【正文】 ther crystal grain .Below Curie temperature T c, BaTio3 is tetragonal system dielectric, the existence has the spontaneous polarized very strong internal electric field, enable the electron to have the high energy, thus the traversing crystal boundary potential barrier is easy. But above Curie temperature T c, BaTio3 bees the cubic system by the tetragonal system, polarizes vanishing spontaneously, internal electric field vanishing, the electricity is difficult in the traversing potential barrier, therefore above curie warm waste T c, electronic resistivity sharp increase. When two crystal grains contact mutually, crystal grain barrier potential barrier as shown in Figure is potential barrier level thickness, 248。0 sticks the effective dielectric constant ε e ff between with the crystal the relations is: In the formula, n0 is the density of donors。0, the electronic resistivity may write is When the temperature is lower than Curie temperature TC, ε e ff the value is approximately about 104, therefore 248。 V0 lattice vibration frequency。 Slow aberration positive temperature coefficient r (PTC), the critical negative temperature coefficient, the platinum resistor limits the temperature curve like chart 44 curvature 1. 1st, resistance temperature characteristic anti is refers to between the actual resistance value and the resistance body temperature dependent relations, this is one of basic characteristics. PTC switch positive temperature coefficient anti curve. value rises suddenly to some temperature nearby the maximizing. Through the doping .If dopes P b in BaTio3, may cause Tc to the high temperature traverse, mixes in elements and so on S r or S n after BaTio3, may cause TC to the low temperature traverse. May according to need to adjust t Curie temperature TC. The actual resistance number expressed with RT. Is under certain ambient temperature, uses causes the resistance number change not to surpass the resistance value which % survey power actual resistance value is called the zero energy resistance value, or is called does not give off heat the power resistance value (cold resistance value).The actual resistance value size is decided by the resistor material and the geometry shape. If the actual resistance number own temperature has the following relations: NTC In the formula: RT time 11 temperature T actual resistance value。 Element material wet sensitive resistor, for example: Semiconductor G e, Si, Se and C element。 High polymer wet sensitive resistor and so on. The wet sensitive capacitor mainly is the porous Al2O3 material makes as the medium. The wet sensitive transistor divides into the wet sensitive diode and the wet sensitive three levels of tubes. The wet sensitive resistor principle of work and the characteristic 1, the metal oxide pound semiconductor ceramics wet sensitive resistor (1) principle of work porous metal oxide pound semiconductor ceramics, in the crystal plane and the crystal boundary place, very easy to adsorb t drone. Because the water is one strong polar dielectric medium, nearby the h y drone hydrogen atom has the very strong electric field, has the very big electron affinity. When h y drone adheres to stick cohere when the semiconductor ceramics surface, will form the energy level very deep attachment surface acceptor condition, but from semiconductor ceramics surface capture electron, but will form the bound state in the ceramic surface the negative space charge, correspondingly will appear the hole in the near surface layer to accumulate, thus will cause the semiconductor ceramics electronic resistivity depression. Moreover, according to the ion electric conductance principle, the structure not pact semiconductor ceramics crystal grain has certain crevice, reveals the porous capillarity tubular .The drone may adsorbs through this kind of pore between various crystal grains surface and the crystal grain, because adsorbs the e separab