Thermal and electromechanical properties of melilite-type piezoelectric single crystals

Abstract

Melilite-type crystals, including Ca2Ga2SiO7, Ca2MgSi2O7, and CaNdGa3O7, were successfully grown by the Czochralski technique. Thermal properties were investigated and full matrices of electromechanical constants of these melilite crystals were evaluated by impedance method, with d14 being on the order of 5.3-9.3 pC/N. The relationship between microstructure and electromechanical properties of the three kinds of crystals was established, in order to explore the piezoelectric origin and further optimize the piezoelectric properties. The distortion of eight-fold antiprisms and the distortion/rotation of tetrahedrons were thought to contribute to the piezoelectric d14 and d36, respectively. In addition, the layered structure leads to strong anisotropic behavior, accounts for the high resistivity along Z direction in Ca2MgSi2O7, while the disordered structure accounts for the degraded resistivity in CaNdGa3O7. The properties at elevated temperature were investigated, where the elastic constants show high thermal stability over the range of 25-500 C, with minimal variation of 6%. Publication DetailsShen, C., Zhang, S., Cao, W. Melilite-type crystals, including Ca 2 Ga 2 SiO 7 , Ca 2 MgSi 2 O 7 , and CaNdGa 3 O 7 , were successfully grown by the Czochralski technique. Thermal properties were investigated and full matrices of electromechanical constants of these melilite crystals were evaluated by impedance method, with d 14 being on the order of 5.3-9.3 pC/N. The relationship between microstructure and electromechanical properties of the three kinds of crystals was established, in order to explore the piezoelectric origin and further optimize the piezoelectric properties. The distortion of eight-fold antiprisms and the distortion/rotation of tetrahedrons were thought to contribute to the piezoelectric d 14 and d 36 , respectively. In addition, the layered structure leads to strong anisotropic behavior, accounts for the high resistivity along Z direction in Ca 2 MgSi 2 O 7 , while the disordered structure accounts for the degraded resistivity in CaNdGa 3 O 7 . The properties at elevated temperature were investigated, where the elastic constants show high thermal stability over the range of 25-500 C, with minimal variation of 6%. V C 2015 AIP Publishing LLC. [http://dx

Supersonic propagation of lattice energy by phasons in fresnoite

“…In light of fresnoite’s piezoelectricity 18,19 , it would be interesting to explore whether electric-field-induced strains produce a Q -rotation effect or in some way modify the supersonic phasons. Melilite, a related piezoelectric mineral with a similar incommensurate modulation 37 , has modulation wave vectors (phasons) that vary linearly with temperature 38 . At the other extreme, it would also be interesting to explore phasons in mullite, which has a very stable (rigid) incommensurate structure that persists to higher temperatures, all the way until melting 39–41 .…”

Strontium-substituted calcium magnesium silicate single crystals for high-temperature piezoelectric applications

“…At room temperature, the electric resistivity µ of the CSMS30 crystal exceeded a measuring limit (over 10 13 ³ cm at least). Shen et al 19) reported that the µ at 250°C of the CMS crystal is in the 10 12 ³ cm order while, at room temperature, it could not be measured due to ultrahigh values. In this study, we substituted Ca 2+ by Sr 2+ in the CMS crystal.…”

“…The data of CMS are reported in Ref. 19). We determined the dB 31 by the resonance and anti-resonance method.…”

“…Single crystals of calcium magnesium silicate Ca 2 MgSi 2 O 7 (CMS), also known as the mineral akermanite, are grown from a melt with stoichiometric composition by employing the Czochralski (Cz) method. 18), 19) The CMS crystal shows high d 36 , above 4 pC/N, 19) however, a commensurate-incommensurate phase transition occurs around 85°C, 20) when the d 36 value drops. Although the strontium substitution into CMS decrease the phase transition's temperature, 21) no report about substitution effect on piezoelectric property have been conducted.…”

Effects of aluminum substitution on the structure and electric properties of langasite family crystals

“…However, bulk growth of GaPO 4 crystals is very difficult , while Re Ca 4 O(BO 3 ) 3 crystals have very low crystal symmetries (monoclinic m) and then show pyroelectricity . Recently, gehlenite Ca 2 Al 2 SiO 7 and related crystals in the melilite group have been the subject of much study, because they exhibit piezoelectricity without any accompanying pyroelectricity . The crystals also have very clear cleavage planes, which is a matter of concern for target applications in combustion pressure sensors.…”