Growth and characterization of gel grown calcium pyrophosphate tetrahydrate crystals

Parekh, B. B.; Joshi, Mayank

doi:10.1002/crat.200610784

Cited by 25 publications

(10 citation statements)

References 21 publications

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“…As the frequency increases, a point will be reached where the space charge cannot sustain and comply with the variation of external field and hence the polarization decreases, which gives rise to diminishing values of dielectric constant. However, the nature of variation of dielectric constant with frequency of applied field suggests comparatively very less changes in the low frequency region unlike in calcium pyrophosphate tetrahydrate crystals [27]. The dielectric constant values of Fe−Mn−Co levo-tartrate crystals are comparatively less responsive to the variation of frequency of applied field in the range studied.…”

Section: 4h 2 Omentioning

confidence: 76%

Characterization of gel grown iron‐manganese‐cobalt ternary levo‐tartrate crystals

Joshi¹,

Tank

Parekh

et al. 2010

Cryst. Res. Technol.

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In the present investigation, iron-manganese-cobalt ternary levo-tartrate crystals of different compositions have been grown by single-diffusion gel growth technique in silica hydrogel medium. The metallic composition in the crystals was estimated by EDAX. The coloration of the crystals changed with composition of metallic content. The powder XRD study suggested the crystalline nature and indicated the presence of some extra phases. The grown crystals were characterized by FT-IR spectroscopy, TGA, dielectric and Vibrating Sample Magnetometer (VSM) studies. The FT-IR study suggested the presence of O-H, C=O, C-O and metal-oxygen bonds. The effect of composition of metallic content was observed in certain absorption regions in FT-IR spectra. The thermal stability of the crystals was studied by thermogravimetry and the kinetic and thermodynamic parameters of dehydration were calculated. The effect of composition of ternary levo-tartrate was observed in dielectric study. The dielectric study was carried out in the frequency range of applied field from 500 Hz to 1 MHz. The variations in dielectric constant, dielectric loss, a.c. resistivity and a.c. conductivity with frequency of applied field were studied. VSM study suggested that all crystals were of paramagnetic nature.

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Section: 4h 2 Omentioning

confidence: 76%

Characterization of gel grown iron‐manganese‐cobalt ternary levo‐tartrate crystals

Joshi¹,

Tank

Parekh

et al. 2010

Cryst. Res. Technol.

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“…The authors have applied the Coats and Redfern relation (Coats and Redfern 1964) to evaluate the kinetic parameters for dehydration process from the thermogram. The Coats and Redfern relation is as follows, which has been discussed in detail elsewhere (Parekh and Joshi 2007) …”

Section: Resultsmentioning

confidence: 99%

“…The values of activation energy and frequency factors were calculated from the plot, which are given in table 2. Thermodynamic parameters were also calculated using standard formulae reported elsewhere (Parekh and Joshi 2007). Table 2 shows the values of these parameters.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, the variation of dielectric constant, dielectric loss and a.c. conductivity with frequency of applied field was reported (Parekh and Joshi 2007) for calcium pyrophosphate tetrahydrate crystals. The variation of dielectric loss, tan δ, with applied field is shown in figure 6, which suggests that the dielectric loss decreases as the frequency increases.…”

Section: Resultsmentioning

confidence: 99%

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Thermal, FT-IR and dielectric studies of gel grown sodium oxalate single crystals

et al. 2008

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Oxalic acid metabolism is important in humans, animals and plants. The effect of oxalic acid sodium salt is widely studied in living body. The growth of sodium oxalate single crystals by gel growth is reported, which can be used to mimic the growth of crystals in vivo. The grown single crystals are colourless, transparent and prismatic. The crystals have been characterized by thermogravimetric analysis, FT-IR spectroscopy and dielectric response at various frequencies of applied field. The crystals become anhydrous at 129⋅3°C. Coats and Redfern relation is applied to evaluate the kinetic and thermodynamic parameters of dehydration. The dielectric study suggests very less variation of dielectric constant with frequency of applied field in the range of 1 kHz-1 MHz. The nature of variation of imaginary part of complex permittivity, dielectric loss and a.c. resistivity with applied frequency has been reported.

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“…The resonance observed at 723 cm -1 is attributed to symmetric P-O-P bridge vibration, while the resonance centered at *550 cm -1 can be attributed to O-P-O bonding. The absorptions between 400 and 520 cm -1 are due to the presences of oxygen-calcium bonds [20]. Taken together, the FTIR spectrum showed that the product formed in 1.0 M K 2 HPO 4 solution at pH = 7.0 contained the (P 2 O 7 ) 2-, (HP 2 O 7 ) 3-, and (PO 4 ) 3-groups, indicating the presence of a pyrophosphate, as well as a phosphate material.…”

Section: Composition and Phase Analysis Of Reacted 45s5c Microspheresmentioning

confidence: 99%

Long-term conversion of 45S5 bioactive glass–ceramic microspheres in aqueous phosphate solution

Rahaman

Day

et al. 2012

J Mater Sci: Mater Med

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The conversion of 45S5 glass and glass-ceramics to a hydroxyapatite (HA)-like material in vitro has been studied extensively, but only for short reaction times (typically <3 months). In this paper, we report for the first time on the long-term conversion of 45S5 glass-ceramic microspheres (designated 45S5c) in an aqueous phosphate solution. Microspheres of 45S5c (75-150 μm) were immersed for 10 years at room temperature (~25 °C) in K(2)HPO(4) solution with a concentration of 0.01 M or 1.0 M, and with a starting pH of 7.0 or 9.5. The reacted 45S5c microspheres and solutions were analyzed using structural and analytical techniques. Only 25-45 vol% of the 45S5c microspheres were converted to an HA-like material after the 10 year reaction. In solutions with a starting pH of 9.5, an increase in the K(2)HPO(4) concentration from 0.01 to 1.0 M resulted in a doubling of the volume of the microspheres converted to an HA-like material but had little effect on the composition of the HA-like product. In comparison, reaction of the 45S5c microspheres in the solution with a starting pH of 7.0 resulted in an HA-like product in the 0.01 M K(2)HPO(4) solution but a calcium pyrophosphate product, Ca(10)K(4)(P(2)O(7))(6).9H(2)O, in the 1.0 M solution. The consequences of these results for the long-term use of 45S5 glass-ceramics in biomedical applications are discussed.

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Growth and characterization of gel grown calcium pyrophosphate tetrahydrate crystals

Cited by 25 publications

References 21 publications

Characterization of gel grown iron‐manganese‐cobalt ternary levo‐tartrate crystals

Characterization of gel grown iron‐manganese‐cobalt ternary levo‐tartrate crystals

Thermal, FT-IR and dielectric studies of gel grown sodium oxalate single crystals

Long-term conversion of 45S5 bioactive glass–ceramic microspheres in aqueous phosphate solution

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