Determination of the Temperature Coefficients of Selected Material Constants of Dilithium Tetraborate,
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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The first and second order temperature coefficients of the material constants ce11, c12, c44, ce66, and e15 of dilithium tetraborate Li2B4O7 have been measured over a temperature range of 20 deg C to 150 deg C. An improved resonator method was used to measure the fundamental zero mass loading antiresonant frequencies of selected pure-mode orientations of L12B4O7. Material constants extraction was performed using a linear least squares matrix method. The resulting material constant curves were fit with a third order power series to obtain their corresponding temperature coefficients. The calculated temperature coefficients of the material constants c12, c44, c66, and e15 of Li2B4O7 were used to predict the zero mass loading antiresonant c12, c44, c66, and of frequencies of the crystal samples with average errors of 1.20 for thickness excitation and 0.285 for lateral excitation.
- Physical Chemistry