Microscopic analysis of the crystal field strength and electron-vibrational interaction in cubic SrTiO₃doped with Cr³⁺, Mn⁴⁺and Fe⁵⁺ions

Abstract

A detailed microscopic study of the crystal field strength 10Dq for different interionic distances in cubic SrTiO(3) doped with three isoelectronic ions (Cr(3+), Mn(4+) and Fe(5+)) was performed. The exchange charge model of the crystal field was used to calculate the 10Dq values at different distances between impurity ions and ligands. The obtained results were represented by the power laws 1/R(n), with n = 4.9050, 5.7990 and 6.5497 for Cr(3+), Mn(4+) and Fe(5+), respectively. For the first time the role of two different contributions (the point charge and exchange charge) into the total crystal field strength was studied separately. With the obtained 10Dq(R) dependences, a number of important physical quantities describing the optical and dynamical properties of impurity centers (such as the constants of the electron-vibrational interaction, Huang-Rhys parameters, Stokes' shifts, Jahn-Teller stabilization energies, changes of the chemical bond lengths due to the combined effect of the local vibrational normal modes, bulk modulus and Grüneisen constants for the a(1g) normal mode) were calculated. The obtained results are in good agreement with available experimental data and can be readily applied for analysis of the optical spectra, electron-vibrational interaction and pressure effects for these and other similar systems.

Comparative analysis of crystal field effects and energy level scheme of six-fold coordinated Cr4+ ion in the pyrochlores, Y2B2O7 (B=Ti4+, Sn4+)

“…ECM has been successfully applied for the calculations of energy level of rare earth ions ( [14,17,18] and references therein) and transition metal ions ( [19][20][21][22][23] and references therein).…”

Interpretation of the Spectroscopic Properties of α-LiAlO2: Mn4+

“…The 2 E g state in the perovskite SrTiO 3 occurs at very low energy, 13 792 cm −1 (725 nm). 16 In this perovskite, the octahedral groups are perfectly symmetrical: O-Ti-O bond angles are the ideal 90…”

Jahn–Teller effect in 4T2g excited state of Mn2+:MgO

“…A number of works [12][13][14][15][16][17][18][19] employing quantum-mechanical calculations reported the values of n in a rather wide interval from 3.5 to 7.3 , for different systems. This deviations from n = 5 value, predicted by the simple PCM of CF, can be explained by the covalent and exchange effects.…”

“…Knowledge dependence of 10Dq parameter on interionic distance R between Mn 2+ impurity ion and O 2À ligands of [MnO 6 ] 10À cluster, does not only play a key role in the impurity ion energy levels splitting, but can help to estimate the EVI constants, HR parameters and E JT [17].…”