Ionic transport and structure in high pressure Na2O:GeO2 glasses

Secco, Richard A.; Ault, Katherine M.

doi:10.1016/s0022-3093(98)00692-9

Cited by 11 publications

(5 citation statements)

References 29 publications

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“…It has been reported that Ge 4+ cations like to segregate along the grain boundary, resulting in the reduction of the jump of mobile ions. As reported by Secco et al [10], a lower ionic hopping frequency is obtained which in turn caused the decrease in conductivity of the ceramics.…”

Section: Introductionsupporting

confidence: 59%

Effects of GeO2 addition on physical and electrical properties of BaFe0.5Nb0.5O3 ceramic

Kantha¹,

Pisitpipathsin²,

Pengpat³

et al. 2012

Materials Research Bulletin

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Section: Introductionsupporting

confidence: 59%

Effects of GeO2 addition on physical and electrical properties of BaFe0.5Nb0.5O3 ceramic

Kantha¹,

Pisitpipathsin²,

Pengpat³

et al. 2012

Materials Research Bulletin

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“…Measurements on Sc 2 ͑WO 4 ͒ 3 at 400°C showed an initial decrease in ionic conductivity with increasing pressure followed by an increase above 2.9 GPa. [60][61][62] This change in the pressure dependence of conductivity was coincident with the pressure-induced amorphization of the material, as seen by synchrotron energy dispersive x-ray diffraction ͑EDXRD͒ on samples in a multianvil apparatus at 400°C. In a room temperature Raman spectroscopy and EDXRD study of Sc 2 ͑MoO 4 ͒ 3 , using diamond anvil cells ͑DACs͒ with methanol-ethanol or methanol-ethanol-water as pressure transmitting media, reversible phase transitions were observed at 0.3 GPa and 2.7 GPa followed by the onset of amorphization at about 3.7 GPa.…”

Section: Introductionmentioning

confidence: 62%

“…[38][39][40][41][42][60][61][62][63][64] Samples of Sc 2 W 3 O 12 recovered from room temperature and high pressure using a large volume press were examined by diffraction, and an irreversible pressure-induced amorphization was observed to start at ϳ5 GPa and to be complete by ϳ8 GPa. 38 No intermediate pressure phase transformations were reported.…”

Section: Introductionmentioning

confidence: 99%

In situhigh-pressure synchrotron x-ray diffraction study ofSc2W3O12at up to 10 GPa

et al. 2005

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Sc 2 W 3 O 12 is known to display both negative thermal expansion and significant Sc 3+ conductivity. Monochromatic synchrotron x-ray powder diffraction was used to study Sc 2 ͑WO 4 ͒ 3 at pressures up to 10 GPa in diamond anvil cells. Nitrogen and isopropanol were both used as pressure transmitting media. A phase transition from orthorhombic ͑Pnca͒ to monoclinic ͑P2 1 / a͒ symmetry was observed at ϳ0.3 GPa with a volume reduction of ϳ1.7%. A second crystalline to crystalline phase transition was seen at ϳ2.8 GPa. The latter was not reversible on decompression. The orthorhombic phase displays highly anisotropic compressibility, but that of the monoclinic phase is almost isotropic ͓orthorhombic in isopropanol ␤ a = 6.32͑16͒ ϫ 10 −3 GPa −1 , ␤ b = 1.76͑21͒ ϫ 10 −2 GPa −1 , ␤ c = 6.84͑32͒ ϫ 10 −3 GPa −1 ; monoclinic in isopropanol ␤ a = 1.85͑3͒ ϫ 10 −2 GPa −1 , ␤ b = 1.78͑3͒ ϫ 10 −2 GPa −1 , ␤ c = 1.69͑9͒ ϫ 10 −2 GPa −1 ͔. Sc 2 ͑WO 4 ͒ 3 is very soft even when compared to most other NTE phases. Fitting a Birch-Murnaghan equation of state to data from the experiment in isopropanol gave a bulk modulus ͑K 0 ͒ of 31͑3͒ for the orthorhombic and 14͑1͒ GPa for the monoclinic phase. This reduction in bulk modulus at the phase transition and the reduction in volume per formula unit is almost entirely associated with changes in the orthorhombic a and c directions. The variation of b ortho and its monoclinic equivalent lattice constant is essentially continuous through the transition. The pressure of the orthorhombic to monoclinic phase transition in A 2 M 3 O 12 compounds does not have a strong dependence on the identity of the A 3+ cation. Amorphization did not occur in the pressure range studied.

