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Cation reducibility of LaNi0.5Ti0.5O3, LaNi0.5Ti0.45Co0.05O3, and LaNi0.45Co0.05Ti0.5O3 perovskites from X-ray powder diffraction data using the rietveld method

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POWDER DIFFRACTION 2022年第2期37卷 84-90页

作者： Guaman-Ayala, Mayra Tuza, Pablo V. Souza, Mariana M. V. M. Univ Fuerzas Armadas ESPE Carrera Petroquim Dept Energia & Mecan EC170501 Sangolqui Ecuador Univ Fed Rio De Janeiro UFRJ Escola Quim Ctr Tecnol Bloco ESala 206 BR-21941909 Rio De Janeiro RJ Brazil

In the present work, LaNi0.5Ti0.5O3, LaNi0.5Ti0.45Co0.05O3, and LaNi0.45Co0.05Ti0.5O3 perovskites were synthesized using the modified Pechini method. After reduction, the studied perovskites changed crystal structure from the perovskite crystal structure to a cubic symmetry, with space group Pm (3) over barm. The reduction partially decomposed the samples to Ni-0 (Co free perovskite), Ni-0-Co-0, La2O3, La2TiO5, and non-stoichiometric La2NiO4, depending on H-2 content of the reductive gases. The degree of reduction of nickel from LaNi0.5Ti0.5O3 reduced with 1.8% H-2/Ar and 10% H-2/Ar was equal to 36.5% and 95.3%, respectively, while that from LaNi0.5Ti0.45Co0.05O3 or LaNi0.45Co0.05Ti0.5O3, including cobalt, reduced with 10% H-2/Ar, was equal to 71.9% and 93.9%, respectively. LaNi0.5Ti0.45Co0.05O3 showed Ni3+ and Co3+ amounts higher than the other perovskites. By increasing H-2 content in the reductive mixture from 1.8% to 10%, sintering of metallic nickel was not observed. Moreover, Ni-0 displayed weaker metal-support interaction than that observed for Co-0, where the support was composed of La containing oxides. LaNi0.5Ti0.5O3 perovskite was used as a catalyst for steam reforming of methane. Syngas production was attributed to the number of Ni sites determined using rietveld Refinement of X-ray diffraction pattern of this catalyst after the reaction. (C) The Author(s), 2022. Published by Cambridge University Press on behalf of International Centre for Diffraction Data.

关键词： reducibility X-ray diffraction rietveld method perovskite quantitative phase analysis

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The effect of data quality and model parameters on the quantitative phase analysis of X-ray diffraction data by the rietveld method

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JOURNAL OF APPLIED CRYSTALLOGRAPHY 2021年第3期54卷 878-894页

作者： Rowles, Matthew R. Curtin Univ John de Laeter Ctr Perth WA Australia

The quality of X-ray powder diffraction data and the number and type of refinable parameters have been examined with respect to their effect on quantitative phase analysis (QPA) by the rietveld method using data collected from two samples from the QPA round robin [Madsen, Scarlett, Cranswick & Lwin (2001). J. Appl. Cryst. 34, 409-426]. From the analyses of these best-casescenario specimens, a series of recommendations for minimum standards of data collection and analysis are proposed. It is hoped that these will aid new QPA-by-rietveld users in their analyses.

关键词： powder diffraction quantitative phase analysis rietveld method ruggedness

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Quantitative analysis and evaluation of solid-state stability of mebendazole Forms A and C suspensions by powder X-ray diffraction using the rietveld method

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INTERNATIONAL JOURNAL OF PHARMACEUTICS 2024年 650卷 123721页

作者： Chambi, Julian Ticona Prado, Livia Deris Patricio, Beatriz Ferreira de Carvalho Ceballos, Marcelo Bianco, Ismael Fandaruff, Cinira Rocha, Helvecio V. Antunes Kuznetsov, Alexei Cuffini, Silvia Lucia Univ Fed Sao Paulo UNIFESP Inst Ciencia & Tecnol ICT Sao Paulo SP Brazil Inst Tecnol Farmacos Farmanguinhos FIOCRUZ Lab Micro & Nanotecnol Rio De Janeiro Brazil Univ Fed Estado Rio de Janeiro UNIRIO Lab Farmacol Rio De Janeiro Brazil Ctr Excelencia Prod & Proc Prov Cordoba CEPROCOR Cordoba Argentina Inst Nacl Metrol Qualidade & Tecnol Inmetro Rio De Janeiro Brazil Rua Talim 330 BR-12231280 Sao Jose Dos Campos Brazil

