A-site Vacancy가 0.97Bi 0.5+x (Na 0.78 K 0.22) 0.5-3x TiO 3-0.03LaFeO 3 무연압전 세라믹스의 압전특성에 미치는 영향 박정수 • 이규탁 • 조정호 • 정영훈 • 백종후 • 윤지선 † 한국세라믹기술원 전자소재융합본부 (2014년 9월 17일 접수 ; 2014년 11월 7일 수정 ; 2014년 11월 11일 채택) ABSTRACT 0.97Bi 0.5+x (Na 0.78 K 0.22) 0.5-3x TiO 3-0.03LaFeO 3 lead-free piezoelectric ceramics were fabricated by a solid state reaction method. LaFeO 3 additives were added to Bi 0.5 (Na 0.78 K 0.22) 0.5 TiO 3 for volatile compensation of bismuth and sodium ions in the sintering process. To create A-site vacancies, the mole ratio and charge valence of A-site ions (Bi 3+ , Na + and K +) were controlled. The improved piezoelectric properties were observed by addition of LaFeO 3 and control of A-site vacancies. In particular, a d 33 *(S max /E max) value of 614pm/V and an electric field induced strain of 0.33% was observed in 0.97Bi 0.505 (Na 0.78 K 0.22) 0.485 TiO 3-0.03LaFeO 3 ceramic.

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The purpose of this study was to examine the effect of phytoncide Aroma inhalation and exercise combination therapy on the college life stress, mood state and sleep pattern of the university students. Participants were 72 college students of four groups of Phytoncide Aroma Inhalation group(n=18), Exercise group(n=17), Phytoncide Aroma Inhalation and exercise combination therapy group(n=17), control group(n=20). Research subjects pre-test(0week), mid-test(6week), post-test(12week) measurement was made equally on college life stress, mood state and sleep pattern. As a result, mood status, college life satisfaction and sleep scores were improved in all groups except the control group. Especially, phytoncide inhalation and exercise combination therapy group showed the greatest change in scores.

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