Detection of Impurities in Nd Doped Phosphate Laser Glass

Detection of Impurities in Nd Doped Phosphate Laser GlassDetection of the impurities in Nd doped inorganic inorganic phosphate optical maser methamphetamine hydrochloride by roentgen ray fluorescence proficiencyAtul Kumar*, M. P. Kamath, A. S. Joshi, P. A. Naik, P. D. GuptaLaser Plasma DivisionA. K. Singh, M. K. TiwariIndus Synchrotrons Utilization Divisiongenus Raja Ramanna Centre for Advanced engine room, Indore 452013, M.P., India*Email emailprotectedIntroductionThe advances in laser spy provide composition and manufacturing have enabled the development of third generation high nil high power (HEHP) lasers like the National Ignition facility (NIF)1 that argon being used as drivers for fusion energy studies. These laser furnish are phosphate based be accept of their low intensity dependent refractive index n2 and have a compositions equivalent to LHG-8 of M/s Hoya, lacquer or LG-770 frappe of M/s Schott Ltd2. The manufacturing and intervention procedures introduce ma ny a(prenominal) an(prenominal) unwanted impurities in these supply, leading to lower laser induced reproach threshold and lower fluorescence life time. The roentgenogram fluorescence (XRF) is a powerful technique3 which cease identify the elemental composition of such render in a non-destructive manner. In the XRF process, the specimen is excited with high energy photons, which nookie cause individual atoms to ionize. When these atoms undergo relaxation, the electrons relocate from a high energy orbital to a lower one. During this process, fluorescence radiation is emitted. The emitted radiation has lower energy compared to the hazard source and it depends on the specific electron conversions of the individual elements. Thus, the resulting x-ray fluorescence spectrum bears the jot of the elements present in the specimen.In the present say, we have perform XRF analysis on incompatible laser film over savors and affectionate stuff and nonsenses used for the parable of these spectacles namely aluminum metaphosphate (AMP), barium metaphosphate (BMP) and potassium metaphosphate (KMP). The advantage of the this study is that it can indicate to the presence of most of the impurities like transition metal impurities (of quest to us) in one measurement, if their concentrations are of the order of few ppm (by weight) or more. Our studies on the glasses and the lancinating materials indicate that the warm materials are pure to the coveted levels but the glasses pretended using the raw materials show many impurities. These impurities are expected to enter during discourse of the raw materials and from the glass-cullet during fabrication process. This study go away help in improving the prime(prenominal) of the glass by repeatedly doing the XRF analysis after every stage, so that faulty handling can be identified.Method of fabrication of the phosphate laser glassA two arm HEHP Ndphosphate glass laser chain is operational at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore4. A joint collaborative project is undertaken with Central Glass and ceramic Research Institute (CGCRI), Kolkata to develop the process technology for the fabrication of the phosphate laser glasses equivalent to LHG-8 glass of M/s Hoya, to outstrip the existing embargo. The phosphate laser glass is fabricated as a two step process. In the first step, the sintered raw material (AMP, BMP and KMP and Nd2O3 in appropriate fractions) is melted in a silica crucible. The glass-cullet produced as a result of melting in the silica crucible is roll out. The cast glass is powdered and loaded in a bottom burbling platinum crucible for optical quality, and chemical and physical homogenization. During these steps in the fabrication, the impurities whitethorn be added to the glass at several stages, namely a) flux of the raw materials, b) impurities coming from the silica crucible, c) impurities coming from the glass-cullet cast, d) impurities coming from the platinum crucible, e) impurities coming during annealing and fine annealing of the glass.Six samples of laser glass (named LG-1 to LG-6) were fabricated at CGCRI for the studies. XRF analysis was done on different fabricated samples of laser glasses (LG-1 to LG-6) and raw material samples made from AMP, BMP and KMP, to identify the elemental impurities in laser glass and raw materials. In accession to this, the sensitivity of the XRF technique was besides ascertained using small amounts of platinum deliberately added to the glass samples.Experiments and MethodologyXRF analysis was performed at the BL-16 beamline of Indus-2 synchrotron facility5 on fabricated glass samples and the raw materials after