المؤلفون: Suzuki, Shizuka¹ (AUTHOR), Dazai, Takuro¹ (AUTHOR), Tokunaga, Tomoharu² (AUTHOR), Yamamoto, Takahisa² (AUTHOR), Katoh, Ryuzi³ (AUTHOR), Lippmaa, Mikk⁴ (AUTHOR), Takahashi, Ryota¹ (AUTHOR) takahashi.ryota@nihon-u.ac.jp

المصدر: Journal of Applied Physics. 5/21/2024, Vol. 135 Issue 19, p1-10. 10p.

مصطلحات موضوعية: *YTTRIUM aluminum garnet, *GARNET, *KINETIC energy, *ALUMINUM films, *MOLECULAR beam epitaxy, *PULSED laser deposition, *OXIDE coating, *PHOSPHORS

مستخلص: We have investigated the He buffer gas process of moderating the kinetic energy of the pulsed laser deposition (PLD) plume during EuxY2−xO3 phosphor film growth. When using a neodymium yttrium aluminum garnet laser for PLD thin film growth, the kinetic energy of the ablation plumes can be high enough to cause the formation of point defects in the film. The buffer gas pressure is an important process parameter in PLD film growth. We find that the presence of the He buffer gas reduces the kinetic energy of the laser deposition plume through many low-angle collisions in the gas phase by a factor of 7 without reducing the deposition rate. This is because He is much lighter than any of the elements in the plume and it does not affect the composition of the oxide films. Consequently, the resputtering of the Y2O3 film surface by the plume was significantly suppressed in the presence of the He gas moderator, leading to a decrease of the defect density in the Y2O3 films. The improvement of the film quality was verified by a systematic analysis of time-resolved photoluminescence (PL) data for EuxY2−xO3 composition–gradient films. The PL lifetime and intensity of Eu0.2Y1.8O3, which shows the highest PL intensity, increased by 13.3% and 36.4%, respectively, when the He gas moderation process was used. The He buffer gas process is applicable to the PLD growth of the other oxide materials as well, where the reduction of the kinetic energy of the plume would bring the PLD process closer to the molecular beam epitaxy growth condition. [ABSTRACT FROM AUTHOR]

المؤلفون: Zhou, Chunming^1,2 (AUTHOR), Chen, Hang^1,2 (AUTHOR), Cao, Yue³ (AUTHOR), Li, Yanbin^1,2 (AUTHOR), Zhou, Tianyuan^1,2 (AUTHOR), Shi, Chaofan² (AUTHOR), Chen, Dongshun² (AUTHOR), Chen, Xu^1,2 (AUTHOR), Lin, Shenghui^1,2 (AUTHOR), Liu, Xuanchu^1,2 (AUTHOR), Kang, Jian^2,4 (AUTHOR), Shao, Cen^2,5 (AUTHOR), Strek, Wieslaw⁶ (AUTHOR), Chen, Hao^1,3 (AUTHOR), Zhang, Le^1,2,7 (AUTHOR) zhangle@jsnu.edu.cn

المصدر: Ceramics International. Jul2024, Vol. 50 Issue 14, p25908-25917. 10p.

مصطلحات موضوعية: *PHOSPHORS, *YTTRIUM aluminum garnet, *LUMINOUS flux, *SEMICONDUCTOR lasers, *POWER density, *THERMAL resistance, *SURFACE temperature

مستخلص: Phosphor converters with excellent thermal performance and high color rendering index (CRI) demonstrate vast application prospects in the field of laser diodes (LDs) lighting. Nevertheless, the significant heat accumulation within the converters and the absence of red spectral components pose challenges in achieving both a high saturation threshold and a high CRI for Y 3 Al 5 O 12 :Ce phosphor converters destined for white LDs. In this work, Mg 2 Al 4 Si 5 O 18 :Eu/Y 3 Al 5 O 12 :Ce (MAS:Eu/YAG:Ce) composite phosphor converters with excellent thermal performance and enhanced CRI were designed and fabricated for reflective laser lighting. Impressively, MAS:Eu/YAG:Ce phosphor-glass-ceramic composites (PGCC) retained a remarkable 97.8 % of the room temperature emission intensity at 150 °C. The reasons for this could be attributed to the strong thermal quenching resistance exhibited by MAS:Eu phosphors, as well as the ultra-thin glass bonding layer of about 150–200 μm. Meanwhile, by integrating the MAS:Eu/YAG:Ce PGCC with a 450 nm laser source, white LD devices operating in a remote excitation mode were fabricated. These white LDs demonstrated an improved CRI of 76 and maintained a low surface temperature of 131.7 °C under an ultra-high laser power density of 47.8 W/mm2 (laser power ∼ 4.70 W). Moreover, the maximum luminous flux and luminous efficiency of the white LDs were 484 lm and 103 lm/W, respectively. Therefore, the design of MAS:Eu/YAG:Ce composite phosphor converters offers a new approach for the development of high-power white LDs. [ABSTRACT FROM AUTHOR]

