Curie temperature of LiNbO3 ceramic

The Curie temperature of LiNbO3 ceramic is the highest among all the piezoelectric ceramic .materials are known so far. Its Curie temperature Tc is up to 1210 ℃. It is the highest known Curie temperature ferroelectric material and piezo rings with silver electrodes is also called high temperature iron.However, it is very difficult to obtain pure LN ceramics, which is mainly due to the fact that piezoelectric transducer for gas sensor has a certain fluidity during the sintering process, such as in the general atmosphere pressure sintering, it is difficult to get a dense ceramic body, and thus the crystallinity and electrical properties of piezo ceramics .which have a greater impact on the pure LN ceramic .piezoelectric constant d33 of pickup piezo transduceris relatively small bismuth-based perovskite compounds such as BiScO3, BiGaO3 , BiInO3 and other Curie points exceed 600 ℃, but it is difficult to synthesize stable ceramic materials.Nitrogen sodium (NaNbO3, abbreviated as NN) is an antiferroelectric material with perovskite structure at room temperature , piezo rings with silver electrodes belongs to the orthorhombic system and has a curie temperature Tc of 365 °C and undergoes seven continuous structural transformations in the temperature range of -100 to 640°C. Potassium niobate (KNbO3, abbreviated as KN) of pickup piezo transducer belongs to perovskite structure compounds, is an important iron .The material has a melting point of 1040°C. and a curie point of Tc of 435°C. Judging from the crystal phase transition, the KN crystal undergoes the following phase transition from high temperature to low temperature. Since KN piezo tube stack has a relatively low melting point, Resulting in a well-crystallized, dense ceramic.Moreover, many other heterophasic phases may also occur during the sintering process, and these phases are deliquescent, affecting the physicochemical stability of KN ceramics.