Development of Lead-Free PTC Thermistor Materials

Shiosaki, Tadashi; Takeda, Hiroaki; Goto, Ryuhei; Kinoshita, Tsukuru; Shimada, Takeshi; Katsuyama, Yoshiaki

doi:10.1109/isaf.2006.4387858

Cited by 4 publications

(4 citation statements)

References 5 publications

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“…It is worth noting that for each composition we found a region with a PTC for the resistivity, ρ = 1/σ, that might correspond to grain boundary conduction, as reported by other authors in compounds based on the BaTiO 3 semiconductor ceramics . Lead-free PTC resistors are used in devices as temperature sensors and controllers, heaters, overheating or electric shock protection, and smart control devices . We have observed a shift in the region of a PTC upon going to lower temperature ranges with increasing La content (300–440 °C for Bi 0.5 La 0.5 Fe 0.5 Cr 0.5 O 3 , 28–380 °C for Bi 0.4 La 0.6 Fe 0.5 Cr 0.5 O 3 , and 260–340 °C for Bi 0.3 La 0.7 Fe 0.5 Cr 0.5 O 3 ).…”

Section: Resultssupporting

confidence: 80%

“…21 Lead-free PTC resistors are used in devices as temperature sensors and controllers, heaters, overheating or electric shock protection, and smart control devices. 22 We have observed a shift in the region of a PTC upon going to lower temperature ranges with increasing La content (300À440 °C for Bi 0.5 La 0.5 Fe 0.5 Cr 0.5 O 3 , 28À380 °C for Bi 0.4-La 0.6 Fe 0.5 Cr 0.5 O 3 , and 260À340 °C for Bi 0.3 La 0.7 Fe 0.5 Cr 0.5 O 3 ).…”

Section: ' Results and Discussionmentioning

confidence: 99%

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New Fe³⁺/ Cr³⁺ Perovskites with Anomalous Transport Properties: The Solid Solution La_xBi_1–xFe_0.5Cr_0.5O₃ (0.4 ≤ x ≤ 1)

Villafuerte‐Castrejon

García-Guaderrama

Fuentes

et al. 2011

Inorg. Chem.

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In this work, the sol-gel synthesis, structural characterization, and transport properties of a new solid solution of the general formula La(x)Bi(1-x)Fe(0.5)Cr(0.5)O(3) (0.4 ≤ x ≤ 1) are presented. The solubility limit x has been determined and variation of the lattice parameters measured through profile fitting. The cell parameters, space group, and atomic positions, as obtained by the Rietveld refinement of X-ray diffraction data, are reported. This analysis and electron diffraction studies as well do not reveal any evidence of Fe/Cr ordering. Regarding the transport properties, magnetic and electric characterizations are described. The electrical response with the temperature and frequency has been studied, and a "positive temperature coefficient" for the resistivity has been found for temperatures between 270 and 400 °C. The magnetic behavior is striking because, for all materials studied, zero-field-cooling curves appear above field-cooling ones, an anomalous feature that is interpreted as being due to complex ferromagnetic/antiferromagnetic interactions in the B perovskite sublattice.

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Section: Resultssupporting

confidence: 80%

Section: ' Results and Discussionmentioning

confidence: 99%

New Fe³⁺/ Cr³⁺ Perovskites with Anomalous Transport Properties: The Solid Solution La_xBi_1–xFe_0.5Cr_0.5O₃ (0.4 ≤ x ≤ 1)

Villafuerte‐Castrejon

García-Guaderrama

Fuentes

et al. 2011

Inorg. Chem.

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“…We demonstrated that in BT–BNT solid solutions the transition temperature increased with BNT additions, reaching ~177°C for 30 mol% BNT, but that the optimum PTCR effect (in excess of four orders of magnitude increase in resistivity at T c ) was achieved for the addition of 8.8 mol% BNT. Sintering in an atmosphere with a low O 2 partial pressure, of the order of ppm, was important for achieving low resistivity values at room temperature . Subsequently Takeda et al .…”

Section: Introductionmentioning

confidence: 99%

(Ba_1+xTiO₃)–(Bi_0.5Na_0.5TiO₃) Lead‐Free, Positive Temperature Coefficient of Resistivity Ceramics: PTC Behavior and Atomic Level Microstructures

et al. 2012

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Positive temperature coefficient of resistivity (PTCR) ceramics of 0.912(Ba 1+x TiO 3 )-0.088(Bi 0.5 Na 0.5 TiO 3 ) (BT-BNT) (x = À0.03 to 0.03) were prepared using the mixed oxide route and sintered at 1340°C for 4 h. Products were predominantly single phase with a tetragonal structure and grains in 2-6 lm size containing 90°ferroelectric domains. Samples with Ti/Ba > 1 contained second-phase Ba 6 Ti 17 O 40 . HRTEM and aberrationcorrected Z-contrast high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) suggested that the dopants, Bi and Na, occupy the Ba site of the perovskite lattice, and revealed the presence of dissociated dislocations in x = À0.03 and x = 0.00 materials. The interval between two partial dislocations was 1.9-3.4 nm, yielding stacking fault energies of 363-649 mJ/m 2 . The PTCR behavior of the ceramics increased with Ti/Ba content, reaching a maximum of six decades change in resistivity for x = À0.03. The anomalous increase in resistivity depends critically on stoichiometry, increasing with the Ti/Ba ratio; this in turn is directly correlated with an increase in the amount of secondphase Ba 6 Ti 17 O 40 , an increase in the stacking fault energy, and an increase in the tilt angle of the grain boundaries.

