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Still unsolved is the problem of monitoring the tissue regeneration with the use of implants (substrates) in in vivo conditions. The multitude of implant materials combined with their specific immanent often limit standard diagnostic methods, i.e. X-rey or computer tomography (CT). This is particularly difficult in therapies using polymeric high-resistance substrates for tissue engineering. The aim of this study was to fabricate a non-woven carbon fiber composed of carbon fibers (CF) which were then subjected to a surface modification by magnetron sputtering. A layer of iron (Fe) was applied under inert conditions (argon) for different time periods (2-10 min). It was shown that already after 2-4 minutes of iron sputtering, the voxel surface (CF_Fe2', CF_Fe4') was covered with a heterogeneous iron layer observed by scanning electron microscope (SEM) with energy dispersive X-ray analysis (EDS). The longer the modification time, the more uniform the layer on the fiber surface becomes. This can be seen by the change in the wettability of the nonwoven surface which decreases from 131° for CF_Fe2 to 120° for CF_Fe10. The fibers do not change their geometry or dimensions (~11.5 um). The determination of pore size distribution by adsorption and desorption techniques (BJH) and specific surface area by nitrogen adsorption method (BET) have shown that the high specific surface area for the CF_Fe2' fibers decreases by 10% with the increasing iron sputtering time. All the studied CF_Fe fibers show good biocompatibility with osteoblastlike cells MG-63 cells after both 3 and 7 days of culture. Osteoblasts adhere to the fiber surface and show correct morphology. [ABSTRACT FROM AUTHOR]

Tb[sup 3+]-doped Lu[sub 2]O[sub 3] sintered ceramics were prepared in vacuum and in air. It was shown that the vacuum-sintered disks are able to store energy when irradiated with 300-nm or shorter photons. A small part of the stored energy could be recovered with 980-nm light. A much more significant amount of the stored energy could be released with red 647-nm photons. However, recovering the total stored energy could be accomplished only upon heating up to about 300 °C. Changes in absorption of the raw materials upon ultraviolet irradiation and subsequent IR (980 and 647 nm) treatments or upon heating at 300 °C are presented and discussed. A model for energy storing and recovering through the various IR irradiations or through heating is presented. At least two distinct ways of hole trapping as Tb[sup 4+] or V[sub k]-center as well as creation off and F[sup +] is suggested. [ABSTRACT FROM AUTHOR]

In the present work, bismuth-doped CaAl 4 O 7 phosphor powders were obtained via modified Pechini citrate process and their photoluminescence, radioluminescence and thermally stimulated luminescence properties were studied down to 20 K. At room temperature excitation in UV led to broad-band 3P 0,1 → 1S 0 Bi3+ luminescence with three maxima located in blue-green part of spectrum as well as Bi2+ emission around 760 nm assigned to the 2P 3/2 → 2P 1/2 transition. At 150 K an additional Bi3+ emission band peaking at 370 nm appeared and its intensity increased significantly upon further cooling. The presence of a few luminescent centers of Bi3+ in CaAl 4 O 7 was assigned to the presence of defects disturbing the local symmetry of activator ions. The radioluminescence spectra showed only two bands, an intense one at 760 nm clearly related to Bi2+ and a very weak component at 555 nm associated with one of the Bi3+ sites. These two emissions were also observed in the thermoluminescence of the material following its exposure to X-rays. The Bi3+ luminescence is suitably positioned to contribute the cyan color to white-LEDs. Its quantum yield is satisfactory, close to 40%. The Bi2+ 720–850 nm emission is attractive for bioimaging as it appears in the Ist biological window. • A novel bismuth-doped CaAl 4 O 7 phosphor materials have been developed. • The phosphor exhibits a complex emission originating from both Bi3+ and Bi2+ ions. • Multicomponent broad-band emission in UV–Vis arises from a few Bi3+ centers. • Bi2+ luminescence appears in the Ist biological window. • Bi2+ emission is predominant in radioluminescence and TL spectra [ABSTRACT FROM AUTHOR]

A comparative study of the luminescent properties of singly Sm 3+ -doped and Sm 3+ ,Na + co-doped strontium aluminates: Sr 1−x Sm x Al 4 O 7 and Sr 1–2x Sm x Na x Al 4 O 7 (x = 0.001–0.1), as a function of activator concentration at room and low (77 K, 16 K) temperature is reported. Upon an excitation at 402 nm all samples exhibit intensive orange-red emission due to the characteristic 4f-4f Sm 3+ transitions with maximum located at around 598.7 nm. It was found that luminescence properties of both series of materials differ significantly. In SrAl 4 O 7 :Sm 3+ at least four distinct activator symmetry sites were identified, which is due to presence of charge compensating defects in the crystal lattice and tendency to form Sm pairs. Charge compensation through alkali metal co-doping led to a smaller perturbation of the local environment symmetry of Sm 3+ ions and significantly enhanced luminescence intensity. In SrAl 4 O 7 :Sm 3+ ,Na + only two of the four non-equivalent centers of Sm 3+ were found. One of them corresponds to isolated Sm 3+ ion occupying basically undistorted Sr 2+ symmetry site offered by host lattice but the other is associated with Sm 3+ ions forming pairs. Analysis of the luminescence decay traces of both types of materials showed a decreasing decay time constant with rising activator concentration what was mainly attributed to cross-relaxation processes between Sm 3+ ions. This effect was slightly more pronounced for the Sm 3+ ,Na + co-doped series due to higher population of Sm 3+ pairs. Fitting of the 4 G 5/2 state fluorescence decay to the Inokuti–Hirayama model indicated different dominant mechanisms of the self-quenching luminescence of Sm 3+ in SrAl 4 O 7 :Sm 3+ and SrAl 4 O 7 :Sm 3+ ,Na + , respectively, dipole-quadrupole interaction and dipole–dipole interaction. [ABSTRACT FROM AUTHOR]