المؤلفون: Mohamed, Moushira. A.¹ (AUTHOR), Ali, Mohamed. A.¹ (AUTHOR) mohamedali@zju.edu.cn, Shaorun, Guo¹ (AUTHOR), Liu, Xiaofeng² (AUTHOR), Qiu, Jianrong¹ (AUTHOR) qjr@zju.edu.cn

المصدر: Advanced Optical Materials. 7/5/2024, Vol. 12 Issue 19, p1-9. 9p.

مصطلحات موضوعية: *YTTRIUM aluminum garnet, *INJECTION molding, *LIGHT emitting diodes, *THERMOPLASTIC composites, *SILICA nanoparticles, *GLASS

مستخلص: Phosphor‐in‐silica glass (PiSG) composite is an excellent candidate for highly stable and efficient color converter in high power white light emitting diodes (wLEDs). However, the high‐throughput fabrication of PiSG with different shapes is still challenging for current techniques. Here this study reports the manufacture of transparent PiSG based on YAG:Ce (Y3Al5O12:Ce3+) using injection molding (IM) technique. In this approach, different shapes of centimeter‐sized YAG:Ce‐PiSG pieces are fabricated by using IM of a YAG:Ce/amorphous silica nanoparticles/thermoplastic polymer composite at low temperatures (@ 150 °C) which afterward are debound (@ 600 °C) and densified (@ 1150 °C). Interestingly, the molding time to produce YAG:Ce/silica/polymer green parts is 5 s per piece, implying the capability for high‐throughput production of YAG:Ce‐PiSG. Furthermore, the as‐fabricated YAG:Ce‐PiSG exhibits high luminescence efficiency (>91%) and high chemical/thermal stabilities. Accordingly, high power wLEDs (10 W) are fabricated using the YAG:Ce‐PiSG which demonstrates high luminous efficiency of 144 lm W−1 at 50 mA, closing to that of the wLEDs fabricated by expensive YAG:Ce ceramic plate (i.e., 149 lm W−1 @ 50 mA). The work provides a facile and universal approach for industry‐scale production of PiSG that can be promising for various photonic applications. [ABSTRACT FROM AUTHOR]

المؤلفون: Li, Muzhi^1,2 (AUTHOR), Cai, Huangyue^1,2 (AUTHOR), Wang, Panpan^1,2 (AUTHOR), Cheng, Weilun^2,3 (AUTHOR), Zhang, Hanchao^2,3 (AUTHOR), Zhao, Xiaofeng^1,2 (AUTHOR) xiaofengzhao@sjtu.edu.cn, Peng, Di^1,2,3 (AUTHOR) idgnep8651@sjtu.edu.cn

المصدر: Ceramics International. Jun2024:Part B, Vol. 50 Issue 11, p19702-19708. 7p.

مصطلحات موضوعية: *YTTRIUM aluminum garnet, *GAS turbines, *HEAT treatment, *PARTIAL pressure, *HIGH temperatures, *THERMAL analysis

