X-ray emission spectroscopic studies of some germanate garnets

Ca3A2Ge3O12 single crystals, where A=Cr, Mn, Fe and Ga, grown by the flux technique and Mn3B2Ge3O12 single crystals, where B=Cr, Fe and Ga, grown by the chemical vapor transport method have been investigated. Measurements have been made on the Kβ1,3 and Kβ5 X-ray emission lines of calcium, chromium, manganese and iron and on the Lα1,2 and Lβ1 lines of gallium and germanium for the garnets and for a few related reference compounds. The presence of Mn²⁺ ions in the Ga3Mn2Ge3O12 crystal was detected by analysis of the multiplet splitting of the 3p shell of manganese. In the same crystal marked deviation from stoichiometry was found. The strong overlap of valence orbitals of cations and oxygen in a few cases was revealed by the observation of a maximum caused by the electronic transition between the 2p shell of oxygen and 1s shells of Ca, Cr and Mn.