Abstract:A Raman spectroscopy study has been performed, at room temperature, on the (Bi 0.5 Na 0.5 ) 0.92 Ba 0.08-3x/2 La x TiO 3 lead-free ceramic system (with x = 0, 1, 2, and 3 at.% La). The signature of the Raman spectra showed that the structural properties were noticeably affected by the La 3+ -ions concentration, revealing the
“…The intensive peak at 286 cm −1 is present due to vibrations of TiO 6 octahedra. It can be noticed that this peak splits into two different peaks when the sintering temperature increases, which can be due to different vibrations of Ti–O bonds in Bi 0.5 Na 0.5 TiO 3 and Bi 2 Ti 2 O 7 phases [ 29 ]. Peaks present in the range of 413 to 820 cm −1 are dominated by the oxygen atom vibrations [ 30 , 31 ].…”
Section: Resultsmentioning
confidence: 99%
“…The peak at 860 cm −1 indicated that the oxygen vacancies are present in the BNT-BT samples with 4–10% BT. [ 29 , 32 ] Figure 7 Raman spectra of BNT-BT ceramics after sintering at 1100°C/1 h. …”
Section: Resultsmentioning
confidence: 99%
“…It is shown that the dielectric constant for the pure BNT increases until its broad maximum value at around 320°C, which corresponds to the transition of antiferroelectric to paraelectric phase or temperature of maximum dielectric constant T m [ 35 ]. Another anomaly is noticed in the BNT-BT ceramics in the range from 150°C to 200°C, which is defined as ferroelectric to antiferroelectric phase transition or depolarization temperature T d [ 29 ]. Figure 10 shows the temperature dependence of the dielectric constant for all BNT-BT samples.…”
Section: Resultsmentioning
confidence: 99%
“…The peak at 860 cm −1 indicated that the oxygen vacancies are present in the BNT-BT samples with 4-10% BT. [29,32] SEM micrographs of the fresh fracture of the BNT-BT ceramics after sintering at 1100°C/1 h are shown in figure 8. The image inserted in figure 8a shows the surface of the pure BNT ceramics with well-defined grains and the average size of approximately 1.5 µm.…”
Section: Characterization Of Bnt-bt Ceramicsmentioning
The influence of different processing parameters and various Ba
2+
addition (up to 10 mol%) on the structure and dielectric properties of Bi
0.5
Na
0.5
TiO
3
-BaTiO
3
(BNT-BT) ceramics was investigated. The powders were hydrothermally synthesized in the alkaline environment at 180°C for different time periods. X-ray diffraction confirmed the presence of dominant rhombohedral Bi
0.5
Na
0.5
TiO
3
phase and a small amount of secondary pyrochlore Bi
2
Ti
2
O
7
phase in the pure BNT powders. In addition, one-dimensional Na
2
Ti
2
O
7
structure was also observed in the powder hydrothermally treated for a long time (i.e. 48 h). The amount of secondary pyrochlore phase in the BNT-BT powders increases with the increase of Ba
2+
content. The synthesized powders were pressed into pellets and finally sintered at various temperatures up to 1150°C. High density (more than 90%TD) was obtained in all BNT-BT sintered samples. Optimal sintering parameters were chosen in order to obtain dense ceramics with the optimal phase composition. The temperature dependence of dielectric properties for the BNT-BT ceramics was also studied. Relaxor behaviour of BNT-based ceramics and broad transition peaks are evident in all samples. Dielectric constant up to 400 as well as an acceptable low dielectric loss at temperatures lower than 200°C were obtained in BNT-BT ceramics.
