Broadband NIR luminescence from a new bismuth doped Ba_2B_5O_9Cl crystal: evidence for the Bi^0 model

Abstract

A new type of bismuth doped Ba(2)B(5)O(9)Cl crystal is reported to exhibit broadband near infrared (NIR) photoluminescence at room temperature, which has been identified here originating from elementary bismuth atom. Rietveld refining, static and dynamic spectroscopic properties reveal two types of Bi(0) centers in the doped compound due to the successful substitution for two different nine-coordinated barium lattice sites. These centers can be created only in a reducing condition, and when treated in air and N(2)/H(2) flow in turn, they can be removed and restored reversely. As the dwelling time is prolonged in N(2)/H(2) at high temperature, conversion from Bi(2+) to Bi(0), as reflected by changes of their relative emission intensities, is witnessed in the crystal of Ba(2)B(5)O(9)Cl:Bi. The lifetime of the NIR luminescence was observed in a magnitude of ~30 μs, rather different from bismuth doped either glasses or crystals reported previously.

Broadband infrared luminescence in γ-ray irradiated bismuth borosilicate glasses

“…The origin of the darkening is due to formation of new bismuth color centers, which may involve the following steps: (a) the production, through absorption of the γ-photon energy and subsequent ionization, of free electrons with a range of energies; and (b) the capture of the free electrons by bismuth ions. Zheng et al found a 534 nm absorption band initiated from bismuth atom in bismuth-doped Ba 2 B 5 O 9 Cl crystal [6]. The similarity in band position would suggest the same origin for the present γ-ray irradiated samples.…”

“…The IR luminescence depends on the γ-ray irradiation dose and the concentration of Bi 2 O 3 . The thermal stability of the γ-ray irradiated IR luminescence center is studied, and the origin of the IR luminescence center has been suggested.Since the 1990s bismuth-activated inorganic materials, e.g., glasses [1-3] and crystals [4][5][6], have been extensively studied for their broadband infrared (IR) (in a range of from 1000 up to 4000 nm) luminescence properties and practical applications in solid-state lasers [7] and fiber amplifiers [8]. Despite the great success in preparing new laser devices and materials, the nature of the optically active IR luminescence center remains disputable (see a recent review article [9]).…”

“…Since the 1990s bismuth-activated inorganic materials, e.g., glasses [1][2][3] and crystals [4][5][6], have been extensively studied for their broadband infrared (IR) (in a range of from 1000 up to 4000 nm) luminescence properties and practical applications in solid-state lasers [7] and fiber amplifiers [8]. Despite the great success in preparing new laser devices and materials, the nature of the optically active IR luminescence center remains disputable (see a recent review article [9]).…”

“…Despite the great success in preparing new laser devices and materials, the nature of the optically active IR luminescence center remains disputable (see a recent review article [9]). Experimental evidence presently exists for two sides that bismuth in high (e.g., Bi 5 [1]) or low-valent-states (e.g., Bi [10], Bi 0 [6], Bi − 2 or Bi 2− 2 [11]) is responsible for the IR luminescence. So far, most researchers have only agreed on that low-valent-state bismuth is most likely at the origin of the IR luminescence [9].…”

Near infrared photoluminescence of the univalent bismuth impurity center in leucite and pollucite crystal hosts

“…The Bi 3+ ion in the common oxidation state +3 has no optical transitions in NIR and the observed emission was attributed to possible Bi 5+ , 1 Bi 2+ , 20 Bi + , 21 Bi 0 , 8,9,22 Bi 2 À , Bi 2 2À , 23 and bismuth cluster species. 24 The related information was also summarized in the recent review.…”