A new phosphor Na21Mg(SO4)10Cl3 is very interesting for photoluminescence (PL) properties. In this paper we present results concerning the main PL properties of Na21Mg(SO4)10Cl3 activated by Ce at various concentrations. Polycrystalline Na21Mg(SO4)10Cl3: Ce phosphor prepared by wet chemical method have been studied for its PL characteristics showing Ce3+ emission at 341 nm at the excitation of 247 nm due to 5d &rarr; 4f transition, This is a good result for the materials which can be used in scintillation applications

Dhoble, S J

Gedam, S C

Poddar, Anuradha

English

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Recent Research in Science and Technology 2012, 4(8): 52-54 ISSN: 2076-5061 Available Online: http://recent-science.com/     Study of crystal structure and PL properties of Na21Mg(SO4)10Cl3 :Ce halophosphor  Anuradha Poddar 1, S. C. Gedam 2* and S.J. Dhoble3  1 Department of Physics, Sindhu College, Nagpur, - 440017, India 2 Department of Physics, K.Z.S. Science College, Kalmeshwar, Nagpur - 441501, India 3 Department of Physics, RTM Nagpur University, Nagpur- 440033, India  Abstract  A new phosphor Na21Mg(SO4)10Cl3 is very interesting for photoluminescence (PL) properties. In this paper we present results concerning the main PL properties of Na21Mg(SO4)10Cl3 activated by Ce at various concentrations. Polycrystalline Na21Mg(SO4)10Cl3: Ce phosphor prepared by wet chemical method have been studied for its PL characteristics showing Ce3+ emission at 341 nm at the excitation of 247 nm due to 5d → 4f transition, This is a good result for the materials which can be used in scintillation applications.  Keywords: Photoluminescence; wet chemical; luminescence spectroscopy.  INTRODUCTION       Luminescence spectroscopy is particularly important in the characterization of materials that contain significant proportions of noncrystalline components, multiple phases, or low concentrations of mineral phases. A number of minerals have distinguishing luminescence properties. These include: diamond, sulphides (chalcocite, sphalerite), oxides (periclase, corundum, cassiterite), halides (fluorite, halite), sulphates (anhydrite, alunite), wolframates (scheelite), phosphates (apatite), carbonates (calcite, dolomite, magnesite, witherite), or silicates (albite, feldspar, quartz, zeolites, kaolinite, forsterite, zircon, garnet, titanite, thorite, willemite). However, the group of sulfate apatites has not been studied in such detail in the field of luminescence. The Cl-F substitution in the system Ca10(PO4)6(FxCl1-x)2 has been investigated by Mackie and Young [1]. Klement [2] synthesized the sulfate apatite Na6Ca4(SO4)6F2 and characterized this compound by X-ray powder diffraction. Also, the compounds Na6Pb4(SO6)4Cl2 (Caracolite) [3, 4], Na6Cd4(SO6)4Cl2 [5], Na6Ca4(SO6)4Cl2 (Cesanite) [6,7] are known as members of the sulfate apatite group, all crystallizing in space group P6_/m. The apatite-like compound K6Ca4(SO4)6F2 was described by Vazquez [8] and Fayos et al. [9].       Thermoluminescence (TL) technique has wide range of applications such as in radiation dosimetry and to dating techniques in archeology and geology. TL studies are also useful for the study of lattice defects which acts as “traps” to electrons and holes. Analysis of TL glow curves has become more important in view of its applications in dating, dosimetry and defect studies.      