We report measurements of all the material constants necessary to fully characterize barium borate as a nonlinear optical material. All data was taken on crystals supplied by Professor Chuangtien Chen, Fuzhou, People’s Republic of China. We have determined the crystal structure, the optical absorption, the refractive indices from the UV to the near IR, the thermo-optic coefficients, the nonlinear optical or coefficients, the resistance to laser damage, the elastic constants, the thermal expansion, thermal conductivity and dielectric constants, and the fracture toughness. This data is used to evaluate barium borate for a variety of applications. We find that, in general, barium borate has a low acceptance angle, and that despite its higher optical nonlinearity, it is therefore not significantly more efficient than other commonly available materials, except in the UV below 250 nm. On the other hand, it has a high damage threshold, it is physically robust, it has good UV and IR transparency, and it has excellent average power capability. It permits deep UV generation, and has great potential for generating tunable visible and IR light as an optical parametric amplifier.

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Abstract. The nine adiabatic elastic stiffness constants of synthetic single-crystal fayalite, FezSiO4, were measured as functions of pressure (range, 0 to 1.0 GPa) and temperature (range, 0 to 40 ~ C) using the pulse superposition ultrasonic method. Summary calculated results for a dense fayalite polycrystalline aggregate, based on the HS average of our single-crystal data, are as follows: Vp-6.67km/s; V~ = 3.39 km/s; K = 127.9 GPa; # = 50.3 GPa; (~K/SP)r = 5.2; (8 #/SP)r = 1.5;(~ K/~ T)e = --0.030 GPa/K; and, (~#/8 T)p = -0.013 GPa/K (the pressure and temperature data are referred to 25~ and 1 atm, respectively). Accuracy of the single-crystal results was maintained by numerous cross and redundancy checks.Compared to the single-crystal elastic properties of forsterite, MgzSiO4, the fayalite stiffness constants, as well as their pressure derivatives, are lower for each of the on-diagonal (Cij for which i=j) values, and generally higher for the off-diagonal (Cij for which i*j) data. As a result, the bulk moduli (K) and dK/dP for forsterite and fayalite are very similar, but the rigidity modulus (#) and d#/dP for polycrystalline fayalite are much lower than their forsterite counterparts. The bulk compression properties derived from this study are very consistent with the static-compression x-ray results of Yagi et al. (1975). The temperature dependence of the bulk modulus of fayalite is somewhat greater (in a negative sense) than that of forsterite. The rigidity dependencies are almost equivalent. Over the temperature range relevant to this study, the elastic property results are generally consistent with the data of Sumino (1978), which were obtained using the RPR technique. However, some of the compressional modes are clearly discrepant. The elastic constants of fayalite appear to be less consistent with a theoretical HCP model (Leibfried 1955) than forsterite, reflecting the more covalent character of the Fe-O bonding in the former.

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The compressional and shear wave velocities in a series of polycrystal samples of magnesiowustite (Mgx, Fe1‐x)YO have been measured using the pulse superposition method. Each specimen was characterized in terms of composition, stoichiometry, and porosity by chemical and microprobe analysis, and by X ray diffraction. In addition, the measurement of velocity in three perpendicular directions has demonstrated that the individual specimens were isotropic to within 1/4%. The application of empirical corrections to account for the effects of nonstoichiometry and porosity has allowed the determination of the isotropic elastic properties for the entire stoichiometric (Mg,Fe)O solid solution series. Our results for MgO (KS = 1619 ± 16 kbar, μ = 1304 ± 16 kbar) are consistent with previous determinations of these properties from single‐crystal measurements. In the case of FeO (KS = 1835 ± 31 kbar, μ = 589 ± 14 kbar), our data generally correspond to the results of previous investigations, which used both ultrasonic and static compression techniques, when corrections are applied for the effects of nonstoichiometry. Our measurements on Fe‐rich magnesiowustites have demonstrated clearly that the isotropic elastic properties, especially the bulk modulus KS, are strongly dependent on the defect structure (nonstoichiometry) of the specimens. The increasing number of vacancy clusters toward the FeYO end‐member correlates with decreasing bulk modulus and anomalously high values of (∂K /∂P)T. However, when corrections are applied for the nonstoichiometric effects, the elastic properties of the (Mg, Fe)O solid solution series behave according to the linear compliance relation proposed by Liu (1968) and Jackson et al. (1978).