Anisotropic thermal expansion in wurtzite-type crystals

• Published in: Journal of materials science Vol. 35; no. 10; pp. 2451 - 2454
• Main Authors: IWANAGA, H, KUNISHIGE, A, TAKEUCHI, S
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 2000; Springer Nature B.V
• Subjects: Anharmonicity; Anisotropy; Cadmium sulfide; Condensed matter: structure, mechanical and thermal properties; Crystal lattices; Elasticity; Exact sciences and technology; Gruneisen parameter; Heat capacities of solids; Lattice parameters; Materials science; Physics; Temperature; Temperature dependence; Thermal expansion; Thermal expansion; thermomechanical effects and density; Thermal properties of condensed matter; Thermal properties of crystalline solids; Wurtzite; Zinc oxide; Temperature dependence; Inorganic compounds; Gallium nitrides; Transition element compounds; Cadmium sulfides; Grueneisen constant; XRD; Experimental study; Lattice parameters; Cadmium selenides; Thermal expansion; Zinc oxides; Anisotropy; Beryllium oxides; Aluminium nitrides; Wurtzite structure
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1023/a:1004709500331

The temperature dependence of the lattice parameters of six wurtzite-type crystals, BeO, AlN, GaN, ZnO, CdSe, and CdS, has been measured by X-ray powder diffractometry. The thermal expansion changes nonlinearly with temperature and is anisotropic; the expansion along the a-axis is larger than that along the c-axis (more than 50% larger in ZnO, CdS and CdSe), resulting in a decrease of the c/a ratio with increasing temperature. The calculated Grüneisen parameters range between 0.27 and 1.45 and have a positive correlation with the bulk moduli. The anisotropic thermal expansion is associated with the anisotropies of both elasticity and anharmonicity.