Mebendazole (MBZ) is a broad-spectrum active pharmaceutical ingredient (API) indicated for treating parasitosis, and it has three solid-state forms, A, B, and C. These solid forms exhibit significant differences in dissolution properties, which cause considerable changes in the therapeutic effect. When at least 30 % of Form A is present in the formulation, it has a similar effect to the placebo. The aim of this study was to develop a reliable quantitative method for MBZ (Forms A and C) suspensions that allowed to study the solid-state stability and the kinetics of the solid-state transformation of MBZ suspensions under the recommended pharmaceutical industry conditions. One method was developed to carry out the drying process and the other one to quantify Forms A and C of MBZ suspensions;both were evaluated. For the stability study, samples were prepared with different starting reference concentrations of Form A and stored from 1 to 24 months under long-term stability conditions (30 +/- 2 degrees C and 75 +/- 5 % RH) and from 1 to 6 months under accelerated stability conditions (40 +/- 2 degrees C and 75 +/- 5 % RH). Data collection was performed by powder X-ray diffraction (PXRD). The rietveld method (RM) and Topas's program were used to solid form quantification. Avrami's equation was used to determine the kinetic parameters. The results showed that the combination of the drying process and solid form quantification developed method for suspension was a very accurate methodology for solid-state stability studies. Furthermore, in long-term and accelerated solid-state conditions, suspension with an initial value of 1 % of Form A were sufficient to cause a solid-state transformation (Form C to A) greater than 30 % in the first and second months, with a complete transformation in nine and six months respectively. These results demonstrate that suspensions show complete solid-state transformation (Form C to A) in a shorter time than the product's shelf life (similar to

关键词： Mebendazole Suspensions Stability Kinetics rietveld method Solid-state Quantification

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Study on Mechanism of MSWI Fly Ash Solidified by Multiple Solid Waste-Based Cementitious Material Using the rietveld method

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PROCESSES 2023年第8期11卷 2311页

作者： Wang, Xiaoli Fu, Pingfeng Deng, Wei Shi, Jinjin Xu, Miao Univ Sci & Technol Beijing Sch Civil & Resources Engn Beijing 100083 Peoples R China BGRIMM Technol Grp State Key Lab Mineral Proc Beijing 102628 Peoples R China Cangzhou Municipal Engn Co Ltd Cangzhou 061000 Peoples R China Rd Mat & Technol Engn Res Ctr Hebei Prov Cangzhou 061000 Peoples R China

A novel multiple solid waste-based cementitious material (MSWCM) was developed to immobilize municipal solid waste incineration (MSWI) fly ash. The compressive strength of MSWCM with different ratios of MSWI fly ash reached the standard requirements after curing for 28 days. X-ray powder diffraction (XRD) in combination with the rietveld method was employed to investigate the content and phase transformation of hydration products. The main hydration products of pure MSWCM paste were C-S-H, hydroxyapatite, ettringite and C-A-S-H. With increases in curing time, the content of ettringite and C-A-S-H increased significantly. The main hydration products of MSWCM paste with MSWI fly ash were C-S-H and Friedel's salt. The contents increased markedly with increased curing time from 21.8% to 28.0% and from 8.53% to 16.7%, respectively. Additionally, a small amount of PbHPO4 (0.51-0.96%) and lead phosphate Pb-3(PO4)(2) (0.14-0.51%) were detected, indicating that phosphate had an effective curing effect on lead ions. The results showed that most of the hydration reactions had started at the initial stage of curing and reacted quickly to form a large number of hydration products. The quantitative analyses of hydration products provide essential information for understanding the immobilization mechanism of MSWI fly ash in MSWCM paste.

关键词： cementitious material MSWI fly ash rietveld method multiple solid waste heavy metals solidification X-ray diffraction

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Quantifying the potential for mineral carbonation of processed kimberlite with the rietveld-PONKCS method

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AMERICAN MINERALOGIST 2025年第4期110卷 525-536页

作者： Wang, Baolin Zeyen, Nina Wilson, Sasha Funk, Rebecca Turvey, Connor C. Univ Alberta Dept Earth & Atmospher Sci Edmonton AB Canada Univ Geneva Dept Earth Sci Rue Maraichers 13 CH-1205 Geneva Switzerland

