[en] For the first time thermoluminescence of Lu₂O₃:Tb,Ta ceramics sintered at 1700 °C in different atmospheres – air, forming gas and vacuum – were investigated. Exposure of the materials into the 254 nm radiation of a mercury lamp led to the Tb³⁺ green persistent luminescence of noticeable intensity. Thermoluminescence glow curves revealed two strong thermoluminescence peaks located around 170 °C and 250 °C, with the former being by a factor of ~2–2.5 more intense compared to the latter. T_max-T_stop thermoluminescence experiments revealed that each of these bands is composed of numerous individual, strongly overlapping components of similar characteristics, known as continuous traps distribution. The highest thermoluminescence was observed from the material sintered in vacuum. Those sintered in air or forming gas showed the storage capabilities by about 15–25% lower, though shapes of their glow curves were very similar. A scheme of carriers trapping was proposed with the hole immobilized at Tb³⁺ site and the electron being trapped in the vicinity Ta(V) impurity due to its strong positive net charge in the Lu site.

[en] Lu₂O₃:Tb,Hf ceramics were investigated as energy storage materials. It was shown that X-rays caused a significant thermoluminescence with a main band around 250 C at a heating rate of 4.8 C s^-1. 780 nm radiation released up to about 75% of the stored energy, while 420 nm light liberated all the stored energy in the form of green photons produced by the Tb³⁺ ions. (orig.)

[en] Photo- thermo- and optically stimulated luminescence properties of Lu₂O₃:Tb,Ta ceramics sintered at 1700 °C in air were investigated. Low temperature (10 K) excitation and emission spectra using synchrotron excitation in the range of 150–330 nm are also discussed. The effect of the dopant contents on the various luminescence effects and processes was tackled. The ceramics showed intense thermoluminescence (TL) and the glow curve consisted of two main peaks around 170 and 250 °C upon 5 °C/s heating rate. The shape of the glow curve and TL intensity depended strongly on the dopant concentrations. Above 0.1% of their contents the TL quickly lessened to disappear around 1%. This was in contrary to photoluminescence which hardly showed any quenching up to the concentration of 1%. In addition to the regular first order TL kinetics some contribution from tunneling and semi-localized transitions was proved.

[en] Lu₂O₃:Tb,Hf ceramics containing 0.1% of Tb and 0-1.5% of Hf were prepared in reducing atmosphere at 1700 ^oC and their thermoluminescence properties were systematically studied. For comparison Tb,Ca co-doped specimen was also fabricated and investigated. The Tb,Hf ceramics shows basically a single TL band located around 180 ^oC as found with heating rate of 15 ^oC/min. Ceramics singly doped with Tb show complex TL glow curves indicating the presence of traps of very different depths. On the other hand Tb,Ca co-doping is beneficial for the development of shallow traps with the main TL band around 70 ^oC. Hence, the aliovalent impurities, Ca²⁺ and Hf⁴⁺, strongly influenced the traps structure in Lu₂O₃:Tb ceramics, each of them in its own specific way. Isothermal decay of Lu₂O₃:Tb,Hf at 185 ^oC was recorded and its shape suggest that multiple hole trapping occurs in the Lu₂O₃:Tb,Hf ceramics. Due to the different traps depths the Lu₂O₃:Tb,Hf ceramics possess properties typical for storage phosphors, while Lu₂O₃:Tb,Ca is a persistent luminescent material rather.

[en] X-ray induced effects in LuPO₄:Eu³⁺ sintered thermoluminescent material were investigated by absorption and photoluminescence measurements between 20 and 300 K. Evidence for Eu³⁺→Eu²⁺ conversion upon exposure to X-rays was obtained as narrow band blue Eu²⁺ photoluminescence was observed. The low temperature luminescence of Eu²⁺ ions in X-rayed LuPO₄:Eu ceramics showed a unique fine structure with a sharp zero-phonon line at 425.8 nm and well-resolved vibronic structure. Excitation spectra of the Eu²⁺ luminescence revealed a rich structure in which individual 4f⁷→ 4f⁶(⁷F_J)5d¹ zero-phonon lines accompanied by vibronic transitions were identified. A detailed analysis allowed an accurate calculation of the Eu³⁺-like 4 f⁶(⁷F_J) core levels in the 4 f⁶5d¹ excited configuration. The 4f⁶ core splitting is different from that of the ⁷F_J states for Eu³⁺ in LuPO₄, providing evidence for the role of 4f⁶–5d interaction on the splitting of the 4f⁶ configuration. The unique luminescence of Eu²⁺ with a small Stokes shift and well-determined energies of 4f⁶(⁷F_J)5d¹ excited states make LuPO₄:Eu a model system for testing theoretical models which are presently developed to calculate and predict the energy level structure and Stokes shift of 4fⁿ–4fⁿ⁻¹5d¹ transitions of lanthanides.

[en] Highlights: • Thermoluminescent properties of Lu₂O₃:Tb,M (M = Hf,Ti,Nb) comprehensively compared. • Linear dose-response dependence exceeding as much as seven orders of magnitude. • Extreme radiation hardness proved. • Self-dose of the radioactive ¹⁷⁶Lu on TL quantitatively studied. Thermoluminescent properties and energy storage characteristics of Lu₂O₃:Tb,M (M = Hf, Ti, Nb) sintered ceramics induced by ionizing radiation are presented and discussed. Dose-response dependence, radiation hardness and fading are studied. A linearity of the former exceeding seven orders of magnitude is confirmed for Lu₂O₃:Tb,Hf and Lu₂O₃:Tb,Nb ceramics. Lu₂O₃:Tb,Hf shows the best TL performance and also its fading is the lowest reaching 15% over 7 h and shows tendency to saturate. During the same period of time the Lu₂O₃:Tb,Ti, despite having TL at higher temperatures, losses about 25% of the stored energy and the TL signal of Lu₂O₃:Tb,Nb fades by almost 40% over 7 h. First order TL kinetics is confirmed for all three compositions. A self-dose effect in Lu₂O₃:Tb,Hf due to a natural content of the radioactive isotope (2.6%) is proved to be important for long-time reading of low doses.

[en] Two types of new Ln³⁺ chelates, phosphoro- and sulfono-derivatives of beta-diketones and Lewis base ligands were obtained and characterized by the high resolution photoluminescence spectroscopy at 293 and 77 as well as by luminescence decay times. The new type of phosphors shows very strong emission after excitation in the UV range within the ligand bands. The dynamics of the excited state will be discussed. The paths of the energy transfer (ET) are analyzed and mechanism of this process is proposed. The silica gels containing investigated complexes with silver particles were obtained and the role of silver plasmons on spectroscopic properties is displayed. - Highlights: • Spectral characteristic of new type of lanthanide chelates: Na[Ln(SP)₄] and [Ln(SP)₃L]. • Preparation of the energy-transfer (E-T) diagram. • Analysis of the possible pathways of energy transfer and their mechanism. • Application of chelates incorporated in sol–gel codoped by Ag particles.