Apparent molal volumes of alcohols in aqueous solutions at different temperatures

106-110Apparent molal volumes. (φv) of methyl. ethyl. n-propyl, isopropyl. n-butyl. isobutyl, sec-butyl and lert-butyl alcohols in aqueous solutions are reported at 2°, 4°, 6°, 8°, and 10°C for the first time. The trends of φv against molality (m) curves have been interpreted in terms of effect of dissolved solute (alcohol) on structure of water. It has been concluded that lower alcohols even at lower temperatures get dissolved in the natural cavities available in the water structure whereas higher alcohols have difficulty in finding suitable cavities in water structure and hence tend to indicate phase separation. The results have also been interpreted in terms of predominance of solute-solute interactions at lower temperatures

Luminescence in Ce

A new halosulphate phosphor NaMgSO4F:Ce3+ and Na3SO4F:Ce3+ was synthesized by wet chemical method. The PL emission spectra of phosphors show strong Ce3+ emission due to the $5d\to 4f$ transition of Ce3+ ions. Ce3+ emission in new halosulphates NaMgSO4F and Na3SO4F lattice may be useful for a scintillation application. XRD and photoluminescence (PL) characterization of phosphors has been reported in this paper

<span style="font-size:14.0pt;line-height: 115%;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; color:black;mso-ansi-language:EN-IN;mso-fareast-language:EN-IN;mso-bidi-language: HI" lang="EN-IN">Synthesis of CaB₄O₇:Dy phosphor</span>

299-301<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Synthesis of CaB4O7:Dy phosphors prepared by solid state diffusion technique has been reported. These are shown to be four times sensitive than the commercially used LiF:TLD100 phosphor. The phosphor has a linear response, negligible fading and excellent reusability. This property makes them a suitable replacement for LiF:TLD100 which is currently used for the dosimetry of ionizing radiation using thermo-luminescence.</span

Apparent molal compressibilities of alcohols in aqueous solutions at different temperatures

746-750Apparent molal compressibilities (φk) of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butylalcohols in aqueous solutions are reported at 2, 4, 6, 8 and 10°C. The variation of φk with concentration (m) has been interpreted in terms of effect of dissolved solute (alcohol) on water structure. The limiting apparent molal compressibilities (φ) of alcohols are also reported and interpreted in terms of hydrophobic interactions. In addition, parameter Pθ=(/P) (θstr), where θstr is the structural contribution of shift in temperature of maximum density (Dθ), has been calculated as a function of concentration, It has been observed that Pθ can very well be used as a tool to express the relative structure strengthening ability of dissolved alcohols in water

Combustion synthesis and photoluminescence of Eu²⁺ doped BaB₈O₁₃

441-443The photoluminescence properties of inorganic borate host material BaB8O13 doped with Eu2+ have been studied. The material BaB8O13:Eu2+ was prepared by a novel technique which is a slight variation of solution combustion synthesis. The synthesis is based on the exothermic reaction between the fuel (urea) and oxidizer (ammonium nitrate). The structure of the prepared sample was confirmed by powder XRD technique and photoluminescence properties were investigated. Under UV excitation (254 nm), BaB8O13: Eu2+ shows intense broad emission band peak at 408 nm. The effect of concentration of Eu2+ ions on the PL intensity has also been investigated. It has been observed that the powder sample exhibits highest PL emission intensity for Eu2+ concentration of about 0.03 moles

Phosphors MMgAl₁₀O₁₇: Eu,Dy (M=Ba,Sr,Ca) irradiated by Cs¹³⁷ for thermoluminescence dosimetry

695-697The thermoluminescence (TL) of Eu, Dy activated MMgAl₁₀O₁₇ [M=Ba,Sr,Ca] phosphors has been reported in this paper. These phosphors are prepared by combustion synthesis. TL glow intensity of these phosphors is higher as compared to conventional CaSO₄:Dy TL-phosphor. MMgAl₁₀O₁₇ [M=Ba,Sr,Ca] phosphors may be the possible candidate for thermoluminescence dosimetry of ionizing radiations

TL in halosulphate phosphors prepared by wet chemical method

Polycrystalline halosulphate phosphors are prepared by a wet chemical method. Strong thermoluminescence (TL) was observed in KZnSO4Cl, KMgSO4Cl, Na3SO4F and NaMgSO4F hosts. In these hosts Ce, Dy; Ce, Mn and Ce, Tb the Ce3+ ions acting as sensitizers and Dy3+, Mn2+and Tb3+ ions as activators. The TL glow curves of these halosulphate phosphors exposed to γ-rays for 5 Gy at the rate of 0.995 kGyh-1 are described and discussed first time here

d–f luminescence of Ce3+ and Eu2+ ions in BaAl2O4, SrAl2O4 and CaAl2O4 phosphors

Abstract Ce3+ and Eu2+ doped alkaline earth aluminates MAl2O4 (M = Ca, Sr, Ba) were prepared by single-step combustion synthesis at low temperature (600 °C). X-ray diffraction (XRD) analysis confirmed the formation of BaAl2O4, CaAl2O4, and SrAl2O4. Photoluminescence spectra and optimal luminescent properties of Ce3+ and Eu2+ doped MAl2O4 phosphors were studied. Relation between Eu2+ and Ce3+ f–d transitions was explained. Spectroscopic properties known for Ce3+ were used to predict those of Eu2+ by using Dorenbos’ method. The values thus calculated were in excellent agreement with the experimental results. The preferential substitution of Ce3+ and Eu2+ at different Ba2+, Sr2+, Ca2+ crystallographic sites was discussed. The dependence of emission wavelengths of Ce3+ and Eu2+ on local symmetry of different crystallographic sites was also studied by using Van Uitert’s empirical relation. Experimental results matched excellently with the predictions of Dorenbos’ and Van Uitert’s models