50 MeV Li 3+ irradiation effects on the thermal expansion of Ca 1− xSr xZr 4P 6O 24

Abstract

The influence of 50 MeV Li 3+ ion irradiation on the thermal expansion of the low thermal expansion ceramic Ca 1− x Sr x Zr 4P 6O 24 ( x=0.00, 0.25, 0.50, 0.75 and 1.00) belonging to the sodium zirconium phosphate (NZP) family of ceramics was studied in the temperature range 300–1100 K. The observed changes in XRD, microstructure and thermal expansion are reported. These changes are strongly dependent upon the strontium substitution at calcium sites in the basic structure. The XRD and scanning electron microscope (SEM) studies indicate that the ion irradiation causes amorphization, especially at the grain boundaries. The thermal expansion hysteresis reduces due to Sr substitution and is further reduced upon irradiation. It is suggested that the amorphization due to irradiation helped release of thermal stress and thereby lead to the reduction in the hysteresis in thermal expansion. The composition with x=0.50 having low coefficient of thermal expansion (CTE), low hysteresis and the least thermal expansion anisotropy is least affected by the Li 3+ irradiation and hence may qualify as the radiation resistant material.