- Email: [email protected]
Preparation and properties of Ce-doped Na–Gd phosphate glasses
Radiation Measurements 38 (2004) 489 – 492 www.elsevier.com/locate/radmeas
Preparation and properties of Ce-doped Na–Gd phosphate glasses M. Rodov&a∗ , A. Cihl&a)r, K. Kn&+z) ek, K. Nitsch, N. Solovieva Optical Crystals Department, Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnick a 10, 162 53 Praha 6, Czech Republic Received 25 November 2003; received in revised form 23 March 2004; accepted 24 March 2004
Abstract Rare earth-doped sodium–gadolinium phosphate glasses with increased luminescence e2ciency are promising materials for the detection of neutrons, - and X-rays. Their main advantages are low cost, high radioluminescence light output, high quality and chemical durability. The glasses were prepared by a rapid quenching technique in air. The radioluminescence intensity maximum was achieved for a Ce concentration of 3 mol% and that of Gd around 30%. Glass transition temperatures were above 300◦ C for the tested samples and this guarantees that the glass can be utilised in a su2ciently broad temperature range. The glass-forming ability of this glass system is high. However, until now high-quality glass has been only prepared with a Gd concentration of 40 mol% in the starting batch. The glasses containing at least 30 mol% Gd were moisture resistant, while those with lower Gd concentrations were slightly hygroscopic. c 2004 Elsevier Ltd. All rights reserved. Keywords: Ce-doped Na–Gd phosphate glasses; Luminescence; Thermal properties
1. Introduction Sodium–gadolinium phosphate glasses doped with rare earth ions show increased luminescence e2ciency (Baccaro et al., 2000; Nikl et al., 2000) and are potential materials for the detection of neutrons, gamma- and X-rays. Increased e2ciency is based on nearly resonant energy migration through the gadolinium subsystem in the glass matrix which is followed by a single-step energy transfer to the rare earth ion emission centres. The radioluminescence light output depends on both Gd and rare earth ion concentrations and is in>uenced by defects in the glass matrix. It was found that the radioluminescence intensity of Ce-doped Na–Gd phosphate glasses increased with Gd concentration. For Gd contents of at least 20 mol%, the intensity, is as much as three times greater than that of equivalently Ce-doped glass without Gd (Nikl et al., 2000). Phosphate glasses of various compositions have been widely studied. The preparation of the Na–Gd phosphate ∗ Corresponding author. Tel.: +420-220-318-429; fax: +420-233-343-184. E-mail address: [email protected] (M. Rodov&a).
c 2004 Elsevier Ltd. All rights reserved. 1350-4487/$ - see front matter doi:10.1016/j.radmeas.2004.03.030
glasses and their optical and thermal properties has been reported previously by our research group (Baccaro et al., 2000; Nikl et al., 2000, 2001; Babin et al., 2003; Vedda et al., 2002; Rodov&a et al., 2003). This contribution deals with the Ce-doped Na–Gd phosphate glasses and presents detailed information about their preparation, relationship between glass composition and radioluminescence characteristics, conditions of formation for stable glasses and their fundamental thermal properties. 2. Experimental Cerium-doped sodium–gadolinium phosphate glasses were prepared by a rapid quenching technique using reagent-grade Na2 CO3 , P2 O5 , GdPO4 and CePO4 . The starting materials in the required molar ratios were melted in a quartz crucible in air at 1200◦ C. After homogenisation the melt was cast into a graphite mould and preheated to 200◦ C. The mould with the sample was tempered for 10 h at this temperature and then slowly cooled to room temperature.
