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The piezoelectric, pyroelectric, dielectric and elastic properties of single crystal LiNb0.1Ta0.9O3
Journal of Crystal Growth 79 (1986) 527—529 North-Holland, Amsterdam
527
THE PIEZOELECTRIC, PYROELECURIC, DIELECTRIC AND ELASTIC PROPERTIES OF SINGLE CRYSTAL LiNb01Ta09O3 WANG Hong and WANG Ming Institute of Crystal Materials, Shandong University, Jinan, Shandong People’s Rep. of China
Single crystals of LiNb01Ta09O3 have been grown by the Czochralski method. The piezoelectric, pyroelectnc, dielectric and elastic constants were measured at room temperature. The values of these constants are near those of LiTaO3.
1. Introduction A complete series of solid solutions exist in the LiNbO3—LiTaO3 pseudo-binary system [1]. Since LiTaO3 and LiNbO3 having strong piezoelectric and electro-optic properties coupled with high mechanical Q, they have been widely used in ultrasonic and electro-optic devices [2]. It is interesting,oftherefore, to investigate the physical properties their solid solutions, LiNb~Ta 1 X03. In the present work, a single crystal of LiNb01Ta09O3 was grown by the Czochralski method, the piezoelectric, dielectric, pyroelectric and elastic constant have been determined and compared with those of LiNbO3 and LiTaO3. The result shows that the value of these constants of LiNb01Ta09O3 are between those of LiNbO3 and LiTaO3. 2. Measurement and results
According to the 1949 IRE standards on piezoelectric crystals [3], the axes X, Y and Z form a right-handed Cartesian system, with the X axis parallel to one of the a axis, Z axis parallel to c axis and V axis perpendicular to X and Z axes. Specimens with two parallel faces were cut from the boule. The faces were oriented by means of the X-ray diffraction method to within2, 0.10. and The surface area was larger than 5 x 7mm the thickness about 0.5 mm. X-, Y- and Z-cut plates were fabricated. In addition a rectangular bar with its length along the X axis and with electrodes applied to the Z faces was also prepared. The length of this bar was much larger than the transverse dimension. The electrodes used were gold, deposited on the crystal plates by evaporation in a vacuum of about 5 Torr. i0 By means of liquid immersion method, the density was determined to be p = 7.348 g/cm3.
LiNb 0 1Tao.9°3exhibits trigonal symmetry (class 3m) and has six independent elastic constants C~, C~, C~, C~, C~ and C~, two dielectric constants et~and e~3,four piezoelectric constants e15, e22, e31 and e33, and a pyroelectric constant A. 2.1. Specimen preparation Single crystals of LiNb01Ta09O3 grown by the Czochralski method have a slightly yellow colour, Polarization under 10—20 V/cm for 8 h after growth, produced single domain crystals.
2.2. Dielectric constants The dielectric constants were determined from capacitance measurement of plates with full electrodes, using a CO-il conductivity and capacitance bridge. At frequencies well above any of the strong resonances, the constant e33 was obtained from a Z-cut plate, and r~from either an X-cut or a V-cut. At very low frequencies, well below any strong resonances, the constants e~and af~ were obtained. The results are shown in table 1. The dielectric constants e~’~ for LiNbO3, LiTaO3
0022-0248/86/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)
Wang Hong, Wang Ming / Properties of single crystal LiNb
528
01 Ta0 ~
Tablel Constants of LiNb01Ta09O3 (room temperature)
~ ,..
________________________
LiNb01Ta09O3 Dielectric constants
e~ 533
e~ e3 Elastic constants 2 XIII” N/rn
C~ C,~ C~ C,~ C~ C~
Piezoelectric constants 2 xC/rn Density 3 kg/rn3 x i0
52.1 45.8 40.5 43.5
E
LiNbO3
LiTaO3
‘~
[41
141
.520
84 30 44 29
2.32 0.48 0.80 0.022 2.67 0.94
30~
51 45 41 43
o .
