BaTiO_3-based PTC ceramics have unique resistance-temperature characteristics. In a very narrow temperature range near Curie temperature TC, its resistance can rapidly increase by several orders of magnitude. There are two characteristic temperatures in the resistance-temperature characteristics of typical BaTiO _ 3-based PTC ceramics, one is the minimum resistivity temperature T_(ρmin), and the other is the maximum resistivity temperature T_(ρmax). When the temperature is lower than T(ρmin), it shows NTC effect. When it is between T_(ρmin) and T_(ρmax), it shows PTC effect; When the temperature is higher than T_(ρmax), NTC effect will appear again. In the past, most of the research on barium titanate-based PTC ceramics focused on the origin of PTC effect and the regulation of positive temperature coefficient, but there were few reports on NTC effect. This paper is carried out under this background, aiming at exploring the origin of PTC effect by studying the NTC effect of BaTiO _ 3-based PTC ceramics, and trying to combine NTC and PTC effect, hoping to develop a new type of dual-function thermistor and realize the integration of sensing and control. Through a series of research, the following results are obtained in this paper: 1. Yttrium-doped barium titanate ceramics have NTC characteristics at both low and high temperatures. Nb doped BaTiO_3 ceramics have no NTC characteristics at low temperature, but have NTC characteristics at high temperature. 2. In the temperature range of -55℃~ 10℃ (orthogonal phase), 10℃~ T(ρmin) (tetragonal phase) and T(ρmax)~ 400℃ (cubic phase), the barrier height of yttrium-doped barium titanate ceramics is constant, but at the phase transition temperature. Orthogonal-tetragonal phase transition reduces the barrier height, while tetragonal-cubic phase transition increases the barrier height. 3.Pb partially replaces Y-doped Ba TiO_3 ceramics, which improves the low-temperature NTC characteristics and reduces the PTC characteristics. At 1280℃, the composition of the sample is (ba _ (0.8464) y _ (0.0036) Pb _ (0.15)) TiO _ 3+0.1wt% Al2O3+0.5 wt%. 4. The partial substitution of strontium for yttrium-doped barium titanate ceramics reduces the NTC characteristics at high temperature, and a small amount of strontium (

[Keywords]: PTC ceramics; NTC effect; Transmission mechanism; crystal boundary

[Literature type]: Master's thesis

[Source]: South China University of Technology 20 18

Download this article

refer to

Study on high performance barium strontium titanate PTC material

Preparation and Properties of Paper | Bulk, Thick Film and Thin Film NTC Thermistors

Study on barium titanate-based composite PTC materials

* * * Reference file

Characteristics of Periodic Mn(NO_3)_2 Doped BaTiO_3 Semiconductor Materials

Two references

Paper | Application of Electrochemical Impedance Spectroscopy in the Study of Structure and Properties of Composite Materials

Study on electron transport properties of one-dimensional and quasi-one-dimensional disordered systems

Study on transport characteristics of new semiconductor materials and infrared devices

Similar literature

Journal | Research Progress of Lithium Titanate as Anode Material for Lithium Ion Batteries

Periodic preparation of potassium hexatitanate platelets from lithium potassium titanate and process control

Study on high temperature electric field sintering of BaTiO _ 3-based ceramics

Preparation and Characterization of Spinel Lithium Titanate Nanotubes

Newspaper | Kunming Industry and Information Committee went to Zhenjiang to investigate the low-cost lithium titanate industrialization project

Search literature

Mobile HowNet-Minimum Edition-Touch Screen Edition-Search-Customer Service

65438+February 65438+April 13: 40, open in the app.