Accuracy analysis and deduced strategy of measurements applied to Ca3TaGa3Si2O14 (CTGS) material characterization

Based on the least squares method which is arranged to the problem of fitting theoretical to experimental measured variables, such as phase velocities of acoustic waves and/or resonant frequencies, the environment of the minimum sum of squares (SSQ) has been analyzed, similarly to [1]. This is done by forming a “sensitivity matrix” (or Jacobian matrix: derivatives of measured variables with respect to each searched material parameter) based on a parameter set found in first approximation. As a result of evaluating the SSQ environment the full set of material parameter accuracies is available. In such a way the overall evidence of used experimental method is seen and can be improved if applicable, i.e. an optimum measurement strategy can be developed. The method is used in our case preferentially to angular dependent measurements of surface acoustic wave (SAW) velocities on wafers of single crystal Ca
₃
TaGa
₃
Si
₂
O
₁₄
(CTGS), a promising member of langasite family.