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V5+-Induced Crystal Field Modulation in Mn5+-Rich Ba3Mn2O8 for High-Purity Green Pigments
Manami Tanaka1, Yasuhiro Niwa2,3, Mizuki Watanabe1
1Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-nocho, Niigata 950-2181, Japan.
Inorganic Chemistry
|February 4, 2026
Summary
This study introduces a novel green pigment, Ba3Mn2(1-x)V2xO8, synthesized via solid-state reaction. Diluting manganese with vanadium creates a high-purity green hue with superior stability for next-generation applications.
Area of Science:
- Materials Science
- Inorganic Chemistry
- Solid-State Chemistry
Background:
- Traditional green pigments like chromium(III) oxide (Cr2O3) face environmental and performance limitations.
- Developing novel, high-performance, and stable green pigments is crucial for various industrial applications.
Purpose of the Study:
- To synthesize and characterize novel Ba3Mn2(1-x)V2xO8 pigments.
- To investigate the effect of vanadium(V) doping on the color properties and stability of Ba3Mn2O8.
- To evaluate the potential of these new pigments as alternatives to existing commercial green pigments.
Main Methods:
- Solid-state reaction method for pigment synthesis.
- X-ray diffraction (XRD) for phase analysis and Rietveld refinement.
- UV-Vis spectroscopy for optical absorption analysis.
- X-ray absorption near-edge structure (XANES) spectroscopy to confirm valence states.
- Extended X-ray absorption fine structure (EXAFS) analysis for structural insights.
- Colorimetric measurements (a*, h°) to quantify hue and purity.
Main Results:
- Single-phase rhombohedral Ba3Mn2(1-x)V2xO8 (0 ≤ x ≤ 0.25) pigments were successfully synthesized.
- Vanadium(V) doping into the Ba3Mn2O8 host resulted in a high-purity green color.
- The optimized pigment, Ba3Mn1.6V0.4O8, exhibited superior greenness (-a* = -31.1, h° = 179.9) compared to Cr2O3.
- XANES and EXAFS confirmed the persistence of Mn5+ and revealed a decrease in Mn-O bond length, causing a blue shift in absorption.
- The pigment demonstrated excellent thermal, humidity, and chemical stability.
Conclusions:
- Dilution of Mn5+ with V5+ in Ba3Mn2O8 is an effective strategy for achieving high-purity green pigments.
- The observed color enhancement is attributed to crystal field modulation and structural changes (reduced Mn-O bond length).
- The synthesized Ba3Mn1.6V0.4O8 pigment shows significant potential as a next-generation, high-performance green colorant.
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