490
M. Rodov a et al. / Radiation Measurements 38 (2004) 489 – 492
DiKerential thermal analysis (DTA) and diKerential scanning calorimetry (DSC) were used to study thermal properties of the prepared glass samples, such as the temperatures of glass transition, crystallisation of the glass and melting of the devitriLed phases. DSC was carried out using a TA Instruments DSC 2920 in the temperature range from 20◦ C to 600◦ C at a heating rate of 10◦ C=min. The mass of the charges was approximately 10 mg. DTA measurements of samples about 20 mg in weight were carried out using a DuPont 990 DTA 910 in the temperature range between 20◦ C and 1000◦ C. Heating rate was 10◦ C=min. DTA and DSC measurements were evaluated using TA Universal Analysis software. Radioluminescence characteristics were measured using a procedure described by Nikl et al. (2000). The glassy state and composition of the devitriLed phases were determined from X-ray diKraction measurements using a Bruker D8 powder diKactometer using CuK -radiation over the 2 angle range from 14 deg to 70 deg. The diKraction patterns were reLned by the program FULLPROF (Rodriguez-Carvajal, 1998) using the structure data of BergerhoK et al. (1983). The chemical durability was evaluated from the changes in sample weight. Samples about 3 × 3 × 3 mm3 in size were kept in a closed jar under water vapour at 25◦ C and regularly weighed. The density of glasses was measured by the Archimedes method with toluene as an immersing medium.
Fig. 1. The X-ray-excited radioluminescence spectra of glasses with compositions 67/30/3 (a), 99/0/1 (b), 74/25/1 (c), 70/30/0 (d).
3. Experimental results and discussion This contribution presents preparation and characterisation of Ce-doped Na–Gd phosphate glasses compositions of which cover the whole concentration range of stable glasses so far prepared. For comparison samples of sodium phosphate glass pure and doped with Ce were also prepared. In the text, the samples are noted as X/Y/Z, where the letters denote the molar concentrations of Na, Gd and Ce in the starting batch. The prepared glass samples were transparent, colourless, without any cracks and 1×1×5 cm3 in size. The samples were classiLed as glasses using X-ray diKraction. Figs. 1 and 2 show X-ray excited radioluminescence spectra of sodium phosphate glasses doped with various Ce and Gd concentrations. Spectra (a) and (d) in Fig. 1 demonstrate the in>uence of Ce concentration (0% and 3%) on the radioluminescence e2ciency of glasses with a Gd concentration of 30 mol%, and spectra (b) and (c) show the in>uence of Gd concentration (0% and 25%) on the radioluminescence e2ciency for glasses containing 1% Ce. SigniLcant diKerences in e2ciency of the Ce emission can be seen for samples with a high Gd concentration (30 mol%) whether or not these samples contain Ce, e.g. compare sample (67/30/3) with sample (70/30/0). The spectra in Fig. 2 show the radioluminescence e2ciency of four samples with diKerent Gd concentrations (0, 20, 30 and 35 mol%). The Ce concentration (3 mol%) is the same in all samples. The
Fig. 2. The X-ray-excited radioluminescence spectra of glasses with compositions 97/0/3 (a),77/20/3 (b), 62/35/3 (c) and 67/30/3 (d).
emission intensity increased with Gd concentration and a maximum was reached at a Gd concentration of 30 mol%. For the sample with 35 mol% Gd (sample 62/35/3) the radioluminescence intensity decreased again. It was found that the radioluminescence e2ciency for Ce doped Na–Gd phosphate glasses reached a maximum for concentrations of 3 and 30 mol% Ce and Gd, respectively. The measured thermal properties of the glasses such as glass transition, crystallisation and melting temperatures are summarised in Table 1 together with their compositions and numerical measure of glass-forming tendency Kgl . Glass
M. Rodov a et al. / Radiation Measurements 38 (2004) 489 – 492
491
Table 1 Composition, thermal properties—temperatures of glass transition (Tg ), crystallisation (Tc ) and melting (Tm ), and numerical measure of glass-forming tendency (Kgl ) of Na–Gd phosphate glasses Composition (mol%) NaPO3 GdPO4 CePO4
100 0 0
90 9 1
69 30 1
50 50
DSC Tg (◦ C) Tc (◦ C) Tm (◦ C)
292 360 573
321 512
394 516
349 570
DTA Tg (◦ C) Tc (◦ C) Tm (◦ C)
290 457 556
322 525 705
380 524 804
363 587 800
Kgl
1.69
1.13
0.51
1.05
Fig. 3. DSC traces of glasses with composition 90/9/1 (a), 100/0/0 (b), 69/30/1 (c) and 50/50/0 (d).
