Structural stability and microwave dielectric properties of (1−x)Ln1/3NbO3–xLn2/3TiO3 (Ln: La, Nd; 0≤x≤0.8)

Bian, Jian; Li, Y.Z.; Yuan, Lü

doi:10.1016/j.matchemphys.2009.02.052

Cited by 13 publications

(8 citation statements)

References 19 publications

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“…It crystallizes into an O aeschynite structure at low temperatures, but transforms into a high‐temperature monoclinic (M) aeschynite structure when temperature is beyond 1230°C . The high‐temperature M phase could be remained at room temperature, achieving good microwave dielectric properties of ε r =22.3, Q × f =49867 GHz and τ f =−55 ppm /°C . By comparison, it is rather difficult to obtain a single O‐phase LTN ceramic as its sintering temperature (∼1325°C) is usually above the phase transition temperature.…”

Section: Introductionmentioning

confidence: 99%

“…7 The high-temperature M phase could be remained at room temperature, achieving good microwave dielectric properties of e r =22.3, Q9f=49867 GHz and s f =À55 ppm /°C. 8 By comparison, it is rather difficult to obtain a single O-phase LTN ceramic as its sintering temperature ( $1325°C) is usually above the phase transition temperature. In our previous work, an O-type LTN ceramic was for the first time obtained by an annealing treatment, exhibiting microwave dielectric properties of e r =48.7, Q9f = 10018 GHz (@5.21 GHz) and s f = 69.7 ppm/°C.…”

Section: Introductionmentioning

confidence: 99%

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Sintering behavior, structural phase transition, and microwave dielectric properties of La_1‐_xZn_xTiNbO_6‐x/2 ceramics

Zhang

Zuo

2017

J Am Ceram Soc

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La1‐xZnxTiNbO6‐x/2 (LZTN‐x) ceramics were prepared via a conventional solid‐state reaction route. The phase, microstructure, sintering behavior, and microwave dielectric properties have been systematically studied. The substitution of a small amount of Zn2+ for La3+ was found to effectively promote the sintering process of LTN ceramics. The corresponding sintering mechanism was believed to result from the formation of the lattice distortion and oxygen vacancies by means of comparative studies on La‐deficient LTN ceramics and 0.5 mol% ZnO added LTN ceramics (LTN+0.005ZnO). The resultant microwave dielectric properties of LTN ceramics were closely correlated with the sample density, compositions, and especially with the phase structure at room temperature which depended on the orthorhombic‐monoclinic phase transition temperature and the sintering temperature. A single orthorhombic LZTN‐0.03 ceramic sintered at 1200°C was achieved with good microwave dielectric properties of εr~63, Q×f~9600 GHz (@4.77 GHz) and τf ~105 ppm/°C. By comparison, a relatively high Q × f~80995 GHz (@7.40 GHz) together with εr~23, and τf ~−56 ppm/°C was obtained in monoclinic LTN+0.005ZnO ceramics sintered at 1350°C.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sintering behavior, structural phase transition, and microwave dielectric properties of La_1‐_xZn_xTiNbO_6‐x/2 ceramics

Zhang

Zuo

2017

J Am Ceram Soc

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“…High Q × f determines the selectivity of the signals and near zero TCF ensures the temperature stability of the resonator [6]. A-site deficient perovskites have been studied for their ionic conductivity by several researchers; however, less attention has been given to their dielectric properties [7,8]. It has been reported that in Li-doped La 2/3 TiO 3 ceramics, ionic * E-mail: dryaseeniqbal@yahoo.co.uk conductivity is due to Li-ion migration via vacancy formation [9].…”

Section: Introductionmentioning

confidence: 99%

“…La 2/3 TiO 3 and Nd 2/3 TiO 3 are A-site deficient perovskites with one-third of A-site vacant. In La 2/3 TiO 3 , A(1) sites are fully occupied by La +3 cations, whereas A(2) sites are partially occupied by vacancies and La +3 ions [7]. La 2/3 TiO 3 has a high dielectric constant of 90 with Q × f greater than 15000 GHZ but with a positive temperature co-efficient of resonant frequency ∼190 ppm/°C [4].…”

Section: Introductionmentioning

confidence: 99%

Phase, microstructure and microwave dielectric properties of A-site deficient (La, Nd)_2/3TiO₃ perovskite ceramics

Saleem

Iqbal

Qin

et al. 2015

Materials Science-Poland

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La, Nd) 2/3 TiO 3 ceramics were prepared through a conventional solid state mixed oxide route. For phase and microstructure analysis, XRD and SEM were used, respectively. Microwave dielectric properties were measured using a network analyzer. XRD patterns revealed the formation of the parent (La, Nd) 2/3 TiO 3 phase along with (La, Nd) 4 Ti 9 O 24 as a secondary phase. The microstructure consisted of rectangular and needle shaped grains, which decreased in size from 4 µm to 2 µm with an increase in sintering temperature from 1300°C to 1350°C. Decrease in grain size caused an increase in density of the samples from 4.81 g/cm 3 to 5.17 g/cm 3 . Microwave dielectric properties of the samples calcined and sintered in air atmosphere were ε r = 40.35, Q × f = 3499 GHz and τ f = 0 ppm/°C, whereas for a sample calcined in nitrogen and sintered in air they were ε r = 40.18, Q × f = 4077 GHz and τ f = +4.9 ppm/°C, respectively.