Ce 3+ doped and Ce 3+ ,Mn 2+ co-doped calcium aluminoborate (CAB) phosphors were synthesised by solid-state reaction method and their optical properties were studied. X-ray powder diffraction, SEM and TEM studies indicated the crystallization of the main trigonal CaAl 2 B 2 O 7 phase and the presence of an additional non-crystalline phase. It was also observed that increasing dopant concentration promotes phase separation. Hence, both series of phosphors demonstrated the changes in luminescence properties via activator concentration variation. Upon UV excitation (λ ex = 310 nm) Ce 3+ doped and Ce 3+ ,Mn 2+ co-doped materials yielded intensive blue and pinkish luminescence, respectively. The spectra of CAB:Ce 3+ samples showed a broad emission band due to 5d→4f transition of Ce 3+ , which broadened and shifted to longer wavelengths with increasing dopant content. Mn 2+ co-doping caused appearance of another broad-band emission with a maximum of 680 nm, resulting from the 4 T 1 ( 4 G) → 6 A 1 ( 6 S) transition of Mn 2+ . Detailed analysis of the emission and excitation spectra as well as decay time traces as a function of dopant concentration showed that efficient resonant energy transfer mainly occurs between Ce 3+ and Mn 2+ incorporated in the non-crystalline phase in CAB material. The estimated values of energy transfer efficiency of CAB:Ce 3+ (3%),Mn 2+ (4%) is close to 52%. [ABSTRACT FROM AUTHOR]

Comparison of the luminescent properties of nanopowder, single crystal and single crystalline film of Pr 3+ doped Pr-doped Lu 3 Al 5 O 12 garnet (LuAG:Pr) prepared by the different technological methods is performed in this work using the time-resolved emission spectroscopy under excitation by synchrotron radiation with an energy of 3.7–25 eV at 300 K and 10 K. The notable differences in the properties of the Pr 3+ luminescence are observed in LuAG:Pr crystals and films caused by involving the Lu Al antisite defects and oxygen vacancies in crystals and Pb 2+ flux related dopant in films in the excitation processes of the Pr 3+ luminescence. At the same time, we have also found that the influence of host defects on the Pr 3+ luminescence is significantly smaller in the LuAG:Pr nanopowders. [ABSTRACT FROM AUTHOR]

A detailed analysis of the luminescence behaviour of Yb 3+ -doped and Yb 3+ -Tb 3+ co-doped strontium aluminates powders: Sr 1-x Yb x Al 4 O 7 (x=0.002–0.07) and Sr 1-x-y Yb x Tb y Al 4 O 7 (x=0.03; y=0.002–0.02) were performed. The studies of singly doped samples show that direct excitation of Yb 3+ by means of 2 F 7/2 - 2 F 5/2 absorption at 900–980 nm leads to Stokes Yb 3+ emission in the range of 970–1130 nm as well as bluish-green Yb 3+ cooperative luminescence (CL) whose energy doubles that of the NIR one. The effect of activator concentration and charge compensation through Na + co-doping on both Yb 3+ emissions were also studied. It was found that Na + addition enhanced Stokes Yb 3+ photoluminescence brightness, while the cooperative emission intensity appeared to be lower. In doubly Yb 3+ -Tb 3+ doped materials excitation at 980 nm led to cooperative sensitization of the Tb 3+ 5 D 4 level giving rise to its green 5 D 4 → 7 F J (J= 7 F 6 - 7 F 3 ) up-conversion luminescence with the dominant component around 542 nm. The cooperative energy transfer (CET) mechanism was proposed basing on the results obtained from emission and absorption spectra, decay kinetics as well as the dependence of UC luminescence intensity on NIR excitation power. [ABSTRACT FROM AUTHOR]

This paper presents the characteristics of magnesium aluminium silicate-gentamicin complexes for drug delivery systems. The work describes the results of studies on the successful introduction of gentamicin (an aminoglycoside antibiotic) into the interlayers of smectite clay and examines the possible use of intercalated smectite as a carrier for sustained drug release. Characterisation of magnesium aluminium silicate-gentamicin complexes was carried out by means of X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis and scanning electron microscopy with EDX analysis. The possibility of using the gentamicin intercalated smectite as a carrier for sustained release of the drug was investigated during in vitro study, in which the release rate of gentamicin from the smectite clay matrix was monitored based on absorption at 330 nm using a UV-Vis spectrometer and the kinetic of drug release was evaluated based on the zero-order, first-order, Higuchi and Korsmeyer-Peppas models. The results confirmed the efficiency of intercalation and indicate the potential for introducing gentamicin into the interlayer space of montmorillonite. Accordingly, the obtained material may thus be used as a drug carrier in modulated drug delivery systems. [ABSTRACT FROM AUTHOR]

Structural changes accompanying stabilization and carbonization processes of the two types of polyacrylonitrile (PAN) nanofiber precursors (pure PAN and PAN with carbon nanotubes) were studied using infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The fibrous membranes were preliminary stabilized in air followed by the two-step carbonization process under nitrogen atmosphere. IR absorption spectra showed that the introduction of a small amount of functionalized multiwall carbon nanotubes (MWCNT) into the PAN precursor has a significant impact on its stabilization process. Raman spectroscopy study showed that the structure of carbon nanofibers containing CNT is distinctly more ordered in comparison to pure carbon nanofibers. Based on the XPS analysis the concentration of heteroatoms and the type and amount of functional groups on the surfaces of both types of nanofibers were determined. The results indicate a high potential of functionalized MWCNT as a pyrolysis modifier of polymer precursor leading to the formation of carbon nanofibers with controlled structure and defined chemical state of the surface. [ABSTRACT FROM AUTHOR]

In the present work, yttrium aluminum garnet Y 3 Al 5 O 12−x N 2x/x (YAGN) was obtained using aluminum nitride (AlN) as a source of aluminum. YAGN was doped with the Ce 3+ ions (YAGN:Ce) in concentrations from 0.5 to 14 mol%. According to XRD analysis, the crystal structure of YAG is maintained with traces of Al 2 O 3 . Scanning electron microscope (SEM) studies showed that the nitrogen atoms are not quite uniformly incorporated into grains, which may easily lead to the formation of a number of various Y 3+ sites. This means that Ce 3+ ions can also occupy sites of different nitrogen/oxygen ratios. The probability of Ce 3+ entering different sites changes with the dopant concentration. The emission and excitation spectra of Ce 3+ exhibit concentration dependence. For concentrations in the range 0.5–7% emission bands are extended to longer and shorter wavelengths in comparison to the typical emission of Ce 3+ in YAG. With the increase in the concentration of active ions (10–14 mol%) excitation bands show further widening, and the emission bands shift gradually toward longer wavelengths, reaching the value of 45 nm for 14 mol%. The usefulness of these phosphors for application in white LED technology is discussed on the basis of the quantum efficiency of the emissions, luminescence decay times, and thermal quenching of the Ce 3+ emission. [ABSTRACT FROM AUTHOR]

