The frequency measurements of dielectric properties in the phase transition range in the Li₀.₀₂Na₀.₉₈NbO₃
Measurement of the temperature, time and frequency changes of dielectric permittivity and dielectric loss in polycrystalline Li₀.₀₂Na₀.₉₈NbO₃ have been carried out. The dielectric permittivity ε has been measured in the temperature range 300K < T < 750 K. The results obtained point out to the...
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| Date: | 1999 |
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Інститут фізики конденсованих систем НАН України
1999
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| Cite this: | The frequency measurements of dielectric properties in the phase transition range in the Li₀.₀₂Na₀.₉₈NbO₃ / W. Smiga // Condensed Matter Physics. — 1999. — Т. 2, № 4(20). — С. 643-648. — Бібліогр.: 10 назв. — англ. |
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| citation_txt | The frequency measurements of dielectric properties in the phase transition range in the Li₀.₀₂Na₀.₉₈NbO₃ / W. Smiga // Condensed Matter Physics. — 1999. — Т. 2, № 4(20). — С. 643-648. — Бібліогр.: 10 назв. — англ. |
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| description | Measurement of the temperature, time and frequency changes of dielectric permittivity and dielectric loss in polycrystalline Li₀.₀₂Na₀.₉₈NbO₃ have been carried out. The dielectric permittivity ε has been measured in the temperature range 300K < T < 750 K. The results obtained point out to the existence of polar microregions above Tc and a complicated domain structure below Tc.
Проведено вимірювання температурних, часових і частотних залежностей діелектричної проникності і діелектричних втрат у полікристалічному Li₀.₀₂Na₀.₉₈NbO₃ в області температур 300K < T < 750 K. Отримані результати вказують на існування полярних мікроскопічних областей вище Tc та складної доменної структури нижче Tc.
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Condensed Matter Physics, 1999, Vol. 2, No. 4(20), pp. 643–648
The frequency measurements of
dielectric properties in the phase
transition range in the Li0.02Na0.98NbO3
W.Śmiga
Institute of Physics and Computer Science, Pedagogical University,
2 Podchora̧żych Str., 30-084 Kraków, Poland
Received September 1, 1998
Measurement of the temperature, time and frequency changes of dielec-
tric permittivity and dielectric loss in polycrystalline Li0.02Na0.98NbO3 have
been carried out. The dielectric permittivity ε has been measured in the
temperature range 300K < T < 750 K. The results obtained point out to
the existence of polar microregions above Tc and a complicated domain
structure below Tc.
Key words: dielectric permittivity, dielectric loss, ferroelectric
PACS: 77.22.-d, 77.22.Ch, 77.84.Dy
1. Introduction
The developing progress of the present-day technique spurs the need of per-
manent research of newer and newer materials as well as the elaboration of their
obtaining. The compounds of ABO3-type with perovskite structure are one of the
most interesting classes of materials. And among them the niobates are of great
interest from the point of view of fundamental research as well as regarding their
applications. The sodium niobate is the best known of all niobates [1,2], which is
an antiferroelectric with very interesting dielectric and semiconducting properties
[3,4]. The properties of ferro- and antiferroelectric solid solutions of lithium niobate
in sodium niobate LixNa1−xNbO3 [5,6] are also very interesting.
The NaNbO3 samples show the following transitions: orthorombic–543K–tetra-
gonal–653K–cubic. Krajnik [7] investigated the phase transition of
NaNbO3:LiNbO3-system by determining the dielectric permittivity in different fields
and at different temperatures. He reported that ferroelectric pseudotetragonal and
orthorombic phases emerged, when LiNbO3 content increased.
The aim of the present paper was to investigate the effect of the electric field
frequency on the temperature and time changes of dielectric permittivity ε and
dielectric loss tan δ.
c© W.Śmiga 643
W.Śmiga
0
500
1000
1500
2000
2500
3000
3500
4000
350 400 450 500 550 600 650 700 750
T [K]
ε
100 Hz
200 Hz
400 Hz
1 kHz
10 kHz
Figure 1. Temperature changes of dielectric permittivity for Li0.02Na0.98NbO3 at
cooling.
2. Experiment
The temperature, frequency and time measurements of electric permittivity were
made by means of a computerized system based on BM 595 RLCG-meter at measur-
ing electric field level 400 V/m. The measurements were performed in the tempera-
ture range 300 K–750 K and in the frequency range 100 Hz–20 kHz at a controlled
rate 4 K/min on cooling. For time dependent measurements, the sample was be-
ing annealed in the temperature of 800 K during 1 hour in order to eliminate the
internal and near-electrode stress. The temperature of the sample was stabilized
with an accuracy of ±0.2 K. The sample used in the experiment had the shape of
a disk with the surface equal to 48 mm2 and the thickness equal to 2.38 mm. The
Li0.02Na0.98NbO3 polycrystal has been obtained by synthesis of Na2CO3, Nb2O5 and
Li2CO3 [6]. The sample was prepared in the Institute of Solid State Physics at the
University of Latvia in Riga.
