Inorganic compounds
View Patent ↗Disclosed is a niobium suboxide powder for the manufacture of capacitors with higher break down voltages, higher temperatures of operation and elongated lifetimes. The powder is doped with nitrogen which is at least partly present in the form homogeneously distributed, x-ray detectable Nb 2 N-crystal domains. The niobium suboxide powder contains niobium suboxide particles having a bulk nitrogen content of between 500 to 20,000 ppm.
1. A niobium suboxide powder comprising niobium suboxide particles having a bulk nitrogen content of between 1,000 to 8,000 ppm, wherein the nitrogen is quasi homogeneously distributed in the bulk of the powder particles and the content of Fe, Cr, Ni, Cu, Na, K, Cl are less than 15 ppm each and wherein the nitrogen at least partly is present in the form of Nb 2 N crystals and the Nb 2 N crystals have a size sufficiently to give a peak in Cu Kα -x-ray radiation at 2Θ-angle of about 38.5°.
2. The niobium suboxide powder according to claim 1 , wherein the nitrogen content is between 3,000 to 5,000 ppm.
3. The niobium suboxide powder according to claim 1 , wherein the height of the Nb 2 N peak at about 2Θ=38.5° is between 2 to 25% of the height of the NbO peak at 2Θ=30°.
4. The niobium suboxide powder according to claim 1 , wherein the Cu Kα1 -peak at about 2Θ=38.5° has a half-value width of between 0.05 and 0.2°.
5. The niobium suboxide powder according to claim 1 , wherein the powder has a grain size distribution characterized by a D10-value of between 50 and 90 μm, a D50-value of between 150 and 210 μm, and a D90-value of between 250 to 350 μm, as determined according to ASTM B 822.
6. The niobium suboxide powder according to claim 1 , wherein the niobium suboxide powder particles are agglomerates of primary particles of mean diameter of 0.1 to 1.5 μm.
7. The niobium suboxide powder according to claim 1 , wherein the niobium suboxide powder particles are agglomerates of primary particles of mean diameter of 0.3 to 1.0 μm.
8. The niobium suboxide powder according to claim 1 , wherein the niobium suboxide has the composition NbO x with 0.7<x<1.3.
9. The niobium suboxide powder according to claim 8 , wherein 1<x<1.033.
10. The niobium suboxide powder according to claim 1 , wherein the oxygen content is between 14.5 to 15.1 wt-%.
11. The niobium suboxide powder according to claim 1 , having a burning time of more than 5 min, when 50 g thereof are arranged in an area of 150×30 mm on a niobium sheet of 0.1 mm thickness and ignited at one end.
12. A niobium suboxide powder comprising niobium suboxide particles having a bulk nitrogen content of between 1,000 to 8,000 ppm, wherein the nitrogen is quasi homogeneously distributed in the bulk of the powder particles and the content of Fe, Cr, Ni, Cu, Na, K, Cl are less than 15 ppm each the nitrogen at least partly is present in the form of Nb 2 N crystals wherein the height of the Nb 2 N peak at about 2Θ=38.5° is between 2 to 25% of the height of the NbO peak at 2Θ=30°.