Although the degradation of polylactide has been relatively well understood, there is still a lack of reliable data on the behavior of its composites at specific temperatures. This paper studies the hydrolytic degradability of polylactide/not activated smectite clay nanocomposites in the 6 weeks accelerated degradation at 80 °C which has not been widely documented so far. The composites with 3 wt%, 5 wt% and 10 wt% of smectite filler content obtained by injection molding were investigated and compared to the neat polylactide matrix material. The results of degradation at 80 °C were referred to the hydrolytic degradation at 25 °C and 37 °C. Macroscopic changes in the nanocomposites, their molecular weight and pH of medium was monitored during the degradation time. The influence of clay addition on the crystallization, glass transition and the melting temperature was also studied by differential scanning calorimetry (DSC). The DSC results show that the presence of smectite clay results in a shift of the onset peak for the melting temperatures towards higher values while for the glass transition towards the lower ones. A significant difference in degradation rate between the polylactide matrix and the polylactide/clay nanocomposites was also noted. The shortened degradation time of the nanocomposites increases their potential for use in biomedical applications, but also in disposable thermoplastic products which are increasingly used. [ABSTRACT FROM AUTHOR]

Tb 3+ and Yb 3+ co-doped calcium aluminate powders: Ca 1−x−y Yb x Tb y Al 4 O 7 (x = 0.02–0.06; y = 0.02), Ca 1−x−y Yb x Tb y Al 4 O 7 (x = 0.03, y = 0.01–0.07), Ca 1−x−y Yb x Tb y Al 4 O 7 (x = 0.01–0.05, y = 0.01) were synthesized by a modified Pechini citrate process and their optical properties were investigated. Upon excitation at 245 nm all studied samples yielded relatively strong Tb 3+ luminescence corresponding to the 5 D 4 → 7 F J and 5 D 3 → 7 F J transitions with the dominant component around 542 nm. The direct excitation of two Yb 3+ ions at 980 nm led to cooperative sensitization of the Tb 3+ 5 D 4 level giving rise to its green up-conversion luminescence. The up-conversion emission was also observed from higher 5 D 3 level of Tb 3+ , which is rather rare in high phonon frequency host materials. The effect of activator concentration and charge compensation by co-doping with Na + ions on luminescence properties were studied. It was found that Na + addition lowers disturbance/distribution of activator ions local symmetries and enhanced Stokes Tb 3+ photoluminescence brightness, while the up-conversion emission intensity does not appear to change noticeably then. [ABSTRACT FROM AUTHOR]

The main objective of the work was to create a layer of carbon nanofibre on the surface of the NiTi shape memory alloy. The coating process was carried out in three stages. First, polyacrylonitrile was deposited by electrospinning. Then it was stabilized at temperatures up to 250°C. The last stage was the carbonization performed below 1000°C. The microstructure of the obtained coatings was observed using a scanning electron microscope. The X-ray diffraction techniques were applied to analyze the coating structure. After the polyacrylonitrile deposition, the fibers had an average diameter of about 280 nm, and the final fibers were almost twice as tiny. The applied steps also changed the phase and crystalline state of the fibers, finally leading to the formation of amorphous-nanocrystalline graphite. [ABSTRACT FROM AUTHOR]

Abstract: Calcium aluminate powders co-doped with Yb3+ and Eu3+: Ca1−x−y Yb x Eu y Al4O7 (x = 0.02–0.06; y = 0.02), Ca1−x−y Yb x Eu y Al4O7 (x = 0.05, y = 0.01–0.07) were synthesized by a modified Pechini citrate process and their optical properties at 298 K and 77 K were investigated. Direct excitation of Yb3+ by means of 2F7/2 → 2F5/2 absorption at 980 nm leads to bluish-green luminescence centered around 488 nm due to the cooperative emission of Yb3+ and red emission of Eu3+ corresponding to 5D0 → 7F J (J = 0–4) transitions. The near-infrared to red up-conversion luminescence of Eu3+ was assigned to a cooperative sensitization mechanism. The effect of activators concentration and charge compensation by co-doping with Na+ ions on luminescence properties were studied in detail. Na+ addition led to narrowing of luminescence bands, suggesting smaller disturbance/distribution of activator ions local symmetries. This was associated with significantly enhanced luminescence brightness of Eu3+ under UV excitation and, surprisingly, with noticeably reduced efficiency of Eu UC emission upon near-infrared excitation. It was also concluded that Yb3+ pairs transfer preferentially their excitation energy to Eu3+ ions with the local symmetry perturbed by certain defects present in the crystal lattice. [Copyright &y& Elsevier]

Abstract: Two series of calcium gallate phosphors: Ca1−x Eu x Ga4O7 and Ca1−2x Eu x Na x Ga4O7 (x=0, 0.002, 0.01, 0.02, 0.03, 0.05) were synthesized by a modified Pechini method and their optical properties at 298 and 77K were investigated. In undoped CaGa4O7 upon 255nm excitation a bluish white emission (λ max=500nm) followed by an afterglow of the same color lasting for 10–20s was observed. Eu3+-doping quenched the host-related luminescence and the characteristic red emission of the dopant with maximum at 613nm appeared. Its excitation spectrum consisted of a broad band assigned to ligand to metal, O2−→Eu3+, charge transfer absorption and narrow lines arising from intraconfigurational transitions within the 4f6 states of Eu3+ ion. The effects of Eu3+ concentration and Na+ co-doping on the luminescence properties and decay kinetics were studied. Low temperature emission spectra showed that Eu3+ ions are positioned in environments of different symmetries. Their relative populations changed with the activator content. Co-doping with Na+ ions led to a remarkable reduction of the number of Eu3+ sites as well as to noticeable improvement of the luminescence brightness though it did not affect the decay time of the emission. The quantum efficiencies of singly doped CaGa4O7:Eu3+ were very low (in the range of 1–3.7%). Na+ co-doping improved this parameter leading to the highest efficiency of 11% for CaGa4O7:3%Eu3+,3%Na+. [Copyright &y& Elsevier]

