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Near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) are newly emergent broadband light sources for miniaturizing optical systems like spectrometers. However, traditional converters with NIR phosphors encapsulated by organic resins suffer from low external quantum efficiency (EQE), strong thermal quenching as well as low thermal conductivity, thus limiting the device efficiency and output power. Through pressureless crystallization from the designed aluminosilicate glasses, here broadband Near‐infrared (NIR) emitting translucent ceramics are developed with high EQE (59.5%) and excellent thermal stability (<10% intensity loss and negligible variation of emission profile at 150 °C) to serve as all‐inorganic visible‐to‐NIR converters. A high‐performance NIR phosphor‐converted light emitting diodes is further demonstrated with a record NIR photoelectric efficiency (output power) of 21.2% (62.6 mW) at 100 mA and a luminescence saturation threshold up to 184 W cm−2. The results can substantially expand the applications of pc‐LEDs, and may open up new opportunity to design efficient broadband emitting materials. [ABSTRACT FROM AUTHOR]

The damping parameter ${\alpha }_{\mathrm{ FM}}$ in ferrimagnets defined according to the conventional practice for ferromagnets is known to be strongly temperature-dependent and diverge at the angular momentum compensation temperature, where the net angular momentum vanishes. However, recent theoretical and experimental developments on ferrimagnetic metals suggest that the damping parameter can be defined in such a way, which we denote by ${\alpha }_{\mathrm{ FiM}}$ , that it is free of the diverging anomaly at the angular momentum compensation point and is little dependent on temperature. To further understand the temperature dependence of the damping parameter in ferrimagnets, we analyze several datasets from literature for a ferrimagnetic insulator, gadolinium iron garnet, by using the two different definitions of the damping parameter. Using two methods to estimate the individual sublattice magnetizations, which yield results consistent with each other, we find that in all the used datasets, the damping parameter ${\alpha }_{\mathrm{ FiM}}$ does not increase at the angular compensation temperature and shows no anomaly, whereas the conventionally defined ${\alpha }_{\mathrm{ FM}}$ is strongly dependent on the temperature. [ABSTRACT FROM AUTHOR]

The electromagnetic (EM) properties of shielded gyromagnetic spheres are characterized with the aid of an electrodynamic model formulated for the transverse electric (TE) modes of an isotropic sphere, in a similar way as dielectric resonators are commonly analyzed. Broadband characteristics of geometric and energy filling factors are presented. A new measure of the magnetic loss tangent is introduced which is positive despite the intrinsic permeability of the gyromagnetic medium being negative, where existing definitions yield a non-physical negative value. The sample size dependence of those quantities is also assessed. The conclusions from the analysis are applied to investigate and de-embed ferromagnetic linewidth errors which can occur in broadband measurements of magnetic garnet spheres. Magnetic anisotropy fields and the gyromagnetic $g$ -factor are also estimated from the measurement data. Experiments were performed in a two-port subwavelength cavity, covering a frequency range of up to 28 GHz. Additionally, two-port rectangular resonant cavity linewidth measurements at a few modes have been conducted. Good agreement between the two methods is found if the systematic error is accounted for. [ABSTRACT FROM AUTHOR]

The insulating nature and the low intrinsic damping of rare earth iron garnets made them the material of choice for spintronic research. While yttrium iron garnet (YIG) thin films are well studied and especially known for their ultralow Gilbert damping parameter, recently other rare earth iron garnet (RIG) thin films with more complex magnetic structures have gained interest. Tunable magnetic properties like the magnetic compensation temperature or perpendicular magnetic anisotropy (PMA) are hereby of great interest for the implementation in spintronic devices. In this regard, calculations predict PMA which can be induced by magnetoelastic anisotropy for the RIGs, depending on the substrate choice and subsequent film strain. We have therefore investigated the influence of lattice mismatch provided by various garnet substrates and film stoichiometry on the structural and magnetic properties of gadolinium iron garnet (GdIG) thin films with thicknesses between 13 and 218 nm. Epitaxial, single-crystalline films exhibiting smooth interfaces were prepared by pulsed laser deposition at elevated temperatures. PMA is obtained for GdIG thin films grown under tensile in-plane strain on Gd3Sc2Ga3O12 (GSGG) substrates. Furthermore, a thickness series reveals a slow structural relaxation and PMA even for 218 nm thick GdIG films. In contrast, slightly off-stoichiometric films show a reduction or even loss in PMA. All GdIG films exhibit a magnetic compensation point in the range between 210–260 K, which is lower than for bulk (286 K). In addition, a temperature dependent spin reorientation transition was observed for GdIG/GSGG samples. Therefore, GdIG films provide tunable magnetic properties controllable by film strain, stoichiometry, and temperature, which will be beneficial for further research in the related fields of magnonics and spintronics. [ABSTRACT FROM AUTHOR]

