Capacitor powder

Abstract

Disclosed herein are capacitors having an anode based on niobium and a barrier layer based on niobium pentoxide, at least the barrier layer having a content of vanadium and process for their preparation and use.

1 - 11 . (canceled)  
   
   
       12 . Anode based on niobium containing from 10 to 100,000 ppm vanadium.  
   
   
       13 . (canceled)  
   
   
       14 . Anode based on niobium and/or niobium compounds, containing a surface coating of from 10 to 10,000 ppm vanadium, based on the anode.  
   
   
       15 . Powder based on niobium containing from 10 to 100,000 ppm vanadium.  
   
   
       16 . Powder based on niobium containing from 500 to 10,000 ppm vanadium.  
   
   
       17 . Process for the preparation of vanadium-containing powders based on niobium, comprising mixing vanadium powder, vanadium oxide, and/or a vanadium compound that can be decomposed by hydrolysis or thermally to vanadium oxide with a niobium metal, a niobium oxide and/or niobium oxide hydrate, optionally drying and calcining the mixture, and reducing the resulting vanadium-containing mixed oxide to the vanadium-containing niobium suboxide or niobium metal, which is optionally nitridated.  
   
   
       18 . Process according to  claim 17 , wherein the reduction of the vanadium-containing mixed oxide to the vanadium-containing NbO 2  is carried out in a stream of hydrogen at a temperature of from 1000 to 1500° C.  
   
   
       19 . Process according to  claim 17 , wherein the reaction of the vanadium-containing Nb 2 O 5  or NbO 2  with niobium powder, optionally containing vanadium, to vanadium-containing NbO is carried out by heating in a stream of hydrogen or in vacuo at from 900 to 1600° C.  
   
   
       20 . Process according to  claim 17 , wherein the reduction of the vanadium-containing niobium oxide to the niobium metal is carried out by heating in the presence of magnesium vapour under a protecting gas atmosphere.  
   
   
       21 . Process according to  claim 17 , wherein the nitridation is carried out by heating the vanadium-containing niobium metal or niobium suboxide powder in a nitrogen-containing atmosphere.