Abstract: Results of structural and spectroscopic measurements of Sm3+ doped calcium aluminates: Ca1−x Sm x Al4O7 and Ca1−2x Sm x Na x Al4O7 (x=0.0005, 0.002, 0.01, 0.02, 0.03, 0.05) obtained by the modified Pechini method are presented. All samples yield intense orange–red emission under violet excitation (404.5nm). Narrow bands corresponding to characteristic f–f intraconfigurational transition of Sm3+ in excitation and emission spectra were observed. The influences of the concentration of Sm3+ as well as charge compensation by co-doping with Na+ ions on the luminescent properties of the phosphor were investigated. Detailed analysis of the emission spectra of Sm3+ doped and Sm3+,Na+ co-doped CaAl4O7 powders proved that activator ions substitute Ca2+ in the host. Co-doping with Na+ ions enhanced greatly the intensity of the luminescence. Concentration dependencies of the intensity of luminescence and its decay kinetics proved the emission quenching at higher dopant contents due to cross-relaxation processes between Sm3+ ions. Fitting of the 4G5/2 state fluorescence decay to the Inokuti–Hirayama model indicated dipole–dipole interaction as the dominant mechanism of the cross-relaxation processes. [Copyright &y& Elsevier]

Polymer-based nanocomposites containing biocompatible and bioactive nanocomponents seem to be excellent materials that could be used in many biomedical applications. The aim of this study was biological evaluation of resorbable polymer-based nanocomposites (PLA, PCL) and their modifications with ceramic nanoparticles (silica - SiO2, montmorylonit - MMT) or carbon nanotubes. The nanocomposites were seeded with the human osteoblast-like MG 63 cells. After 1, 3 and 7 days of incubation, Trypan blue exclusion test was used to determine the viability and number of cells. The cell population density depending on incubation time and cell population doubling time was calculated. The cell proliferation abilities on the all applied nanocomposites and on control material (polystyrene cell culture plate) were also compared. The number of cells growing on the nanocomposite surfaces increased with the incubation time. The cell viability was not decreased for all applied materials during the entire study (97-100%). The ceramic nanoparticles and carbon nanotubes modified the bone cell growth and proliferation rate. Results of this study confirm that all types of the nanocomposites are appropriate to the growing and proliferation of human osteoblast-like cells. [ABSTRACT FROM AUTHOR]

Nanocomposite polymer scaffolds for tissue engineering were prepared using leaching method. As a porogen there were used phosphate salts with different grain size (100-400 μm). Nanocomposite materials based on polylactide (PL/DLA) containing 2 wt% of ceramic bioactive nanoadditives (SiO2) were prepared. The nanoadditive was characterized by dynamic light scatering (DLS) (size) and the Brunauer-Emmett-Teller (specific surface area) methods. Morphology of the nanoparticles was observed using the transmission electron microscopy. The optimal concentration of the nanofiller in the polymer matrix was evaluated on the basis of in vitro tests of the nanocomposite foils contacted with osteoblast-like human cells of MG63 line. The morphology and porosity of the scaffold after leaching was evaluated using scanning electron microscopy and hydrostatic weighing. The bioactivity test made on the scaffolds demonstrated ability to nucleation of apatite structure on the material. [ABSTRACT FROM AUTHOR]

Abstract: HfO2 and HfO2:Eu powders were synthesized with Pechini method at temperatures in the range of 600–1500°C. Structural, radioluminescence and photoluminescence properties of the powders were investigated. The highest light output of about 20% of the efficiency of commercial GOS:Eu was found for materials containing 0.5% of Eu and prepared at 1500°C. The data shows, that further improvement of light output could be obtained if materials are processed at yet higher temperatures. Emission spectra indicate that Eu3+ experiences variety of symmetries of its surroundings. Undoped materials produce broad band emission peaking at 480nm and showing a significant afterglow. [Copyright &y& Elsevier]

Abstract: A comparative analysis of the luminescent properties of YAG and YAG:Ce nanopowders (NP) in comparison with single crystalline film (SCF) and single crystal (SC) analogues was performed under excitation by a pulsed synchrotron and X-ray radiation. It was shown that the natural defects concentration in NP was between the SC with a large (∼0.18–0.19at.%) concentration of YAl antisite defects (AD) and SCF of these garnets where YAl AD were completely absent. At the same time, Ce3+ doped YAG NP showed luminescent properties close to those of YAG:Ce SCF. [Copyright &y& Elsevier]

Abstract: Raman spectroscopy, a non-destructive technique, appears to be a very useful research technique in archaeology and geology. In the presented study Raman spectroscopy proved to be an efficient, fast and informative tool to determine the provenance of archaeological objects found in the excavations of Lower Silesia (Poland). The combined spectroscopic, X-ray powder diffraction and petrographic methods allowed for determination of the provenance and the mineralogical composition of archaeological vessels manufactured in late 9th and the turn of the 10th century that were found in Gilów located at the Sudety Foothils (south-western Poland). The analysis revealed that most of the investigated ceramics were manufactured locally, however two out of three investigated pottery groups show influence of south style originating from Moravia, a historical region located in the Eastern part of Czech Republic and South of Gilów. [Copyright &y& Elsevier]

Abstract: Molten salt synthesis procedure, homogeneous precipitation with urea and -flux aided routes are presented as interesting fabrication methods for making oxide luminescent materials. The properties of the powders made using these techniques are presented and analyzed. Emphasis is put on spectroscopic characterization of the products. [Copyright &y& Elsevier]

Abstract: Nanocrystalline Lu2O3 doped with 1at.% of Eu was obtained precipitating hydroxide of lutetium with urea at 80°C from water solution and decomposing the hydroxide to oxide at 500°C. Polyvinyl alcohol was used to hinder the particles growth during precipitation. The average size of the fabricated particles was 2–5nm. Although at 500°C the hydroxide decomposed to Eu-doped Lu2O3 traces of OH impurities were present in the material unless heated at 1200°C. Radioluminescence was very poor for samples heated at 800°C or lower temperature. After heating the precipitated powder at or above 1200°C the efficiency jumped 45 times reaching 75% of the output from commercial microcrystalline Gd2O2S:Eu. The properties make nanocrystalline Lu2O3:Eu prepared in the described way a promising X-ray phosphor for planar digital medical imaging. [Copyright &y& Elsevier]

The paper reports on the course of decomposition of hydrated lutetium nitrate and lutetium chloride to Lu2O3 in the eutectic mixture of NaNO2 and KNO2. It was shown that a crystallographically pure phase of the cubic Lu2O3 is formed at temperature as low as 250 °C. IR spectra revealed that the recovered powder contains some OH-contamination, however. The powders are characterized by crystallites sizes in the range of 18–30 nm in average. Emission and excitation spectra of Eu-doped powders show characteristic features for Eu3+ ion in an oxide host, which indicates that the procedure is appropriate for making activated nanoparticulate oxide phosphors. Most profound emission appears around 611 nm and the luminescence from the powder made starting with Lu(NO3)3 was noticeably higher compared to the product obtained from LuCl3. The excitation spectrum of Eu3+ emission at 611 nm contains a band related to the fundamental absorption of the lutetia host lattice, which indicates an existence of the host-to-activator energy transfer. [Copyright &y& Elsevier]

