Review
Review
Review
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∫∑§«“¡<br />
«“√ “√«‘∑¬“»“ µ√å ¡¢. ªï∑’Ë 39 ©∫—∫∑’Ë 1 75<br />
√Ÿª∑’Ë 4 a) ‚æ≈“‰√‡´—π‡°‘¥‡Õß (spontaneous polarization) „π‚¥‡¡π¢Õß “√ª√–°Õ∫‡ø√å‚√Õ‘‡≈Á°∑√‘°<br />
b) ª√–®ÿ∑’˺‘«¢Õ߇°√π (surface charge) ´÷Ë߇°‘¥®“°º≈√«¡¢Õß‚æ≈“‰√‡´—π‡°‘¥‡ÕߢÕ߇°√π∑’ËÕ¬Ÿà<br />
µ‘¥°—π<br />
(¥—¥·ª≈ß®“°: Huybrechs, 1995)<br />
π—°«‘∑¬“»“ µ√åπ” PTCR- BaTiO 3<br />
‰ª„â<br />
∑”µ—«∑”§«“¡√âÕπ (heating element) ∑’˵—¥‰ø‡Õ߉¥â<br />
‚¥¬Õ—µ‚π¡—µ‘‰¡àµâÕß„â«ß®√‰øøÑ“ ‚¥¬Õ“»—¬À≈—°°“√<br />
∑’Ë«à“∑’ËÕÿ≥À¿Ÿ¡‘µË”°«à“Õÿ≥À¿Ÿ¡‘§Ÿ√’ µ—«∑”§«“¡√âÕπ<br />
¡’ ¿“槫“¡µâ“π∑“π‰øøÑ“„πµ—«‰¡à¡“° ®÷߬ա„Àâ<br />
‰øøÑ“«‘Ëߺà“πµ—«¡—π·≈â«„À⧫“¡√âÕπÕÕ°¡“‡À¡◊Õπ<br />
°—∫‰ âÀ≈Õ¥‰øøÑ“ µàÕ¡“‡¡◊ËÕµ—«¢Õß¡—π¡’Õÿ≥À¿Ÿ¡‘ Ÿß<br />
¢÷Èπ®π°√–∑—Ëß Ÿß°«à“Õÿ≥À¿Ÿ¡‘§Ÿ√’ PTCR- BaTiO 3<br />
®–¡’<br />
¿“槫“¡µâ“π∑“π‰øøÑ“ Ÿß¢÷ÈπÕ¬à“ß∑—π∑’À≈“¬æ—π‡∑à“<br />
∑”„Àâ‰øøÑ“«‘Ëߺà“πµ—«¡—π‰¡à‰¥â ¡—π®÷ßÀ¬ÿ¥„À⧫“¡<br />
√âÕπÕÿ≥À¿Ÿ¡‘®÷ߵ˔≈ß ·≈–®–„À⧫“¡√âÕπÕÕ°¡“Õ’°∑’<br />
‡¡◊ËÕµ—«¡—π¡’Õÿ≥À¿Ÿ¡‘µË”°«à“Õÿ≥À¿Ÿ¡‘§Ÿ√’<br />
º≈¢Õß°“√‡µ‘¡‰ÕÕÕπµ—«√—∫„π PTCR-BaTiO 3<br />
ºŸâº≈‘µ PTCR ®“° BaTiO 3<br />
∑’ˇµ‘¡ “√‡®◊Õµ—«<br />
„Àâ¡—°®–‡µ‘¡‰ÕÕÕπÀ√◊ÕÕ–µÕ¡¢Õß∏“µÿ·∑√π´‘—π<br />
≈߉ª„π à«πº ¡¥â«¬ ‡æ√“–®“°ß“π«‘®—¬æ∫«à“°“√<br />
‡µ‘¡Õ–µÕ¡¢Õß∏“µÿ·∑√π´‘—π∫“ßµ—« ‡àπ Fe, Cr ·≈–<br />
Mn ‡¢â“‰ª„π BaTiO 3<br />
∑’ˇ®◊ե⫬‰ÕÕÕπµ—«„À⮖૬<br />
‡æ‘Ë¡ ¡∫—µ‘ PTCR ‰¥â¥—ß· ¥ß„π√Ÿª∑’Ë 5 ‡π◊ËÕß®“°<br />
‰ÕÕÕπ¢Õß∏“µÿ·∑√π´‘—π∑’ˇµ‘¡≈߉ªπ—Èπ¡’‡«‡≈π´’<br />
µË”°«à“‰ÕÕÕπ¢Õß BaTiO 3<br />
®÷ß∂◊Õ«à“°“√‡µ‘¡‰ÕÕÕπ¢Õß<br />
∏“µÿ∑√“π´‘—π‡ªìπ°“√‡®◊Õ BaTiO 3<br />
¥â«¬‰ÕÕÕπµ—«√—∫<br />
Ueoka (1974) Õ∏‘∫“¬°“√‡µ‘¡ Mn 2+ ≈߉ª„π BaTiO 3<br />
«à“∑’ËÕÿ≥À¿Ÿ¡‘ ŸßÊ °“√‡µ‘¡ Mn 2+ ®–∑”„Àâ BaTiO 3<br />
ª√—∫<br />
ª√–®ÿ„Àâ ¡¥ÿ≈‚¥¬°“√‡°‘¥àÕß«à“ߢÕßÕÕ°´‘‡®π<br />
(oxygen vacancies; ) Õ¬à“߉√°Áµ“¡ ®–¡’®”π«π<br />
≈¥≈߇¡◊ËÕ≈¥Õÿ≥À¿Ÿ¡‘≈ß¡“∑’ËÕÿ≥À¿Ÿ¡‘ÀâÕß„π∫√√¬“°“»<br />
ª°µ‘ ∑”„Àâ Mn 2+ ´÷Ëß∂Ÿ°‡µ‘¡‡¢â“‰ª·∑π∑’Ë Ti 4+ „π<br />
BaTiO 3<br />
‡ª≈’Ë¬π‡«‡≈π´’‡ªìπ Mn 3+ À√◊Õ Mn 4+ ‡æ◊ËÕ√—°…“<br />
¡¥ÿ≈¢Õߪ√–®ÿ¢Õß√–∫∫ Mn ‰ÕÕÕπ∑’Ë¡’‡«‡≈π´’ ŸßÊ<br />
‡À≈à“π’È®–∑”Àπâ“∑’˧լ®—∫Õ‘‡≈Á°µ√Õπ∑”„Àâ°”·æß»—°¬å<br />
µ“¡·∫∫®”≈ÕߢÕß Heywang Ÿß¢÷Èπ ¥—ßπ—Èπ°“√‡µ‘¡<br />
Mn 2+ ‡¢â“‰ª®÷ß∑”„Àâ BaTiO 3<br />
∑’ˇ®◊ե⫬µ—«„Àâ· ¥ß<br />
¡∫—µ‘ PTCR ¡“°¬‘Ëߢ÷Èπ Õ“®®–‡¢’¬π ¡°“√‡§¡’¢Õß<br />
°“√‡°‘¥µ”À𑵓¡§”Õ∏‘∫“¬¢Õß Ueoka ‰¥â¥—ßπ’È