We introduce a new chamfering paradigm, locally connecting pixels to produce path distances that approximate Euclidean space by building a small network (a replacement product) inside each pixel. These “ RE-grid graphs” maintain near-Euclidean polygonal distance contours even in noisy data sets, making them useful tools for approximation when exact numerical solutions are unobtainable or impractical. The RE-grid graph creates a modular global architecture with lower pixel-to-pixel valency and simplified topology at the cost of increased computational complexity due to its internal structure. We present an introduction to chamfering replacement products with a number of case study examples to demonstrate the potential of these graphs for path-finding in high frequency and low resolution image spaces which motivate further study. Possible future applications include morphology, watershed segmentation, halftoning, neural network design, anisotropic image processing, image skeletonization, dendritic shaping, and cellular automata. [ABSTRACT FROM AUTHOR]

This paper presents a brief review of the state-of-the-art in the field of the preparation and characterization of the most widespread types of ferrites: ferrites with the spinel structure, hexaferrites, ferrites with the garnet structure, and orthoferrites. The present review is concerned primarily with advances in the synthesis and characterization of ferrites with various structures in the past two years (2020 and 2021). We compare available data on the feasibility of replacing trivalent Fe atoms by other atoms and discuss potential applications of ferrite solid solutions. The present results make it possible to identify promising directions of the development of this area of research and the associated current problems. [ABSTRACT FROM AUTHOR]

Rare‐earth iron garnets (REIG) have recently become the materials platform of choice for spintronic studies on ferrimagnetic insulators. However, thus far the materials studied have mainly been REIG with a single rare earth species such as thulium, yttrium, or terbium iron garnets. In this study, magnetometry, ferromagnetic resonance, and magneto‐optical Kerr effect imaging is used to explore the continuous variation of magnetic properties as a function of composition for YxTm3−x iron garnet (YxTm3−xIG) thin films grown by pulsed laser deposition on gadolinium gallium garnet substrates. It is reported that the tunability of the magnetic anisotropy energy, with full control achieved over the type of anisotropy (from perpendicular, to isotropic, to an in‐plane easy axis) on the same substrate. In addition, a nonmonotonic composition‐dependent anisotropy term is reported, which is ascribed to growth‐induced anisotropy similar to what is reported in garnet thin films grown by liquid‐phase epitaxy. Ferromagnetic resonance shows linear variation of the damping and the g‐factor across the composition range, consistent with prior theoretical work. Domain imaging reveals differences in reversal modes, remanant states, and domain sizes in YxTm3−x iron‐garnet thin films as a function of anisotropy. [ABSTRACT FROM AUTHOR]

This work concerns the down- and up-conversion properties of microcrystalline samples of Pr3+ doped (Lu,Y)3(Al,Ga)5O12. In order to figure out a relation between the down- and up-conversion efficiency, the optical properties involved in the up-conversion process were observed in more detail by excitation and emission measurements, under X-ray, VUV, UV-C, and blue light excitation. The phase purity was determined by using X-ray powder diffraction and diffused reflection measurements as well as time and temperature dependent measurements were performed. In addition, Al3+ was substituted within 20% steps by Ga3+ and some investigation on the change in the optical properties with increasing Ga3+ concentration was made.

Single-crystalline films (SCFs) of the LuAG: Ce garnet grown using the liquid-phase epitaxy method onto YAG single-crystal (SC) substrates were investigated for possible applications as composite thermoluminescent (TL) detectors. Such detectors may help to register the different components of ionizing radiation fields with various penetration depths, e.g., heavy charged particles and gamma or beta rays. It was found that the TL signal of LuAG: Ce SCF sufficiently differs from that of the YAG substrate concerning both the temperature and wavelength of emissions. Furthermore, even by analyzing TL glow curves, it was possible to distinguish the difference between weakly and deeply penetrating types of radiation. Within a test involving the exposure of detectors with the mixed alpha/beta radiations, the doses of both components were determined with an accuracy of a few percent.

