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Low temperature structural variations and molar heat capacity of stolzite, PbWO4 |
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| Authors: | Dmytro M Trots Anatoliy Senyshyn Björn C Schwarz |
| Institution: | a Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany b Hamburger Synchrotronstrahlungslabor am Deutsches Elektronen-Synchrotron, Notkestr. 85, D-22607 Hamburg, Germany c Fachbereich Materialwissenschaft, Technische Universität Darmstadt, Petersenstr. 23, D-64287 Darmstadt, Germany d Forschungsneutronenquelle Heinz-Maier-Leibnitz (FRM II), Technische Universität München, Lichtenbergstr. 1, D-85747 Garching b. München, Germany e Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden (IFW Dresden), Institut für Komplexe Materialien, Helmholzstrasse 20, PF 270116, D-01171 Dresden, Germany |
| Abstract: | The crystal structure, thermal expansion and heat capacity of PbWO4 (mineral name stolzite) scintillator material were comprehensively studied over a wide temperature range. No phase transitions were found down to 2 K (I41/a, scheelite structure type). A distinct feature of the temperature induced structural variations in PbWO4 are the different thermal elongations of shorter and longer Pb-O distances. The low-temperature thermal expansion of PbWO4 was parameterized on the basis of the 1st order Grüneisen approximation using a Debye function for the internal energy with a Debye temperature of 237 K, a bulk modulus of 67 GPa and a Grüneisen parameter of 1.08. The expansion along the c-axis is about 2.5-3 times higher in the range 23-290 K than along the a-direction. This pronounced anisotropy of the thermal expansion arises from the arrangements of rigid tetrahedral WO42− units along 〈100〉-directions while Pb2+ cations occupy the sites between WO42− in 〈001〉-directions. |
| Keywords: | Lead tungstate Scintillator material Crystal structure Thermal properties |
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