transition temperatures were determined mainly from DSC and range from 300◦ C to 400◦ C, being dependent on glass composition. The measured DSC curves are shown in Fig. 3. All of them exhibited intense endothermic features characterising glass transition. Peaks of further eKects such as crystallisation and melting occurring below 600◦ C were not distinct, but weak and >at. It was impossible to assign them to individual thermal eKects. The DTA was applied for identiLcation of changes in glass occurring above 600◦ C (above the
Fig. 4. Thermal analysis of sample 69/30/1: (a) - DSC, sample as glass, (b) - DTA, sample as glass, (c) - DTA, sample as devitriLed phases after 5 h-annealing at 790◦ C.
temperature range of the DSC). However, DTA traces also exhibited many weak peaks, both exothermic and endothermic, and it was very di2cult to assign them to thermal effects. To identify them, the samples were annealed and measurements were repeated. This process was repeated several times. DSC and DTA traces of sample 69/30/1 as glass and devitriLed phases after 5 h-annealing at 790◦ C are shown in Fig. 4. The DTA and DSC curves of the same glass samples, even those of annealed once were compared and we
492
M. Rodov a et al. / Radiation Measurements 38 (2004) 489 – 492
transition, crystallisation of the glass and melting of the devitriLed phases) were determined by DSC and DTA. The glass samples prepared were stable in a broad temperature range between 300◦ C and 400◦ C. The glass-forming ability of this glass system was evaluated as high. The glasses with Gd content at least 30 mol% are moisture resistant. The paper presents fundamental information about the materials parameters of Ce-doped Na–Gd phosphate glasses, but further detailed studies are necessary in order to improve glass quality including chemical resistivity, to widen the composition range of glass stability and to enhance the radioluminescence light output.
Fig. 5. Weight increase of glasses after keeping in water vapour at 25◦ C for 120 (dependence - a) and 430 h (dependence - b).
searched for eKects occurring at the same temperatures. Individual thermal eKects were determined by this procedure and the false ones were ignored. Nevertheless, the correct determination of thermal eKects from DTA was di2cult. The glass-forming ability of our glass system was evaluated according to the relation Kgl = (Tc − Tg )=(Tm − Tc );
(1)
where Kgl is the numerical measure of glass forming tendency, Tg , Tc and Tm are the glass transition, crystallisation and melting temperatures. If the Kgl is greater than 0.5 the glass should be easily prepared even at a low cooling rate (Hrub&y, 1972). For all the glass samples the value of Kgl is greater than 0.5 (see Table 1), which means that the glass forming ability of our glass system is high. However, if the Na concentration decreased below 60 mol% in the starting batch, the Lrst vitrescence di2culties appeared connected with the formation of inhomogenities and precipitates in the glasses. Results of chemical resistance of glasses against water steam evaluated by weight increase after 120 and 430 h are shown in Fig. 5. Whereas the glass samples with Gd content greater than 30 mol% were moisture resistant, that with 10 mol% Gd was slightly hygroscopic and pure sodium phosphate even dissolves in absorbed water. The density of tested samples depends Lrst of all on Gd concentration and ranges from 2.54 for pure sodium phosphate to 3:36 g=cm3 for glass containing as many as 50 mol% Gd in the starting batch. 4. Conclusions The Ce doped Na–Gd phosphate glass samples of high quality with Gd concentration of as high as 40 mol% in the starting batch were prepared by the rapid quenching technique in air. Their thermal properties (temperatures of glass
