THE ANALYSIS OF ZIRCONIUM DIOXIDE STABILIZED WITH YTTRIUM OXIDE BY ATOMIC-EMISSION SPECTROMETRY WITH INDUCTIVELY COUPLED PLASMA

Abstract

A method of aluminum, hafnium, iron, yttrium, calcium, magnesium, and titanium determination in yttria-stabilized zirconia (YSZ) by inductively coupled plasma atomic emission spectrometry (ICP-AES) is described. Conditions for the decomposition of two modifications of the analyzed material — unburned and subjected to stabilizing firing — were studied. It was found that the unburnt zirconia dissolves well in sulfuric acid, and the conversion to the solution of the burnt sample is possible only with fusion with potassium pyrosulfate or potassium bifluoride, but using of these reagents leads to high values of the control experiment correction for trace impurities (at the level of tenths and hundredths of a percent). In this connection, we studied the possibility of acid dissolution of a burnt sample under microwave decomposition, varying the qualitative and quantitative composition of the acid mixture, the reaction temperature, the time to reach and to maintain the required temperature. It was found that the decomposition in the mixture of hydrofluoric and sulfuric acids (2:1) in the microwave system with stepwise heating of the reaction mixture ensures quantitative dissolution of the burnt sample and sufficiently low values of the control experiment correction for microimpurities. The analytical lines were chosen taking into account their relative intensity, possible spectral overlaps, and the matrix effect in the analysis of model solutions containing 1.3 mg/cm 3 Zr, 0.2 mg/cm 3 Y and from 0.2 to 20 mg/cm 3 impurities. As a result, the following analytical lines were chosen: Al II 167.079 nm and Al I 308.215 nm; Ca II 184.006 nm and 393.366 nm; Fe II 238.204 nm; Mg II 279.553 nm, Ti II 334.941 nm, Y II 371.030 nm and Hf II 232.247 nm. The developed method for the analysis of yttria-stabilized zirconia (YSZ) by the ICP-AES allows simultaneously determining aluminum, iron, magnesium and titanium in the range of 0.01 – 1.0%, calcium — 0.02 – 1.0%, hafnium — 0.1 – 5.0% and yttrium — 2.0 – 15% with a % rel. (Y). The correctness of the method is confirmed by the standard addition technique.