Elastic moduli of pressure-sintered nickel oxide

The elastic moduli of pressure-sintered nickel oxide near theoretical density have been measured by three different techniques. The values of Young's modulus and the shear modulus at room temperature determined by the resonant sphere method were 9.58×1011 dynes/cm2 and 3.38×1011 dynes/cm2, respectively. The value of Young's modulus determined by a three-part composite oscillator technique was 9.56×1011 dynes/cm2, in good agreement with the resonant sphere measurements. Measurements of Young's modulus and shear modulus by the pulse-transmission method were subject to fairly large end effects, which gave lower values. The temperature of the anomalous increase in Young's modulus and in relative acoustic loss was found to be 250°C±1/2°C, in excellent agreement with previously reported measurements for the Néel temperature of nickel oxide.