مستخلص: Thermal history sensors are valuable tools for thermal analysis of high-temperature components within aero-engines and gas turbines. However, most thermal history sensors have an upper temperature limit of ∼1200 °C, which is insufficient to meet the requirement of gas turbines. This study introduces a novel material for thermal history sensing capable of measuring temperatures up to 1400 °C. We show thermal history measurements based on the emission intensity ratio of a Eu3+-doped yttrium–aluminum mixture, whose luminescence characteristics undergo irreversible changes when exposed to high temperature. The primary mechanism is the decrease of the symmetry ratio owing to the phase transformation from YAG (Y 3 Al 5 O 12), YAM (Y 4 Al 2 O 9) to YAP (YAlO 3) utilizing the combination reaction of YAP induced by heat-treatment. The intensity ratio between 5D 0 →7F 1 and 5D 0 →7F 2 exhibits a monotonic decrease from 1.3 to 0.4 as the heat-treatment temperature increases from 1000 °C to 1400 °C. Moreover, we demonstrate that the irreversible change in intensity ratio after heat treatment remains insensitive to exposure time and oxygen partial pressure. Thus, the Eu3+-doped yttrium-aluminum mixture is a promising material for manufacturing high-temperature thermal history sensors. [ABSTRACT FROM AUTHOR]

المؤلفون: Sartowska, Bożena¹ (AUTHOR) b.sartowska@ichtj.waw.pl, Starosta, Wojciech¹ (AUTHOR), Sokołowski, Paweł² (AUTHOR), Wawszczak, Danuta¹ (AUTHOR), Smolik, Jerzy³ (AUTHOR)

المصدر: Nukleonika. Jun2024, Vol. 69 Issue 2, p125-128. 4p.

مصطلحات موضوعية: *YTTRIUM aluminum garnet, *ZIRCONIUM alloys, *CORROSION resistance, *PROTECTIVE coatings, *SILICON alloys, *PHYSICAL vapor deposition, *NUCLEAR fuel elements

مستخلص: Zirconium alloys are used as a cladding material for fuel elements in nuclear reactors. In the case of severe accident conditions, the possible rapid oxidation of zirconium in steam or/and air may result in intense hydrogen generation and hydrogen–oxide mixture explosion. Advanced technologies for increasing the corrosion resistance of claddings are being investigated in two directions: (a) protective coatings on Zr alloys and (b) the use of new materials for claddings. Coatings with silicon may provide a more protective barrier than the ZrO2 films formed on an alloy cladding during nuclear plant operations. These coatings may also serve as a protective barrier during high-temperature accidents. The current work aimed at developing protective coatings with silicon on zirconium alloys. Multielemental Zr–Si–Cr coatings were formed on Zry-2 alloy using the physical vapor deposition (PVD) method. Long-term oxidation tests were carried out under the following conditions: 360°C/195 bar/63 days/water-simulating PWR water. Obtained results show the protective character of formed layers. The material in the form of silicon carbide grains covered with yttrium–aluminum garnet (SiC + YAG) was prepared using the sol–gel method. The formed powder is the main component for coating formation on Zr–1Nb alloy using the method of suspension plasma spraying (SPS). [ABSTRACT FROM AUTHOR]

المؤلفون: Shen, Jie¹ (AUTHOR) lvdoutwo@126.com, Jin, Jing‐Jing² (AUTHOR), Huang, Jian‐Hua¹ (AUTHOR), Wang, Hong‐Wei¹ (AUTHOR), Shi, Lei¹ (AUTHOR)

المصدر: Journal of Cosmetic Dermatology. Jun2024, Vol. 23 Issue 6, p2022-2029. 8p.

مصطلحات موضوعية: *YTTRIUM aluminum garnet, *RADIO frequency, *ABDOMEN, *LASERS, *CARDIAC amyloidosis

مستخلص: Background: Striae distensae (SD) is a challenging cosmetic condition. Ablative fractional laser (AFL) is an effective method for treating SD. Recently, fractional radiofrequency (FRF) has been shown to be a promising treatment for SD; however, few studies have shown the differences between FRF and AFL in the treatment of SD. Aims: This study aimed to evaluate and compare the clinical efficacy and safety of bipolar FRF with 2940‐nm erbium yttrium aluminum garnet (Er:YAG) AFL in the treatment of SD. Patients/Methods: Twenty volunteers with abdominal SD were enrolled in this study. One half of the abdomen was treated with 2940‐nm Er:YAG AFL, whereas the other half was treated with bipolar FRF, with three sessions at 4‐week intervals. Photographic evaluations of clinical improvement were conducted by two independent investigators before and after treatment, and the patients provided self‐assessments. Two participants underwent three punch biopsies, one before treatment and two obtained from bilateral representative skin lesions on the abdomen 3 months following the final treatment. Results: Clinical improvements were observed in SD on both sides of the abdomen after the two treatments. Post‐treatment skin biopsies revealed increased thickness in the epidermis and dermis, and higher collagen and elastin density compared to those at the baseline. No statistically significant differences were observed in the clinical outcomes between the two treatment approaches. Conclusions: The efficacy and safety of bipolar FRF treatment are comparable to those of 2940‐nm Er:YAG AFL treatment, providing an alternative and effective treatment for SD. [ABSTRACT FROM AUTHOR]

