"One of the bottlenecks of the production of oxide-semiconductor capacitors is enough fast aging of impregnating solutions of manganese nitrate used to form the cathode electrode of manganese dioxide. This effect is caused by the formation and accumulation of impurities of oxides and nitrides of manganese in the solution, which leads to a poor-quality cathode coating of manganese dioxide on the tantalum anode and as a result, poor performance capacitors. Fast aging of impregnating solutions of the Mn(NO3)2 solutions leads not only to an increase in the cost of materials, but also significantly increases of the volume of waste. As a solution to this problem in the proposed article discusses aspects of chemical regeneration of contaminated solutions of manganese nitrate, analyzed the possible ways of its realization in relation to the existing production of oxide-semiconductor capacitors."

Keywords: Manganese nitrate, manganese oxides, cathode coating, impregnating solutions, manganese nitrides, manganese oxohydroxide, chemical regeneration.

In the work presented for the first time experimental data on measurement of the ESR and impedance of a coating of manganese dioxide obtained from manganese nitrate with the addition of silver nitrate by thermolysis method. Analysis of coating (XRF, SEM, XRD) of manganese dioxide with the addition of silver show a significant decrease in the resistance of the coatings. The development of energy efficient coating of manganese dioxide is one of the key objectives in the technology of low-impedance tantalum capacitors. Obtained by thermolytic method (the processing temperature of 250 and 300 °C) coating of manganese dioxide with the addition of silver nitrate 27% solution of manganese nitrate was analyzed using the RLC. The results of studies on the effect of additives in the impregnation solution of manganese nitrate on the resistance of coatings of manganese dioxide showed the possibility of significant reduction of the resistance (15 times at a temperature of thermolysis at 250°C, 45 times at a temperature of thermolysis 300 °C) by reference to the precursor silver nitrate; raising the temperature of the thermolysis of manganese nitrate from 250 to 300°C leads to the decrease of the resistance of the coating; use freshly prepared solution of manganese nitrate leads to the decrease of the resistance of the coating.

Keywords:  manganese nitrate, silver nitrate, manganese oxide, alloying, resistance, thermolysis

Pourbaix diagram data of manganese nitrate dissociation in aqueous solutions at 100, 250 С. The data for the study of manganese oxides phase stability at various conditions such as pH, temperature, partial pressure of oxygen, nitrogen oxide, water vapor are shown. Phase stability diagrams allow to show the influence of partial pressure of a particular gases which are introduced into the reaction zone on phase equilibrium of system and determine termination products of the reaction at different conditions. Phase diagrams of manganese compounds and thermodynamic models of manganese nitrate degradation products are plotted.

Keywords: manganese nitrate, manganese oxide (IV), redox reactions, Pourbaix diagrams, phase stability diagram

In the article obtaining of cathodic coating MnO2 on condenser porous tantalum anode was researched. It was ascertained that formation of crystalline defects from hydrated MnO2 on MnO2 coating obtaining by known technology is possible. Such formations disturb tantalum capacitor cathode integrity. To determine the reasons of the crystal defects formation conveyed simultaneous thermal analysis of Mn(NO3)2x4H2O and Mn(NO3)2x6H2O with an analysis of the flue gases by FTIR spectroscopy. Based on the analysis results a mechanism of manganese nitrate thermolysis was suggested and the cause of the crystal defects on the surface after the coating of manganese dioxide removed from the furnace was ascertained. It was established that the thermolysis process is followed by the formation of such manganese nitrate intermediates as manganese hydroxynitrate, manganese oxyhydroxide and its further oxidation to manganese dioxide. Because of secondary processes leaking on the MnO­2 cover manganese oxyhydroxide residual can react with water vapor and oxygen, that leads to the formation of crystalline defects. Such phenomenon has a negative impact on the chemical composition and integrity of the coating on the surface of the porous MnO2 tantalum capacitor anode. Also it has been found experimentally that manganese hydroxynitrate is formed from manganese nitrate in the form of microtubules on the porous tantalum vehicle surface.

Keywords: manganese dioxide, coating, manganese nitrate, thermolysis, crystalline defects, microtubules

The influence of manganese nitrate impregnating solutions concentration and temperature dynamic viscosity, the wetting angle, interface “porous tantalum electrode - solution” free surface energy and the impregnation degree of porous tantalum anode was researched. A quantitative characteristic of manganese nitrate solution application on porous tantalum anode of solid-electrolyte capacitor during the process of impregnation was defined and work of adhesion and cohesion was calculated. Thus increasing of solution concentration above 42% wt brings to sharp growth of surface tension and so work of cohesion is increased but carriers impregnation is fallen. The most effective impregnation is realized at concentration 27% wt. This fact corresponds to best value of tantalum anode capacitor free surface energy. So using received data we are able to estimate optimal conditions of impregnation and wetting process by nitrate magnesium.  

Keywords: manganese nitrate, manganese dioxide, limiting wetting angle, free surface energy