X-ray powder diffraction quantitative analysis performedin situat high temperature: application to the determination of NiO in ceramic pigments

Abstract

Although nickel(II) oxide (NiO) is a potential carcinogenic agent, it is still used in the synthesis of ceramic pigments because during their preparation at high temperature, NiO is thought to combine with other compounds, crystallizing as new phases with spinel-like structures. Unfortunately, there are no widely accepted methods for the determination of free NiO in ceramics, the main reason being experimental dif®culties. In fact, quantitative phase analysis (QPA) by X-ray powder diffraction (XRPD) may fail because diffraction peaks of NiO with space group Fm3 Å m and a 9 4.18 A Ê overlap with those of the spinel with space group Fd3 Å m and a 9 8.4 A Ê . To overcome this problem, in this work QPA has been performed in situ at high temperature to resolve the peak overlap of NiO and spinel by taking advantage of the different thermal expansion of each phase. It is believed that this is the ®rst report of the application of this technique.

Full reciprocal-space mapping up to 2000 K under controlled atmosphere: the multipurpose QMAX furnace

“…Although such setups have been widely used, accurate sample positioning as a function of temperature is still a difficult task (Brown et al, 1993;Misture et al, 2002;Beck & Mittemeijer, 2002), and sample displacement with respect to the goniometer axes has a large influence on the accuracy of the d-spacing measurements (Masson et al, 1996). This drawback can be overcome by using cylindrical furnaces in which the samples are put on top of an alumina disc located on a spinning stage that corresponds to azimuthal rotation around the sample surface (Gualtieri et al, 1999;Estermann et al, 1999;Guinebretiè re et al, 2007). Heating of the samples is usually realized using conventional high-temperature heaters located around the sample holder.…”

“…Heating of the samples is usually realized using conventional high-temperature heaters located around the sample holder. Combination of this setup with a translational stage along the azimuthal ' rotation axis allows one to continuously compensate the sample holder thermal expansion (Gualtieri et al, 1999;Guinebretiè re et al, 2007). One of the most significant achievements using this configuration is certainly the furnace built by Yashima et al (2006) on the 4B2 beamline at the Photon Factory in Japan.…”

Rietveld quantitative amorphous content analysis

“…RQA is the subject of much research effort. This tool has been extended to in situ studies at high temperature to resolve peak overlap, taking advantage of the different thermal expansions of different phases (Gualtieri et al, 1999). The errors associated with such quantitative analyses are also the subject of study (Toraya, 1999(Toraya, , 2000.…”

Removal of Agrochemicals from Waters by Adsorption: A Critical Comparison among Humic-Like Substances, Zeolites, Porous Oxides, and Magnetic Nanocomposites

“…The description of the details of this sequence of operations can be found in [58,82]. These two samples of nanocomposites were subjected to quantitative phase determinations by the combined RIR-Rieveld method [83][84][85] which gave the results summarized in Table 4. Moreover, these two samples of nanocomposites were subjected to: (1) textural and morphological characterization, whose main results are summarized in Table 5; (2) TEM characterization.…”