Review

«.«‘∑¬. ¡¢. 39(1) 71-79 (2554) KKU Sci. J.39(1) 71-79 (2011)
µ—«∑”§«“¡√âÕπ PTCR-BaTiO 3
PTCR-BaTiO 3
Heating Element
ÿ∏√√¡ »√’À≈à¡ —° 1
·∫∫®”≈Õß°“√π”‰øøÑ“¢Õß BaTiO 3
∑’ˇ®◊ե⫬
‰ÕÕÕπµ—«„Àâ
Barium titanate (BaTiO 3
) ‡ªìπ«— ¥ÿÕ‘‡≈Á°-
∑√Õπ‘° å∑’Ë„â°—π¡“°∑’Ë ÿ¥π‘¥Àπ÷Ëß ¡’°“√π” BaTiO 3
∑’Ë∂Ÿ°‡®◊Õ (doped BaTiO 3
) ‰ª„â„πß“πµà“ßÊ ¡“° ‡àπ
∑”µ—«‡ªìπª√–®ÿ∑’Ë¡’À≈“¬—Èπ (multilayer capacitors;
MLC), ·∑√π 契«‡´Õ√å (transducer) Àπ૬§«“¡®”
‡ø√å‚√Õ‘‡≈Á°∑√‘°·∫∫øî≈å¡∫“ß (ferroelectric thin film
memories) ·≈–µ—«∑”§«“¡√âÕπ (heating element) À√◊Õ
µ—«√—∫√Ÿâ (sensor) œ≈œ BaTiO 3
∑’Ë∂Ÿ°‡®◊ե⫬ՖµÕ¡
À√◊Õ‰ÕÕÕπ∑’ˇªìπµ—«„Àâ (donor) ‡ªìπ‡´√“¡‘°∑’Ë¡’ ¡∫—µ‘
PTCR (positive temperature coefficient resistance)
´÷Ëß¡’ ¿“æµâ“π∑“π‰øøÑ“‡æ‘Ë¡¢÷ÈπÕ¬à“ß√«¥‡√Á«„πà«ß
Õÿ≥À¿Ÿ¡‘·§∫Ê „°≈âÊ Õÿ≥À¿Ÿ¡‘§Ÿ√’ (Curie point; T C
)
(Capurso, 1998) ¥—ß· ¥ß„π√Ÿª∑’Ë 1 ª√“°Ø°“√≥å PTCR
∂Ÿ°§âπæ∫·≈–∫—π∑÷°‰«â§√—Èß·√°„πªï 1955 (Haayman,
1955) „π‡«≈“µàÕ¡“π—°«‘∑¬“»“ µ√åÀ≈“¬∑à“π √â“ß·∫∫
®”≈Õß (model) À≈“¬Ê ·∫∫¡“Õ∏‘∫“¬ª√“°Ø°“√≥å
PTCR „π BaTiO 3
∑’ˇ®◊ե⫬µ—«‰ÕÕÕπ„Àâ (donor doped
BaTiO 3
)
√Ÿª∑’Ë 1 ¿“æµâ“π∑“π‰øøÑ“ (electrical resistivity; ρ) µàÕÕÿ≥À¿Ÿ¡‘ ¢Õ߇´√“¡‘°∑’Ë· ¥ß ¡∫—µ‘ PTCR ¢π“¥
§«“¡‡ªìπ PTCR (PTCR magnitude À√◊Õ PTCR jump) À“‰¥â®“°Õ—µ√“ à«π√–À«à“ß ¿“æµâ“π∑“π
‰øøÑ“ Ÿß ÿ¥ (maximum resistivity; ρ max
) µàÕ ¿“æµâ“π∑“π‰øøÑ“µË” ÿ¥ (minimum resistivity; ρ min
)
1
“¢“«‘“«‘»«°√√¡‡´√“¡‘° ”π—°«‘“«‘»«°√√¡»“ µ√å ¡À“«‘∑¬“≈—¬‡∑§‚π‚≈¬’ ÿ√π“√’ ®.π§√√“ ’¡“ 30000
E-mail: sutamsri@sut.ac.th