Vibrational spectra of tetrametagermanates of the type Ln2CuGe4O12 (Ln=lanthanide or Y)

Upconversion luminescence in Er3+/Yb3+ codoped Y2CaGe4O12

“…in-phase vibrations inside the cycle which result in the appearance of collective vibration modes, have been also reported in Ref. [26]. The strongest Raman lines in the 100-1000 cm −1 range are attributed to the totally symmetric vibrations.…”

Synthesis and structural study of a new group of trigermanates, CaRE2Ge3O10(RE = La–Yb)

“…46,47 Moreover, the Ge 3 O 10 group can be considered as a Ge 2 O 7 pyrogroup connected with an additional GeO 3 unit. The latter bears an analogy to ring vibrations in cyclotetragermanates.…”

“…The most intensive Raman lines at 841; 833, 854; 843, 867; 845, 870; 849, 873 cm −1 in the spectra of CaLa 2 Ge 3 O 10 , CaNd 2 Ge 3 O 10 , CaGd 2 Ge 3 O 10 , CaTb 2 Ge 3 O 10 and CaY 2 Ge 3 O 10 , respectively, and infrared bands with the middle intensity around 800-860 cm −1 IJCaRE 2 Ge 3 O 10 ; RE = Y, La-Yb) can be assigned to the ν s IJGeO 3 ) modes. 46,47,53 However, only some of the vibrational bands in the high wavenumber interval in the spectra of CaRE 2 Ge 3 O 10 (RE = Gd-Yb) meet this tendency. In the vibrational spectra of many isostructural series of lanthanide-containing antimonites, arsenates, germanates, phosphates and others, the bands are slightly displaced to higher wavenumbers with unit cell dimensions decreasing due to the phenomenon of lanthanide contraction.…”

Luminescence in Ln2CaGe4O12 under infrared laser excitation

“…When such a system is excited, the former type makes the main contribution to inelastic scattering of the exciting electromagnetic radiation [3,4]. In this process, the heavy cationic sublattice behaves as a reservoir for energy dissipation upon the relaxation of a polyatomic anionic group from the excited to the ground state.…”