In perovskite oxides, the activation energy of the first ionization of oxygen vacancies as expressed in Eq. 4 was reported to be 0.1 eV [23 25] and the second ionization of oxygen vacancies [as described in Eq. 5 to the conduction band, the activation energy for conduction was demonstrated to be around 0.7 eV [23, 26].
In their work, at room temperature, the obtained activation energy corresponding to the first ionization of oxygen vacancies of 0.093 eV is responsible for the low-resistance states, while at high-resistance state, the conducting electrons are dominated by the second ionization of oxygen vacancies with the activation energy of 0.63 eV.
We propose that, at room temperature, the first ionization of oxygen vacancies is responsible for the conduction of low-resistance state, while at high-resistance state, the conducting electrons at room temperature are dominated by the second ionization of oxygen vacancies.
At room temperature, the higher E a for the second ionization of oxygen vacancies compared to that for the first ionization indicates that it is more difficult to activate the conducting electrons without any applied field, and hence, the low free-electron concentration is in agreement with the high-resistance state at which the initial samples were set.
The high Ti2 + ion flux is primarily due to the second ionization potential (IP2) of Ti being lower than the first IP (IP1) of Ar.
For magnesium again, the first two molar ionization energies of magnesium given above correspond to removing the two 3s electrons, and the third ionization energy is a much larger 7730 kJ/mol, for the removal of a 2p electron from the very stable neon-like configuration of Mg2+.
The second ionization takes place to an extent of about 25 percent, but HSO4− is nonetheless considered a moderately strong acid.
The first ionization energy is the energy it takes to remove one electron from an atom, the second ionization energy is the energy it takes to remove a second electron from the atom, and so on.
Thus, the +1 oxidation state should be favored, like Tl+, and consistent with this the first ionization potential of ununpentium should be around 5.58 eV, continuing the trend towards lower ionization potentials down the pnictogens.
