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0853957_Boolchand

On the Intermediate Phase in Alkali Borate Glasses Punit Boolchand, University of Cincinnati Main Campus, DMR 0853957.

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0853957_Boolchand

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  1. On the Intermediate Phase in Alkali Borate GlassesPunit Boolchand, University of Cincinnati Main Campus, DMR 0853957 • The present finding of an Intermediate Phase (IP), a rigid and stress-free phase that does not age, in Alkali Borates is of much interest at a basic level1 and for sustainability issues in commercial applications. • Calorimetric experiments on (Na2O)x(B2O3)1-x glasses show2 variation of Tg(x) to reveal a broad maximum near x~30%,(Fig. a), while that of the enthalpy of relaxation at Tg, ΔHnr(x) to show a square-well like variation in the 20% < x < 40% range, the IP (Fig.c). Raman scattering strength of select modes near 770 cm-1,740 cm-1 and 705 cm-1 show maxima near x = 25%, 33% and 37% (Fig b).These are modes of triborate, diborate and tripen-taborates. The former superstructure perco-lates at the onset, while the latter two at the end of IP, yielding insights into aspects of structure. The step-like increase of electrical conductivity (Fig.d), σ(x), near x = 20%, confirms onset of IP to be the stress transition. • . Please insert an image (.JPEG)or group of images here. If you need more space, you may reduce the adjacent textbox. Please use lettering that is clearly visible (i.e. not too small). You could also insert chemical or mathematical formulas, molecular models, etc. Visually appealing images that can be appreciated by non-experts are Variation of (a) Tg(x), (b) Raman mode scattering strength, (c) ΔHnr(x), (d) Electrical conductivity, σ(x), in (Na2O)x(B2O3)1-x glasses as a function of Na2O content x. The step-like increase in σ(x) suggests that onset of IP is the stress transition 3. The IP is shown as the blue shaded column in the 20% < x < 40% range in each panel. • 1. P.Boolchand et al. Phil. Mag. B  85, 3823 (2005), 2. K.Vignarooban, MS Thesis, Univ of Cincinnati(2011). 3. D.Novita et al. Phys. Rev. Lett. 98, 195501 (2007).

  2. On the Intermediate Phase in Alkali Borates Punit Boolchand, University of Cincinnati Main Campus, DMR 0853957 Birefringence measurements on Alkali Borate glasses, using a polarizing microscope, are being performed by Maulik Desai, a Sycamore High School junior working in the lab. of PI, with graduate students, Siddhesh, Kapila and Vigna assisting Maulik. Undergraduates from Northern Kentucky University working with Dr. W J Bresser are visiting the PI on a project dealing with use of Ferrites as pressure sensors. From L to R: Dr. P. Boolchand (PI), James Castle, Vincent Campbell, Mark Fein, Dr. W J Bresser, and Julie Fisher. The PI has also assisted graduate students of several colleagues at UC with their research projects.

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