Acknowledgements This research was supported by Grant No. A2010304 of the Grant Agency of the AS CR and NATO Science for Peace Grant No. 973510-Scintillators. The access to the ICSD was enabled by Grant No. 203/02/0436 of the Grant Agency of the Czech Republic. References Babin, V., Krasnikov, A., Mare)s, J.A., Nikl, M., Nitsch, K., Solovieva, N., Zazubovich, S., 2003. Luminescence spectroscopy of the Gd-rich Ce3+ -Tb3+ - and Mn2+ -doped phosphate glasses. Phys. Stat. Sol. (a) 196, 484–495. Baccaro, S., Dall’Igna, R., Fabeni, P., Martini, M., Mare)s, J.A., Meinardi, F., Nikl, M., Nitsch, K., Pazzi, G.P., Polato, P., Susini, C., Vedda, A., Zanella, G., Zannoni, R., 2000. Ce3+ or Tb3+ -doped phosphate and silicate scintillating glasses. J. Lumin. 87–89, 673–675. BergerhoK, G., Hundt, R., Sievers, R., Brown, I.D., 1983. Inorganic Crystal Structure Database. J. Chem. Inform. Comput. Sci. 23, 66–69. Hrub&y, A., 1972. Evaluation of glass-forming tendency by means of DTA. Czech. J. Phys. B 22, 1187–1193. Nikl, M., Nitsch, K., Mih&o kov&a, E., Solovieva, N., Mare)s, J.A., Fabeni, P., Pazzi, G.P., Martini, M., Vedda, A., Baccaro, S., 2000. E2cient radioluminescence of the Ce3+ -doped Na–Gd phosphate glasses. Appl. Phys. Lett. 77, 2159–2161. Nikl, M., Mare)s, J.A., Mihokov&a, E., Nitsch, K., Solovieva, N., Babin, V., Krasnikov, A., Zazubovich, S., Martini, M., Vedda, A., Fabeni, P., Pazzi, G.P., Baccaro, S., 2001. Radio- and thermoluminescence and energy transfer processes in Ce3+ (Tb3+ )-doped phosphate glasses. Radiat. Meas. 33, 593–596. Rodov&a, M., Bro)zek, J., Cihl&a)r, A., Nitsch, K., 2003. Thermal properties of Na–Gd phosphate scintillating glasses. Proceedings of the “Calorimetry Seminar 2003”, ISBN 80-7042-836-8, Such&a Rudn&a, pp. 99–102 (in Czech). Rodriguez-Carvajal, J., FULLPROF 98, March 1998, Laboratoire Leon Brillouin CEA-CNRS. Vedda, A., Martini, M., Nikl, M., Mih&okov&a, E., Nitsch, K., Solovieva, N., 2002. Optical absorption and thermoluminescence of Tb3+ -doped phosphate scintillating glasses. J. Phys.: Condens. Matter 14, 7417–7426.
Preparation and properties of Ce-doped Na–Gd phosphate glasses M. Rodov&a∗ , A. Cihl&a)r, K. Kn&+z) ek, K. Nitsch, N. Solovieva Optical Crystals Department, Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnick a 10, 162 53 Praha 6, Czech Republic Received 25 November 2003; received in revised form 23 March 2004; accepted 24 March 2004
Abstract Rare earth-doped sodium–gadolinium phosphate glasses with increased luminescence e2ciency are promising materials for the detection of neutrons, - and X-rays. Their main advantages are low cost, high radioluminescence light output, high quality and chemical durability. The glasses were prepared by a rapid quenching technique in air. The radioluminescence intensity maximum was achieved for a Ce concentration of 3 mol% and that of Gd around 30%. Glass transition temperatures were above 300◦ C for the tested samples and this guarantees that the glass can be utilised in a su2ciently broad temperature range. The glass-forming ability of this glass system is high. However, until now high-quality glass has been only prepared with a Gd concentration of 40 mol% in the starting batch. The glasses containing at least 30 mol% Gd were moisture resistant, while those with lower Gd concentrations were slightly hygroscopic. c 2004 Elsevier Ltd. All rights reserved. Keywords: Ce-doped Na–Gd phosphate glasses; Luminescence; Thermal properties
1. Introduction Sodium–gadolinium phosphate glasses doped with rare earth ions show increased luminescence e2ciency (Baccaro et al., 2000; Nikl et al., 2000) and are potential materials for the detection of neutrons, gamma- and X-rays. Increased e2ciency is based on nearly resonant energy migration through the gadolinium subsystem in the glass matrix which is followed by a single-step energy transfer to the rare earth ion emission centres. The radioluminescence light output depends on both Gd and rare earth ion concentrations and is in>uenced by defects in the glass matrix. It was found that the radioluminescence intensity of Ce-doped Na–Gd phosphate glasses increased with Gd concentration. For Gd contents of at least 20 mol%, the intensity, is as much as three times greater than that of equivalently Ce-doped glass without Gd (Nikl et al., 2000). Phosphate glasses of various compositions have been widely studied. The preparation of the Na–Gd phosphate ∗ Corresponding author. Tel.: +420-220-318-429; fax: +420-233-343-184. E-mail address: [email protected] (M. Rodov&a).
