• Title/Summary/Keyword: Mophology control

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Effects of two-step deposition on the property of AlN films and the device characteristic of AlN-based FBARs (2단계 증착 방법이 AlN 박막의 물성 및 체적 탄성파 소자의 특성에 미치는 영향)

  • Cho, Dong-Hyun;Jung, Jun-Phil;Lee, Jin-Bock;Park, Jin-Seok
    • Proceedings of the KIEE Conference
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    • 2003.07c
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    • pp.1577-1579
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    • 2003
  • AlN thin films are prepared on Si (111) substrate by RF magnetron sputtering. Two-step deposition method is proposed to obtain AlN thin films with high c-axis (002)-TC value and low surface roughnesses. For all the deposited AlN films, the c-axis (002)-orientation, surface mophology, and roughness are characterized in terms of deposition conditions FEAR devices with Al/AlN/Mo/Si(111) configuration are also fabricated. From the frequency response characteristics, the return loss and electromechanical coupling contant($k_t{^2}$) are estimated.

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CLEANLINESS AND WALL MOPHOLOGY OF ULTRASONIC ROOT-END RETROGRADE CAVITY (초음파로 형성된 치근단 역충전와동의 정화도 및 와벽형태)

  • Kim, Sung-Kyo;Lee, Jae-Whan;Baek, Seung-Moo
    • Restorative Dentistry and Endodontics
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    • v.22 no.2
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    • pp.536-545
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    • 1997
  • The purposes of this study were to evaluate the degree of cavity cleanliness and to observe cavity wall morphology when root-end retrograde cavity preparation was done with ultrasonics. Root resections were done on 20 extracted human maxillary central incisors after canal filling with gutta-percha, and retrocavities were prepared using a slow-speed round bur as a control, and stainless steel ultrasonic tips of power settings of 2 and 6 ($Miniendo^{TM}$, EIE, SA, USA) as experimentals. The degree of the remaining cavity debris and smear layer, and wall morphology were evaluated under the scanning electron microscope. The results were as follows : Cavity prepared with ultrasonics of either power setting showed significantly less smear layer than did slow-speed preparations (p<0.01). However, there was no significant difference in canal debris (p<0.05). Cavity prepared with ultrasonics showed hatcheted appearance of wall, while slow-speed preparation showed relatively plain one.

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Synthesis of Cubic and Rod Shapes CaCO3 by Hydrothermal Method (수열합성법을 이용한 큐빅과 로드형의 탄산칼슘 합성)

  • Kang, Kuk-Hyoun;Jeon, Sang-Chul;Hyun, Mi-Ho;Lee, Dong-Kyu
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.6
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    • pp.255-261
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    • 2016
  • $CaCO_3$ was applied in various industries including rubber, plastics, paint, paper, food additives, and acid neutralizer, etc., owing to its excellent physical and chemical characteristics as well as various appearances of crystals and many reserves. In particular, research on controlling the structure and shape of $CaCO_3$ has attracted considerable attention recently, because the whiteness and physical characteristics of $CaCO_3$ depend on the size and shapes of the particles. In this study, $CaCO_3$ was synthesized using $CaCl_2$ and $(NH4)_2CO_3$, which has multi-shapes and structures, using a self-assembly method with a hydrothermal method. The structure and morphology of the $CaCO_3$ could be controlled by adjusting the pH and precursor concentration. In particular, the pH adjustment appeared to be a critical factor for the morphology and crystal form. In addition, the calcite and cubic shape were obtained at pH 7, while the mixed calcite, aragonite structure, and rod shapes appeared at pH 7 and over. Through an analysis of the particle formation process, the formation of the calcium carbonate particles was confirmed. The physicochemical properties of the synthesized $CaCO_3$ were analyzed by SEM, XRD, EDS, FTIR, and TG/DTA.