• C B PALAN

Articles written in Bulletin of Materials Science

• Synthesis and luminescence properties of Tb$^{3+}-doped LiMgPO$_4$phosphor Polycrystalline sample LiMg$_{(1.x)}$PO$_4$:$x$Tb$^{3+}$($x = 0.001, 0.002, 0.005, 0.01, 0.02$) phosphor was synthesized via modified solid state method (MSSM). The prepared sample was characterized through XRD pattern (X-ray diffraction) and SEM (scanning electron microscope). Additionally, photoluminescence (PL), optically stimulated luminescence (OSL), thermoluminescence (TL) and other dosimetric properties including dose linearity, reusability and fading were studied. In OSL mode, sensitivity of prepared phosphor was found to be 2.7 times that of LiMgPO$_4$:Tb$^{3+}, B (BARC) phosphor and 4.3 times that of $\alpha$-Al$_2$O$_3$:C (BARC) phosphor. The TL glow consists of overlapping peaks in temperature range of 50-400$^{\circ}$C and first peak (P$_1$) was observed at 150$^{\circ}$C, second peak (P$_2$) at 238$^{\circ}$C, third peak (P$_3$) at 291$^{\circ}$C and fourth peak (P$_4$) at 356$^{\circ}$C. The TL sensitivity of second peak (P$_2$) of LiMgPO$_4$:Tb$^{3+}$ phosphor was compared with $\alpha$-Al$_2$O$_3$:C (BARC) phosphor and found to be 100 times that of the $\alpha$-Al$_2$O$_3$:C (BARC) phosphor. The minimum detectable dose (MDD) was found to be 5.6 $\mu$Gy. Moreover, photoionization cross-sections, linearity, reusability, fading and kinetic parameters were calculated. Also, photoluminescence spectra of LiMgPO$_4$:Tb$^{3+}$ shows characteristic green.yellow emission exciting at 224nm UV source.

• Luminescence properties of terbium-doped Li$_3$PO$_4$ phosphor for radiation dosimetry

A polycrystalline sample of Li$_3$PO$_4$:Tb$^{3+}$ phosphor was successfully synthesized using solid-state diffusion method. This synthesis method is of low cost, low temperature and does not require any other atmospheres for the synthesis. The powder X-ray diffraction (PXRD), photoluminescence (PL) emission and excitation spectra, thermoluminescence (TL) and optically stimulated luminescence (OSL) were measured. The particle size was calculated using the Debye Scherrer formula and found to be 79.42 nm. PL emission spectra of Li$_3$PO$_4$:Tb$^{3+}$ phosphor show the strong prominent peak at 544 nm corresponding to ${}^{5}$D$_4$ to ${}^{7}$F$_5$ transitions of Tb$^{3+}$. The OSL sensitivity of prepared Li$_3$PO$_4$:Tb$^{3+}$ phosphor was 50% of that of $\alpha$-Al$_2$O$_3$:C. Its decay curve consists of three components withphotoionization cross-sections $0.44\times 10^{−17}$, $3.09\times 10^{−17}$ and $23\times 10^{−17}$ cm$^{2}$. The TL glow curve of the prepared sampleconsists of two characteristic peaks, which were deconvoluted using the peak fit software, and kinetic parameters were determined using the peak shape method. TL intensity was compared with that of the commercially availableTLD-500 phosphor. OSL dose response was linear in the measured range and the minimum detectable dose (MDD) was found to be 67.42 $\mu$Gy, while fading of the OSL signal was found to be about 27% in 4200 min after which theOSL signal stabilizes.

• Microwave-assisted synthesis and photoluminescence properties of ZnS:Pb$^{2+}$ nanophosphor for solid-state lighting

Nanocrystalline ZnS:Pb$^{2+}$ phosphor was synthesized by microwave-assisted co-precipitation method. Thephase purity and surface morphology of prepared material were investigated using an X-ray diffractometer (XRD) anda scanning electron microscope. The photoluminescence property was studied by near-UV (nUV) excitation. The XRDpattern of prepared phosphor matches well with that of an ICDD (International Center for Diffraction Data) file. Surfacemorphology of prepared phosphor was found to be in submicron range. As-prepared ZnS:Pb$^{2+}$ phosphor shows a greenemission under nUV excitation. As Pb$^{2+}$ ions are located on a regular Zn$^{2+}$ site they produce a green emission band inthe range of 400–650 nm, centred at 500 nm, under excitation wavelength of 357 nm, exhibiting luminescence propertiestypically observed for Pb$^{2+}$. Effect of concentration of Pb$^{2+}$ ions on emission intensity was studied. The colour co-ordinates of prepared phosphor were calculated and found to lie in the green region of Commission Internationale de l’Eclairagediagram.

• # Bulletin of Materials Science

Volume 45, 2022
All articles
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