Vaporization thermodynamics of In O by Knudsen effusion mass spectrometry. The standard enthalpy of formation of In O(g).

RATIONALE

In O is one of the most important semiconductor oxides in modern electronics. Vacuum deposition methods are often used for the preparation of In O -based nanomaterials. Thus, vaporization thermodynamics is of key importance for process control and optimization. Since the literature data on the vapor composition and partial pressure values for In O are contradictory, vaporization thermodynamics of In O needs to be clarified.

METHODS

Vaporization behavior of In O was studied using the Knudsen effusion technique in the temperature range 1400-1610 K. Quartz effusion cells were employed. A magnet mass spectrometer with an ordinary focus and a sector-type analyzer was used. Heating of samples and molecular beam ionization were performed by electron impact. The operating ionizing electron energy was 75 eV.

RESULTS

A specially designed experiment allowed us to determine the individual mass spectrum of the In O molecule and, thus, to interpret the mass spectrum of the vapor registered during In O vaporization. The composition of the equilibrium vapor was quantified and the partial pressures of the vapor species were determined. On the basis of the experimental data, the standard enthalpies of some gaseous and heterogeneous reactions taking place during In O vaporization and the standard enthalpy of formation of In O(g) were calculated.

CONCLUSIONS

The presence of In species in the vapor over In O was confirmed and the vapor composition was quantified. Thermodynamic characteristics of In O vaporization were obtained and a value of the standard enthalpy of formation of In O(g) was recommended. These data can be used for further thermodynamic calculations and for evaluating parameters for the synthesis and exploitation of In O -containing materials.