Two series of Lu2O3:Eu nanocrystalline phosphors were prepared using either combustion procedure with urea fuel or the Pechini procedure. The dopant concentration varied in both series from 0.2 to 13% with respect to Lu. Despite full crystallization and very similar microstructure of materials of both series, we found profound variations in their spectroscopic properties. The combustion-made phosphors were much less efficient emitters and their emission was strongly concentration-quenched above 3% of the dopant content. For the Pechini-derived materials, the concentration quenching was not observed below 10% of the dopant content and even for the dopant concentrations equal to 10 and 13% the quenching was insignificant. In EPR spectra for Gd3+-doped materials, a significant broadening of lines was found for the combustion-made powders. All these observations imply a strong agglomeration of the dopant ions in the specimens made by applying urea fuel in the combustion process. A semi-two-phase composition was suggested in the combustion-prepared powders. In the Pechini-derived nanocrystalline powders, the dopant ions are uniformly, statistically distributed in the host lattice. [Copyright &y& Elsevier]

Efforts to obtain translucent pellets of BAM for Martian UV-dosimeter were undertaken. Sinterability of both commercial BAM powder and a Pechini-derived one was examined. The commercial phosphor sinters with difficulty only, while the one made with Pechini procedure sinters easily and translucent pellets could be obtained in such a way. Vacuum sintering at 1750 °C for 15 h was also enough to fully convert Eu3+ into Eu2+ in the sintered pellets without the necessity of using hydrogen-containing gas. The spectroscopy of the sintered BAM differs noticeably from its commercial powdered counterpart. The excitation is much more flat in the entire UV and especially strong enhancement of the excitation efficiency is observed in the near-Vis part of the UV region. Decay kinetics is exactly the same for commercial powder and sintered ceramic, which proves the lack of luminescence quenching in the latter. The sintered pellets of BAM made in our laboratory show mechanical and spectral characteristics, which make the material suitable for Martian UV-dosimeter. [Copyright &y& Elsevier]

Nanocrystalline powders of Lu2O3:Eu with the activator content varying in the range of 0.2–10% were prepared through a combustion technique. The powders were only slightly agglomerated and the size of crystallites were about 30 nm. Some of the powders were co-doped with Mg, Ca, Sr, Ba, La of various concentrations. Such powders were cold-pressed and sintered at 1750°C for 5 h in vacuum. X-ray-excited luminescence spectra of both the powders and the sintered ceramics were recorded and the efficiency was compared to the commercial standard Gd2O2S:Pr,Ce,F X-ray phosphor. It was found that the nanocrystalline powders of Lu2O3:Eu,Ca emit photons four-times less than the commercial micron-sized Gd2O2S:Pr,Ce,F powder. In the case of sintered materials the emission efficiency from our Lu2O3:Eu5%, Ca was roughly equal to the efficiency of the commercial-sintered Gd2O2S:Pr,Ce,F. The co-doping ions were shown to have various effects on the transparency of the sintered Lu2O3:Eu. Mg hindered the sintering process producing completely opaque pellets. Other ions facilitated the sintering course and the best results were obtained by co-doping the samples with 0.5% of Ba. Sr and La also significantly stimulated the sintering and the final pellets were only slightly cloudy. [Copyright &y& Elsevier]

Uranium(3+) doped Cs2NaYBr6 single crystals with a 2.1 and 0.09 mol% U3+ concentration have been obtained by the Bridgman–Stockbarger method. The U3+ ions replaced the Y3+ ions at an octahedral site of Oh symmetry. Luminescence spectra of the crystal were recorded at 4.2 K. The emission bands observed in the visible and near infrared regions have been assigned to transitions from the lowest components of the 4G7/2 and 4F3/2 multiplets to the crystal-field components of the 4I9/2 ground state. Absorption spectra were recorded in the 3900–35,000 cm−1 range at 4.2 K. The analysis of these spectra enabled the assignement of 28 energy levels, which were fitted to seven parameters of an empirical Hamiltonian representing the combined atomic and crystal-field interactions, with a rms deviation of 43 cm−1. The energies of the most prominent vibronic features have been measured and assigned to the specific vibrational modes of the UCl63− moiety or to lattice modes. Above 14,000 cm−1 vibronic transitions associated with the electric dipole allowed 5f3–5f26d1 transitions were observed. The unresolved zero-phonon lines are accompanied by a number of vibrational progressions combined with the even S1(a1g) mode. [Copyright &y& Elsevier]

Preparation and optical properties of Lu2O3/Eu3+ nanocrystals embedded in silica gel glass are described. The structure of the obtained ceramics was determined by XRD and transmission electron microscopy. It was found that with increasing sintering temperature the Lu2O3/Eu3+ nanocrystallites underwent transformation into monoclinic Lu2Si2O7 nanocrystallites. The fluorescence properties were investigated as a function of thermal treatment of the samples. It was found that after sintering at 1250 °C the fluorescence lifetime increased to 1.5 ms at room temperature. The material studied in this work exhibits a very high intensity of fluorescence with potentials for display application. [Copyright &y& Elsevier]

Decay kinetics and X-ray diffraction patterns of Lu 2 O 3 :Eu with concentration of the dopant spanning 0-20% were measured for two series of materials with crystallites sized of 13 nm and 35 nm. For the series of smaller crystallites a very significant concentration quenching was observed, while for the larger crystallites the effect was minor only. Detailed structural analysis made it possible to postulate that this effect is related to an inhomogeneous distribution of Eu 3+ ions within the smaller crystallites. [ABSTRACT FROM AUTHOR]

The size effect of nanoparticles on optical properties of Lu2O3:Eu3+ was investigated. No pronounced effect was observed for structure of emission spectra. It was found that effect is mainly manifested in the decay profiles of Eu3+ emission. We have noticed that the decay times were almost the same for low concentrations of Eu3+ ions. It is concluded that the size effect is associated with agglomeration of Eu3+ in nanorange particles. [Copyright &y& Elsevier]

