• J H MARKNA

Articles written in Bulletin of Materials Science

• Investigations on structural disorder-induced modifications in the transport behaviour of rare-earth manganites

The results of the studies on structural disorder-induced modifications in the transport behaviour of La$_{0.5}$Pr$_{0.2}$Ca$_{0.3−x}$Ba$_x$MnO$_3$ (LPCBMO) ($0.05 ≤ x ≤ 0.30$) manganites were reported. Structural studies using X-ray diffraction (XRD) measurements confirmed the single phasic nature of all the samples without any detectable impurities. The A-site size disorder ($σ_2$ A) increased from $3.81 \times 10^{−5} (x = 0.05)$ to $14.9 \times 10−5 (x = 0.30)$. With the increase in structural disorder in LPCBMO system, the transport improved for the range: $0.15 ≤ x ≤ 0.30$, which can be ascribed to the enhancement in one electron bandwidth which dominates over the structural disorder effect, while for lower values of $x$, strong competition existed between size disorder and one electron bandwidth. Below 50 K, all $\rho–T$ plots showed resistivity minimum behaviour, which modified with disorder. This behaviour wasdiscussed in detail on the basis of electron–electron interaction having the form: $\rho = [1/(\rho_0 + BT^{1/2})] + \rho_nT_n$. Variation in temperature sensitivity with disorder was also discussed in context of granular morphology and phasesegregation scenario.

• Biohybrid photoelectrodes for solar photovoltaic applications

The biohybrid photoelectrodes have been studied for photovoltaic applications. The hybrid solar cells were prepared using natural dyes and sputtered zinc oxide (ZnO) thin films on fluorine-doped tin oxide substrate. The natural dyes were extracted from basil (tulsi) leaves, spinach, thor (chhitar thor opuntia or prickly pear), pomegranate and sunflower. The dye-modified photoelectrodes expands the light absorbance of the solar spectrum. They have shown an enhancement in photocurrent and photovoltage under illumination relative to the unmodified photoelectrodes. The photovoltage and photocurrent of hybrid cells were measured to test the devices under light in active area of 1${\times}$1 cm$^2$. The hybrid solar cells have achieved solar energy conversion efficiency from 0.01 to 0.1%. Hybrid solar cells may lead to inexpensive and environment friendly solar energy conversion applications, such as solar electricity and solar fuels.

• Bulletin of Materials Science

Volume 46, 2023
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Continuous Article Publishing mode

• Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020