Study of decreased T site-symmetry in the mixed crystals Ag3(PO4,AsO4)

1980 ◽  
Vol 45 (12) ◽  
pp. 3262-3265 ◽  
Author(s):  
Alexander Muck ◽  
Jindřich Čáp ◽  
Bohumil Hájek
Keyword(s):  
Absorption Spectra ◽  
Infrared Absorption ◽  
Factor Group ◽  
Mixed Crystals ◽  
Site Symmetry ◽  
X Ray ◽  
Powder Samples ◽  
Substitution Type ◽  
Infrared Absorption Spectra ◽  
Effective Site

The system Ag3PO4-Ag3AsO4 has been studied by X-ray analysis of the powder samples and infrared absorption spectra. Formation of cubic mixed crystals of the substitution type has been found within the whole concentration range. For the tetrahedral anions at the site T(2) lowering of the site-symmetry to the effective site-symmetry C3 has been found on the basis of the site-and factor-group analyses of the space group Td4.

The infrared absorption spectra of mixed Ag3[AsO4, VO4] crystals

1979 ◽  
Vol 44 (11) ◽  
pp. 3346-3349 ◽  
Author(s):  
Bohumil Hájek ◽  
Alexander Muck ◽  
Olga Smrčková
Keyword(s):  
Absorption Spectra ◽  
Infrared Absorption ◽  
Factor Group ◽  
Mixed Crystals ◽  
Site Symmetry ◽  
Lattice Vibrations ◽  
Space Group ◽  
Infrared Absorption Spectra ◽  
Effective Site

Mixed Ag3[AsO4, VO4] crystals were prepared over the whole concentration range. In the 0-40% mol. Vanadate concentration range the mixed crystals are isostructural with Ag3AsO4 (T4d, Z = 2). Site- and factor group analyses were carried out for this space group and structure. Above 60 mol% vanadate, the mixed crystals are tetragonal with Ag3VO4 structure. It follows from the behaviour of the ν4AsO3-4 vibration that, in cubic mixed crystals with 40 mol% Ag3VO4, the site-symmetry T is reduced to effective site-symmetry C3 by the effect of lattice vibrations of the T(F) and R(F) types.

Infrared absorption spectra of Ag3[PO4, VO4] mixed crystals

1979 ◽  
Vol 44 (3) ◽  
pp. 823-828 ◽  
Author(s):  
Bohumil Hájek ◽  
Alexander Muck ◽  
Olga Smrčková
Keyword(s):  
Mixed Crystal ◽  
Group Analysis ◽  
Factor Group ◽  
Mixed Crystals ◽  
Site Symmetry ◽  
Lattice Vibrations ◽  
Concentration Region ◽  
Site Group ◽  
Infrared Absorption Spectra ◽  
Effective Site

Ag3[PO4, VO4] mixed crystals were prepared in the whole concentration region. For 0-40 mol % vanadate, the mixed crystals are isostructural with the low-temperature modification of Ag3PO4 (Td4, Z = 2); the site group and factor group analysis was performed for this space group. Mixed crystals containing 60% vanadate and more are tetragonal with the structure of Ag3VO4. From the analysis of the infrared spectra it follows that in the cubic mixed crystal with 40 mol % Ag3VO4, the site symmetry T is additionally lowered to the effective site symmetry C3 due to the effect of the lattice vibrations of the types T(F) and R(F).

SYNTHESIS, POTENTIOMETRIC TITRATIONS, AND SPECTRA OF PYRAZOLONES

1953 ◽  
Vol 31 (11) ◽  
pp. 1025-1039 ◽  
Author(s):  
Paul E. Gagnon ◽  
Jean L. Boivin ◽  
René J. Paquin
Keyword(s):  
Absorption Spectra ◽  
Powder Diffraction ◽  
Infrared Absorption ◽  
Dissociation Constants ◽  
Alkyl Halides ◽  
X Ray ◽  
Alkyl Radicals ◽  
Potentiometric Titrations ◽  
Infrared Absorption Spectra ◽  
Diffraction Patterns

Monosubstituted benzoylacetic esters, obtained by condensation of n-alkyl halides with ethyl benzoylacetate, were reacted with hydrazine and phenylhydrazine to give 3-phenyl and 1,3-diphenyl 5-pyrazolones monosubstituted in position 4 by alkyl radicals R (R = H, CnH2n+1(n-1 to 10), and C6H5CH2.). The dissociation constants of the pyrazolones were determined by potentiometric titrations. A study was made of the ultraviolet absorption spectra in both neutral and acid medium and of the infrared absorption spectra. X-ray powder diffraction patterns and data of the pyrazolones were obtained.

Conversion of Monetite, CaHPO4, To Apatites: Effect of Carbonate on the Crystallinity and the Morphology of the Apatite Crystallites

1970 ◽  
Vol 14 ◽  
pp. 57-66 ◽  
Author(s):  
Racquel Z. LeGeros ◽  
John P. LeGeros ◽  
Otto R. Trautz ◽  
W. Paul Shirra
Keyword(s):  
Crystallite Size ◽  
Diffraction Pattern ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Carbonate Content ◽  
Structural Effects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbonate Solutions ◽  
Infrared Absorption Spectra

AbstractThe incorporation of carbonate in the apatite causes a decrease in crystallite size as demonstrated in precipitated apatites prepared at 37°C. Carbonate disturbs the crystallization of the growing apatite crystallites to such an extent that materials with more than 15 wt% CO3 gives an ‘amorphous’ x-ray diffraction pattern. The incorporation of carbonate in precipitates prepared at 100°C. causes a shortening of the a-axis and a lengthening of the c-axis which is proportional to the carbonate content, supporting the concept that in these apatites, CO3 substitutes for PO4 (11). X-ray diffraction linebroadening studies of CO3-apatites precipitated at 100°C and electron micrographs show that the size and shape of the crystallites change from long needles to smaller rods to tiny spheroids, depending upon the amount of CO3. Carbonate causes the bonding in the apatite to become weaker and more isotropic, which results in the small spheroidal crystals.This paper reports the effect of carbonate on lattice parameters and morphology of carbonate-apatites which have been prepared by the conversion of rnonetite, CaHPO4 in hot carbonate solutions. The structural effects of CO3 on the apatite is further reflected by the modification of the vibrations of the PO4 groups in the infrared absorption spectra. The morphology of ‘amorphous’ CO3- containing apatitic precipitates and that of CO3∼apatite with high CO3 content (prepared at 100°C) is similar, i.e., spheroidal in shape, but greatly differing in crystallite size.

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