The domain structure of LaNbO4 in the low temperature monoclinic phase

Li, Jian; Huang, Chao; Xu, Guanying Bianca; Wayman, C.M.

doi:10.1016/0167-577x(94)90132-5

Cited by 21 publications

(6 citation statements)

References 1 publication

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“…The distance between lattice fringes was determined to be 2.53(1) Å of the (002) plane and 2.67(1) Å of the (200) plane of domain I and domain II , respectively. The results are consistent with the prototype phase change (4/ m to 2/ m ) in rare-earth niobate compounds with M-fergusonite structure. − The SAED patterns were then collected over area 1 (domain I only) and 2 (domain I and domain II ) for further structural information. The SAED pattern of area 1 shows the single-crystal feature along the (010) direction, and the SAED pattern over the boundary area depicts the overlapped patterns along the (010) direction.…”

Section: Resultssupporting

confidence: 74%

Design of a Sub-6 GHz Dielectric Resonator Antenna with Novel Temperature-Stabilized (Sm_1–xBi_x)NbO₄ (x = 0–0.15) Microwave Dielectric Ceramics

Zhou

et al. 2022

ACS Appl. Mater. Interfaces

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Microwave dielectric ceramics exhibiting a low dielectric constant (ε r ), high quality factor (Q × f), and thermal stability, specifically in an ultrawide temperature range (from −40 to +120 °C), have attracted much attention. In addition, the development of 5G communication has caused an urgent demand for electronic devices, such as dielectric resonant antennas. Hence, the feasibility of optimizing the dielectric properties of the SmNbO4 (SN) ceramics by substituting Bi3+ ions at the A site was studied. The permittivity principally hinges on the contribution of Sm/Bi–O to phonon absorption in the microwave range, while the reduced sintering temperature results in a smaller grain size and slightly lower Q × f value. The expanded and distorted crystal cell indicates that Bi3+ doping effectively regulates the temperature coefficient of resonant frequency (TCF) by adjusting the strains (causing the distorted monoclinic structure) of monoclinic fergusonite besides correlating with the permittivity. Moreover, a larger A-site radius facilitates the acquisition of near-zero TCF values. Notably, the (Sm0.875Bi0.125)NbO4 (SB0.125N) ceramic with ε r ≈ 21.9, Q × f ≈ 38 300 GHz (at ∼8.0 GHz), and two different near-zero TCF values of −9.0 (from −40 to +60 °C) and −6.6 ppm/°C (from +60 to +120 °C), respectively, were obtained in the microwave band. A simultaneous increase in the phase transition temperature (T c) and coefficients of thermal expansion (CTEs) by A-site substitution provides the possibility for promising thermal barrier coating (TBC) materials. Then, a cylindrical dielectric resonator antenna (CDRA) with a resonance at 4.86 GHz and bandwidth of 870 MHz was fabricated by the SB0.125N specimen. The exceptional performance shows that the SB0.125N material is a possible candidate for the sub-6 GHz antenna owing to the advantages of low loss and stable temperature.

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Section: Resultssupporting

confidence: 74%

Design of a Sub-6 GHz Dielectric Resonator Antenna with Novel Temperature-Stabilized (Sm_1–xBi_x)NbO₄ (x = 0–0.15) Microwave Dielectric Ceramics

Zhou

et al. 2022

ACS Appl. Mater. Interfaces

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“…These preparation temperatures are well above the phase transition point, inevitably resulting in twin formation from multiple ferroelastic domains induced as the material cools through the phase transition. Since the crystals in the present study were grown near the phase transition regime, we surmise that the hydrothermal conditions facilitate the growth of the C 2/ c fergusonite-type phase as bulk crystals with much larger single crystalline domains. − Indeed this proved to be the case as the previously reported twinned crystals had domains on the order of tens or hundreds of nanometers, while the crystals grown in this study showed no evidence of significant twin domains over the order of tens to hundreds of microns in the single crystal diffraction studies. Reflection profiles from single crystal diffraction were Gaussian and symmetrical (Figure ), and exhibited narrow peak widths consistent with low mosaicity (fwhm values generally in the range of 0.25–0.45 deg for a 0.1 degree scan width in 2θ).…”

Section: Resultssupporting

confidence: 50%

“…This often precludes high quality structural refinements or causes significant areas of electron density to remain present in the difference electron density maps. Since these microdomains are of a ferroelastic nature they received a great deal of detailed study at the nanoscopic regime. − …”

Section: Introductionmentioning

confidence: 99%

Hydrothermal Chemistry and Growth of Fergusonite-type RENbO₄ (RE = La–Lu, Y) Single Crystals and New Niobate Hydroxides

Fulle

McMillen

Sanjeewa

et al. 2016

Crystal Growth & Design

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A convenient hydrothermal route to high quality single crystals of rare earth orthoniobates RENbO 4 (RE = Y, La−Lu) is reported. The title compounds can be grown as single crystals in sizes exceeding 2 mm for most of the rare earths using 30 M KOH at temperatures of 700 °C and pressures of 2 kbar. Single crystal X-ray diffraction shows that they all form in the fergusonite structure type, and the structures were solved in space group C2/c. Examples based on the largest and smallest rare earth ions in the present study include LaNbO 4 : a = 7.3576( 15) Å, b = 11.538(2) Å, c = 5.2128(10) Å, β = 130.900(3)°, Z = 4, R 1 = 0.0162, wR 2 = 0.0405, and LuNbO 4 : a = 6.9805(6) Å, b = 10.8271(8) Å, c = 5.0406(4) Å, β = 131.676(3)°, Z = 4, R 1 = 0.0178, wR 2 = 0.0489. Although domain structures are clearly present in the bulk crystals, the domains are much larger than normally reported from high temperature growth methods, and individual single domain crystals on the order of 0.1−1 mm in size can be selected. Rocking curves of these crystals have narrow fwhm and are Gaussian shaped. Several new phases were also isolated as part of the development of the crystal growth chemistry and were characterized by single crystal X-ray diffraction including such examples as K 3 YNb 2 O 7 (OH) 2 : P6 3 / mmc, a = 5.9770(12) Å, c = 14.901(2) Å, Z = 2, R 1 = 0.0303, wR 2 = 0.0765 and CsNb 2 O 5 (OH): Fd3̅ m, a = 10.5869(14) Å, Z = 8, R 1 = 0.0336, wR 2 = 0.0741.

