Fabrication of Lead-Free and High Tc Positive Temperature Coefficient of Resistivity Ceramics Sintered in Air

2011 ◽  
Vol 415-417 ◽  
pp. 1005-1008
Author(s):  
Jun Zhao ◽  
Hai Bo Yang ◽  
Shu Ping Gong ◽  
Dong Xiang Zhou
Keyword(s):  
Temperature Coefficient ◽  
Solid State Reaction Method ◽  
Positive Temperature Coefficient ◽  
Lead Free ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Conventional Solid State Reaction ◽  
High Tc ◽  
C Value ◽  
Temperature Coefficient Of Resistivity

As a lead-free positive temperature coefficient of resistivity (PTCR) material, [Ba0.95-x (K0.5Bi0.5)0.05Cax]1-yNbyO3 system was prepared by the conventional solid-state reaction method. All samples sintered in air at 1300°C possess PTC characteristics as well as semi-conductivity characteristics, especially they show high Tc(130°C~160°C) value and the jump of the resistivity (maximum resistivity ρmax / minimum resistivity ρmin ) is four orders of magnitude. Samples with the composition of 0.3mol% Nb5+ have low room-temperature resistivity (ρ25°C) of ~103Ω.cm.

Electrical Properties of Nb-Doped and Nb-Mn-Codoped BaTiO3-(Bi0.5Na0.5)TiO3 Lead-Free PTCR Ceramics

2010 ◽  
Vol 67 ◽  
pp. 134-142
Author(s):  
Guo Rong Li ◽  
Sen Lin Leng ◽  
Liao Ying Zheng ◽  
Jiang Tao Zeng ◽  
Zhi Jun Xu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Solid State Reaction Method ◽  
Positive Temperature Coefficient ◽  
Lead Free ◽  
High Resistivity ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Conventional Solid State Reaction ◽  
Xrd Patterns ◽  
Temperature Resistivity

Nb-doped and Nb-Mn-codoped (1-xmol%)BaTiO3-xmol%(Bi0.5Na0.5)TiO3 (BBNTx) lead-free positive temperature coefficient of resistivity (PTCR) ceramics were prepared by the conventional solid state reaction method. The XRD patterns indicated that all BBNTx samples formed a single perovskite structure with tetragonal phase. 0.25 mol% Nb doped BBNT1 ceramic, sintered at 1330°C for 1h in air, had low room-temperature resistivity (ρ25) of 80 Ω•cm and a high resistivity jump (maximum resistivity [ρmax]/minimum resistivity [ρmin]) of 4.2 orders of magnitude with Tc about 152°C. The Nb-doped BBNTx (10≤x≤60) ceramics also showed distinct PTC effect with Tc between 185 and 232°C by sintering in N2, which was shut off when samples were cooled to a low temperature. In addition, The Nb-Mn-codoped BBNT1 ceramics exhibited higher resistivity jump than the single Nb-doped ones, with increasing the room-temperature resistivity.

Positive temperature coefficient of resistivity effect in Pb-doped KnbO3

2002 ◽  
Vol 17 (12) ◽  
pp. 2989-2992 ◽  
Author(s):  
Irena Pribošič ◽  
Darko Makovec ◽  
Miha Drofenik
Keyword(s):  
Phase Transition ◽  
Temperature Coefficient ◽  
Ferroelectric Material ◽  
Positive Temperature Coefficient ◽  
Cubic Phase ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Ptcr Effect ◽  
Temperature Coefficient Of Resistivity ◽  
Temperature Resistivity

KnbO3 is a ferroelectric material with a Curie temperature (TC) at 415°C, thus giving it the potential to be a material for high-temperature positive temperature coefficient of resistivity (PTCR) applications. In this study, we investigated the PTCR effect in donor-doped KnbO3 ceramics containing 0, 0.1, 0.2, and 0.3 mol% PbO. The donor-doped KnbO3 ceramics exhibited a PTCR anomaly with a relatively low room-temperature resistivity. The temperature of the tetragonal-to-cubic phase transition (TC) of the KnbO3 decreased with the amount of added PbO, while the orthorhombic-to-tetragonal phase transition (TOT) remained unchanged.

Electrical and thermal properties of a (Ba1-x-ySrxCay)TiO3-based PTC thermistor for preheating light oil

2018 ◽  
Vol 11 (05) ◽  
pp. 1850076 ◽  
Author(s):  
Joonsoo Kim
Keyword(s):  
Thermal Properties ◽  
Electrical Properties ◽  
Solid State Reaction Method ◽  
Positive Temperature Coefficient ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Conventional Solid State Reaction ◽  
Heater Element ◽  
Light Oil ◽  
Cartridge Heater

The electrical properties of a (Ba[Formula: see text]SrxCay)TiO3-based positive temperature coefficient (PTC) thermistor were determined by measuring resistivity with increasing temperature, and its thermal properties were measured with a cartridge heater made of a (Ba[Formula: see text]Sr[Formula: see text]Ca[Formula: see text])TiO3-based PTC thermistor. The (Ba[Formula: see text]SrxCay)TiO3-based PTC thermistor were fabricated by a conventional solid-state reaction method with Sb2O3, BaTiO3, SrTiO3, SiO2, and CaTiO3. Their electrical properties were determined by room temperature resistivity ([Formula: see text]C), minimum resistivity ([Formula: see text]), maximum resistivity ([Formula: see text]), resistivity jump rate (log [Formula: see text]/[Formula: see text]), Curie temperature ([Formula: see text]), and withstanding voltage. The effect of the microstructure on the electrical properties was investigated to improve the withstand voltage. The cartridge heater was fabricated with the (Ba[Formula: see text]Sr[Formula: see text]Ca[Formula: see text])TiO3-based PTC thermistor and its thermal properties were determined by the temperature of light oil in a 100 cc beaker. The temperature of light oil was maintained at 60[Formula: see text]C without fluctuations in temperature after reaching 60[Formula: see text]C at 220[Formula: see text]V, and thus (Ba[Formula: see text]SrxCay)TiO3-based PTC thermistor was able to operate as a self-regulating heater element for preheating light oil.

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