A process for the preparation of a temperature sensitive resistance to vanadium oxide base

摘要

1,168,107. Thermistors. HITACHI Ltd. 4 Sept., 1967 [14 Sept., 1966], No. 40359/67. Heading H1K. A thermistor is made by heating a mixture of oxides including V 2 O 5 in a reducing atmosphere to produce a mixture including V 2 O x , where x5 and preferably x#4, adding to this mixture a second oxide material which may or may not include V 2 O 5 or V 2 0y, where xy5, and sintering the resulting mixture. The final material essentially comprises microcrystals of V 2 O 4 in a glassy oxide matrix. The thermistor, which may be provided with leads of Pt or Pd, has a resistivity which decreases sharply with increasing temperature over a narrow temperature range. The preferred method of manufacture entails firing, melting and re-cooling a starting mixture of V 2 O 5 , SrCO 3 and (NH 4 ) 2 HPO 4 to form a glassy body containing V 2 O 5 , SrO and P 2 O 5 , and pulverizing this body. A portion of the powder is heated in NH 3 , alcohol, benzene or hydrogen to reduce the V 2 O 5 , and portions of the reduced and unreduced powders are mixed together with water to form a paste which is applied to a pair of leads and dried and shaped. The device is then sintered at 900-1300‹ C. in N 2 , and rapidly cooled. The two powders which are combined to form the paste may, in fact, both be reduced, but to differing degrees. The oxides included with V 2 O 5 in the starting material and the second oxide material are selected from those of P, Sr, Ba, Pb, Ag, Li, Na, K, Be, Mg, Ca, La, Ce, Zr, Zn, Cd, B, Al, Si, Sn, Bi, U, Y, Ge, Fe, Co, Ni, Mn, Ti, Nb, W, Mo, Ta or Cr.