Quantitative phase analysis (QPA) using the rietveld method and X-ray diffraction (XRD) patterns is useful for predicting the reactivity of a rock to carbon dioxide (CO2) and for quantifying mineral carbonation. Lizardite and smectites in kimberlite are reactive to CO2, but they are structurally disordered and cannot be quantified using the standard rietveld approach. In this study, the Partial Or No Known Crystal Structure (PONKCS) method was used to model the peak profiles of smectite and lizardite to account for turbostratic stacking disorder in synthetic samples of processed kimberlite. Lizardite and montmorillonite PONKCS models were made using XRD patterns collected with three X-ray diffractometers: two XRDs from the same manufacturer and of similar model (XRDs B1 and B2) and another XRD from a different manufacturer (XRD A1). Five synthetic samples of processed kimberlite of known compositions were prepared and used to test the results of these PONKCS models for data collected using all three instruments. The results provide a total bias ranging from 4.8-14.1 wt% using correctly calibrated, instrument-specific PONKCS models. We also tested the sensitivity of the PONKCS method to changes in instrument geometry: PONKCS models calibrated for one instrument (XRD B1) were used in refinements with XRD data collected on an instrument made by a different manufacturer (XRD A1), or on a similar instrument made by the same company but having a slightly different geometry (XRD B2). Results were highly inaccurate when PONKCS models calibrated to XRD B1 were used with patterns collected on XRD A1 (32.1-71.6 wt% total bias for our weighed mixtures). Our results show that the smaller differences in instrument parameters between XRD B1 and XRD B2 can also lead to inconsistent and less accurate QPA results using PONKCS (9.8-32.7 wt% total bias). Therefore, correct calibration of PONKCS models to a specific XRD instrument is required for accurate QPA and quantification of CO2 m

关键词： rietveld method mineral carbonation carbon mineralization PONKCS lizardite smectites

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Full-profile search-match by the rietveld method

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JOURNAL OF APPLIED CRYSTALLOGRAPHY 2019年第3期52卷 587-598页

作者： Lutterotti, Luca Pilliere, Henry Fontugne, Christophe Boullay, Philippe Chateigner, Daniel Univ Trento Dipartimento Ingn Ind Trento Italy INEL SAS Thermo Fisher Sci Artenay France Normandie Univ Univ Caen Normandie ENSICAEN CRISMAT Caen France

A new search-match procedure has been developed and tested which, in contrast to previously existing methods, does not use a set of lines identified from a diffraction pattern, but an optimized rietveld fitting on the raw data. Modern computers with multicore processors allow the routine to be fast enough to perform the entire search in a reasonable time using quite large databases of crystal structures. The search-match is done using the crystal structures for all phases and the instrumental geometry, and as such can be applied to every kind of diffraction experiment, including X-rays, thermal/time-of-flight neutrons and electrons. The methodology can also be applied to nanocrystalline samples for which peak identification may be a problem. A web interface has been developed to permit easy testing and evaluation of the procedure. The quality of the results mainly depends on the availability of the sought phase in the structure database. The method permits not only phase identification but also a rapid quantification of the phases and their gross microstructural features, provided the instrumental function is known.

关键词： rietveld method search-match diffraction full profile quantitative analysis

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Physical approach for a quantitative analysis of the phytosterols in free phytosterol-oil blends by X-ray rietveld method

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FOOD RESEARCH INTERNATIONAL 2019年 124卷 2-15页

作者： Gomes Silva, M. Santos, V. S. Fernandes, G. D. Calligaris, G. A. Santana, M. H. A. Cardoso, L. P. Ribeiro, A. P. B. Univ Estadual Campinas Dept Food Technol Sch Food Engn 80 Monteiro Lobato St BR-13083970 Campinas SP Brazil Univ Estadual Campinas Dept Biotechnol Proc Sch Chem Engn 500 Albert Einstein Ave BR-13083970 Campinas SP Brazil Univ Estadual Campinas Inst Phys Gleb Wataghin Dept Appl Phys 777 Sergio Buarque de Holanda St BR-13083859 Campinas SP Brazil

This study investigates and compares the thermal phase transition and crystallization characteristics of a commercial food grade free phytosterol blend (FP) with a stigmasterol analytical standard (SS), the FP behavior in a food model system after its addition to high oleic sunflower oil (HOSO). The properties of the FP:HOSO blends were studied by differential scanning calorimetry, solid content, crystal morphology, and X-ray diffraction (XRD) measurements. The rietveld method (RM) was applied associated with the XRD measurements to support phase analysis and the study of crystallinity degree. The materials were also characterized by means of chemical composition, such as fatty acids and triacylglycerol profiles, for HOSO, and phytosterol profile, for FP. Regarding phase behavior and crystallinity properties, FP has very similar characteristics to SS. The thermal behavior of FP:HOSO blends has two characteristic peaks, one from FP and the other from HOSO. The similarity reported in the literature between the diffraction pattern of FP and pure phytosterols is a positive characteristic for FP. A high FP concentration resulted in high supersaturation and thus the formation of small crystals. The incorporation of HOSO reduced of the large agglomeration of FP crystals and the dispersion crystalline aggregates (spherulites) of FP crystals. The application of RM in FP:HOSO blends to quantify the crystalline and amorphous phases was successfully used. The application has provided the expected value for these phases, according to the same experimental mass ratio of the blends, thereby validating the applicability of this approach in this type of material.

