Pyroelectric properties of Mn-doped lead zirconate–lead titanate–lead magnesium niobate ceramics

The pyroelectric properties of MnO2 doped compositions in the Pb(Mg1/3Nb2/3)O3–PbTiO3–PbZrO3 system have been investigated for an uncooled pyroelectric infrared detecting application, looking primarily at compositions in the PbZrO3-rich corner of the phase diagram. A processing route from the metal oxides through to the poled ceramic has been developed, which has reduced the size and frequency of defects in the sintered ceramic necessary for producing thin (∼200 μm) ceramic wafers. The electrical properties relevant to the pyroelectric application (dielectric constant, tanδ and pyroelectric coefficient) have been surveyed with respect to composition to produce the best values of the pyroelectric ‘figure of merit’ FD=p/{c′(εεotanδ)1/2} at room temperature. The effects of compositional changes in the ceramic on the two phase transitions from: the ferroelectric low temperature to ferroelectric high temperature phases (FR(LT) to FR(HT)) and the ferroelectric high temperature to paraelectric phases at the Curie point have also been investigated. The consequential changes of the electrical properties are reported. The resisitivity of the ceramic proved insensitive to either the amounts of excess lead or manganese doping levels.