3. Results
Temperature changes of dielectric permittivity ε and dielectric loss tan δ of the
polycrystal on cooling for different frequencies of the measuring field are presented
in figures 1 and 2. The maximum of dielectric permittivity is observed on cooling at
about 560 K.
It can be noticed, that the maximum value of dielectric permittivity ε decreases
with the increase of the frequency of measuring field. On the other hand, the temper-
ature, at which it occurs, increases with the increase of frequency. Thermal hysteresis
between heating and cooling cycles is equal to 16 K.
644
Frequency measurements
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
290 340 390 440 490 540 590 640 690 740
200 Hz
400 Hz
1K
4K
20K
T [K]
tg d
Figure 2. Temperature changes of dielectric losses for Li0.02Na0.98NbO3 at cool-
ing.
Analysing the temperature dependence of tan δ we can notice the anomaly close
to the temperature of 540 K (this anomaly is well seen especially for low frequencies).
In the whole range of the investigated temperatures the value of tan δ decreases with
the increase of frequency.
The time changes of dielectric permittivity and dielectric loss for
Li0.02Na0.98NbO3 for several temperatures (below and above phase transition) and
frequencies are shown in figures 3 and 4. Strong time dependence of dielectric per-
mittivity in temperature region of 500–580 K was observed. The time changes of ε
(as a dependence ε/ε(t=0) on t) are presented in figure 3. These changes depend both
on temperature and frequency. In the range of phase transition the time changes ε(t)
are the largest. Time changes of dielectric loss tan δ (as a dependence tan δ/ tan δ(t=0)
on t) are presented in figure 4. For tan δ the time changes increase with the increase
of frequency and their values also depend on temperature.
The investigations carried out show that the dielectric permittivity ε and tan δ
change in time according to the logarithmic law [8].
4. Summary
Based on the investigations performed the following conclusions can be drawn:
- the substitution of sodium ions by lithium ions leads to the arising of polar
regions above Tc [9],
- the time changes of dielectric permittivity ε below T c can be connected with
the changes of domain structure [8,10], tending to achieve the stable state,
645
W.Śmiga
e/e(t=0)
0,75
0,80
0,85
0,90
0,95
1,00
530K
0,90
0,92
0,94
0,96
0,98
1,00
400 Hz
2 kHz
10 kHz
577K
0,95
0,96
0,97
0,98
0,99
1,00
0 5000 10000 15000 20000
t [s]
649K
tgd/tgd(t=0)
0,60
0,70
0,80
0,90
1,00
530K
0,80
0,85
0,90
0,95
1,00
577K
0,90
0,95
1,00
0 5000 10000 15000 20000
t [s]
400Hz
2kHz
10 kHz
649K
Figure 3. Time changes of dielectric
permittivity for Li0.02Na0.98NbO3.
Figure 4. Time changes of dielectric
losses for Li0.02Na0.98NbO3.
characterized by the smallest value of free energy, in the material,
- the defects of the lattice and the impurities strongly effect the ε value and
its changes versus the temperature and versus the frequency of the applied
electric field.
Taking into account the latter conclusion the following explanation can be pro-
posed. While annealing the ceramic and depositing electrodes some defects arise.
After cooling some of them are frozen. The most active point defects, which are oxy-
gen vacancies, play the basic role in solid solution LixNa1−xNbO3 and in NaNbO3.
These defects, frozen in cooling process, become the centres of capture for the elec-
tron emitted from the metallic electrodes to the inside of the sample. These centres,
which are being polarized under the effect of the alternating field, give rise to polar
microregions. They contribute to the entire polarization of the sample and cause the
increase of dielectric permittivity value in the cooling process. The interaction of
these microregions leads to the emerging of time dependent dielectric permittivity
as well as to its dependence on the frequency of the measuring field.
646
Frequency measurements
References
1. Megaw H.D. The seven phases of sodium niobate. // Ferroelectrics, 1974, vol. 7, p. 87.
2. Kuś C., Ba̧k W., Ptak W. S., Śmiga W. Antiferroelectric-paraelectric phase transfor-
mation in nonstoichiometric NaNbO3. // Ferroelectrics, 1988, vol. 81, p. 277.
3. Sadel A., von der Mühll R., Ravez J., Chaminade I.P., Hagenmuller P. Synthese
et etude des transitions de phases de ceramiques et de cristaux de composition
Li0.02Na0.98NbO3. // Solid State Commun., 1982, vol. 345, p. 44.
4. Kuś C., Ptak W.S., Śmiga W., Rajewski I.P. Dielektriczeskie i poluprowodnikowyje
swojstwa twerdogo rastwora Na1−xLixNbO3 dla 0 < x < 0.2. // Izv. Akad. Nauk
SSSR, 1991, vol. 55, p. 564 (In Russian).
5. Kuś Cz., Śmiga W., Garbarz B. Zmiany temperaturowe i czasowe przenikalności elek-
trycznej w polikrysztale Li0.04Na0.96NbO3. // Technologia Elektronowa, 1997, p. 222
(In Polish).