c 2004 Elsevier Ltd. All rights reserved. 1350-4487/$ - see front matter doi:10.1016/j.radmeas.2004.03.030
glasses and their optical and thermal properties has been reported previously by our research group (Baccaro et al., 2000; Nikl et al., 2000, 2001; Babin et al., 2003; Vedda et al., 2002; Rodov&a et al., 2003). This contribution deals with the Ce-doped Na–Gd phosphate glasses and presents detailed information about their preparation, relationship between glass composition and radioluminescence characteristics, conditions of formation for stable glasses and their fundamental thermal properties. 2. Experimental Cerium-doped sodium–gadolinium phosphate glasses were prepared by a rapid quenching technique using reagent-grade Na2 CO3 , P2 O5 , GdPO4 and CePO4 . The starting materials in the required molar ratios were melted in a quartz crucible in air at 1200◦ C. After homogenisation the melt was cast into a graphite mould and preheated to 200◦ C. The mould with the sample was tempered for 10 h at this temperature and then slowly cooled to room temperature.
490
M. Rodov a et al. / Radiation Measurements 38 (2004) 489 – 492
DiKerential thermal analysis (DTA) and diKerential scanning calorimetry (DSC) were used to study thermal properties of the prepared glass samples, such as the temperatures of glass transition, crystallisation of the glass and melting of the devitriLed phases. DSC was carried out using a TA Instruments DSC 2920 in the temperature range from 20◦ C to 600◦ C at a heating rate of 10◦ C=min. The mass of the charges was approximately 10 mg. DTA measurements of samples about 20 mg in weight were carried out using a DuPont 990 DTA 910 in the temperature range between 20◦ C and 1000◦ C. Heating rate was 10◦ C=min. DTA and DSC measurements were evaluated using TA Universal Analysis software. Radioluminescence characteristics were measured using a procedure described by Nikl et al. (2000). The glassy state and composition of the devitriLed phases were determined from X-ray diKraction measurements using a Bruker D8 powder diKactometer using CuK -radiation over the 2 angle range from 14 deg to 70 deg. The diKraction patterns were reLned by the program FULLPROF (Rodriguez-Carvajal, 1998) using the structure data of BergerhoK et al. (1983). The chemical durability was evaluated from the changes in sample weight. Samples about 3 × 3 × 3 mm3 in size were kept in a closed jar under water vapour at 25◦ C and regularly weighed. The density of glasses was measured by the Archimedes method with toluene as an immersing medium.
Fig. 1. The X-ray-excited radioluminescence spectra of glasses with compositions 67/30/3 (a), 99/0/1 (b), 74/25/1 (c), 70/30/0 (d).
3. Experimental results and discussion This contribution presents preparation and characterisation of Ce-doped Na–Gd phosphate glasses compositions of which cover the whole concentration range of stable glasses so far prepared. For comparison samples of sodium phosphate glass pure and doped with Ce were also prepared. In the text, the samples are noted as X/Y/Z, where the letters denote the molar concentrations of Na, Gd and Ce in the starting batch. The prepared glass samples were transparent, colourless, without any cracks and 1×1×5 cm3 in size. The samples were classiLed as glasses using X-ray diKraction. Figs. 1 and 2 show X-ray excited radioluminescence spectra of sodium phosphate glasses doped with various Ce and Gd concentrations. Spectra (a) and (d) in Fig. 1 demonstrate the in>uence of Ce concentration (0% and 3%) on the radioluminescence e2ciency of glasses with a Gd concentration of 30 mol%, and spectra (b) and (c) show the in>uence of Gd concentration (0% and 25%) on the radioluminescence e2ciency for glasses containing 1% Ce. SigniLcant diKerences in e2ciency of the Ce emission can be seen for samples with a high Gd concentration (30 mol%) whether or not these samples contain Ce, e.g. compare sample (67/30/3) with sample (70/30/0). The spectra in Fig. 2 show the radioluminescence e2ciency of four samples with diKerent Gd concentrations (0, 20, 30 and 35 mol%). The Ce concentration (3 mol%) is the same in all samples. The
Fig. 2. The X-ray-excited radioluminescence spectra of glasses with compositions 97/0/3 (a),77/20/3 (b), 62/35/3 (c) and 67/30/3 (d).