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“…To date, there have been high pressure studies on the following members of the A 2 M 3 O [25][26][27][28][29][30][31][32][33][34][35][36]. For Sc 2 Mo 3 O 12 , crystalline to crystalline phase transitions have been reported at 0.3 and 2.7 GPa followed by PIA at ∼3.7 GPa on the basis of room temperature Raman and energy dispersive x-ray diffraction (EDXRD) data [31].…”

Section: Introductionmentioning

confidence: 99%

High pressure synchrotron x-ray powder diffraction study of Sc₂Mo₃O₁₂and Al₂W₃O₁₂

Varga

Wilkinson

Lind

et al. 2005

J. Phys.: Condens. Matter

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Synchrotron x-ray powder diffraction was used to study Sc 2 Mo 3 O 12 and Al 2 W 3 O 12 at high pressure in a DAC. Both compounds adopt the orthorhombic Sc 2 W 3 O 12 structure under ambient conditions and exhibit anisotropic negative thermal expansion. A phase transition from orthorhombic (Pnca) to monoclinic (P2 1 /a) symmetry was observed at ∼0.25 GPa for Sc 2 Mo 3 O 12 and at ∼0.1 GPa for Al 2 W 3 O 12 associated with a volume reduction of ∼1.5-2%. A second crystalline to crystalline phase transition was clearly seen only for Sc 2 Mo 3 O 12 (2.5-3.0 GPa). Peak broadening and almost complete amorphization were observed for Sc 2 Mo 3 O 12 at ∼8 GPa, and this was not fully reversible on decompression. At 7 GPa, the amorphization of Al 2 W 3 O 12 was not as advanced as for the molybdate and on decompression crystalline material was recovered. The compressibility of orthorhombic Sc 2 Mo 3 O 12 is highly anisotropic, but it is almost isotropic for both monoclinic Sc 2 Mo 3 O 12 and Al 2 W 3 O 12 . Both compounds show a reduction in their bulk moduli (K 0 ) at the orthorhombic to monoclinic transition: 32(2) GPa for orthorhombic and 16(1) GPa for monoclinic Sc 2 Mo 3 O 12 , and 48 GPa for orthorhombic and 28(1) GPa for monoclinic Al 2 W 3 O 12 . Sc 2 Mo 3 O 12 displays very similar high pressure behaviour to the previously studied Sc 2 W 3 O 12 .

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Ionic transport and structure in high pressure Na2O:GeO2 glasses

Cited by 11 publications

References 29 publications

Effects of GeO2 addition on physical and electrical properties of BaFe0.5Nb0.5O3 ceramic

Effects of GeO2 addition on physical and electrical properties of BaFe0.5Nb0.5O3 ceramic

In situhigh-pressure synchrotron x-ray diffraction study ofSc2W3O12at up to 10 GPa

High pressure synchrotron x-ray powder diffraction study of Sc₂Mo₃O₁₂and Al₂W₃O₁₂

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Ionic transport and structure in high pressure Na2O:GeO2 glasses

Cited by 11 publications

References 29 publications

Effects of GeO2 addition on physical and electrical properties of BaFe0.5Nb0.5O3 ceramic

Effects of GeO2 addition on physical and electrical properties of BaFe0.5Nb0.5O3 ceramic

In situhigh-pressure synchrotron x-ray diffraction study ofSc2W3O12at up to 10 GPa

High pressure synchrotron x-ray powder diffraction study of Sc2Mo3O12and Al2W3O12

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High pressure synchrotron x-ray powder diffraction study of Sc₂Mo₃O₁₂and Al₂W₃O₁₂