‘~
°
x
°
x
o
0
10 ~
D
20
40
D
2.03 0.53 0.75 0.09 2.45 0.60
2.33 0.47 0.80 —0.11 2.75 0.94
100 LT X LNT a LN Fig. 2. Pyroelectric constant A of LN, LT, and LiNb 01Ta09O3
e~5 2.64 e22 e 2.24 3~ —0.001 e33 1.78
3.7 2.5 0.2 1.3
2.6 1.6 0.0 1.9
versus T.
p
4.7
7.45
trodes a Z-cut The plate pyroelectric in the temperature range 0°C toon 100°C. constants of
7.348
00
~
‘r
6b 1°C)
80
o
LiNbO 3 and LiTaO3 were also measured for comparison. The results are shown in fig. 2.
and LiNb01Ta09O3 were measured in the temperature range 0—100°Cand the results are shown in fig. 1. The LiNbO3 and LiTaO3 samples were from the Department of Physics, Shandong University. The value of ~ for LiTaO3 is slightly larger than that reported by Warner [4]. 2.3. Pyroelectric constants The pyroelectric constant was determined by the electric charge integral method with full elec-
60
40
w
0 x
0
x
X0
0
~
~
~
~
~
D
0 x
0 ~
0 X
~
~
0
0
0
0
20
2.4. Piezoelectric and elastic constants The piezoelectnc and elastic constants were determined by the transmission circuit method, according to the IRE standard on piezoelectric crystals [3]. Fig. 3 shows the schematic diagram of the system for measuring the resonant and antiresonant frequencies of a plate. By using the procedure described in ref. [4], all the piezoelectric and elastic constants were obtained from measuring the resonant and anti-resonant frequencies of various oriented plates. The results are shown in table 1.
PLATE UNDER TEST signal Generator
20
40
60 T
1°C)
80
1
Brid~ej
~
Detector HFJ-8
100 0
LT
x LNT
LN Fig. 1. Dielectric constant
~
sJ3 of LN, LT and LiNb01Ta09O3 versus T.
[Electronic Counter
E324
Fig. 3. System for measuring resonant and antiresonant frequency.
Wang Hong Wang Ming / Properties of single crystal LiNb
0, Ta0 903
3. Conclusions The dielectric, pyroelectric, piezoelectric and elastic constants of LiNb01Ta 0903 have been determined in this paper. The values of these constants are near those of LiTaO3.
529
Shanghai Jiaotong University, for enlightening and stimulating discussions. We are grateful to Mr. Meng Xiangling and his group for preparing the crystals.
References [1] T.
Acknowledgement The authors are indebted to Professor Zhang Zhungyan of the Department of Applied Physics,
Fukuda and H. Hirano, J. Crystal Growth 35 (1976) 127. [21 K. Nassau, H.J. Levinstein and G.N. Lioacono, J. Phys. Chem. Solids 27 (1966) 983.
[3] Standards on Piezoelectric Crystals, Proc. IRE 14, Si (1949) 1378. [4] A.W. Warner, M. Onoe and G.A. Coquin, J. Acoust. Soc. ~.
42 (1967) 1223.
527
THE PIEZOELECTRIC, PYROELECURIC, DIELECTRIC AND ELASTIC PROPERTIES OF SINGLE CRYSTAL LiNb01Ta09O3 WANG Hong and WANG Ming Institute of Crystal Materials, Shandong University, Jinan, Shandong People’s Rep. of China
Single crystals of LiNb01Ta09O3 have been grown by the Czochralski method. The piezoelectric, pyroelectnc, dielectric and elastic constants were measured at room temperature. The values of these constants are near those of LiTaO3.
1. Introduction A complete series of solid solutions exist in the LiNbO3—LiTaO3 pseudo-binary system [1]. Since LiTaO3 and LiNbO3 having strong piezoelectric and electro-optic properties coupled with high mechanical Q, they have been widely used in ultrasonic and electro-optic devices [2]. It is interesting,oftherefore, to investigate the physical properties their solid solutions, LiNb~Ta 1 X03. In the present work, a single crystal of LiNb01Ta09O3 was grown by the Czochralski method, the piezoelectric, dielectric, pyroelectric and elastic constant have been determined and compared with those of LiNbO3 and LiTaO3. The result shows that the value of these constants of LiNb01Ta09O3 are between those of LiNbO3 and LiTaO3. 2. Measurement and results
According to the 1949 IRE standards on piezoelectric crystals [3], the axes X, Y and Z form a right-handed Cartesian system, with the X axis parallel to one of the a axis, Z axis parallel to c axis and V axis perpendicular to X and Z axes. Specimens with two parallel faces were cut from the boule. The faces were oriented by means of the X-ray diffraction method to within2, 0.10. and The surface area was larger than 5 x 7mm the thickness about 0.5 mm. X-, Y- and Z-cut plates were fabricated. In addition a rectangular bar with its length along the X axis and with electrodes applied to the Z faces was also prepared. The length of this bar was much larger than the transverse dimension. The electrodes used were gold, deposited on the crystal plates by evaporation in a vacuum of about 5 Torr. i0 By means of liquid immersion method, the density was determined to be p = 7.348 g/cm3.