emission intensity increased with Gd concentration and a maximum was reached at a Gd concentration of 30 mol%. For the sample with 35 mol% Gd (sample 62/35/3) the radioluminescence intensity decreased again. It was found that the radioluminescence e2ciency for Ce doped Na–Gd phosphate glasses reached a maximum for concentrations of 3 and 30 mol% Ce and Gd, respectively. The measured thermal properties of the glasses such as glass transition, crystallisation and melting temperatures are summarised in Table 1 together with their compositions and numerical measure of glass-forming tendency Kgl . Glass
M. Rodov a et al. / Radiation Measurements 38 (2004) 489 – 492
491
Table 1 Composition, thermal properties—temperatures of glass transition (Tg ), crystallisation (Tc ) and melting (Tm ), and numerical measure of glass-forming tendency (Kgl ) of Na–Gd phosphate glasses Composition (mol%) NaPO3 GdPO4 CePO4
100 0 0
90 9 1
69 30 1
50 50
DSC Tg (◦ C) Tc (◦ C) Tm (◦ C)
292 360 573
321 512
394 516
349 570
DTA Tg (◦ C) Tc (◦ C) Tm (◦ C)
290 457 556
322 525 705
380 524 804
363 587 800
Kgl
1.69
1.13
0.51
1.05
Fig. 3. DSC traces of glasses with composition 90/9/1 (a), 100/0/0 (b), 69/30/1 (c) and 50/50/0 (d).
transition temperatures were determined mainly from DSC and range from 300◦ C to 400◦ C, being dependent on glass composition. The measured DSC curves are shown in Fig. 3. All of them exhibited intense endothermic features characterising glass transition. Peaks of further eKects such as crystallisation and melting occurring below 600◦ C were not distinct, but weak and >at. It was impossible to assign them to individual thermal eKects. The DTA was applied for identiLcation of changes in glass occurring above 600◦ C (above the
Fig. 4. Thermal analysis of sample 69/30/1: (a) - DSC, sample as glass, (b) - DTA, sample as glass, (c) - DTA, sample as devitriLed phases after 5 h-annealing at 790◦ C.
temperature range of the DSC). However, DTA traces also exhibited many weak peaks, both exothermic and endothermic, and it was very di2cult to assign them to thermal effects. To identify them, the samples were annealed and measurements were repeated. This process was repeated several times. DSC and DTA traces of sample 69/30/1 as glass and devitriLed phases after 5 h-annealing at 790◦ C are shown in Fig. 4. The DTA and DSC curves of the same glass samples, even those of annealed once were compared and we
492
M. Rodov a et al. / Radiation Measurements 38 (2004) 489 – 492
transition, crystallisation of the glass and melting of the devitriLed phases) were determined by DSC and DTA. The glass samples prepared were stable in a broad temperature range between 300◦ C and 400◦ C. The glass-forming ability of this glass system was evaluated as high. The glasses with Gd content at least 30 mol% are moisture resistant. The paper presents fundamental information about the materials parameters of Ce-doped Na–Gd phosphate glasses, but further detailed studies are necessary in order to improve glass quality including chemical resistivity, to widen the composition range of glass stability and to enhance the radioluminescence light output.