المؤلفون: Zahra, Billel¹ (AUTHOR) billel.zahra@g.enp.edu.dz, Mekki, Hamza¹ (AUTHOR), Guerbous, Lakhdar² (AUTHOR), Boukerika, Allaoua² (AUTHOR)

المصدر: Journal of Radioanalytical & Nuclear Chemistry. Jun2024, Vol. 333 Issue 6, p2767-2776. 10p.

مصطلحات موضوعية: *YTTRIUM aluminum garnet, *NUCLEAR counters, *SCINTILLATORS, *VALUATION of real property, *DIAGNOSTIC imaging, *DETECTORS, *RADIATION

مستخلص: This study delves into investigating the influence of pH on the scintillation characteristics of YAG: Ce3+ nanoscintillators. Six sample detectors were fabricated using cerium-activated YAG powder synthesized via the sol–gel method at different pH levels. The aim is to identify the optimal pH for designing efficient radiation detectors, thus advancing radiation detection technologies. Results underscore pH's role in optimizing YAG: Ce3+ nanoscintillator performance. Synthesis at pH = 4 exhibited superior performance, with a scintillation light yield of 26384 ± 3500 ph/MeV and a fast component decay of 82 ns. These findings inform the synthesis and optimization of YAG: Ce3+ nanoscintillators, benefiting applications such as radiation detection and medical imaging. [ABSTRACT FROM AUTHOR]

المؤلفون: Yu, Bin¹ (AUTHOR), Sun, Bingheng² (AUTHOR) sunbingheng@siom.ac.cn, Fan, Jintai² (AUTHOR), Hao, Haoying² (AUTHOR), Shen, Fangliang² (AUTHOR), Wang, Jingang² (AUTHOR), Jiang, Benxue² (AUTHOR), Zhang, Long² (AUTHOR), Sun, Jun^1,3 (AUTHOR) sj@ms.xjb.ac.cn

المصدر: Journal of the American Ceramic Society. Jun2024, Vol. 107 Issue 6, p4282-4295. 14p.

مصطلحات موضوعية: *GARNET, *YTTRIUM aluminum garnet, *VALENCE fluctuations, *TRANSPARENT ceramics, *SEMICONDUCTOR lasers, *CRYSTAL defects, *IONS

مستخلص: Transition‐metal Mn2+ ion‐doped transparent ceramics (TCs) are promising color‐convertors to improve color rendition for solid‐state lighting. However, the stabilization of Mn2+ remains a challenge owing to the changeable atmosphere in the specific preparation of TC. In this work, the variations of valence states of Mn ions in typical garnet lattice host (YAG and LuAG) throughout the TC fabrication were demonstrated. By combined first principles calculation and experimental investigation, an enhanced self‐reduction of Mn ions was clarified in LuAG host, which was originated from the higher concentration of oxygen vacancy defects. Moreover, the air annealing treatment could significantly weaken and enhance the absorption of Mn2+ and Mn3+ respectively, degrading the orange–red emission peaking at 594 nm. On account of the oxidation of Mn2+ ions, a photoluminescence spectra redshift of 9 nm was observed with increasing air annealing temperature and oxygen content, owing to strengthened crystal field strength surrounding Mn2+ ions. Finally, a high color rendering index of 74.5 of resultant white laser diodes device structured by single‐phase LuAG:Ce,Mn TCs was obtained based on an efficient energy transfer process from Ce3+ to Mn2+. This study will deepen the understanding of the crystal defects inside TCs on luminescence properties, as well as inspiring more exploration on defect control to develop high performance ceramic color‐convertor. [ABSTRACT FROM AUTHOR]

