Polyol-mediated synthesis of Bi-deficient Mg2+-doped sodium bismuth titanate and study of oxide ion migration behavior with functional properties

Pandey

Int J Applied Ceramic Tech

2022

Self Cite

The signature of oxide ion conductivity was perceived in acceptor‐doped (alkaline‐earth metals) Y3GaO6. An acceptor doping of 2%Ca in Y3GaO6 (i.e., Y2.94Ca0.06GaO6) has been found to exhibit a remarkable conductivity. The present work examines the conductivity behavior of 2% Ca‐doped tri‐yttrium gallate (Y2.94Ca0.06GaO6) and also the effect of Mg‐substitution on the phase formation and electrical conductivity of Y2.94Ca0.06GaO6 for its possible application as a solid electrolyte. Polycrystalline dense ceramic samples of Y2.94Ca0.06Ga1−xMgxO6−δ (with x = .00–.04) were fabricated using the conventional solid‐state reaction route. The X‐ray diffraction patterns were recorded to confirm the phase formation. The solid solubility limit of Mg2+ at Ga3+ site was found for x < .03. All the samples were observed to exhibit orthorhombic structure with Cmc21 symmetry (ICSD no.: 155086). Scanning electron microscopy (SEM) morphology reveals dense polygonal grains with vibrant grain boundaries. A significant increase in the conductivity is observed by substituting 1 mol% of Mg2+ at the Ga3+ site of Y2.94Ca0.06Ga1−xMgxO6−δ. However, a further addition of higher dopant concentration of Mg2+ leads to a decline in the electrical conductivity. A relationship between the dopant concentration, phase formation, and structural characterizations has been established to analyze the conductivity behavior.

“…This signifies that the grain boundary plays a significant role in the total resistivity of the sample. A similar type of grain blocking has also been reported in the literature 27 …”

Section: Impedance Analysissupporting

confidence: 82%

Section: Tga Analysismentioning

confidence: 68%

Influence of Mg‐substitution on structural and electrical properties of ion‐conducting Ca‐doped tri‐yttrium gallate

Pandey

Int J Applied Ceramic Tech

2022

Self Cite

“…On the other hand, electron density contour maps provide insight into the relationship between conductivity and structure. 55 Generally, in ABO 3 -type ferroelectric perovskites, the anion conduction pathway is supposed to occur via a hopping mechanism by which evolving anions go via the bottleneck or the beginning of the critical radius of a triangle via socket points which are found between the A-site and B-site ions. 56 According to Singh et al, 55 the oxide ion migrates around the edges of TiO 6 octahedra via −O 1 –O 1 – routes, as well as through interstitials and saddle points within the crystal’s unit cell.…”

Section: Resultsmentioning

confidence: 99%

“… 55 Generally, in ABO 3 -type ferroelectric perovskites, the anion conduction pathway is supposed to occur via a hopping mechanism by which evolving anions go via the bottleneck or the beginning of the critical radius of a triangle via socket points which are found between the A-site and B-site ions. 56 According to Singh et al, 55 the oxide ion migrates around the edges of TiO 6 octahedra via −O 1 –O 1 – routes, as well as through interstitials and saddle points within the crystal’s unit cell. The oxide ion migration mechanism favors the formation of a large number of defects between dopant and oxygen vacancies, which affects the conductivity of the material.…”

Section: Resultsmentioning

confidence: 99%

Studies of Structural, Dielectric, and Impedance Spectroscopy of KBT-Modified Sodium Bismuth Titanate Lead-Free Ceramics

et al. 2022

Lead-free ceramic materials produced from bismuth sodium titanate (Na0.5Bi0.5TiO3, NBT)–bismuth potassium titanate (K0.5Bi0.5TiO3, KBT) have been developed through a solid-state reaction technique. The structural, dielectric, and piezoelectric characteristics of the ceramic materials were analyzed. Based on the XRD investigation, the morphotropic phase boundary (MPB) was determined for the composition (x (%) = 16 and 20). The effects of the KBT phase on the NBT lattice were examined using the charge density distribution. Furthermore, the dielectric properties indicated the presence of a negative dielectric constant (εr′) as a function of frequency between 1 kHz and 2 MHz. Negative permittivity was observed globally in the (1 – x)NBT–xKBT ceramic which reflects the effect of the dielectric resonance. The grain conduction effect is revealed through the complex impedance spectrum in the form of a semicircular arc within the Nyquist plot. In addition, the samples studied revealed a non-Debye relaxation phenomenon. The relaxation time was determined based on the Vogel-Fulcher law for all samples. DC conductivity was carried out on the ceramics material and revealed that the resistance decreases with increasing temperature indicating a negative temperature coefficient of resistance. The AC conductivity as a function of frequency for different temperatures suggests the presence of a thermally activated conduction mechanism. The activation energy has been determined based on the Arrhenius plot of the DC electrical conductivity as well as the relaxation frequency.

“…The frequency dependence of dielectric loss (tanδ) for sintered 0BMN, 1BMN, 3BMN, and 5BMN samples at room temperature was determined, as shown in Figure 6. For 3BMN, the steep decrease in tanδ in the frequency range of 1 kHz and 100 kHz indicated leakage current [28]. During polarization (below 10 kHz), 3BMN showed the maximum loss.…”

Section: Frequency Dependence Of Dielectric Loss (Tanδ)mentioning

confidence: 97%

Weight Loss during Calcination and Sintering Process of Na0.5Bi0.5TiO3–Bi1/2(Mg2/3Nb1/3)O3 Composite Lead-Free Piezoelectric Ceramics

et al. 2021

(1 − x)(Na0.5Bi0.5)TiO3–xBi(Mg2/3Nb1/3)O3 ceramics with x = 0.00 mol.% (0BMN), 0.01 mol.% (1BMN), 0.03 mol.% (3BMN), and 0.05 mol.% (5BMN) were synthesized using a solid-state processing technique. The thermogravimetric analysis (TGA) of uncalcined samples up to 730 °C showed that the maximum weight loss was observed for 3BMN, whereas the minimum weight loss was attributed to the 0BMN sample. After that, calcination was performed at 800 °C for 4 h. The XRD of calcined samples showed the successful formation of the perovskite phase with no impurity phases. 1BMN and 3BMN samples showed some of the lattice strain; however, a morphotropic phase boundary (MPB) existed around x = 0.03 between the rhombohedral and tetragonal structure. The TGA of the green pellets showed weight loss up to the sintering temperature (1100 °C) and during the 3 h holding period. 5BMN showed the maximum weight loss up to sintering temperature, as well as during the holding period, whereas 0BMN displayed the minimum weight loss up to sintering temperature, as well as some weight gain during the holding period. The relative permittivity (εr) was maximum at low frequencies, but the addition of BMN improved the εr. The frequency dependence of dielectric loss (tanδ) showed that the maximum loss was observed for 3BMN at lower frequencies, and 5BMN showed the maximum loss at higher frequency among all samples.