Luminescent properties of Eu³⁺ doped layered perovskite-like polycrystalline powders of the BaLa₂₋ₓEuₓTi₃O₁₀ (x = 0-2) titanate compounds

The photoluminescent properties of concentration set of barium and lanthanum titanium compounds doped with europium ions, BaLa₂₋ₓEuₓTi₃O₁₀, where x = 0-2, were investigated. It was found that the luminescence of mentioned materials is caused by ⁵D₀ —> ⁷Fj (J = 0, 1, 2, 3 and 4) radiation transitions in luminescence centers formed by Eu³⁺ ions. Two types of luminescence centers which differ by symmetry of neighborhood of Eu³⁺ ions were found in luminescent emission. It was shown that luminescent characteristics of Eu³⁺ ions are in close relation with their content in BaLa₂₋ₓEuₓTi₃O₁₀ compounds that can be caused by both changing their crystal structure and phase composition when the ratio of La³⁺ and Eu³⁺ ions is changed

Oscillation features of the thermal radiation from a heated crystal plate

The presented results show that the spectrum of thermal radiation from a semiconductor plate whose opposite faces are parallel to each other demonstrates an oscillating character. This is due to the interference effects in the Fabry-Perot resonator. The spectrum features strongly depend not only on the plate thickness, but also on such parameters as plasma frequency (\omega_{\ab{p}}) and damping coefficient (\gamma_{\ab{p}}). The electron-hole plasma frequency can be easily varied by photo-excitation, injection of electrons or holes, and other techniques. So one can hope that the study of thermal radiation from such semiconductor elements would allow developing new efficient and controlled IR radiation sources