Hot stage XRD

Hot-stage XRD. The sample is placed inside a quartz furnace tube that can be heated to temperatures up to 1600°C often in a range of different atmospheres. The main uses are to study phase changes and structural transformations as a function of temperature. 

Figure 2.5 Hot stage XRD demonstrating reversible transition in the melt.

Temperature-dependent xrd-rsm measurement was performed by employing a dhs 900 domed hot stage (Anton Paar) attached to the PANalytical s X Pert pro-mrd system. Figure 6.8 shows an overview of the dhs 900 domed hot stage. The sample is mounted on... 

Once this initial characterization has been completed, continuation of the microscopic analysis using the hot-stage accessory may proceed. As an initial analysis, the ramp rate utilized for the DSC experiment should also be used for the hot-stage analysis. Use of a consistent ramp rate permits direct comparison of the data previously collected by DSC and TGA. If transitions are observed in the thermal data up to 300°C, the hot-stage experiment should also be run to that temperature. Ultimately, the assay should be conducted to generate confirmatory data on all transitions of interest. If available, the color camera should be utilized so that images may be collected as documentation of the transitions observed. Once the experiment is completed, the analyst may be able to compare the DSC, TGA, XRD, optical, and HSM data and develop a comprehensive characterization of the material. 

Additional assays may also be conducted on this material to more comprehensively characterize its thermal properties. The following may be considered variable temperature XRD (VT-XRD) studies may be conducted to observe changes in the powder diffraction patterns of the material as a function of temperature. Selection of appropriate temperatures depends on several factors the DSC transition temperatures, corroborating TGA and hot-stage evidence, and the accuracy of the heating controller for the XRD unit. It should also be noted that although XRD data may be collected at several different temperatures to simulate a variable temperature experiment, the follow-up VT-XRD assay is essentially a series of isothermal experiments, and the DSC is a dynamic assay. It is therefore reasonable to expect some variation in transition temperatures. 

Because no additional physical characterization information was available on this material, HSM was employed to assist in identifying the transitions observed in the DSC curve. Figure 7.34 to Figure 7.36 are representative photomicrographs (collected at 400x with slightly uncrossed polarizers) from the hot-stage experiments that support the data collected from DSC, TGA, and XRD assays. 

These application examples, in conjunction with the DSC, TGA, XRD, and hot-stage photomicrographs, hopefully illustrate the theme that no single analytical technique can completely characterize a material. The utilization of multiple techniques is required to conduct a comprehensive characterization of the physical properties of materials, because each technique provides a particular piece of information that is necessary for the characterization of unknowns, process materials, compounds under development, etc. 

Reel] [1967Ree2] XRD, hot stage optical microscopy 1085°C isothermal section, CaO-FeO-Fc203. liquidus surface. 

In-situ XRD was used to assess the thermal stability of the beta zeolite support and the Cu/beta catalyst. The powder samples were mounted on the hot-stage in the sample chamber under a flowing 20 % O2/8O % N2 gas mixture. The temperature was increased from room temperature to 970 °C at a 10 °C/min ramping rate. Two dwells were included in the heating profile, each an hour long, at 900 and 970 °C. XRD data sets were collected at 55 °C increments, or 5-min intervals. Finally, an XRD scan was recorded when the sample was cooled to room temperature. 

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