Nanoparticulate powders of Eu-doped Lu2O3 were prepared using combustion process and glycine as a fuel. Such powders could be relatively easily sintered to translucent bodies at 1700 °C. Excitation and emission spectra were recorded for both types of the materials. The excitation spectra revealed the existence of much more efficient energy transfer from the host to the dopant in the sintered ceramics. Strong variations in the relative intensities of the excitation transitions are seen when comparing the powder and its sintered analog. This was explained assuming preferential occupation of the C3i site in the glycine-derived powder in comparison with the pellets. Most profound emission under X-ray excitation was found for the sintered ceramic doped with 5% of Eu. [Copyright &y& Elsevier]

Using combustion synthesis and urea as a fuel, Lu2O3 powders were prepared and their morphology defined with HRTEM measurements. The powders were sintered at 1700 °C for 5 h and the microstructure of the obtained ceramics was characterized. It turned out that the as-made powders were strongly agglomerated compositions with a mean particle size of 15–25 nm. High-temperature sintering caused some increase in the size of the crystallites, diameter increased to an average of 25–35 nm. However, domains of about 200–300 nm diameter were formed. These were separated by relatively broad transient regions. The inter-domain regions of rather ample thickness are blamed for relatively high scattering of the sintered ceramic specimens. The formation of the domains is correlated to the existence of agglomerates in the urea-derived nanoparticulate powders. [Copyright &y& Elsevier]

Lu2O3 doped with Eu of varying concentrations was prepared using a convenient combustion technique. Emissions from two different crystallographic sites, C2 and S6, were found and analyzed. Using various spectroscopic techniques, luminescence of Eu3+ exclusively from site C2 or site S6 could be detected. Kinetics of both emissions was characterized and time constants of 1.5 and 4.3 ms were found, respectively. Energy transfer from Eu3+ in site S6 to Eu3+ in site C2 was proved to take place when the dopant content reaches about 1% or higher. For rising activator concentration the transfer becomes more efficient and for heavily doped samples the emission from S6 site lasts in a vestige form only. The only emission transitions detected from Eu in centrosymmetric site S6 were the 5D0–7F1 three-line band. [Copyright &y& Elsevier]

Spectroscopic properties of Lu 2 O 3 :Tb pellets sintered at 1000 C or 1700 C were investigated. The sintering temperature did not influence the optically excited emission and excitation spectra of the materials. However, the treatment temperature did influence the emission under cathode-rays stimulation. While the specimens sintered at 1000 C showed only luminescent lines above 480 nm resulting from a radiative relaxation of the 5 D 4 level, the samples heated at 1700 C did show some luminescence in the blue region resulting from 5 D 3 → 7 F J emission. The blue emission could be recorded exclusively upon cathode-rays irradiation. [ABSTRACT FROM AUTHOR]

Abstract: La2Hf2O7 nanopowders doped with different Pr concentrations (0.05–10mol.%) were synthesized by the Pechini method. XRD measurements confirmed the single crystalline phase formed already at 800°C and the structure was cubic pyrochlore. Luminescence excitation and emission as well as radioluminescence spectra were recorded for the materials. Both optical and X-ray excitation of La2Hf2O7:Pr produced a red emission resulting from the 4f–4f transitions of Pr3+ ions. Luminescence of materials synthesized at low temperatures was characterized by broadband glass-type emissions, while heat treatment at 1400°C led to spectra showing the typical for crystalline hosts narrow and intense 4f–4f transitions of Pr3+. [Copyright &y& Elsevier]

Phase-pure orthorhombic α′- and monoclinic β-Sr2SiO4 and its Ce3+- or Eu2+-doped versions are prepared by reaction of stoichiometric amounts of SrCO3, SiO2, CeO2 or Eu2O3 in the presence of 1 wt% H3BO3 or 1-50 wt% SrCl2 as fluxes in different atmospheres (1200-1400 °C, 4 h; in air, vacuum, 5% H2/N2, or 25% H2/N2). [ABSTRACT FROM AUTHOR]

The present paper concerns the potential use of montmorillonite as a drug carrier and focusses on the intercalation of the studied clay with gentamicin (an aminoglycoside antibiotic) at various temperatures (20, 50 and 80 °C). The experiments were performed to identify the temperature required for the optimum intercalation of gentamicin into the interlayer of montmorillonite. The structural and microstructural properties of gentamicin and the potential for introducing it between smectite clay layers were investigated by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopic techniques, and SEM with EDS analysis. Additionally, the in vitro drug release behaviour of the montmorillonite-gentamicin complex and its antibacterial activity against Escherichia coli ( E. coli ) bacteria was investigated. Based on these studies, the impact of temperature on the intercalation of the drug between layers of smectite was evaluated. It was found that an intercalation temperature of 50 °C resulted in the highest shift in the position of principle peak d (001) as measured by XRD, suggesting, that the greatest amount of gentamicin had been introduced into the interlayer space of montmorillonite at this temperature. Subsequently, the montmorillonite-gentamicin complex material obtained at 50 °C revealed the greatest capacity for killing E. coli bacteria during an in vitro test. [ABSTRACT FROM AUTHOR]

Abstract: Novel materials for regenerative medicine are usually composites or nanocomposites. Their main task is to stimulate damaged tissue for faster regeneration caused by enhanced activity of cells prone to intense proliferation within the defect area. One of the main requirements for such materials is bioactivity, which accelerates fixation between the material and surrounding tissue. After implanting into the body, bioactive materials create new physicochemical bonds between the material and the surrounding tissue. In their case apatite layers are formed on the implant surface without inducing growth of fibrous tissue around them. Some differences in bioactivity phenomena observed on the surface of materials depend on the mechanism of bonding and/or time required to create a new bonding and its strength. In the case of some polymers, especially with highly porous or fibrous structures, the bioactivity phenomenon is initiated by local increase in concentration of calcium and phosphate ions which become nuclei of apatite crystallization. The work presents time-dependent results of interactions between nanocomposite foils and simulation body fluid solution (SBF). Nanocomposite foils were produced from chitosan (CS) and montmorillonite (MMT). The obtained foils, CS and CSM (CS+MMT) were subjected to bioactivity tests by incubation in SBF for different time. FTIR measurements were carried out on an Excalibur spectrometer using ATR method in the wave number region from 550cm−1 to 4000cm−1. The reaction between foils and SBF was analyzed by 2D IR correlation spectroscopy The data obtained show local supersaturation of some characteristic groups in CS-MMT material which seems to be the result of apatite nucleation. [Copyright &y& Elsevier]

