High-Resolution Microstructure Characterization of Additively Manufactured X5CrNiCuNb17-4 Maraging Steel during Ex and In Situ Thermal Treatment

Powder and selective laser melting (SLM) additively manufactured parts of X5CrNiCuNb17-4 maraging steel were systematically investigated by electron microscopy to understand the relationship between the properties of the powder grains and the microstructure of the printed parts. We prove that satellites, irregularities and superficial oxidation of powder particles can be transformed into an advantage through the formation of nanoscale (AlMnSiTiCr) oxides in the matrix during the printing process. The nano-oxides showed extensive stability in terms of size, spherical morphology, chemical composition and crystallographic disorder upon in situ heating in the scanning transmission electron microscope up to 950 °C. Their presence thus indicates a potential for oxide-dispersive strengthening of this steel, which may be beneficial for creep resistance at elevated temperatures. The nucleation of copper clusters and their evolution into nanoparticles, and the precipitation of Ni and Cr particles upon in situ heating, have been systematically documented as well.

Crystal structure of a new polyoxometalate (POM) compound with a high level of crystallographic disorder

The crystal structure, Hirshfeld surface analysis and spectroscopic analysis of a new polyoxometalate (POM) compound, namely, nonakis(2-methoxyaniline) bis(diphosphopentamolybdate) trihydrate, (C7H9NO)9[P2Mo5O23]2·3H2O, is reported. The title compound was synthesized using the solution method and was structurally characterized by single-crystal X-ray diffraction, which revealed P\overline{1} symmetry. A study of the intermolecular interactions using Hirshfeld surface analysis confirmed that the hydrogen-bonding interactions play the dominant role in the stability of the crystal structure. The refinement was complicated by extensive disorder affecting 11 of the 16 ions and molecules in the asymmetric unit. IR and UV–Vis spectroscopic techniques were used to identify the vibrational modes and to classify this compound as an insulator.

Uncertainty Estimates for Magnetic Relaxation Times and Magnetic Relaxation Parameters

We describe a method for obtaining uncertainties in magnetic relaxation times from AC susceptibility experiments. We provide a program for fitting AC data and the resulting magnetic relaxation times accounting for the uncertainties correctly, to give magnetic relaxation parameters with accurate uncertainties. We show that the implicit distributions in the magnetic relaxation times have large consequences for the uncertainties in the model parameters, and that the magnitude of these uncertainties appear to correlate with crystallographic disorder in three families of high-performance Dy(III) single-molecule magnets.

Uncertainty Estimates for Magnetic Relaxation Times and Magnetic Relaxation Parameters

We describe a method for obtaining uncertainties in magnetic relaxation times from AC susceptibility experiments. We provide a program for fitting AC data and the resulting magnetic relaxation times accounting for the uncertainties correctly, to give magnetic relaxation parameters with accurate uncertainties. We show that the implicit distributions in the magnetic relaxation times have large consequences for the uncertainties in the model parameters, and that the magnitude of these uncertainties appear to correlate with crystallographic disorder in three families of high-performance Dy(III) single-molecule magnets.

Synchrotron radiation diffraction study of the mineral moolooite, and synthetic copper oxalates

The orthorhombic mineral moolooite, CuC2O4. nH2O, described by Clarke and Williams (1986) using Debye-Scherrer photographic data, has a fully-disordered stacking fault (FDSF) structure. Related monoclinic models have been reported for various synthesised samples based on Schmittler (1968). In the present study, synchrotron radiation diffraction data for moolooite and synthesised specimens have been examined with particular reference to crystallographic disorder. The moolooite data correspond to space group Pnnm, with a = 5.3064(2), b = 5.6804(2), c = 2.5630(1) Å; Vc = 77.26(1) Å3; and Z = 1; and the FDSF structure along the b-direction has been confirmed. The synthetic specimen data from the study indicate partial ordering, with space group P21/n; and the cell parameters for one specimen being a = 5.957(7), b = 5.611(5), c = 5.133(7) Å; β = 115.16(2)°; Vc = 155.27 Å3 and Z = 2. The level of zeolitic water in the materials has been considered using the approach of Schmittler based on thermogravimetry and pycnometry. The new data for natural topotype material correspond to CuC2O4.1.0H2O. It is postulated that the level of water for natural and synthetic specimens may be attributed to the conditions under which the material forms.