This study compares HfO2 ceramics synthesized using sol–gel and combustion methods, emphasizing the impact of the method of synthesis on the resulting properties of the material. The research findings illustrate morphological differences between sol–gel and combustion-derived HfO2. While sol–gel samples displayed irregular nanoparticles with pronounced boundaries, combustion samples revealed more homogeneous structures with particles tending towards coalescence. It was discerned that Eu3+ doping induced oxygen vacancies, stabilizing the tetragonal phase, while subsequent doping with Nb5+ significantly reduced these vacancies, which was also observed in photoluminescence analysis. Furthermore, combustion synthesis left fewer organic residues, with urea presence during synthesis contributing to residual organic components in the material. XPS analysis was used to evaluate the presence of oxygen-deficient hafnia sub-oxide in the samples. The study underscores the important role of tailored synthesis methods in optimizing the properties and applications of HfO2.

Lanthanide ions possess unique optical characteristics and can be used as luminescent probes; however, the characteristics and effect of lanthanide ion incorporation into metal-oxide host matrices have not been thoroughly researched up until now. In this study, we investigate the incorporation characteristics of Eu^3+ such as whether threefold or fourfold-coordinated oxygen vacancies are created, the charge of the created oxygen vacancies, and whether the lanthanide ions incorporate in pairs or as single ions. Undoped, 5 at. HfO_2 were synthesized by sol–gel and combustion methods. All samples were of monoclinic phase. Photoluminescence, thermoluminescence, XRD, and luminescence decay kinetics were used to determine the impact of dopants on the HfO_2 matrix. A mechanism for Eu^3+ ion incorporation in pairs or individually is considered.

This work demonstrates an effect which would allow a reduction in the number of baking steps in a post-development process for a system consisting of the SU8 photoresist with nanoparticles, in which up-conversion luminescence can be excited. Traditionally, writing structures in photoresists involves several steps, e.g. the I-line method requires a UV light source as the writing element, and several bake procedures (post-bake and hard-bake) in the post-development process. Photoresist mixed with nanoparticles (e.g. NaYF4 doped with Tm3+ and Yb3+) makes it possible to use up-conversion luminescence, which opens up new opportunities in photolithography. One opportunity includes recording structures by means of up-conversion luminescence using nanoparticles mixed into the photoresist as a UV light source. However, this work is related to another possibility: the reduction of the number of bake procedures in the post-development process when the structures in the SU8 photoresist are mixed with nanoparticles (NaYF4:Tm3+:Yb3+) that emit visible and ultraviolet light under infrared excitation. It will be shown that NaYF4:Tm3+:Yb3+ nanoparticles act not only as a UV light source, but also as local heaters. Such a double application allows to record structures and thermally fix them simultaneously while retaining the physical properties, which were evaluated using structure hardness measurements and dissolution experiments with two type of solvents (2-propanol and acetone)

This article explores the development of a small, compact fiber-based spectrometer system designed to overcome the limitations of standard spectrometers, such as the high cost and restricted accessibility.Operated by a Raspberry Pi, the fiber-based spectrometer system uses the increased computing power to provide versatile modes of operation and powerful data processing, while maintaining a small size. Specifically crafted for basic chemistry and biology lab setups, where fibers allow measurements in different conditions, and customization enables fluorescence, light scattering, and absorption measurements.The system is adaptable and versatile, offering ease of modification and adaptation for a broad range of applications.

Hafnia has already been established in CMOS technologies as a high-k metal gate material, however, recently it has also become a promising material in ferroelectric applications. In this study we have investigated intrinsic defects such as oxygen vacancies in undoped and 5at%Eu HfO2 synthesized by sol-gel, combustion, auto-ignition combustion, hydrothermal and precipitation methods. All samples were of monoclinic phase with crystallite sizes of 16-40 nm. Photoluminescence (PL), thermostimulated luminescence (TSL) both below and above room temperature as well as XRD and TEM methods were used to identify potential VO+1 defects. Activation energies were determined for the oxygen vacancies and grain boundary effects were studied. Both PL and TSL wavelength peak spectra shift to higher energies with the increase of temperature was observed.