Abstract: Bulk alkaline earth fluorides co-doped with optically active ions are prominent materials for luminescent applications. However, for phosphor materials the changeover to the nanoscale is a tightrope walk between achieving desirable features of small particles such as reduced light scattering and unwanted drawbacks such as a high surface defect concentration which is likely to result in quenching of luminescence. A new preparation route via ionic liquids allows obtaining pure and oxygen-free alkaline earth fluorides co-doped with Eu3+ and Gd3+ on the nanoscale with excellent quantum cutting abilities. [Copyright &y& Elsevier]

Abstract: Ca1− x Eu x Al4O7 (x =0, 0.002, 0.01, 0.02, 0.05, 0.1) and Ca1−2 x Eu x Na x Al4O7 (x =0.002, 0.02, 0.05, 0.1) crystalline phosphor powders have been synthesized by modified Pechini method and their spectroscopic properties at room and liquid nitrogen temperature were measured. Excitation spectra of synthesized materials contain broad band attributed to ligand to metal, O2−→Eu3+, charge transfer absorption and narrow lines related to 7F0→5D J , 5H J , 5L J , 5G J transitions of europium ions. Upon excitation at 395nm, the Eu3+-doped calcium dialuminates exhibit red photoluminescence due to parity forbidden f–f intra-configurational transitions with the most intense component at 612nm resulting from the 5D0→7F2 hypersensitive transition. The quantum efficiency of the powders emissions does not exceed 12%. The luminescence decay kinetics reveals that some quenching appears for higher concentrations. Site selective spectroscopy disclosed the presence of at least two well defined individual spectroscopic sites of Eu3+ and increasing disturbance of their local symmetries with raising concentration of the activator was observed. The increasing symmetry disorder led to a significant asymmetrical broadening of the luminescence lines at higher concentrations. Concentration dependence of the luminescence kinetics of the two diverse Eu3+ ions is different, as only one of them, with the characteristic luminescence at 579.5nm, exhibits shortening of the decay time at higher Eu contents. The inexpensive CaAl4O7:Eu powders are potentially good candidates for photonics applications. For Eu, Na co-doped powders the Eu3+ ions producing emission at 579.7nm dominates strongly over those with luminescence at 577.2nm. [Copyright &y& Elsevier]

Abstract: A mechanism of creating maxima in directional elastic peak electron spectroscopy (DEPES) polar profiles for textured polycrystalline samples and for amorphous samples with a short-range atomic order is proposed and discussed. DEPES was used in investigating the atomic order in Al and W polycrystalline samples. The maxima found in DEPES polar profiles correspond with the texture expected for these samples on the basis of literature data. A method of processing DEPES data of amorphous metallic alloy with a short-range atomic order is proposed and successfully used for an Al0.6W0.4 alloy. The results obtained indicate that nanocrystals with an average linear size in the range of 1nm and with a particular orientation with respect to the sample surface are present in the surface layer of the sample investigated. A concentration of nanocrystals with such orientation equal to 1.9×1019/cm3 was found when using of the contrast obtained for the maximum in the DEPES polar profile, corresponding to an incidence angle of zero. The contrast of DEPES profiles for the Al0.6W0.4 sample increases remarkably during annealing at 373K. An increase in the amount of preferentially-oriented nanocrystals is suggested as the probable reason for this increase. [Copyright &y& Elsevier]

The remote temperature readout capability offered by luminescent thermometry has high application potential. Designing thermometers with predefined thermometric parameters is only possible by understanding the processes responsible for temperature-induced changes in the spectroscopic properties of phosphor. One of the key factors, that should be considered, is the influence of the morphology of the phosphor on their spectroscopic properties. In this work, we present for the first time an analysis of the influence of material morphology on the thermometric properties of a ratiometric luminescent thermometer based on the luminescence intensity ratio of 2E→4A 2 to 4T 2 →4A 2 emission bands in Gd 3 Ga 5 O 12 :Cr3+ nanocrystals, microcrystals and optical ceramics. As shown, limitations in the thermal coupling between the 2E and 4T 2 levels occurring in the cryogenic temperature range allowed to achieve a relative sensitivity of 5.8%/K at 11 K in optical ceramics compared to 2.6%/K and 1.95%/K in microcrystals and nanocrystals, respectively. • Thermometric properties of Gd 3 Ga 5 O 12 :Cr3+ were investigated. • Nanocrystalline, microcrystalline and optical ceramic were compared. • Supersensitive thermometer operating in a cryogenic temperature range was presented. [ABSTRACT FROM AUTHOR]

Abstract Perfectly transparent ceramics of La 0.4 Gd 1.6 Zr 2 O 7 doped with either Eu3+ or Pr3+ ions were prepared by high-temperature vacuum sintering. Results of the Rietveld structure refinement and spectroscopic properties of the ceramics are presented and discussed in details. Photoluminescence characteristics support the non-uniformity in the crystal structure of ceramics. X-ray excited luminescence of La 0.4 Gd 1.6 Zr 2 O 7 :Eu was rather inefficient and the Pr-doped ceramics showed no Pr-related radioluminescence. Instead they produced Eu3+ emission characteristic for Gd 2 O 3 :Eu phase not detected in X-ray diffraction patterns. Highlights • Structure refinement of La 0.4 Gd 1.6 Zr 2 O 7 transparent ceramics revealed non-uniformity of its crystal structure. • Photoluminescence confirmed the multisite occupancy of the activator in Eu3+/Pr3+-doped La 0.4 Gd 1.6 Zr 2 O 7 transparent ceramics. • The Eu3+ presence as well as gadolinia contamination was analyzed through photo-/radioluminescence. [ABSTRACT FROM AUTHOR]

Lu 2 O 3 :Pr,Ti storage phosphors were prepared by means of high temperature (1700 °C) sintering both in a reducing atmosphere of the N 2 -H 2 mixture (3:1 by volume) and in ambient air. Their thermoluminescent (TL) properties were presented and discussed. Pr singly-doped material showed only very inefficient TL. Ti co-doping boosted the TL efficacy, and the most potent TL was observed for ceramics containing 0.05 mol% of Pr and 0.007 mol% of Ti and made in the reducing atmosphere. Samples prepared in air produced noticeably less intense TL. The glow curves of both materials consisted of one broad asymmetric band with the maximum around 357 °C for the heating rate of 4.7 °C/s. The glow peaks could be fitted with three (reduced samples) or two (air-sintered) components. The latter lacked the high-temperature part of TL compared to the former. T max -T stop experiments indicated that the TL is connected with continuous distribution of trap depths, which were estimated to cover the range of ~ 1.7 to 2.3 eV, and their specific values were slightly dependent on the methodology. Anomalous dependence of the TL intensity on the heating rate made the semi-localized transition the likely mechanism affecting the TL properties of Lu 2 O 3 :Pr,Ti ceramics. The collected data allowed to construct vacuum referred binding energy (VRBE) level scheme with Pr 3+ and Ti 3+/4+ energy levels in the band gap of Lu 2 O 3 host that could explain the TL mechanism in Lu 2 O 3 :Pr,Ti ceramics. [ABSTRACT FROM AUTHOR]

