Effect of ion implantation on the strength of sapphire at 300-600 degrees C

Ion implantation with B-11(+) or Si-28(+) at 1000 degreesC doubled the ring -on-ring flexure strength of c-plane sapphire disks tested at 300 degreesC but had little effect on strength at 500 or 600 degreesC. Disks were implan ted on the tensile surface with 2 x 10(17) B/cm(2) (half at 40 keV and half at 160 keV) or 1 x 10(17) Si/cm(2) (80 keV). Sapphire implanted with 1 x 1 0(18) B/cm(2) had only half as much flexure strength at 300 degrees or 500 degreesC as sapphire implanted with 2 x 10(17) B/cm(2). Implantation with B , Si, N, Fe or Cr had no effect on the c-axis compressive strength of sapph ire at 600 degreesC. Boron ion implantation (2 x 10(1)7 B/cm(2), half at 40 keV and half at 160 keV) induced a compressive surface force per unit leng th of 1.9 x 10(2) N/m at 20 degrees and 1.4 x 10(2) N/m at 600 degreesC. Th e infrared emittance at 550-800 degrees of B-implanted sapphire at a wavele ngth of 5 mum increased by 10-15% over that of unimplanted sapphire. Infrar ed transmittance of sapphire implanted with B, Si or N at either 1000 degre esC or 25 degreesC is within similar to1-3% of that of unimplanted material at 3.3 mum. Implantation with Fe or Cr at 25 degreesC decreases the transm ittance by 4-8% at 3.3 mum, but implantation at 1000 degreesC decreased tra nsmittance by only 2-4% compared to unimplanted material. (C) 2001 Kluwer A cademic Publishers.