase. The conspicuous changes in the vibrational spectra (Raman as well as far-IR) confirm this phase transition. At further higher pressures the monoclinic angle increases rapidly and the system transforms irreversibly into a disordered phase. Detailed vibrational analyses have been performed in the orthorhombic phase and pressure-induced structural evolution has been correlated with the vibrational modes corresponding to the Cu-O bonds. A strong negative pressure dependence of hydroxyl mode frequencies (as observed from the mid-IR absorption spectra) supports the pressure-induced structural disordering at higher pressures.