The use of stress–strain analysis in structural design or mechanical components is critical for avoiding or investigating structural failures. In the case of complicated designs, mathematical full-field stress modeling produces imprecise predictions. Experimental analysis can be used as a replacement for mathematical modeling, but with the use of currently available strain gauges, it is cumbersome and impossible in the case of moving parts. Mechanoluminescent materials transform mechanical energy into visible light and can be used as a replacement for strain gauges to monitor strain/stress. Three-dimensional printing technology has made major advances in terms of additive manufacturing. In this article, we describe a method to produce an ML 3D print. The fabricated samples are precise and versatile and satisfy the need for easy and non-destructible spatial stress analysis. A 3D printed photopolymer sample with SrAl2O4: Eu, Dy particle addition only to the final layers was tested, and the number of layers was optimized. It was determined that the optimal number of layers for easy detection is in the range of 10 to 20 layers. It opens the possibility for the real-time evaluation of complex uneven forces on complex parts, thus having a good potential for commercialization.

The purpose of this study was to reveal the effect of printing direction and post-printing conditions on static and fatigue bending characteristics of Ultem 9085 at two stress levels. Right after the printing, the Ultem samples were subjected to three cooling conditions: cooling in the printer from 180 to 45 °C for 4 h, rapid removal from the printer and cooling in the oven from 200 to 45 °C during 4 h, and removal from the printer and cooling at room temperature. Static 3-point bending tests were performed to estimate the flexural characteristics of Ultem 9085 samples after subjecting them to different post-printing conditions. The flexural strain was evaluated and applied for the stress ratios such as 75% and 50% of σmax. Thus, displacement-controlled fatigue tests were carried out to reveal the effect of post-printing conditions on fatigue bending characteristics. The results obtained for the X and Y printing directions proved that the Ultem samples subjected to the cooling conditions in the printer and the oven had a similar static and fatigue behavior, while a lower performance was obtained for the samples cooled at room temperature. Regardless of the cooling regime, significantly lower bending performance was revealed for the samples printed in the Z-direction since they have intra-layer filaments parallel to the stress plane, and, accordingly, intra-layer adhesion has a crucial influence on mechanical performance.

This paper outlines an innovative method for a modification of precise and versatile 3D printing technology to satisfy the need for easy and non-destructible spatial stress analysis on printed mechanical parts. A 3D printed photopolymer sample with SrAl2O4:Eu,Dy particle addition is tested and a following method of data processing for spatial stress mapping is offered. The empirical stress distribution maps is proven to be in accordance with the calculated stress distribution and can therefore be further developed for technological applications offering a good addition for computational stress–strain analysis. It opens the possibility for real time evaluation of complex uneven forces on complex parts therefore having a good potential for commercialization.

The luminescence of ZnO:Ga ceramics was studied at room temperature under 270 keV electrons irradiation. The near band gap and defects related luminescence intensity independence on irradiation dose up to 9.4 x 1013 e/ cm2 as well as absence of thermostimulated luminescence within 300-600 K confirm that ZnO:Ga ceramics is radiation hard material for sub-threshold energy electron irradiation and therefore is prospective as scintillator for sub-threshold electrons detection. The near band gap luminescence peak position is at 393 nm under electron beam irradiation, and it is shifted to the long wave side relative to photoluminescence. The origin of the observed shift could be both - the difference of recharged donor-acceptor pairs created under photoexcitation and electron beam irradiation as well as contribution from host material self-absorption.

With plasma electrolytic oxidation (PEO), one can easily obtain thick (tens of microns), mechanically resilient and chemically stable oxide coating on aluminum and other valve metal alloys. The study of luminescent PEO coatings is a relatively new subfield of the already well-established coating preparation methods. In recent years, many new luminescence-based approaches have been developed, one of which is the detection of ionizing radiation of carbon-doped PEO alumina coating. This study presents an improved approach by doping the alumina coating with chromium using citric acid as an additive in the electrolyte. Trivalent chromium ions replacing aluminum in the crystalline lattice of the coating exhibit characteristic sharp lines in the luminescence spectrum. The effectiveness of different DC voltages, process times and citric acid concentrations in electrolyte were examined. The use of citric acid in the electrolyte also provides the conditions required for the formation of an energy trap in the bandgap of the material, thus opening up the possibility for the coating to be used as an ionizing radiation detector by measuring its thermoluminescence. Chromium atoms are incorporated in the coating from the Al6082 aluminum alloy itself and are not added in the electrolyte, therefore making the process much more reliable, repeatable, and environmentally friendly.

