Graphite has been widely used as a negative electrode material in lithium-ion batteries, and recently it has attracted attention for its use in potassium-ion batteries. In this study, the first in situ X-ray diffraction characterisation of a K/graphite electrochemical cell is performed. Various graphite intercalation compounds are found, including the stage three KC36 and stage one KC8 compounds, along with the disappearance of the graphite during the potassiation process. These results show new insights on the non-equilibrium states of potassium-ion intercalation into graphite in K/graphite electrochemical cells.

The thermal decomposition of mill scale, and the effect of mill scale addition on the formation and decomposition of Silico-Ferrite of Calcium and Aluminium (SFCA) and SFCA-I iron ore sinter bonding phases, has been investigated using in situ X-ray diffraction. Application of the external standard method of quantitative phase analysis of the in situ data collected during decomposition of the mill scale highlighted the applicability of this method for the determination of the nature and abundance of amorphous material in a mineral sample. Increasing mill scale addition from 2.6 to 10.6 and to 21.2 wt% in an otherwise synthetic sinter mixture composition designed to form SFCA did not significantly affect the thermal stability ranges of SFCA-I or SFCA, nor did it significantly affect the amount of each of SFCA or SFCA-I, which formed. This was attributed to the low impurity (i.e. Mn, Mg) concentration in the mill scale, and also the transformation to hematite during heating of the wüstite and magnetite present in the mill scale, with the hematite available for reaction to form SFCA and SFCA-I.

The microstructure evolution (crystallite size and microstrain) as well as the residual stress of Cu thin films of various thicknesses (250 nm, 500 nm, and 1 μm) on passivated Si substrates during isochronal annealing was investigated by in situ X-ray diffraction measurements in the temperature range between 25 °C and 250 °C. Before annealing, the thermoelastic behavior was investigated excluding the occurrence of thermally activated relaxation processes occurring above ambient temperature by in situ stress measurements below ambient temperature. On this basis, above ambient temperature, effects of stress relaxation and emerging secondary stresses (due to grain growth and annihilation of crystal defects, giving rise to a considerable tensile stress contribution development) could be identified for all three layers in the temperature regime between ambient temperature and 250 °C. Grain growth in the nanocrystalline thin films started at much lower temperatures as compared to coarse-grained materials. The results were discussed in terms of the effects of different driving forces and grain-boundary mobilities acting in nanocrystalline materials.

This paper describes a method to determine the equilibrium transformation temperatures in low C steels using the in situ high-temperature X-ray diffraction technique. The samples were heated and then cooled from 1000 to 720 °C in a stepwise manner decreasing to −10 °C. Austenite and ferrite fractions were determined by a quantitative method using the integrated intensities of austenite (111)γ and ferrite (110)α peaks from X-ray diffraction patterns. The effect of the temperature on interplanar d spacings of (111) and (110) crystallographic planes was determined using 2θ maximum positions of the austenite (111)γ and ferrite (110)α peaks. The equilibrium transformation temperatures were determined to be Ae1=720 °C and Ae3=950 °C. The results are in excellent agreement with those obtained by dilatometric analysis and Thermo-Calc phase diagram simulation software. In addition, the results were supported by microstructural observations: the formation of thin ferrite films (5–10 μm) was observed at temperatures near to experimental Ae3.

In situ X-ray diffraction was used to study the interactions of the PNNL G18 fuel cell sealing glasses with the oxides that form on candidate interconnect alloys and with the ebrite alloy. Experiments under 4% hydrogen and air at temperatures up to 1000 °C showed that the sealant reacts rapidly with alumina and chromia, but not with NiO. The crystallization of the high-CTE phase BaCrO4 was noted for G18 in contact with chromia or ebrite under air, but reducing conditions inhibit the crystallization. The reactions in all cases begin within a few hours at temperatures above 800 °C and go to completion or near completion after ∼12 h.