• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.6
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• pp.536-540
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• 2007

The Ce-doped YAG(Yttrium Aluminum Garnet, $Y_3Al_5O_{12}$) phosphor powders were synthesized by combustion method. The luminescence, formation process and structure of phosphor powders were investigated by means of XRD, SEM and PL. The XRD patterns show that YAG Phase can form through sintering at $1000^{\circ}C$ for 2 h. This temperature is much lower than that required to synthesize YAG phase via the conventional solid state reaction method. There were no intermediate Phases such as YAP(Yttrium Aluminum Perovskite, $YAlO_3$) and YAM(Yttrium Aluminum Monoclinic, $Y_4Al_2sO_9$) observed in the sintering process. The powders absorbed excitation energy in the range $410{\sim}510\;nm$. Also, the crystalline YAG:Ce showed broad emission peaks in the range $480{\sim}600\;nm$ and had maximum intensity at 528 nm.

• The Korean Journal of Ceramics
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• v.1 no.1
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• pp.35-39
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• 1995

Yttrium aluminum garnet(YAG) powders were synthesized by spray-drying of the hydroxides coprecipitated from a mixture of aqueous solutions of $Al(NO_3)_3.9H_2O \;and\; Y(NO_3)_3.6H_2O$ Phase formation in the powders during heat treatments and their sintering charactristics were investigated. In the powder obtained by washing the hydroxides before spray-drying, a metastable yttrium aluminum hexagonal (YAH) phase was first crystallized and then transformed into YAG as temperature was increased. The formation of YAH was attributed to a deviation in compositions of the particles from the starting composition of YAG. However, the powder prepared without washing step contained a stable yttrium aluminum monoclinic(YAM) phase in addition to YAG due to a large deviation from the starting composition. A powder compact of a single phase YAG was pressureless-sintered for 4 hrs at $1700^{\circ}C$ and the density was 93% of the theoretical density.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.489-490
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• 2006

The Ce-doped YAG(Yttrium Aluminum Garnet, $Y_3Al_5O_{12}$) phosphor powders were synthesized by Sol-gel method. The luminescence, formation process and structure of phosphor powders were investigated by means of XRD, SEM and PL. The XRD patterns show that YAG phase can form through sintering at $1000^{\circ}C$ for 2h. This temperature is much lower than that required to synthesize YAG phase via the conventional solid state reaction method. There were no intermediate phases such as YAP(Yttrium Aluminum Perovskite, $YAlO_3$) and YAM(Yttrium Aluminum Monoclinic, $Y_4Al_2O_9$) observed in the sintering process. The powders absorbed excitation energy in the range 410~510nm. Also, the crystalline YAG:Ce showed broad emission peaks in the range 480~600nm and had maximum intensity at 528nm.

• Medical Lasers
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• v.10 no.2
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• pp.120-122
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• 2021

Partial unilateral lentiginosis (PUL) is an unusual pigmentary disorder characterized by numerous lentigines on the skin, with onset usually during early childhood. It is characterized by unilateral segmental distribution with sharp margins in one or more dermatomes. Conventional laser treatments result in several adverse effects, such as mottled pigmentary changes (hyper or hypopigmentation), especially in people of Asian descent. A 57-year-old man with PUL on the neck was treated with a high-fluence 1,064-nm Q-switched (QS) neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser. After 20 treatment sessions, the lesions markedly improved without adverse effects or recurrence. We suggest that high-fluence 1,064-nm QS Nd:YAG laser treatment is an effective and safe modality for PUL.

• Medical Lasers
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• v.10 no.2
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• pp.90-95
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• 2021

Background and Objectives Surgery for harvesting costal cartilage is often required for revision septorhinoplasty due to a lack of septal cartilage in patients with a severely contracted nose, and postoperative scarring on the anterolateral rib cage commonly requires additional treatment. This study aimed to evaluate the therapeutic efficacy and safety of combined polydeoxyribonucleotide (PDRN) and microlens array (MLA)-type nanosecond-domain neodymium (Nd):yttrium-aluminum-garnet (YAG) laser treatment for postoperative scars after costal cartilage harvest surgery. Materials and Methods Nine Korean patients with scars after costal cartilage harvest surgery treated with PDRN injections and MLA-type Nd:YAG laser treatments were retrospectively reviewed. Results Most of the scar lesions exhibited clinical improvement at 2 weeks after PDRN and MLA-type nanosecond-domain laser treatments, and the lesions further improved after adding more treatment sessions. The median Vancouver Scar Scale (VSS) score decreased from 6 (interquartile range [IQR]: 6-7) before combined intralesional PDRN injection and MLA-type, nanosecond-domain Nd:YAG laser treatments to 3 (IQR: 2-4) thereafter. Patient satisfaction after the combination treatments was rated as satisfactory. None of our patients reported major adverse events. Conclusion This case series study demonstrated that combined PDRN and MLA-type, nanosecond-domain Nd:YAG laser treatments are effective and safe for treating scars from costal cartilage harvest surgery.