In this study, the infrared optically stimulated luminescence (IRSL) of single crystals of Ce3+ doped yttrium aluminum garnet (YAG) was investigated for the first time. It was found that infrared stimulation of these crystals, following previous exposure to beta radiation, produces a strong luminescence signal. The highest luminescence efficiency was exhibited by the YAG crystal with 0.1% of Ce. With this crystal, it was possible to measure as low doses as 0.1 mGy. Moreover, IRSL is mainly related to the TL peak at a relatively high temperature of c.a. 175 °C, which leads to quite good stability of the signal in time. These properties create good prospects for potential applications of YAG:Ce in dosimetric radiation measurements

Garnet-inlaid metalwork was an emblem of elite culture in the early medieval North Sea world. This study compares three Anglo-Saxon garnet-inlaid brooches that are exceptionally similar in design and appearance. All three date to the seventh century, a period that saw the emergence of leading families that used such deluxe dress items to enhance their political position. The central hypothesis explored here is that the brooches were produced by the same, or by closely linked, goldsmiths working under the patronage of such a family. Integrated analysis was conducted using microscopy, CT scans, XRF and XRD, in part to establish whether the garnets used came from the same or different sources. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) phosphor‐converted (pc) light‐emitting diode (LED) is a promising next‐generation tiny light source for smart and broadband NIR spectroscopy technology. However, NIR phosphors suffer from challenges in terms of low efficiency and thermal stability. Herein, by selecting a host with large bandgap and weakening the coupling effect to Cr3+, the novel CaLu2Mg2Si3O12:Cr3+ (CLMSG:Cr3+) NIR phosphor is discovered that has an external quantum efficiency of 20.7% and high thermal stability (92.1%@100 °C). Under ≈450 nm excitation, CLMSG:Cr3+ shows broad NIR emission from 650 to 900 nm with a band width of ≈120 nm. The fabricated tiny pcLED demonstrates bright NIR light (34.75 mW@100 mA) with photoelectric efficiency of 11.6%. [ABSTRACT FROM AUTHOR]

Large‐sized Gd3Al2.3Ga2.7O12:Ce single crystals are grown by the Czochralski method. The distribution of Al and Ga at octahedral (oct‐, 6‐oxygen‐coordinated) and tetrahedral (tet‐, 4‐oxygen‐coordinated) sites in the crystal is studied. Rietveld refinement is used to analyze the site occupation of Al and Ga. The results show that Ga ions with a larger radius than Al ions prefer to occupy the more compact tetrahedral sites. Density functional theory calculations show that the energy for a Ga ion at the tetrahedral site is lower than that at the octahedral site in the Gd3Al5O12 crystal, whereas the case for Al occupation in the Gd3Ga5O12 crystal is opposite. Slater rules are used to estimate the effective charge number of different ions, and the distribution of coordination ions around the octahedral and tetrahedral sites is analyzed. Then, the interaction between ions is simplified and the repulsive energy between Al/Ga and the coordination ions is calculated, which could provide reasonable understanding on the abnormal occupation. In addition, the occupation of Sc in Gd/Y garnet systems is also discussed using this method. [ABSTRACT FROM AUTHOR]

The development of a novel composite phosphor converter based on single‐crystalline films of Tb3Al5O12:Ce garnet and Y3Al5O12:Ce single‐crystal substrate is reported. The liquid phase epitaxy growth method is chosen for the fabrication of the Tb3Al5O12:Ce/Y3Al5O12:Ce epitaxial structures with excellent photoconversion properties for application in white light‐emitting diodes (LEDs). The influence of Ce3+ concentration and thickness of Y3Al5O12:Ce substrate as well as the thickness of Tb3Al5O12:Ce films on the photoconversion properties is investigated for the construction of warm white LEDs prototypes based on the developed composite phosphor converters. [ABSTRACT FROM AUTHOR]

