Doping of Lanthanum(III) Orthoborates and Metaborates with Europium(III) and Yttrium(III) Ions

Orthoborates La0.95 -xEu0.05YxBO3 and metaborates La0.95 -xEu0.05Yx(BO2)(3) (x = 0.025; 0.05; 0.075; 0.1; 0.2; 0.4; 0.6; 0.8; 0.95) are synthesized under optimal conditions by the extraction pyrolytic method at a lower temperature and a shorter time as compared to the known methods. In single-phase systems, the unit cell volume in La(0.95 -x)Eu(0.05)YxBO(3) (aragonite structural type) and La0.95 -xEu0.05Yx(BO2)(3) (alpha-type monoclinic polymorph) decreases with an increase in the Y3+ ion content. Under excitation at an Eu3+ ion luminescence maximum lambda(em) = 615 nm, the compounds have similar luminescence excitation spectra in the region of 230-320 nm. An increase in the Y3+ ion content (x >= 0.1) in both orthoborates La0.95 -xEu0.05YxBO3 and metaborates La0.95 -xEu0.05Yx(BO2)(3) leads to a certain change in the location and intensity distribution of transition bands because the nearest environment of the Eu3+ ion in these compounds is transformed upon transition from one structural type to another. The introduction of the Y3+ ion into La0.95Eu0.05BO3 (5 mol %) or La0.95-xEu0.05(BO2)(3) (10 mol %) leads to an increase in the integral luminescence intensity. A further increase in the Y3+ ion content decreases the luminescence intensity.