Paramagnetism of caesium titanium alum

Abstract

Articles you may be interested in Ab initio study of dynamical E × e Jahn-Teller and spin-orbit coupling effects in the transition-metal trifluorides TiF3, CrF3, and NiF3 J. Chem. Phys. 136, 084308 (2012) Caesium titanium alum, CsTi͑SO 4 ͒ 2 •12H 2 O, is a ␤ alum and exhibits a large trigonal field and a dynamic Jahn-Teller effect. Exact calculations of the linear 2 T 2 e Jahn-Teller coupling show that in the strict S 6 site symmetry the ground multiplet consists of a Kramers doublet 2⌫ 6 with magnetic splitting factors g ʈ ϭ1.1 and g Ќ ϭ0, a ⌫ 4 ⌫ 5 doublet at ϳ60 cm Ϫ1 with g ʈ ϭ2.51 and g Ќ ϭ0.06 and another ⌫ 4 ⌫ 5 doublet at ϳ270 cm Ϫ1 with g ʈ ϭ1.67 and g Ќ ϭ1.83. The controversial g values observed below 4.2 K, g ʈ ϭ1.25 and g Ќ ϭ1.14, are shown to arise from low symmetry distortions. These distortions couple the vibronic levels and induce into the ground state the off-diagonal axial Zeeman interaction that exists between the first excited and the ground vibronic levels. © 1997 American Institute of Physics. ͓S0021-9606͑97͒01804-7͔

The study of the influence of Jahn-Teller coupling and low symmetry strain on the anomalous electron paramagnetic resonance spectrum of titanium(III) doped CsAl(SO4)2⋅12H2O

“…The interpretation of the anomalous EPR spectrum of titanium͑III͒ doped CsAl͑SO 4 ͒ 2 •12H 2 O ͑Cs͓Al:Ti͔SH͒ has been one of the most contentious topics in the theory of the electronic structure of transition metal ions, with numerous models posited. [1][2][3][4][5][6] The titanium͑III͒ ion substitutes for alu-minum͑III͒, which lies on a site of trigonal (S 6 ) symmetry in a cubic ( Pa3) lattice, with the threefold axes of the tervalent cations directed along the ͓111͔ directions of the crystal. The spectrum obtained for each titanium͑III͒ site consists of a number of lines as first reported by Woonton and MacKinnon.…”

“…7 However, this rather fantastic explanation has subsequently been rejected as untenable, on the basis of the relative magnitudes of the ligand field and Jahn-Teller interactions implied. 5,6,8 There is now overwhelming evidence to suggest that the trigonal field is very large, and of a sign such that the orbital doublet lies below the orbital singlet. 9,10 The resulting 2 E g ground term is subject to Jahn-Teller and spin-orbit coupling and a delicate balance between these two interactions has shown to be responsible for the anomalous magnetic properties of CsTi͑SO 4 ͒ 2 •12H 2 O and its magnetically dilute analogs.…”

The dynamic Jahn–Teller effect applied to the temperature-dependent paramagnetic susceptibilities of Ti3+:Al2O3

“…Halliburton et al 10 detected an ESR signal at low temperatures that has been tentatively assigned to Ti 3ϩ pairs in Al 2 O 3 . The results of these measurements and calculations suggest a smaller spin-orbit, a smaller diagonal trigonal field, and smaller Jahn-Teller effect than those used by MacFarlane et al 4 Dubicki et al 12 have also extended the dynamic Jahn-Teller to matrix diagonalization with particular attention to the Ti 3ϩ alums. The results of these measurements and calculations suggest a smaller spin-orbit, a smaller diagonal trigonal field, and smaller Jahn-Teller effect than those used by MacFarlane et al 4 Dubicki et al 12 have also extended the dynamic Jahn-Teller to matrix diagonalization with particular attention to the Ti 3ϩ alums.…”

“…In other models it was necessary to introduce excessive orbital reduction along with a very large trigonal field. The Jahn-Teller calculations of the g factors, Van Vleck susceptibilities, and energies use the perturbation results of Dubicki et al 12 for the magnetic terms with the correction of three terms in their Table II. We selected a range in x, where E JT ϭxប/3, to determine the trigonal field parameters v and vЈ.…”

“…The Jahn-Teller analysis gives very good magnetic constants and a spin-orbit constant but not a unique vibration integral parameter, x, nor crystal field parameters. 18 The calculation of the energy levels for 2 T 2 includes the trigonal field and spin-orbit interaction with the upper 2 E. Further, the work of Dubicki et al 12 indicates that the perturbation approach that we use should be accurate enough for the size of our diagonal trigonal field parameter v. A comparison of the empirical quantities and Jahn-Teller calculated quantities is given in Table I. The orbital reduction factor k was determined from g ʈ 0 ϭ1.067.…”