We introduce a new chamfering paradigm, locally connecting pixels to produce path distances that approximate Euclidean space by building a small network (a replacement product) inside each pixel. These “ $RE$ -grid graphs” maintain near-Euclidean polygonal distance contours even in noisy data sets, making them useful tools for approximation when exact numerical solutions are unobtainable or impractical. The $RE$ -grid graph creates a modular global architecture with lower pixel-to-pixel valency and simplified topology at the cost of increased computational complexity due to its internal structure. We present an introduction to chamfering replacement products with a number of case study examples to demonstrate the potential of these graphs for path-finding in high frequency and low resolution image spaces which motivate further study. Possible future applications include morphology, watershed segmentation, halftoning, neural network design, anisotropic image processing, image skeletonization, dendritic shaping, and cellular automata. [ABSTRACT FROM AUTHOR]

The luminescence efficiency of Ce3+ in garnet phosphors is among the most stable for luminescent materials. Still, it has been observed to be reduced at high incident blue flux (known as droop) due to nonlinear processes caused by the high lumen density inside the materials. Herein, it is shown that in the case of Ce3+‐doped garnet concentrator rods, the droop can be explained by excited‐state absorption (ESA) of mainly green Ce3+ luminescence light that is trapped inside the rods. ESA spectroscopy and thermally stimulated luminescence (TSL) measurements show that electrons are promoted from the 5d1 excited state of Ce3+ to the conduction band by ESA and may be either captured by traps or may recombine with Ce4+ sites to give excited Ce3+ ions giving rise to luminescence. Therefore, the droop depends on the concentration of Ce4+ ions present, which can be influenced and optimized by varying the processing conditions of the samples. Guided by these results, a model is developed that describes the optical processes. It is used to analyze the observed droop behavior in block‐shaped samples with and without extraction optics.

The paper addresses the development of composite scintillation materials providing simultaneous real-time monitoring of different types of ionizing radiation (α-, β-particles, γ-rays) in mixed fluxes of particles and quanta. The detectors are based on composite heavy oxide scintillators consisting of a thin single-crystalline film and a bulk single-crystal substrate. The film and substrate respond to certain types of ionizing particles, forming together an all-in-one composite scintillator capable of distinguishing the type of radiation through the different time characteristics of the scintillation response. Here, we report the structure, composition, and scintillation properties under different ionizing radiations of (Lu,Gd,Tb)3(Al,Ga)5O12:Ce films deposited using liquid phase epitaxy onto Gd3(Al1−xGax)5O12:Ce (GAGG:Ce) single-crystal substrates. The most promising compositions with the highest light yields and the largest differences in scintillation decay timing under irradiation with α-, β-particles, and γ-rays were selected. Such detectors are promising for environmental security purposes, medical tomography, and other radiation detection applications.

[Display omitted] • The iron-containing high-entropy garnets are synthesized for the first time. • (Dy,Er,Gd,Ho,Y) 3 Fe 5 O 12 and (Dy,Gd,Ho,Sm,Y) 3 Fe 5 O 12 exhibit excellent stability. • The electrical behavior differs significantly from the conventional garnets. • The Raman and Mossbauer spectra indicate distorted character of the lattice. High-entropy, iron-containing, garnet-structured oxides with (Dy,Er,Gd,Ho,Y) 3 Fe 5 O 12 and (Dy,Gd,Ho,Sm,Y) 3 Fe 5 O 12 compositions are synthesized for the first time. A modified Pechini method followed by calcination at 700 °C and sintering at 1300 °C enables obtaining single-phase, homogenous materials of cubic structure with Ia- 3 d symmetry. High-temperature in-situ X-ray diffraction studies show excellent phase stability of the garnets, as well as moderate thermal expansion coefficient, ca. 11·10−6 K-1 in 25−1000 °C temperature range. Raman spectroscopy measurements indicate the presence of local distortion of structural polyhedra, likely associated with the high-entropy effect. The collected Mossbauer spectra confirm distorted character of the lattice. Influenced by the presence of Fe3+ in locally distorted octahedra and tetrahedra, the electrical conduction at low temperatures of both oxides remains much lower comparing to Y 3 Fe 5 O 12 (yttrium iron garnet - YIG), as well as to other rare-earth garnets up to 600 °C, where it reaches value similar to YIG. [ABSTRACT FROM AUTHOR]

