Effect of Melt Composition on the Luminescent Properties of Czochralski-Grown Li2B4O7 Single Crystals

Abstract

Li 2 B 4 O 7 (LTB) single crystals are grown from stoichiometric and B 2 O 3 -enriched (1.6 and 2.4 mol %) melts. At large B 2 O 3 excesses, the thermoluminescence intensity in the crystals is markedly higher, attesting to an increased density of structural defects. LTB crystals grown from B 2 O 3 -enriched melts may contain zones enriched in two types of defects. Defects of one type result from the breaking of bonds involving bridging oxygens, without significant changes in the position of neighboring atoms. Defects of the other type appear at large B 2 O 3 excesses in the melt, which enable more significant changes in the structure of the boronoxygen framework, leading to the formation of nanoscale regions differing in composition from LTB. The present results may be helpful in assessing the quality of LTB single crystals and in optimizing the crystal growth of LTB.

An Overview on Preparation and TL Characterization of Lithium Borates for Dosimetric Use

“…These properties of a shoulder peak imply that it has a complicated nature. Such maxima are claimed to root from superposition of a number of local trapping levels [6]. In a similar way, peaks observed around 300 o C are not assigned to good TL properties.…”

“…Lithium tetraborate is also known to have a high radiation resistivity and a wide operation dose range. Furthermore it is an important feature of lithium tetraborate that it is only weakly dependent on the dose on ionizing radiation energy [6].…”

“…Such devices convert acoustic wave to electrical signal and vice versa making use of the piezoelectric effect of certain materials. The major materials used in this area are quartz, lithium niobate, lithium tantalate, lanthanum gallium silicate and lithium tetraborate is proved to be a pretty logical alternative [6,19,20,24,25]. Moreover, lithium borates are known to be used in sensors like pressure sensors and pyroelectric sensors [24].…”

Influence of reducing annealing on the luminescent properties of Li2B4O7:Cu single crystals

“…3). Distinct maximums at 304 and 360 nm are observed in the XL spectra for non-doped LTB single crystals [9,13]. Hence, their presence should be related to the proper defects of the crystalline lattice.…”

“…It has been found that copper addition is involved in the LTB structure at the lithium ion site [5,6]. One has to take into account that the proper genetic defects also occur in the LTB single crystals, in particular, lithium and oxygen vacancies as well as clusters related to the violation of the relation between the boron-oxygen triangles and tetrahedrons [5,9].…”