Investigations on thermoelectric power of lanthanum oxide doped ferroelectric sodium vanadate

The thermoelectric power of ferroelectric sodium vanadate doped with different concentrations of lanthanum oxide has been measured in the temperature range covering their transition temperatures. It has been observed that the thermoelectric power increases with temperature, attains maximum value and with further increase in the temperature decreases to zero, indicating Curie temperature of the respective samples; however, it changes the sign for higher temperature. The thermoelectric power of sodium vanadate increases to maximum with increase in doping concentration of lanthanum oxide from 0.025 to 0.1 mol%; however, it decreases for higher concentrations. Pure as well as lanthanum oxide doped sodium vanadate samples showp-type behaviour in the ferroelectric region andn-type behaviour in the paraelectric region.