A recent paper devoted to unusual fine-scale tubular tunnels found in pyrope and almandine garnets suggested that the 5 to 100 µm diameter tunnels were produced by an endolithic organism that is able to chemically dissolve and penetrate the mineral, perhaps in search of nutrients. The hypothesized microbial boring of the garnets was based on the finding of endolithic remains in the tunnels, but boring alone does not adequately explain the linear, highly aligned or occasionally branched tunnels that have been imaged. We have prepared this short Letter, in the spirit of Occam's Razor, to highlight the very probable role that dislocations play in the creation of such tunnels by preferential etching of a dislocation-rich deformation microstructure. The geometrical features of the tunnels possess all the characteristics of classical dislocation substructures that have been observed in natural and synthetic garnets. [ABSTRACT FROM AUTHOR]

The cell parameters of synthetic pyrope were measured in the temperature range 100–630 K by the X-ray powder diffraction method. Interpolation and extrapolation of the experimental data from 50 to 2000 K were performed by the procedure based on the Debye–Mie–Gruneisen theory of solid body. Temperature dependencies of molar volumes and coefficients of volume thermal expansion were determined. The Gruneisen coefficient and Debye temperature were calculated. Heat capacity, its behavior in accordance with temperature and elastic parameters were evaluated to 2000 K. [ABSTRACT FROM AUTHOR]

The development of innovative high-power lighting sources is urgently required to design and investigate the new high structural quality and high-temperature stable converters in the form of single crystals and single crystalline films. This research deals with the growth and investigation of structural, luminescence, and photoconversion properties (color coordinates, color temperature and color rendering index) of the single crystalline films of Ce3+ doped (Lu, Y, Tb, Gd) 3 Al 5 O 12 garnets, grown using the Liquid Phase Epitaxy method onto undoped Y 3 Al 5 O 12 substrates. The combination of Ce3+ doped Lu 3 Al 5 O 12 , Y 3 Al 5 O 12 , Tb 3 Al 5 O 12 , Gd 2.9 Lu 0.1 Al 5 O 12 film converter with respective thickness with commercial blue LED allows for obtaining green-yellow-orange-emitting pc-WLEDs. The application of the mentioned film converters results in the formation of four basic trends on the color diagram depending on the thickness of the converter. • TThe study addresses the urgent demand for high-power lighting by investigating single crystalline film converters with superior structural and thermal properties. • The LPE technique is employed to grow garnet films on undoped YAG substrates. • The research analyzes the structural, luminescent, and photoconversion properties of (Lu, Y, Tb, Gd)AG:Ce films. • By combining converters and blue LEDs, the study successfully produces pc-WLEDs with green, yellow, and orange tints. • By varying converter thickness, the researchers reveal four distinct color trends on the diagram. [ABSTRACT FROM AUTHOR]

High-entropy garnet crystal structure compounds with novel chemical compositions (Y 3-x-y-z Ca x Li y Ln z Ga 5-m Al m O 12) (Ln – Ce, Eu, Tb) have been synthesized by an aqueous sol-gel method. The multinary substitution of yttrium by calcium, lithium and lanthanide element (cerium, europium and terbium) effects in these gallium/aluminium garnets have been investigated. The intermediates and synthesized end products were characterized by thermal analysis (TG/DTG/DSC), powder X-ray diffraction analysis (XRD), FT-IR spectroscopy and scanning electron microscopy (SEM). The different effects of multinary substitution with calcium, lithium and lanthanide ions in Y 3-x-y-z Ca x Li y Ln z Ga 5-m Al m O 12 samples in comparison with single-metal substitution cases were determined from the results of XRD analysis. The XRD patterns of these samples clearly showed that single phase cubic structure garnets have been synthesized at low substitutional level of yttrium by calcium, lithium and lanthanide element (cerium, europium and terbium). The luminescent properties of (Y 3-x-y-z Ca x Li y Ln z Ga 5-m Al m O 12) (Ln – Ce, Eu, Tb) garnets were also investigated. • Substituted (Y 3-x-y-z Ca x Li y Ln z Ga 5-m Al m O 12) garnets have been synthesized by sol-gel method. • The substitution effect of the Ce, Eu, Tb lanthanides in mixed-metal garnets was investigated. • The substitutional level depends very much on the nature and amount of introduced elements. • Different effects of multinary substitution with calcium, lithium and lanthanides were observed. • The luminescent properties of novel garnets were also investigated. [ABSTRACT FROM AUTHOR]

