Ferroelastic transitions in β-BiNbO<sub>4</sub> and β-BiTaO<sub>4</sub>

Sleight, A. W.; Jones, G. A.

doi:10.1107/s0567740875008783

Cited by 31 publications

(29 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, the isolation of both rotamers in case of Bi and La in the crystalline state gives unequivocal evidence that ± at least for the large metal ions ± the two pc rings should rotationally oscillate forth and back around the metal centre in the solution state. 7 a, From an analogous behaviour in Bi and La oxo compounds it has been reasoned that the size of Bi III depends on the degree of the 6 s 2 lone-pair character [6,26]. The absence of coa-lescence phenomena in earlier VT-1 H-NMR studies [22] indicates that obviously the rotation still takes place but at rates slower than the 1 H-NMR time scale [23].…”

Section: A/inset Inmentioning

confidence: 99%

Untitled

Hückstädt

Tutaß

Göldner

et al. 2001

Z. anorg. allg. Chem.

View full text Add to dashboard Cite

Potassium diphthalocyaninato(2±)metallate(III), K[M(pc 2± ) 2 ] (M = Bi, La, Ce, Pr, Sm, Sb, In) has been prepared by melting the metal chloride, iodide or acetate with 1,2-dicyanobenzene in the presence of potassium methylate. Crystallisation with tetra(n-butyl)ammonium bromide or hydroxide (( n Bu 4 N)Br/OH), tetra(n-pentyl)ammonium chloride (( n Pe 4 N)Cl) or bis(triphenylphosphine)iminium halide ((PNP)X; X = Br, I) yields the corresponding red-purple complex salt ( n Bu 4 N)[M(pc 2± ) 2 ] (M = Bi (1), La (3), Ce (2)), ( n Bu 4 N)[M(pc 2± ) 2 ]´x CH 3 OH (M = Bi (5), Pr (6), Sm (7); 0 9 x 9 1), ( n Pe 4 N)[La(pc 2± ) 2 ] (4), ( n Bu 4 N)[Pr(pc 2± ) 2 ]´2 py (10), ( n Bu 4 N)[Sb(pc 2± ) 2 ]´2 thf (11), (PNP) 2 [M(pc 2± ) 2 ]Br2 Et 2 O (M = Sb (12), Bi (13)), and (PNP) 2 [In(pc 2± ) 2 ]I´2 Et 2 O (14). Bronze coloured diphthalocyaninato(1±)metal(III) polyiodide, [M(pc ± ) 2 ]I 2 (M = Sc, Y) has been prepared similarly in the presence of ammonium iodide. Reduction with ( n Bu 4 N)OH provides ( n Bu 4 N)[M(pc 2± ) 2 ]´x CH 3 OH (M = Y (8), Sc (9); 0 9 x 9 1). Spectral properties (UV/VIS/NIR; IR; resonance Raman) of diphthalocyaninates in their different ring oxidation states (2±/2±; 2±/1±; 1±/1±) are discussed. 1±3 crystallise in the tetragonal (P4/ncc), 5±9 in the orthorhombic (Pna2 1 ), 10, 11 in the triclinic (P-1), and 4, 12± 14 in the monoclinic crystal system (4: P2 1 /m; 12: C2/c; 13, 14: P2/c). Ecliptic rotamers with skew angles ranging from 4.1°to 6.0°are found in 1±3, and staggered rotamers with skew angles ranging from 35.8°to 45.0°are found in 4±14. The mean M±N i bond lengths and interplanar distances increase monotonically with the ionic radius of the metal ion. Both distances deviate notably from this linear correlation in the Sb III and Bi III derivatives. The discrepancy is presumably due to the sterical dominance of the ns 2 lone-pair character. The actual size of eight co-ordinated Sb III and Bi III is estimated to be R 8 » 1.02(Sb)/1.11(Bi) A Ê . In every complex salt, the pc ligand is severely distorted from planarity and can adopt domed, saddled, waved and mixed non-planar conformations; the crystal symmetry is the most important factor for the conformational heterogeneity.