• Korean Journal of Materials Research
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• v.21 no.2
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• pp.106-110
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• 2011

A high thermal conductive AlN composite coating is attractive in thermal management applications. In this study, AlN-YAG composite coatings were manufactured by atmospheric plasma spraying from two different powders: spray-dried and plasma-treated. The mixture of both AlN and YAG was first mechanically alloyed and then spray-dried to obtain an agglomerated powder. The spray-dried powder was primarily spherical in shape and composed of an agglomerate of primary particles. The decomposition of AlN was pronounced at elevated temperatures due to the porous nature of the spray-dried powder, and was completely eliminated in nitrogen environment. A highly spherical, dense AlN-YAG composite powder was synthesized by plasma alloying and spheroidization (PAS) in an inert gas environment. The AlN-YAG coatings consisted of irregular-shaped, crystalline AlN particles embedded in amorphous YAG phase, indicating solid deposition of AlN and liquid deposition of YAG. The PAS-processed powder produced a lower-porosity and higher-hardness AlN-YAG coating due to a greater degree of melting in the plasma jet, compared to that of the spray-dried powder. The amorphization of the YAG matrix was evidence of melting degree of feedstock powder in flight because a fully molten YAG droplet formed an amorphous phase during splat quenching.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.2917-2921
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• 2014

Cerium-activated yttrium aluminate ($Y_3Al_5O_{12}:Ce^{3+}$) exhibiting a garnet structure has been widely utilized in the production of light emitting diodes (LEDs) as a yellow emitting phosphor. The commercialized yttrium aluminum garnet (YAG) phosphor is typically synthesized by a solid-state reaction, which produces irregular shape particles with a size of several tens of micrometers by using the top-down method. To control the shape and size of particles, which had been the primary disadvantage of top-down synthetic methods, we synthesized YAG:Ce nanoparticles with a diameter of 500 nm using a coprecipitation method under the atmospheric pressure without the use of template or special equipment. The precursor particles were formed by refluxing an aqueous solution of the nitrate salts of Y, Al, and Ce, urea, and polyvinylpyrrolidone (55 K) at $100^{\circ}C$ for 12 h. YAG:Ce nanoparticles were formed by the calcination of precursor particles at $1100^{\circ}C$ for 10 h under atmospheric conditions. The phase identification, microstructure, and photoluminescent properties of the products were evaluated by X-ray powder diffraction, scanning electron microscopy, absorption spectrum and photoluminescence analyses.

• Medical Lasers
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• v.8 no.1
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• pp.24-27
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• 2019

Seborrheic keratoses (SKs) have been treated with non-ablative longpulsed (LP) lasers, including LP 532-nm neodymium (Nd): yttrium aluminum garnet (YAG), LP 695-nm ruby, LP 755-nm alexandrite (Alex), and LP 1,064-nm Nd:YAG lasers, with a pulse durations of 1-300 msec. Dual-wavelength LP 755-nm Alex/1,064-nm Nd:YAG laser systems have been used to remove hair follicles and treat various vascular and pigmented disorders by sequentially delivering two pulses of different wavelengths with interpulse intervals in the millisecond range. This paper reports the case of a female patient with multiple, discrete, light brown SKs on the dorsum of both hands that were treated effectively with one session of dual-wavelength LP 1,064-nm Nd:YAG/755-nm Alex laser treatment. The treatment settings for the LP Nd:YAG laser were comprised of a wavelength of 1,064 nm, fluence of 50 J/cm², pulse duration of 5 msec, and beam size of 3 mm. The settings for the LP Alex laser were comprised of a wavelength of 755 nm, fluence of 50 J/cm², pulse duration of 5 msec, and beam size of 3 mm. A hybrid mode was used to automatically deliver LP Nd:YAG and LP Alex laser pulses in succession at interpulse intervals of 20 msec. Six weeks after treatment, the patient exhibited remarkable improvement of the light brown seborrheic keratoses and was satisfied with the results.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.324-331
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• 1998

After the addition of yttrium aluminum garnet of 2, 5, 10 mol% as a sintering aid, $\alpha$-silicon carbides were prepared by a liquid-phase sintering at $1850^{\circ}C$, and the microstructural evolution was investigated during sintering as functions of liquid-phase amount and sintering time. The highest apparent density in each compositions was obtained in specimens sintered for 2 h, and the percentage of weight loss increased with sintering time. By increasing the amount of sintering aid (yttrium aluminum garnet), the rate of grain growth during sintering decreased, but the apparent density of sintered body increased. The phase transformation from 6H-SiC to 4H-SiC was partially observed in specimens sintered for a long time, and so, a few rod-like grains were observed.

• Journal of Powder Materials
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• v.13 no.4 s.57
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• pp.243-249
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• 2006

Yttrium aluminum garnet (YAG) powders were synthesized via mechanochemical solid reaction using $Y_2O_3$ with three types of aluminum compounds. $Y_2O_3$ reacted mechanochemically with all A1 compounds and formed YAM (yttrium aluminum monoclinic), YAG and YAP (yttrium aluminum perovskite) phases depending on the starting materials. The ground samples containing ${\gamma}-A1_2O_3$ showed the best reactivity, whereas the ground sample containing A100H, which had the largest surface area, exhibited pure YAG after calcination at $1200^{\circ}C$. The sample containing Al had the least reactivity, producing YAP along with YAG at $1200^{\circ}C$. The types and grinding characteristics of the starting materials and grinding time are believed to be important factors in the mechanochemical synthesis of YAG.