We present a comparative study of two Lu-based oxide ceramics doped with Yb3+ ions, namely Yb:Lu 3 Al 5 O 12 (garnet) and Yb:Lu 2 O 3 (sesquioxide), promising for thin-disk lasers. The ceramics are fabricated using nanopowders of 3.6 at.% Yb:Lu 2 O 3 and Al 2 O 3 produced by laser ablation: Yb:Lu 3 Al 5 O 12 – by vacuum sintering at 1800 °C for 5 h with the addition of 1 wt% TEOS as a sintering aid, and Yb:Lu 2 O 3 – by vacuum pre-sintering at 1250 °C for 2 h followed by Hot Isostatic Pressing at 1400 °C for 2 h under Ar gas pressure of 207 MPa. The comparison includes the structure, Raman spectra, transmission, optical spectroscopy and laser operation. The crystal-field splitting of Yb3+ multiplets is revealed for Lu 3 Al 5 O 12. A continuous-wave (CW) Yb:Lu 3 Al 5 O 12 ceramic microchip laser generates 5.65 W at 1031.1 nm with a slope efficiency of 67.2%. In the quasi-CW regime, the peak power is scaled up to 8.83 W. The power scaling for the Yb:Lu 2 O 3 ceramic laser is limited by losses originating from residual coloration and inferior thermal behavior. [ABSTRACT FROM AUTHOR]

Two novel garnet-type ceramics Ca3MZrGe3O12 (M = Co and Zn) with pure phase were prepared through a solid-state reaction method. Structure–property relationships were studied by the Rietveld refinement and Raman spectra. The appearance of two weak symmetric stretching vibrational peaks in Ca3ZnZrGe3O12 might be due to the lower ordering. Higher Q × f value in Co-analogue was related to the larger packing fraction and the lower FWHM of A1g mode. The smaller oxygen bond valence in Ca3CoZrGe3O12 indicates a smaller τf value. At the optimized sintering temperature of 1280 °C, Ca3CoZrGe3O12 shows desirable microwave dielectric properties with εr of 10.37, Q × f value of 60,100 GHz, and τf value of −28.5 ppm/oC. The Ca3ZnZrGe3O12 ceramic sintered at 1200 °C has the best microwave dielectric properties with εr of 10.48, Q × f value of 49,700 GHz, and τf value of −35.8 ppm/oC. [ABSTRACT FROM AUTHOR]

This paper presents LA-ICP-MS data for garnets from the Rudnik skarn deposit (Serbia), which range from Grs45--58Adr40--52Alm2--3 in the core and Adr70--97Grs2--29Sps1 in the rim displaying anisotropy and zoning. In spite of wide compositional variations the garnets near the end-member of andradite (Adr > 90) are generally isotropic. Fe-rich rims exhibit LREE depletion and flat HREE pattern with weak negative Eu anomaly, including higher As and W contents. On the other side, the Fe-poorer core shows flat REE pattern without any significant enrichment or depletion of REE, except higher amounts of trace elements, such as U, Th and Zr. Presence of sulphide minerals indicates reduction conditions and Eu divalent state. Different REE behaviour is conditioned by Eu2+ in reduction conditions. The observed variations in optical features and garnet chemistry are the results of their two-stage evolution. The first stage and period of garnet growth is probably buffered by mineral dissolution and reactions in the country rock. The second stage is related to hydrothermal activity when W and Fe were brought into the system probably by a boiling process in the volcanic event in the late Oligocene 23.9 Ma. [ABSTRACT FROM AUTHOR]

This manuscript summarizes recent results on the development of composite luminescent materials based on the single-crystalline films and single crystals of simple and mixed garnet compounds obtained by the liquid-phase epitaxy growth method. Such composite materials can be applied as scintillating and thermoluminescent (TL) detectors for radiation monitoring of mixed ionization fluxes, as well as scintillation screens in the microimaging techniques. The film and crystal parts of composite detectors were fabricated from efficient scintillation/TL materials based on Ce3+-, Pr3+-, and Sc3+-doped Lu3Al5O12 garnets, as well as Ce3+-doped Gd3−xAxAl5−yGayO12 mixed garnets, where A = Lu or Tb; x = 0–1; y = 2–3 with significantly different scintillation decay or positions of the main peaks in their TL glow curves. This work also summarizes the results of optical study of films, crystals, and epitaxial structures of these garnet compounds using absorption, cathodoluminescence, and photoluminescence. The scintillation and TL properties of the developed materials under α- and β-particles and γ-quanta excitations were studied as well. The most efficient variants of the composite scintillation and TL detectors for monitoring of composition of mixed beams of ionizing radiation were selected based on the results of this complex study.