Fig. 5. Weight increase of glasses after keeping in water vapour at 25◦ C for 120 (dependence - a) and 430 h (dependence - b).
searched for eKects occurring at the same temperatures. Individual thermal eKects were determined by this procedure and the false ones were ignored. Nevertheless, the correct determination of thermal eKects from DTA was di2cult. The glass-forming ability of our glass system was evaluated according to the relation Kgl = (Tc − Tg )=(Tm − Tc );
(1)
where Kgl is the numerical measure of glass forming tendency, Tg , Tc and Tm are the glass transition, crystallisation and melting temperatures. If the Kgl is greater than 0.5 the glass should be easily prepared even at a low cooling rate (Hrub&y, 1972). For all the glass samples the value of Kgl is greater than 0.5 (see Table 1), which means that the glass forming ability of our glass system is high. However, if the Na concentration decreased below 60 mol% in the starting batch, the Lrst vitrescence di2culties appeared connected with the formation of inhomogenities and precipitates in the glasses. Results of chemical resistance of glasses against water steam evaluated by weight increase after 120 and 430 h are shown in Fig. 5. Whereas the glass samples with Gd content greater than 30 mol% were moisture resistant, that with 10 mol% Gd was slightly hygroscopic and pure sodium phosphate even dissolves in absorbed water. The density of tested samples depends Lrst of all on Gd concentration and ranges from 2.54 for pure sodium phosphate to 3:36 g=cm3 for glass containing as many as 50 mol% Gd in the starting batch. 4. Conclusions The Ce doped Na–Gd phosphate glass samples of high quality with Gd concentration of as high as 40 mol% in the starting batch were prepared by the rapid quenching technique in air. Their thermal properties (temperatures of glass
Acknowledgements This research was supported by Grant No. A2010304 of the Grant Agency of the AS CR and NATO Science for Peace Grant No. 973510-Scintillators. The access to the ICSD was enabled by Grant No. 203/02/0436 of the Grant Agency of the Czech Republic. References Babin, V., Krasnikov, A., Mare)s, J.A., Nikl, M., Nitsch, K., Solovieva, N., Zazubovich, S., 2003. Luminescence spectroscopy of the Gd-rich Ce3+ -Tb3+ - and Mn2+ -doped phosphate glasses. Phys. Stat. Sol. (a) 196, 484–495. Baccaro, S., Dall’Igna, R., Fabeni, P., Martini, M., Mare)s, J.A., Meinardi, F., Nikl, M., Nitsch, K., Pazzi, G.P., Polato, P., Susini, C., Vedda, A., Zanella, G., Zannoni, R., 2000. Ce3+ or Tb3+ -doped phosphate and silicate scintillating glasses. J. Lumin. 87–89, 673–675. BergerhoK, G., Hundt, R., Sievers, R., Brown, I.D., 1983. Inorganic Crystal Structure Database. J. Chem. Inform. Comput. Sci. 23, 66–69. Hrub&y, A., 1972. Evaluation of glass-forming tendency by means of DTA. Czech. J. Phys. B 22, 1187–1193. Nikl, M., Nitsch, K., Mih&o kov&a, E., Solovieva, N., Mare)s, J.A., Fabeni, P., Pazzi, G.P., Martini, M., Vedda, A., Baccaro, S., 2000. E2cient radioluminescence of the Ce3+ -doped Na–Gd phosphate glasses. Appl. Phys. Lett. 77, 2159–2161. Nikl, M., Mare)s, J.A., Mihokov&a, E., Nitsch, K., Solovieva, N., Babin, V., Krasnikov, A., Zazubovich, S., Martini, M., Vedda, A., Fabeni, P., Pazzi, G.P., Baccaro, S., 2001. Radio- and thermoluminescence and energy transfer processes in Ce3+ (Tb3+ )-doped phosphate glasses. Radiat. Meas. 33, 593–596. Rodov&a, M., Bro)zek, J., Cihl&a)r, A., Nitsch, K., 2003. Thermal properties of Na–Gd phosphate scintillating glasses. Proceedings of the “Calorimetry Seminar 2003”, ISBN 80-7042-836-8, Such&a Rudn&a, pp. 99–102 (in Czech). Rodriguez-Carvajal, J., FULLPROF 98, March 1998, Laboratoire Leon Brillouin CEA-CNRS. Vedda, A., Martini, M., Nikl, M., Mih&okov&a, E., Nitsch, K., Solovieva, N., 2002. Optical absorption and thermoluminescence of Tb3+ -doped phosphate scintillating glasses. J. Phys.: Condens. Matter 14, 7417–7426.