关键词： Lipids Free Phytosterols rietveld method Polymorphism Crystallization Thermal properties

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X-Ray Diffraction Analysis of Ultrasound-Treated Alloy 6061 by rietveld method

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METAL SCIENCE AND HEAT TREATMENT 2019年第9-10期60卷 574-579页

作者： Chen, Fengyuan Tang, Binbin Highway Engn Testing & Evaluat Ctr Qinghai Prov Xining Qinghai Peoples R China Qinghai Univ Sch Mech Engn Xining Qinghai Peoples R China

Aluminum alloy 6061 is studied after an ultrasonic treatment conducted at different vibration amplitudes in the casting process. The alloy is subjected to a diffraction analysis with processing of the spectra by the rietveld method using the MAUD (Materials Analysis Using Diffraction) software. The texture parameters, the rms strain, the lattice parameter, and the crystallite size are determined by the rietveld technique. It is shown that the porosity of the alloy deceases considerably after the ultrasonic treatment, which also affects positively the texture of the alloy.

关键词： aluminum alloy ultrasonic treatment microstructure x-ray diffraction rietveld method

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Microstructural characterization and quantitative phase analysis of Ni-rich NiTi after stress assisted aging for long times using the rietveld method

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MATERIALS CHEMISTRY AND PHYSICS 2020年 241卷 122317-122317页

作者： Naji, Hojjat Khalil-Allafi, Jafar Khalili, Vida Sahand Univ Technol Fac Mat Engn Res Ctr Adv Mat POB *** Tabriz Iran Univ Bonab Fac Engn Dept Mat Engn Bonab Iran

The present work was aimed to quantitatively analyze the phases in the Ni-rich NiTi shape memory alloy which was aged at different temperatures of 470, 500 and 530 degrees C for 11, 38, 196 and 536 h. The aging treatment was done while applying various stress values. The phase transformation behavior of prepared specimens was analyzed using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) at ambient temperature and 75 degrees C. The weight percent of the different phases was measured by the rietveld refinement method using MAUD software. The quantitative phase analysis and transmission electron microscopy (TEM) images show that the amount of Ni4Ti3 precipitates is increased in the specimens aged under stress. Furthermore, the Ni4Ti3 metastable precipitates are transformed to Ni3Ti2 and Ni3Ti stable phases after a long period aging under 120 MPa for 536 h and the various variants of precipitates are not affected by applied stress after long periods of aging.

关键词： NiTi shape memory alloy rietveld method Quantitative phase analysis Ni3Ti precipitates

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Quantitative analysis of crystalline and amorphous phases in pulverized coal fly ash based on the rietveld method

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JOURNAL OF NON-CRYSTALLINE SOLIDS 2018年 483卷 37-42页

作者： Yan, Kezhou Guo, Yanxia Ma, Zhibin Zhao, Zesen Cheng, Fangqin Shanxi Univ Inst Resources & Environm Engn State Environm Protect Key Lab Efficient Resource Taiyuan 030006 Shanxi Peoples R China

High proportions of the amorphous phases with minor and variable amounts of crystalline phases (most commonly mullite and quartz) are the main components of pulverized coal fly ash (PCFA). As for the amorphous phase, it can be further subdivided into amorphous aluminum-silicon matrix (AASM) and amorphous silicon (AS), which show different reaction activity during subsequent applications. In the present work, a more comprehensive approach to evaluate the relative content of crystalline and amorphous phases in PCFA was proposed and verified. The results showed that the AS in PCFA can be removed by sodium hydroxide solution under certain leaching conditions, such as NaOH(aq) concentration ((<)15%) and temperature ((<)80 degrees C). The terminating point of the removal of AS was marked by the forming of hydroxysodalite (Na8Al6Si6O24(OH)(2)(H2O)(2)) in desilicated PCFA (De-PCFA). Based on the rietveld method, the quantitative analysis of crystalline and amorphous phases in PCFA and De-PCFA was performed in turn;then the relative content of crystalline (mullite, quartz) and amorphous (AS, AASM) phases in PCFA can be obtained by calculation.

关键词： Pulverized coal fly ash Alkali leaching Amorphous silicon rietveld method

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