The Influence of Cation Impurities on the Scintillation Performance of <formula formulatype="inline"><tex Notation="TeX">${{\hbox {SrI}}_2}$</tex></formula>(Eu)

Abstract

To better identify the influence of cation impurities on the scintillation performance of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {SrI}}_2}$</tex> </formula> (Eu), <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {SrI}}_2}$</tex> </formula> crystals were grown, each co-doped with 4 mol% <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Eu}}^{2 +}}$</tex></formula> and 0.2 mol% of one of the following: <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Mg}}^{2 +}}$</tex> </formula> , <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Ba}}^{2 +}}$</tex> </formula> , <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Cs}}^ +}$</tex> </formula> , <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Ca}}^{2 +}}$</tex> </formula> , <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Fe}}^{2 +}}$</tex> </formula> , <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Cu}}^ +}$</tex> </formula> , <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Na}}^ +}$</tex> </formula> , and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Sn}}^{2 +}}$</tex> </formula> . Four 10 mm diameter crystals were grown at a time by the vertical Bridgman-Stockbarger method. The segregation behavior and the scintillation performance of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$10~\hbox{mm dia.}\times 6~\hbox{mm}$</tex></formula> cylinders and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$7~\hbox{mm}\times 6~\hbox{mm}\times 2~\hbox{mm}$</tex></formula> cuboids were characterized. <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Mg}}^{2 +}}$</tex> </formula> , <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Cs}}^ +}$</tex> </formula> , <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Fe}}^{2 +}}$</tex> </formula> , and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Cu}}^ +}$</tex> </formula> impurities did not adversely affect scintillation properties, and segregated during growth. However, <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Na}}^ +}$</tex></formula> , <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Ba}}^{2 +}}$</tex> </formula> , and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Ca}}^{2 +}}$</tex> </formula> did not segregate well and degraded light yield and energy resolution, especially at the larger sample size. <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {Sn}}^{2 +}}$</tex></formula> proved to be the most detrimental to light yield and produced a secondary emission peak at 600 nm, but did not affect the non-proportionality response. The results of this study suggest that <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${{\hbox {SrI}}_2}$</tex> </formula> (Eu) can tolerate a surprisingly large amount of cation impurities. These findings suggest that the purity requirements for starting materials can be relaxed, and purification efforts may be adjusted to target only the most harmful impurities.