Spectroscopic investigation and simulation of the crystal field effect as well as paramagnetic behavior of K2La1−xPrxCl5 ternary chlorides

A series of potassium lanthanum praseodymium ternary chlorides, K2La1−xPrxCl5, (0.02 ⩽ x ⩽ 0.15) single crystals was grown with Bridgman techniques. The structures of the mixed crystals were found isotypic with that of K2PrCl5 and K2LaCl5. The high resolution absorption, luminescence and excitation spectra were recorded at 4, 77 and 293 K. Broad band emission of Pr3+ reabsorbed by the 3H4 → 3PJ,1D2 transitions was observed simultaneously with the emission from the 3P0 level after excitation in the UV region. The 4f1 5d1 level scheme derived from the absorption, excitation spectra and from VUV synchrotron excitation was partly established. The 4f2 energy level scheme of the Pr3+ ion in K2PrCl5 consisting of 86 (out of 91) Stark components determined from the absorption and emission spectra was simulated by using a phenomenological crystal field model. The model including eight free ion and nine crystal field parameters (according to the C2v symmetry) yielded a rms deviation of 17 cm−1 between the experimental and calculated energy level schemes. Magnetic susceptibility measurements were carried out between 2 and 298 K. Good agreement was obtained between the experimental and calculated paramagnetic susceptibilities as a function of temperature by using the van Vleck formalism and the energies and wave functions derived from the spectral data.