In this paper we present the detail studies of a new host Na21Mg(SO4)10Cl3 such as its crystal structure, PL. The crystal Structure data of Na21Mg(SO4)10Cl3 [10] is given here in Figure 2. As per the literature available, the minerological name of Na21Mg(SO4)10Cl3 is d’ansite [11], the name is given in the honour of Professor Jean D’Ans (1881–1969), German mineralogist, student of salt deposit chemistry, Technical University, Berlin, Germany. D’ansite occurs as a component of marine evaporite deposits, n.d. type material. It is semitransparent, colorless, yellow, pale brown having, optical class: Isotropic. n = 1.488–1.489.                 We have reported some inorganic materials as phosphors [12-22]. The KZnSO4Cl: Ce, Mn and KMgSO4Cl: Ce, Mn phosphors were prepared by wet chemical synthesis method. Other than these materials, KZnSO4Cl:Ce; Ce, Dy and KMgSO4Cl:Ce; Ce, Dy; KMgSO4Cl:Eu; Na3SO4F: Ce; NaMgSO4Cl:Ce; KCaSO4Cl: Ce; Dy have been reported as phosphors by wet chemical , solid state diffusion and melting route and characterized XRD, photoluminescence (PL), thermoluminescence (TL). Here we report Na21Mg(SO4)10Cl3 as a host for luminescent (PL and TL) material by doping Ce and Dy first time. Excellent photoluminescence (PL) and thermoluminescence (TL) results are observed. The phosphor may be used as a TLD material.                EXPERIMENTAL                       Na21Mg(SO4)10Cl3 (pure) and Na21Mg(SO4)10Cl3: Ce phosphors were prepared by a wet chemical method. MgSO4 and Na2SO4 and NaCl of AR grade were taken in a stoichimetric ratio and dissolved separately in double distilled de-ionized water, resulting in a solution of Na21Mg(SO4)10Cl3. Then water-soluble sulphate salt of Cerium was added to the solution to obtain Na21Mg(SO4)10Cl3: Ce. Confirming that no undissolved constituents were left behind, and all the salts had completely dissolved in water and thus reacted.      9 Na2SO4 + 3 NaCl + MgSO4  →   Na21Mg(SO4)10Cl3       The compounds Na21Mg(SO4)10Cl3 (pure) and Na21Mg(SO4)10Cl3: Ce in its powder form was obtained by evaporating on 80 0c for 8 hours. The dried samples were then slowly cooled at room temperature. The resultant polycrystalline mass was crushed to fine particle in a crucible. The powder was used in further study. Formation of the compounds was confirmed by taking the x-ray diffraction (XRD) pattern that matched with the standard data available. The photoluminescence (PL) emission spectra of the samples were recorded using Fluorescence spectrometer (Hitachi F-4000). The same amount of sample was used in each case. Emission and excitation spectra were recorded using a spectral slit width of 1.5 nm.   RESULTS AND DISCUSSION    Study of XRD and Crystal Structure Recent Research in Science and Technology 2012, 4(8): 52-54  53     Figure 1 shows X-Ray diffraction pattern of Na21Mg(SO4)10Cl3 material that matched with the standard JCPDF data No. 41-1473. The XRD pattern did not indicate the presence of the constituents such as Na2SO4, MgSO4 or NaCl and other likely phases, which is the direct evidence for the formation of the desired compound. These results indicate that the final product was formed in homogeneous form.According to the data available the D’ansite crystal structure has the following parameters; Crystal Data: Cubic. Point Group: 43m. as tetrahedral {211} crystals, modified by {211} and {110}. Polysynthetic twinning observed. Hardness = 2.5–3 D (meas.) = 2.63–2.655 D (calc.) =2.60 Soluble in H2O, Space Group: I43m. a = 15.95 Z = 4, Synthetic. (ICDD 41-1473). 3.396 (100), 2.815 (100), 3.123 (60), 2.584 (40), 4.257 (30), 3.982 (30), 2.518 (25), symmetry class: cubic, space group: I 4(3d, unit cell parameters: a = 15.9130, unit cell volume, Å:  Vc = 4029.55, number of atomic position per full unit cell, P/U = 324, molar volume, Vm = 606.79 cm3/mol, number of reflexes used in structure determination, NR = 810, X-ray density, ρ = 2.66 g/cm3,  R-factor, R = 0.0360, MU, 1/cm, µ = 108.219, wavelength for calculated powder diffraction pattern Cu=1.54056, mass attenuation coefficient (µ/p) = 40.662 cm2/g,  theta-interval for CPDP (T/I) = 1-45.  