Thin films of ferrimagnetic iron garnets can exhibit useful magnetic properties, including perpendicular magnetic anisotropy (PMA) and high domain wall velocities. In particular, bismuth-substituted yttrium iron garnet (BiYIG) films grown on garnet substrates have a low Gilbert damping but zero Dzyaloshinskii-Moriya interaction (DMI), whereas thulium iron garnet (TmIG) films have higher damping but a nonzero DMI. We report the damping and DMI of thulium-substituted BiYIG (BiYTmIG) and TmIG|BiYIG bilayer thin films deposited on (111) substituted gadolinium gallium garnet and neodymium gallium garnet (NGG) substrates. The films are epitaxial and exhibit PMA. BiYIG|TmIG bilayers have a damping value that is an order of magnitude lower than that of TmIG, and BiYIG|TmIG|NGG have DMI of 0.0145 ± 0.0011 mJ/m 2 , similar to that of TmIG|NGG. The bilayer therefore provides a combination of DMI and moderate damping, useful for the development of high-speed spin orbit torque-driven devices.

YAG:Ce and LuAG:Ce ceramics are widely used as scintillator materials that convert high-energy radiation into visible light. For the practical application of such compounds, short decay times are a necessity. One way of shortening the existing decay times even more is to change the local environment of emitting ions by means of doping the matrix with additional elements, for example, boron or magnesium. Furthermore, boron ions also can help absorb gamma rays more efficiently, therefore improving overall applicability. Due to the aforementioned reasons, YAG and LuAG ceramics doped with cerium, boron, and magnesium were synthesized. Initial amorphous powders have been obtained by means of sol-gel synthesis and pressed into pellets under isostatic pressure and finally calcinated to form crystalline ceramics. The effects of boron and magnesium doping on the morphological, structural, and luminescence properties were investigated. The key results showed that doping with boron has indeed shortened the decay times of the garnet pellets. Overall, boron doping of ceramics is a relatively new research area; however, it is rather promising as it helps both to improve the luminescence properties and to increase particle growth rate., (© 2024 John Wiley & Sons Ltd.)

This paper reports the structural and magnetic properties of a series of Y 3 Fe 5-x Ni x O 12 (x = 0, 0.05, 0.1, and 0.2) nanopowders synthesized by the citrate combustion method. We have discussed the change in different properties with the variation in calcination temperatures as well as the Ni ion substitution in yttrium iron garnet. X-ray diffraction study confirmed the desired garnet phase formation in all the calcined powders, and the crystallinity improved with an increase in calcination temperature. The crystallite sizes were observed in the range 47–52 nm and 84–94 nm for the samples calcined at 800 and 1000 °C, respectively. Scanning electron micrographs confirmed that the grains were in the nanometre range (132–170 nm) at 800 °C and increased (351–363 nm) at 1000 °C. Larger grains at high calcination temperature resulted in the enhanced saturation magnetization and a decrease in coercivity. Curie temperature (T c) was observed in the range 558–560 K for all the calcined Y 3 Fe 5-x Ni x O 12 samples. Nickel substitution for iron sites in Y 3 Fe 5-x Ni x O 12 decreased the saturation magnetization and enhanced the coercivity. This could be related to the substitution of Ni ions for tetrahedral iron sites, which changed the magnetic exchange interactions of different lattice sites. The magnetic anisotropy constant (K) increases with the enhancement of calcination temperature, whereas it decreases with nickel ion substitution in Y 3 Fe 5-x Ni x O 12. This study suggests that the structural and magnetic properties can be tuned by Ni substitution for the Fe ions in Y 3 Fe 5 O 12 garnets at different calcination temperatures, which make them promising candidates for various technological applications. [ABSTRACT FROM AUTHOR]