6. Kuś Cz., Dambakalne M.J., Brante I.V, Bormanis K., Plaude A.V. Production
and properties of ferroelectrics materials based on NaNbO3 and solid solutions
Na1−xLixNbO3. // Ferroelectrics, 1988, vol. 81, p. 281.
7. Krajnik N.N. Antisegneto i segnetoelektriczeskije swojstwa nekotorych twerdych rast-
worow na osnowie niobata natria. // Izw. Akad. Nauk SSSR, Ser. Fiz., 1958, vol. 22,
No. 12, p. 1492.
8. Kuś C., Jankowska I., Śmiga W., Rajfur Z. The changes of dielectric constant for
polycrystalline samples of LixNa1−xNbO3. // Ferroelektrizität, 1991, vol. 90, p. 133.
9. Śmiga W., Konieczny K., Kuś Cz., Burzyńska M. Dielectric properties of
Li0.003Na0.997NbO3 ceramics. // Ferroelectrics, 1998 (in press).
10. Sadel A., von der Mühll R., Ravez J. Etude optique et couplage ferroelectrique-
ferroelastique de cristaux de composition Li0.02Na0.98NbO3. // Mat. Res. Bull., 1983,
vol. 18, p. 45 (in French).
647
W.Śmiga
Частотні вимірювання діелектричних властивостей
Li0.02Na0.98NbO3 в області фазового переходу
В.Сьміга
Інститут фізики та обчислювальної техніки,
Педагогічний університет,
Польща, 30-084 Краків, вул. Подхоронжих, 1
Отримано 1 вересня 1998 р.
Проведено вимірювання температурних, часових і частотних залеж-
ностей діелектричної проникності і діелектричних втрат у полікри-
сталічному Li0.02Na0.98NbO3 в області температур 300K < T < 750 K.
Отримані результати вказують на існування полярних мікроскопічних
областей вище Tc та складної доменної структури нижче Tc.
Ключові слова: діелектрична проникність, діелектричні втрати,
сегнетоелектрик
PACS: 77.22.-d, 77.22.Ch, 77.84.Dy
648
|
| id | nasplib_isofts_kiev_ua-123456789-120584 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1607-324X |
| language | English |
| last_indexed | 2025-11-30T22:39:42Z |
| publishDate | 1999 |
| publisher | Інститут фізики конденсованих систем НАН України |
| record_format | dspace |
| spelling | Smiga, W. 2017-06-12T11:54:47Z 2017-06-12T11:54:47Z 1999 The frequency measurements of dielectric properties in the phase transition range in the Li₀.₀₂Na₀.₉₈NbO₃ / W. Smiga // Condensed Matter Physics. — 1999. — Т. 2, № 4(20). — С. 643-648. — Бібліогр.: 10 назв. — англ. 1607-324X DOI:10.5488/CMP.2.4.643 PACS: 77.22.-d, 77.22.Ch, 77.84.Dy https://nasplib.isofts.kiev.ua/handle/123456789/120584 Measurement of the temperature, time and frequency changes of dielectric permittivity and dielectric loss in polycrystalline Li₀.₀₂Na₀.₉₈NbO₃ have been carried out. The dielectric permittivity ε has been measured in the temperature range 300K < T < 750 K. The results obtained point out to the existence of polar microregions above Tc and a complicated domain structure below Tc. Проведено вимірювання температурних, часових і частотних залежностей діелектричної проникності і діелектричних втрат у полікристалічному Li₀.₀₂Na₀.₉₈NbO₃ в області температур 300K < T < 750 K. Отримані результати вказують на існування полярних мікроскопічних областей вище Tc та складної доменної структури нижче Tc. en Інститут фізики конденсованих систем НАН України Condensed Matter Physics The frequency measurements of dielectric properties in the phase transition range in the Li₀.₀₂Na₀.₉₈NbO₃ Частотні вимірювання діелектричних властивостей Li₀.₀₂Na₀.₉₈NbO₃ в області фазового переходу Article published earlier |
| spellingShingle | The frequency measurements of dielectric properties in the phase transition range in the Li₀.₀₂Na₀.₉₈NbO₃ Smiga, W. |
| title | The frequency measurements of dielectric properties in the phase transition range in the Li₀.₀₂Na₀.₉₈NbO₃ |
| title_alt | Частотні вимірювання діелектричних властивостей Li₀.₀₂Na₀.₉₈NbO₃ в області фазового переходу |
| title_full | The frequency measurements of dielectric properties in the phase transition range in the Li₀.₀₂Na₀.₉₈NbO₃ |
| title_fullStr | The frequency measurements of dielectric properties in the phase transition range in the Li₀.₀₂Na₀.₉₈NbO₃ |
| title_full_unstemmed | The frequency measurements of dielectric properties in the phase transition range in the Li₀.₀₂Na₀.₉₈NbO₃ |
| title_short | The frequency measurements of dielectric properties in the phase transition range in the Li₀.₀₂Na₀.₉₈NbO₃ |
| title_sort | frequency measurements of dielectric properties in the phase transition range in the li₀.₀₂na₀.₉₈nbo₃ |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/120584 |
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