inorganic chemical compound of bismuth, germanium and oxygen
BGO scintillator crystals covered with a ( partially dilapidated ) white rouge disguise Bismuth germanium oxide or bismuth germanate is an inorganic chemical compound of bismuth, germanium and oxygen. Most normally the term refers to the compound with chemical rule Bi 4 Ge 3 O 12 ( BGO ), with the cubic evlitine crystal social organization, used as a scintillator. ( The term may besides refer to a different compound with convention Bi12GeO20, an electro-optical material with sillenite structure, and Bi 2 Ge 3 O 9. )

Bi4Ge3O12.

Bi4Ge3O12 has a cubic crystal structure ( a = 1.0513 new mexico, z = 4, Pearson symbol cI76, space group I43d No. 220 ) and a concentration of 7.12 g/cm3. [ 1 ] When irradiated by X-rays or gamma rays it emits photons of wavelengths between 375 and 650 nm, with point at 480 nm it produces about 8500 photons per megaelectronvolt of the gamey energy radiation absorbed. It has beneficial radiation hardness ( parameters remaining stable up to 5.104 Gy ), senior high school scintillation efficiency, well energy resolution between 5 and 20 MeV, is mechanically strong, and is not hygroscopic. Its melting steer is 1050 °C. It is the most common oxide-based scintillator. [ 2 ]

Bismuth germanium oxide is used in detectors in particle physics, aerospace physics, nuclear music, geology exploration, and other industries. Bismuth germanate arrays are used for gamma pulse spectroscopy. BGO crystals are besides used in positron discharge imaging detectors. commercially available crystals are grown by the Czochralski serve and normally supplied in the form of cuboids or cylinders. large crystals can be obtained. crystal output is typically done around 1100 C, i.e. around 50 C above its military police [ 3 ] .

Bi12GeO20.

Bi12GeO20 has a cubic crystal structure ( a = 1.01454 nanometer, z = 2, Pearson symbol cI66, space group I23 No. 197 ) and a concentration of 9.22 g/cm3. [ 4 ] This bismuth germanate has high electro-optic coefficients ( 3.3 pm/V for Bi12GeO20 ), [ 5 ] making it utilitarian in nonlinear optics for build Pockels cells, and can besides be used for photorefractive devices for ultraviolet range.

The Bi12GeO20 crystals are piezoelectric, show hard electro-optical and acousto-optical effects, and discover limited use in the field of crystal oscillators and coat acoustic wave devices. [ 6 ] Single crystal rods and fibers can be grown by floating zone summons from a rod of assortment of bismuth oxide and germanium oxide. [ 7 ] The crystals are diaphanous and brown university colored. [ 8 ] The crystals of BGO and exchangeable compounds BSO ( Bi12SiO20, bismuth silicon oxide, sillenite ) and BTO ( Bi12TiO20 ), are photorefractive and photoconductive. BGO and BSO crystals are effective photoconductors with low dark conduction. They can be used in electro-optical applications, like ocular PROM, PRIZ spatial clean modulators, realtime hologram recording, correlators, and systems for adaptive correction of ultrashort laser pulses, and in fiber ocular sensors for electric and magnetic fields. Waveguide structures let uniform light over wide apparitional crop. Thin film sillenite structures, which can be deposited e.g. by sputtering, have wide range of potential applications. BSO crystals are used in optically address spatial light modulators and in fluent crystal light valves. [ 9 ] The ocular activeness of BTO is much smaller than of BGO and BSO. [ 10 ] Unlike slightly alike performing perovskites, sillenites are n’t ferroelectric. The materials can find function in phased-array optics.

When sputter, the target has to be kept below 450 °C as otherwise the bismuth vaporization pressure would get the composition out of stoichiometry, but above 400 °C to form the piezoelectric γ phase. [ 11 ]

See besides.

References.

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