Mixed Lu x Y 1-x VO 4 crystals, undoped and doped with Eu 3+ , were synthetized by the solid state reaction method. The crystal structure and phase composition were controlled by the X-ray diffraction (XRD), Raman analysis, and scanning electron microscope (SEM) measurements. The samples' crystallinity was improved by annealing. Nevertheless, the lattice distortion caused by the substitution of Y by Lu was detected. The lattice parameters derived from the XRD data are in good agreement with the calculated ones. It was found that the luminescence intensity increase in the annealed samples is related to the improvement of crystallinity of samples. According to the studies of X-ray excited luminescence at 300 K the relative luminescence intensity increases for the samples with intermediate values of x. For the Lu x Y 1-x VO 4 :Eu 3+ the highest luminescence intensity was detected for x=0.7 and ascribed to the effect of decrease of the mean distance between the thermalized electrons and holes. For the undoped crystals the luminescence is partially quenched at 300 K, however the sample with x=0.7 demonstrate highest intensity as well. The effect in the undoped samples is due to the increase of the temperature of luminescence quenching in samples with intermediate values of x. [ABSTRACT FROM AUTHOR]

BaHfO 3 sintered ceramic scintillators doped with various Pr concentrations (0–1 mol%) were synthesized at 1700 °C in N 2 –H 2 atmosphere. XRD, SEM and photo-luminescent techniques at various temperatures (40 K to 550 K) were employed to reveal properties of the BaHfO 3 :Pr ceramics. Results of spectroscopic investigation indicate that the luminescence is connected almost exclusively with decay of the 3 P 0 level, while the emission from 1 D 2 is hardly seen even for higher Pr 3+ concentrations. However, the intrinsic emission of BaHfO 3 matrix, related with defects or impurities, seems to compete with the emission of Pr 3+ ions. The 3 P 0 luminescence decays give time constant of about 25–32 μs in the 40–550 K range of temperatures, while the 1 D 2 decay time depends on the dopant concentration and gets shorter above 300 K for 1% specimen due to a cross relaxation process between Pr 3+ ions. [ABSTRACT FROM AUTHOR]

Monoclinic monazite-type Nd 3+ -doped lanthanum orthophosphate (LaPO 4 :Nd 3+ ) nanoparticles were prepared by microwave treatment of simple lanthanide precursors such as Nd(OAc) 3 •xH 2 O, OAc = acetate) with task-specific dihydrogen phosphate ionic liquids (ILs) 1-butyl-1-methylpyrrolidinium dihydrogenphosphate- BmPyrH 2 PO 4 (IL1) and 2-hydroxyethyl-N,N,N-trimethylammonium, [choline][H 2 PO 4 ] (IL2) as the reaction medium, reactant and in-situ nanoparticle stabilizer. This synthesis route possesses many advantages as it is a fast and facile preparation method of the desired phosphate nanomaterials without the necessity for post-reaction heat treatment to obtain the anhydrous high temperature monazite phosphate phase. The nano-sized phosphors Nd 3+ :LaPO 4 were carefully analyzed by the powder X-ray diffraction, electron microscopy and spectroscopic techniques taking advantage of the Nd 3+ spectroscopic probe to analyze in detail the structural properties. Applied high resolution low temperature absorption and emission techniques allowed to complete the structural information unavailable from the XRD powder patterns. A clear influence of the used task-specific dihydrogen phosphate ILs on the structure, morphology, luminescence intensity and lifetimes of the obtained Nd 3+ :LaPO 4 was found. It is worth noting that the Nd 3+ luminescence in LaPO 4 has never been reported up to now. [ABSTRACT FROM AUTHOR]

We show the opportunity for tuning of the spectral position of the Mn4+ red emission in the series of double perovskites, Ba 2 LaNbO 6 :Mn4+, Ba 2 La(Nb 0.8 ,Zr 0.1 ,W 0.1)O 6 :Mn4+, and Ba 2 La(Zr 0.5 ,W 0.5)O 6 :Mn4+ with increasing chemically induced symmetry disturbance. Such a disorder appeared attractive to engineering phosphors for pressure sensors or horticultural applications, for instance. The goal of the present research, not yet systematically addressed in the literature, was to unveil the correlation between chemically induced controlled crystal lattice distortion and the luminescence of Mn4+. For this purpose, the luminescence of these phosphors was methodically investigated at different pressures and temperatures. A pressure-induced redshift of photoluminescent lines with the rate of − 4 cm−1/kbar was found within the 0–230 kbar range, and the emission peak moved from 685 to 740 nm then. Furthermore, the cationic disorder allowed tuning of the Mn4+ luminescence making it useful for horticultural applications with a better fit between the emission wavelength and the strong chlorophyll absorption in the deep red part of the spectrum. The Mn4+ energy levels were computationally determined using the exchange charge model of the crystal-field theory which allowed for a deeper understanding of the experimental results. We found a correlation between the introduced disorder of the cationic subsystem and the energy of the Mn4+ emitting 2E g level (R-line) as well as its intensity. This research brought a deeper understanding of the Mn4+-activated phosphors and, in turn, provides tips for a prudent search of materials for advanced practical uses. [Display omitted] • The Ba 2 La(Nb 1–2x Zr x W x)O 6 :Mn (x = 0;x = 0.1;x = 0.5) isostructural phosphors are reported. • The influence of pressure and temperature on the luminescence of Mn4+ is presented. • Effects of chemically induced partial cation substitution are investigated. • Theoretical studies support the understanding of the experimental dependencies. • The findings provide tips for a deliberate design of phosphors for advanced uses. [ABSTRACT FROM AUTHOR]

Review: [discussion of the properties of the broad-band luminescence around 425 nm in the temp. [ABSTRACT FROM AUTHOR]