Jahn‐Teller Effect in EPR and Optical Absorption Spectra of Cu²⁺ in LiNbO₃ Single Crystals

Abstract

Optical and E P R spectra of LiNbO, single crystal doped with copper ions are measured in the range of 200 to 6000 nm and in the X-band, respectively. In the temperature range 60 to 200 K a transition is observed from the low-temperature E P R spectra with C, symmetry (gz = 2.403, gn, = 2.121, g, = 2.095 and x^c, = 51") to the high-temperature spectrum with Csv symmetry (g;l = 2.22, g ; = 2.17 and x 11 C,) whose parameters are given by the average of the corresponding parameters of the low-temperature spectra. E P R spectra of LiNbO,: Cu2+ are interpreted taking account of the static Jahn-Teller effect in trigonal field and formation of non-equivalent minima on the adiabatic potential surface. I n case of the static Jahn-Teller effect in trigonal field formulas for the g-factors of d9 ions are derived theoretically. A new model of Cu2+ substitution in LiNbO,, i.e. formation of a CUET-VL~ complex, is suggested. In optical spectra a n absorption band a t 5000 cm-' is detected due to Jahn-Teller splitting of the zEtr ground state. The Jahn-Teller stabilization energy EJT = 1250 cm-l and crystal field parameters 1ODq = 8200 cm-l, w = -1200 cm-l, and w' = 600 cm-l are determined. Tennepa. HpennomeHa HoBaH Monenb a a~e w e~~~ Cu2+ B LiNbO, -06pa30BaHIIe IFOMnJIeKcoB CUiT-VLi. B cneIcTpax OnTLZYecKoro nornoueHHR 06HapyXeHa nonoca Ha TxacToTe 5000 cm-l 06yCfiOBneHHaR FIT pacwennemeM OcHoBHoro YPOBHR 2Eg. Onpeaenemi BH~PTIIFI FIT c~a611n113aq~~ EJT = 1250 cm-l A napaiweTpb1 KpncTannwxecKoro nonrl: 10Dq = 8200 cm-l, TJ = -1200 cm-l, w' = 600 cm-l.

Theoretical explanation of EPR parameters for Cu2+ ion in TiO2 crystal

“…Usually, t 2 ≈ 3 and t 4 ≈ 5 because of the ion nature of the bonds [14]. For the (CuO 6 ) 10− octahedral cluster in LiNbO 3 :Cu 2+ , A 4 (R 0 ) ≈ 615 cm −1 with R 0 ≈ 2.153 Å [15]. Since the ratio A 2 (R 0 )/ A 4 (R 0 ) is in the range of 9 ~ 12 for 3d n ions in many crystals [14,16], we take A 2 (R 0 ) ≈ 12A 4 (R 0 ) here.…”

Investigations of spin‐Hamiltonian parameters and defect structures for two tetragonal Cu2+ centers in KTaO3 crystal

“…where i = // or ⊥ and the other symbols are standard [32][33][34][35][36]. By using the strong field basis functions [40], the complete energy matrix can be established.…”

Theoretical studies of spin Hamiltonian parameters for the tetragonally elongated Cu2+ centers in ARbB4O7 (A = Li, Na, K) glasses

“…For 3d n ions in the octahedral clusters, the relationships Ā 4 (R 0 ) ≈ 3/4D q and the ratio Ā 2 (R 0 )/ Ā 4 (R 0 ) ≈ 12 are proved to be valid in many crystals [10,11,13,18] and reasonably adopted here. Since no optical spectral parameters for ARbB 4 O 7 :Cu 2+ were reported, according to the optical spectra for Cu 2+ in some oxides, and the similar ternary glasses 15MgO-15Na 2 O-69B 2 O 3 (MNB):Cu 2+ with [CuO 6 ] 10− clusters, the value Ā 4 (R 0 ) ≈ 755 cm −1 [19,20] can be obtained and adopted here. In addition, in Eq.…”