LiNb 0 1Tao.9°3exhibits trigonal symmetry (class 3m) and has six independent elastic constants C~, C~, C~, C~, C~ and C~, two dielectric constants et~and e~3,four piezoelectric constants e15, e22, e31 and e33, and a pyroelectric constant A. 2.1. Specimen preparation Single crystals of LiNb01Ta09O3 grown by the Czochralski method have a slightly yellow colour, Polarization under 10—20 V/cm for 8 h after growth, produced single domain crystals.
2.2. Dielectric constants The dielectric constants were determined from capacitance measurement of plates with full electrodes, using a CO-il conductivity and capacitance bridge. At frequencies well above any of the strong resonances, the constant e33 was obtained from a Z-cut plate, and r~from either an X-cut or a V-cut. At very low frequencies, well below any strong resonances, the constants e~and af~ were obtained. The results are shown in table 1. The dielectric constants e~’~ for LiNbO3, LiTaO3
0022-0248/86/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)
Wang Hong, Wang Ming / Properties of single crystal LiNb
528
01 Ta0 ~
Tablel Constants of LiNb01Ta09O3 (room temperature)
~ ,..
________________________
LiNb01Ta09O3 Dielectric constants
e~ 533
e~ e3 Elastic constants 2 XIII” N/rn
C~ C,~ C~ C,~ C~ C~
Piezoelectric constants 2 xC/rn Density 3 kg/rn3 x i0
52.1 45.8 40.5 43.5
E
LiNbO3
LiTaO3
‘~
[41
141
.520
84 30 44 29
2.32 0.48 0.80 0.022 2.67 0.94
30~
51 45 41 43
o .
‘~
°
x
°
x
o
0
10 ~
D
20
40
D
2.03 0.53 0.75 0.09 2.45 0.60
2.33 0.47 0.80 —0.11 2.75 0.94
100 LT X LNT a LN Fig. 2. Pyroelectric constant A of LN, LT, and LiNb 01Ta09O3
e~5 2.64 e22 e 2.24 3~ —0.001 e33 1.78
3.7 2.5 0.2 1.3
2.6 1.6 0.0 1.9
versus T.
p
4.7
7.45
trodes a Z-cut The plate pyroelectric in the temperature range 0°C toon 100°C. constants of
7.348
00
~
‘r
6b 1°C)
80
o
LiNbO 3 and LiTaO3 were also measured for comparison. The results are shown in fig. 2.
and LiNb01Ta09O3 were measured in the temperature range 0—100°Cand the results are shown in fig. 1. The LiNbO3 and LiTaO3 samples were from the Department of Physics, Shandong University. The value of ~ for LiTaO3 is slightly larger than that reported by Warner [4]. 2.3. Pyroelectric constants The pyroelectric constant was determined by the electric charge integral method with full elec-
60
40
w
0 x
0
x
X0
0
~
~
~
~
~
D
0 x
0 ~
0 X
~
~
0
0
0
0
20
2.4. Piezoelectric and elastic constants The piezoelectnc and elastic constants were determined by the transmission circuit method, according to the IRE standard on piezoelectric crystals [3]. Fig. 3 shows the schematic diagram of the system for measuring the resonant and antiresonant frequencies of a plate. By using the procedure described in ref. [4], all the piezoelectric and elastic constants were obtained from measuring the resonant and anti-resonant frequencies of various oriented plates. The results are shown in table 1.
PLATE UNDER TEST signal Generator
20
40
60 T
1°C)
80
1
Brid~ej
~
Detector HFJ-8
100 0
LT
x LNT
LN Fig. 1. Dielectric constant
~
sJ3 of LN, LT and LiNb01Ta09O3 versus T.
[Electronic Counter
E324
Fig. 3. System for measuring resonant and antiresonant frequency.
Wang Hong Wang Ming / Properties of single crystal LiNb
0, Ta0 903
3. Conclusions The dielectric, pyroelectric, piezoelectric and elastic constants of LiNb01Ta 0903 have been determined in this paper. The values of these constants are near those of LiTaO3.
529
Shanghai Jiaotong University, for enlightening and stimulating discussions. We are grateful to Mr. Meng Xiangling and his group for preparing the crystals.
References [1] T.
Acknowledgement The authors are indebted to Professor Zhang Zhungyan of the Department of Applied Physics,
Fukuda and H. Hirano, J. Crystal Growth 35 (1976) 127. [21 K. Nassau, H.J. Levinstein and G.N. Lioacono, J. Phys. Chem. Solids 27 (1966) 983.
[3] Standards on Piezoelectric Crystals, Proc. IRE 14, Si (1949) 1378. [4] A.W. Warner, M. Onoe and G.A. Coquin, J. Acoust. Soc. ~.
42 (1967) 1223.