Effect of non-stoichiometry on some properties of lead tungstate single crystals

• Published in: Journal of crystal growth Vol. 169; no. 2; pp. 304 - 308
• Main Authors: Sabharwal, S.C., Sangeeta, Desai, D.G., Karandikar, S.C., Chauhan, A.K., Sangiri, A.K., Keshwani, K.S., Ahuja, M.N.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.1996; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity); Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Other luminescence and radiative recombination; Physics; Thermoluminescence; Monocrystals; Inorganic compounds; Lead tungstates; Gamma radiation; Ternary compounds; Physical radiation effects; Transition element compounds; Experimental study; Optical absorption; Nonstoichiometry; Thermoluminescence
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/S0022-0248(96)00387-9

The effect of stoichiometric deviations on the optical absorption, gamma rays induced absorption and thermoluminescence (TL) from PbWO 4 (PWO) single crystals has been investigated. The stoichiometric deviations are found to develop yellowish coloration in this crystal. This problem has been overcome by purifying the starting powder for minute stoichiometric deviations through repeated crystallisations. In the case of non-stoichiometric crystals a broad absorption over the wavelength range 400–500 nm is observed. This absorption gets further enhanced when the crystal is subjected to γ-ray irradiation. Whereas, the stoichiometric crystals, which are colourless, are found not to develop coloration for gamma exposures as high as 10 Mrad. The presence of weak TL in both types of crystals is observed for the radiation exposures of 10 Mrad. For colourless crystals, only one TL glow peak at 170°C is recorded over the temperature range 30–400°C. A shift in the glow peak temperature towards the lower temperature side is observed in the case of non-stoichiometric crystals. This result can be used to detect minute stoichiometric deviations in PWO.