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We analyzed a number of complicated X-ray diffraction patterns using feature patterns obtained through unsupervised machine learning. A crystalline SiGe film on a Si substrate with a spatial fluctuation in both composition and crystal orientation was tested as a model sample having complicated X-ray diffraction patterns with multipeaks. Non-negative matrix factorization (NMF), an unsupervised machine learning method, was performed on 961 patterns obtained by spatial mapping of micro-beam X-ray diffraction measurements. Among the tested number of the feature patterns from 1 to 10, four feature patterns were the most useful for extracting the information about the composition and crystal orientation because they correspond to the diffraction patterns of typical SiGe films with high and low Si fraction, and right- and left-tilted orientation. Reasonable spatial maps of composition and crystal orientation were visualized using coefficients of the four feature patterns. Furthermore, the spatial constraint was tested for NMF using 225 diffraction patterns which were down-sized from 33 × 33 to 16 × 16 pixels due to the high computational cost of simple implementation without techniques to reduce the cost. Four feature patterns similar to those of the simple NMF without the constraints and the more reasonable distribution reflecting the SiGe spatial domain structure were obtained. The feature pattern extraction by NMF and interpretation by experts demonstrated in this study will be useful for quick analysis of a number of X-ray diffraction patterns with large and complicated fluctuations.

The solidification process of Ni-based superalloy K465 was examined using DTA and X-ray diffraction. The impact of melt structure on solidification process and the morphology of MC carbide and γ′-phase was analyzed. It was observed that an increase in melt peak temperature led to a significant decrease in precipitation temperature for carbides, but only a slight increase in the formation temperature of matrix and eutectic microstructure. The X-ray diffraction results showed that some ordered structures were detected in the sample with melt peak temperature of 1450 °C and 1500 °C, but not in the sample with melt peak temperature of 1360 °C. Furthermore, the ordered structure displayed similar crystalline features with M6C carbide. As the melt peak temperature increased, the carbides changed from block type to script type morphology. This phenomenon was likely caused by the formation of ordered structures at high temperatures. However, the microstructure of γ matrix and γ′ precipitates remained unaffected by the melt peak temperature.

The results of obtaining titanium carbide by a vacuum-free electric arc method using various types of biocarbon obtained by classical pyrolysis of biomass waste, such as tangerine peel, pomelo peel, banana peel, pine nut shells, and walnut shells, are presented. An analysis of X-ray diffraction patterns of the synthesized materials showed the repeatability of the experiment with the receipt of diffraction maximums indicating the formation of a cubic structure of titanium carbide. An analysis of the thermal oxidation of the resulting powders showed that the process proceeded slowly up to 1000°C, but the rate of oxidation increased significantly with temperature. It has been established that the weight of the studied titanium carbide powders obtained using various types of carbon increased upon thermal heating in an oxidizing atmosphere, as confirmed by thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

Glasses of Sb2S3-As2S3 system with nominal composition of As0,4xSb0,4(100-x)S60 (where x= 10, 25, 50, 75 and 100 mol% As2S3) were investigated by different quenching methods and Raman spectroscopy. All studied samples were in the vitreous state. The average coordination number (Z), being equal to 2.4, has indicated that the numbers of neighbors of non-chalcogens (As and Sb) and chalcogens (S and Te) atoms were respectively 3 and 2. These coordination numbers were conditions fulfilled by the atoms to obtain vitreous materials. The vibrations of the SbS3 and AsS3 structural units dominated the Raman spectra of the studied Sb2S3-As2S3 glasses. [ABSTRACT FROM AUTHOR]

This study investigated the role of water in the high-pressure treatment (300–600 MPa/15 min) of buckwheat (Fagopyrum esculentum) flour and property changes in post-process samples. DSC and XRD measurements demonstrated complete gelatinization of buckwheat starch occurred at 600 MPa. The particle size of flour decreased above 450 MPa. HP-treatment successfully transformed the crystalline A-type structure of hydrated samples into a B-type structure. Dry samples did not gelatinize or exhibit any structural change, even at 600 MPa. The progress of gelatinization and gel rigidity of post-process samples were measured on a rheometer. The thermal transition captured in rheometer and DSC differs significantly. The impact of further heating on the pressurized samples resulted in a significant improvement in their mechanical rigidity. Overall, this study confirmed that an optimum flour-to-water ratio should be maintained during HP treatment to achieve the desired changes in buckwheat flour so that it could be used in food formulation. [Display omitted] • Dry and hydrated buckwheat flours were treated under high-pressure. • The dry sample did not gelatinize, even at 600 MPa. • Hydrated samples showed significant changes in functional and structural properties. • A change in polymorph structure from A-type to B-type occurred in the treated sample. • Cracks developed in pressure-treated samples. [ABSTRACT FROM AUTHOR]

In this work, a new BN polymorph with Pnma symmetry is proposed by RG2 and investigated by density functional theory. Pnma -II BN polymorph is shown to be dynamically and mechanically stable, and the relative enthalpy of Pnma -II BN is 0.187 eV per atom higher than that of c-BN, respectively. Mechanical properties calculations indicate that Pnma -II BN is also a potential superhard material with hardness of 49.7 GPa. The electronic band structures of Pnma -II BN show that the Pnma -II BN is a direct and ultrawide band gap semiconductor (band gap is 5.82 eV). The mechanical anisotropy of Young's modulus of Pnma -II BN and Pnma BN is greater than that of c-BN, while the mechanical anisotropy of shear modulus of Pnma -II BN in the (100), (001) plane is lower than that of c-BN. In addition, simulated X-ray diffraction patterns are provided for experimental confirmation of the predicted structures. [Display omitted] [ABSTRACT FROM AUTHOR]