Experiments for heavy rare-earth iron garnets Ho 3 Fe 5 O 12 and Er 3 Fe 5 O 12 show a compensation effect characterized by a near zero magnetization at 134 K and 80 K, respectively. The magnetic entropy change calculated according to the Maxwell's relation is shown to be positive and negative, indicating both normal and inverse magnetocaloric effects exist in the sample. The critical temperature (134 K for Ho 3 Fe 5 O 12 , 80 K for Er 3 Fe 5 O 12) of the two types of magnetocaloric effect occurs at almost the same temperature as the compensation point. However, the compensation effect is attributed to the multiple exchange interactions among the octahedral sites Fe3+, the tetrahedral sites Fe3+ and the dodecahedral sites R3+, while the reversal of the magnetocaloric effect is originated from the spin reorientation. The maximum magnetic entropy change of the normal magnetocaloric effect is 4.72 J kg−1 K−1 for Ho 3 Fe 5 O 12 at 34 K and 4.94 J kg−1 K−1 for Er 3 Fe 5 O 12 at 24 K, respectively. Moreover, all the positive slopes of basic Arrott plots suggest only the second-order phase transition existing in Ho 3 Fe 5 O 12 and Er 3 Fe 5 O 12. [ABSTRACT FROM AUTHOR]

This article outlines the main results of a research and development cooperation between Philips Research Eindhoven; Peter the Great St. Petersburg Polytechnic University; Ioffe Institute, St. Petersburg; Utrecht University; and Philips Healthcare. It reviews the properties of garnet ceramics in the (Lu,Gd)3(Ga,Al)5O12:Ce system for medical imaging, especially time-of-flight positron emission tomography (PET). Thermally stimulated luminescence (TSL) peaks are attributed to impurities, verified by intentional codoping of samples. A lately developed method allows extraction of carrier lifetimes, thermal trap depths, and frequency factors from TSL and afterglow measurements. A detailed analysis reveals the presence of a distribution of trap depths, allowing a more accurate afterglow modeling. Activation energies of thermal ionization and trap depths obtained from TSL show the influence of Ga/Al substitution on thermal quenching and on trap position. The resulting nonmonotonic dependence of the conduction band edge with Ga content in (Lu,Gd) garnets is consistent with earlier predictions. Shallow traps determine both signal decay and short-term afterglow. The impact of signal height, rise, and decay times on coincidence resolving time and further on PET image quality is described by analytical models. [ABSTRACT FROM AUTHOR]

Garnet‐based solid‐state electrolytes (SSEs) are attractive for solid‐state lithium metal batteries due to their wide electrochemical window, high conductivity, and excellent stability against lithium metal. However, the risk of short‐circuit encumbers the cycle life and capacity of garnet‐based solid‐state batteries without clear reason or mechanism. Here, reversible short‐circuit behavior in the garnet‐based solid‐state batteries, which differs from the short‐circuit in liquid cells, is reported for the first time. In situ neutron depth profiling is adopted to quantitatively measure Li transport, which helps forecast and confirm the reversible nature of the short‐circuit in garnet‐based batteries. A real‐time Li accumulation monitoring system of NMC//CNT/garnet/Li cell is designed to reveal the Li dendrite formation mechanism. The voltage drops of the CNT monitoring electrode during the charging process indicate the formation of Li dendrites inside the garnet bulk, while the smooth voltage profile during the discharging process demonstrates the disappearance of the short‐circuit. This is the first confirmation of short‐circuit behavior that provides clarification of the Li dendrite formation mechanism in garnet‐based solid‐state batteries, which is shown to be a reversible process caused by the low ionic conductivity and non‐negligible electronic conductivity of garnet SSEs. [ABSTRACT FROM AUTHOR]

The cost of the rare-earth metal cerium means that preparation of YAG:Ce is expensive. To overcome this, the garnet could partially be replaced by cheaper alternatives, while retaining the original properties of YAG: Ce. Composites with different polymers such as polyethylene glycol diacrylate (M280) and dipentaerythrityl hexaacrylate (M600) were therefore studied. YAG:Ce and boron nitride were added into the polymer matrix in order to obtain composites with enhanced thermal conductivity, necessary for high-optical-density applications. The physical properties of the composites were measured by using XRD, DSC, SEM, and NMR, and the most important characteristics for LED materials such as emission, excitation, decay time and quantum efficiency were analyzed. An LED prototype was developed to test and demonstrate the composites for practical applications. That developed device exhibited optical properties very close to those comprising a commercial garnet prototype, which was also developed for comparison. The main advantage of the proposed technology is that by using 2 time less the amount of YAG: Ce, almost the same light output was obtained compared to commercial phosphors. [ABSTRACT FROM AUTHOR]