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“…The domains arise as a result of the second-order ferroelastic phase transition from the scheelite (4/ m ) to fergusonite (2/ m ) structure. Alternate domains are described by different orientations (I and II) in the monoclinic fergusonite phase, ,,− as illustrated in the adjacent [010] m selected area electron diffraction (SAED) pattern (Figure b). Each alternate domain has a 94.8° rotation, equivalent to the monoclinic β angle.…”

Section: Resultsmentioning

confidence: 99%

Design and Fabrication of a C-Band Dielectric Resonator Antenna with Novel Temperature-Stable Ce(Nb_1–xV_x)NbO₄ (x = 0–0.4) Microwave Ceramics

Zhou

et al. 2022

ACS Appl. Mater. Interfaces

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Vanadium(V)-substituted cerium niobate [Ce(Nb1–x V x )O4, CNVx] ceramics were prepared to explore their structure–microwave (MW) property relations and application in C-band dielectric resonator antennas (DRAs). X-ray diffraction and Raman spectroscopy revealed that CNVx (0.0 ≤ x ≤ 0.4) ceramics exhibited a ferroelastic phase transition at a critical content of V (x c = 0.3) from a monoclinic fergusonite structure to a tetragonal scheelite structure (TF–S), which decreased in temperature as a function of x according to thermal expansion analysis. Optimum microwave dielectric performance was obtained for CNV0.3 with permittivity (εr) of ∼16.81, microwave quality factor (Qf) of ∼41 300 GHz (at ∼8.7 GHz), and temperature coefficient of the resonant frequency (TCF) of ∼ –3.5 ppm/°C. εr is dominated by Ce–O phonon absorption in the microwave band; Qf is mainly determined by the porosity, grain size, and proximity of TF–S; and TCF is controlled by the structural distortions associated with TF–S. Terahertz (THz) (0.20–2.00 THz, εr ∼ 12.52 ± 0.70, and tan δ ∼ 0.39 ± 0.17) and infrared measurements are consistent, demonstrating that CNVx (0.0 ≤ x ≤ 0.4) ceramics are effective in the sub-millimeter as well as MW regime. A cylindrical DRA prototype antenna fabricated from CNV0.3 resonated at 7.02 GHz (|S 11| = −28.8 dB), matching simulations, with >90% radiation efficiency and 3.34–5.93 dB gain.

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The domain structure of LaNbO4 in the low temperature monoclinic phase

Cited by 21 publications

References 1 publication

Design of a Sub-6 GHz Dielectric Resonator Antenna with Novel Temperature-Stabilized (Sm_1–xBi_x)NbO₄ (x = 0–0.15) Microwave Dielectric Ceramics

Design of a Sub-6 GHz Dielectric Resonator Antenna with Novel Temperature-Stabilized (Sm_1–xBi_x)NbO₄ (x = 0–0.15) Microwave Dielectric Ceramics

Hydrothermal Chemistry and Growth of Fergusonite-type RENbO₄ (RE = La–Lu, Y) Single Crystals and New Niobate Hydroxides

Design and Fabrication of a C-Band Dielectric Resonator Antenna with Novel Temperature-Stable Ce(Nb_1–xV_x)NbO₄ (x = 0–0.4) Microwave Ceramics

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The domain structure of LaNbO4 in the low temperature monoclinic phase

Cited by 21 publications

References 1 publication

Design of a Sub-6 GHz Dielectric Resonator Antenna with Novel Temperature-Stabilized (Sm1–xBix)NbO4 (x = 0–0.15) Microwave Dielectric Ceramics

Design of a Sub-6 GHz Dielectric Resonator Antenna with Novel Temperature-Stabilized (Sm1–xBix)NbO4 (x = 0–0.15) Microwave Dielectric Ceramics

Hydrothermal Chemistry and Growth of Fergusonite-type RENbO4 (RE = La–Lu, Y) Single Crystals and New Niobate Hydroxides

Design and Fabrication of a C-Band Dielectric Resonator Antenna with Novel Temperature-Stable Ce(Nb1–xVx)NbO4 (x = 0–0.4) Microwave Ceramics

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Product

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About

Design of a Sub-6 GHz Dielectric Resonator Antenna with Novel Temperature-Stabilized (Sm_1–xBi_x)NbO₄ (x = 0–0.15) Microwave Dielectric Ceramics

Design of a Sub-6 GHz Dielectric Resonator Antenna with Novel Temperature-Stabilized (Sm_1–xBi_x)NbO₄ (x = 0–0.15) Microwave Dielectric Ceramics

Hydrothermal Chemistry and Growth of Fergusonite-type RENbO₄ (RE = La–Lu, Y) Single Crystals and New Niobate Hydroxides

Design and Fabrication of a C-Band Dielectric Resonator Antenna with Novel Temperature-Stable Ce(Nb_1–xV_x)NbO₄ (x = 0–0.4) Microwave Ceramics