Habit, dislocation densities, and microhardness of NaClO<sub>3</sub>‐NaBrO<sub>3</sub> mixed crystals

Hussain, Khalid; Subhadra, K. G.; Rao, K. Kishan

doi:10.1002/crat.2170230207

Cited by 8 publications

(5 citation statements)

References 16 publications

(1 reference statement)

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“…It is interesting to note that the present values are higher than the earlier reported values. The present hardness value of 135 kg/mm 2 for NaClO 3 is slightly close to the value of 123 kg/mm 2 of Haussuhl (1964) with a deviation of about 9% whereas the present value of 235 kg/mm 2 of NaBrO 3 is close to Hussain et al (1988) results with a deviation of about 10%. Hence it is necessary to indicate the hardness value from the load independent region only.…”

Section: Load Variation Of Hardnesssupporting

confidence: 75%

“…Although considerable amount of work is reported on physical properties like elastic constants (Bechmann 1951;Radha and Gopal 1967), thermal expansion (Sharma 1950) etc but meagre amount of information is available on hardness, which is an important strength parameter (Haussuhl 1964;Hussain et al 1988). Physically speaking hardness is the resistance offered by the crystal for the movement of dislocations and practically it is the resistance offered by the crystal for localized plastic deformation.…”

Section: Introductionmentioning

confidence: 99%

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Microhardness studies on as-grown faces of NaClO3 and NaBrO3 crystals

2002

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Single crystals of NaClO 3 and NaBrO 3 are grown from their aqueous solutions at a constant temperature of 35°C by slow evaporation by using good quality seed crystals. Systematic microhardness studies are made on as-grown faces of these crystals at various loads. Typical cracks are observed at the corners of the impressions in NaClO 3 whereas in addition to the cracks at the corners microcracks also appeared in NaBrO 3 crystals around the impressions. The impressions formed in NaBrO 3 are not very clear as in NaClO 3 , a possible mechanism for it is discussed. The work hardening index number (n) for both these crystals is around 1⋅ ⋅6 suggesting that these are moderately harder samples. The hardness studies point out that NaBrO 3 is harder than NaClO 3 (∆ ∆H ≈ ≈ 100 kg/mm 2), this could be due to strong inter ionic forces acting between Na-Br in NaBrO 3 crystals. Using Gilman's empirical relation, hardness values are calculated from the values of elastic constants (C 44) and are found to be close to the experimental results.

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Section: Load Variation Of Hardnesssupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Microhardness studies on as-grown faces of NaClO3 and NaBrO3 crystals

2002

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“…However, studies of the chirality of NaCl 1− x Br x O 3 mixed crystals are few. Hussain et al (1988) reported that the morphology of NaCl 1− x Br x O 3 mixed crystals changed from cube to tetrahedron as x increased and anomalous birefringence in NaCl 1− x Br x O 3 mixed crystals was observed indicating that these crystals did not have cubic symmetry. Crundwell et al (1997) reported that the sodium halate mixed crystals existed in triclinic symmetry, while Shtukenberg et al (2004) reported that some crystals existed in monoclinic symmetry when x <0.255.…”

Section: Introductionmentioning

confidence: 99%

Characterization of unidirectionally grown NaCl_1−xBr_xO₃ crystals

Song

Zhang

et al. 2009

Powder Diffr.

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NaCl1−xBrxO3 single crystals were prepared by unidirectional crystallization. The influences of the composition on structure, quality, and optical properties of NaCl1−xBrxO3 crystals were investigated. X-ray powder diffraction analysis revealed that the diffraction patterns for the NaCl1−xBrxO3 crystals have almost the same set of peaks as those of NaClO3 and NaBrO3, except that an extra very weak forbidden (100) diffraction peak was detected at about 13.3° 2θ for crystals grown from solutions of BrO3−∼15–70 at. % (i.e., x=0.15–0.70). These crystals can, therefore, be considered to have a distorted cubic structure closely related to the cubic structures of NaClO3 (x=0) and NaBrO3 (x=1). Our study also found that good-quality crystals can only be obtained in two doping ranges (x>0.75 or x<0.10). Outside these two ranges, the crystals tended to crack and even became opaque. Lattice distortions in the crystals were the probable cause as revealed by X-ray powder diffraction patterns. The optical activity of NaCl1−xBrxO3 crystals measured by a laser was found to decrease from 2.89 to 2.01°/mm with increasing value of x from 0 to 0.02. Stimulated Raman scattering of NaBr0.90Cl0.10O3 crystals was measured using a 0.532-μm ps laser as a pump source and four anti-Stokes lines plus six Stokes lines were observed. The fourth anti-Stokes emission was found to be at 454.5 nm and the sixth Stokes emission at 713.6 nm. Its Raman gain coefficient was determined to be 18.4 cm/Gw.

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“…The hardness was determined at various loads in the range 10-100 g. For each load several indentations were made and the mean value of the hardness was taken. This value is accurate within 72 kg/mm 2 [26]. The load vs. hardness values of undoped and dye doped BGCC single crystals are shown in Fig.…”

Section: Hardness Studiesmentioning

confidence: 93%