Showing papers by "P. N. Kotru published in 1994"
TL;DR: The results of microhardness measurements on (100) and (110) planes of flux-grown LaBO3 crystals, in the applied load range of 10-100g, are presented in this article.
Abstract: Results of microhardness measurements on (100) and (110) planes of flux-grown LaBO3 crystals, in the applied load range of 10–100g, are presented. The microhardness was found to decrease with increasing load in a non-linear manner. By applying Hays and Kendall's law, the materials resistance pressure and other constants of the equation could be calculated. Hardness anisotropy, showing periodic variation of H
v with the maxima and minima repeating at every 15° change in orientation of the indentor, is described and discussed. H
max/Hmin are estimated as 1.14 and 1.06 for (100) and (110) planes, respectively. The fracture toughness values, K
c, determined from measurements of crack lengths, are estimated to be 1.6, 1.7 MN m−3/2 (for (100) planes) and 1.2, 1.5 MN m−3/2 (for (110) planes) at 90 and 100g loads, respectively. The brittleness index, B
i, is estimated as 4.6, 4.0 μm−1/2 (for (100) planes) 6.0, 4.6 μm−1/2 (for (110) planes) at 90 and 100g, loads respectively.
35 citations
TL;DR: In this paper, the growth of neodymium heptamolybdate crystals is described in the system Nd(NO3)3-MoO3-NH4OH-HNO3- Na2SiO3 using a single gel, single tube technique.
Abstract: The growth of neodymium heptamolybdate crystals is described in the system Nd(NO3)3-MoO3-NH4OH-HNO3- Na2SiO3 using a single gel, single tube technique. The influence of pH, gel concentration and concentration of upper and lower reactants on the size, quality and nucleation density of the crystals is discussed. The techniques of concentration programming and seeded growth are used to enhance the crystal size. Factors influencing the formation of Liesegang rings during the growth are described. Both gel pH and temperature are observed to have a remarkable effect on Liesegang ring formation. The grown crystals are observed to exhibit varied morphology, for example platelets, cuboids, spherulites, crystal aggregates and coalesced crystals.
10 citations
TL;DR: In this paper, the results of Vickers microhardness measurements carried out on (110 and (001) planes of flux-grown ErFeO3 single crystals are presented.
9 citations
TL;DR: In this article, the results of energy-dispersive X-ray analysis, Xray and electron diffraction, infrared spectroscopy, and optical and scanning electron microscopy are reported.
9 citations
TL;DR: In this paper, the growth of single crystals of lanthanum heptamolybdate is achieved by allowing controlled diffusion of La ions through silica gel using the system La(NO 3 ) 3 -MoO 3 -NH 4 OH-HNO 3 -Na 2 SiO 3.
Abstract: The growth of single crystals of lanthanum heptamolybdate is achieved by allowing controlled diffusion of La ions through silica gel using the system La(NO 3 ) 3 -MoO 3 -NH 4 OH-HNO 3 -Na 2 SiO 3 . The reaction mechanism leading to the growth is reported. Mechanism of crystallization of La heptamolybdate is discussed. Formation of Liesegang rings consisting of La heptamolybdate crystals in the system is reported. It is observed that concentration programming and seeded growth enhances the size of crystals. The crystals grown in the system are single crystal platelets exhibiting squarish or octagonal facets. Some crystals exhibit a spherulitic morphology
9 citations
TL;DR: The results were obtained from X-Ray powder diffractograms, infrared spectra, and quantitative chemical analysis of gel-grown pure and mixed crystals of yttrium and samarium tartrates as mentioned in this paper.
4 citations
TL;DR: In this article, it is shown that the variation in the concentration of gallium and indium in the substituted hexaferrites affects the cleavage in these crystals, and the suitability of substituted crystals as substrates for the growth of good-quality hexaferrite films is discussed.
3 citations