Quantitative determination of rutile versus anatase in heavy minerals by both calibration and Rietveld refinement

Significance of the Topic

Rutile and anatase, polymorphs of titanium dioxide, present distinct physical and chemical properties impacting applications in pigments, semiconductors, and catalysis. Accurate phase quantification ensures optimized performance and quality control in industries reliant on TiO2 materials.

Objectives and Study Overview

This study aims to develop and compare quantitative methods for determining rutile vs. anatase concentrations in mixed mineral samples using calibration curves and Rietveld refinement. Measurements were performed on two Thermo Scientific ARL EQUINOX XRD systems to establish detection limits and accuracy for routine and field-deployable analysis.

Methodology and Instrumentation

• Instrumentation Used: Thermo Scientific ARL EQUINOX 100 and ARL EQUINOX 1000 benchtop X-ray diffractometers equipped with Cu Kα micro-focus tubes and mirror or HOPG monochromators.
• Measurement Conditions: Reflection geometry, 10–20 minutes acquisition times, real-time data collection with curved position sensitive detectors.
• Software Tools: MDI JADE 2010 with ICDD PDF4+ database for calibration curves, MAUD for Rietveld refinement, and MATCH! for qualitative phase analysis.

Results and Discussion

Calibration curves derived from peak intensity ratios show strong linearity, with both instruments quantifying anatase above 1.5 wt % reliably. The higher-powered EQUINOX 1000 extends the detection limit to 0.8 wt % anatase. Rietveld refinement confirms accuracy within 0.1 wt % of reference compositions, demonstrating robust agreement between measured and theoretical values.

Benefits and Practical Applications

• Simplicity: Calibration curve approach allows inexperienced users to obtain reproducible results in production environments.
• Portability: Low-maintenance benchtop design enables deployment from laboratory to field without external cooling systems.
• Efficiency: Rapid data acquisition and real-time analysis reduce downtime and enhance throughput in QA/QC workflows.

Future Trends and Potential Applications

Anticipated developments include integration of automated sample handling, enhanced detectors for lower detection limits, and machine learning algorithms to streamline phase quantification. Expanding to other polymorphic systems and in situ monitoring could further broaden applicability across materials science and environmental analysis.

Conclusion

The ARL EQUINOX 100 and 1000 XRD systems, in combination with calibration and Rietveld refinement methods, provide reliable, user-friendly solutions for quantifying rutile and anatase in heavy mineral samples. Their performance supports both routine quality control and field analysis, offering accurate phase determination down to sub-percent levels.

Instrumentation Used

• ARL EQUINOX 100 X-ray diffractometer with Cu micro-focus tube and curved position sensitive detector.
• ARL EQUINOX 1000 X-ray diffractometer with high-power generator, HOPG monochromator, and curved position sensitive detector.