Vegard's Rule Revisited in BaxPb1−x(NO3)2 by NMR and XRD

Crundwell, Guy; Cowans, Brett A.; Hopkins, Jeffrey A.; Grutzner, John B.; Kahr, Bart

doi:10.1006/jssc.1999.8288

Cited by 18 publications

(24 citation statements)

References 20 publications

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“…Data collected from the {001} growth sector of a series of mixed crystals indicate a linear correlation between the unitcell parameters and the concentration of selenate in the crystal, obeying Vegard's rule (Crundwell et al, 1999;Gopalan & Kahr, 1993). At 100 K, the unit-cell parameters of EDS are a = 5.9762 (4) Å and c = 17.986 (2) Å , while those of EDSe are a = 6.1155 (4) Å and c = 18.132 (1) Å .…”

Section: Resultsmentioning

confidence: 90%

Tuning the optical isotropic point of mixed crystals of ethylenediammonium sulfate/selenate

et al. 2020

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In anisotropic crystals, optical isotropic points are wavelengths where linear birefringence disappears because the refractive indices for both eigenmodes are accidentally equivalent. Here, the optical isotropic point of ethylenediammonium selenate (EDSe) is tuned by generating a solid-solution series of EDSe doped with sulfate. Mueller matrix polarimetry and single-crystal X-ray diffraction are used to correlate changes in linear birefringence with the crystal composition of EDS x Se 1Àx . A scheme for using mixed crystals with isotropic points as tunable birefringent optical bandpass filters is proposed and their performance is modeled. research papers J. Appl. Cryst. (2020). 53, 51-57 Melissa Tan et al. Tuning the optical isotropic point of mixed crystals 57

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Section: Resultsmentioning

confidence: 90%

Tuning the optical isotropic point of mixed crystals of ethylenediammonium sulfate/selenate

et al. 2020

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“…Crystals of Ba and Pb nitrates (space group P 2 1 3 (Maiwa et al, 1998) and, correspondingly, point group (H-M symbol) 23) have faces of positive and negative tetrahedrons and cubes (Groth, 1908) and, sometimes, of rhombododecahedrons. In a stoichiometric solution, Ba nitrate crystallized as transparent crystals with rare inclusions, whereas Pb nitrate formed milk white crystals with tiny solution inclusions (Crundwell et al, 1999). Inclusions in Pb nitrate crystals are thought to form via the adsorption of hydrolysis products on the crystal surface (Sal'nikova and Treivus, 1973).…”

Section: Resultsmentioning

confidence: 99%

“…Compositions were also calculated for a number of randomly selected single crystals with Ba(NO 3 ) 2 concentrations from 35 to 100 mol % from their indices of refraction (measured by the immersion method) (Tatarsky, 1965). Thereby, we proceeded from the assumption that the indices of refraction of the crystals are linearly dependent on their composition, analogously to the linear composition dependence of the unit cell parameters known for this series (Crundwell et al, 1999). The errors were within 0.002, i.e., did not exceed 2 mol %.…”

Section: Methodsmentioning

confidence: 99%

Cocrystallization of isomorphic components in solutions and crystal zoning: An example of the (Ba,Pb)(NO3)2 series

et al. 2007

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The phase equilibrium and growth of mixed (Ba,Pb)(NO 3 ) 2 crystals in aqueous solutions were investigated. The microcrystallization method was adapted to systems with isomorphic components, where crystal composition deviates from the thermodynamic equilibrium even at a low supercooling. The solid phase is characterized by continuous miscibility of the components within the analyzed ranges of temperature and solution composition. The diagram is characterized by substantial nonlinearity of the solubility isotherms and nonuniformity of the solid isocomposite location. Quasiequilibrium paths change their slope depending on solution enrichment in Ba(NO 3 ) 2 and depletion in Pb(NO 3 ) 2 . The area of curvature of quasiequilibrium paths is coordinated with the area of the changing isotherm slope, i.e., the area of "remarkable" points, where the behavior of the system changes drastically. Examples of theoretical zoning of a crystal approximated to a sphere were calculated for paths at a temperature decreasing from 50 to 15 ° C. The content of the Ba component decreases toward the periphery with the consecutive overgrowing of zones. Each zone corresponds to one gram of (Ba,Pb)(NO 3 ) 2 . Crystals grown from different initial solutions consist of different numbers of zones owing to the nonlinearity of solubility isotherms. Specific features of mixed crystal formation should be taken into account in genetic interpretation of natural minerals of mixed composition.

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“…Chemical shifts of ±100 ppm from that of Pb(NO 3 ) 2 have been reported when Ba is substituted for Pb. [22,23,26] Here we describe NMR spectroscopic results for synthetic mixed Ca/Pb apatites along the series HAp-HPm. We obtain wellresolved 207 Pb SP/MAS NMR spectra for the HPm endmember using standard solid-state NMR techniques, but unfavorable 207 Pb relaxation properties inhibit application of 207 Pb{ 1 H} crosspolarization (CP) MAS NMR.…”

Section: Introductionmentioning

confidence: 99%

Solid‐state NMR spectroscopy of Pb‐rich apatite

Mason

Hirner

et al. 2009

Magnetic Reson in Chemistry

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Pb-containing hydroxylapatite phases synthesized under aqueous conditions were investigated by X-ray diffraction and solid-state nuclear magnetic resonance (NMR) techniques to determine the Pb, Ca distribution. 31P and 1H magic-angle spinning (MAS) NMR results indicate slight shifts of the isotropic chemical shift with increased Ca content and complex lineshapes at compositions with near equal amounts of Ca and Pb. 31P{207Pb} and 1H{207Pb} rotational-echo double resonance (REDOR) results for intermediate compositions show that resolved spectral features cannot be assigned simply in terms of local Ca, Pb configurations or coexisting phases. 207Pb MAS NMR spectra are easily obtained for these materials and contain well-resolved resonances for crystallographically unique A1 and A2 Pb sites. Splitting of the A1 and A2 207Pb resonances for pure hydroxyl-pyromorphite (Pb10(PO4)6(OH)2) compared to natural pyromorphite (Pb5(PO4)3Cl) suggests symmetry reduced from hexagonal. We find that 207Pb{1H} CP/MAS NMR is impractical in Pb-rich hydroxylapatites due to fast 207Pb relaxation.

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Vegard's Rule Revisited in BaxPb1−x(NO3)2 by NMR and XRD

Cited by 18 publications

References 20 publications

Tuning the optical isotropic point of mixed crystals of ethylenediammonium sulfate/selenate

Tuning the optical isotropic point of mixed crystals of ethylenediammonium sulfate/selenate

Cocrystallization of isomorphic components in solutions and crystal zoning: An example of the (Ba,Pb)(NO3)2 series

Solid‐state NMR spectroscopy of Pb‐rich apatite

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