“…The intensive peak at 286 cm −1 is present due to vibrations of TiO 6 octahedra. It can be noticed that this peak splits into two different peaks when the sintering temperature increases, which can be due to different vibrations of Ti–O bonds in Bi 0.5 Na 0.5 TiO 3 and Bi 2 Ti 2 O 7 phases [ 29 ]. Peaks present in the range of 413 to 820 cm −1 are dominated by the oxygen atom vibrations [ 30 , 31 ].…”
Section: Resultsmentioning
confidence: 99%
“…The peak at 860 cm −1 indicated that the oxygen vacancies are present in the BNT-BT samples with 4–10% BT. [ 29 , 32 ] Figure 7 Raman spectra of BNT-BT ceramics after sintering at 1100°C/1 h. …”
Section: Resultsmentioning
confidence: 99%
“…It is shown that the dielectric constant for the pure BNT increases until its broad maximum value at around 320°C, which corresponds to the transition of antiferroelectric to paraelectric phase or temperature of maximum dielectric constant T m [ 35 ]. Another anomaly is noticed in the BNT-BT ceramics in the range from 150°C to 200°C, which is defined as ferroelectric to antiferroelectric phase transition or depolarization temperature T d [ 29 ]. Figure 10 shows the temperature dependence of the dielectric constant for all BNT-BT samples.…”
Section: Resultsmentioning
confidence: 99%
“…The peak at 860 cm −1 indicated that the oxygen vacancies are present in the BNT-BT samples with 4-10% BT. [29,32] SEM micrographs of the fresh fracture of the BNT-BT ceramics after sintering at 1100°C/1 h are shown in figure 8. The image inserted in figure 8a shows the surface of the pure BNT ceramics with well-defined grains and the average size of approximately 1.5 µm.…”
Section: Characterization Of Bnt-bt Ceramicsmentioning
The influence of different processing parameters and various Ba
2+
addition (up to 10 mol%) on the structure and dielectric properties of Bi
0.5
Na
0.5
TiO
3
-BaTiO
3
(BNT-BT) ceramics was investigated. The powders were hydrothermally synthesized in the alkaline environment at 180°C for different time periods. X-ray diffraction confirmed the presence of dominant rhombohedral Bi
0.5
Na
0.5
TiO
3
phase and a small amount of secondary pyrochlore Bi
2
Ti
2
O
7
phase in the pure BNT powders. In addition, one-dimensional Na
2
Ti
2
O
7
structure was also observed in the powder hydrothermally treated for a long time (i.e. 48 h). The amount of secondary pyrochlore phase in the BNT-BT powders increases with the increase of Ba
2+
content. The synthesized powders were pressed into pellets and finally sintered at various temperatures up to 1150°C. High density (more than 90%TD) was obtained in all BNT-BT sintered samples. Optimal sintering parameters were chosen in order to obtain dense ceramics with the optimal phase composition. The temperature dependence of dielectric properties for the BNT-BT ceramics was also studied. Relaxor behaviour of BNT-based ceramics and broad transition peaks are evident in all samples. Dielectric constant up to 400 as well as an acceptable low dielectric loss at temperatures lower than 200°C were obtained in BNT-BT ceramics.
“…Mendez‐Gonzalez et al [ 166 ] used Raman to study of the La‐modified (Bi 0.5 Na 0.5 ) 0.92 Ba 0.08 TiO 3 lead‐free ceramic system. The behavior of the vibrational modes below 200 cm −1 suggests a predominant substitution of the Na + ion by La 3+ at the dodecahedral site of the perovskite structure.…”
This article is an overview of advances in Raman spectroscopy published in 2019 in the Journal of Raman Spectroscopy (JRS) and, in addition, trends over the past decade across journals that have published papers important to the field of Raman spectroscopy. The trends are based on statistical data of article counts obtained from Clarivate Analytic's Web of Science Core Collection by year and by subfield of Raman spectroscopy. Normally in this review, coverage would be provided for presentations involving Raman Spectroscopy at the following four international conferences previously scheduled for this year: the
Mn‐doping is reported to be an effective strategy to obtain better electrical property in bismuth ferrite‐barium titanate (BF‐BT)‐based ceramics, while the property regulation principle and its potential physical mechanism is still poorly understood. For disclose the veil of Mn‐doping enhancing properties, the typical material system BF‐BT–xMnO2 mol% is designed and the effects of Mn‐doping on multilevel structures and external fields stimulated electrical properties are deeply investigated. Mn‐doping induced structure disorder and defect dipoles lead to the formation of nanodomain and the variation of local structure, contributing to intrinsic enhancement of polarization. Especially, electrical properties under different electric and temperature fields reveal that there is a competitive control of domain switching by defects and domain configuration, which is also verified by domain writing technology and switching spectroscopy piezore‐sponse force microscopy. That is, the defect dipoles have pinning effect on domain to hinder domain switching, leading to smaller polarization and indistinctive electrostrain at low fields. While the nanodomain reduces intrinsic coercive field and promotes domain switching, generating much larger polarization and electrostrain at high fields. lt is believed the decoding of domain switching behavior controlled by defect and domain can provide a paradigm to understand the property evolution in chemically modified BF‐BT.
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