Thermal expansion and luminescent properties of triorthogermanates CaLa$_{2-x}$Eu$_{x}$Ge$_{3}$O$_{10}$ ($x$ = 0.0–0.6)

Solid solutions CaLa$_{2-x}$Eu$_{x}$Ge$_{3}$O$_{10}$ ($x$ = 0.0–0.6, $\Delta x$ = 0.1) have been synthesized for the first time. The compounds are isostructural to CaLa$_{2}$Ge$_{3}$O$_{10}$, they crystallize in the monoclinic system, space group $P 2_1/c$, $Z$ = 4. The low-temperature X-ray diffraction studies have revealed the strain anisotropy of germanate CaLa$_{2}$Ge$_{3}$O$_{10}$ crystal lattice in the temperature range 80–298 K, and the linear thermal expansion coefficients have been calculated. The optical properties of the activated phases have been studied, and the influence of the dopant concentration and the excitation wavelength on the luminescence characteristics of the synthesized compounds has been established.