المؤلفون: Liu, Huan¹ (AUTHOR), Jiang, Yu¹ (AUTHOR), Yu, Xueqing¹ (AUTHOR) 42802@hdu.edu.cn, Mao, Minmin¹ (AUTHOR), Liu, Bing¹ (AUTHOR), Lu, Zhilun^1,2 (AUTHOR) z.lu@leeds.ac.uk, Barzegar Bafrooei, Hadi¹ (AUTHOR), He, Shuang³ (AUTHOR), Ren, Yingjie³ (AUTHOR), Taheri-nassaj, Ehsan⁴ (AUTHOR), Song, Kaixin¹ (AUTHOR) kxsong@hdu.edu.cn

المصدر: Journal of the European Ceramic Society. Jun2024, Vol. 44 Issue 6, p3895-3902. 8p.

مصطلحات موضوعية: *CERAMICS, *YTTRIUM aluminum garnet, *DIELECTRIC properties, *ANTENNAS (Electronics), *RADIO technology, *PERMITTIVITY

مستخلص: In garnet phase ceramics Y 2.9 M 0.1 Al 4.9 Si 0.1 O 12 (M = Mg2+, Co2+, Zn2+, Mn2+, Ca2+, Sr2+, Ba2+), rattling effects occur when M = Mg2+, Co2+, Zn2+, Mn2+ ions with smaller ionic radius (<1Å) occupy the dodecahedron lattice lattices. This results in an abnormally high dielectric constant, in contrast to the larger ionic radius (>1 Å) of M = Ca2+, Sr2+ and Ba2+, which deviate from the theoretical values calculated using the Clausius-Mosotti formula according to each ion's polarizability. The optimal microwave dielectric properties for Y 2.9 Mg 0.1 Al 4.9 Si 0.1 O 12 was obtained by sintering at 1575 °C for 5 h (Q × f = 51,382 GHz, ε r = 9.74, and τ f = −30.12 ppm/°C). Additionally, a thermal stable Y 2.9 Mg 0.1 Al 4.9 Si 0.1 O 12 -6 wt%TiO 2 composite ceramic was developed. Based on this composite, a Wifi6E/7 patch antenna operating at 6.3 GHz and a millimeter-wave resonant antenna functioning at 27.1 GHz were designed and validated. This indicates the potential application prospects of garnet ceramics in 5G/6G radio communication technologies. [ABSTRACT FROM AUTHOR]

المؤلفون: Dai, Ru¹ (AUTHOR), Yang, Xiaoshuang¹ (AUTHOR), Su, Yiping^1,2 (AUTHOR), Wu, Xianjie¹ (AUTHOR) wuxianjie@zju.edu.cn

المصدر: Lasers in Medical Science. 5/10/2024, Vol. 39 Issue 1, p1-9. 9p.

مصطلحات موضوعية: *YAG lasers, *YTTRIUM aluminum garnet, *ALOPECIA areata, *BALDNESS, *MINOXIDIL, *LIKERT scale

مستخلص: Laser sources have established their potential effect in inducing hair regrowth. No large cohort study has evaluated the effect of ablative fractional 2940-nm erbium yttrium aluminum garnet (Er: YAG) laser in the treatment of androgenetic alopecia (AGA). To investigate the efficacy and safety of the ablative fractional 2940-nm Er: YAG laser in combination with medication therapy for the treatment of AGA. We performed a retrospective study between first July 2021 to 30th December 2021. All included patients received oral finasteride and topical minoxidil, or combined with six sessions of Er: YAG laser at 2-week intervals. Patients were divided into medication or combined therapy groups. The efficacy of the two therapies was evaluated by the investigator's Global Assessment (IGA) scores and the patient's Likert satisfaction scale at week 12 and week 24. Changes in total, terminal and villous hair count, total and terminal hair diameter, and AGA grade were also recorded. Adverse events were evaluated at each follow-up. A total of 192 male patients with AGA were included, including 67 receiving combination treatment, and 125 receiving medication treatment. At week 24, the combination treatment afforded superior outcomes in the IGA score, patient's global assessment, total and terminal hair counts, and diameters (all P<0.05). No severe adverse events were reported in both groups. The combined therapy of ablative fractional Er: YAG laser and medication was superior in treating male AGA than single medication therapy without serious adverse effects. [ABSTRACT FROM AUTHOR]