SU1647391A1 - Method for determining active oxygen in superconducting copper -containing ceramics - Google Patents

Abstract

The invention relates to methods for determining active oxygen in superconducting copper-containing ceramics and can be used in the development of high-temperature superconductors technology and in controlling their quality in order to improve accuracy and reduce analysis time. To do this, prepare 0.05 n. The invention relates to analytical chemistry, in particular, to methods for determining active oxygen in superconducting copper-containing ceramics, and can be used in the development of high-temperature superconductors technology and their quality control. The aim of the invention is to improve the accuracy and reduce the analysis time. Example. Prepared 0.05 n solution of iron perchlorate (H). To do this, iron perchlorate (It) solution is dissolved in a flask by dissolving a portion of the Mora salt in perchloric acid. A portion of the sample of superconducting ceramics is dissolved in 10 ml of 0.06 n. Fe (CIO / i) 2 solution mixed with NH / iCl4. After the sample is completely dissolved, 10 ml of concentrated HzP04 and 10 ml of HCI04 are added to the solution, 3 drops of diphenylaminosulfonic acid. sodium nitrate and titrated with 0.04 N of the CrSg20t solution. The calculation of the amount of active oxygen is carried out according to the formula X-M a / (2m-16a). where M is the molecular weight of the compound, excluding active oxygen; m is the sample mass G, a is NK2O2O7 (Vl-V2) 10 3, rfleNK2Cr2O7 is normality of potassium bichromate solution, Vi and V2 are the volumes of dichromate solution capi, which are used for titration of 10 ml of ferric chloride solution and test solution, respectively, ml The error in determining the active oxygen index does not exceed 2%; the time taken to perform one measurement is not more than 10 minutes. 1 table sl with sch 0.2 m of barium carbonate (VaSO3) of grade ch.d. and 300 ml of water and pour in small portions of perchloric acid, grade HCSYD grade. (total acid content is 0.5 mol). After the end of the rapid evolution of carbon dioxide, the solution is heated to the beginning of boiling, a solution of Mohr salt (0.1 mol in 200 ml of water) - (NH4) 2Fe (804) 2 grade hp . and allowed to cool. Chlorine solution is filtered. The precipitate is discarded, and the filtrate is about 4 sj CJ h)

Description

diluted in a solution with HCL4 (with an acid content of 2 mol) and adjusted to a volume of 2 liters.

The pH 0 prepared by the solution is transparent, has no color, is practically not oxidized, and is stable for a long time. The exact concentration of the resulting iron (II) perchlorate solution is determined by titration with potassium bichromate in an acidic medium with sodium diphenylamine sulfonate as an indicator.

A sample of the high-temperature superconducting ceramics UV-2CizOb, 5 with a weight of 0.2 g, is dissolved in 10 ml of a solution of Fe (CIO4) 2 in a mixture with MSW. Dissolution occurs without heating for 5 minutes. The ease of dissolution is due to the relatively high acidity of the solution. After the sample is completely dissolved, 10 ml of concentrated Fe3 and 10 ml of HC1Cm, 3 drops of sodium diphenylamine sulfate are added to the solution and titrated with 0.04N. a solution of foCrsC, prepared from an exact weight of salt brand h.ch. Before each determination, the concentration of the Fe (Cl04) 2 solution is monitored.

The calculation of the amount of active oxygen (X) is carried out according to the formula

X

MA

2t - 16a

where M is the molecular weight of the compound excluding active oxygen (for HCa2CizOb, .19), m is the mass of the sample, g;

and NK2Cr20 (Vt - V2) 10 3, where NK2Cr2O7 is the normality of the potassium dichromate solution;

Vi is the volume of potassium dichromate solution, used for titration of 10 ml of ferric chloride solution; ml;

/ 2 - the volume of potassium dichromate solution going to the titration of the test solution, ml.

The volume that went to the titration of 10 ml of a solution of Fe (CI04) 2 and NH4CI04 (after adding 10 ml of NSU4I 10 ml NsRSch) is 3.

The table shows the weights of the sample, the volume of solutions of potassium dichromate, followed by titration of solutions of ferric chloride, in which the weights are dissolved and the calculated index X.

The proposed method allows to determine the active oxygen index with an error of less than 2%, whereas for the prototype this value is not less than 5%. Time spent for carrying out one analysis, no more than 10 minutes, and for a prototype 1-2 hours are necessary because of the considerable duration of sample dissolution.

Claims (1)

Invention Formula A method for determining active oxygen in superconducting copper-containing ceramics, including dissolving a sample in an iron (II) salt solution, introducing concentrated acids, including phosphoric, and the subsequent quantitative registration of the residue of the salt of jedesis (II) by the titrimetric method, characterized in that, in order to improve the accuracy and reduction of the analysis time, iron (II) perchlorate in a mixture with ammonium perchlorate is used as the iron (II) salt, and perchloric acid is added before titration.