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“…The complex compounds of (Bi 0.5 Na 0.5 )TiO 3 (BNT, Tc =320ºC) [5], (Bi 0.5 K 0.5 )TiO 3 (BKT, Tc =380ºC) [5], NaNbO 3 (T c =643ºC) [6], BiFeO 3 (Tc =850ºC) [7] are potential candidates to fabricate lead-free PTCR materials with Tc > 120ºC. Tadashi Shiosaki [8] reported that BT-BNT solid solution demonstrated low resistivity values on the order of 10Ωcm at room temperature and an abrupt resistivity change near Tc. In 2007, Ping-Hua Xiang have successfully found a excellent PTCR effect in xBaTiO 3 -(1-x)(Bi 1/2 Na 1/2 )TiO 3 (x=10,20mol%) based materials, which exhibits resistivity jumps of about 10 3 -10 5 starting at about 190-210ºC [9].…”

Section: Introductionmentioning

confidence: 99%

Study on the Effects of (Bi1/2Na1/2)TiO3 Content on the Curie Temperature of (Bi1/2Na1/2)TiO3-BaTiO3 PTCR Ceramics

Yang

Zhu

et al. 2011

MSF

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Perovskite-structured (Bi1/2Na1/2)TiO3 (BNT) ferroelectric with Curie temperature about 320°C is considered to be a good candidate of high temperature lead-free materials with a positive temperature coefficient of resistance (PTCR). In this study, lead-free PTCR ceramics with compositions of (1-x)BaTiO3-x(Bi1/2Na1/2)TiO3 (BT-BNT x=0.5-55mol%) were successfully prepared without any additional donor or acceptor dopants. The effects of BNT content on the Curie temperature Tc and the PTC effect of the ceramic materials were investigated. The X-ray diffraction data indicated that BT phase and BNT phase formed a solid solution during sintering even though the x value was up to 55mol%. The Curie temperature Tc of the samples increased from ~130°C to ~216°C with the increase of the BNT amount (x value) from 0.5mol% to 40mol%. However, it decreased when excess BNT was added (x value increased from 40mol% up to 55mol%), which was resulted from the volatile effects of Bi3+ and Na+ ions during sintering. The sample of 0.6BaTiO3- 0.4(Bi1/2Na1/2)TiO3 with Tc =216°C, room-temperature resistivity 104 Ω·cm and Rmax/Rmin= 102.7 was obtained. There is a relationship between the Curie temperature and the cell volume of the perovskite structured lattice.

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Development of Lead-Free PTC Thermistor Materials

Cited by 4 publications

References 5 publications

New Fe³⁺/ Cr³⁺ Perovskites with Anomalous Transport Properties: The Solid Solution La_xBi_1–xFe_0.5Cr_0.5O₃ (0.4 ≤ x ≤ 1)

New Fe³⁺/ Cr³⁺ Perovskites with Anomalous Transport Properties: The Solid Solution La_xBi_1–xFe_0.5Cr_0.5O₃ (0.4 ≤ x ≤ 1)

(Ba_1+xTiO₃)–(Bi_0.5Na_0.5TiO₃) Lead‐Free, Positive Temperature Coefficient of Resistivity Ceramics: PTC Behavior and Atomic Level Microstructures

Study on the Effects of (Bi<sub>1/2</sub>Na<sub>1/2</sub>)TiO<sub>3</sub> Content on the Curie Temperature of (Bi<sub>1/2</sub>Na<sub>1/2</sub>)TiO<sub>3</sub>-BaTiO<sub>3</sub> PTCR Ceramics

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Development of Lead-Free PTC Thermistor Materials

Cited by 4 publications

References 5 publications

New Fe3+/ Cr3+ Perovskites with Anomalous Transport Properties: The Solid Solution LaxBi1–xFe0.5Cr0.5O3 (0.4 ≤ x ≤ 1)

New Fe3+/ Cr3+ Perovskites with Anomalous Transport Properties: The Solid Solution LaxBi1–xFe0.5Cr0.5O3 (0.4 ≤ x ≤ 1)

(Ba1+xTiO3)–(Bi0.5Na0.5TiO3) Lead‐Free, Positive Temperature Coefficient of Resistivity Ceramics: PTC Behavior and Atomic Level Microstructures

Study on the Effects of (Bi<sub>1/2</sub>Na<sub>1/2</sub>)TiO<sub>3</sub> Content on the Curie Temperature of (Bi<sub>1/2</sub>Na<sub>1/2</sub>)TiO<sub>3</sub>-BaTiO<sub>3</sub> PTCR Ceramics

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New Fe³⁺/ Cr³⁺ Perovskites with Anomalous Transport Properties: The Solid Solution La_xBi_1–xFe_0.5Cr_0.5O₃ (0.4 ≤ x ≤ 1)

New Fe³⁺/ Cr³⁺ Perovskites with Anomalous Transport Properties: The Solid Solution La_xBi_1–xFe_0.5Cr_0.5O₃ (0.4 ≤ x ≤ 1)

(Ba_1+xTiO₃)–(Bi_0.5Na_0.5TiO₃) Lead‐Free, Positive Temperature Coefficient of Resistivity Ceramics: PTC Behavior and Atomic Level Microstructures