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“…The rare earth ions are distributed within alternate (001) planes doubling the c ‐parameter. La 1/3 NbO 3 has higher dielectric constant (>130) compared with the titanic counterpart 12 . We have studied the structural evolution and microwave dielectric properties of sodium‐doped La 1/3 NbO 3 (La (1− x )/3 Na x NbO 3 ) 13 .…”

Section: Introductionmentioning

confidence: 99%

Structure and Dielectric Properties of A-Site-Deficient Perovskite La(1−x)/3AgxNbO3 (0≤x≤0.25) Ceramics

Guo

Bian

Wang

2010

Journal of the American Ceramic Society

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The crystal structure and dielectric properties of the A-sitedeficient perovskites La (1Àx)/3 Ag x NbO 3 were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), network analyzer, and impedance analyzer. XRD results showed that no secondary phase was observed in all samples. The crystal structure at room temperature changed from orthorhombic (0rxr0.16) via tetragonal (x 5 0.20) to pseudocubic (x 5 0.25) symmetry with the increase of x. The dielectric constant (e r ) and temperature coefficient of resonant frequency (s f ) of La (1Àx)/3 Ag x NbO 3 ceramic increased with the increase of x due to the decrease of tilting angle of NbO 6 -octahedron. Whereas the quality factor (Q Â f) decreased with increasing silver content as result of the decrease of A-site cation/vacancy ordering. Complex impedance analysis and the dielectric properties measured at low frequency showed that the dielectric loss in La (1Àx)/3 Ag x NbO 3 at low frequency was mainly caused by the silver ionic conduction, and that the composition of x 5 0.13 exhibited largest ionic conductivity and hence highest dielectric loss at low frequency. However, the dielectric loss originated from the ionic conductivity decreased with increasing frequency. Vacancy concentration and ionic conductivity in compounds would affect the order-disorder phase transformation for A-site-deficient perovskites. For the composition with higher ionic conductivity, it would undergo order-disorder phase transformation at much lower temperature. Meanwhile, the ionic conductivity or dielectric loss at low frequency increased with the increase of temperature because of the decrease in cations ordering.

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Structural stability and microwave dielectric properties of (1−x)Ln1/3NbO3–xLn2/3TiO3 (Ln: La, Nd; 0≤x≤0.8)

Cited by 13 publications

References 19 publications

Sintering behavior, structural phase transition, and microwave dielectric properties of La_1‐_xZn_xTiNbO_6‐x/2 ceramics

Sintering behavior, structural phase transition, and microwave dielectric properties of La_1‐_xZn_xTiNbO_6‐x/2 ceramics

Phase, microstructure and microwave dielectric properties of A-site deficient (La, Nd)_2/3TiO₃ perovskite ceramics

Structure and Dielectric Properties of A-Site-Deficient Perovskite La(1−x)/3AgxNbO3 (0≤x≤0.25) Ceramics

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Structural stability and microwave dielectric properties of (1−x)Ln1/3NbO3–xLn2/3TiO3 (Ln: La, Nd; 0≤x≤0.8)

Cited by 13 publications

References 19 publications

Sintering behavior, structural phase transition, and microwave dielectric properties of La1‐xZnxTiNbO6‐x/2 ceramics

Sintering behavior, structural phase transition, and microwave dielectric properties of La1‐xZnxTiNbO6‐x/2 ceramics

Phase, microstructure and microwave dielectric properties of A-site deficient (La, Nd)2/3TiO3 perovskite ceramics

Structure and Dielectric Properties of A-Site-Deficient Perovskite La(1−x)/3AgxNbO3 (0≤x≤0.25) Ceramics

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Sintering behavior, structural phase transition, and microwave dielectric properties of La_1‐_xZn_xTiNbO_6‐x/2 ceramics

Sintering behavior, structural phase transition, and microwave dielectric properties of La_1‐_xZn_xTiNbO_6‐x/2 ceramics

Phase, microstructure and microwave dielectric properties of A-site deficient (La, Nd)_2/3TiO₃ perovskite ceramics