The same chemical stability that makes Cr₂O₃ immortal in refractories makes it invaluable in electronics — provided the sodium stays out. Our EG-series is washed, refined and controlled to ppm-level alkalis for MLCC ceramics, sputtering targets and varistors.
Two purity tiers for one job: keeping mobile ions out of your dielectric. Choose EG-99 for volume electronic-ceramic work; EG-99H where the datasheet says ppm.
| SPECIFICATION | EG-99 | EG-99H |
|---|---|---|
| Cr₂O₃ | ≥ 99.2 % | ≥ 99.5 % |
| Sodium (Na₂O) | ≤ 100 ppm | ≤ 50 ppm |
| Iron (Fe) | ≤ 200 ppm | ≤ 100 ppm |
| Calcium + Magnesium (CaO + MgO) | ≤ 150 ppm | ≤ 80 ppm |
| Magnetic impurities | ≤ 10 ppm | ≤ 5 ppm |
| Particle size D50 | 0.6–1.5 μm | 0.3–0.8 μm |
| Loss on ignition (1000 °C) | ≤ 0.2 % | ≤ 0.15 % |
| Cr(VI) | Not detected | Not detected |
| Specific surface area (BET) | 3–8 m²/g | 5–12 m²/g |
| Tap density | 2.4–3.0 g/cm³ | 2.0–2.6 g/cm³ |
| Bulk density | 1.1–1.4 g/cm³ | 0.9–1.2 g/cm³ |
| Particle span D10–D90 | 0.2–3.0 μm | 0.1–1.8 μm |
Sodium gets the headlines — but it is not alone. Eight properties decide whether electronic-grade Cr₂O₃ performs in your component. Every one of them is controlled at the ppm scale.
Na⁺ drifts through BaTiO₃ grain boundaries under DC bias, degrading insulation resistance over the capacitor’s life. The only cure is ppm-level sodium at the raw-material stage.
Alkali contamination accelerates the aging of capacitance and tan δ. Electronic-ceramic producers pay for low sodium because field failures are far more expensive than ppm.
Alkali metals in a sputtering target become vapor-phase impurities in the film. A ≤50 ppm Na₂O feed powder is the first gate in a clean-room supply chain.
Ferromagnetic particles (Fe, Ni, Co) create short-circuit paths through thin dielectric layers and arc on sputtering targets. EG-99H holds iron ≤100 ppm and magnetics ≤5 ppm.
CaO and MgO shift grain-boundary chemistry and sintering behaviour — a drift the furnace sees as density and shrinkage variation. ppm control keeps every lot on the same firing curve.
Residual anions from processing attack base-metal electrodes during co-firing and upset paste rheology. Electronic-grade washing drives them below detection.
D50 alone is not enough — a tight D10–D90 span and controlled BET surface area decide how uniformly Cr₂O₃ disperses into BaTiO₃. Uniformity is what the dielectric sees.
Volatiles and adsorbed water become pores and gas defects at sintering. Loss on ignition ≤0.15 % on EG-99H means the furnace fires clean every time.
Where ppm-grade Cr₂O₃ earns its keep — five established roles across the component chain.
Cr₂O₃ is a classic acceptor dopant for BaTiO₃-based multilayer ceramic capacitors. Chromium on the titanium site suppresses reduction under base-metal-electrode firing, keeps insulation resistance high, and improves DC-bias lifetime.
High-purity Cr₂O₃ is hot-pressed or sintered into targets for wear-resistant and optically selective coatings — cutting tools, solar absorbers, decorative films. Powder purity maps directly onto film purity.
In the Bi₂O₃–Sb₂O₃–MnO–Cr₂O₃ system, chromium sits in the grain-boundary barrier — sharpening the non-linear I-V knee and stabilizing the varistor against electrical aging in surge protectors.
Resistor and electrode pastes use fine Cr₂O₃ to tune the glass phase — matching thermal expansion to the substrate and setting the sintering window of the fired film.
Chromium doping tailors the temperature coefficient and loss of piezoelectric ceramics and PTC thermistors — small additions, large effects on the batch.
Plasma-sprayed Cr₂O₃ coatings protect anilox rolls, pump seals and printing machinery. The electronic grade adds chemical tightness to a mechanical coating.
Deep dives written around the EG-series — the chemistry, the specs, and how to buy electronic-grade Cr₂O₃.
Tell us your application, purity target and sodium ceiling — we reply within one working day with grade, D50 and price.
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