Multi-elemental segregation analysis of thallium bromide impurities purified by the repeated Bridgman technique

Santos, Robinson A. dos; Silva, Julio B. Rodrigues da; Gennari, Roseli Fernandes; Martins, Joao F. T.; Ferraz, Cauê de M.; Hamada, M.M.; Mesquita, C.H.

doi:10.1109/nssmic.2012.6551941

Cited by 3 publications

(5 citation statements)

References 12 publications

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“…X-ray diffraction patterns were obtained in a Siemens (D5005) diffractometer with CuK radiation (2 ranging from 20 ∘ to 60 ∘ ). The two sample slices from the middle crystal were prepared as a detector according to procedures described previously [7,17,18]. The crystal was sliced in wafers, cut transversally to direction (110), using a diamond saw, and lubricated with glycerine during the process.…”

Section: Methodsmentioning

confidence: 99%

Influence of Impurities on the Radiation Response of the TlBr Semiconductor Crystal

Santos¹,

Mesquita²,

Silva³

et al. 2017

Advances in Materials Science and Engineering

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Two commercially available TlBr salts were used as the raw material for crystal growths to be used as radiation detectors. Previously, TlBr salts were purified once, twice, and three times by the repeated Bridgman method. The purification efficiency was evaluated by inductively coupled plasma mass spectroscopy (ICP-MS), after each purification process. A compartmental model was proposed to fit the impurity concentration as a function of the repetition number of the Bridgman growths, as well as determine the segregation coefficients of impurities in the crystals. The crystalline structure, the stoichiometry, and the surface morphology of the crystals were evaluated, systematically, for the crystals grown with different purification numbers. To evaluate the crystal as a radiation semiconductor detector, measurements of its resistivity and gamma-ray spectroscopy were carried out, using 241Am and 133Ba sources. A significant improvement of the radiation response was observed in function of the crystal purity.

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Section: Methodsmentioning

confidence: 99%

Influence of Impurities on the Radiation Response of the TlBr Semiconductor Crystal

Santos¹,

Mesquita²,

Silva³

et al. 2017

Advances in Materials Science and Engineering

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“…Even though several studies on the preparation of room temperature semiconductor detectors and improvements in the methodology of purification, growth and characterization of the crystals have been carried out Oliveira et al, 2004;Oliveira et al, 2002;Matsumoto et al, 2002;Qiu, 2010, Gokhale et al 2014, Garg et al, 2014Gokhalea et al, 2015;Santos et al 2012), problems found in the room temperature semiconductor detectors are not yet completely resolved. Among them, the low collection efficiency of charge carriers and their stability, which are probably caused by impurities or defects created during the crystal growth.…”

Section: Introductionmentioning

confidence: 99%

Purification and Crystal Growth of the Bismuth (III) Iodide-influence of Trace Impurities on the Crystal Quality

Ferraz¹,

Armelin²,

Oliveira³

et al. 2017

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This work describes the experimental procedure of purification and preparation of BiI 3 crystals by Repeated Vertical Bridgman technique, aiming a future application of this semiconductor crystal as a room temperature radiation detector. The BiI 3 powder used as raw material was purified three times and, at each purification, the crystal was evaluated by systematic measurements of the reduction of the impurities, crystalline structure, stoichiometry and surface morphology. The reduction of the trace metal impurities in the BiI 3 , at each purification, was analyzed by Instrumental Neutron Activation Analysis (INAA), in order to evaluate the efficiency of the purification technique established in this work. It was demonstrated that the Repeated Bridgman technique is effective to reduce the concentration of many impurities in BiI 3 , such as Ag, As, Br, Cr, K, Mo, Na and Sb. The crystalline structure of the BiI 3 crystal purified twice and three times was similar to BiI 3 pattern. However, for BiI 3 powder and purified once, an intensity contribution of the BiOI was observed in the diffractograms. Improvement in the stoichiometric ratio was observed at each purification step, as well as the crystal surface morphology.

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“…O crescimento de cristais pode ser realizado por meio das técnicas de fusão, de epitaxia e de solução saturada. O presente trabalho foi focado prioritariamente na técnica de fusão, que foi empregada por meio do método de Bridgman (4,21,41,42,75) .…”

Section: Crescimento De Cristaisunclassified

“…A purificação do cristal de TlBr pode ser feita por repetições de processo de crescimento, método de Bridgman repetido (4,42,75) . A cada crescimento as impurezas tendem a migrar nas extremidades do cristal, dependendo do coeficiente de segregação k de cada impureza: (a) para k menor do que a unidade a região inicial do material solidificado será mais pura, porque o soluto será rejeitado pelo sólido e se acumulará no líquido, (b) para k maior do que a unidade, a região final do material solidificado será mais pura.…”

Section: Purificação E Crescimento De Cristais Pelo Método De Bridgmanunclassified

“…Gostilo e col. (33) realizaram um estudo comparativo entre o desempenho de cristais de TlBr crescidos pelo método de Bridgman e pelo método de refino zonal. Mais recentemente, têm-se observado, na literatura, um aumento significativo de estudos para obtenção de cristais de TlBr com melhor desempenho como detector de radiação, aprimorando diferentes parâmetros, tais como: eletrônica associada (34,35) , características físico-químicas do cristal (36,37,38) , elétricas (39) e impurezas (19,(40)(41)(42) . Adicionalmente, pesquisas sobre a degradação do sinal no decorrer do tempo (polarização), inerente a cristais semicondutores que operam à temperatura ambiente, também, tem aumentado (43)(44)(45)(46)(47) .…”

Section: Introductionunclassified

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Otimização da metodologia de preparação do cristal de brometo de Tálio para sua aplicação como detector de radiação

Santos¹

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In this work, TlBr crystals have been purified and grown by the Repeated Bridgman method from commercial TlBr materials and characterized to be used as radiation detectors.To evaluate the purification efficiency, studies on the impurity concentration decrease were performed after each growth, analyzing the trace impurities by inductively coupled plasma mass spectroscopy (ICP-MS). A significant decrease of the concentration of impurities in function of the purification number was observed. The grown crystals presented good crystalline quality according to the results of the x-ray diffraction analysis. To evaluate the crystals to be used as a semiconductor detector, measurements of the resistivity and the pulse height under 241 Am gamma rays were carried out. The radiation response was strongly dependent on the crystal purity. The Repeated Bridgman technique showed to be effective to reduce the concentration of impurities and to improve the TlBr crystal quality to be used as a radiation semiconductor detector. A compartmental model was proposed to fit the concentration/segregation of impurities in function of the Bridgman growth step number. This compartmental model is defined by differential equations and can be used to calculate the rate of migration of impurities. It proved to be a useful tool in predicting the number of Bridgman growth repetitions necessary to achieve the desired impurity concentration. The difference of the impurity migration rates between the crystals grown, using salts from different origins, was significant. Therefore, the choice of the starting salt should be performed experimentally, regardless of the statement nominal purity.

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Multi-elemental segregation analysis of thallium bromide impurities purified by the repeated Bridgman technique

Cited by 3 publications

References 12 publications

Influence of Impurities on the Radiation Response of the TlBr Semiconductor Crystal

Influence of Impurities on the Radiation Response of the TlBr Semiconductor Crystal

Purification and Crystal Growth of the Bismuth (III) Iodide-influence of Trace Impurities on the Crystal Quality

Otimização da metodologia de preparação do cristal de brometo de Tálio para sua aplicação como detector de radiação

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