Phase equilibria in the system BaO-GeO2

Guha, J. P.

doi:10.1007/bf00569296

Cited by 6 publications

(5 citation statements)

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“…In the literature [11,12] the possibility of formation of other polymorphic phases as well as other phases such as Ba 2 GeO 4 were noted in BaO-GeO 2 system. Repeated grinding and high temperature reactions did not reduce this unknown phase.…”

Section: Resultsmentioning

confidence: 99%

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SECOND PHASE (BaGeO[sub 3], BaSiO[sub 3]) NANOCOLUMNS IN YBa[sub 2]Cu[sub 3]O[sub 7−x] FILMS

Varanasi¹,

Reichart²,

Burke³

et al. 2010

AIP Conference Proceedings

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YBa 2 Cu 3 O 7-x (YBCO) films with BaGeO 3 (BGeO), BaSiO 3 (BSiO) second phase additions were processed by pulsed laser deposition. Sectored targets with BGO or BSiO wedges as well as pre-mixed targets of YBCO, BGeO or BSiO with appropriate compositions were used to deposit YBCO+BGeO and YBCO+BSiO films on (100) single crystal LaAlO 3 substrates. The cross-sectional transmission electron micrographs showed the presence of 20 nm diameter nanocolumns in the YBCO films of both the compositions. However, the critical transition temperature (T c ) of the films was found to significantly decrease. As a result, the critical current density (J c ) in applied magnetic fields was suppressed. The YBCO+BGeO and YBCO+BSiO films made with lower concentrations of additions showed slight improvement in T c indicating that the substitution of Ge and Si in the lattice is possibly responsible for the T c depression. This study shows that in addition to the ability to form nanocolumns, the chemical compatibility of BaSnO 3 (BSO) and BaZrO 3 (BZO) as observed in YBCO+BSO and YBCO+BZO is critical to process high J c YBCO films

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Section: Resultsmentioning

confidence: 99%

“…It also has a high temperature orthorhombic form [11,12]. It also has a high temperature orthorhombic form [11,12].…”

Section: Bageomentioning

confidence: 99%

SECOND PHASE (BaGeO[sub 3], BaSiO[sub 3]) NANOCOLUMNS IN YBa[sub 2]Cu[sub 3]O[sub 7−x] FILMS

Varanasi¹,

Reichart²,

Burke³

et al. 2010

AIP Conference Proceedings

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“…Green bodies of 3 require temperatures above 1200 °C to achieve comparable densities. Even sintering temperatures close to the melting point (1280 °C [9]) and a dwelling time of 10 h or longer leads to ceramics with a relative density of only 81 %. Ceramics sintered below 1250 °C consist of hexagonal BaGeO 3 at room temperature.…”

Section: Shrinkage and Sintering Behaviourmentioning

confidence: 99%

“…Hexagonal (α)-BaGeO 3 (low-temperature form) has a pseudowollastonite-type structure in which the GeO 4 tetrahedra are linked to 3-membered [Ge 3 O 9 ]-rings [7], whereas orthorhombic (β)-BaGeO 3 (hightemperature form) has a pyroxene-type structure, containing GeO 4 tetrahedra which are linked to 2periodic chains [8]. The phase diagram of the BaO−GeO 2 system was published by Guha [9] and shows the reversible hexagonal orthorhombic transformation at 1200 °C and a melting point at 1280 °C. Moreover, Guha et al [10] observed that the high-temperature form can be retained at room temperature, depending on the cooling rate.…”

Section: Introductionmentioning

confidence: 99%

A barium germanium 1,2-ethanediolato complex as precursor for barium metagermanate

et al. 2007

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The thermal behaviour of [Ba(HOC 2 H 4 OH) 2 Ge(OC 2 H 4 O) 3 ] (2) as a BaGeO 3 precursor, and its phase evolution during thermal decomposition in different atmospheres are described herein.The precursor complex decomposes in air to a finely divided mixture of BaCO 3 and GeO 2 , which subsequently reacts above 650 °C to orthorhombic BaGeO 3 , transforming above 800 °C to hexagonal BaGeO 3 . The shrinkage behaviour of BaGeO 3 compacts made from the as-prepared powders as well as from conventional mixed-oxide powders has been investigated. The samples were characterised by Fourier transformed infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), dilatometric measurements and thermoanalytic investigations (TG/DTA).

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“…Between BaO and BaCeO 3 a eutectic occurs with a composition of ∼46% CeO 2 and a melting point at ∼1440°C. 16 Only one compound, BaNd 2 O 4 , is known in binary BaO−Nd 2 O 3 . 17 In the CeO 2 -Nd 2 O 3 system extensive fluorite Ce 1−X Nd X O ∼2−X/2 solid solubility was reported by several authors.…”

Section: Phase Relations In the Relevant Bao−ceo 2 −Nd 2 O 3 Systemsmentioning

confidence: 99%

Solid Solubility of Neodymium in BaCeO₃

Makovec

Samardžija

Kolář

1997

Journal of the American Ceramic Society

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Incorporation of Nd into the BaCeO3 perovskite structure was studied by quantitative wavelength dispersive spectroscopy‐electron probe microanalysis (WDS/EPMA) in combination with scanning electron microscopy (SEM) and X‐ray powder diffractometry (XRPD). Highly Nd‐doped BaCeO3 specimens, synthesized by mixed oxide technology, were sintered at 1400°C in ambient air. Concentrations of cations obtained by microanalysis were calculated to the ABO3 perovskite formula, considering incorporation of Nd at Ba as well as at Ce sites. Nd‐BaCeO3 solid solutions may be represented by the general formula Ba1−XNdXCe1−YNdYO3−(Y‐X)/2(VO)(Y‐X)/2. The ratio between Nd incorporated at Ba sites and at Ce sites (X/Y) is a function of the starting composition, changing from 1 in the CeO2‐rich part of the BaO‐CeO2‐Nd2O3 system, to ~0.1 in the BaO‐rich part of the system.

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Phase equilibria in the system BaO-GeO2

Cited by 6 publications

References 5 publications

SECOND PHASE (BaGeO[sub 3], BaSiO[sub 3]) NANOCOLUMNS IN YBa[sub 2]Cu[sub 3]O[sub 7−x] FILMS

SECOND PHASE (BaGeO[sub 3], BaSiO[sub 3]) NANOCOLUMNS IN YBa[sub 2]Cu[sub 3]O[sub 7−x] FILMS

A barium germanium 1,2-ethanediolato complex as precursor for barium metagermanate

Solid Solubility of Neodymium in BaCeO₃

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Phase equilibria in the system BaO-GeO2

Cited by 6 publications

References 5 publications

SECOND PHASE (BaGeO[sub 3], BaSiO[sub 3]) NANOCOLUMNS IN YBa[sub 2]Cu[sub 3]O[sub 7−x] FILMS

SECOND PHASE (BaGeO[sub 3], BaSiO[sub 3]) NANOCOLUMNS IN YBa[sub 2]Cu[sub 3]O[sub 7−x] FILMS

A barium germanium 1,2-ethanediolato complex as precursor for barium metagermanate

Solid Solubility of Neodymium in BaCeO3

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Solid Solubility of Neodymium in BaCeO₃