Microhardness investigations on gel‐grown barium cadmium oxalate mixed crystals

Prakash, Shree; Rao, P. Mohan

doi:10.1002/crat.2170220816

Cited by 7 publications

(3 citation statements)

References 7 publications

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“…The well‐defined role of plasticity in Mohs hardness, besides the original study of Tabor, has been debated even in the last few years . Recently, both experimentally and theoretically, it has been shown that dislocation plasticity accompanies or precedes fracture of ceramic and mineralogic materials. Room‐temperature dislocation microplasticity has been shown from indentations into Al 2 O 3, MoSi 2, 6HSiC, and MgO .…”

Section: Introductionmentioning

confidence: 99%

Toward Demystifying the Mohs Hardness Scale

et al. 2015

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Today, the Mohs scale is used profusely throughout educational systems without any persuasive understanding of the fundamental principles. Why one mineral has a scratch hardness over the next culminating in a scale of 1 (chalk) to 10 (diamond) has no atomistic or structure‐sensitive basis that explains this outcome. With modern computationally based atomistic and multiscale models, there is increasing promise of defining the pressure and rate‐dependent parameters that will allow a fundamental understanding of the Mohs scale. This study principally addresses the combined fracture and plasticity parameters that qualitatively affect fracture at the nanoscale. A physical model wherein the crack tip under a scratch is shielded by dislocations is supported by molecular dynamics (MD) simulations in both ductile aluminum and brittle silicon carbide. Next, this model is applied to nanoindentation data from the literature to produce a ranking of Mohs minerals based on their fundamental properties. As such, what is presented here is a first step to address the flow and fracture parameters ultimately required to provide a figure of merit for scratch hardness and thus the Mohs scale.

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Section: Introductionmentioning

confidence: 99%

Toward Demystifying the Mohs Hardness Scale

et al. 2015

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“…In the present investigations, the main objective of the work is to report growth, characterization, mechanical and dielectric behavior of pure and cadmium (Cd) mixed magnesium hydrogen phosphate crystals. Growth of mixed crystals is interesting because their characteristics change from those of the crystals of single components grown separately, e.g., mixed crystals are found to be harder than pure ones [23,24]. Cadmium (Cd 2+ ) ion which is transition metal has been selected for the modified magnesium hydrogen phosphate because its ionic radius (0.97Ǻ) is very close to that of magnesium (0.65Ǻ) ion.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Behavior Of Mixed Cadmium Magnesium Hydrogen Phosphate Crystal

Bamzai¹,

Gupta²,

Suri³

et al. 2014

Adv. Mater. Lett.

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Magnesium hydrogen phosphate (MHP) and transition metal doped cadmium magnesium hydrogen phosphate (CdMHP) was synthesized in the form of crystalline material by room temperature solution technique known as gel encapsulation technique. The synthesized crystals were then characterized for their structural, mechanical and electrical investigations using various chemical and physical methods. X -ray diffraction analysis (XRD) establishes magnesium hydrogen phosphate and cadmium magnesium hydrogen phosphate belonging to orthorhombic crystal system with space group Pbca. The mechanical behaviour of these crystals was studied by calculating Vicker's hardness number. The behaviour of microhardness with applied load was observed to be complex. The electrical behaviour was carried out by calculating dielectric constant at different temperatures and for different frequencies. The dielectric constant (ε / ) was found to be strongly dependent on temperature and frequency. The transition metal doping of cadmium in magnesium hydrogen phosphate remarkably decrease the value of dielectric constant from 68 to 23. The transition temperature also decreases from 330˚C in case of magnesium hydrogen phosphate to 310˚C in case of cadmium magnesium hydrogen phosphate.

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“…Growth of mixed crystals is interesting because their characteristics change from those of the crystals of single components grown separately. For example, mixed crystals are found to be harder than pure ones (Dharma Prakash and Rao 1987;Kotru et al 1989a). Large variations in the hardness of pure and mixed KBr and KI system are reported (Subba Babu 1978, 1980).…”

Section: Introductionmentioning

confidence: 99%

Crystallization of mixed rare earth (didymium) molybdates in silica gel

et al. 2001

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Experiments on the growth of mixed rare earth (didymium-a combination of La, Nd, Pr and Sm) molybdates in silica gel medium are reported. The optimum conditions conducive for the growth of these crystals are described and discussed. Concentration programming is reported to enhance the size of crystals by twofold ; the maximum size obtained being about 1 mm 3. EDAX results suggest the crystals to be heptamolybdates of type R 2 Mo 7 O 24 , bearing composition La 1⋅ ⋅23 Nd 0⋅ ⋅43 Pr 0⋅ ⋅29 Sm 0⋅ ⋅05 Mo 7 O 24. The didymium molybdate crystals assume morphologies corresponding to those of spherulites, platelets, cuboids and coalesced crystals. Twinned structure in didymium molybdate crystals are also reported. It is explained that spherulitic morphologies result from aggregates of crystals joining in a spherical envelope. It is suggested that the crystals of didymium molybdates grow by two-dimensional spreading and piling up of layers.

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Microhardness investigations on gel‐grown barium cadmium oxalate mixed crystals

Cited by 7 publications

References 7 publications

Toward Demystifying the Mohs Hardness Scale

Toward Demystifying the Mohs Hardness Scale

Dielectric Behavior Of Mixed Cadmium Magnesium Hydrogen Phosphate Crystal

Crystallization of mixed rare earth (didymium) molybdates in silica gel

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