show abstract

Section: A/inset Inmentioning

confidence: 99%

Untitled

Hückstädt

Tutaß

Göldner

et al. 2001

Z. anorg. allg. Chem.

View full text Add to dashboard Cite

show abstract

“…BiNbO 4 and BiTaO 4 had two polymorphs of the low-temperature orthorhombic structure and the hightemperature triclinic structure and their irreversible phasetransition temperature was 1005°C and 725°C, respectively [15]. However, the triclinic structure was not obtained in this work when the sintering process conducted at 900°C.…”

Section: Zbs Glass-doped Bi(nb 07 Ta 03 )O 4 Ceramicsmentioning

confidence: 82%

Low-temperature sintering and dielectric properties of the Bi(Nb1−x Ta x )O4 system

Kim

et al. 2007

J Electroceram

View full text Add to dashboard Cite

Low-temperature sintering and dielectric properties of the Bi(Nb 1−x Ta x )O 4 (x=0.1, 0.3, and 0.5) system was investigated as a function of the zinc borosilicate (ZBS) glass content with a view to applying this system to LTCC technology. The addition of 7 wt% ZBS glass ensured a successful sintering below 900°C. The complete solid solution of Bi(Nb, Ta)O 4 with an orthorhombic structure was formed and the high temperature form of Bi(Nb, Ta)O 4 with a triclinic structure was not observed. The second phase of Bi 2 SiO 5 was observed for all compositions. The non-relative liquid phase sintering (NLPS) occurred and the one-stage sintering was conducted. The Q×f values were improved by the addition of Ta. Bi(Nb 0.7 Ta 0.3 )O 4 with 7 wt% ZBS glass sintered at 900°C demonstrated 35.8 in the dielectric constant (ɛ r ), 2,200 GHz in the quality factor (Q×f 0 ), and −48 ppm/°C in the temperature coefficient of resonant frequency (τ f ).

show abstract

“…According to the previous reports, the preparation of BiNbO 4 by solid state synthesis method at 800-850 • C results in the formation of orthorhombic (α) polymorph of BiNbO 4 that is transformed into triclinic β-form at T > 1000 • C [17]. The thermal decomposition of citrate precursors causes appearance of the crystalline BiNbO 4 with a structure similar to its high temperature triclinic polymorph [18] while little is known about its further transformation.…”

Section: Binbomentioning

confidence: 99%

Liquid phase low temperature sintering of niobate and cerate fine powders

Shlyakhtin

Orlov

2006

J Electroceram

View full text Add to dashboard Cite

The efficiency of simultaneous application of chemically-derived starting powders and melt-forming sintering aids in low temperature sintering has been demonstrated. Doping of cryochemically processed BiNbO 4 powders with CuO/V 2 O 5 causes reducing sintering temperatures from 850-900 • C to 700-720 • C. Similar doping of Zn 3 Nb 2 O 8 fine powders allows to obtain ceramics with density 97-98% and Q × F values up to 40 000 GHz at T > 720 • C. The sintering of solution-derived BaCeO 3 powders doped with CuO results in dense ceramics at T = 1000 • C. Morphological evolution during sintering was observed using hot stage SEM. Low temperature liquid phase sintering of fine powders is rather sensitive to the traces of secondary phases and to the micromorphology of starting powders though observed reduction of sintering temperatures is substantially larger than for traditional liquid phase sintering of coarse-grained oxide powders.

show abstract

Ferroelastic transitions in β-BiNbO₄ and β-BiTaO₄

Cited by 31 publications

References 2 publications

Untitled

Untitled

Low-temperature sintering and dielectric properties of the Bi(Nb1−x Ta x )O4 system

Liquid phase low temperature sintering of niobate and cerate fine powders

Contact Info

Product

Resources

About

Ferroelastic transitions in β-BiNbO4 and β-BiTaO4

Cited by 31 publications

References 2 publications

Untitled

Untitled

Low-temperature sintering and dielectric properties of the Bi(Nb1−x Ta x )O4 system

Liquid phase low temperature sintering of niobate and cerate fine powders

Contact Info

Product

Resources

About

Ferroelastic transitions in β-BiNbO₄ and β-BiTaO₄