Abstract
Calcium yttrium aluminate (CaYAl3O7) crystal was grown and characterized in detail for high temperature piezoelectric sensors for the first time. The thermal properties of the CaYAl3O7 (CYAM) crystal were investigated systematically. In particular, the CYAM crystal exhibits considerably high resistivity along X- and Z- direction in the order of 6.96 × 107 Ω·cm and 2.86 × 108 Ω·cm at 600 °C, respectively. The temperature dependence of the electromechanical properties of CYAM crystal were investigated over the temperature range of 25–500 °C. The high thermal stability of piezoelectric properties together with its high electrical resistivity, makes CaYAl3O7 crystal a promising candidate for high temperature piezoelectric applications.
Highlights
Electromechanical devices have been designed and extensively used in various electronic devices such as actuators, sensors, and transducers
From the perspective of practical application, developing lead-free piezoelectric materials with the merits of high electrical resistivity, low dielectric loss, large piezoelectric coefficient and high temperature stability are desirable for wide range of high-temperature sensor applications [5,6,7,8]
Melilite crystals with formula of ABC3 O7, which belong to the tetragonal system with space group of P421 m, has attracted much attention in high temperature piezoelectric investigations
Summary
Electromechanical devices have been designed and extensively used in various electronic devices such as actuators, sensors, and transducers. CaYAl3 O7 (abbreviated as CYAM) single crystal, a member of the melilite family, possesses a high melting point of around 1630 ◦ C with no phase transitions below the melting point [18]. In view of the common physical properties, aluminate always possesses higher melting point and larger electrical resistivity than gallium oxide of the same type, which means that CYAM crystal may exhibit better piezoelectric performance and be more competitive for high temperature piezoelectric applications. In recent years, this compound has been studied for long lasting phosphorescence by doping Ce and Eu [19,20]. The temperature dependence of the electrical resistivity, dielectric, piezoelectric, elastic constants and electromechanical coupling coefficient were investigated in the range of 25–500 ◦ C
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