Optical information storage technology is emerging, therefore materials suitable for optical write-in and read-out are in demand. In this study the influence of boric acid addition during synthesis on the optical information storage properties of BaSi2O5:Eu material, that has been recently offered as a perspective material for this application. A thorough investigation is carried out to establish the relationship between boric acid addition, phase composition and photostimulated luminescence performance of the samples. The present work demonstrates the influence of the boric acid addition on the trapping center distribution in the material, thus leading to the improvement of photostimulated luminescence intensity. This can lead to the optimization of BaSi2O5:Eu material for optical information storage.

Mechanoluminescent materials transform mechanical energy into visible light. Phenomena could prove to be advantageous to various next-generation monitoring systems employed in the fields of security and healthcare if the intrinsic mechanisms are fully understood. Scientific efforts are mainly hindered by the lack of equipment capable of controlled mechanical deformation and simultaneous collection of light emitted by the sample. This article describes an easily constructible material testing device (508 €) with an interchangeable test fixture and an integrated load cell made from readily available mechanical components and 3D printed parts. A commercial low-cost alternative to spectroscopic apparatus (200 €) has recently become available alongside a highly capable 16-bit CMOS camera intended for low light conditions (520 €). A highly modular prototype system with an overall cost much lower than commercial alternatives that provide less functionality could enable a larger portion of scientific personnel to contribute to a novel field of research.

Abstract Many medical examinations involve ionizing radiation. Although the range of available dosimeters is rather wide, their linearity and chemical stability are limited. Recently, there has been a growing interest in new, improved dosimetric materials for emerging applications in medicine and other fields, such as sterilisation of consumer goods and medical instruments, irradiation of seeds, chemical agents and others. One of the classical dosimeters is carbon-doped alumina (Al2O3:C) – a well-established and widely used material for personal and industrial dosimeter with a range of great properties, such as high sensitivity, wide linearity range and relative ease of production and handling. However, the demand for reliable dosimeters in a high-dose range is still only partially fulfilled, and alumina doped with chromium ions (Al2O3:Cr) can be a promising candidate. In this study, we explored alumina doped with chromium porous microparticles synthesized with a sol-gel method as a possible high dose dosimeter and evaluated its thermostimulated luminescence signal, dose response with two irradiation sources and measured long-time fading. It was found that although the TSL signal was quite complex (consisting of two main peaks above room temperature) and the long-term fading was significant (around 50 % in the span of 30 days), with sufficient optimisation the material could be used as a high-dose dosimeter for X-ray and beta irradiation. Wide high dose linearity range, physical and chemical characteristics, as well as low production costs and ease of synthesis make chromium (III) doped alumina a compelling candidate for applicability in various medical and industry fields.

Dosimetry is a widespread material science field dealing with detection and quantification of ionizing radiation using electronic processes in materials. One of the main aspects that determines the performance of dosimeters is the type of defects the material contains. Crystalline lattice imperfections are formed around impurity ions, which may have a smaller or larger size, or different oxidation states compared to host ions. In this study, we show what effects Cr impurities have on the luminescent properties of alumina. Porous Al 2 O 3 : Cr microceramics synthesized using the sol-gel method showed a higher thermoluminescence response than a single crystal ruby. We have found that Cr 2 O 3 concentration of 0.2 wt% was optimal; it yielded the highest X-ray luminescence and thermostimulated luminescence readout of all studied additive concentrations added to alumina during synthesis. Our results show that Cr doped alumina could potentially be used as a promising new material for dosimetry of ionizing radiation.