Determination of temperature dependency of material parameters for lead-free alkali niobate piezoceramics by the inverse method

作者：Ogo K; Kakimoto K; Weiss M; Rupitsch S J; Lerch R

来源：AIP Advances, 2016, 6(6): 065101.

DOI：10.1063/1.4953327

Sodium potassium niobate (NKN) piezoceramics have been paid much attention as lead-free piezoelectric materials in high temperature devices because of their high Curie temperature. The temperature dependency of their material parameters, however, has not been determined in detail up to now. For this purpose, we exploit the so-called Inverse Method denoting a simulation-based characterization approach. Compared with other characterization methods, the Inverse Method requires only one sample shape of the piezoceramic material and has further decisive advantages. The identification of material parameters showed that NKN is mechanically softer in shear direction compared with lead zirconate titanate (PZT) at room temperature. The temperature dependency of the material parameters of NKN was evaluated in the temperature range from 30 degrees C to 150 degrees C. As a result, we figured out that dielectric constants and piezoelectric constants show a monotonous and isotropic increment with increasing temperature. On the other hand, elastic stiffness constant c(44)(E) of NKN significantly decreased in contrast to other elastic stiffness constants. It could be revealed that the decrement of c(44)(E) is associated with an orthorhombic-tetragonal phase transition. Furthermore, ratio of elastic compliance constants s(44)(E)/s(33)(E) exhibited similar temperature dependent behavior to the ratio of piezoelectric constants d(15)/d(33). It is suspected that mechanical softness in shear direction is one origin of the large piezoelectric shear mode of NKN. Our results show that NKN are suitable for high temperature devices, and that the Inverse Method should be a helpful approach to characterize material parameters under their practical operating conditions for NKN.

• 出版日期2016-6