Fig 1. XRD pattern of Na21Mg(SO4)10Cl3   Fig 2. Crystal structure of Na21Mg(SO4)10Cl3 (Ref.10).  Photoluminescence (PL) in Na21Mg(SO4)10Cl3: Ce3+       Figure 3 shows the PL excitation spectra of Na21Mg(SO4)10Cl3:Ce3+ phosphor (λem= 341nm), broadband is observed at around 247nm. Figure 4 shows the PL emission spectra of Ce3+ ions in Na21Mg(SO4)10Cl3 phosphor with different concentration under excitation of 247nm wavelength of light. Peak is observed at 341nm, which are assigned to the 5d→ 4f transition of Ce3+ ions. With increasing concentration of Ce3+ ions the peak intensity of 341nm, increases the maximum intensity observed for 5-mole % concentration of Ce3+ ions (Figure 5). This indicates that the Na21Mg(SO4)10Cl3 lattice is more suitable for higher concentrations of Ce3+ions. Figure 6 indicates the energy level diagram for Na21Mg(SO4)10Cl3: Ce3+.        The PL emission spectra of Na21Mg(SO4)10Cl3: Ce3+ (5mole%) phosphors show very strong Ce3+ emission at 341nm due to 5d→ 4f transition of Ce3+ ions. The variation of PL emission intensity observed may be due to cross relaxation between Ce3+ ions in case of heavy concentration of Ce3+. The strong Ce3+ emission in Na21Mg(SO4)10Cl3 lattice may be useful for a scintillator. PL emission peak intensity of Ce3+ ion in Na21Mg(SO4)10Cl3 lattice is not having the same intensity for different concentration of Ce3+ ions. The PL emission peak intensity dependent on the concentration of Ce3+ ion. The intensity of Ce3+ ion in above phosphor shows the maximum Ce3+ emission observed in Ce (5 mole%) phosphor. Ce3+ phosphors are useful where rapid decay times are required (e.g. in time of flight camera and in scintillator), however quantum efficiency and other related measurements should be done. It can be used as a sensitizer for other rare earths.  Fig 3. Excitation spectra of Na21Mg(SO4)10Cl3:Ce (λex = 247nm) for the λem = 341 nm   Fig 4. PL emission spectra Na21Mg(SO4)10Cl3:Ce 5mole% b) 2 mole%  c) 1 mole% (exci at 247nm)   Poddar et al.,   54Fig 5. Effect on intensity with variation in concentrations in Na21Mg(SO4)10Cl3:Ce   Fig 6. Schematic energy level diagram of Ce3+ in Na21Mg(SO4)10Cl3:Ce  CONCLUSION       Na21Mg(SO4)10Cl3: Dy3+, Ce3+ and Dy3+ has been prepared by wet chemical method and characterized on the basis of its PL and TL characteristics. The results show a Strong PL emission of Ce3+ at 341 nm due to 5d→ 4f transition of Ce3+ ion and Dy3+ ions is observed at 483 and 577 nm due to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transition respectively. The main property of Na21Mg(SO4)10Cl3: Ce or Dy is its good PL and TL sensitivity.  ACKNOWLEDGEMENT       One of us SCG is thankful to University Grant Commission, New Delhi, India and SJD is thankful to BRNS Govt. of India for financial assistance during the work.   REFERENCES  [1] P. E. Mackie and R. A. Young, J. Solid State Chem. 11 (1974) 176. [2] R. Klement, Naturwissenschaften 27 (1939) 568. [3] W. Schneider, N. Jahrb. f. Miner. Monatshefte, (1967) 284. [4] W. Schneider, N. Jahrb. f. Miner. Monatshefte, (1969) 58.  [5] R. Perret and A. M. Bouillet, Bull. Soc. 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Study of crystal structure and PL properties of Na21Mg(SO4)10Cl3 :Ce halophosphor

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Study of crystal structure and PL properties of Na21Mg(SO4)10Cl3 :Ce halophosphor

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