the first step of melting in silica crucible. The glasses had platinum oxide dissolved in them because of its solubility in the laser glass. atomic number 78 comes into the glass as an unavoidable impurity during homogenization of the glass in the platinum crucible. Metallic plati num absorbs at the lasing wavelength (1054 nm) and reduces the laser induced suffering threshold (LIDT) of the laser glass. Oxygen bubbling is done in platinum crucible to reduce the OH bond impurity in the hygroscopic phosphate glass. The oxygen bubbling also oxidizes the platinum metal to its oxide, thereby simplification the metallic platinum in the glass. The other impurities occur because of the suffering quality of the silica crucible and/or cast of glass-cullet in addition to poor handling during the mixing of the raw materials in the first step of melting.The glasses with different amounts of platinum oxide were LG-1(5 ppm Pt), LG-2 (10 ppm Pt), LG-3(25 ppm Pt), LG-4 (5 ppm Pt with O2 bubbling), LG-5 (10 ppm Pt with O2 bubbling) and LG-6 (25 ppm Pt with O2 bubbling). Varying platinum oxide content helped in ascertaining the sensitivity of the technique to Pt impurity. In the experiment, an x-ray beam was incident on sample for excitation and scattered spectrum was save by the detector shown in Fig. 1. The samples were excited using 14 keV and 17 keV synchrotron x-rays, selected by a double-crystal monochromator system. The analyses have been done on all the raw powder materials (for qualitative analysis) and on the pallets (for quantitative analysis). 15 mm dia. pallets were formed using a semi-automatic pallet machine. One such pallet is shown in sample holder in Fig. 1. go in 1 Raw specimens analyze by XRF measurementsThe captured data was analyzed using the PyMCA software 6. The calibration of the deliberate fluorescence spectrum was achieved by selecting the K lines of various elements present in the laser glass samples, and in the raw material samples. The method of spectrum calibration however require a proper comparison with a standard doped sample as a confirmatory test to account for the variation in the actual composition of the fabricated laser glass samples and that measured with XRF. In the present study, XRF method was used to qualit atively see the presence of different impurities, strictly from the yes/no point of view, rather than the full quantitative estimation.Results and banterFigure 2 shows a typical spectrum of the fabricated LG-1 glasses and the raw material BMP. The impurities found in the fabricated glasses are listed in Table 1. The silicon impurity occurs because of melting in silica crucible. Sr impurity seen in BMP as Ba and Sr are chemically close to each other. For the same reason, Rb impurity was found in KMP. However, there no impurities were seen in AMP. The transition metal impurities however may come either from during handling of raw materials or through the casts of glass-cullet. This will be ascertained in future by cast the glass in casts made of different materials like graphite, aluminum, and stainless steel. The studies of impurities after the casting of the glass will give idea about its origin. In addition to this, the XRF technique was found to be sensitive to 5 ppm of Pt impu rities.Figure 2 a) Typical spectrum of a) LG-1 fabricated glass, and b) Barium meta-phosphate specimen (raw material)Table 1 List of the impurities present in the glass samplesSummaryWe have presented XRF analysis on different laser glasses (LG-1 to LG-6) and raw materials (AMP, BMP and KMP) used for the fabrication of such glasses. The impurities in these glasses may be entering during handling or coming from the silica crucible, or the cast for the glass-cullet. The XRF method was also found to be sensitive up to 3 ppm of platinum, as was notice in studies of LG-4 glass. In contrast, the raw materials were found to be free from transition element impurities. Further studies to improve the quality of glass are essential to be undertaken.AcknowledgementWe acknowledge the contribution of Dr. R. Sen, Dr. Annapurna and other colleagues of the glass division, CGCRI Kolkata for readying of the phosphate laser glass samples for the XRF studies.ReferencesL. L. Seaver, LLNL report (925) 423 (Oct. 2010)J. H. Campbell and T. I. Suratwala, J. Non-Cryst. Solids 318, 2638 (2000).M. Mantler and M. Schreiner, X-Ray Spectrum. 29, 3 (2000)A.S. Joshi et al, EPJ wind vane of Conferences 59, 08001 (2013).M. K. Tiwari, P. Gupta, A. K. Sinha, S. R. Kane, A. K. Singh, S. R. Garg, C. K. Garg, G. S. Lodha and S. K. Deb, J. Synchrotron Rad. 20, 386 (2013).V.A. Sol, E. Papillon, M. Cotte, Ph. Walter, J. Susini, Spectrochimica Acta B 62, 63 (2007)