Piezoelectric Properties of Ca₃NbGa₃Si₂O₁₄ Single Crystal

Abstract

Langasite-type single crystal Ca3NbGa3Si2O14 (CNGS) was grown by the Czochralski technique. Dielectric, elastic and piezoelectric constants of CNGS were measured by the resonance-antiresonance method. At room temperature, dielectric constants ε11 T/ε0 and ε33 T/ε0 were 17.8 and 27.9, respectively. Electromechanical coupling coefficients k 12, k 25 and k 26 were also determined as 10.9, 17.3 and 11.9%, respectively. The measurements were carried out in a temperature range from -30 to 80°C. Temperature coefficients of the dielectric, elastic and piezoelectric constants were obtained. The line-focus-beam and plane-wave ultrasonic material characterization system was employed for measuring bulk acoustic velocities, and longitudinal and transverse wave velocities of 7408.4 m/s and 3136.2 m/s, respectively, in the c-direction uncoupled with piezoelectricity at 23°C were obtained. This was in good agreement with the results determined by the resonance-antiresonance method. The density of CNGS was 4125 kg/m3. All the parameters of the CNGS crystal for bulk and surface acoustic wave applications were determined in this research.

Bridgman growth of langasite‐type piezoelectric crystals

“…The trigonal unit-cell parameters were calculated using the TEROR program [20], according to the peak values of 2θ in the XRPD pattern, where a= 0.809308685 (±0.0001025) nm, c=0.5047688 (±0.0001732) nm and V= 0.28631 nm 3 which were very close to those in Ref. [19]. Fig.…”

“…Chai et al reported that disorder causes higher acoustic losses and also non-uniform mechanical properties, and the ordered crystals have the advantages of a lower Ga 2 O 3 content, high acoustic velocity and low acoustic loss [7]. Among this class ordered compounds, CNGS has the lowest melting point (1350°C or so) [19], which is beneficial for Bridgman growth. Thus CNGS crystal is grown by the modified Bridgman method firstly.…”

“…T. Karki et al found that CNGS crystals grown along the y-axis with Czochralski method were generally prismatic with a clearly defined face of [001] and had plank shape with a thickness of 15mm. They deduced that the crystal growth speed in the c-direction was much slower than in other direction [19]. The top section of the as-grown crystal is shown in figure 3.…”

“…LGS belongs to the trigonal crystal system, point group 32 and space group P321. Single crystals with langasite structure have the general chemicl formula A 3 BC 3 D 2 O 14, they have 4 cation sites in which cations can be substituted by others, resulting in more than 100 langasite family materials that have been identified [4]. Among them, several crystals, such as LGS, Sr (STGS), exhibit large piezoelectric constants, and are regarded as potential substrate materials for SAW and BAW filters [5][6][7][8][9][10].…”

Forecast of Piezoelectric Properties of Crystalline Materials from First Principles Calculation

“…Internal one is nearly twice as larger as the clamped one and it means that the dominated contribution comes from the internal lattice, i.e., atomic positions relaxation after imposing a homogenous strain on the lattice. For Sr 3 Reference [25] The piezoelectric coefficients of SGG have been computed by using the alchemical pseudo-potentials technique. The piezoelectric coefficient e 11 calculated from experimental structure is presented in table IV.…”